Genetic inheritance, and resistance to age-related diseases such as cancer, depend on the stability of the human genome. Stable genome maintenance in turn depends critically on cellular systems that process """"""""spontaneous"""""""" DNA damage. Such damage includes hydrolytic decay lesions, in particular abasic sites, as well as lesions formed by metabolic by-products such as free radicals and alkylating agents. Existing data indicate that the base excision repair (BER) system is most likely to deal with this endogenous DNA damage. In BER, DNA glycosylases remove altered bases to generate abasic sites, which are further processed in several steps dependent on the Ape1 endonuclease and DNA polymerase beta. Our long-term goal has been to ascertain the biological functions of Ape1 protein as a central player in base excision repair (BER) of DNA and perhaps other processes, and to understand the coordination of activities in the various branches of BER. Past efforts have been valuable in defining the biochemistry of Ape1 activity, but only recently have we been able to conduct genetic tests of the protein's cellular function through the use of small-interfering RNA (siRNA). These data clearly support an essential role of Ape1 in maintaining the viability of human cells by processing abasic DNA damage formed by endogenous processes. Other recent work points to a novel role for the sirtuin Sirt6 in modulating BER, possibly through effects on the activity of DNA polymerase beta. Since deletion of the SIRT6 in mice shortens lifespan and generates various phenotypes associated with premature aging, these observations provide the first direct link between BER and the normal aging process. The work proposed here builds on this success in order to define the cellular function of Ape1 and the origins of the DNA damage that it processes, and how the BER can be modulated by a sirtuin.
Three specific aims will address our goals: 1. Establish human or mouse cell lines with regulated expression of APE1-specific si-RNA and examine the kinetics of the biological effects accompanying Ape1 depletion; 2. Determine the contribution of DNA glycosylases (in particular UNG2, OGG1, AAG/MPG, and NTH1) and of oxidative damage as sources of the lethal lesions that accumulate in Ape1-deficient cells; 3. Directly test the role of SirtG in DNA repair and the sub-pathways of BER.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM040000-17
Application #
7336328
Study Section
Molecular Genetics A Study Section (MGA)
Program Officer
Portnoy, Matthew
Project Start
1988-06-01
Project End
2010-12-31
Budget Start
2008-01-01
Budget End
2008-12-31
Support Year
17
Fiscal Year
2008
Total Cost
$336,200
Indirect Cost
Name
Harvard University
Department
Genetics
Type
Schools of Public Health
DUNS #
149617367
City
Boston
State
MA
Country
United States
Zip Code
02115
Quiñones, Jason L; Thapar, Upasna; Yu, Kefei et al. (2015) Enzyme mechanism-based, oxidative DNA-protein cross-links formed with DNA polymerase ? in vivo. Proc Natl Acad Sci U S A 112:8602-7
Madlener, Sibylle; Ströbel, Thomas; Vose, Sarah et al. (2013) Essential role for mammalian apurinic/apyrimidinic (AP) endonuclease Ape1/Ref-1 in telomere maintenance. Proc Natl Acad Sci U S A 110:17844-9
Fung, Hua; Demple, Bruce (2011) Distinct roles of Ape1 protein in the repair of DNA damage induced by ionizing radiation or bleomycin. J Biol Chem 286:4968-77
Liu, Pingfang; Demple, Bruce (2010) DNA repair in mammalian mitochondria: Much more than we thought? Environ Mol Mutagen 51:417-26
Auerbach, Paul A; Demple, Bruce (2010) Roles of Rev1, Pol zeta, Pol32 and Pol eta in the bypass of chromosomal abasic sites in Saccharomyces cerevisiae. Mutagenesis 25:63-9
Son, Mi-Young; Jun, Hyun-Ik; Lee, Kwang-Geun et al. (2009) Biochemical evaluation of genotoxic biomarkers for 2-deoxyribonolactone-mediated cross-link formation with histones. J Toxicol Environ Health A 72:1311-7
Zheng, Li; Zhou, Mian; Guo, Zhigang et al. (2008) Human DNA2 is a mitochondrial nuclease/helicase for efficient processing of DNA replication and repair intermediates. Mol Cell 32:325-36
Liu, Pingfang; Qian, Limin; Sung, Jung-Suk et al. (2008) Removal of oxidative DNA damage via FEN1-dependent long-patch base excision repair in human cell mitochondria. Mol Cell Biol 28:4975-87
Gellon, Lionel; Carson, Dena R; Carson, Jonathan P et al. (2008) Intrinsic 5'-deoxyribose-5-phosphate lyase activity in Saccharomyces cerevisiae Trf4 protein with a possible role in base excision DNA repair. DNA Repair (Amst) 7:187-98
Fung, Hua; Liu, Pingfang; Demple, Bruce (2007) ATF4-dependent oxidative induction of the DNA repair enzyme Ape1 counteracts arsenite cytotoxicity and suppresses arsenite-mediated mutagenesis. Mol Cell Biol 27:8834-47

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