DNA Repair Gene OGG1 Ser326Cys Polymorphism and DNA Damage in Patients with Type 2 Diabetes

Abstract

8-hydroxydeoxyguanosine (8-OHdG) is the most frequent oxidative DNA damage. 8-oxo-deoxyguanosine DNA glycosylase 1 (OGG1) is involved in the repair of 8-OHdG. Many studies indicated that DNA repair is decreased in type 2 diabetes (T2DM). Single nucleotide polymorphisms in DNA repair genes may be linked to a decrease in DNA repair activity. The main objective of this study was to see how the OGG1 Ser326Cys gene polymorphism affected OGG1 expression and urinary excretion of 8-OHdG in T2DM patients. OGG1 expression and OGG1 genotyping in lymphocytes were detected by immunocytochemical staining and Polymerase Chain Reaction-Restriction Fragment Length Polymorphism assay, respectively. Urinary 8-OHdG levels were measured by using ELISA kit in patients with T2DM. Compared with control cases, patients with T2DM had lower OGG1 immunopositivity and higher urinary 8-OHdG levels. No significant difference was found in OGG1 immunopositivity or urinary 8-OHdG levels between subjects with different OGG1 genotypes in both groups. In conclusion, The OGG1 Ser326Cys gene polymorphism has no effect on neither OGG1 expression nor urinary 8-OHdG levels. Increased urinary 8-OHdG levels despite low OGG1 immunopositivity may be derived from the action of other DNA repair enzymes.