title: Synaptic vesicle mobility and presynaptic F-actin are disrupted in a N-ethylmaleimide-sensitive factor allele of Drosophila.
abstract: N-ethylmaleimide sensitive factor (NSF) can dissociate the soluble NSF attachment receptor (SNARE) complex, but NSF also participates in other intracellular trafficking functions by virtue of SNARE-independent activity. Drosophila that express a neural transgene encoding a dominant-negative form of NSF2 show an 80% reduction in the size of releasable synaptic vesicle pool, but no change in the number of vesicles in nerve terminal boutons. 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 nerve terminal boutons of Drosophila NSF2 mutant larvae. Subsequent analysis revealed a decrease of filamentous actin in both NSF2 dominant-negative and loss-of-function mutants. Lastly, actin-filament disrupting drugs also decrease vesicle movement. We conclude that a factor contributing to the NSF mutant phenotype is a reduction in vesicle mobility, which is associated with decreased presynaptic F-actin. Our data are consistent with a model in which actin filaments promote vesicle mobility and suggest that NSF participates in establishing or maintaining this population of actin.
authors.affiliation: Department of Biology and Computer Science, University of Toronto, Mississauga, Ontario, Canada.
authors.forename: Paula
authors.initials: P
authors.lastname: Nunes
authors.forename: Nicola
authors.initials: N
authors.lastname: Haines
authors.forename: Venkat
authors.initials: V
authors.lastname: Kuppuswamy
authors.forename: David J
authors.initials: DJ
authors.lastname: Fleet
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Stewart
mesh_terms: D000199:Actins / Q000378:metabolism*; D000483:Alleles; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D004330:Drosophila / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D007814:Larva / Q000166:cytology / Q000187:drug effects; D008387:Marine Toxins / Q000494:pharmacology; D052066:N-Ethylmaleimide-Sensitive Proteins / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D053778:Thiazolidines / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D008387:Marine Toxins; C498738:Nsf2 protein, Drosophila; D011993:Recombinant Fusion Proteins; D053778:Thiazolidines; C086235:swinholide A; D052066:N-Ethylmaleimide-Sensitive Proteins; C037067:latrunculin A