title: Oxidized nucleotide insertion by pol β confounds ligation during base excision repair.
abstract: Oxidative stress in cells can lead to accumulation of reactive oxygen species and oxidation of DNA precursors. Oxidized purine nucleotides can be inserted into DNA during replication and repair. The main pathway for correcting oxidized bases in DNA is base excision repair (BER), and in vertebrates DNA polymerase β (pol β) provides gap filling and tailoring functions. Here we report that the DNA ligation step of BER is compromised after pol β insertion of oxidized purine nucleotides into the BER intermediate in vitro. These results suggest the possibility that BER mediated toxic strand breaks are produced in cells under oxidative stress conditions. We observe enhanced cytotoxicity in oxidizing-agent treated pol β expressing mouse fibroblasts, suggesting formation of DNA strand breaks under these treatment conditions. Increased cytotoxicity following MTH1 knockout or treatment with MTH1 inhibitor suggests the oxidation of precursor nucleotides.
authors.affiliation: Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Melike
authors.initials: M
authors.lastname: Çağlayan
authors.affiliation: Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Julie K
authors.initials: JK
authors.lastname: Horton
authors.affiliation: Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Dai
authors.affiliation: Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Donna F
authors.initials: DF
authors.lastname: Stefanick
authors.affiliation: Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
mesh_terms: D000818:Animals; D001959:Bromates / Q000494:pharmacology; D002460:Cell Line; D000077547:Crizotinib; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D019951:DNA Polymerase beta / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects; D003848:Deoxyguanine Nucleotides / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D051379:Mice; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism
chemical_list: D001959:Bromates; D003848:Deoxyguanine Nucleotides; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011725:Pyridines; D034741:RNA, Small Interfering; C019536:potassium bromate; C078206:8-oxodeoxyguanosine triphosphate; D000077547:Crizotinib; D004247:DNA; D019951:DNA Polymerase beta; D010744:Phosphoric Monoester Hydrolases; C509779:Nudt1 protein, mouse