Transcription Control By The Ubiquitin-Proteasome System

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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.