Figure 7.
VAMP3 Is Required for Fusion of Vesicles Carrying mATG9 and ATG16L1
(A) HeLa cells transfected with control, VAMP3 siRNA for 4 days were transfected during the last 20 hr with mStrawberry-ATG16L1 and labeled for mATG9. The correlation between mATG9 and ATG16L1 was quantified (Pearson’s coefficient). Error bar, SEM. ∗∗∗p < 0.001.
(B) HeLa cells were transfected with control or VAMP3 siRNA and then with mStrawberry-ATG16, and 5 min movies were recorded. Homotypic fusion events between mStrawberry-ATG16 vesicles were assessed in control and VAMP3 knockdown cells. Error bar, SEM. NS, not significant.
(C) In vitro fusion assay of ATG16L1 and mATG9 vesicles. HeLa cells were transfected with control or VAMP3 siRNA for 4 days separately and, on the fourth day, either transfected with mStrawberry-ATG16L1 or ATG9L1-pEGFP. PNS of cells expressing the two constructs were mixed for 1 hr at 37C° and observed by confocal microscopy. Histogram shows the correlation of vesicles carrying ATG16L1 that fuse with vesicles carrying mATG9 (Pearson’s coefficient). Error bar, SEM. ∗∗∗p < 0.001. The total number of structures per field (ATG16L1 and ATG9L1) is not significantly different in the control and KD samples (control, 37 ± 3; VAMP3 KD, 45 ± 3; ± SEM; p = 0.106).
(D) Schematic diagram of mATG9 and ATG16L1 itineraries pertinent to their heterotypic fusion and autophagosome formation.