Phorbolester-activated Munc13-1 and ubMunc13-2 exert opposing effects on dense-core vesicle secretion
- University of Copenhagen, Denmark
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Germany
Abstract
Munc13 proteins are priming factors for SNARE-dependent exocytosis, which are activated by diacylglycerol (DAG)-binding to their C1-domain. Several Munc13 paralogs exist, but their differential roles are not well understood. We studied the interdependence of phorbolesters (DAG mimics) with Munc13-1 and ubMunc13-2 in mouse adrenal chromaffin cells. Although expression of either Munc13-1 or ubMunc13-2 stimulated secretion, phorbolester was only stimulatory for secretion when ubMunc13-2 expression dominated, but inhibitory when Munc13-1 dominated. Accordingly, phorbolester stimulated secretion in wildtype cells, or cells overexpressing ubMunc13-2, but inhibited secretion in Munc13-2/Unc13b knockout (KO) cells or in cells overexpressing Munc13-1. Phorbolester was more stimulatory in the Munc13-1/Unc13a KO than in WT littermates, showing that endogenous Munc13-1 limits the effects of phorbolester. Imaging showed that ubMunc13-2 traffics to the plasma membrane with a time-course matching Ca2+-dependent secretion, and trafficking is independent of Synaptotagmin-7 (Syt7). However, in the absence of Syt7, phorbolester became inhibitory for both Munc13-1 and ubMunc13-2 driven secretion, indicating that stimulatory phorbolester x Munc13-2 interaction depends on functional pairing with Syt7. Overall, DAG/phorbolester, ubMunc13-2 and Syt7 form a stimulatory triad for dense-core vesicle priming.
Data availability
All data generates or analysed during this study are included in the manuscript and supporting files; the Source Data file contain the numerical data used to generate the figures.
Article and author information
Author details
Jakob Balslev Sørensen
Funding
Novo Nordisk Fonden (NNF19OC0058298)
- Jakob Balslev Sørensen
Independent Research Fund Denmark (0134-00141A)
- Jakob Balslev Sørensen
Lundbeckfonden (R277-2018-802)
- Jakob Balslev Sørensen
Deutsche Forschungsgemeinschaft (EXC-2049 - 390688087)
- Noa Lipstein
Deutsche Forschungsgemeinschaft (SFB1286/A11)
- Noa Lipstein
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Houy et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Phorbolester-activated Munc13-1 and ubMunc13-2 exert opposing effects on dense-core vesicle secretion
eLife 11:e79433.
https://doi.org/10.7554/eLife.79433
