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salm1  (ProSci Incorporated)


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    Structured Review

    ProSci Incorporated salm1
    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using <t>SALM1</t> or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.
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    Images

    1) Product Images from "SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering"

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    Journal: The EMBO Journal

    doi: 10.15252/embj.2018101289

    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.
    Figure Legend Snippet: Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Techniques Used: Control, Protein-Protein interactions, Immunoprecipitation, Plasmid Preparation, Co-Immunoprecipitation Assay

    Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.
    Figure Legend Snippet: Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Techniques Used: Cell Culture, Staining, Marker, MANN-WHITNEY

    A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.
    Figure Legend Snippet: A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Techniques Used: Transfection, Expressing, Cell Culture, Staining

    A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.
    Figure Legend Snippet: A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Techniques Used: Expressing, Marker, Transfection, Cell Culture, Infection, Knockdown, shRNA

    Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.
    Figure Legend Snippet: Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Techniques Used: Expressing, Transfection

    A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.
    Figure Legend Snippet: A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Techniques Used: Transfection, Expressing, Staining, Fluorescence, Sequencing, Mutagenesis, Construct, Diffusion-based Assay

    A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.
    Figure Legend Snippet: A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Techniques Used: Cell Culture, Infection, Staining, shRNA, Expressing, Control, Marker, Transfection

    A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.
    Figure Legend Snippet: A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Techniques Used: Cell Culture, Infection, Construct, Staining

    A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.
    Figure Legend Snippet: A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Techniques Used: Isolation, Staining, Infection, shRNA, Construct, Membrane

    Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.
    Figure Legend Snippet: Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Techniques Used: Patch Clamp, Isolation, Infection, Construct, Control, shRNA, Expressing, Knockdown, Mutagenesis, Fluorescence, Transfection, MANN-WHITNEY

    Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.
    Figure Legend Snippet: Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Techniques Used:



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    Image Search Results


    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Control, Protein-Protein interactions, Immunoprecipitation, Plasmid Preparation, Co-Immunoprecipitation Assay

    Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Cell Culture, Staining, Marker, MANN-WHITNEY

    A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Transfection, Expressing, Cell Culture, Staining

    A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Expressing, Marker, Transfection, Cell Culture, Infection, Knockdown, shRNA

    Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Expressing, Transfection

    A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Transfection, Expressing, Staining, Fluorescence, Sequencing, Mutagenesis, Construct, Diffusion-based Assay

    A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Cell Culture, Infection, Staining, shRNA, Expressing, Control, Marker, Transfection

    A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Cell Culture, Infection, Construct, Staining

    A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Isolation, Staining, Infection, shRNA, Construct, Membrane

    Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques: Patch Clamp, Isolation, Infection, Construct, Control, shRNA, Expressing, Knockdown, Mutagenesis, Fluorescence, Transfection, MANN-WHITNEY

    Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Article Snippet: The following primary antibodies were used for intracellular and/or surface staining: rabbit polyclonal SALM1 1:100 (Synaptic Systems), chicken polyclonal MAP2 1:10,000 (Abcam Cat# ab75713, RRID:AB_1310432), guinea pig polyclonal VGluT1 1:5,000 (Millipore Cat# AB5905, RRID:AB_2301751), guinea pig polyclonal Homer 1:300 (Synaptic Systems Cat# 160 004, RRID:AB_10549720), mouse monoclonal Smi312 1:1,000 (BioLegend Cat# 837904, RRID:AB_2566782), guinea pig polyclonal Synaptophysin1 1:250 (Synaptic Systems Cat# 101 004, RRID:AB_1210382), rabbit polyclonal GFP 1:500 (GeneTex Cat# GTX20290, RRID:AB_371415), guinea pig polyclonal GFP (Synaptic Systems Cat# 132 005, RRID:AB_11042617), mouse monoclonal GFP (Thermo Fisher Scientific Cat# 14‐6674‐82, RRID:AB_2572900), mouse monoclonal mCherry 1:1,000 (Signalway Cat# T515, RRID:AB_2721246), rabbit polyclonal mCherry (GeneTex Cat# GTX128508, RRID:AB_2721247), mouse monoclonal Flag 1:1,000 (Sigma‐Aldrich Cat# F1804, RRID:AB_262044), and/or mouse monoclonal HA 1:500 (Roche Cat# 11666606001, RRID:AB_514506).

    Techniques:

    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Control, Protein-Protein interactions, Immunoprecipitation, Plasmid Preparation, Co-Immunoprecipitation Assay

    Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Cell Culture, Staining, Marker, MANN-WHITNEY

    A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Transfection, Expressing, Cell Culture, Staining

    A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Expressing, Marker, Transfection, Cell Culture, Infection, Knockdown, shRNA

    Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Expressing, Transfection

    A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Transfection, Expressing, Staining, Fluorescence, Sequencing, Mutagenesis, Construct, Diffusion-based Assay

    A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Cell Culture, Infection, Staining, shRNA, Expressing, Control, Marker, Transfection

    A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Cell Culture, Infection, Construct, Staining

    A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Isolation, Staining, Infection, shRNA, Construct, Membrane

    Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Patch Clamp, Isolation, Infection, Construct, Control, shRNA, Expressing, Knockdown, Mutagenesis, Fluorescence, Transfection, MANN-WHITNEY

    Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques:

    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Immunoprecipitation, Plasmid Preparation, Co-Immunoprecipitation Assay

    Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Cell Culture, Staining, Marker, MANN-WHITNEY

    A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Transfection, Expressing, Cell Culture, Staining

    A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Expressing, Marker, Transfection, Cell Culture, Infection, shRNA

    Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Expressing, Transfection

    A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Transfection, Expressing, Staining, Fluorescence, Sequencing, Mutagenesis, Construct, Diffusion-based Assay

    A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Cell Culture, Infection, Staining, shRNA, Expressing, Marker, Transfection

    A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Cell Culture, Infection, Construct, Staining

    A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Isolation, Staining, Infection, shRNA, Construct

    Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques: Patch Clamp, Isolation, Infection, Construct, shRNA, Expressing, Mutagenesis, Fluorescence, Transfection, MANN-WHITNEY

    Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Article Snippet: We used a rabbit polyclonal SALM1 antibody targeted against the 638–788 cytoplasmic amino acid fragment of mouse SALM1 developed by Synaptic Systems in all experiments labeling SALM1 except immunoelectron microscopy.

    Techniques:

    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Control, Protein-Protein interactions, Immunoprecipitation, Plasmid Preparation, Co-Immunoprecipitation Assay

    Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Cell Culture, Staining, Marker, MANN-WHITNEY

    A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Transfection, Expressing, Cell Culture, Staining

    A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Expressing, Marker, Transfection, Cell Culture, Infection, Knockdown, shRNA

    Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Expressing, Transfection

    A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Transfection, Expressing, Staining, Fluorescence, Sequencing, Mutagenesis, Construct, Diffusion-based Assay

    A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Cell Culture, Infection, Staining, shRNA, Expressing, Control, Marker, Transfection

    A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Cell Culture, Infection, Construct, Staining

    A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Isolation, Staining, Infection, shRNA, Construct, Membrane

    Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques: Patch Clamp, Isolation, Infection, Construct, Control, shRNA, Expressing, Knockdown, Mutagenesis, Fluorescence, Transfection, MANN-WHITNEY

    Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Article Snippet: For immunoEM, we used a different antibody (ProSci Cat#5067, RRID:AB_10906317) that recognized SALM1 with high specificity ( ).

    Techniques:

    Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Heat map showing 22 putative interactors of the Munc18‐1/CASK/Mint1/Lin7b presynaptic complex identified in a proteomics screen using CASK, Mint1, or Lin7b as bait. Detection of the putative interactors using SALM1 or GluR2 (control) as bait is also shown. Bar values indicate average log10 LFQ intensity of three replicates. Gray indicates no detection in the IP. Partial interactome of the putative SALM1/Munc18‐1/CASK/Mint1/Lin7b complex identified by IP‐MS analysis in (A). Blue lines indicate interactions identified in the IP‐MS screen using CASK, Mint1, or Lin7b as bait. Red lines indicate interactions identified by reverse IP‐MS with SALM1. Black lines indicate previously established interactions with the Munc18‐1/CASK/Mint1/Lin7b complex (Butz et al , ; Tabuchi et al , ). Co‐immunoprecipitation of V5‐tagged cytoplasmic SALM1, SALM1ΔPDZ, or an empty vector with CASK in HEK cells. The co‐IP was repeated 3 times.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Control, Protein-Protein interactions, Immunoprecipitation, Plasmid Preparation, Co-Immunoprecipitation Assay

    Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Sandwich‐cultured mouse hippocampal neurons stained at DIV16 for endogenous SALM1 (green), dendritic marker MAP2 (blue), and synapse markers Homer or VGluT1 (red), or the axonal marker SMI‐312 (red). Boxes indicate area of zoom. Arrows indicate overlap between SALM1 and synapse markers. Bars = 10 μm in full neuron images. Bars = 5 μm in zoomed images. Average overlap ± SEM of SALM1 clusters with VGluT1 or Homer puncta. Numbers in bars indicate number of zoomed images/total number of neurons in two independent experiments. Example images showing differential overlap of SALM1 with Homer or VGluT1. Bars = 0.5 μm. Electron micrographs showing subsynaptic localization of endogenous SALM1 in mouse hippocampal brain slices. SALM1 immunogold particles are detected in presynapses (orange and magenta arrows) and postsynapses (cyan and blue arrows). Bars = 100 nm. Mean percentage of gold particles ± SEM detected in pre‐ versus postsynapses of mouse hippocampal slices stained for SALM1. Percentages are based on detected gold particles in 32 synapses in hippocampal brain slices of three different animals (Mann–Whitney U ‐tests with Bonferroni correction, ns = not significant, * P < 0.025 after Bonferroni correction). Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Cell Culture, Staining, Marker, MANN-WHITNEY

    A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Collapsed z ‐stack image of a calcium phosphate transfected HEK cell showing surface expression (red) and intracellular expression (green) of SALM1‐pHl. B Single z ‐slice from the z ‐stack image given in (A). C, D Example images of calcium phosphate transfected HEK cells expressing GFP, SALM1‐pHl, Nrxn1β‐pHl, or HA‐Nlg1 (green) co‐cultured with DIV9‐10 sandwich‐cultured mouse hippocampal neurons. Dendrites were stained for MAP2 (blue), postsynapses for Homer (C), and presynapses for VGluT1 (D) (red). E, F Average number of postsynapses ± SEM (E) or presynapses ± SEM (F) per HEK cell. Numbers in bars indicate total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc pairwise comparisons were used for (E) ( P < 0.001) and (F) ( P < 0.001). ns = not significant and *** P < 0.001. Data information: Scale bars (A–D) = 5 μm. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Transfection, Expressing, Cell Culture, Staining

    A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–J (A and F) Schematic representation of SALM1‐depleted neurons forming postsynapses on Neurexin expressing HEK cells (A) or forming presynapses on Neuroligin expressing HEK cells (F). Example images showing postsynapses positive for postsynaptic marker Homer (red) formed on calcium phosphate transfected HEK cells expressing Nrxn1β‐pHl (B) or showing presynapses positive for presynaptic vesicle marker VGluT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 (G). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with scrambled or SALM1 knockdown (shRNA#2) lentivirus (DIV3→10). Bars = 5 μm. Average number of Homer (C) or VGluT1 (H) particles ± SEM detected per HEK cell. Average size of the Homer (D) or VGluT1 (I) particles ± SEM detected per HEK cell. Average intensity ± SEM of Homer (E) and VGluT1 (J) puncta detected per HEK cell. For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for (C and H) ( P = 0.001), (D) ( P = 0.065), (E) ( P = 0.327), (I) ( P = 0.06), and (J) ( P = 0.003). ns = not significant, * P < 0.05 and ** P < 0.01. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Expressing, Marker, Transfection, Cell Culture, Infection, Knockdown, shRNA

    Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Examples of expression patterns of Nrxn1β‐FLAG or HA‐Nlg1 at the surface of calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and Nrxn1β‐FLAG (green) when co‐expressed in calcium phosphate transfected HEK cells. Example of surface expression patterns of SALM1‐pHl (red) and HA‐Nlg1 (green) when co‐expressed in calcium phosphate transfected HEK cells. Data information: Images represent collapsed z ‐stacks. Blue boxes indicate area of zoom; white arrows indicate examples of SALM1 puncta in close proximity of Nlg1 or Nrxn1β puncta. Bars = 5 μm in full HEK cell images. Bars = 2 μm in zoomed images.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Expressing, Transfection

    A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A–I (A, C) Single z ‐slice images through calcium phosphate transfected HEK cells co‐expressing SALM1‐pHl and Nrxn1β‐FLAG treated with DMSO (A) or Latrunculin A (C) and stained for surface GFP (blue), surface FLAG (green), and Phalloidin (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (B, D) Representative fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (A, C). SALM1 puncta are highlighted in yellow. (E) Partial amino acid sequence of the transmembrane and intracellular juxtamembrane domain of SALM1 and mutant SALM1 RAKA . The point mutations R556A and K558A are indicated by * and highlighted in red. Single z‐slice images through HEK cells co‐expressing calcium phosphate transfected SALM1‐pHl (F) or SALM1 RAKA (H) (blue, surface staining) with Nrxn1β‐FLAG (green, surface staining) and lentivirally expressed PLC‐PH‐mCherry (red). White boxes indicate area of zoom; zoomed images are depicted below the full image for each channel. White lines in merged zoomed images represent cross sections used for intensity plots in (B, D). Bars = 5 μm in full HEK cell images. Bars = 3 μm in zoomed images. (G, I) Fluorescence intensity plots of cross sections depicted by white lines in the zoomed merge image in (F, H). SALM1 puncta are highlighted in yellow. J Average number of surface Nrxn1β‐FLAG clusters ± SEM per HEK cell for HEK cells expressing the different indicated constructs. K Average Nrxn1β‐FLAG diffusion ratio (D‐ratio) ± SEM per HEK cell for HEK cells expressing the different indicated constructs. Data information: The n is indicated in the bars and represents the total number of cells/total number of independent cultures. S1 = SALM1‐pHl, Nrxn = Nrxn1β‐FLAG, and S1 RAKA = SALM1 RAKA ‐pHl. Kruskal–Wallis tests with post hoc paired comparisons were used on (J) ( P < 0.001) and (K) ( P < 0.001). *** P < 0.001. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Transfection, Expressing, Staining, Fluorescence, Sequencing, Mutagenesis, Construct, Diffusion-based Assay

    A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 10 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG (green, surface staining) and scrambled, shRNA#2, shRNA#2+rSALM1, or shRNA#2+rSALM1 RAKA . Arrows indicate overlap between VGluT1 puncta and Nrxn1β‐FLAG clusters. Bars = 5μm B Average surface Nrxn1β‐FLAG intensity ± SEM detected in VGluT1 puncta per neuron. C Schematic representation of neurons expressing GFP (control), Nrxn1βFLAG (green puncta), or SALM1‐pHl with Nrxn1βFLAG forming presynapses (red puncta) on HA‐Nlg1 expressing HEK cells. D Example images showing presynapses positive for presynaptic marker VGLuT1 (red) formed on calcium phosphate transfected HEK cells expressing HA‐Nlg1 and stained for HEK cell filler GFP and surface Nrxn1β‐FLAG (green). HEK cells were co‐cultured for 24 h with sandwich‐cultured mouse hippocampal neurons infected with GFP (control), Nrxn1β‐FLAG, SALM1‐pHl, SALM1‐pHl+Nrxn1β‐FLAG, SALM1 RAKA ‐pHl+Nrxn1β‐FLAG, or SALM1ΔPDZ‐pHl+Nrxn1β‐FLAG lentivirus (DIV3→10). Bars = 5 μm in full HEK cell images. Bars = 1 μm in zoomed images. E–G Average number of VGluT1 puncta (E), puncta size (F), and puncta intensity (G) ± SEM detected per HEK cell. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used on data sets (B) ( P < 0.001), (E) ( P = 0.001), and (F) ( P = 0.775). A one‐way ANOVA test was used in (G) ( P = 0.772). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Cell Culture, Infection, Staining, shRNA, Expressing, Control, Marker, Transfection

    A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally infected at DIV4 with Nrxn1β‐FLAG, SALM1‐pHl, or SALM1 RAKA ‐pHl. Intracellular and surface stainings are shown for each construct. Bars = 5 μm. B Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for each construct. Arrows indicate examples of overlap between SALM1‐pHl and Nrxn1β‐FLAG clusters. Bars = 5 μm. C–E Average number (C), size (D), and intensity (E) ± SEM of surface Nrxn1β‐FLAG clusters. F Average ratio ± SEM of surface over total staining intensity for SALM1‐pHl and SALM1 RAKA ‐pHl. G Example images of neurites from DIV 11 sandwich‐cultured mouse excitatory hippocampal neurons lentivirally co‐infected at DIV4 with Nrxn1β‐FLAG and SALM1‐pHl or Nrxn1β‐FLAG and SALM1 RAKA ‐pHl. Surface stainings are shown for SALM1‐pHl and SALM1 RAKA ‐pHl. Total staining is shown for Nrxn1β‐FLAG. Bars = 5 μm. H–J Average number (H), size (I), and intensity (J) ± SEM of total (intracellular and surface) Nrxn1β‐FLAG clusters. Data information: For all graphs, the n is indicated in the bars and represents the total number of cells/total number of independent cultures. A one‐way ANOVA test with post hoc Bonferroni test was used for (C) ( P < 0.001), (F) ( P < 0.001), and (H) ( P = 0.987). Kruskal–Wallis tests with post hoc paired comparisons were used for (D) ( P < 0.001), (E) ( P < 0.001), (I) ( P = 0.06), and (J) ( P = 0.192). ns = not significant, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Cell Culture, Infection, Construct, Staining

    A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: A Example images of neurites from single isolated (autaptic) mouse excitatory hippocampal neurons stained for GFP and VGluT1. Cells were lentivirally infected with scrambled or SALM1 shRNA constructs at different time points (DIV7 or DIV9) and analyzed 7 days later (DIV14 or DIV16). At DIV7, cells were lentivirally infected with shRNA#2 + rSALM1, shRNA#2 + rSALM1 RAKA or with shRNA#2 + rSALM1ΔPDZ. Bars = 5 μm. B, C Average number of VGluT1 puncta per μm neurite ± SEM per neuron for DIV7→14 (B) and DIV9→16 (C). D, E Average intensity ± SEM of VGluT1 puncta per neuron for DIV7→14 (D) and DIV9→16 (E). F Electron micrographs of synapses from DIV14 autaptic hippocampal neurons lentivirally infected at DIV7 with scrambled, shRNA#1, or shRNA#2 (black, red and blue boxed images, respectively). Synaptic clefts are indicated by green arrows. Presynapses are localized above the synaptic cleft showing distinct vesicular structures; postsynapses are localized below the synaptic cleft. Bars = 100 nm. G Average number of synaptic vesicles per synapse ± SEM in electron micrographs. H Average size of the synaptic vesicle cluster per synapse ± SEM. I, J Average length of the presynaptic active zone (K) and the postsynaptic density (L) ± SEM per synapse. K Average number of membrane proximate vesicles ± SEM per synapse. Data information: For all graphs, numbers in bars indicate total number of neurons/total number of independent cultures. Kruskal–Wallis tests with post hoc paired comparisons were used for all data sets, P < 0.001 for (B, D, and G), P = 0.004 for (H), P = 0.349 for (C), P = 0.031 for (E), P = 0.879 for (I), P = 0.368 for (J), and P = 0.463 for (K). ns = not significant, * P < 0.05, ** P < 0.01, and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Isolation, Staining, Infection, shRNA, Construct, Membrane

    Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Patch‐clamp analysis (A–K) on single isolated mouse hippocampal neurons lentivirally infected with the indicated constructs at DIV7 and analyzed at DIV14‐15. A Example traces of EPSCs in control (black), shRNA#1 (red), shRNA#2 (blue), shRNA#2+rSALM1 (green), or shRNA#2+rSALM1 RAKA (orange) expressing cells. B Average evoked EPSC amplitudes ± SEM. Kruskal–Wallis ( P < 0.001). These experiments could not be performed with visual confirmation of lentiviral infection of rescue constructs, which typically is around 80%. Together with the high variability in evoked synaptic responses, this uncertain factor may explain that the average EPSC amplitudes are incompletely restored after SALM1 knockdown and that the RAKA mutant is not significantly different from the WT. C Example traces of mEPSCs from control (black), shRNA#1 (red), or shRNA#2 (blue) expressing cells. D, E Average mEPSC amplitudes ± SEM (D) or average frequencies ± SEM (E). Kruskal–Wallis ( P < 0.001 for E and P = 0.879 for D). F Average paired‐pulse ratios obtained using different intervals ± SEM. n = 20, n = 9, and n = 12 for scrambled, shRNA#1, and shRNA#2, respectively. G Average normalized EPSC response ± SEM upon 10 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.084). H Average normalized EPSC response ± SEM upon 40 Hz train stimulation. n = 20, n = 9, and n = 13 for scrambled, shRNA#1, and shRNA#2, respectively. Tau ± SEM is indicated in the graph for each condition and was not significant (Kruskal–Wallis, P = 0.897). I Cumulative EPSC responses to 40 Hz train stimulation. Green lines represent extrapolation used to determine RRP size. J Average RRP size ± SEM determined by back extrapolation of cumulative EPSCs in I (one‐way ANOVA with post hoc Games‐Howell, P = 0.007). K Average initial release probability (Pr) ± SEM per neuron calculated as the ratio of EPSC 0 /RRP size (Kruskal–Wallis, P = 0.347). M Average trace of the fluorescence intensity of SypHy in calcium phosphate transfected isolated hippocampal neurons expressing scrambled shRNA (black) or shRNA#2 (blue). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. N Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions. N, O Average SypHy intensity ± SEM upon NH 4 Cl exposure (N) or upon stimulation with 300 action potentials (O) (Mann–Whitney U ‐test, P = 0.02 for M and P = 0.03 for N). P Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Mann–Whitney U ‐test, P = 0.899). Q Average percentage of silent synapses ± SEM (Mann–Whitney U ‐test, P = 0.652). R Average trace of the fluorescence intensity of SypHy in lentivirally infected isolated hippocampal neurons expressing shRNA#2 (blue), shRNA#2+rSALM1 (green), shRNA#2+SALM1 RAKA (orange), or shRNA#2+SALM1ΔPDZ (gray). The timing of the 300 action potentials at 10 Hz stimulus and the exposure to NH 4 Cl are indicated in the graph. S Average SypHy intensity trace normalized to the maximum intensity upon NH 4 Cl superfusion for each of the given conditions in (Q). T, U Average percentage ± SEM rescue compared to rSALM1 upon NH 4 Cl exposure (U) or upon stimulation with 300 action potentials (T) (Kruskal–Wallis, P < 0.001 for T and U). V Normalized average SypHy intensity ± SEM upon 300 action potentials stimulation (Kruskal–Wallis, P = 0.06). Data information: For all graphs, numbers in bars indicate total number of cells/total number of independent experiments. ns = not significant, * P < 0.05, ** P < 0.01 and *** P < 0.001. Source data are available online for this figure.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques: Patch Clamp, Isolation, Infection, Construct, Control, shRNA, Expressing, Knockdown, Mutagenesis, Fluorescence, Transfection, MANN-WHITNEY

    Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Journal: The EMBO Journal

    Article Title: SALM 1 controls synapse development by promoting F‐actin/PIP2‐dependent Neurexin clustering

    doi: 10.15252/embj.2018101289

    Figure Lengend Snippet: Schematic model illustrating clustering of Neurexin by SALM1 in four steps. (1) SALM1 self‐clusters on cell membranes through direct homomeric cis ‐interactions. (2) SALM1 clusters recruit negatively charged PIP2 via electrostatic interactions with SALM1's polybasic domain. (3) PIP2 microdomains formed by SALM1 induce local F‐actin network formation. (4) Neurexin is recruited to SALM1 microdomains via F‐actin and PIP2. Together, the data in this study suggest a role for the Neurexin/SALM1/PIP2/F‐actin complex in synapse development and synaptic vesicle recruitment.

    Article Snippet: Hippocampal sections were immunolabeled using a primary antibody against SALM1 (ProSci Cat#5067, RRID:AB_10906317) diluted 1:10 in PBS supplemented with 0.1% BSA.

    Techniques:

    Generation and characterization of Lrfn2−/− mice. A, Strategy for the generation of Lrfn2−/− mice. B, PCR genotyping of Lrfn2−/− mice. HT, Heterozygous; C, Confirmation of Lrfn2 exon 2 deletion by qRT-PCR analysis of whole-brain mRNAs (P31). D, Lack of LRFN2 protein expression in the Lrfn2−/− brain (P21), as determined by immunoblot analysis of hippocampal lysates: total (Hp) and crude synaptosomal (Hp-P2). Untrans, Untransfected HEK293 cell lysates; SALM1-Myc, lysates of HEK293 cells transfected with SALM1-Myc. E, Normal gross morphology of the Lrfn2−/− brain (P28), as shown by staining for NeuN (a neuronal marker). Scale bar, 1 mm. F, Normal levels of other SALMs (SALM2-5), glutamate receptor subunits [AMPA (GluA1/A2), NMDA (GluN1/2A/2B), and metabotropic (mGluR5), and synaptic proteins (excitatory and inhibitory presynaptic and postsynaptic), compared with WT levels, as determined by immunoblot analyses of crude synaptosomal (P2) fractions from the WT and Lrfn2−/− hippocampus (P20–P23). Levels of the indicated proteins were normalized to those of α-tubulin for genotype comparisons. The dotted line indicates WT levels. n = 3 mice for WT and 4 mice for KO. NS, Student's t test (for additional details, see Figure 1-1).

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Generation and characterization of Lrfn2−/− mice. A, Strategy for the generation of Lrfn2−/− mice. B, PCR genotyping of Lrfn2−/− mice. HT, Heterozygous; C, Confirmation of Lrfn2 exon 2 deletion by qRT-PCR analysis of whole-brain mRNAs (P31). D, Lack of LRFN2 protein expression in the Lrfn2−/− brain (P21), as determined by immunoblot analysis of hippocampal lysates: total (Hp) and crude synaptosomal (Hp-P2). Untrans, Untransfected HEK293 cell lysates; SALM1-Myc, lysates of HEK293 cells transfected with SALM1-Myc. E, Normal gross morphology of the Lrfn2−/− brain (P28), as shown by staining for NeuN (a neuronal marker). Scale bar, 1 mm. F, Normal levels of other SALMs (SALM2-5), glutamate receptor subunits [AMPA (GluA1/A2), NMDA (GluN1/2A/2B), and metabotropic (mGluR5), and synaptic proteins (excitatory and inhibitory presynaptic and postsynaptic), compared with WT levels, as determined by immunoblot analyses of crude synaptosomal (P2) fractions from the WT and Lrfn2−/− hippocampus (P20–P23). Levels of the indicated proteins were normalized to those of α-tubulin for genotype comparisons. The dotted line indicates WT levels. n = 3 mice for WT and 4 mice for KO. NS, Student's t test (for additional details, see Figure 1-1).

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: Quantitative RT-PCR, Expressing, Western Blot, Transfection, Staining, Marker

    Distribution patterns of SALM1 mRNA and protein. A, In situ hybridization analysis of SALM1/Lrfn2 mRNA expression in mouse brain slices at different developmental stages using two independent probes against two different regions of SALM1/Lrfn2 mRNA. Scale bar, 10 mm. B, C, Distribution pattern of SALM1 protein, as determined by X-gal staining of coronal and sagittal sections of brain from male heterozygous (Lrfn2+/−) mice (P46). Scale bar, 1 mm.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Distribution patterns of SALM1 mRNA and protein. A, In situ hybridization analysis of SALM1/Lrfn2 mRNA expression in mouse brain slices at different developmental stages using two independent probes against two different regions of SALM1/Lrfn2 mRNA. Scale bar, 10 mm. B, C, Distribution pattern of SALM1 protein, as determined by X-gal staining of coronal and sagittal sections of brain from male heterozygous (Lrfn2+/−) mice (P46). Scale bar, 1 mm.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: In Situ Hybridization, Expressing, Staining

    Suppressed excitatory and inhibitory synaptic transmission in Lrfn2−/− mice. A, mEPSCs measured in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 17 cells from 4 WT mice and 15 cells from 6 KO mice. NS, Student's t test. B, mIPSCs in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 15, 3 for WT and 15, 3 for KO. *p < 0.05, NS, Mann–Whitney U test and Student's t test. C, sEPSCs in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 17, 5 for WT and 16, 5 for KO. NS, Student's t test. D, sIPSCs in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 18, 3 for WT and 16, 3 for KO. **p < 0.01, NS, Student's t test. E, mEPSCs in WT and Lrfn2−/− mPFC prelimbic layer II/III pyramidal neurons (P20–P23). n = 15, 3 for WT and 16, 3 for KO. **p < 0.01, NS, Mann–Whitney U test and Student's t test. F, mIPSCs in WT and Lrfn2−/− mPFC prelimbic layer II/III pyramidal neurons (P20–P23). n = 17, 3 for WT and 19, 3 for KO. NS, Mann–Whitney U test and Student's t test.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Suppressed excitatory and inhibitory synaptic transmission in Lrfn2−/− mice. A, mEPSCs measured in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 17 cells from 4 WT mice and 15 cells from 6 KO mice. NS, Student's t test. B, mIPSCs in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 15, 3 for WT and 15, 3 for KO. *p < 0.05, NS, Mann–Whitney U test and Student's t test. C, sEPSCs in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 17, 5 for WT and 16, 5 for KO. NS, Student's t test. D, sIPSCs in WT and Lrfn2−/− CA1 pyramidal neurons (P20–P23). n = 18, 3 for WT and 16, 3 for KO. **p < 0.01, NS, Student's t test. E, mEPSCs in WT and Lrfn2−/− mPFC prelimbic layer II/III pyramidal neurons (P20–P23). n = 15, 3 for WT and 16, 3 for KO. **p < 0.01, NS, Mann–Whitney U test and Student's t test. F, mIPSCs in WT and Lrfn2−/− mPFC prelimbic layer II/III pyramidal neurons (P20–P23). n = 17, 3 for WT and 19, 3 for KO. NS, Mann–Whitney U test and Student's t test.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: Transmission Assay, MANN-WHITNEY

    Decreased inhibitory synapse density in the Lrfn2−/− hippocampus. A, B, Decreased density of inhibitory, but not excitatory, synapses in the stratum radiatum region of the CA1 region in Lrfn2−/− mice (P21), as determined by EM analysis. Excitatory synapses were defined by PSD structures apposed to axon terminals (arrows and double arrowheads for nonperforated and perforated PSD, respectively) and inhibitory synapses were defined by PSDs apposed to presynaptic axon terminals with immunopositive GABA signals (arrows). Asterisks, GABA immunopositive axon terminals; d, postsynaptic dendrites; single arrowhead, GABA-immunopositive axon. Scale bar, 500 nm. n = 3 mice for WT and KO. **p < 0.01, NS, Student's t test.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Decreased inhibitory synapse density in the Lrfn2−/− hippocampus. A, B, Decreased density of inhibitory, but not excitatory, synapses in the stratum radiatum region of the CA1 region in Lrfn2−/− mice (P21), as determined by EM analysis. Excitatory synapses were defined by PSD structures apposed to axon terminals (arrows and double arrowheads for nonperforated and perforated PSD, respectively) and inhibitory synapses were defined by PSDs apposed to presynaptic axon terminals with immunopositive GABA signals (arrows). Asterisks, GABA immunopositive axon terminals; d, postsynaptic dendrites; single arrowhead, GABA-immunopositive axon. Scale bar, 500 nm. n = 3 mice for WT and KO. **p < 0.01, NS, Student's t test.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques:

    Lrfn2 mRNA is detected in both glutamatergic and GABAergic neurons. Expression of SALM1/Lrfn2 mRNA in glutamatergic and GABAergic neurons was determined by FISH. Coronal sections from mouse brains (male, 8 weeks) were triply stained for SALM1/Lrfn2 and Vglut1/2 (glutamatergic neuron markers) and Gad1/2 (GABAergic neuron markers) and counterstained with the nuclear dye DAPI. A mixture of two probes (Vglut1 + Vglut2 or Gad1 + Gad2) was used to label all glutamatergic or GABAergic neurons. The indicated cortical and hippocampal regions in the image at left were enlarged on the right to highlight the expression of Lrfn2 mRNA in both glutamatergic and GABAergic neurons; Lrfn2 expression in GABAergic neurons is further highlighted by arrows. Scale bar, 50 μm.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Lrfn2 mRNA is detected in both glutamatergic and GABAergic neurons. Expression of SALM1/Lrfn2 mRNA in glutamatergic and GABAergic neurons was determined by FISH. Coronal sections from mouse brains (male, 8 weeks) were triply stained for SALM1/Lrfn2 and Vglut1/2 (glutamatergic neuron markers) and Gad1/2 (GABAergic neuron markers) and counterstained with the nuclear dye DAPI. A mixture of two probes (Vglut1 + Vglut2 or Gad1 + Gad2) was used to label all glutamatergic or GABAergic neurons. The indicated cortical and hippocampal regions in the image at left were enlarged on the right to highlight the expression of Lrfn2 mRNA in both glutamatergic and GABAergic neurons; Lrfn2 expression in GABAergic neurons is further highlighted by arrows. Scale bar, 50 μm.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: Expressing, Staining

    Increased NMDAR-mediated synaptic transmission and suppressed NMDAR-dependent synaptic plasticity in the Lrfn2−/− hippocampus. A, Increased ratio of NMDAR/AMPAR-mediated synaptic transmission at Lrfn2−/− SC-CA1 synapses (P21–P24), measured as AMPA and NMDA EPSCs evoked at holding potentials of −70 and +40 mV, respectively. n = 9 slices from 8 mice for WT and 10 slices from 8 mice for KO. *p < 0.05, Student's t test. B, Normal basal transmission at Lrfn2−/− SC-CA1 synapses (P30–P35), as shown by the input/output relationship between fiber volley and fEPSP slopes. n = 8, 3 for WT and KO, repeated-measures two-way ANOVA. C, Normal paired-pulse facilitation at Lrfn2−/− SC-CA1 synapses (P30–P35), as shown by the relationship between interpulse intervals and fEPSP slopes. n = 8, 3 for WT and KO, repeated-measures two-way ANOVA. D, Increased NMDAR EPSCs at Lrfn2−/− SC-CA1 synapses (P22–P27), as shown by the relationship between stimulus intensities and initial slopes of NMDAR EPSCs. N = 18, 5 for WT and 16, 4 for KO. *p < 0.05, repeated-measures two-way ANOVA and one-way ANOVA. E, Normal TBS-LTP at Lrfn2−/− SC-CA1 synapses (P28–P36). Bar graphs represent average values during the last 10 min. n = 13, 5 for WT and 10, 6 for KO. NS, Student's t test. F, Suppressed HFS-LTP at Lrfn2−/− SC-CA1 synapses (P28–P36). Bar graphs represent average values during the last 10 min. n = 15, 7 for WT and 16, 7 for KO. *p < 0.05, Student's t test. G, Suppressed LFS-LTD at Lrfn2−/− SC-CA1 synapses (P16–P20). Bar graphs represent average values during the last 10 min. n = 13, 5 for WT and 11, 6 for KO. *p < 0.05, Student's t test.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Increased NMDAR-mediated synaptic transmission and suppressed NMDAR-dependent synaptic plasticity in the Lrfn2−/− hippocampus. A, Increased ratio of NMDAR/AMPAR-mediated synaptic transmission at Lrfn2−/− SC-CA1 synapses (P21–P24), measured as AMPA and NMDA EPSCs evoked at holding potentials of −70 and +40 mV, respectively. n = 9 slices from 8 mice for WT and 10 slices from 8 mice for KO. *p < 0.05, Student's t test. B, Normal basal transmission at Lrfn2−/− SC-CA1 synapses (P30–P35), as shown by the input/output relationship between fiber volley and fEPSP slopes. n = 8, 3 for WT and KO, repeated-measures two-way ANOVA. C, Normal paired-pulse facilitation at Lrfn2−/− SC-CA1 synapses (P30–P35), as shown by the relationship between interpulse intervals and fEPSP slopes. n = 8, 3 for WT and KO, repeated-measures two-way ANOVA. D, Increased NMDAR EPSCs at Lrfn2−/− SC-CA1 synapses (P22–P27), as shown by the relationship between stimulus intensities and initial slopes of NMDAR EPSCs. N = 18, 5 for WT and 16, 4 for KO. *p < 0.05, repeated-measures two-way ANOVA and one-way ANOVA. E, Normal TBS-LTP at Lrfn2−/− SC-CA1 synapses (P28–P36). Bar graphs represent average values during the last 10 min. n = 13, 5 for WT and 10, 6 for KO. NS, Student's t test. F, Suppressed HFS-LTP at Lrfn2−/− SC-CA1 synapses (P28–P36). Bar graphs represent average values during the last 10 min. n = 15, 7 for WT and 16, 7 for KO. *p < 0.05, Student's t test. G, Suppressed LFS-LTD at Lrfn2−/− SC-CA1 synapses (P16–P20). Bar graphs represent average values during the last 10 min. n = 13, 5 for WT and 11, 6 for KO. *p < 0.05, Student's t test.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: Transmission Assay

    Normal locomotion and anxiety-like behavior in Lrfn2−/− mice. A, B, Normal locomotor activity and anxiety-like behavior of Lrfn2−/− mice (3 months) in open-field tests at two different light intensities (110 and 0 lux), as shown by distance moved and time spent in the center region of the open-field arena. n = 13 mice for WT and 14 mice for KO (110 lux), and 13 for WT and 16 for KO (0 lux). NS, repeated-measures two-way ANOVA and Student's t test. C, Normal locomotor activity of Lrfn2−/− mice (2 months) in LABORAS cages, where mouse movements were monitored for 3 consecutive days. n = 13 for WT and 16 for KO. NS, repeated-measures two-way ANOVA. D, Normal anxiety-like behavior of Lrfn2−/− mice (4 months) in the elevated plus-maze test. n = 14 for WT and 17 for KO. NS, Student's t test. E, Normal anxiety-like behavior of Lrfn2−/− mice (4 months) in the light/dark test. n = 14 for WT and 16 for KO. NS, Student's t test.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Normal locomotion and anxiety-like behavior in Lrfn2−/− mice. A, B, Normal locomotor activity and anxiety-like behavior of Lrfn2−/− mice (3 months) in open-field tests at two different light intensities (110 and 0 lux), as shown by distance moved and time spent in the center region of the open-field arena. n = 13 mice for WT and 14 mice for KO (110 lux), and 13 for WT and 16 for KO (0 lux). NS, repeated-measures two-way ANOVA and Student's t test. C, Normal locomotor activity of Lrfn2−/− mice (2 months) in LABORAS cages, where mouse movements were monitored for 3 consecutive days. n = 13 for WT and 16 for KO. NS, repeated-measures two-way ANOVA. D, Normal anxiety-like behavior of Lrfn2−/− mice (4 months) in the elevated plus-maze test. n = 14 for WT and 17 for KO. NS, Student's t test. E, Normal anxiety-like behavior of Lrfn2−/− mice (4 months) in the light/dark test. n = 14 for WT and 16 for KO. NS, Student's t test.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: Activity Assay

    Suppressed USVs in pups, but normal social interaction, communication, and repetitive behaviors in adult Lrfn2−/− mice. A, Normal social approach and social novelty recognition in Lrfn2−/− mice (3–4 months) in the 3-chamber test, as shown by time spent in the chamber and sniffing. n = 14 mice for WT and 17 mice for KO. *p < 0.05, **p < 0.01, ***p < 0.001, paired t test and Wilcoxon test. B, Normal social interaction in Lrfn2−/− mice (3–4 months) in the direct social interaction test. n = 7 WT mouse pairs and 8 KO mouse pairs. NS, Student's t test. C, Normal USVs of male Lrfn2−/− mice (4–5 months) induced by encounter with a female. n = 13 mice for WT and 16 mice for KO. NS, Student's t test. D, Normal pup retrieval in female Lrfn2−/− mice (3–5 months) induced by WT pups (P1) separated from their mothers, as shown by the time taken to retrieve first, second, and third pups. n = 23 mice for WT and 21 mice for KO. NS, Mann–Whitney U test. E, Suppressed USVs in Lrfn2−/− pups (P4, P6, P8, and P10) separated from their mothers, as shown by number of calls and individual call duration. For P4, n = 16 mice for WT and 22 mice for KO; for P6, n = 17 for WT and 21 for KO; for P8, n = 11 for WT and 21 for KO; for P10, n = 14 for WT and 21 for KO. *p < 0.05, **p < 0.01, NS, Student's t test and Mann–Whitney U test. F, G, Normal repetitive behaviors of Lrfn2−/− mice (3–4 months), as shown by self-grooming, digging, and marble burying. For digging and grooming, n = 14 mice for WT and 17 mice for KO; for marble burying, n = 13 for WT and 16 for KO. NS, Student's t test and Mann–Whitney U test. H, Normal motor coordination of Lrfn2−/− mice (4–5 months) in the rotarod test. n = 14 mice for WT and 17 mice for KO. NS, repeated-measures two-way ANOVA.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Suppressed USVs in pups, but normal social interaction, communication, and repetitive behaviors in adult Lrfn2−/− mice. A, Normal social approach and social novelty recognition in Lrfn2−/− mice (3–4 months) in the 3-chamber test, as shown by time spent in the chamber and sniffing. n = 14 mice for WT and 17 mice for KO. *p < 0.05, **p < 0.01, ***p < 0.001, paired t test and Wilcoxon test. B, Normal social interaction in Lrfn2−/− mice (3–4 months) in the direct social interaction test. n = 7 WT mouse pairs and 8 KO mouse pairs. NS, Student's t test. C, Normal USVs of male Lrfn2−/− mice (4–5 months) induced by encounter with a female. n = 13 mice for WT and 16 mice for KO. NS, Student's t test. D, Normal pup retrieval in female Lrfn2−/− mice (3–5 months) induced by WT pups (P1) separated from their mothers, as shown by the time taken to retrieve first, second, and third pups. n = 23 mice for WT and 21 mice for KO. NS, Mann–Whitney U test. E, Suppressed USVs in Lrfn2−/− pups (P4, P6, P8, and P10) separated from their mothers, as shown by number of calls and individual call duration. For P4, n = 16 mice for WT and 22 mice for KO; for P6, n = 17 for WT and 21 for KO; for P8, n = 11 for WT and 21 for KO; for P10, n = 14 for WT and 21 for KO. *p < 0.05, **p < 0.01, NS, Student's t test and Mann–Whitney U test. F, G, Normal repetitive behaviors of Lrfn2−/− mice (3–4 months), as shown by self-grooming, digging, and marble burying. For digging and grooming, n = 14 mice for WT and 17 mice for KO; for marble burying, n = 13 for WT and 16 for KO. NS, Student's t test and Mann–Whitney U test. H, Normal motor coordination of Lrfn2−/− mice (4–5 months) in the rotarod test. n = 14 mice for WT and 17 mice for KO. NS, repeated-measures two-way ANOVA.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: MANN-WHITNEY

    Normal learning and memory in Lrfn2−/− mice. A, Normal novel object recognition memory in Lrfn2−/− mice (2–3 months). n = 17 mice for WT and 18 mice for KO. NS, Student's t test. B, Normal displaced object recognition memory in Lrfn2−/− mice (2–3 months). n = 16 mice for WT and KO. NS, Student's t test. C–H, Normal learning and memory in Lrfn2−/− mice (3–4 months) in the learning, probe, and reversal phases of the Morris water maze test. Pre-T, Previous target. n = 9 mice for WT and 10 mice for KO. *p < 0.05, NS, repeated-measures two-way ANOVA, Student's t test, and Mann–Whitney U test. I–K, Normal fear learning and memory in Lrfn2−/− mice (4–5 months). Mice with acquired fear memory in a spatial context combined with a sound cue (I) were tested for contextual fear memory 24 h after training (J) and for cued fear memory 28 h after training (K). n = 14 mice for WT and 17 mice for KO. NS, repeated-measures two-way ANOVA, Student's t test, and Mann–Whitney U test.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Normal learning and memory in Lrfn2−/− mice. A, Normal novel object recognition memory in Lrfn2−/− mice (2–3 months). n = 17 mice for WT and 18 mice for KO. NS, Student's t test. B, Normal displaced object recognition memory in Lrfn2−/− mice (2–3 months). n = 16 mice for WT and KO. NS, Student's t test. C–H, Normal learning and memory in Lrfn2−/− mice (3–4 months) in the learning, probe, and reversal phases of the Morris water maze test. Pre-T, Previous target. n = 9 mice for WT and 10 mice for KO. *p < 0.05, NS, repeated-measures two-way ANOVA, Student's t test, and Mann–Whitney U test. I–K, Normal fear learning and memory in Lrfn2−/− mice (4–5 months). Mice with acquired fear memory in a spatial context combined with a sound cue (I) were tested for contextual fear memory 24 h after training (J) and for cued fear memory 28 h after training (K). n = 14 mice for WT and 17 mice for KO. NS, repeated-measures two-way ANOVA, Student's t test, and Mann–Whitney U test.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: MANN-WHITNEY

    Enhanced acoustic startle, but normal prepulse inhibition and susceptibility to induced seizure, in Lrfn2−/− mice. A, Enhanced acoustic startle responses of Lrfn2−/− mice (4–5 months) in a high loudness range (>110 dB). n = 20 mice for WT and 24 mice for KO. **p < 0.01, ***p < 0.001, repeated-measures two-way ANOVA with Bonferroni test. B, Normal prepulse inhibition in Lrfn2−/− mice (4–5 months). n = 14 mice for WT and 17 mice for KO. Repeated-measures two-way ANOVA. C, Normal susceptibility to a seizure induced by PTZ (40 mg/kg, i.p.) in Lrfn2−/− mice (5–6 months). The numbers in pie charts indicate the proportions of mice that reached the indicated stages of seizure at the end of the test (10 min). n = 13 mice for WT and 16 mice for KO. NS, χ2 analysis.

    Journal: The Journal of Neuroscience

    Article Title: Lrfn2-Mutant Mice Display Suppressed Synaptic Plasticity and Inhibitory Synapse Development and Abnormal Social Communication and Startle Response

    doi: 10.1523/JNEUROSCI.3321-17.2018

    Figure Lengend Snippet: Enhanced acoustic startle, but normal prepulse inhibition and susceptibility to induced seizure, in Lrfn2−/− mice. A, Enhanced acoustic startle responses of Lrfn2−/− mice (4–5 months) in a high loudness range (>110 dB). n = 20 mice for WT and 24 mice for KO. **p < 0.01, ***p < 0.001, repeated-measures two-way ANOVA with Bonferroni test. B, Normal prepulse inhibition in Lrfn2−/− mice (4–5 months). n = 14 mice for WT and 17 mice for KO. Repeated-measures two-way ANOVA. C, Normal susceptibility to a seizure induced by PTZ (40 mg/kg, i.p.) in Lrfn2−/− mice (5–6 months). The numbers in pie charts indicate the proportions of mice that reached the indicated stages of seizure at the end of the test (10 min). n = 13 mice for WT and 16 mice for KO. NS, χ2 analysis.

    Article Snippet: SALM1 (2022) guinea pig polyclonal antibodies were generated using the last 30 aa of mouse SALM1 as immunogen (NGMLLPFEESDLVGARGTFGSSEWVMESTV).

    Techniques: Inhibition