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Effects of wortmannin and latrunculin A on slow endocytosis at the frog neuromuscular junction
Author(s) -
Richards D. A.,
Rizzoli S. O.,
Betz W. J.
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.062158
Subject(s) - wortmannin , microbiology and biotechnology , actin cytoskeleton , kiss and run fusion , biology , synaptic vesicle , endocytic cycle , exocytosis , bulk endocytosis , endocytosis , vesicle , synaptic vesicle recycling , cytoskeleton , phosphatidylinositol , signal transduction , biochemistry , receptor , cell , membrane , secretion
Phosphoinositides are key regulators of synaptic vesicle cycling and endocytic traffic; the actin cytoskeleton also seems to be involved in modulating these processes. We investigated the effects of perturbing phosphoinositide signalling and actin dynamics on vesicle cycling in frog motor nerve terminals, using fluorescence and electron microscopy, and electrophysiology. Antibody staining for β‐actin revealed that actin surrounds but does not overlap with synaptic vesicle clusters. Latrunculin A, which disrupts actin filaments by binding actin monomers, and wortmannin, an inhibitor of phosphatidyl inositol‐3‐kinase (PI3‐kinase), each disrupted the pattern of presynaptic actin staining, but not vesicle clusters in resting terminals. Latrunculin A, but not wortmannin, also reduced vesicle mobilization and exocytosis. Both drugs inhibited the stimulation‐induced uptake of the styryl dye FM1‐43 and blocked vesicle reformation from internalized membrane objects after tetanic stimulation. These results are consistent with a role of PI3‐kinase and the actin cytoskeleton in the slow pathway of vesicle endocytosis, used primarily by reserve pool vesicles.