Regulation of c-Raf-1 by Ras and Growth Factors

Ras 和生长因子对 c-Raf-1 的调节

• 批准号: 6561581
• 负责人: GURI TZIVION
• 金额: $ 26.19万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6561581
• 关键词: SDS polyacrylamide gel electrophoresis; animal extract; antineoplastics; biological signal transduction; cell cycle proteins; cell transformation; chimeric proteins; gene deletion mutation; growth factor; growth inhibitors; guanine nucleotide binding protein; immunoprecipitation; mitogen activated protein kinase; phosphorylation; protein binding; protein protein interaction; protein structure function; protein transport; protooncogene; transfection; western blottings

DESCRIPTION (provided by applicant): The Ras-Raf-MAPK pathway regulates many physiological processes by transmitting signals from membrane-bound receptors to nuclear and cytoplasmic targets that coordinate cellular response to a variety of factors, such as growth, stress, survival and inflammation. Aberrations in this pathway result in abnormal growth and proliferation, and in many cases, cause malignant transformation. The high frequency of activating Ras mutations found in various human cancers, together with the well-documented role of Raf in numerous physiological processes, make the Ras-Raf-MAPK pathway a prime target for drug development for various cancers, inflammation and other aliments, c-Raf-1, a cellular protooncogene also found in transforming viruses, is the primary Ras effector for MAPK activation and is a major and indispensable part of the Ras-MAPK cascade. Although many laboratories have been studying Raf regulation, many aspects of this highly complex mechanism remain unknown. Published work by the applicant and preliminary results presented in this proposal help to unravel several of these aspects and provide a novel approach for inhibiting Raf activity. The objectives of the present application are to further the understanding of Raf regulation, focusing on specific roles of Ras and phosphorylation in Raf regulation, and to develop a useful in vivo Raf inhibitor based on a potent in vitro Raf inhibitor, described in this application. These objectives will be accomplished by pursuing the following three specific alms: 1. Characterize the role of Ras in the Raf-1 activation process. Attention will be given to distinguishing between the roles of Ras in recruiting Raf to the membrane and displacing 14-3-3, and to the role of Ras-Ras and Raf-Raf dimerization in the activation process. 2. Determine the role of Raf-1 S471 and T481 sites in Rat regulation and function. This aim will be accomplished by examining the regulation of S471 and T481 phosphorylation and by evaluating the functional significance of their substitution and phosphorylation. 3. Characterize the mechanism underlying Raf inhibition by the Raf-1 inhibitor peptide, and identify peptide-delivery methods allowing inhibition of cellular Raf-1 in vivo. The proposed study will enhance our understanding of Raf regulation by providing molecular details on the role of Ras and newly identified Raf phosphorylation sites in Raf activation. In addition, the proposed study offers the prospect for developing an in vivo Raf inhibitor, which in addition to being a highly useful research tool, would provide a basis for developing therapeutic agents for diseases involving excessive cell proliferation such as cancer and inflammation.

描述（由申请人提供）：Ras-Raf-MAPK通路通过将信号从膜结合受体传递到核和细胞质靶标来调节许多生理过程，这些靶标协调细胞对多种因素的反应，如生长、应激、生存和炎症。该通路的异常导致异常生长和增殖，并在许多情况下引起恶性转化。在各种人类癌症中发现的激活Ras突变的高频率，以及Raf在许多生理过程中的良好作用，使Ras-Raf-MAPK途径成为各种癌症，炎症和其他营养物质的药物开发的主要靶点。c-Raf-1，一种也在转化病毒中发现的细胞原癌基因，是MAPK激活的主要Ras效应物，是Ras-MAPK级联反应的主要和不可或缺的部分。尽管许多实验室一直在研究Raf调控，但这种高度复杂机制的许多方面仍然未知。申请人发表的工作和本提案中提出的初步结果有助于解开这些方面的几个问题，并提供了抑制Raf活性的新方法。本应用的目的是进一步了解Raf调控，重点关注Ras和磷酸化在Raf调控中的具体作用，并在本应用中描述的有效体外Raf抑制剂的基础上开发一种有用的体内Raf抑制剂。这些目标将通过以下三种具体施舍来实现：描述Ras在Raf-1激活过程中的作用。重点将放在区分Ras在招募Raf到膜和置换14-3-3中的作用，以及Ras-Ras和Raf-Raf二聚化在激活过程中的作用。2. 确定Raf-1 S471和T481位点在大鼠调控和功能中的作用。这一目标将通过检查S471和T481磷酸化的调控以及通过评估它们的取代和磷酸化的功能意义来实现。3. 表征Raf-1抑制剂肽抑制Raf的机制，并确定体内抑制细胞Raf-1的肽递送方法。该研究将通过提供Ras和新发现的Raf磷酸化位点在Raf活化中的作用的分子细节，增强我们对Raf调控的理解。此外，该研究为开发体内Raf抑制剂提供了前景，这除了是一种非常有用的研究工具外，还将为开发涉及过度细胞增殖的疾病（如癌症和炎症）的治疗剂提供基础。