The calcitonin receptor stimulates Shc tyrosine phosphorylation and Erk1/2 activation -: Involvement of Gi, protein kinase C, and calcium
The calcitonin receptor stimulates Shc tyrosine phosphorylation and Erk1/2 activation -: Involvement of Gi, protein kinase C, and calcium
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DOI：
10.1074/jbc.273.31.19809
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发表时间：
1998-07-31
影响因子：
4.8
通讯作者：
Baron, R
中科院分区：
文献类型：
--
作者：
Chen, Y;Shyu, JF;Baron, R
虽然已经确定腺苷酸环化酶和磷脂酶C-β是降钙素受体的两种近端信号效应物，但更远端的信号传导途径还没有得到很好的表征。G蛋白偶联受体可通过G（s）-、G（i）-或G（q）-依赖性信号通路激活Erk 1/2，这取决于所检测的特定受体和细胞类型。由于降钙素受体可以与所有这三种G蛋白偶联，因此研究了降钙素激活Erk 1/2的能力。在稳定表达兔降钙素受体Cia亚型的HEK 293细胞系中，降钙素诱导Shc酪氨酸磷酸化、Shc-Grb 2结合和Erk 1/2磷酸化和活化的时间和浓度依赖性增加。灭活G（i）的百日咳毒素和蛋白激酶C抑制剂calphostin C均部分抑制降钙素诱导的Shc酪氨酸磷酸化、Shc-Grb 2结合和Erk 1/2磷酸化。相反，毛喉素和蛋白激酶A抑制剂H89对基础或降钙素刺激的Erk 1/2磷酸化均无显著影响。我们的研究结果表明，降钙素受体诱导HEK 293细胞中的Shc磷酸化和Erk 1/2激活的平行G（i）和PRO依赖的机制。降钙素诱导的胞浆游离Ca 2+的升高是Erk 1/2磷酸化所必需的，因为通过螯合胞浆和细胞外Ca 2+来防止胞浆游离Ca 2+的任何变化消除了响应。然而，降钙素诱导的Ca 2+变化不足以解释降钙素诱导的Erk 1/2磷酸化，因为用100 nM离子霉素或10 μ M毒胡萝卜素处理诱导的Ca 2+升高与降钙素诱导的Ca 2+升高相当，诱导的Erk 1/2磷酸化显著低于降钙素诱导的Erk 1/2磷酸化。Erk 1/2可能作为下游效应子介导细胞对降钙素刺激的反应具有重要作用。
While it is web established that adenylyl cyclase and phospholipase C-beta are two proximal signal effecters for the calcitonin receptor, the more distal signaling pathways are less well characterized. G protein-coupled receptors can activate Erk1/2 by G(s)-, G(i)-, or G(q)-dependent signaling pathways, depending on the specific receptor and cell type examined. Since the calcitonin receptor can couple to all three of these G proteins, the ability of calcitonin to activate Erk1/2 was investigated. Calcitonin induced time- and concentration-dependent increases in Shc tyrosine phosphorylation, Shc-Grb2 association and Erk1/2 phosphorylation and activation in a HEK 293 cell line that stably expresses the rabbit calcitonin receptor Cia isoform. Pertussis toxin, which inactivates G(i), and calphostin C, a protein kinase C inhibitor, each partially inhibited calcitonin-induced Shc tyrosine phosphorylation, Shc-Grb2 association, and Erk1/2 phosphorylation. In contrast, neither forskolin nor H89, a protein kinase A inhibitor, had a significant effect on basal or calcitonin-stimulated Erk1/2 phosphorylation. Our results suggest that the calcitonin receptor induces Shc phosphorylation and Erk1/2 activation in HEK293 cells by parallel G(i)- and PRO-dependent mechanisms. The calcitonin-induced elevation of cytosolic free Ca2+ was required for Erk1/2 phosphorylation, since preventing any change in cytosolic free Ca2+ by chelating both cytosolic and extracellular Ca2+ abolished the response. However, the change in Ca2+ that is induced by calcitonin is not sufficient to account for the calcitonin-induced Erk1/2 phosphorylation, since treatment with 100 nM ionomycin or 10 mu M thapsigargin, each of which induced elevations of Ca2+ comparable to those induced by calcitonin, induced significantly less Erk1/2 phosphorylation than that induced by calcitonin. Erk1/2 may have important roles as downstream effecters mediating cellular responses to calcitonin stimulation.