Diacylglycerol Enhances Synaptic Vesicle Priming and Release
Publication Title: Roles for diacylglycerol in synaptic vesicle priming and release revealed by complete reconstitution of core protein machinery
Summary
- Question
- This study examined the molecular mechanisms underlying synaptic vesicle priming and release, focusing on the roles of diacylglycerol (DAG), Munc13, and Munc18 in facilitating neurotransmitter release. The researchers aimed to understand how these proteins interact to prepare synaptic vesicles for rapid calcium-triggered fusion.
- Why it Matters
- Neurotransmitter release is essential for communication between nerve cells, which underpins brain function and behavior. Understanding how synaptic vesicles are primed and released can provide insights into neurological processes and diseases, such as Alzheimer's and epilepsy, that involve disruptions in neurotransmitter signaling. This research could also inform the development of therapies targeting synaptic dysfunction.
- Methods
- The researchers used a biochemically defined in vitro system that reconstituted the core protein machinery involved in synaptic vesicle release. This included key proteins such as SNAREs (proteins essential for membrane fusion), Munc13, Munc18, Synaptotagmin, and Complexin. They tracked vesicle docking, priming, and calcium-triggered fusion using fluorescence microscopy and single-vesicle imaging techniques.
- Key Findings
- The study found that Munc18 acts as a nucleator for the SNARE complex, while Munc13 accelerates SNARE assembly in a DAG-dependent manner. Low concentrations of DAG improved vesicle priming and calcium-triggered release, while high concentrations reduced the regulatory 'clamping' mechanism, leading to spontaneous vesicle fusion. DAG binding to Munc13 significantly enhanced the formation of stably docked, release-ready vesicles and facilitated rapid fusion within milliseconds upon calcium influx.
- Implications
- These findings highlight the critical roles of Munc13, Munc18, and DAG in ensuring efficient neurotransmitter release. By elucidating how these proteins cooperate to prime synaptic vesicles, the research advances our understanding of synaptic function and its regulation. The results may have implications for treating neurological disorders characterized by impaired synaptic activity, offering potential targets for drug development.
- Next Steps
- The researchers suggest further studies to explore the structural transitions of Munc13 during vesicle priming and the molecular choreography of SNARE assembly. Additional research is needed to determine how DAG interacts with other regulatory elements in the synaptic vesicle fusion process.
- Funding Information
- This research was supported by the National Institutes of Health (NIH) under grants DK027044 and GM141194. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Yale University also provided funding and support for this research.
Full Citation
Sundaram R, Chatterjee A, Bera M, Grushin K, Panda A, Li F, Coleman J, Lee S, Ramakrishnan S, Ernst A, Gupta K, Rothman J, Krishnakumar S. Roles for diacylglycerol in synaptic vesicle priming and release revealed by complete reconstitution of core protein machinery. Proceedings Of The National Academy Of Sciences Of The United States Of America 2023, 120: e2309516120. PMID: 37590407, PMCID: PMC10450444, DOI: 10.1073/pnas.2309516120.
This AI-assisted summary has been reviewed and approved by at least one of the study's authors to ensure it accurately reflects the research.
Authors
Venkat Kalyana Sundaram, PhD
First AuthorResearch Scientist in Cell Biology
Shyam Krishnakumar, PhD
Last AuthorAssistant Professor
Additional Yale School of Medicine Authors
Other Authors
Research Themes
Keywords
Concepts
- core protein machinery;
- release-ready vesicles;
- synaptic vesicle priming;
- vesicle priming;
- protein machinery;
- single-molecule imaging;
- SNAREpin assembly;
- functional intermediates;
- functional reconstitution;
- Munc13;
- diacylglycerol;
- coordinated action;
- Munc18;
- vesicles;
- machinery;
- complete reconstitution;
- new role;
- selective effect;
- detailed characterization;
- chaperones;
- rate of ca;
- reconstitution;
- VAMP2;
- complexin;
- mutations