title: The trans-SNARE-regulating function of Munc18-1 is essential to synaptic exocytosis.
abstract: The fusion of neurotransmitter-filled synaptic vesicles with the plasma membrane requires two classes of molecules-SNAP receptor (SNARE) and Sec1/Munc18 (SM) protein. Reconstitution studies suggest that the SM protein Munc18-1 promotes the zippering of trans-SNARE complexes and accelerates the kinetics of SNARE-dependent membrane fusion. However, the physiological role of this trans-SNARE-regulating function in synaptic exocytosis remains to be established. Here we first demonstrate that two mutations in the vesicle-anchored v-SNARE selectively impair the ability of Munc18-1 to promote trans-SNARE zippering, whereas other known Munc18-1/SNARE-binding modes are unaffected. In cultured neurons, these v-SNARE mutations strongly inhibit spontaneous as well as evoked neurotransmitter release, providing genetic evidence for the trans-SNARE-regulating function of Munc18-1 in synaptic exocytosis. Finally, we show that the trans-SNARE-regulating function of Munc18-1 is compromised by a mutation associated with Ohtahara Syndrome, a severe form of epilepsy.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Chong
authors.initials: C
authors.lastname: Shen
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Shailendra S
authors.initials: SS
authors.lastname: Rathore
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Haijia
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Gulbranson
authors.affiliation: State Key Laboratory of Membrane Biology, School of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Hua
authors.affiliation: State Key Laboratory of Membrane Biology, School of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA.
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Schoppa
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Jingshi
authors.initials: J
authors.lastname: Shen
mesh_terms: D000818:Animals; D001665:Binding Sites; D002540:Cerebral Cortex / Q000166:cytology; D004827:Epilepsy / Q000235:genetics; D005089:Exocytosis / Q000235:genetics*; D015151:Immunoblotting; D008081:Liposomes / Q000378:metabolism; D008561:Membrane Fusion; D051379:Mice; D051938:Munc18 Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D009435:Synaptic Transmission / Q000235:genetics*; D050988:Vesicle-Associated Membrane Protein 2 / Q000235:genetics*
chemical_list: D008081:Liposomes; D051938:Munc18 Proteins; D050600:SNARE Proteins; C497938:Stxbp1 protein, mouse; D050988:Vesicle-Associated Membrane Protein 2; C494808:vesicle-associated membrane protein 2, mouse