title: Cellular accumulation of Cys326-OGG1 protein complexes under conditions of oxidative stress.
abstract: The common Ser326Cys polymorphism in the base excision repair protein 8-oxoguanine glycosylase 1 is associated with a reduced capacity to repair oxidative DNA damage particularly under conditions of intracellular oxidative stress and there is evidence that Cys326-OGG1 homozygous individuals have increased susceptibility to specific cancer types. Indirect biochemical studies have shown that reduced repair capacity is related to OGG1 redox modification and also possibly OGG1 dimer formation. In the current study we have used bimolecular fluorescence complementation to study for the first time a component of the base excision repair pathway and applied it to visualise accumulation of Cys326-OGG1 protein complexes in the native cellular environment. Fluorescence was observed both within and around the cell nucleus, was shown to be specific to cells expressing Cys326-OGG1 and only occurred in cells under conditions of cellular oxidative stress following depletion of intracellular glutathione levels by treatment with buthionine sulphoximine. Furthermore, OGG1 complex formation was inhibited by incubation of cells with the thiol reducing agents β-mercaptoethanol and dithiothreitol and the antioxidant dimethylsulfoxide indicating a causative role for oxidative stress in the formation of OGG1 cellular complexes. In conclusion, this study has provided for the first time evidence of redox sensitive Cys326-OGG1 protein accumulation in cells under conditions of intracellular oxidative stress that may be related to the previously reported reduced repair capacity of Cys326-OGG1 specifically under conditions of oxidative stress.
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: M P
authors.initials: MP
authors.lastname: Kaur
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: E J
authors.initials: EJ
authors.lastname: Guggenheim
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Pulisciano
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Akbar
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: R M
authors.initials: RM
authors.lastname: Kershaw
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom. Electronic address: N.Hodges@bham.ac.uk.
authors.forename: N J
authors.initials: NJ
authors.lastname: Hodges
mesh_terms: D019328:Buthionine Sulfoximine / Q000494:pharmacology; D045744:Cell Line, Tumor; D045647:DNA Glycosylases / Q000096:biosynthesis* / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D006801:Humans; D018384:Oxidative Stress / Q000235:genetics; D013050:Spectrometry, Fluorescence
chemical_list: D019328:Buthionine Sulfoximine; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human; D004121:Dimethyl Sulfoxide
keywords: BiFC visualisation; Dimer; OGG1; Oxidative stress