Journal: The Journal of Cell Biology
Article Title: A Rab1 interactome illuminates a dual role in autophagy and membrane trafficking
doi: 10.1083/jcb.202507084
Figure Lengend Snippet: The Rab1A – OPTN interaction is required for mitophagy. (A) GUV-binding assay using GTP- or GDP-locked Rab1A bound to GUVs before applying GFP-OPTN WT or Rab1-binding mutant. Each large datapoint in the graph depicts the average mean fluorescence intensity of GFP-OPTN WT or Rab1-binding mutant on a selection of GUV membrane and represents an independent experiment ( n = 3), with smaller gray datapoints representing all the technical replicates (AU, arbitrary units). The mean ± SD is indicated. ***P < 0.001 (one-way ANOVA with Tukey’s multiple comparisons test). (B) Representative immunoblot of Rab1 interactors following MitoID in HEK293A cells where Rab1A MitoID constructs (detected using anti HA) and 3xFlag-OPTN proteins (detected using anti Flag) were transiently expressed. Endogenous CALCOCO1 was used as a positive control. Each datapoint in the graph represents the normalized ratio between the OPTN and MitoID construct immunoblot intensities and depicts an independent experiment ( n = 3). The mean ± SD is indicated. ****P < 0.0001; (one-way ANOVA with Dunnett’s multiple comparisons test). (C) Schematic of the overall structure of OPTN, with different binding regions annotated (TBK1, TBK1-binding domain; Rab1, the Rab1-binding domain; LIR, LC3 interacting-region; UBAN, ubiquitin-binding domain in ABIN proteins and NEMO; ZF: zinc finger domain). The predicted coiled-coil regions of OPTN are also illustrated as predicted by MARCOIL . (D) Representative immunoblot and in-gel fluorescence analysis of cell lysates of pentaKO HeLa cells stably expressing pSu9-HaloTag-mGFP and Parkin and either mock transfected (/) or expressing OPTN WT, or the mutant constructs OPTN Rab1, OPTN Ub (unable to bind ubiquitin), or OPTN LIR (unable to bind ATG8/LC3 family proteins). To assay mitophagy, cells were pulse-labelled with 100 nM TMR HaloTag ligand and incubated in medium containing 1 μM oligomycin and 5 μM antimycin for 24 h to induce mitophagy (O + A). Each datapoint in the bar graph is an independent experiment representing the normalized ratio between the free HaloTag and the combined pSu9-HaloTag-mGFP + free HaloTag fluorescence intensities ( n = 3). The mean ± SD is indicated. ****P < 0.001 (one-way ANOVA with Tukey’s multiple comparisons test). Source data are available for this figure: .
Article Snippet: Antibodies used in this study were RABEP1 (610676; BD Transduction Laboratories, RRID: AB_398003), PPP1R37 (HPA041500; Atlas Antibodies, RRID: AB_10795122), CLEC16A (26257-1-AP; Proteintech, RRID: AB_2880449), Rab1A (13075; Cell Signaling Technologies, RRID: AB_2665537), HA (3F10; Roche, RRID: AB_2314622), TOM20 (ab56783; Abcam, RRID: AB_945896), Flag M2 (F1804; Sigma-Aldrich, RRID), CALCOCO1 (HPA038313; Atlas Antibodies, RRID: AB_10675794), GAPDH (60004-1; Proteintech, RRID: AB_2107436), OPTN (70928; Cell Signaling Technologies, RRID: AB_3073769), and α-tubulin (YL1/2, RRID: AB_305328).
Techniques: Binding Assay, Mutagenesis, Fluorescence, Selection, Membrane, Western Blot, Construct, Positive Control, Ubiquitin Proteomics, Stable Transfection, Expressing, Transfection, Incubation