Regulation of Rho Family GTPases by G Proteins

描述（由申请人提供）：异源三聚体G蛋白将多种信号从heptahetical膜结合受体传递到细胞内效应物。RGS（Regulator of G protein signaling）蛋白家族成员调节G蛋白介导的信号。单体GTP酶的Rho家族的成员控制肌动蛋白细胞骨架的组织并参与多种细胞功能。本研究的目的是通过异源三聚体G蛋白介导的信号通路来了解Rho家族GTPases的调控机制。在异三聚体G蛋白中，Galpha 12和Galpha 13参与细胞转化、神经突收缩或胚胎发育等细胞过程。Rho激活参与这些信号通路。该提案的直接目标是了解Galpha 12和Galpha 13调节Rho活性的生化机制。Rho家族GTP酶受鸟嘌呤核苷酸交换因子（GEF）调节。具有氨基末端RGS结构域的RhoGEFs（RGS-RhoGEFs）、p115 RhoGEF、LARG和PDZ-RhoGEF被鉴定为Galpha 12和Galpha 13的效应子。Galpha 12/13与这些RhoGEFs的RGS结构域相互作用并调节其RhoGEFs活性。p115和LARG的RGS结构域作为特异于Galpha 12和Galpha 13的GT3活化蛋白。将分析Galpha 12和Galpha 13调节RGS-RhoGEFs机制的结构基础。Galpha 12或Galpha 13及其与LARG的复合物的晶体结构将被解决。将表征涉及其功能相互作用的Galpha 12/13或LARG的区域。将研究LARG或PDZ-RhoGEF调节RhoGEF活性的生化机制。此外，将分析神经元细胞中的Galpha 12/13-LARG/PDZRhoGEF信号通路。Galpha 12-RhoGEF途径在C. elegans及其参与神经元功能和胚胎发育的研究。对该通路的生理意义进行了探讨。将使用遗传学和生物化学方法对秀丽线虫进行研究。

DESCRIPTION (provided by applicant): Heterotrimeric G proteins transduce a variety of signals from heptahetical membrane-bound receptors to intracellular effectors. Members of RGS (Regulator of G protein signaling) protein family regulate G protein mediated signals. Members of the Rho family of monomeric GTPases control the organization of the actin cytoskeleton and are involved in a variety of cellular functions. The objective of this proposal is to understand the mechanism of regulation of Rho family GTPases through heterotrimeric G protein-mediated signaling pathways. Among heterotrimeric G proteins, Galpha12 and Galpha13 participate in cellular processes such as cell transformation, neurite retraction, or embryonic development. Rho activation is involved in these signaling pathways. The immediate goal of this proposal is to understand biochemical mechanisms of regulation of the activity of Rho by Galpha12 and Galpha13. Rho family GTPases are regulated by guanine nucleotide exchange factors (GEFs). RhoGEFs with amino terminal RGS domain (RGS-RhoGEFs), p115RhoGEF, LARG, and PDZ-RhoGEF, were identified to function as effectors for Galpha12 and Galpha13. Galpha12/13 interacts with RGS domain of these RhoGEFs and regulates their RhoGEF activity. RGS domains of p115 and LARG act as GTPase activating proteins specific for Galpha12 and Galpha13. The structure basis of the mechanism of regulation of RGS-RhoGEFs by Galpha12 and Galpha13 will be analyzed. The crystal structures of Galpha12 or Galpha13 and its complex with LARG will be solved. The regions of Galpha12/13 or LARG that are involved in their functional interaction will be characterized. The biochemical mechanisms of regulation of RhoGEF activity of LARG or PDZ-RhoGEF will be investigated. Furthermore, Galpha12/13-LARG/PDZRhoGEF signaling pathway in neuronal cells will be analyzed. Galpha12-RhoGEF pathway was identified in C. elegans and its involvement in neuronal function and embryonic development was demonstrated. The physiological significance of this pathway in C. elegans will be investigated using genetical and biochemical methods.