Abstract
Tyrosine kinases are important regulators of synaptic strength. Here, we describe a key component of the synaptic vesicle release machinery, Munc18-1, as a phosphorylation target for neuronal Src family kinases (SFKs). Phosphomimetic Y473D mutation of a SFK phosphorylation site previously identified by brain phospho-proteomics abolished the stimulatory effect of Munc18-1 on SNARE complex formation ("SNARE-templating") and membrane fusion in vitro. Furthermore, priming but not docking of synaptic vesicles was disrupted in hippocampal munc18-1-null neurons expressing Munc18-1Y473D. Synaptic transmission was temporarily restored by high-frequency stimulation, as well as by a Munc18-1 mutation that results in helix 12 extension, a critical conformational step in vesicle priming. On the other hand, expression of non-phosphorylatable Munc18-1 supported normal synaptic transmission. We propose that SFK-dependent Munc18-1 phosphorylation may constitute a potent, previously unknown mechanism to shut down synaptic transmission, via direct occlusion of a Synaptobrevin/VAMP2 binding groove and subsequent hindrance of conformational changes in domain 3a responsible for vesicle priming. This would strongly interfere with the essential post-docking SNARE-templating role of Munc18-1, resulting in a largely abolished pool of releasable synaptic vesicles.
Original language | English |
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Pages (from-to) | 300-320 |
Number of pages | 21 |
Journal | EMBO Journal |
Volume | 37 |
Issue number | 2 |
Early online date | 17 Nov 2017 |
DOIs | |
Publication status | Published - 17 Jan 2018 |
Keywords
- Munc18-1
- Priming
- SNARE
- Src
- Synaptic transmission