Glucagon receptor activates extracellular signal-regulated protein kinase 1/2 via cAMP-dependent protein kinase
Glucagon receptor activates extracellular signal-regulated protein kinase 1/2 via cAMP-dependent protein kinase
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DOI：
10.1073/pnas.131200398
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发表时间：
2001-08-28
影响因子：
11.1
通讯作者：
Sakmar, TP
中科院分区：
文献类型：
--
作者：
Jiang, YW;Cypess, AM;Sakmar, TP
我们制备了一种表达胰高血糖素受体的稳定细胞系，以表征G（s）偶联受体刺激对细胞外信号调节蛋白激酶1/2（ERK 1/2）活性的影响。胰高血糖素处理的细胞系引起cAMP浓度的剂量依赖性增加，cAMP依赖性蛋白激酶（PKA）的激活，和细胞内钙的瞬时释放。胰高血糖素处理还引起促分裂原活化蛋白激酶激酶/ERK激酶（MEK 1/2）和ERK 1/2的快速剂量依赖性磷酸化和活化。抑制PKA或MEK 1/2可阻断胰高血糖素对ERK 1/2的激活。然而，在胰高血糖素处理后，未观察到MEK的几种上游激活剂（包括Ras、Rap 1和Raf）的显著激活。此外，细胞内钙离子的螯合作用降低了胰高血糖素介导的ERK 1/2激活。在瞬时转染实验中，结合胰高血糖素但未能增加细胞内cAMP和钙浓度的胰高血糖素受体突变体显示没有胰高血糖素刺激的ERK 1/2磷酸化。我们的结论是胰高血糖素诱导的MEK 1/2和ERK 1/2激活是由PKA介导的，细胞内钙离子浓度的增加是最大的ERK激活所必需的。
We prepared a stable cell line expressing the glucagon receptor to characterize the effect of G(s)-coupled receptor stimulation on extracellular signal-regulated protein kinase 1/2 (ERK1/2) activity. Glucagon treatment of the cell line caused a dose-dependent increase in cAMP concentration, activation of cAMP-dependent protein kinase (PKA), and transient release of intracellular calcium. Glucagon treatment also caused rapid dose-dependent phosphorylation and activation of mitogen-activated protein kinase kinase/ERK kinase (MEK1/2) and ERK1/2. Inhibition of either PKA or MEK1/2 blocked ERK1/2 activation by glucagon. However, no significant activation of several upstream activators of MEK, including Ras, Rap1, and Raf, was observed in response to glucagon treatment. In addition, chelation of intracellular calcium reduced glucagon-mediated ERK1/2 activation. In transient transfection experiments, glucagon receptor mutants that bound glucagon but failed to increase intracellular cAMP and calcium concentrations showed no glucagon-stimulated ERK1/2 phosphorylation. We conclude that glucagon-induced MEK1/2 and ERK1/2 activation is mediated by PKA and that an increase in intracellular calcium concentration is required for maximal ERK activation.