Regulation of intracellular calcium by a signalling complex of IRAG, IP3 receptor and cGMP kinase Iβ
Regulation of intracellular calcium by a signalling complex of IRAG, IP3 receptor and cGMP kinase Iβ
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DOI：
10.1038/35004606
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发表时间：
2000-03-09
期刊：
影响因子：
64.8
通讯作者：
Ruth, P
中科院分区：
文献类型：
--
作者：
Schlossmann, J;Ammendola, A;Ruth, P
内质网释放的钙控制许多细胞过程，包括平滑肌和其他细胞的增殖和收缩（1，2）。从肌醇1，4，5-三磷酸（IP 3）-敏感性储存中释放的钙通过钙调蛋白与IP 3受体（IP 3R）（3，4）和NO/cGMP/cGMP激酶I（cGKI）信号传导途径（5，6）的结合而负调节。cGKI的激活降低了IP 3刺激的细胞内钙升高（7），诱导平滑肌松弛（8），并有助于NO/cGMP的抗增殖（9）和促凋亡作用（10）。在这里，我们表明，在微粒体平滑肌膜，cGKI β磷酸化的IP 3R和cGKI β，和相对分子质量为125，000的蛋白质，我们现在确定为IP 3R相关的cGMP激酶底物（IRAG）。这些蛋白质通过针对cGKI、IP 3R或IRAG的抗体共免疫沉淀。在COS-7细胞中异源表达后，IRAG定位于细胞核周围。缓激肽刺激的钙释放不受IRAG或cGKI β表达的影响，我们在cGMP存在和不存在的情况下进行了测试。然而，在cGMP存在下，IRAG和cGKI β共表达后，钙释放受到抑制。这些结果将IRAG鉴定为IP 3诱导的钙释放的必需NO/cGKI依赖性调节剂。
Calcium release from the endoplasmic reticulum controls a number of cellular processes, including proliferation and contraction of smooth muscle and other cells(1,2). Calcium release from inositol 1,4,5-trisphosphate (IP3)-sensitive stores is negatively regulated by binding of calmodulin to the IP3 receptor (IP3R)(3,4) and the NO/cGMP/cGMP kinase I (cGKI) signalling pathways(5,6). Activation of cGKI decreases IP3-stimulated elevations in intracellular calcium(7), induces smooth muscle relaxation(8) and contributes to the antiproliferative(9) and pro-apoptotic effects of NO/cGMP(10). Here we show that, in microsomal smooth muscle membranes, cGKI beta phosphorylated the IP3R and cGKI beta, and a protein of relative molecular mass 125,000 which we now identify as the IP3R-associated cGMP kinase substrate (IRAG). These proteins were co-immunoprecipitated by antibodies directed against cGKI, IP3R or IRAG. IRAG was found in many tissues including aorta, trachea and uterus, and was localized perinuclearly after heterologous expression in COS-7 cells. Bradykinin-stimulated calcium release was not affected by the expression of either IRAG or cGKI beta, which we tested in the absence and presence of cGMP. However, calcium release was inhibited after co-expression of IRAG and cGKI beta in the presence of cGMP. These results identify IRAG as an essential NO/cGKI-dependent regulator of IP3-induced calcium release.