Study on oxidative DNA damage and repair enzyme in acute and chronic renal disease

Research Project

Project/Area Number	13671117
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Kidney internal medicine
Research Institution	Kyushu University
Principal Investigator	HIRAKATA Hideki Faculty of Medicine, Ass. Prof., 医学部附属病院, 助教授 (70181146)
Co-Investigator(Kenkyū-buntansha)	FUKUDA Kyoichi Faculty of Medicine, Assistant, 医学部附属病院, 助手 (90294925) KANAI Hidetoshi Faculty of Medicine, Assistant, 医学部附属病院, 助手 (20311839) NAKABEPPU Yusaku Medical Institute of Bioregulation, Prof., 生体防御医学研究所, 教授 (30180350)
Project Period (FY)	2001 – 2002
Project Status	Completed (Fiscal Year 2002)
Budget Amount *help	¥3,600,000 (Direct Cost: ¥3,600,000) Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000) Fiscal Year 2001: ¥1,800,000 (Direct Cost: ¥1,800,000)
Keywords	oxidative DNA damage / 8-oxoguanine / OGG1 / acute tubular necrosis / ischemia-reperfusion injury / cisplatin / necrosis / apoptosis / 8-オキソグアニン / 虚血再潜流傷害 / necrosis / apoptosis
Research Abstract	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 OGG1gene 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 1 h 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 6 h after I/R and preceded the necrosis of proximal tubular cells in the OM, An Rna … More se protection assy showed a high level of OGG1 mRNA in the normal kidney, and the level decreased within 3 h only in the OM, and increased thereafter 1 to 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 3 h 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. Furthermore, we examined the involvement of 8-oxo-dG in cisplatin-induced renal tubular cell death, in vivo and in vitro. Cisplatin induced accumulation of 8-oxo-dG in renal tubular cells before cell death, and co-administration of DMTU, a scavenger of hydroxyl radicals, inhibited such accumulation and renal tubular damage. In the kidney of 5/6 nephrectomized rats, obvious accumulation of 8-oxo-dG was not observed. Less