BETA-TUBULIN AS A PROBE OF MICROTUBLE MORPHOGENESIS

β-微管蛋白作为微管形态发生的探针

• 批准号: 6200283
• 负责人: FRANK E SOLOMON
• 金额: $ 35.77万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6200283
• 关键词: Saccharomyces; cell cycle; cytotoxicity; gene expression; genetic regulation; histogenesis; microtubules; protein biosynthesis; protein sequence; protein structure function; tissue /cell culture; transfection; tubulin

Microtubules are essential to cell growth, morphology and motility. They are filaments that the cell organizes into quite different structures depending upon which of those functions they are performing. The filaments themselves are primarily polymers of subunits of tubulin heterodimers. The heterodimers in turn are composed of one alpha-tubulin and one beta-tubulin polypeptide. The free tubulin polypeptides can occur when the heterodimer dissociates or when it does not form properly. At each of these levels - organization of the microtubules, polymerization of the subunits, and formation of the heterodimer - there are cellular regulatory mechanisms. Our work focuses on the lowest of these levels - the formation of the heterodimer and its regulation. Our interest in this issue arises from several observations in yeast cells. First, several genetic tests of microtubule function performed by our lab and others identify genes that affect this process. Second, we have shown that even small amounts of beta-tubulin polypeptide that is not incorporated into heterodimer and therefore is free, are toxic to the cell. There are genes which function to protect the cell against beta-tubulin toxicity. Third, we have recently identified a cellular mechanism that decreases expression of tubulin, perhaps in response to the formation of free tubulin polypeptides. These results provide evidence for regulation of very early steps in microtubule morphogenesis. Our long-range objective is to understand the mechanism of this regulation and its biological implications. This proposal will identify the molecular trigger of this regulatory process as well as the downstream targets of that trigger. In this way, it will identify the molecular mechanism of action. It will also investigate why free beta-tubulin polypeptides are toxic, and so identify the molecular process disrupted by that protein. Based on these results, the focus will shift to determining if similar mechanisms exist in animal cells. The results will provide basic information about the control of early steps in microtubule morphogenesis as part of the normal cell cycle and provide insight into response to those anti-cancer drugs that act by poisoning microtubule assembly.

微管对细胞的生长、形态和运动是必不可少的。 它们是细胞组织成完全不同的结构的细丝，这取决于它们执行的功能。 丝本身主要是微管蛋白异源二聚体亚基的聚合物。 异二聚体又由一个α-微管蛋白和一个β-微管蛋白多肽组成。游离微管蛋白多肽可在异二聚体解离时或在异二聚体未正确形成时出现。 在这些水平中的每一个-微管的组织，亚基的聚合和异二聚体的形成-都存在细胞调节机制。我们的工作集中在这些水平中的最低水平-异二聚体的形成及其调节。 我们对这个问题的兴趣来自于对酵母细胞的几次观察。 首先，我们实验室和其他实验室进行的几项微管功能的基因测试确定了影响这一过程的基因。 第二，我们已经表明，即使是少量的β-微管蛋白多肽，没有掺入异源二聚体，因此是免费的，是有毒的细胞。 有一些基因的功能是保护细胞免受β-微管蛋白的毒性。 第三，我们最近已经确定了一种细胞机制，减少微管蛋白的表达，可能是响应于游离微管蛋白多肽的形成。 这些结果为微管形态发生的早期调控提供了证据。我们的长期目标是了解这种调节的机制及其生物学意义。 该提案将确定该调节过程的分子触发器以及该触发器的下游靶点。 通过这种方式，它将确定作用的分子机制。 它还将研究为什么游离的β-微管蛋白多肽是有毒的，从而确定被该蛋白质破坏的分子过程。 基于这些结果，重点将转移到确定动物细胞中是否存在类似的机制。 这些结果将提供有关控制微管形态发生早期步骤的基本信息，作为正常细胞周期的一部分，并提供对那些通过毒害微管组装起作用的抗癌药物的反应的见解。