Resident CAPS on dense-core vesicles docks and primes vesicles for fusion
Name
Kabachinski-2016-Resident CAPS on den.pdf
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Author(s)
Kielar-Grevstad, D. Michelle
Zhang, Xingmin
James, Declan J.
Martin, Thomas F. J.
Kabachinski, Gregory L.
Date Issued
December 2015
Journal
Molecular Biology of the Cell
Publisher
American Society for Cell Biology
Citation
Kabachinski, G., D. M. Kielar-Grevstad, X. Zhang, D. J. James, and T. F. J. Martin. “Resident CAPS on Dense-Core Vesicles Docks and Primes Vesicles for Fusion.” Molecular Biology of the Cell 27, no. 4 (February 15, 2016): 654–68.
Version
Final published version
Abstract
The Ca[superscript 2+]-dependent exocytosis of dense-core vesicles in neuroendocrine cells requires a priming step during which SNARE protein complexes assemble. CAPS (aka CADPS) is one of several factors required for vesicle priming; however, the localization and dynamics of CAPS at sites of exocytosis in live neuroendocrine cells has not been determined. We imaged CAPS before, during, and after single-vesicle fusion events in PC12 cells by TIRF microscopy. In addition to being a resident on cytoplasmic dense-core vesicles, CAPS was present in clusters of approximately nine molecules near the plasma membrane that corresponded to docked/tethered vesicles. CAPS accompanied vesicles to the plasma membrane and was present at all vesicle exocytic events. The knockdown of CAPS by shRNA eliminated the VAMP-2–dependent docking and evoked exocytosis of fusion-competent vesicles. A CAPS(ΔC135) protein that does not localize to vesicles failed to rescue vesicle docking and evoked exocytosis in CAPS-depleted cells, showing that CAPS residence on vesicles is essential. Our results indicate that dense-core vesicles carry CAPS to sites of exocytosis, where CAPS promotes vesicle docking and fusion competence, probably by initiating SNARE complex assembly.
MIT Department
Massachusetts Institute of Technology. Department of Biology
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DOI of Published Version
https://doi.org/10.1091/mbc.E15-07-0509
