RAS GENES BY DOMINANT NEGATIVE MUTANTS

研究表明，激活的ras基因在许多肿瘤的发生、发展中起着重要作用。 人类肿瘤的种类直接ras基因家族由三个 成员，H-ras，K-ras和N-ras。ras基因属于一组 这些蛋白质统称为鸟嘌呤核苷酸结合蛋白。 鸟嘌呤-核苷酸结合蛋白需要鸟嘌呤-核苷酸进行其 适当的功能，并共享其中的几个保守的功能。许多 鸟嘌呤-核苷酸结合蛋白参与转导刺激 因此，可以想象，ras基因可能是一种 产品具有相似的生物学作用。目前，我们所知不多， ras基因的信号转导途径。除了明显的 在细胞增殖中的作用，ras基因也被证明可以诱导 某些细胞类型的终末分化，如大鼠嗜铬细胞瘤 细胞系PC 12，体外神经元细胞模型。 最近，我们描述了一类H-ras突变体，其可以显性地 抑制c-H-ras基因以及其他几种癌基因的作用， 例如SRC、FMS、SIS和FES。这种反式显性遗传的基础 抑制可能归因于基本元素的螯合 c-H-ras激活所必需的。这些变种人将提供一个 研究ras信号转导通路的有用工具 ras基因与其他癌基因的相互作用。我们提出 研究反式显性抑制的潜在机制， 也利用这些突变体的反式显性特性来研究 ras基因的生物学作用 1.我们将确定H-ras p2 l蛋白的物理需求， 反式显性抑制; 2.我们将确定K-ras（或 N-ras）c-H-ras和如前所述的其他癌基因上的突变体; 3. 我们将利用反式显性突变体作为亲和探针， 纯化与ras p2 l蛋白相互作用的元件; 4.我们将 研究ras p2 l蛋白在PC 12细胞分化中的作用 反式显性突变体

It has been demonstrated that activated ras genes play vital roles in many types of human tumor. The immediate ras gene family consists of three members, H-ras, K-ras and N-ras. The ras genes belong to a group of proteins collectively called guanine-nucleotide binding proteins. Guanine-nucleotide binding proteins require guanine-nucleotides for their proper functions and share several conserved features among them. Many guanine-nucleotide binding proteins are involved in transducing the stimuli signals to their targets; therefore, it is conceivable that the ras gene products have similar biological roles. At present, not much is known about the signal transduction pathway of ras genes. In addition to their apparent role in cell proliferation, ras genes also have been shown to induce terminal differentiation in some cell types, such as rat pheochromocytoma cell line PC12, a in vitro neuronal cell model. Recently, we have described a class of H-ras mutants which can dominantly suppress the action of the c-H-ras gene as well as several other oncogenes, such as src, fms, sis and fes. The basis for this type of trans-dominant suppression might be attributed to sequestering of the essential element required for c-H-ras activation. These mutants will provide an extremely valuable tool for investigating the signal transduction pathway of ras genes and the interactions of ras genes with other oncogenes. We propose to study the underlying mechanism of trans-dominant suppression and will also utilize the trans-dominant properties of these mutants to study the biological role of the ras genes. 1. We will determine the physical requirements of the H-ras p2l protein for trans-dominant suppression; 2. we will determine the effects of K-ras (or N-ras) mutants on c-H-ras and other oncogenes as mentioned previously; 3. we will utilize the trans-dominant mutants as the affinity probe for purifying the element that interacts with ras p2l protein and 4. we will investigate the role of the ras p2l protein in differentiating PC12 cells by trans-dominant mutants.