Glucagon-like peptide 1 induces pancreatic beta-cell proliferation via transactivation of the epidermal growth factor receptor.
Glucagon-like peptide 1 induces pancreatic beta-cell proliferation via transactivation of the epidermal growth factor receptor.
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发表时间：
2003
期刊：
影响因子：
7.7
通讯作者：
J. Buteau;S. Foisy;E. Joly;M. Prentki
中科院分区：
文献类型：
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作者：
J. Buteau;S. Foisy;E. Joly;M. Prentki
我们以前提供的证据表明，胰高血糖素样肽1（GLP-1）诱导胰腺β细胞生长与葡萄糖的磷脂酰肌醇（PI）3-激酶和蛋白激酶C ζ依赖性的方式非相加。然而，G蛋白偶联受体（GPCR）超家族成员GLP-1受体（GLP-1 R）激活PI 3-激酶信号通路以促进β细胞生长的确切机制仍不清楚。我们假设GLP-1 R可通过表皮生长因子（EGF）受体（EGFR）的反式激活激活PI 3-激酶并促进β细胞增殖，这一事件可能通过激活c-Src和产生推定的内源性EGF样配体与GPCR相关。c-Src抑制剂PP 1和EGFR特异性抑制剂AG 1478均阻断INS（832/13）细胞以及分离的大鼠胰岛中GLP-1诱导的[（3）H]胸苷掺入，而只有AG 1478抑制EGFR激动剂β细胞素（BTC）的增殖作用。两种化合物也抑制GLP-1诱导的PI 3-激酶活化。在INS（832/13）细胞中观察到EGFR酪氨酸磷酸化响应GLP-1的时间依赖性增加。EGFR的这种反式激活对药物PP 1和AG 1478都敏感。发现GLP-1和BTC对INS细胞增殖的作用不是相加的。INS细胞中显性阴性EGFR与逆转录病毒表达载体的过表达减少了GLP-1诱导的β细胞增殖。INS细胞的GLP-1处理引起细胞表面相关BTC的减少，如FACS分析所示。此外，金属蛋白酶抑制剂GM 6001和抗BTC中和抗体抑制GLP-1增殖作用。最后，将缺乏GLP-1应答性的前列腺癌细胞系LNCaP与INS细胞共培养，在GLP-1存在下增加了LNCaP细胞增殖，从而揭示了INS细胞应答GLP-1分泌生长因子。在共培养实验中，在GLP-1存在下，GM 6001和抗BTC中和抗体抑制LNCaP细胞增殖增加。结果与GLP-1通过EGFR的反式激活增加PI 3-激酶活性并增强β细胞增殖的模型一致，EGFR的反式激活需要膜锚定BTC或其他EGF样配体的蛋白水解加工。
We previously provided evidence that glucagon-like peptide 1 (GLP-1) induces pancreatic beta-cell growth nonadditively with glucose in a phosphatidylinositol (PI) 3-kinase- and protein kinase C zeta-dependent manner. However, the exact mechanism by which the GLP-1 receptor (GLP-1R), a member of the G protein-coupled receptor (GPCR) superfamily, activates the PI 3-kinase signaling pathway to promote beta-cell growth remains unknown. We hypothesized that the GLP-1R could activate PI 3-kinase and promote beta-cell proliferation through transactivation of the epidermal growth factor (EGF) receptor (EGFR), an event possibly linked to GPCRs via activation of c-Src and the production of putative endogenous EGF-like ligands. Both the c-Src inhibitor PP1 and the EGFR-specific inhibitor AG1478 blocked GLP-1-induced [(3)H]thymidine incorporation in INS(832/13) cells as well as in isolated rat islets, while only AG1478 inhibited the proliferative action of betacellulin (BTC), an EGFR agonist. Both compounds also suppressed GLP-1-induced PI 3-kinase activation. A time-dependent increase in tyrosine phosphorylation of the EGFR in response to GLP-1 was observed in INS(832/13) cells. This transactivation of the EGFR was sensitive to both the pharmacological agents PP1 and AG1478. The action of GLP-1 and BTC on INS cell proliferation was found to be not additive. Overexpression of a dominant-negative EGFR in INS cells with a retroviral expression vector curtailed GLP-1-induced beta-cell proliferation. GLP-1 treatment of INS cells caused a decrease in cell surface-associated BTC, as shown by FACS analysis. Also, the metalloproteinase inhibitor GM6001 and an anti-BTC neutralizing antibody suppressed the GLP-1 proliferative effect. Finally, coculturing the prostatic cancer cell line LNCaP that lacks GLP-1 responsiveness with INS cells increased LNCaP cell proliferation in the presence of GLP-1, thus revealing that INS cells secrete a growth factor in response to GLP-1. GM6001 and an anti-BTC neutralizing antibody suppressed increased LNCaP cell proliferation in the presence of GLP-1 in the coculture experiments. The results are consistent with a model in which GLP-1 increases PI 3-kinase activity and enhances beta-cell proliferation via transactivation of the EGFR that would require the proteolytic processing of membrane-anchored BTC or other EGF-like ligands.