[HTML][HTML] Synaptotagmin VII restricts fusion pore expansion during lysosomal exocytosis

JK Jaiswal, S Chakrabarti, NW Andrews… - PLoS biology, 2004 - journals.plos.org
JK Jaiswal, S Chakrabarti, NW Andrews, SM Simon
PLoS biology, 2004journals.plos.org
Synaptotagmin is considered a calcium-dependent trigger for regulated exocytosis. We
examined the role of synaptotagmin VII (Syt VII) in the calcium-dependent exocytosis of
individual lysosomes in wild-type (WT) and Syt VII knockout (KO) mouse embryonic
fibroblasts (MEFs) using total internal reflection fluorescence microscopy. In WT MEFs, most
lysosomes only partially released their contents, their membrane proteins did not diffuse into
the plasma membrane, and inner diameters of their fusion pores were smaller than 30 nm. In …
Synaptotagmin is considered a calcium-dependent trigger for regulated exocytosis. We examined the role of synaptotagmin VII (Syt VII) in the calcium-dependent exocytosis of individual lysosomes in wild-type (WT) and Syt VII knockout (KO) mouse embryonic fibroblasts (MEFs) using total internal reflection fluorescence microscopy. In WT MEFs, most lysosomes only partially released their contents, their membrane proteins did not diffuse into the plasma membrane, and inner diameters of their fusion pores were smaller than 30 nm. In Syt VII KO MEFs, not only was lysosomal exocytosis triggered by calcium, but all of these restrictions on fusion were also removed. These observations indicate that Syt VII does not function as the calcium-dependent trigger for lysosomal exocytosis. Instead, it restricts the kinetics and extent of calcium-dependent lysosomal fusion.
PLOS