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Trajkovski, M.* ; Mziaut, H.* ; Schubert, S.* ; Kalaidzidis, Y.* ; Altkrüger, A.* ; Solimena, M.*

Regulation of insulin granule turnover in pancreatic beta-cells by cleaved ICA512.

J. Biol. Chem. 283, 33719-33729 (2008)
DOI PMC
Open Access Gold as soon as Publ. Version/Full Text is submitted to ZB.
Insulin maintains homeostasis of glucose by promoting its uptake into cells from the blood. Hyperglycemia triggers secretion of insulin from pancreatic beta-cells. This process is mediated by secretory granule exocytosis. However, how beta-cells keep granule stores relatively constant is still unknown. ICA512 is an intrinsic granule membrane protein, whose cytosolic domain binds beta2-syntrophin, an F-actin-associated protein, and is cleaved upon granule exocytosis. The resulting cleaved cytosolic fragment, ICA512-CCF, reaches the nucleus and up-regulates the transcription of granule genes, including insulin and ICA512. Here, we show that ICA512-CCF also dimerizes with intact ICA512 on granules, thereby displacing it from beta2-syntrophin. This leads to increased granule mobility and insulin release. Based on these findings, we propose a model whereby the generation of ICA512-CCF first amplifies insulin secretion. The ensuing reduction of granule stores would then increase the probability of newly generated ICA512-CCF to reach the nucleus and enhance granule biogenesis, thus allowing beta-cells to constantly adjust production of granules to their storage size and consumption. Pharmacological modulation of these feedback loops may alleviate deficient insulin release in diabetes.
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Publication type Article: Journal article
Document type Scientific Article
Language english
Publication Year 2008
HGF-reported in Year 0
ISSN (print) / ISBN 0021-9258
e-ISSN 1083-351X
Quellenangaben Volume: 283, Issue: 48, Pages: 33719-33729 Article Number: , Supplement: ,
Publisher American Society for Biochemistry and Molecular Biology
Reviewing status Peer reviewed
Institute(s) Institute of Pancreatic Islet Research (IPI)
PubMed ID 18824546
Erfassungsdatum 2008-12-31