Signal integration via phospho-regulation of RhoGAPs

描述（由申请人提供）：多种细胞信号的整合对于几乎所有生物过程的精确时空协调至关重要。在实现信号整合和生物协调的调控机制中，被广泛使用的是蛋白质磷酸化。我们一直在研究特定蛋白磷酸化事件在控制细胞形态、粘附和迁移过程中的作用，这些过程是由Rho GTPases严格调节的。这些研究揭示了p190 Rho GTPase激活蛋白（GAPs； p190A和p190B）作为信号整合子的关键作用，其被各种细胞内激酶磷酸化似乎对其在各种细胞过程中的作用至关重要。我们的主要目标是对RhoGAP对Rho介导的细胞过程的调控有一个清晰的认识，这里提出的研究重点是解决p190 RhoGAP磷酸化在上游调控信号整合中的作用。提出以下目的：1)建立pkc介导的p190A RhoGAP磷酸化的调控功能。2)确定p190A在极化细胞迁移中的磷酸化调控作用。3)确定磷酸化调节蛋白与p190 FF结构域相互作用的功能作用。4)探讨p190B RhoGAP在细胞粘附过程中对IGF-1信号的调控作用。这4个目标反映了大量的初步数据，这些数据指出了p190 gap在调节各种细胞生物学和发育过程中的关键磷酸化事件。我们已经生成了该分析所需的绝大多数试剂，这有望揭示这些gap作为信号积分器或调节rho依赖的细胞过程（包括细胞迁移）的“巧合传感器”的作用的大量新见解。在人类癌症中，细胞迁移是一种重要的细胞活动，它在肿瘤发生过程中最致命的转移中所起的作用已被明确确立。通过确定影响细胞迁移的调节机制，最终应该有可能开发新的治疗策略来预防或控制癌症转移。

DESCRIPTION (provided by applicant): The integration of diverse cellular signals is critical to the precise spatial and temporal coordination of virtually all biological processes. Among the widely used regulatory mechanisms to achieve signal integration and biological coordination is protein phosphorylation. We have been investigating the role of specific protein phosphorylation events in controlling cell morphology, adhesion, and migration- processes that are stringently regulated by the Rho GTPases. These studies have revealed a critical role for the p190 Rho GTPase activating proteins (GAPs; p190A and p190B) as signal integrators whose phosphorylation by various intracellular kinases appears to be critical to its role in a variety of cellular processes. Our broad objective is to develop a clear understanding of the regulation of Rho- mediated cellular processes by the RhoGAPs, and the focus of the studies proposed here is to address the role of p190 RhoGAP phosphorylation in the integration of upstream regulatory signals. The following Aims are proposed: 1) To establish the regulatory function of PKC-mediated phosphorylation of p190A RhoGAP. 2) To establish a role for phospho-regulation of p190A in polarized cell migration. 3) To determine the functional role of phosphorylation-regulated protein interactions with the p190 FF domains. 4) To establish the regulation of p190B RhoGAP in IGF-1 signaling in cell adhesion. These 4 Aims reflect a large body of preliminary data that points to these critical phosphorylation events in the role of the p190 GAPs in regulating a variety of cell biological and developmental processes. We have generated the vast majority of reagents required for this analysis, which is expected to reveal substantial new insights into the role of these GAPs as signal integrators or "coincidence sensors" that regulate Rho-dependent cellular processes, including cell migration. Cell migration is an important cellular activity in the context of human cancers, where its role in metastasis, the most lethal aspect of the tumorigenic process, has been clearly established. By identifying regulatory mechanisms that affect cell migration, it should eventually be possible to develop novel therapeutic strategies to prevent or manage cancer metastasis. PUBLIC HEALTH RELEVANCE: The proposed studies address a fundamental issue in the biology of all normal and cancer cells, namely how do the various intracellular proteins integrate a variety of extracellular stimuli to properly "instruct" the cell to respond appropriately? By enhancing our understanding of how cancer cells respond to their environment, we may be able to develop strategies to disrupt the processes in these cells that contribute to their malignant properties of accelerated growth and metastatic spread.