Sorcin Links Pancreatic β-Cell Lipotoxicity to ER Ca2+ Stores
Sorcin Links Pancreatic β-Cell Lipotoxicity to ER Ca2+ Stores
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DOI：
10.2337/db15-1334
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发表时间：
2016-04-01
期刊：
影响因子：
7.7
通讯作者：
Leclerc, Isabelle
中科院分区：
文献类型：
--
作者：
Marmugi, Alice;Parnis, Julia;Leclerc, Isabelle
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Preserving beta-cell function during the development of obesity and insulin resistance would limit the worldwide epidemic of type 2 diabetes. Endoplasmic reticulum (ER) calcium (Ca2+) depletion induced by saturated free fatty acids and cytokines causes beta-cell ER stress and apoptosis, but the molecular mechanisms behind these phenomena are still poorly understood. Here, we demonstrate that palmitate-induced sorcin downregulation and subsequent increases in glucose-6-phosphatase catalytic subunit-2 (G6PC2) levels contribute to lipotoxicity. Sorcin is a calcium sensor protein involved in maintaining ER Ca2+ by inhibiting ryanodine receptor activity and playing a role in terminating Ca2+-induced Ca2+ release. G6PC2, a genome-wide association study gene associated with fasting blood glucose, is a negative regulator of glucose-stimulated insulin secretion (GSIS). High-fat feeding in mice and chronic exposure of human islets to palmitate decreases endogenous sorcin expression while levels of G6PC2 mRNA increase. Sorcin-null mice are glucose intolerant, with markedly impaired GSIS and increased expression of G6pc2. Under high-fat diet, mice overexpressing sorcin in the beta-cell display improved glucose tolerance, fasting blood glucose, and GSIS, whereas G6PC2 levels are decreased and cytosolic and ER Ca2+ are increased in transgenic islets. Sorcin may thus provide a target for intervention in type 2 diabetes.