title: Repair of 8-oxoG is slower in endogenous nuclear genes than in mitochondrial DNA and is without strand bias.
abstract: DNA is vulnerable to the attack of certain oxygen radicals and one of the major DNA lesions formed is 7,8-dihydro-8-oxoguanine (8-oxoG), a highly mutagenic lesion that can mispair with adenine. The repair of 8-oxoG was studied by measuring the gene specific removal of 8-oxoG after treatment of Chinese hamster ovary (CHO) fibroblasts with the photosensitizer Ro19-8022. This compound introduces 8-oxoG lesions, which can then be detected with the Escherichia coli formamidopyrimidine DNA glycosylase (FPG). In this report we present gene specific repair analysis of endogenous genes situated in different important cellular regions and also the first analysis of strand specific DNA repair of 8-oxoG in an endogenous gene. We were not able to detect any preferential repair of transcribed genes compared to non-transcribed regions and we did not detect any strand-bias in the repair of the housekeeping gene, dihydrofolate reductase (DHFR). In vivo, mitochondrial DNA is highly exposed to reactive oxygen species (ROS), and we find that the repair of 8-oxoG is more efficient in the mitochondrial DNA than in the nuclear DNA.
authors.affiliation: Danish Center for Molecular Gerontology, Department of Molecular and Structural Biology, Aarhus University, Aarhus, Denmark.
authors.forename: Tina
authors.initials: T
authors.lastname: Thorslund
authors.forename: Morten
authors.initials: M
authors.lastname: Sunesen
authors.forename: Vilhelm A
authors.initials: VA
authors.lastname: Bohr
authors.forename: Tinna
authors.initials: T
authors.lastname: Stevnsner
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D016466:CHO Cells / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004260:DNA Repair; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D043382:DNA-Formamidopyrimidine Glycosylase; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D016296:Mutagenesis; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011759:Pyrrolidines / Q000494:pharmacology; D011807:Quinolizines / Q000494:pharmacology; D012313:RNA / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species
chemical_list: D004272:DNA, Mitochondrial; D004275:DNA, Ribosomal; D029968:Escherichia coli Proteins; D011759:Pyrrolidines; D011807:Quinolizines; D017382:Reactive Oxygen Species; C076809:Ro 19-8022; D012313:RNA; D000080242:8-Hydroxy-2'-Deoxyguanosine; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D003849:Deoxyguanosine