Son Daisuke, Kojima Ichiro, Inagi Reiko, Matsumoto Makiko, Fujita Toshiro, Nangaku Masaomi
Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Am J Physiol Renal Physiol. 2008 Jan;294(1):F62-72. doi: 10.1152/ajprenal.00113.2007. Epub 2007 Oct 24.
Accumulating evidence suggests a pathogenic role of chronic hypoxia in various kidney diseases. Chronic hypoxia in the kidney was induced by unilateral renal artery stenosis, followed 7 days later by observation of tubulointerstitial injury. Proteomic analysis of the hypoxic kidney found various altered proteins. Increased proteins included lipocortin-5, calgizzarin, ezrin, and transferrin, whereas the decreased proteins were alpha(2u)-globulin PGCL1, eukaryotic translation elongation factor 1alpha(2), and Cu/Zn superoxide dismutase (SOD1). Among these proteins, we focused on Cu/Zn-SOD, a crucial antioxidant. Western blot analysis and real-time quantitative PCR analysis confirmed the downregulation of Cu/Zn-SOD in the chronic hypoxic kidney. Furthermore, our laser capture microdissection system showed that the expression of Cu/Zn-SOD was predominant in the tubulointerstitium and was decreased by chronic hypoxia. The tubulointerstitial injury estimated by histology and immunohistochemical markers was ameliorated by tempol, a SOD mimetic. This amelioration was associated with a decrease in levels of the oxidative stress markers 4-hydroxyl-2-nonenal and nitrotyrosine. Our in vitro studies utilizing cultured tubular cells revealed a role of TNF-alpha in downregulation of Cu/Zn-SOD. Since the administration of anti-TNF-alpha antibody ameliorated Cu/Zn-SOD suppression, TNF-alpha seems to be one of the suppressants of Cu/Zn-SOD. In conclusion, our proteomic analysis revealed a decrease in Cu/Zn-SOD, at least partly by TNF-alpha, in the chronic hypoxic kidney. This study, for the first time, uncovered maladaptive suppression of Cu/Zn-SOD as a mediator of a vicious cycle of oxidative stress and subsequent renal injury induced by chronic hypoxia.
越来越多的证据表明慢性缺氧在各种肾脏疾病中具有致病作用。通过单侧肾动脉狭窄诱导肾脏慢性缺氧，7天后观察肾小管间质损伤。对缺氧肾脏进行蛋白质组学分析发现了多种改变的蛋白质。增加的蛋白质包括脂皮质素-5、钙结合蛋白、埃兹蛋白和转铁蛋白，而减少的蛋白质是α(2u)-球蛋白PGCL1、真核翻译延伸因子1α(2)和铜/锌超氧化物歧化酶（SOD1）。在这些蛋白质中，我们重点关注了关键抗氧化剂铜/锌超氧化物歧化酶。蛋白质印迹分析和实时定量PCR分析证实了慢性缺氧肾脏中铜/锌超氧化物歧化酶的下调。此外，我们的激光捕获显微切割系统显示铜/锌超氧化物歧化酶的表达在肾小管间质中占主导地位，并且因慢性缺氧而降低。通过组织学和免疫组化标记物评估的肾小管间质损伤通过超氧化物歧化酶模拟物tempol得到改善。这种改善与氧化应激标记物4-羟基-2-壬烯醛和硝基酪氨酸水平的降低有关。我们利用培养的肾小管细胞进行的体外研究揭示了肿瘤坏死因子-α在下调铜/锌超氧化物歧化酶中的作用。由于给予抗肿瘤坏死因子-α抗体可改善铜/锌超氧化物歧化酶的抑制作用，肿瘤坏死因子-α似乎是铜/锌超氧化物歧化酶的抑制剂之一。总之，我们的蛋白质组学分析揭示了慢性缺氧肾脏中铜/锌超氧化物歧化酶的减少，至少部分是由肿瘤坏死因子-α引起的。这项研究首次发现铜/锌超氧化物歧化酶的适应性抑制是慢性缺氧诱导的氧化应激恶性循环和随后肾损伤的介质。
