Journal: bioRxiv
Article Title: Recruitment of the SNX17-Retriever recycling pathway regulates synaptic function and plasticity
doi: 10.1101/2023.02.20.529299
Figure Lengend Snippet: β1-integrin is a SNX17 cargo in neurons and plays a role in dendritic spine density. (A) DIV11 rat cortical neurons were infected with lentiviruses carrying scramble or SNX17 shRNAs, and the surface levels of β1-integrin were determined at DIV17 using a surface biotinylation assay. SNX17 knockdown was validated by western blotting of the lysate, and GAPDH was used as a loading control. (B) The levels of surface β1-integrin protein were quantified and normalized to total β1-integrin levels (lysate). Data are expressed as percentage of ctrl-shRNA (ctrl-shRNA: 100%, SNX17-shRNA: 57.630 ± 3.058%). N=4 independent experiments. Statistical significance was determined using unpaired two-tailed Student’s t-test, ****p<0.001. Error bars are SEM. (C) Representative confocal images of surface β1-integrin levels of DIV17 hippocampal neurons that were infected at DIV11 with lentiviruses carrying either ctrl-shRNA or SNX17-shRNA. Neurons were treated in the presence or absence of cLTP and live labeled with an anti-surface ß1-integrin antibody for 15 min, followed by fixation and immunostaining for MAP2. Scale bar, 5 µm. (D) The intensity of ß1-integrin in the first 50 µm of secondary dendrites was quantified, and values were normalized to crtl-shRNA. ctrl-shRNA: 1.000 ± 0.038, N=32 neurons; ctrl-shRNA cLTP: 1.139 ± 0.039, N=29 neurons; SNX17-shRNA: 0.839 ± 0.040, N=28 neurons; SNX17-shRNA cLTP: 0.786 ± 0.035, N=28 neurons. 3 independent experiments. Data were analyzed by one-way ANOVA with Tukey’s post hoc test, *p<0.05. Error bars are SEM. (E) Validation of a shRNA clone (V2LMM_39157, Horizon Discovery) to knock-down rat ITGB1. pGIPZ scrambled non-target (RHS4346, Horizon Discovery) was used as a control. HEK293 cells stably expressing the tet repressor (TR-HEK293) were either transfected with control-shRNA or ITGB1-shRNA in the absence or presence of eGFP or ITGB1-GFP, as indicated. 5-days post-infection, cells were treated with 1 μg/ml of doxycycline to promote the expression of eGFP or ITGB1-GFP. 24 hours later, extracts were generated and analyzed by western blot. (F) Representative confocal images of dendritic spines in DIV16 hippocampal neurons transfected at DIV12 with eGFP (filler) and either ctrl-shRNA or ITGB1-shRNA. Scale bar, 5 µm. treated with either β1-integrin blocking or iso type control antibodies 24 hours before fixation. Scale bar, 5 µm. (G) The numbers of dendritic spines in the first 30 μm of secondary dendrites were quantified. ctrl-shRNA: 0.705 ± 0.044, N=31 neurons; ITGB1-shRNA: 0.505 ± 0.043, N=33 neurons. Statistical significance was determined using unpaired two-tailed Student’s t-test, **p<0.01. Error bars are SEM. (H) Hippocampal neurons were transfected at DIV12 with eGFP (filler) and either ctrl-shRNA or SNX17-shRNA. Neurons were treated with either β1-integrin blocking or isotype control antibodies 24 hours before fixation at DIV16. The number of dendritic spines in the first 30 μm of secondary dendrites was quantified. ctrl-shRNA + isotype ctrl: 0.689 ± 0.030, N=26 neurons; ctrl-shRNA +β1-integrin blocking: 0.451 ± 0.021, N=27 neurons; SNX17-shRNA + isotype ctrl: 0.385 ± 0.026, N=28 neurons; SNX17-shRNA +β1-integrin blocking: 0.387 ± 0.020, N=26 neurons,. Statistical significance was determined using one-way ANOVA with Tukey’s post hoc test, ****p<0.001. Error bars are SEM
Article Snippet: Primary antibodies used included SNX17 rabbit pAb (1:1000, HPA043867, Atlas Antibodies), SNX17 mouse mAb, VPS35L rabbit pAb (1:1000, Daniel D. Billadeau), COMMD1 rabbit pAb (1:1000, 11938-1-AP, Proteintech), GFP rabbit mAb (1:1000, Ab32146, Abcam), mouse/rabbit Integrin β1 goat pAb (1:1000, AF2405, R&D Systems) and GAPDH rabbit mAb (1:2000, 2118, Cell Signaling).
Techniques: Infection, Surface Biotinylation Assay, Knockdown, Western Blot, Control, shRNA, Two Tailed Test, Labeling, Immunostaining, Biomarker Discovery, Stable Transfection, Expressing, Transfection, Generated, Blocking Assay