Homo- and hetero-oligomerization of PDZ-RhoGEF, LARG and p115RhoGEF by their C-terminal region regulates their in vivo Rho GEF activity and transforming potential
Homo- and hetero-oligomerization of PDZ-RhoGEF, LARG and p115RhoGEF by their C-terminal region regulates their in vivo Rho GEF activity and transforming potential
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DOI：
10.1038/sj.onc.1207012
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发表时间：
2004-01-08
期刊：
影响因子：
8
通讯作者：
Gutkind, JS
中科院分区：
文献类型：
--
作者：
Chikumi, H;Barac, A;Gutkind, JS
PDZ-RhoGEF、LARG和p115 RhoGEF是新近发现的Rho-鸟嘌呤核苷酸交换因子（GEF）家族的成员，其具有与G蛋白信号调节因子（RGS）相似的结构特征。该RGS-like（RGL）结构域提供了功能基序，通过该功能基序，Ga（12）和Ga（13）可以结合并调节这些RhoGEF的活性，从而提供了从这些异源三聚体G蛋白到Rho的直接连接。PDZ-RhoGEF和LARG也可以被酪氨酸激酶（包括FAK）磷酸化，并通过其PDZ结构域与丛状蛋白B（一种在发育期间控制轴突引导的脑信号蛋白受体）缔合，从而刺激Rho。有趣的是，在表征PDZ-RhoGEF抗血清时，我们发现转染的PDZ-RhoGEF构建体与内源性PDZ-RhoGEF相关。事实上，我们观察到PDZ-RhoGEF和LARG可以形成同源和异源寡聚体，而p115 RhoGEF只能同源寡聚化，并且这种分子间相互作用是由其独特的C-末端区域介导的。PDZ-RhoGEF的C-末端尾部的缺失对体外GEF对Rho的催化活性没有显著影响，但导致刺激血清反应元件报告子的能力和体内GTP结合的Rho的积累急剧增加。此外，去除三个含有RGL的GEF中的每一个的C末端释放了它们的全部转化潜力。总之，这些发现表明存在一种新的机制控制PDZ-RhoGEF，LARG和p115 RhoGEF的活性，这涉及通过其抑制性C-末端区域的同源和异源寡聚化。
PDZ-RhoGEF, LARG, and p115RhoGEF are members of a newly identified family of Rho-guanine nucleotide exchange factors (GEFs) exhibiting a unique structural feature consisting of the presence of an area of similarity to regulators of G protein signaling (RGS). This RGS-like (RGL) domain provides a functional motif by which Galpha(12) and Galpha(13) can bind and regulate the activity of these RhoGEFs, thus providing a direct link from these heterotrimeric G proteins to Rho. PDZ-RhoGEF and LARG can also be phosphorylated by tyrosine kinases, including FAK, and associate with Plexin B, a semaphorin receptor, which controls axon guidance during development, through their PDZ domain, thereby stimulating Rho. Interestingly, while characterizing a PDZ-RhoGEF antiserum, we found that a transfected PDZ-RhoGEF construct associated with the endogenous PDZ-RhoGEF. Indeed, we observed that PDZ-RhoGEF and LARG can form homo- and hetero-oligomers, whereas p115RhoGEF can only homo-oligomerize, and that this intermolecular interaction was mediated by their unique C-terminal regions. Deletion of the C-terminal tail of PDZ-RhoGEF had no significant effect on the GEF catalytic activity towards Rho in vitro, but resulted in a drastic increase in the ability to stimulate a serum response element reporter and the accumulation of the GTP-bound Rho in vivo. Furthermore, removal of the C-termini of each of the three RGL-containing GEFs unleashed their full transforming potential. Together, these findings suggest the existence of a novel mechanism controlling the activity of PDZ-RhoGEF, LARG, and p115RhoGEF, which involves homo- and hetero-oligomerization through their inhibitory C-terminal region.