title: Accumulation of 8-oxoguanine in the cellular DNA and the alteration of the OGG1 expression during ischemia-reperfusion injury in the rat kidney.
abstract: During ischemia-reperfusion (I/R) injury in the rat kidney, apoptosis was observed in the distal tubules of the cortico-medullary region and outer medulla (OM) while severe necrosis was seen in the proximal straight tubules of the OM. The majority of these changes disappeared within 2 weeks. We examined the contents of 8-oxo-2'-deoxyguanosine (8-oxo-dG), which is a major type of oxidative damage in DNA, in the rat kidney during I/R injury, and also investigated the expression level of the OGG1 gene encoding the 8-oxoguanine DNA glycosylase. High-performance liquid chromatography with an MS/MS analysis of the nuclear DNA revealed an immediate accumulation of 8-oxo-dG in the nuclear DNA prepared from the cortex and OM of the kidney 1h after I/R, and an immunohistochemical analysis demonstrated the immediate accumulation of 8-oxo-dG in the nuclei of renal tubular cells both in the cortex and OM. A delayed increase of cytoplasmic staining with anti-8-oxo-dG was observed only in the cortico-medulla and OM, where the cytoplasmic staining in the proximal tubular cells is higher than in the distal tubular cells. The level of cytoplasmic staining representing 8-oxo-dG in mitochondrial DNA, peaked at 6h after I/R and preceded the necrosis of proximal tubular cells in the OM. An RNase protection assay showed a high level of OGG1 mRNA in the normal kidney, and the level decreased within 3h only in the OM, and increased thereafter 1-7 days of I/R both in the cortex and OM. In situ hybridization showed higher levels of OGG1 mRNA expression in the renal tubules in the OM than in the cortex of the normal kidney, which decreased rapidly within 3h of I/R. Thus, the accumulation of 8-oxo-dG in the mitochondrial DNA rather than in nuclear DNA is likely to be involved in the pathogenic responses such as necrosis of renal tubular cells during I/R injury of the kidney, together with an altered level of OGG1 expression.
authors.affiliation: Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tsuruya
authors.forename: Masato
authors.initials: M
authors.lastname: Furuichi
authors.forename: Yohei
authors.initials: Y
authors.lastname: Tominaga
authors.forename: Michiya
authors.initials: M
authors.lastname: Shinozaki
authors.forename: Masanori
authors.initials: M
authors.lastname: Tokumoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yoshimitsu
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Fukuda
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Kanai
authors.forename: Hideki
authors.initials: H
authors.lastname: Hirakata
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Iida
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Nakabeppu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D004247:DNA / Q000378:metabolism*; D043382:DNA-Formamidopyrimidine Glycosylase; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007679:Kidney Medulla / Q000473:pathology; D009699:N-Glycosyl Hydrolases / Q000096:biosynthesis / Q000235:genetics*; D051381:Rats; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology
chemical_list: C024829:8-hydroxyguanine; D006147:Guanine; D004247:DNA; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase