Much of our effort has been to define the structure-function mechanisms and biochemical properties of Ape1, the major protein for repairing abasic sites and certain 3-damages in DNA. Our work has revealed that Ape1 cleaves at AP sites in single-stranded regions of complex, biologically-relevant DNA structures, such as bubble and fork intermediates. These findings expand the known repertoire of substrates processed by this enzyme, and suggest novel functions for Ape1 likely coupled to transcription and/or replication. We recently found that the protein defective in the human segmental progeroid, Cockayne Syndrome B (CSB), physically and functionally interacts with Ape1. We are now determining the precise molecular contributions of CSB to BER and testing more exhaustively for possible helicase- and remodeling-type activities for CSB on a variety of DNA and RNA substrates. These studies in total will determine the molecular functions of CSB and how certain activities contribute to the associated disease manifestation. Last, we are designing methods to strategically regulate Ape1 repair activity using a dominant-negative approach in the hopes of developing more effective anti-cancer treatment paradigms.? ? In addition to the investigations above, we are elucidating the biochemical and cellular contributions of XRCC1, a major SSB repair (SSBR) factor. This protein functions primarily as a scaffold component, orchestrating specific protein-protein interactions required for efficient DNA repair. Our studies (i) suggest a link of XRCC1 to replication via an interaction with PCNA, (ii) argue against a role for XRCC1 in the early steps of BER, and (iii) indicate a biologically-relevant role for its interaction with DNA polymerase beta and in the subsequent repair step, nick ligation. Recent work has identified associations of XRCC1 with proteins defective in human neurodegenerative disorders AOA1 (Aprataxin) and SCAN1 (TDP1). We are assessing the role of XRCC1 in non-dividing (neuronal) cells and age-related pathologies (namely neurodegeneration) using cell culture models and heterozygous mice. The contributions of XRCC1 to DNA damage responses, chromosome stability, and telomere maintenance are concurrently being evaluated in dividing human cells using chronic RNAi knockdown strategies. The ongoing investigations will delineate the contribution of SSBs (i.e. an XRCC1 deficiency), a common DNA intermediate, to cancer promotion (genetic stability) and neurodegenerative disease (neuronal cell viability).

National Institute of Health (NIH)
National Institute on Aging (NIA)
Intramural Research (Z01)
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National Institute on Aging
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Wyatt, M D; Wilson 3rd, D M (2009) Participation of DNA repair in the response to 5-fluorouracil. Cell Mol Life Sci 66:788-99
Wilson 3rd, David M; Bohr, Vilhelm A; McKinnon, Peter J (2008) DNA damage, DNA repair, ageing and age-related disease. Mech Ageing Dev 129:349-52
Wilson 3rd, David M (2007) Processing of nonconventional DNA strand break ends. Environ Mol Mutagen 48:772-82
McNeill, Daniel R; Wilson 3rd, David M (2007) A dominant-negative form of the major human abasic endonuclease enhances cellular sensitivity to laboratory and clinical DNA-damaging agents. Mol Cancer Res 5:61-70
Wilson 3rd, David M; Thompson, Larry H (2007) Molecular mechanisms of sister-chromatid exchange. Mutat Res 616:11-23
Fan, Jinshui; Wilson, Paul F; Wong, Heng-Kuan et al. (2007) XRCC1 down-regulation in human cells leads to DNA-damaging agent hypersensitivity, elevated sister chromatid exchange, and reduced survival of BRCA2 mutant cells. Environ Mol Mutagen 48:491-500
Wilson 3rd, D M; McNeill, D R (2007) Base excision repair and the central nervous system. Neuroscience 145:1187-200
Wilson 3rd, David M; Bohr, Vilhelm A (2007) The mechanics of base excision repair, and its relationship to aging and disease. DNA Repair (Amst) 6:544-59
Harrigan, Jeanine A; Fan, Jinshui; Momand, Jamil et al. (2007) WRN exonuclease activity is blocked by DNA termini harboring 3'obstructive groups. Mech Ageing Dev 128:259-66
McNeill, Daniel R; Wong, Heng-Kuan; Narayana, Avinash et al. (2007) Lead promotes abasic site accumulation and co-mutagenesis in mammalian cells by inhibiting the major abasic endonuclease Ape1. Mol Carcinog 46:91-9

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