Adenylyl cyclase 8 is central to glucagon-like peptide 1 signalling and effects of chronically elevated glucose in rat and human pancreatic beta cells
Adenylyl cyclase 8 is central to glucagon-like peptide 1 signalling and effects of chronically elevated glucose in rat and human pancreatic beta cells
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DOI：
10.1007/s00125-010-1955-x
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发表时间：
2011-02-01
期刊：
影响因子：
8.2
通讯作者：
Lang, J.
中科院分区：
文献类型：
--
作者：
Roger, B.;Papin, J.;Lang, J.
葡萄糖和肠促胰岛素通过钙和cAMP调节β细胞功能、基因表达和胰岛素胞吐。长期暴露于葡萄糖升高（也称为糖毒性）会扰乱钙稳态，但对cAMP信号传导知之甚少。因此，我们研究了葡萄糖对这一途径的长期影响，特别是关于胰高血糖素样肽1 （GLP-1）。我们将INS-1E细胞和大鼠或人胰岛暴露在不同水平的葡萄糖中3天，并通过测量膜电容来测定第二信使（cAMP, Ca2+），转录谱，cAMP响应元件（CRE）的激活和分泌方面的功能反应。此外，我们还直接调节了钙敏感腺苷酸环化酶（ADCY8）和GLP-1受体（GLP1R）的丰度。在葡萄糖升高（> 5.5 mmol/l）培养的INS-1E细胞中，GLP-1或福斯克林介导的胞质钙、camp水平或胰岛素分泌的增加大大减少。转录谱的统计分析确定cAMP途径是葡萄糖调节的主要靶点。定量PCR证实了这些发现，并揭示了在大鼠和人类胰岛中钙敏感腺苷酸环化酶ADCY8的显著下调。重新表达ADCY8，而不是GLP1R，恢复了INS-1E细胞和大鼠胰岛中葡萄糖毒性的GLP-1信号。此外，这种腺苷酸环化酶的敲除表明，glp -1诱导cAMP生成、钙信号传导、下游靶细胞CRE的激活以及cAMP升高剂（通过电容测量评估）的胞吐直接通过ADCY8进行。camp介导的途径由葡萄糖模拟，钙敏感的ADCY8的下调在这里起着核心作用，包括通过GLP1R的信号传导。
Glucose and incretins regulate beta cell function, gene expression and insulin exocytosis via calcium and cAMP. Prolonged exposure to elevated glucose (also termed glucotoxicity) disturbs calcium homeostasis, but little is known about cAMP signalling. We therefore investigated long-term effects of glucose on this pathway with special regard to the incretin glucagon-like peptide 1 (GLP-1).We exposed INS-1E cells and rat or human islets to different levels of glucose for 3 days and determined functional responses in terms of second messengers (cAMP, Ca2+), transcription profiles, activation of cAMP-responsive element (CRE) and secretion by measuring membrane capacitance. Moreover, we modulated directly the abundance of a calcium-sensitive adenylyl cyclase (ADCY8) and GLP-1 receptor (GLP1R).GLP-1- or forskolin-mediated increases in cytosolic calcium, cAMP-levels or insulin secretion were largely reduced in INS-1E cells cultured at elevated glucose (> 5.5 mmol/l). Statistical analysis of transcription profiles identified cAMP pathways as major targets regulated by glucose. Quantitative PCR confirmed these findings and unravelled marked downregulation of the calcium-sensitive adenylyl cyclase ADCY8 also in rat and in human islets. Re-expression of ADCY8, but not of the GLP1R, recovered GLP-1 signalling in glucotoxicity in INS-1E cells and in rat islets. Moreover, knockdown of this adenylyl cyclase showed that GLP-1-induced cAMP generation, calcium signalling, activation of the downstream target CRE and direct amplification of exocytosis by cAMP-raising agents (evaluated by capacitance measurement) proceeds via ADCY8.cAMP-mediated pathways are modelled by glucose, and downregulation of the calcium-sensitive ADCY8 plays a central role herein, including signalling via the GLP1R.