Role of G protein-coupled receptor kinases in glucose-dependent insulinotropic polypeptide receptor signaling.
Role of G protein-coupled receptor kinases in glucose-dependent insulinotropic polypeptide receptor signaling.
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DOI：
10.1210/endo.141.3.7365
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发表时间：
2000-03
期刊：
影响因子：
4.8
通讯作者：
C. Tseng;Xiao-Ying Zhang
中科院分区：
文献类型：
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作者：
C. Tseng;Xiao-Ying Zhang
葡萄糖依赖性促胰岛素多肽受体（GIPR）是II类G蛋白偶联受体的成员。最近的研究表明，脱敏的GIPR可能有助于在II型糖尿病患者的胰岛素分泌受损，但GIPR信号终止的分子机制是未知的。利用稳定转染GIPR互补DNA的HEK L293细胞（L293-GIPR），研究GIPR的脱敏机制。GIP剂量依赖性地增加细胞内cAMP水平在L293-GIPR细胞，但这种反应被废除（65%）与G蛋白偶联受体激酶2（GRK 2），但不与GRK 5或GRK 6共转染。β-arrestin-1转染也诱导了GIP刺激的cAMP产生的显著减少，并且GRK 2和β-arrestin-1共转染的这种效果比单独转染的效果更大。在β TC 3细胞中，GRK 2或β-arrestin-1的表达减弱了GIP诱导的胰岛素释放和cAMP产生，而葡萄糖刺激的胰岛素分泌不受影响。通过北方印迹分析鉴定GRK 2和β-抑制蛋白-1信使RNA在β TC 3和L293细胞中内源性表达。GRK 2的过表达增强激动剂诱导的GIPR磷酸化，但受体内吞作用不受GRKs或β-arrestin-1共转染的影响。这些结果提示GRK 2/beta-arrestin-1系统在调节GIP介导的胰岛细胞胰岛素分泌中的潜在作用。此外，GRK介导的受体磷酸化对于GIPR的内吞作用不是必需的。
The glucose-dependent insulinotropic polypeptide receptor (GIPR) is a member of class II G protein-coupled receptors. Recent studies have suggested that desensitization of the GIPR might contribute to impaired insulin secretion in type II diabetic patients, but the molecular mechanisms of GIPR signal termination are unknown. Using HEK L293 cells stably transfected with GIPR complementary DNA (L293-GIPR), the mechanisms of GIPR desensitization were investigated. GIP dose dependently increased intracellular cAMP levels in L293-GIPR cells, but this response was abolished (65%) by cotransfection with G protein-coupled receptor kinase 2 (GRK2), but not with GRK5 or GRK6. Beta-arrestin-1 transfection also induced a significantly decrease in GIP-stimulated cAMP production, and this effect was greater with cotransfection of both GRK2 and beta-arrestin-1 than with either alone. In betaTC3 cells, expression of GRK2 or beta-arrestin-1 attenuated GIP-induced insulin release and cAMP production, whereas glucose-stimulated insulin secretion was not affected. GRK2 and beta-arrestin-1 messenger RNAs were identified by Northern blot analysis to be expressed endogenously in betaTC3 and L293 cells. Overexpression of GRK2 enhanced agonist-induced GIPR phosphorylation, but receptor endocytosis was not affected by cotransfection with GRKs or beta-arrestin-1. These results suggest a potential role for GRK2/beta-arrestin-1 system in modulating GIP-mediated insulin secretion in pancreatic islet cells. Furthermore, GRK-mediated receptor phosphorylation is not required for endocytosis of the GIPR.