G_<αh>/transglutaminase-2 activity is required for maximal activatio of adenylylcyclase 8 in human and rat g(n) lioma cells
G_<αh>/transglutaminase-2 activity is required for maximal activatio of adenylylcyclase 8 in human and rat g(n) lioma cells
复制标题
G_<αh>/转谷氨酰胺酶-2 活性是人和大鼠 g(n) lioma 细胞中腺苷酸环化酶 8 最大激活所必需的
DOI：
10.1016/j.cellsig.2012.11.021
复制
发表时间：
2013
期刊：
影响因子：
4.8
通讯作者：
Nakahata N.
中科院分区：
文献类型：
--
作者：
Obara Y;Yanagihata Y;Abe T;Dafik L;Ishii K;Nakahata N.
Gαh（或转谷氨酰胺酶-2 (TG2)）是一种与G蛋白偶联受体相关的非典型鸟嘌呤核苷酸结合蛋白。TG2还发挥谷氨酰胺转酶活性，催化翻译后蛋白交联，形成ε-（γ-谷氨酰基）赖氨酸或（γ-谷氨酰基）多胺键。本文详细探讨了g - αh/TG2在神经胶质细胞信号转导中的作用。在1321N1个缺乏g - αh/TG2的人星形细胞瘤细胞中，g - αh/TG2的过表达引起β-肾上腺素受体激动剂异丙肾上腺素或腺苷酸环化酶激活剂forskolin刺激cAMP积累增强。这种camp增强被TG2抑制剂ERW1069逆转。在表达内源性Gαh/TG2的大鼠C6胶质瘤细胞中，过表达缺乏谷氨酰胺转肽类酶活性的显性阴性突变体Gαh/TG2- c277v可显著抑制异丙肾上腺素或福斯可林诱导的cAMP积累，而不能结合GTP/GDP的Gαh/TG2- s171e突变体则不受其抑制。这些结果表明，g - αh/TG2通过其谷氨酰胺转氨酶活性而不是通过其g蛋白活性来增强腺苷酸环化酶活性。g - αh/TG2也增加了cAMP反应元件和白细胞介素-6启动子的活性，在两种胶质瘤细胞中都伴有cAMP的升高。由于腺苷酸环化酶8在cAMP的产生中起着重要作用，我们重点研究了g - αh/TG2对腺苷酸环化酶8的翻译后修饰。腺苷酸环化酶8在1321N1和C6细胞中均有表达；然而，g - αh/TG2既不影响腺苷基化酶8的表达水平、糖基化，也不影响二聚化状态。相反，戊胺作为Gαh/TG2的底物，以谷氨酰胺转氨酶活性依赖的方式被纳入腺苷酸环化酶8。综上所述，g - αh/TG2在胶质瘤细胞中促进cAMP的产生，同时介导腺苷酸环化酶8的修饰。
Gαh(or transglutaminase-2 (TG2)) is an atypical guanine nucleotide binding-protein that associates with G protein-coupled receptors. TG2 also exerts transglutaminase activity that catalyzes posttranslational protein cross-linking with the formation of ε-(γ-glutamyl) lysine or (γ-glutamyl) polyamine bonds. Here, the role of Gαh/TG2 in signal transduction in glial cells was examined in detail. In 1321N1 human astrocytoma cells that lack Gαh/TG2, overexpression of Gαh/TG2 caused an enhancement of cAMP accumulation stimulated with the β-adrenergic receptor agonist, isoproterenol, or the adenylylcyclase activator, forskolin. This cAMP-enhancement was reversed by the TG2 inhibitor, ERW1069. In rat C6 glioma cells that express endogenous Gαh/TG2, cAMP accumulation induced by isoproterenol or forskolin was significantly inhibited by overexpression of Gαh/TG2-C277V, a dominant-negative mutant that lacks transglutaminase activity, but was not inhibited by the Gαh/TG2-S171E mutant that cannot bind GTP/GDP. These results suggest Gαh/TG2 potentiates adenylylcyclase activity by its transglutaminase activity and not by its G-protein activity. Gαh/TG2 also increased the activities of the cAMP response element and interleukin-6 promoter, accompanied by an of cAMP in both glioma cells. Since adenylylcyclase 8 plays a major role in cAMP production, we focused on post-translational modification of adenylylcyclase 8 by Gαh/TG2. Adenylylcyclase 8 is expressed in both 1321N1 and C6 cells; however, Gαh/TG2 affected neither adenylylcyclase 8 expression levels, glycosylation, nor dimerization status. In contrast, pentylamine, a substrate of Gαh/TG2, was incorporated into adenylylcyclase 8 in a transglutaminase activity-dependent manner. Taking these results together, Gαh/TG2 promotes cAMP production accompanied by a modification of adenylylcyclase 8 in glioma cells.