Differential ability of polymorphic OGG1 proteins to suppress mutagenesis induced by 8-hydroxyguanine in human cell in vivo.

摘要: OGG1 protein has an ability to suppress mutagenesisinduced by 8-hydroxyguanine (8OHG), oxidativelydamaged promutagenic base. Here, the mutation sup-pressive was compared between two commonpolymorphic proteins, OGG1-Ser326 and OGG1-Cys326, using a supF forward assay employing an8OHG-containing plasmid. Polymorphic proteinswere exogenously expressed adenoviral transduction inH1299 human lung cancer cells, in which endogenousOGG1 undetectable western blot analysis.Mutations 8OHG were more efficiently suppressed inOGG1-Ser326 transduced cells than OGG1-Cys326 trans-duced cells. The results indicated that hasa lower prevent mutagenesis thanOGG1-Ser326 vivo cells; supporting theresults of recent association studies isa risk allele for several types cancers.IntroductionGenetic polymorphisms DNA repair genes have been con-sidered be genetic factors underlying causinginter-individual differences capacity muta-genesis damages (1). gene encodes aprotein with glycosylase AP lyase activities thatremoves oxidatively damagedpromutagenic base, from double-stranded vitro (2,3).We recently showed suppresses G:C toT:A transversions caused vivo(4,5). Ogg1 null mice higher contents andhigher rates T:A mutations their wild-type mice, predisposed adenocarcinoma andadenoma (6-- 8). These indicate geneplays key role preventing carcinogenesis sup-pressing 8OHG.A non-synonymous (associated amino acid change)genetic polymorphism at codon 326, Ser326Cys, wedefined previously (9), is strong candidateas factor based on followingfindings. Case-control (association) conducted usand others OGG1gene, varietyof cancers such as cancer, esophageal cancer,prostate orolaryngeal nasopharyngeal can-cer (10-- 12; reviewed ref. 1). Consistent thesereports, case control study, mean activityin extracts peripheral blood mononuclear inlung patients shown being significantly lowerthan activity participants (13). Differentialmutation suppressive suggested theOGG1-Ser326 although thispolymorphic located outside domains con-served among glycosylases. proteinwas OGG1-Ser326protein spontaneous Escherichiacoli (mutM mutY) strain defective (9).OGG1-Cys326 protein, purified bac-terial slightly glycosylaseactivity (14). Thus, it beenpredicted confers suscept-ibility due its encoding alower protein. However, mutationsuppressive against examined onlyfor but not OGG1-Cys326protein (4,5), thus, functional difference thetwo polymorphic proteins stillremained unclear. Therefore, this abilityagainst 8OHG-induced wascompared proteinsin vivo. For purpose, we undertook asupF shuttle plasmid,pMY189-8OHG, containing single residue (4).pMY189-8OHG transfected into H1299 endogeneous notdetectable analysis (4). Various amounts ofeach H1299cells through vectors infecting viruses severalMOIs (multiplicity infection). fre-quency site estimated quantitativereal-time PCR (QRT-PCR) method so frequen-cies large number samples could assessed rapidly andaccurately. pro-tein vivo.Materials methods