ERCC1-XPF is a mammalian structure specific endonuclease that incises at the junction of double and 3 single-stranded DNA. ERCC1-XPF and its homologs are implicated in multiple DNA repair pathways including, nucleotide excision repair, interstrand crosslink repair, double strand break repair, repair of AP sites, and telomere maintenance, making it essential for viability. The pleiotropic phenotypes of ERCC1-XPF deficiency in humans, range from the cancer-predisposition syndrome xeroderma pigmentosum to the XPF-ERCC1 progeroid syndrome, a disease of accelerated aging.
This document concentrates on dissecting the role of ERCC1-XPF in crosslink repair, elucidating the mechanisms underlying the dramatic phenotypic differences in patients with inherited XPF mutations, and exploring the utility of ERCC1 and XPF as biomarkers of tumor prognosis.
Ercc1 and Xpf knockout mice are phenocopies, illustrating that the two proteins function exclusively as a heterodimer. These models present a progeroid phenotype, reflected in some patients with XPF or ERCC1 mutations. We hypothesize that this accelerated aging is consequent on a failure to repair crosslinks, which are highly cytotoxic DNA lesions. The crosslink repair mechanism in animals remains poorly elucidated and the exact relationship of ERCC1-XPF to other players in this pathway, largely unexplored. Herein we show that ERCC1-XPF functions in the same pathway of crosslink repair as the Fanconi anemia proteins and that crosslink unhooking by ERCC1-XPF is required for the efficient binding of FANCD2 to the chromatin.
The pleiotropy of phenotypes associated with human ERCC1-XPF deficiency is puzzling. Often, the severity of phenotype does not correlate with the DNA incising ability of the mutant proteins. We show here that the phenotypic heterogeneity is at least partially explained by the mislocalization of mutant proteins to the cytoplasm.
The public health importance of this work comes from the increasing interest in the regulation of ERCC1-XPF expression and activity, due to its involvement in DNA repair pathways implicated in the resistance of tumors to platinum-based chemotherapy. A panel of antibodies was tested extensively and optimized for use in clinical measurement of ERCC1-XPF. This will facilitate improved measurement of DNA repair proteins in clinical specimens and greater understanding of the mechanisms of tumor resistance to genotoxic therapy.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-12042009-164303 |
| Date | 27 January 2010 |
| Creators | Bhagwat, Nikhil |
| Contributors | Patricia Opresko, Susanne Gollin, Robert E. Ferrell, Laura J. Niedernhofer |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-12042009-164303/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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