Polymorphic XRCC1 and Base Excision RepairEPA Grant Number: FP916426
Title: Polymorphic XRCC1 and Base Excision Repair
Investigators: Zipprich, Jennifer L.
Institution: Columbia University in the City of New York
EPA Project Officer: Manty, Dale
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $111,344
RFA: STAR Graduate Fellowships (2004) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Biochemistry, Molecular Biology, Cell Biology, Development Biology, and Genetics
DNA repair pathways help to safeguard the genomic integrity of the cell by resolving DNA damage efficiently and accurately. Unrepaired damage may result in mutation(s) in genes critical for regulating cell growth or maintenance, one of the possible outcomes of which is cancer. Potentially influential in the process of chemical exposure to disease onset is inherited genetic polymorphisms in genes encoding DNA repair proteins. These polymorphisms may confer subtle alterations in DNA repair capacity and/or accuracy thereby contributing to disease susceptibility. The objective of my research project is to focus on X-Ray Cross Complementing-1 (XRCC1), a DNA repair protein that has several polymorphic forms including R194W (arginine to tryptophan change at amino acid position 194), R280H (arginine to histidine change at amino acid position 280), and R399Q (arginine to glutamine change at amino acid position 399).
XRCC1 coordinates short patch base excision repair (BER) by interacting with other DNA repair proteins (e.g., DNA Polymerase β, DNA Ligase IIIα, and PARP-1) and is involved in the glycosylase, endonuclease, polymerase, and ligase steps of the repair process. Some cell phenotyping data and epidemiologic data suggest that polymorphic XRCC1 may alter DNA repair efficiency or accuracy, contributing to an increase in DNA damage and cancer risk, respectively. It is my intent to explore the molecular mechanisms related to BER that may be altered in the presence of polymorphic XRCC1 (R399Q, R280H, R194W) by using a combination of in vitro and cell phenotyping assays. Because XRCC1 acts as a coordinator of BER, our initial approach will be to evaluate the ability of polymorphic XRCC1 (R194W, R280H, R399Q) to bind with its BER partners (APE1, DNA polymerase B, and DNA Ligase III). Subsequently, we will use in vitro assays to investigate potential functional impacts in the form of altered DNA polymerase fidelity or decrements in repair efficiency in the presence of polymorphic forms of XRCC1. Finally, direct detection of 1,N 6-ethenodeoxyadenosine-DNA adducts by ELISA and mutational analysis by the HPRT assay and sequencing, will be used to evaluate repair efficiency and accuracy in lymphocytic cell lines that have been genotyped for XRCC1 polymorphisms. One benefit of this research may be its contribution to the growing consensus that individual variability in response to toxicant exposure is an important factor to consider when creating environmental or occupational standards to protect human health.