Rnd Effector Molecules in Epithelial Cell Transformation

描述（由申请人提供）： 小GT3 Ras将信号从活化的细胞表面受体传递到细胞内信号传导途径。在起源于极化上皮细胞的腺癌中，Ras信号转导通常由于激活突变或基因扩增而失调。致癌Ras介导极化上皮细胞转化的机制尚不清楚。Ras信号传导的主要效应子途径是Raf-MEK-ERK途径，其模拟Ras对细胞的许多作用。在极化上皮细胞中激活的Ras或Raf的表达导致肌动蛋白细胞骨架的深刻改变和细胞结构的相关变化。肌动蛋白细胞骨架受Rho家族GTP结合蛋白的控制。Ras或Raf激活极化上皮细胞导致诱导表达的Rho样蛋白Rnd 3，这似乎是作为一个内源性拮抗剂Rho蛋白。因此，Rnd蛋白对细胞的作用被Rho蛋白的活化形式的表达抵消。事实上，对Rnd信号的效应分子一无所知。识别Rnd蛋白的效应子是重要的，因为它们在细胞中的表达产生了表明它们在细胞转化和发育过程中起关键作用的表型。在新的研究中，我们已经确定了Rho GT3激活蛋白p190作为Rnd信号转导的假定效应分子。目的1是剖析Rnd和p190蛋白之间的相互作用并产生这种相互作用的抑制分子。目的2是测试的假设，Rnd和p190分子之间的相互作用影响的p190分子的功能结构域，和p190是一个效应分子的Rnd蛋白在体内使用细胞中，其中p190已被敲除。目的3解决了Rnd-p190相互作用是否是通过Ras激活的Raf-MEK-ERK途径使用在目的1中产生的抑制性分子的极化上皮的致癌转化的关键。总之，拟议的研究将阐明Ras转化上皮细胞导致侵袭和转移的机制。

DESCRIPTION (provided by applicant): The small GTPase Ras relays signals from activated cell surface receptors to intracellular signaling pathways. In adenocarcinomas, which originate from polarized epithelial cells, Ras signaling is often deregulated as a result of activating mutations or gene amplification. The mechanisms by which oncogenic Ras elicits transformation of polarized epithelial cells are poorly understood. A major effector pathway of Ras signaling is the Raf-MEK-ERK pathway, which mimics numerous effects of Ras on cells. Expression of activated Ras or Raf in polarized epithelial cells leads to profound alterations in the actin cytoskeleton and associated changes in cellular architecture. The actin eytoskeleton is subject to control by Rho family GTP-binding proteins. Ras or Raf activation in polarized epithelial cells leads to induced expression of the Rho-like protein Rnd3, which appears to function as an endogenous antagonist to Rho proteins. Accordingly, effects of Rnd proteins on cells are counteracted by expression of activated forms of Rho proteins. Virtually nothing is known about effector molecules of Rnd signaling. It is important to identify effectors of Rnd proteins as their expression in cells elicits a phenotype that suggests that they play key roles in cell transformation and developmental processes. In new studies we have identified the Rho GTPase activating protein p190 as a putative effector molecule of Rnd signaling. Aim 1 is to dissect the interaction between Rnd and p190 proteins and to generate an inhibitory molecule of this interaction. Aim 2 is to test the hypothesis that the interaction between Rnd and p190 molecules affects functional domains of the p190 molecule, and that p190 is an effector molecule of Rnd proteins in vivo using cells in which p190 has been knocked out. Aim 3 addresses whether the Rnd-p190 interaction is critical to oncogenic transformation of polarized epithelial by the Ras activated Raf-MEK-ERK pathway using the inhibitory molecule generated in Aim 1. Together, the proposed studies will elucidate mechanisms whereby Ras transforms epithelial cells leading to invasion and metastasis.