title: Inactivation of a common OGG1 variant by TNF-alpha in mammalian cells.
abstract: Reactive oxygen species threaten genomic integrity by inducing oxidative DNA damage. One common form of oxidative DNA damage is the mutagenic lesion 8-oxoguanine (8-oxodG). One driver of oxidative stress that can induce 8-oxodG is inflammation, which can be initiated by the cytokine tumor necrosis factor alpha (TNF-α). Oxidative DNA damage is primarily repaired by the base excision repair pathway, initiated by glycosylases targeting specific DNA lesions. 8-oxodG is excised by 8-oxoguanine glycosylase 1 (OGG1). A common Ogg1 allelic variant is S326C-Ogg1, prevalent in Asian and Caucasian populations. S326C-Ogg1 is associated with various forms of cancer, and is inactivated by oxidation. However, whether oxidative stress caused by inflammatory cytokines compromises OGG1 variant repair activity remains unknown. We addressed whether TNF-α causes oxidative stress that both induces DNA damage and inactivates S326C-OGG1 via cysteine 326 oxidation. In mouse embryonic fibroblasts, we found that S326C-OGG1 was inactivated only after exposure to H2O2 or TNF-α. Treatment with the antioxidant N-acetylcysteine prior to oxidative stress rescued S326C-OGG1 activity, demonstrated by in vitro and cellular repair assays. In contrast, S326C-OGG1 activity was unaffected by potassium bromate, which induces oxidative DNA damage without causing oxidative stress, and presumably cysteine oxidation. This study reveals that Cys326 is vulnerable to oxidation that inactivates S326C-OGG1. Physiologically relevant levels of TNF-α simultaneously induce 8-oxodG and inactivate S326C-OGG1. These results suggest a mechanism that could contribute to increased risk of cancer among S326C-Ogg1 homozygous individuals.
authors.affiliation: Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA; Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA, 30322, USA.
authors.forename: Jordan
authors.initials: J
authors.lastname: Morreall
authors.affiliation: Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA; Graduate Program in Cancer Biology, Emory University, Atlanta, GA, 30322, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Limpose
authors.affiliation: Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
authors.forename: Clayton
authors.initials: C
authors.lastname: Sheppard
authors.affiliation: Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
authors.forename: Yoke Wah
authors.initials: YW
authors.lastname: Kow
authors.affiliation: Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA.
authors.forename: Erica
authors.initials: E
authors.lastname: Werner
authors.affiliation: Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA; Emory Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA; Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, 30322, USA; Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, 30322, USA. Electronic address: medpwd@emory.edu.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Doetsch
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D045647:DNA Glycosylases / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics; D055785:Gene Knockdown Techniques; D020022:Genetic Predisposition to Disease; D006720:Homozygote; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D009369:Neoplasms / Q000235:genetics*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D020641:Polymorphism, Single Nucleotide; D017382:Reactive Oxygen Species / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human
keywords: 8-oxodG; Cys326-Ogg1; H(2)O(2); ROS; S326C-Ogg1; TNF-α