Cytosolic free Ca2+ plays an important role in the molecular mechanisms leading to regulated insulin secretion by the pancreatic β cell. A number of Ca2+-binding proteins have been implicated in this process. Here, we define the role of the Ca2+-binding protein neuronal Ca2+ sensor-1 (NCS-1) in insulin secretion. In pancreatic β cells, NCS-1 increases exocytosis by promoting the priming of secretory granules for release and increasing the number of granules residing in the readily releasable pool. The effect of NCS-1 on exocytosis is mediated through an increase in phosphatidylinositol (PI) 4-kinase β activity and the generation of phosphoinositides, specifically PI 4-phosphate and PI 4,5-bisphosphate. In turn, PI 4,5-bisphosphate controls exocytosis through the Ca2+-dependent activator protein for secretion present in β cells. Our results provide evidence for an essential role of phosphoinositide synthesis in the regulation of glucose-induced insulin secretion by the pancreatic β cell. We also demonstrate that NCS-1 and its downstream target, PI 4-kinase β;, are critical players in this process by virtue of their capacity to regulate the release competence of the secretory granules.
|Original language||English (US)|
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Jul 19 2005|
- Ca-dependent activator protein for secretion
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