Transcription Control by the Ubiquitin-Proteasome System

描述（由申请人提供）：转录调节和泛素介导的蛋白水解是在细胞生长和发育控制中具有显著特征的两个过程。与它们在维持细胞内稳态中的关键作用一致，转录和泛素介导的蛋白质破坏的失调是包括癌症在内的多种人类疾病的核心。乍一看，这两个过程显然没有什么共同点转录是任何蛋白质生命的第一步，蛋白质水解是最后一步。尽管这些过程的不同性质，然而，越来越多的证据表明，泛素-蛋白酶体系统的组件直接参与基因表达的调控。这些过程之间的联系揭示了一个我们急于探索的先前未预料到的转录控制水平。该建议定义了一个研究策略，以调查如何泛素依赖的过程中调节的三个关键球员的转录调控转录激活因子，RNA聚合酶和组蛋白的活动。这些研究将与蛋白酶体组分在基因活化中的作用的高度整合分析相补充。为了实现这一目标，我们将采用遗传和生物化学方法的组合，使用模式生物酿酒酵母。我们将研究如何泛素化的原型酵母激活Gal 4连接转录激活所需的事件共转录前信使RNA加工。我们将研究RNA聚合酶II的最大亚基的泛素化如何调节聚合酶活性和亚基组成，以及组蛋白H2 B的泛素化如何调节组蛋白动力学和染色质与核环境的相互作用。最后，我们将研究蛋白酶体亚基是如何被募集到染色质中的，以及它们在基因激活和转录沉默中的功能。这些研究的结果将提供有价值的洞察如何转录和泛素-蛋白酶体系统相交，并将作为一个范例，为我们理解这个新的层面在转录控制。重要的是，我们的工作还将为理解这些过程如何导致人类疾病提供一个知识框架，并有可能通过调节泛素系统的活性来确定调节异常转录的方法;这一策略可以很好地形成改进癌症治疗的基础。

DESCRIPTION (provided by applicant): Transcriptional regulation and ubiquitin-mediated proteolysis are two processes that feature prominently in the control of cell growth and development. Consistent with their pivotal roles in maintaining cellular homeostasis, deregulation of both transcription and ubiquitin-mediated protein destruction lies at the heart of a variety of human diseases, including cancer. At first blush, these two processes have apparently very little in common-transcription is the first step in the life of any protein; proteolysis is the last. Despite the disparate nature of these processes, however, a growing body of evidence suggests that components of the ubiquitin-proteasome system are directly involved in the regulation of gene expression. The connection of these processes reveals a previously unanticipated level of transcriptional control that we are anxious to explore. This proposal defines a research strategy to investigate how ubiquitin-dependent processes regulate the activity of three key players in transcriptional regulation-transcriptional activators, RNA polymerase, and histones. These studies will be complemented with a highly-integrated analysis of the role of proteasome components in gene activation. To achieve this objective, we will employ a combination of genetic and biochemical approaches using the model organism Saccharomyces cerevisiae. We will study how ubiquitylation of the prototypical yeast activator Gal4 connects transcriptional activation to events required for co-transcriptional pre-messenger RNA processing. We will investigate how ubiquitylation of the largest subunit of RNA polymerase II regulates polymerase activity and subunit composition, and how ubiquitylation of histone H2B modulates histone dynamics and interaction of chromatin with the nuclear environment. And, finally, we will study how proteasome subunits are recruited to chromatin and their function in both gene activation and transcriptional silencing. Results of these studies will provide valuable insight into how transcription and the ubiquitin-proteasome systems intersect, and will serve as a paradigm for our understanding of this new dimension in transcriptional control. Importantly, our work will also provide an intellectual framework for understanding how these processes contribute to human disease, and offers the potential to identify ways to regulate aberrant transcription by modulating the activity of the ubiquitin system; a strategy that could very-well form the basis of improved cancer therapies.