REGULATION OF THE RAS TRANSFORMATION PATHWAY

RAS 转化途径的调节

• 批准号: 2429802
• 负责人: LAWRENCE A. QUILLIAM
• 金额: $ 10.9万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-06-01 至 1999-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2429802
• 关键词: athymic mouse; binding proteins; biological signal transduction; cell transformation; gene mutation; genetic regulation; growth factor receptors; guanine nucleotide binding protein; guanine nucleotide exchange factors; guanine nucleotides; guanosinetriphosphatase activating protein; guanosinetriphosphatases; intermolecular interaction; laboratory rabbit; oncogenes; protein sequence; protein structure function; proteins; tissue /cell culture; transcription factor

The Ras oncoproteins play a critical role in cell growth and differentiation, transducing signals from upstream protein tyrosine kinases (PTKs) to the nuclear transcriptional machinery. In recent years, considerable progress has been made in identifying additional proteins that relay growth stimulatory signals down the "ras pathway". However, interactions between existing proteins are only poorly understood, and it is clear that further regulatory molecules remain to be identified. The goal of this proposal is to characterize the mechanism(s) by which three critical members of the Ras pathway, GAP (GTPase-activating protein), GDS (guanine nucleotide dissociation stimulator), and GRB2 regulate Ras activity and to identify novel molecular associations required for their function. While pl20 GAP is clearly a negative regulator of ras function, its putative role as a downstream target and effector of ras signaling remains controversial. We have recently obtained evidence for such a role and have narrowed this property down to a region that includes the SH3 domain. We will further characterize the role of this region by isolation, deletion and mutational analysis, and identify putative downstream effector(s) of the Ras transformation pathway that interact with GAP-SH3. Recent biochemical and genetic evidence has implicated CDC25 homologs (mCDC25, mSOS1 and 2) as activators of ras function. However, beyond their function as stimulators of the GTP/GDP cycle, little is known about the biological consequences of their interaction with ras proteins. Therefore, we will establish the role of these ras GDSs in mediating normal and oncogenic ras functions, and determine whether deregulated GDS activity may cause transformation in the absence of ras mutations. Finally, recent studies have implicated GRB-2 as the critical link that transmits the mitogenic signal from activated receptor PTKs to ras, and acts to stimulate the SOS exchange factor. However, we have obtained preliminary evidence that the role of GRB2 in intracellular signaling may be more complex, and may involve interactions with proteins other than receptor-PTKs. We have proposed studies to clarify these additional functions of GRB2. Taken together, these studies will provide fundamental information on the mechanisms of Ras activation and may identify additional components involved in regulating the ras pathway.

Ras 癌蛋白在细胞生长和 分化，转导来自上游蛋白酪氨酸的信号 激酶 (PTK) 与核转录机制的关系。最近几年， 在鉴定其他蛋白质方面取得了相当大的进展 沿着“ras 途径”传递生长刺激信号。 然而， 人们对现有蛋白质之间的相互作用知之甚少，而且 显然，进一步的调控分子仍有待确定。这 该提案的目标是描述三个机制的特征 Ras 通路的关键成员、GAP（GTP 酶激活蛋白）、GDS （鸟嘌呤核苷酸解离刺激剂），GRB2 调节 Ras 活性并鉴定其所需的新分子关联 功能。 虽然 pl20 GAP 显然是 ras 功能的负调节因子，但它 作为 ras 信号下游靶点和效应器的假定角色仍然存在 有争议的。我们最近获得了此类作用的证据，并已 将此属性缩小到包含 SH3 域的区域。我们 将通过隔离、删除进一步表征该区域的作用 和突变分析，并确定假定的下游效应子 与 GAP-SH3 相互作用的 Ras 转化途径。 最近的生化和遗传证据表明 CDC25 同源物 （mCDC25、mSOS1 和 2）作为 ras 功能的激活剂。然而，超出了他们的 作为 GTP/GDP 循环的刺激器，人们对它知之甚少 它们与 ras 蛋白相互作用的生物学后果。所以， 我们将确定这些 ras GDS 在调节正常和 致癌 ras 功能，并确定 GDS 活性是否失调 在没有 ras 突变的情况下可能会导致转化。 最后，最近的研究表明 GRB-2 是 将促有丝分裂信号从激活的受体 PTK 传递至 ras，并且 起到刺激 SOS 交换因子的作用。然而，我们已经获得了 初步证据表明 GRB2 在细胞内信号传导中的作用可能 更复杂，可能涉及与除 受体-PTK。 我们提出了研究来澄清这些额外的 GRB2的功能。 总而言之，这些研究将提供有关 Ras 激活机制，并可能识别其他组件 参与调节 ras 通路。