Repair of Endogenous DNA Damage Section
David M. Wilson III, Ph.D., Chief
The genetic material of aerobic organisms is susceptible to spontaneous decomposition and attack by oxygen radicals generated through normal cellular processes, such as mitochondrial respiration. Resulting modifications to the nuclear and mitochondrial genomes, which my group defines as endogenous DNA damage, includes a wide spectrum of base modifications, such as 8-oxoguanine, abasic sites and single-strand breaks (SSBs), as well as more complex damages, such as cyclopurines and DNA interstrand crosslinks (ICLs). If unrepaired, persistent DNA damage can drive mutagenic events or lead to senescence or cell death, outcomes that contribute to disease and aging. My laboratory aims to define the molecular mechanisms of repair pathways that cope with endogenous DNA damage, with an eye on ways in which these systems can be manipulated towards improved healthspan.
The base excision repair (BER) pathway is the major system for removing many forms of endogenous DNA damage. Apurinic/apyrimidinic endonuclease 1 (APE1) operates centrally in BER, primarily as an AP site incision enzyme, and participates in 3′-damage repair as well. In addition, APE1 has roles in transcriptional regulation independent of its DNA repair functions. Using knockout cell lines and mutant expression systems, we are elucidating the contribution of the putative functions of APE1 in viability and stress resistance, and assessing the involvement of APE1 population variants and BER defects in cellular transformation and senescence.
Like the brain, skeletal muscle exhibits a high oxidative load due to its high energy demands, leading to an elevated level of oxidative damage. X-ray cross-complementing protein 1 (XRCC1) is a non-enzymatic scaffold protein that coordinates the BER-associated pathway, SSB repair (SSBR), a mechanism that has been shown to be critically involved in preserving brain health. Using genetically-defined XRCC1 mouse and cell-based models, we are exploring the hypothesis that skeletal muscle is particularly susceptible to defects in the repair of oxidative DNA lesions.
Cockayne syndrome (CS) is a recessive disorder characterized by photosensitivity, growth retardation, neurological abnormalities and premature aging. We are pursuing the hypothesis that a component of CS involves a defect in the repair of transcription-blocking lesions, namely ICLs, and are currently elucidating the molecular details of a replication-independent, transcription-associated ICL repair process that engages the CS proteins. Our observation that patient missense mutants exhibit abnormal intracellular localization, most notably nucleolar exclusion, has also prompted us to explore the hypothesis that several CS clinical phenotypes arise from a defect in ribosomal DNA metabolism and consequent nucleolar stress.
- Oxidative DNA Damage
- Base Modification
- Abasic Site
- Single-Strand Break
- Interstrand Crosslink
- DNA Repair
- Base Excision Repair
- APE1, XRCC1
- Single-Strand Break Repair
- Transcription-Coupled Nucleotide Excision Repair
- Disease Susceptibility
- Premature Aging
- Neurological Dysfunction
- Cockayne Syndrome
Findings and Publications
Illuzzi, J.L., McNeill, D.R., Bastian, P., Brenerman, B., Wersto, R., Russel, H.R., Bunz, F., McKinnon, P.J., Becker, K.G., and Wilson III, D.M. Tumor-associated APE1 variant exhibits reduced complementation efficiency, but does not promote cancer cell phenotypes. Environ. Mol. Mutagen. 58:84-98, 2017
Scheibye-Knudsen, M., Tseng, A.H.-H., Jensen, M.B., Scheibye-Alsing, K., Fang, E.F., Iyama, T., Bharti, S.K., Marosi, K., Froetscher, L., Kassahun, H., Eckley, D.M., Maul, R., Bastian, P., De, S., Ghosh, S., Nilsen, H., Goldberg, I., Mattson, M.P., Wilson III, D.M., Brosh Jr., R.M., Gorospe, M., and Bohr, V.A. CSA and CSB converge on transcription-linked resolution of non-B DNA. Proc. Natl. Acad. Sci. USA 113:12502-12507, 2016
Iyama, T., Lee, S.Y., Berquist, B.R., Gileadi, O., Bohr, V.A., Seidman, M.M., McHugh, P.J., and Wilson III, D.M. CSB interacts with SNM1A and promotes DNA interstrand crosslink processing. Nucleic Acids Res. 43:247-258, 2015
Brenerman, B.M., Illuzzi, J.L., and Wilson III, D.M. Base excision repair capacity in informing healthspan. Carcinogenesis. 35:2643-2652, 2014
Sykora, P., Croteau, D.L., Bohr, V.A., and Wilson III, D.M. Aprataxin localizes to mitochondria and preserves mitochondrial function. Proc. Natl. Acad. Sci. USA 108:7437-7442, 2011