FUNCTION OF THE RETINOBLASTOMA PROTEIN

视网膜母细胞瘤蛋白的功能

• 批准号: 2101376
• 负责人: EDWARD E HARLOW
• 金额: $ 39.62万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-05 至 1998-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2101376
• 关键词: DNA binding protein; cell cycle; cell differentiation; cell transformation; gene expression; genetic regulation; laboratory mouse; laboratory rabbit; microinjections; nuclear runoff assay; oncogenes; phosphorylation; protein kinase; protein structure function; retinoblastoma; tissue /cell culture; transcription factor; transfection

A normal cell undergoes many mutations during tumorigenesis. One of the features of this process is the loss of control over proliferation. Typically this loss is the result of mutations in two types of genes, oncogenes and tumor suppressor genes. The products of oncogenes normally act to promote cell division, and mutation of these genes leads to inappropriate signals to divide. The protein products of tumor suppressor genes act to limit the proliferation of a normal cell. During tumorigenesis these genes are often inactivated through mutation, and it is the loss of tumor suppressor gene products that contributes to increased proliferation. One of the first tumor suppressor genes to be isolated was the retinoblastoma susceptibility gene, RB-1. Retinoblastomas characteristically contain two rate limiting mutations, one in each allele of RB-1. In familial retinoblastomas, one mutant allele is inherited and the other develops during somatic development of the retina. In sporadic retinoblastomas, both mutations occur during somatic development. RB-1 mutations have also been found in a wide variety of other human tumors. This work leads to the conclusion that the product of the RB-1 gene negatively regulates proliferation of many different types of cell. Recent studies of the protein product of the RB-1 gene (pRB) have provided the first clues to its function. It is a nuclear protein whose normal role appears to be the regulation of certain cellular transcription factors. The best characterized partner for pRB is the transcription factor E2F. E2F appears to regulate the transcription of a set of genes whose expression is required for cell proliferation. Current evidence suggests that pRB represses E2F-mediated transcription and thereby contributes to the regulation of key genes. This interaction appears to be only one component of E2F regulation. There is strong evidence that the activity of E2F is also regulated by its association with the pRB-related protein p107. pRB and p107 share many properties. They both were originally identified through their interactions with DNA tumor virus oncoproteins. Viral proteins, including adenovirus E1A, SV40 large T, and human papillomavirus E7, all target pRB and p107 as a portion of their transforming ability. In these cases, E1A, large T, and E7 inactivate pRB and p107, thus mimicking the loss of pRB in human tumors. This grant proposes to investigate how pRB, p107 and E2F combine to give regulated transactivation and to determine the biological consequences of these interactions. Our immediate goals are threefold. First, we need to understand the details of pRB/E2F regulation. This work is currently underway and encompasses the biochemistry of pRB/E2F regulation, the determination of the effects of upstream regulators and the analysis of downstream targets. The second main goal is to determine how p107 affects E2F transcription. Most of the reagents needed for these studies are now available and we have established the basic assays. The biological consequences of these interactions are our third goal. Here, we will determine how these proteins contribute to the regulation of cell proliferation, differentiation, and oncogenesis.

正常细胞在肿瘤发生过程中会经历许多突变。 中的一个 这一过程的特点是失去对扩散的控制。 通常这种损失是两种基因突变的结果， 癌基因和抑癌基因。 通常癌基因的产物 促进细胞分裂，这些基因的突变会导致 不适当的信号来划分。 肿瘤蛋白产物 抑制基因的作用是限制正常细胞的增殖。 期间 在肿瘤发生过程中，这些基因通常会因突变而失活，并且 是肿瘤抑制基因产物的丢失导致 增殖增加。 最早发现的抑癌基因之一 分离出视网膜母细胞瘤易感基因RB-1。 视网膜母细胞瘤的特征是含有两种限速突变， RB-1 的每个等位基因中都有一个。 在家族性视网膜母细胞瘤中，一种突变体 等位基因是遗传的，另一个在体细胞发育过程中发育 视网膜。 在散发性视网膜母细胞瘤中，两种突变均发生在 躯体发育。 RB-1 突变也广泛存在于 各种其他人类肿瘤。 这项工作得出的结论是 RB-1基因的产物负调控许多细胞的增殖 不同类型的细胞。 最近对 RB-1 基因 (pRB) 的蛋白质产物的研究 提供了其功能的第一条线索。 它是一种核蛋白，其 正常作用似乎是调节某些细胞 转录因子。 pRB 的最佳特征伙伴是 转录因子E2F。 E2F似乎调节转录 细胞增殖所需表达的一组基因。 目前的证据表明 pRB 抑制 E2F 介导的转录 从而有助于关键基因的调控。 这次互动 似乎只是 E2F 监管的一个组成部分。 有很强的 有证据表明 E2F 的活动也受到其关联的调节 与 pRB 相关蛋白 p107。 pRB 和 p107 有许多相同的特性。 两人最初被认定为 通过它们与 DNA 肿瘤病毒癌蛋白的相互作用。 病毒性的 蛋白质，包括腺病毒 E1A、SV40 大 T 和人类 乳头瘤病毒 E7，均以 pRB 和 p107 作为其病毒的一部分 转化能力。 在这些情况下，E1A、大 T 和 E7 失活 pRB 和 p107，从而模拟人类肿瘤中 pRB 的丢失。 该资助计划研究 pRB、p107 和 E2F 如何结合起来提供 调节反式激活并确定生物学后果 这些相互作用。 我们的近期目标有三个。 首先，我们 需要了解pRB/E2F调节的细节。 这部作品是 目前正在进行中，涵盖 pRB/E2F 的生物化学 监管，确定上游监管机构的影响和 下游目标分析。 第二个主要目标是确定 p107 如何影响 E2F 转录。 大部分所需试剂 这些研究现已可用，我们已经建立了基本分析方法。 这些相互作用的生物学后果是我们的第三个目标。 在这里，我们将确定这些蛋白质如何促进调节 细胞增殖、分化和肿瘤发生。