Effect of Nucleotide Excision Repair on Methylglyoxal-Induced DNA Damage

Methylglyoxal (MG) is an endogenous mutagen, formed nonenzymatically from triose phosphates during glycolysis in eukaryotic cells. MG reacts with amino groups in proteins and DNA, forming advanced glycation end-products (AGE). The major MG-derived AGE of DNA is N2-(1-carboxyethyl)-2??-deoxyguanosine (CEdG). CEdG is much more likely than dG to form non-Watson Crick base pairs, leading to elevated mutation and cancer. The biochemistry of MG-induced DNA damage, as well as the relevant repair pathway, is currently not well understood. In this project, the effect of nucleotide excision repair (NER) on MG-induced mutation is assessed using a forward mutation assay. NER-deficient (XP-G) and NER-proficient cells (XP-G+) were transfected with MG-treated pSP189 shuttle vector; mutation frequencies were determined in the supF target gene. Treatment of DNA with 12mM of MG results in a 4-fold induction of mutation in XPG cells. This frequency is minimized in the XPG+ cells, suggesting a role of NER in the repair of MG-induced mutations