Ric-8A potentiates Gq-mediated signal transduction by acting downstream of G protein-coupled receptor in intact cells
Ric-8A potentiates Gq-mediated signal transduction by acting downstream of G protein-coupled receptor in intact cells
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DOI：
10.1111/j.1365-2443.2006.00959.x
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发表时间：
2006-05-01
期刊：
影响因子：
2.1
通讯作者：
Itoh, H
中科院分区：
文献类型：
--
作者：
Nishimura, A;Okamoto, M;Itoh, H
RIC-8最初是在对秀丽隐杆线虫对乙酰胆碱酯酶抑制剂具有抗性的突变体的遗传研究中发现的，据报道在体外作为G蛋白α亚基的鸟嘌呤核苷酸交换因子。然而，在完整细胞中，哺乳动物同源物Ric-8A对G蛋白偶联受体信号传导的生理作用在很大程度上是未知的。我们利用酵母与G α q的双杂交系统分离了ricc - 8a，并检测了ricc - 8a在gq介导的信号传导中的作用。Ric-8A的小干扰RNA降低了gq偶联受体介导的ERK活化和293T细胞内钙动员。Ric-8A在gq偶联受体刺激下易位到细胞膜上。肉豆肉酰化序列结合的Ric-8A突变体位于细胞膜上，并增强了gq偶联受体介导的ERK激活。此外，这种对ERK活化的增强和rick - 8a对G α q的鸟嘌呤核苷酸交换活性被Gq选择性抑制剂YM-254890抑制。这些结果表明，在完整细胞中，Ric-8A作为一种新型调节剂，增强了gq介导的信号转导。
RIC-8 was originally found by genetic studies on C. elegans mutants that were resistant to inhibitors of acetylcholinesterase and reported to act in vitro as a guanine nucleotide exchange factor for G protein alpha subunits. However, the physiological role of a mammalian homolog Ric-8A on G protein-coupled receptor signaling in intact cells is largely unknown. We isolated Ric-8A using a yeast two-hybrid system with G alpha q and examined the role of Ric-8A on Gq-mediated signaling. The small interfering RNA of Ric-8A diminished the Gq-coupled receptor-mediated ERK activation and intracellular calcium mobilization in 293T cells. Ric-8A was translocated to the cell membrane in response to the Gq-coupled receptor stimulation. The expression of the myristoylation sequence-conjugated Ric-8A mutant was located in the membranes and shown to enhance the Gq-coupled receptor-mediated ERK activation. Moreover, this enhancement on ERK activation and the guanine nucleotide exchange activity of Ric-8A for G alpha q were inhibited by Gq selective inhibitor YM-254890. These results suggested that Ric-8A potentiates Gq-mediated signal transduction by acting as a novel-type regulator in intact cells.