KSR, a Modifier of Ras Mediated Cell Transformation

KSR，Ras 介导的细胞转化的修饰剂

• 批准号: 7264382
• 负责人: Robert E. Lewis
• 金额: $ 3.35万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2008-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7264382
• 关键词: affinity chromatography; cell nucleus; cell transformation; cytoplasm; enzyme activity; fibroblasts; guanine nucleotide binding protein; intracellular transport; laboratory mouse; matrix assisted laser desorption ionization; mitogen activated protein kinase; phosphoproteins; phosphorylation; protein kinase; protein transport

DESCRIPTION (provided by applicant): Tumor formation in vivo and the in vitro transformation of cells cultured from primary tissues require multiples oncogenic events. These events result from the creation or introduction of dominant acting oncogenes and the inactivation of tumor suppressors. Susceptibility of a cell to the transforming properties of these genes may be modified by other cellular genes that, while not driving the oncogenic process, are necessary for the transduction of the transforming event. The central hypothesis of this proposal is that the protein product of the gene Kinase Suppressor of Ras (KSR) is a potent modifier of cell transformation by oncogenic Ras. The goal of this proposal is to explain the molecular mechanisms underlying the biological actions of this putative modifier. KSR was identified as a loss-of-function allele that suppresses the phenotype of activated Ras in Drosophila and C. elegans. These data indicated that normal KSR may be a positive regulator of Ras-regulated pathways in lower eukaryotes. Analysis of oncogenic Ras-mediated transformation in primary fibroblasts from KSR about mice indicate that KSR functions similarly in mammals. Additional analyses demonstrate that KSR is a specific effector of the Ras/Raf/MEK/ERK kinase cascade. KSR is phosphorylated, and mutation of a subset of these phosphorylation sites causes the redistribution of KSR from the cytoplasm to the nucleus. These observations have lead to the hypotheses that the phosphorylation of KSR determines its subcellular location and that the localization of KSR affects its ability to regulate the Ras/Raf/MEK/ERK kinase cascade and Ras-mediated cell transformation. These hypotheses will be tested by: 1) identifying the sequences in KSR that regulate its subcellular distribution; 2) determining the role of KSR phosphorylation in regulating the distribution of KSR between the cytoplasm and the nucleus; 3) characterizing the physical interaction of KSR with Raf, MEK and ERK and its biological consequences; and 4) determining how the contribution of KSR to cell transformation is affected by its subcellular distribution and phosphorylation.

描述（由申请人提供）：体内和体外肿瘤形成 从原代组织培养的细胞的转化需要多次 致癌事件。这些事件是由于创建或引入 显性作用癌基因和抑癌基因失活。 细胞对这些基因的转化特性的敏感性可能是 被其他细胞基因修饰，虽然不驱动致癌过程， 对于转化事件的转导是必需的。中央 该提议的假设是激酶基因的蛋白质产物 Ras 抑制剂 (KSR) 是细胞转化的有效调节剂 致癌Ras。该提案的目标是解释分子机制 这种假定的修饰剂的生物作用的基础。 KSR被认定 作为功​​能丧失等位基因，抑制激活 Ras 的表型 果蝇和线虫。这些数据表明正常的 KSR 可能是 低等真核生物中 Ras 调节途径的正调节因子。分析 致癌 Ras 介导的 KSR 原代成纤维细胞转化 小鼠表明 KSR 在哺乳动物中具有类似的功能。附加分析 证明 KSR 是 Ras/Raf/MEK/ERK 激酶的特异性效应子 级联。 KSR 被磷酸化，其中一部分发生突变 磷酸化位点导致 KSR 从细胞质重新分布到 核。这些观察结果导致了这样的假设： KSR 的磷酸化决定了其亚细胞位置，并且 KSR 的定位影响其调节 Ras/Raf/MEK/ERK 激酶的能力 级联和Ras介导的细胞转化。这些假设将被检验 通过：1) 鉴定 KSR 中调节其亚细胞的序列 分配; 2)确定KSR磷酸化在调节中的作用 KSR在细胞质和细胞核之间的分布； 3）表征 KSR与Raf、MEK和ERK的物理相互作用及其生物学 结果; 4) 确定 KSR 对细胞的贡献 转化受其亚细胞分布和磷酸化的影响。