Munc13-1 and Munc18-1 together prevent NSF-dependent de-priming of synaptic vesicles

Nat Commun. 2017 Jun 21;8:15915. doi: 10.1038/ncomms15915.

Abstract

Synaptic transmission requires a stable pool of release-ready (primed) vesicles. Here we show that two molecules involved in SNARE-complex assembly, Munc13-1 and Munc18-1, together stabilize release-ready vesicles by preventing de-priming. Replacing neuronal Munc18-1 by a non-neuronal isoform Munc18-2 (Munc18-1/2SWAP) supports activity-dependent priming, but primed vesicles fall back into a non-releasable state (de-prime) within seconds. Munc13-1 deficiency produces a similar defect. Inhibitors of N-ethylmaleimide sensitive factor (NSF), N-ethylmaleimide (NEM) or interfering peptides, prevent de-priming in munc18-1/2SWAP or munc13-1 null synapses, but not in CAPS-1/2 null, another priming-deficient mutant. NEM rescues synaptic transmission in munc13-1 null and munc18-1/2SWAP synapses, in acute munc13-1 null slices and even partially in munc13-1/2 double null synapses. Together these data indicate that Munc13-1 and Munc18-1, but not CAPS-1/2, stabilize primed synaptic vesicles by preventing NSF-dependent de-priming.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Female
  • Mice
  • Mice, Inbred C57BL
  • Munc18 Proteins / genetics
  • Munc18 Proteins / metabolism*
  • N-Ethylmaleimide-Sensitive Proteins / genetics
  • N-Ethylmaleimide-Sensitive Proteins / metabolism*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • SNARE Proteins / genetics
  • SNARE Proteins / metabolism
  • Synapses / metabolism
  • Synaptic Transmission
  • Synaptic Vesicles / genetics
  • Synaptic Vesicles / metabolism*

Substances

  • CAPS2 protein, mouse
  • Cadps protein, mouse
  • Calcium-Binding Proteins
  • Munc18 Proteins
  • Nerve Tissue Proteins
  • SNARE Proteins
  • Stxbp1 protein, mouse
  • Unc13a protein, mouse
  • N-Ethylmaleimide-Sensitive Proteins
  • Nsf protein, mouse