Repair of Formamidopyrimidines in DNA Involves Different Glycosylases - Role of the OGG1, NTH1, and NEIL1 Enzymes

Published

December 9, 2005

Author(s)

J Hu, N de Souza-Pinto, K Haraguchi, Barbara A. Hogue, Pawel Jaruga, M M. Greenberg, Miral M. Dizdar, V. Bohr

Abstract

2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG) and 4,6-diamino-5-formamidopyrimidine (FapyA), are formed abundantly in DNA of cultured cells or tissues exposed to ionizing radiation or to other free radical-generating systems. We show here that FapyG levels in liver DNA from wild type mice are significantly higher than 8-hydroxyguanine (8-oxoG) levels. It is still unclear, however, how these lesions are metabolized in cells, largely due to previous unavailability of single-lesion synthetic oligonucleotide constructs. We recently reported the synthesis of oligonucleotides containing FapyG and FapyA at defined positions, and thus we present the first studies where repair of Fapy lesions is directly analyzed in nuclear and mitochondrial extracts from wild type and knockout mice lacking the two major DNA glycosylases for repair of oxidative DNA damage, OGG1 and NTH1. Both FapyG and FapyA were efficiently repaired in nuclear and mitochondrial extracts from wild type animals, but not in the glycosylase-deficient mice. Our results suggest that OGG1 is the major DNA glycosylase for the removal of FapyG and that NTH1 is the major glycosylase for removal of FapyA. Tissue specific analysis suggests that other DNA glycosylases may contribute to the repair of FapyA lesions when NTH1 is poorly expressed. We identified NEIL1 in liver mitochondria, which could account for the residual incision activity in the absence of OGG1 and NTH1. In accord with the lower incision activity, FapyG and FapyA levels were significantly elevated in DNA from the knockout mice, underscoring the biological role of OGG1 and NTH1 in the repair of these lesions.

Citation

Journal of Biological Chemistry

Volume

280

Issue

49

Pub Type

Journals

Keywords

DNA repair, DNA repair enzyme, formamidopyrimidines, GC/MS, Genomic instability, oxidative DNA damage

Citation

Hu, J. , de Souza-Pinto, N. , Haraguchi, K. , Hogue, B. , Jaruga, P. , Greenberg, M. , Dizdar, M. and Bohr, V. (2005), Repair of Formamidopyrimidines in DNA Involves Different Glycosylases - Role of the OGG1, NTH1, and NEIL1 Enzymes, Journal of Biological Chemistry (Accessed November 8, 2024)