DNA repair activity of 8-oxoguanine DNA glycosylase 1 (OGG1) in human lymphocytes is not dependent on genetic polymorphism Ser(326)/Cys(326)

8-Oxoguanine DNA glycosylase 1 (OGG1) is a DNA repair enzyme that excises 7 ,8-dihydro-8-oxoguanine (8oxoG) from DNA. Since 8oxoG is a highly mispairin g lesion, decreased OGG1 expression level could lead to a higher background mutation frequency and could possibly increase the cancer risk of an indiv idual under oxidative stress. In order to analyse the natural variation of OGG1, we measured the DNA repair activity in human lymphocytes of healthy i ndividuals by means of an 8oxoG-containing oligonucleotide assay. The data obtained revealed a two fold interindividual variation of OGG1 activity in lymphocytes. There was no difference in OGG1 activity due to gender and smo king behaviour. Transcriptional analyses of OGG1 showed the expression of t wo isoforms, la and b, in lymphocytes. Structural analysis of the human OGG 1 (hOGG1) gene revealed a Ser(326)/Cys(326) polymorphism in the Caucasian p opulation with allele frequencies of 75% for Ser(326) and 25% for Cys(326). This polymorphism was not associated with altered OGG1 activity. The descr ibed routine test system for measuring OGG1 activity in cryopreserved lymph ocytes provided highly reproducible results and is a useful tool for risk a ssessment associated with alterations in the repair of oxidative DNA damage . (C) 2001 Published by Elsevier Science B.V.