Membrane proximal lysosomes are the major vesicles responsible for calcium-dependent exocytosis in nonsecretory cells.
Similar to its role in secretory cells, calcium triggers exocytosis in nonsecretory cells. This calcium-dependent exocytosis is essential for repair of membrane ruptures. Using total internal reflection fluorescence microscopy, we observed that many organelles implicated in this process, including ER, post-Golgi vesicles, late endosomes, early endosomes, and lysosomes, were within 100 nm of the plasma membrane (in the evanescent field). However, an increase in cytosolic calcium led to exocytosis of only the lysosomes. The lysosomes that fused were predominantly predocked at the plasma membrane, indicating that calcium is primarily responsible for fusion and not recruitment of lysosomes to the cell surface.
Jaiswal
Jyoti K
JK
Laboratory of Cellular Biophysics, Rockefeller University, New York, NY 10021, USA.
Andrews
Norma W
NW
Simon
Sanford M
SM
D000818:Animals; D015415:Biomarkers; D000001:Calcimycin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D006224:Cricetinae; D005089:Exocytosis / Q000502:physiology*; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D007476:Ionophores / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology; D051379:Mice; D018613:Microscopy, Confocal; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D005456:Fluorescent Dyes; D007476:Ionophores; D011993:Recombinant Fusion Proteins; D000001:Calcimycin; D002118:Calcium