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分解是细胞过程中突出的特点，控制细胞的生长和发育。转录的解除调控和泛素介导的蛋白质破坏与它们在维持细胞内稳态方面的关键作用一致，与包括癌症在内的人类疾病的发展有关。尽管转录控制和泛素介导的蛋白降解通常被认为是不同的事件，但最近令人兴奋的发现直接将这些过程与基因表达控制联系在一起：转录因子的泛素化被证明是其功能所必需的，蛋白酶体本身被证明参与了RNA聚合酶II的转录。这些过程的联系揭示了我们急于探索的转录控制的一个以前没有预料到的方面。本提案中描述的实验将探索泛素-蛋白酶体途径如何调节基因表达，特别强调了解激活剂泛素化在转录调节中所起的作用。为了实现这一目标，我们将在酵母和人类细胞系统中使用遗传和生化方法的组合。我们将研究泛素介导的天然酵母激活剂的蛋白分解如何影响其激活转录的能力。我们将研究嵌合激活子，以了解转录因子何时以及如何泛素化，并揭示泛素化调节转录因子活性的基本机制。最后，我们将通过阐述蛋白酶体在基因控制中所起的作用来建立我们对转录因子泛素化的分析。这些研究的结果将为转录和泛素-蛋白酶体途径如何相互作用提供有价值的见解，并将为我们理解转录调控的这一新维度提供一个范例。

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.