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细胞过程，其在控制细胞生长和发育中具有显著特征。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与人类疾病（包括癌症）的发展有关。虽然转录控制和泛素介导的蛋白水解通常被认为是不同的事件，最近令人兴奋的发现直接连接这些过程中的基因表达的控制：泛素化的转录因子已被证明是其功能所需的，和蛋白酶体本身已被证明参与RNA聚合酶II的转录。这些过程的联系揭示了我们渴望探索的转录控制的一个以前未预料到的方面。本提案中描述的实验将探讨泛素-蛋白酶体途径如何调节基因表达，特别强调理解激活剂泛素化在转录调控中的作用。为了实现这一目标，我们将在酵母和人类细胞系统中采用遗传和生物化学方法的组合。我们将研究泛素介导的天然酵母激活剂的蛋白水解如何影响其激活转录的能力。我们将通过研究嵌合激活因子来了解转录因子何时以及如何被泛素化，并揭示泛素化调节转录因子活性的基本机制。最后，我们将建立在我们的转录因子泛素化的分析，解决的作用，蛋白酶体在基因控制中发挥作用。这些研究的结果将提供有价值的洞察如何转录和泛素-蛋白酶体途径相互作用，并将作为一个范例，为我们理解这一新的层面在转录控制。

DESCRIPTION (provided by applicant): Transcriptional regulation and ubiquitin-mediated proteolysis are cellular 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 have been implicated in the development of human diseases, including cancer. Although transcriptional control and ubiquitin-mediated proteolysis are generally thought of as distinct events, recent exciting discoveries have directly connected these processes in the control of gene expression: ubiquitylation of a transcription factor has been shown to be required for its function, and the proteasome itself has been shown to participate in transcription by RNA polymerase II. The connection of these processes reveals a previously unanticipated aspect of transcriptional control that we are anxious to explore. Experiments described in this proposal will probe how the ubiquitin-proteasome pathway regulates gene expression, with particular emphasis on understanding the role that activator ubiquitylation plays in transcriptional regulation. To achieve this objective, we will employ a combination of genetic and biochemical approaches in both yeast and human cell systems. We will study how ubiquitin-mediated proteolysis of a natural yeast activator impacts its ability to activate transcription. We will study chimeric activators to learn when and how transcription factors are ubiquitylated, and to reveal the fundamental mechanism through which ubiquitylation regulates transcription factor activity. And finally, we will build on our analysis of transcription factor ubiquitylation by addressing the role that the proteasome plays in gene control. Results of these studies will provide valuable insight into how transcription and the ubiquitin-proteasome pathway interact, and will serve as a paradigm for our understanding of this new dimension in transcriptional control.