Nunes, P., Haines, N., Kuppuswamy, V., Fleet, D.J. and Stewart, B.
Presynaptic f-Actin promotes synaptic vesicle mobility and is
disrupted by an NSF allele in Drosophila.
Molecular Biology of the Cell,
N-ethylmaleimide sensitive factor (NSF) can dissociate the SNARE complex
but other studies indicate NSF also has SNARE-independent activity. We
previously showed that Drosophila larvae with a transgene encoding a
mutated form of NSF2 have the same number of synaptic vesicles in
nerve terminal boutons but there is an 80% reduction in the number
of releasable vesicles. Here we tested the hypothesis that vesicles in
the NSF2 mutant terminal are less mobile. Using a combination of genetics,
pharmacology, and imaging we find a substantial reduction in vesicle
mobility within the boutons of Drosophila NSF2 mutant larvae. Further
analyses indicate that there is a corresponding reduction of filamentous
actin in the NSF2 mutant and the effect on vesicle mobility is mimicked
by an actin filament-severing compound. These data are consistent with
a model in which actin filaments promote vesicle mobility and that NSF
is important to establish or maintain this population of actin.
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