Molecular mechanisms determining conserved properties of short-term synaptic depression revealed in NSF and SNAP-25 conditional mutants.
Current models of synaptic vesicle trafficking implicate a core complex of proteins comprised of N-ethylmaleimide-sensitive factor (NSF), soluble NSF attachment proteins (SNAPs), and SNAREs in synaptic vesicle fusion and neurotransmitter release. Despite this progress, major challenges remain in establishing the in vivo functions of these proteins and their roles in determining the physiological properties of synapses. The present study employs glutamatergic adult neuromuscular synapses of Drosophila, which exhibit conserved properties of short-term synaptic plasticity with respect to mammalian glutamatergic synapses, to address these issues through genetic analysis. Our findings establish an in vivo role for SNAP-25 in synaptic vesicle priming, and support a zippering model of SNARE function in this process. Moreover, these studies define the contribution of SNAP-25-dependent vesicle priming to the detailed properties of short-term depression elicited by paired-pulse (PP) and train stimulation. In contrast, NSF is shown here not to be required for WT PP depression, but to be critical for maintaining neurotransmitter release during sustained stimulation. In keeping with this role, disruption of NSF function results in activity-dependent redistribution of the t-SNARE proteins, SYNTAXIN and SNAP-25, away from neurotransmitter release sites (active zones). These findings support a role for NSF in replenishing active zone t-SNAREs for subsequent vesicle priming, and provide new insight into the spatial organization of SNARE protein cycling during synaptic activity. Together, the results reported here establish in vivo contributions of SNAP-25 and NSF to synaptic vesicle trafficking and define molecular mechanisms determining conserved functional properties of short-term depression.
Kawasaki
Fumiko
F
Department of Biology and Center for Molecular and Cellular Neuroscience, Pennsylvania State University, University Park, PA 16802, USA.
Ordway
Richard W
RW
D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D007150:Immunohistochemistry; D009154:Mutation; D052066:N-Ethylmaleimide-Sensitive Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology; D050765:Qa-SNARE Proteins / Q000378:metabolism; D050600:SNARE Proteins / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism / Q000502:physiology*; D050825:Synaptosomal-Associated Protein 25 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors
D029721:Drosophila Proteins; D050765:Qa-SNARE Proteins; D050600:SNARE Proteins; C494207:Snap25 protein, Drosophila; D050825:Synaptosomal-Associated Protein 25; C498732:comt protein, Drosophila; D052066:N-Ethylmaleimide-Sensitive Proteins
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