Intracellular trafficking of VAMP4-positive vesicles and lysosomes in vivo. VAMP4-positive vesicles and lysosomes were labeled with EGFP-tagged VAMP4 (green) and mCherry-tagged LAMP1 (red), respectively. The two plasmids were simultaneously transfected into INS-1 cells. 48 h after transfection, live-cell imaging was performed at 37°C in an atmosphere with 5% CO2 using a Delta Vision OMX V3 system in the wide-field mode with an exposure time of 0.01 s at each frame and an interval time of 0.5 s for 1 min. The playback speed of video was 30 frames per second. The movie shows that VAMP4-labeled signals fuse with lysosomes and diffuse on the lysosomal membrane (indicated by arrows), which reveals that VAMP4-positive vesicles are transported to and fuse with lysosomes.
