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Molecular mechanisms of insulin signal transduction and diabetes mellitus

胰岛素信号转导与糖尿病的分子机制

基本信息

批准号：
18390104
负责人：
EBINA Yousuke
金额：
$ 10.77万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18390104/
关键词：
insulin receptor soluble ectodomain diabetes signal transduction GLUT4 translocation AS160 Gq coupled receptor インスリン

项目摘要

The ectodomains of receptors for several cytokines and growth factors have been found to circulate in plasma. Thus, the existence of soluble IR in human serum has been suspected.Furthermore, transgenic mice secreting soluble IRα into the plasma showed chronic hyperglycemia. Here, we established novel enzyme-linked immunosorbent assay (ELISA) systems to measure both the ectodomain (α-subunit and a part of β-subunit) of IR and full length of IR.With these ELISA systems, we report that soluble hlRα with parts of extracellular region of hIRβ, but not as a whole IR or with intact hlRβ, is present in human plasma and that its plasma level is elevated in patients with elevated blood glucose. The ectodomain of IR may be cleaved, at least in part, by hyperglycemic state-associated mechanisms.We and others previously reported that the activation of Gaq protein- coupled receptors (GaqPCRs) also stimulates GLUT4 translocation and glucose uptake in several cell lines. Here, we report that the activation of GaqPCRs also promoted the phosphorylation of AS160, Akt substrate of 160 KDa which is Rab GTPase activating protein (GAP), by 5'-AMP activated protein kinase (AMPK). The suppression of AS160 phosphorylation by AMPKα1 subunit knockdown using siRNA promoted GLUT4 vesicle retention at intracellular compartments, but did not affect a fold increase of the Gaq- stimulated GLUT4 translocation. These results suggest that AS160 is a common mediator of the GLUT4 vesicle trafficking stimulated by insulin and by the activation of GaqPCR. The AS160 regulates the intracellular distribution of the GLUT4 vesicles and its retention inside the cells.

已发现几种细胞因子和生长因子受体的胞外域在血浆中循环。因此，人们怀疑人血清中存在可溶性IR。此外，将可溶性IRα分泌到血浆中的转基因小鼠表现出慢性高血糖。在这里，我们建立了新型酶联免疫吸附测定（ELISA）系统来测量 IR 的胞外域（α 亚基和 β 亚基的一部分）和 IR 全长。通过这些 ELISA 系统，我们报告了人血浆中存在可溶性 hlRα 和部分 hIRβ 胞外区，但不是整个 IR 或完整的 hlRβ，并且其血糖升高的患者血浆水平升高。 IR 的胞外域可能至少部分地被高血糖状态相关机制裂解。我们和其他人之前报道过 Gaq 蛋白偶联受体 (GaqPCR) 的激活也会刺激几种细胞系中的 GLUT4 易位和葡萄糖摄取。在此，我们报道 GaqPCR 的激活还促进 5'-AMP 激活蛋白激酶 (AMPK) 磷酸化 AS160（160 KDa 的 Akt 底物，即 Rab GTPase 激活蛋白 (GAP)）。使用 siRNA 通过 AMPKα1 亚基敲低来抑制 AS160 磷酸化，促进 GLUT4 囊泡保留在细胞内区室，但不影响 Gaq 刺激的 GLUT4 易位的倍数增加。这些结果表明 AS160 是胰岛素和 GaqPCR 激活刺激的 GLUT4 囊泡运输的常见介导者。 AS160 调节 GLUT4 囊泡的细胞内分布及其在细胞内的保留。