TY - JOUR
T1 - Biochemical identification of a hydroperoxide derivative of the free 8-oxo-7,8-dihydroguanine base
AU - Hajas, Gyorgy
AU - Bacsi, Attila
AU - Aguilerra-Aguirre, Leopoldo
AU - German, Peter
AU - Radak, Zsolt
AU - Sur, Sanjiv
AU - Hazra, Tapas K.
AU - Boldogh, Istvan
N1 - Funding Information:
We are grateful to Sankar Mitra for his scientific advice, intellectual input, discussions, and reading/editing of the manuscript. We thank Mardelle Susman, technical editor, for editing our manuscript. We thank Dr. Miral Dizdaroglu (Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA) for assessment of 8-oxoG base levels. This work was supported by Grants NIEHS RO1 ES018948 (I.B.), NIAID/AI062885-01 (I.B.), NIA/AG 021830 (I.B.), and TAMOP 4.2.1/B-09/1/KONV-2010-0007 from the European Union and the European Social Fund (A.B.).
PY - 2012/2/15
Y1 - 2012/2/15
N2 - 8-Oxo-7,8-dihydroguanine is one the most abundant base lesions in pro- and eukaryotic DNA. In mammalian cells, it is excised by the 8-oxoguanine DNA glycosylase (OGG1) during DNA base-excision repair, and the generated free 8-oxoG base is one of the DNA-derived biomarkers of oxidative stress in biological samples. The modification of 8-oxoG in the context of nucleoside and DNA has been the subject of many studies; however, the oxidative transformation of the free 8-oxoG base has not been described. By using biochemical and cell biological assays, we show that in the presence of molecular oxygen, the free 8-oxoG base transforms to a highly reactive hydroperoxide (8-oxoG*). Specifically, 8-oxoG* oxidizes Amplex red to resorufin, H2DCF to DCF, Fe2+ to Fe3+, and GSH to GSSG. This property of 8-oxoG* was diminished by treatment with catalase and glutathione peroxidase, but not superoxide dismutase. 8-OxoG* formation was prevented by reducing agents or nitrogen atmosphere. Its addition to CM-H 2DCF-DA-loaded cells rapidly increased intracellular DCF fluorescence. There were no such properties observed for 8-oxodeoxyguanosine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 2′-deoxyguanosine, guanine, adenine, guanosine, and 8-hydroxyadenine. These data imply that a free 8-oxoG base is more susceptible to oxidation than is its nucleoside form and, consequently, it stands as unique among intact and oxidatively modified purines.
AB - 8-Oxo-7,8-dihydroguanine is one the most abundant base lesions in pro- and eukaryotic DNA. In mammalian cells, it is excised by the 8-oxoguanine DNA glycosylase (OGG1) during DNA base-excision repair, and the generated free 8-oxoG base is one of the DNA-derived biomarkers of oxidative stress in biological samples. The modification of 8-oxoG in the context of nucleoside and DNA has been the subject of many studies; however, the oxidative transformation of the free 8-oxoG base has not been described. By using biochemical and cell biological assays, we show that in the presence of molecular oxygen, the free 8-oxoG base transforms to a highly reactive hydroperoxide (8-oxoG*). Specifically, 8-oxoG* oxidizes Amplex red to resorufin, H2DCF to DCF, Fe2+ to Fe3+, and GSH to GSSG. This property of 8-oxoG* was diminished by treatment with catalase and glutathione peroxidase, but not superoxide dismutase. 8-OxoG* formation was prevented by reducing agents or nitrogen atmosphere. Its addition to CM-H 2DCF-DA-loaded cells rapidly increased intracellular DCF fluorescence. There were no such properties observed for 8-oxodeoxyguanosine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 2′-deoxyguanosine, guanine, adenine, guanosine, and 8-hydroxyadenine. These data imply that a free 8-oxoG base is more susceptible to oxidation than is its nucleoside form and, consequently, it stands as unique among intact and oxidatively modified purines.
KW - Free 8-oxoguanine base
KW - Free radicals
KW - Oxidative stress
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U2 - 10.1016/j.freeradbiomed.2011.11.015
DO - 10.1016/j.freeradbiomed.2011.11.015
M3 - Article
C2 - 22198182
AN - SCOPUS:84856224029
VL - 52
SP - 749
EP - 756
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
SN - 0891-5849
IS - 4
ER -