UNC-13 is required for synaptic vesicle fusion in C. elegans

Nat Neurosci. 1999 Nov;2(11):959-64. doi: 10.1038/14755.

Abstract

We analyzed the synaptic physiology of unc-13 mutants in the nematode C. elegans. Mutants of unc-13 had normal nervous system architecture, and the densities of synapses and postsynaptic receptors were normal at the neuromuscular junction. However, the number of synaptic vesicles at neuromuscular junctions was two- to threefold greater in unc-13 mutants than in wild-type animals. Most importantly, evoked release at both GABAergic and cholinergic synapses was almost absent in unc-13 null alleles, as determined by whole-cell, voltage-clamp techniques. Although mutant synapses had morphologically docked vesicles, these vesicles were not competent for release as assayed by spontaneous release in calcium-free solution or by the application of hyperosmotic saline. These experiments support models in which UNC-13 mediates either fusion of vesicles during exocytosis or priming of vesicles for fusion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / physiology*
  • Caenorhabditis elegans Proteins*
  • Carrier Proteins
  • Helminth Proteins / genetics
  • Helminth Proteins / physiology*
  • Mutation
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / physiology*
  • Neuromuscular Junction / physiology
  • Synaptic Transmission / physiology
  • Synaptic Vesicles / physiology*

Substances

  • Caenorhabditis elegans Proteins
  • Carrier Proteins
  • Helminth Proteins
  • Nerve Tissue Proteins
  • phorbol ester binding protein