RNA-mediated genome instability : elucidating novel contributions to R-loop-dependent DNA damage
Abstract/Contents
- Abstract
- R-loops are co-transcriptional structures that form when the nascent RNA hybridizes to the complementary DNA. While R-loops serve a variety of physiological functions in regulating key cellular processes, R-loop formation has also been shown to cause DNA damage and genome instability. Specifically, loss of RNA processing and R-loop modulating factors has been shown to cause an increase in DNA damage and hyper-recombination that are R-loop dependent. The processes that contribute to R-loop formation and the mechanisms that contribute to R-loop induced DNA damage are not fully understood. In this thesis, we first examine a novel mechanism by which R-loops are processed into DNA damage. We then interrogate how changes in transcription alter R-loop levels and explore the consequences of changes in R-loop levels on DNA damage formation. In Chapter 2, we demonstrate in human cells that R-loops induced by loss of RNA processing factors, including the RNA/DNA helicases Aquarius (AQR) and Senataxin (SETX), or by the inhibition of topoisomerase I, are processed into DSBs by the nucleotide excision repair (NER) endonucleases XPF and XPG. We find that the processing of R-loops into DSBs requires the transcription-coupled NER (TC-NER) factor CSB but occurs independently of global genome repair. These findings suggest that TC-NER factors play a role in generating R-loop-induced DNA damage and genome instability. The hormone estrogen (E2) binds the estrogen receptor to promote transcription of E2-responsive genes in the breast and other tissues. E2 also has links to genomic instability and elevated E2 levels are tied to breast cancer. In Chapter 3, we show that E2 stimulation causes a rapid and global increase in the formation of R-loops. We show that E2-dependent R-loop formation is highly enriched at E2-responsive genomic loci and that E2 induces DNA replication-dependent double-strand breaks (DSBs). Strikingly, many of the DSBs that accumulate in response to E2 are R-loop dependent. Thus, R-loops resulting from the E2 transcriptional response are a significant source of DNA damage. This work reveals a novel mechanism by which E2 stimulation leads to genomic instability and highlights how transcriptional programs play an important role in shaping the genomic landscape of DNA damage susceptibility. Taken together, these findings offer insight into the role of elevated transcription and RNA processing factors in R-loop formation and demonstrate a novel mechanism by which R-loops are processed into DNA damage.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Stork, Caroline Townsend |
|---|---|
| Associated with | Stanford University, Department of Biology. |
| Primary advisor | Cimprich, Karlene |
| Thesis advisor | Cimprich, Karlene |
| Thesis advisor | Gozani, Or Pinchas |
| Thesis advisor | Stearns, Tim |
| Thesis advisor | Wysocka, Joanna, Ph. D |
| Advisor | Gozani, Or Pinchas |
| Advisor | Stearns, Tim |
| Advisor | Wysocka, Joanna, Ph. D |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Caroline Townsend Stork. |
|---|---|
| Note | Submitted to the Department of Biology. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Caroline Townsend Stork
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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