TIRFM analysis reveals exocytosis of post-Golgi vesicles from both daughter cells at the cleavage furrow during cytokinesis. (A) BSC1 cells expressing VSVG-YFP were imaged by TIRFM at 1.67 frames/s (Video 5). Paths of five vesicles are shown from each daughter cell as they enter the furrow region. Dashed rectangle indicates enlarged regions shown in D and E. (B) The number of exocytic events in the furrow and cell body was manually determined and displayed as number of events per μm2 per minute. Error bars show SEM. (C) Docking times (in seconds) of individual vesicles before fusion with plasma membrane were determined in cell body and cleavage furrow regions. Error bars show SEM. (D and E) Gallery of enlarged TIRFM images from A shows exocytic fusion of vesicles on both sides of midbody region (red and green arrowheads). Dashed circles indicate sites of exocytic fusion. (F) Working model for membrane trafficking during cytokinesis. Individual post-Golgi (1) vesicles (green) from both daughter cells traffic to furrow region (2) where they accumulate (3) and remain distinct from lysosomes (yellow), early endosomes (dark blue), and recycling endosomes (red). Post-Golgi vesicles from both daughter cells can exocytose (4) at the furrow (asterisks). Golgi, green; nucleus, light blue.
