REGULATORY MECHANISMS OF TRANSCRIPTION AND ASSOCIATED DNA REPAIR

Author

Shivani Malik, Southern Illinois University CarbondaleFollow

Date of Award

12-1-2012

Degree Name

Doctor of Philosophy

Department

Molecular Biology, Microbiology and Biochemistry

First Advisor

Bhaumik, Sukesh

Abstract

Transcription is a crucial regulatory step in gene regulation modulated by several proteins. Any misregulation during transcription can lead to many diseases including cancer, neurodegenerative disorders and aging making it imperative to have a detailed mechanistic view of the process. Over the recent years, 26S proteasome has been implicated in transcriptional regulation through its proteolytic and non-proteolytic activities. While, the proteolytic role of proteasome in transcription has been extensively studied, its non-proteolytic function is poorly understood. Thus, one of my thesis aims had been to analyze the non-proteolytic role of proteasome in transcription. My results have revealed the non-proteolytic role of 26S proteasome in establishing a specific protein interaction network at the promoter for stimulated transcriptional initiation in vivo . In addition to its roles in transcription, 26S proteasome also plays an important role in the degradation of RNA polymerase II stalled at DNA lesion facilitating the rapid repair of transcriptionally active genes through a process of transcription coupled repair (TCR). My studies have addressed the key question of the fate of RNA polymerase II stalled at a lesion. My findings show that RNA polymerase II interacts with an elongation and TCR-specific factor, Rad26p. Upon encountering a lesion, RNA polymerase II stalls and unloads Rad26p on the site of DNA damage. Subsequently, the elongating RNA polymerase II is disassembled through the degradation of its largest subunit, Rpb1p. Further; our studies have also uncovered a novel role of Rad26p in chromatin disassembly, which facilitates transcriptional elongation and hence TCR. This work provides valuable insights into interplay of chromatin structure, transcriptional elongation and TCR. Finally, extending the regulatory knowledge of sense transcriptional initiation to antisense, my work has revealed the extensive participation of GTFs in the process. Collectively, results of above studies provide a comprehensive view of transcription and associated process of active genome repair.