No role for Ca++ or protein kinase C in alpha-1A adrenergic receptor activation of mitogen-activated protein kinase pathways in transfected PC12 cells
No role for Ca++ or protein kinase C in alpha-1A adrenergic receptor activation of mitogen-activated protein kinase pathways in transfected PC12 cells
复制标题
DOI：
10.1124/mol.55.2.296
复制
发表时间：
1999-02-01
影响因子：
3.6
通讯作者：
Minneman, KP
中科院分区：
文献类型：
--
作者：
Berts, A;Zhong, HY;Minneman, KP
我们研究了Ca++和蛋白激酶C（PKC）在α-1A肾上腺素能受体（AR）介导的有丝分裂原活化蛋白激酶通路的激活中的作用。在稳定转染人α-1A AR的PC 12细胞中，去甲肾上腺素（NE）强烈激活细胞外信号调节激酶（ERK）和c-jun-NH 2-末端激酶（JNK）。10纳摩尔毒胡萝卜素（TG）增加细胞质Ca++至少尽可能多的NE，但不激活ERK或JNK。较高浓度的TG引起ERK的小激活，但不是JNK。通过TG预处理清空[Ca++]（i）库可阻止NE刺激的[Ca++]（i）增加，但不能阻止ERK或JNK激活。Ca ~（++）螯合剂双（2-氨基苯氧基）乙烷-N-N '-N'-四乙酸酯（BAPTA）剂量依赖性地阻断NE刺激的Ca ~（++）反应，但不阻断ERK或JNK激活。NE增加Pyk 2的酪氨酸磷酸化，这种反应既不被BAPTA阻断，也不被TG模仿。佛波酯肿瘤促进剂（TPA）引起ERK的剂量依赖性激活，10 nM TG增强。TPA引起的JNK相对于NE引起的只有小的激活，而不受TG的影响。PKC抑制剂bisindolylmaleimide I剂量依赖性地抑制TPA对ERK和JNK的激活，但不抑制NE。ATP和UTP通过内源性P_2Y_2受体激活类似的促分裂原活化蛋白激酶反应，并且这些反应不被BAPTA或双吲哚马来酰亚胺I阻断，表明这些结果可推广到其他G（q/11）偶联受体。结果表明，Ca ~（++）释放和PKC激活对于α-1A AR介导的PC_（12）细胞促分裂反应的激活既不是必需的，也不是充分的。
We studied the role of Ca++ and protein kinase C (PKC) in alpha-1A adrenergic receptor (AR)-mediated activation of mitogen-activated protein kinase pathways in PC12 cells. In PC12 cells stably transfected with the human alpha-1A AR, norepinephrine (NE) strongly activated both extracellular signal regulated kinases (ERKs) and c-jun-NH2-terminal kinases (JNK). Ten nanomolar thapsigargin (TG) increased cytoplasmic Ca++ at least as much as NE but did not activate ERKs or JNK. Higher concentrations of TG caused a small activation of ERKs but not JNK. Emptying [Ca++](i) stores by pretreatment with TG prevented the NE-stimulated increase in [Ca++](i) but not ERK or JNK activation. The Ca++ chelator bis(2-aminophenoxy)ethane-N-N-N'-N'-tetraacetate (BAPTA) dose dependently abolished NE-stimulated Ca++ responses but not ERK or JNK activation. NE increased tyrosine phosphorylation of Pyk2, and this response was neither blocked by BAPTA nor mimicked by TG. The phorbol ester tumor promoting agent (TPA) caused a dose-dependent activation of ERKs that was potentiated by 10 nM TG. TPA caused only a small activation of JNK relative to that caused by NE, which was not affected by TG. The potent PKC inhibitor bisindolylmaleimide I dose dependently inhibited ERK and JNK activation by TPA, but not NE. ATP and UTP activated similar mitogen-activated protein kinase responses through endogenous P2Y2 receptors, and these responses were not blocked by BAPTA or bisindolylmaleimide I, suggesting that these results may be generalizable to other G(q/11)-coupled receptors, The results suggest that Ca++ release and PKC activation are neither necessary nor sufficient for alpha-1A AR-mediated activation of mitogenic responses in PC12 cells.