Kitada Munehiro, Koya Daisuke, Sugimoto Toshiro, Isono Motohide, Araki Shin-ichi, Kashiwagi Atsunori, Haneda Masakazu
Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan.
Diabetes. 2003 Oct;52(10):2603-14. doi: 10.2337/diabetes.52.10.2603.
Oxidative stress is implicated to play an important role in the development of diabetic vascular complications, including diabetic nephropathy. It is unclear whether oxidative stress is primarily enhanced in the diabetic glomeruli or whether it is merely a consequence of diabetes-induced glomerular injury. To address this issue, we examined diabetic glomeruli to determine whether oxidative stress is enhanced, as well as examined the role of protein kinase C (PKC)-beta activation in modulating NADPH oxidase activity. Urinary 8-hydroxydeoxyguanosine excretion and its intense immune-reactive staining in the glomeruli were markedly higher in diabetic than in control rats, and these alterations were ameliorated by a treatment with a selective PKC-beta inhibitor, ruboxistaurin (RBX; LY333531) mesylate, without affecting glycemia. NADPH oxidase activity, which was significantly enhanced in diabetic glomeruli and the source of reactive oxygen species (ROS) generation, was also improved by RBX treatment by preventing the membranous translocation of p47phox and p67phox from cytoplasmic fraction without affecting their protein levels. Adenoviral-mediated PKC-beta(2) overexpression enhanced ROS generation by modulating the membranous translocation of p47phox and p67phox in cultured mesangial cells. We now demonstrate that oxidative stress is primarily enhanced in the diabetic glomeruli due to a PKC-beta-dependent activation of NADPH oxidase resulting in ROS generation.
氧化应激被认为在糖尿病血管并发症（包括糖尿病肾病）的发展中起重要作用。目前尚不清楚氧化应激是主要在糖尿病肾小球中增强，还是仅仅是糖尿病诱导的肾小球损伤的结果。为了解决这个问题，我们检查了糖尿病肾小球以确定氧化应激是否增强，并研究了蛋白激酶C（PKC）-β激活在调节NADPH氧化酶活性中的作用。糖尿病大鼠尿中8-羟基脱氧鸟苷排泄及其在肾小球中的强烈免疫反应性染色明显高于对照大鼠，用选择性PKC-β抑制剂甲磺酸鲁伯斯塔林（RBX；LY333531）治疗可改善这些改变，且不影响血糖水平。NADPH氧化酶活性在糖尿病肾小球中显著增强，是活性氧（ROS）产生的来源，RBX治疗通过阻止p47phox和p67phox从细胞质部分向膜的转位而不影响其蛋白水平，也改善了NADPH氧化酶活性。腺病毒介导的PKC-β(2)过表达通过调节培养的系膜细胞中p47phox和p67phox的膜转位增强了ROS的产生。我们现在证明，由于PKC-β依赖的NADPH氧化酶激活导致ROS产生，氧化应激在糖尿病肾小球中主要增强。
