Endogenous RGS protein action modulates μ-opioid signaling through Gαo -: Effects on adenylyl cyclase, extracellular signal-regulated kinases, and intracellular calcium pathways
Endogenous RGS protein action modulates μ-opioid signaling through Gαo -: Effects on adenylyl cyclase, extracellular signal-regulated kinases, and intracellular calcium pathways
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DOI：
10.1074/jbc.m208885200
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发表时间：
2003-03-14
影响因子：
4.8
通讯作者：
Traynor, JR
中科院分区：
文献类型：
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作者：
Clark, MJ;Harrison, C;Traynor, JR
RGS （G蛋白信号传导调节因子）蛋白是异三聚体G蛋白的Galpha亚基的gtpase激活蛋白，通过快速循环G蛋白来调节信号传导。RGS蛋白可能通过物理或动力学支架机制整合受体和信号通路。为了确定这是否会导致激动剂信号的增强和/或选择性，我们制备了稳定表达mua -阿片受体和百日咳毒素不敏感或RGS-和百日咳毒素不敏感Galpha(o)的C6细胞。我们比较了表达rgs不敏感或rgs敏感的突变Galpha(o)的细胞之间G蛋白的激活、腺苷酸环化酶的抑制、细胞内钙释放的刺激以及ERK1/2 MAPK通路的激活。在表达rgs不敏感的Galpha的细胞中，mu受体激动剂[D-Ala(2), MePhe(4),Gly(5)-ol]脑啡肽和部分激动剂吗啡在抑制腺苷酸环化酶和激活MAPK方面更有效和/或具有更大的最大作用。相比之下，细胞内钙的阿片受体激动剂的增加受到的影响较小。这些结果与RGS蛋白的gtpase激活蛋白活性提供了一种控制，限制了激动剂通过效应途径的作用，并可能有助于选择性激活细胞内信号通路的假设是一致的。
RGS (regulators of G protein signaling) proteins are GTPase-activating proteins for the Galpha subunits of heterotrimeric G proteins and act to regulate signaling by rapidly cycling G protein. RGS proteins may integrate receptors and signaling pathways by physical or kinetic scaffolding mechanisms. To determine whether this results in enhancement and/or selectivity of agonist signaling, we have prepared C6 cells stably expressing the mu-opioid receptor and either pertussis toxin-insensitive or RGS- and pertussis toxin-insensitive Galpha(o). We have compared the activation of G protein, inhibition of adenylyl cyclase, stimulation of intracellular calcium release, and activation of the ERK1/2 MAPK pathway between cells expressing mutant Galpha(o) that is either RGS-insensitive or RGS-sensitive. The mu-receptor agonist [D-Ala(2), MePhe(4),Gly(5)-ol]enkephalin and partial agonist morphine were much more potent and/or had an increased maximal effect in inhibiting adenylyl cyclase and in activating MAPK in cells expressing RGS-insensitive Galpha(o). In contrast, mu-opioid agonist increases in intracellular calcium were less affected. The results are consistent with the hypothesis that the GTPase-activating protein activity of RGS proteins provides a control that limits agonist action through effector pathways and may contribute to selectivity of activation of intracellular signaling pathways.