Diabetes-induced mitochondrial dysfunction in the retina
Diabetes-induced mitochondrial dysfunction in the retina
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DOI：
10.1167/iovs.03-0353
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发表时间：
2003-12-01
影响因子：
4.4
通讯作者：
Abbas, SN
中科院分区：
文献类型：
--
作者：
Kowluru, RA;Abbas, SN
目的。糖尿病患者视网膜的氧化应激增加，抗氧化剂抑制caspase-3的激活和视网膜病变的发展。本研究旨在探讨糖尿病对大鼠视网膜及离体视网膜毛细血管细胞线粒体中细胞色素c释放及Bax易位的影响。从链脲佐菌素诱导的糖尿病大鼠视网膜和分离的视网膜内皮细胞和周细胞中制备线粒体和细胞质部分，这些细胞在5或20 mM葡萄糖培养基中在超氧化物歧化酶（SOD）或合成的SOD模拟物（MnTBAP）存在下孵育长达10天。Western blot检测细胞色素c向细胞质中的释放，凋亡前蛋白Bax向线粒体中的易位，caspase-3活性和ELISA检测细胞死亡情况。糖尿病持续8个月的大鼠细胞色素c释放到细胞质中，Bax释放到视网膜制备的线粒体中，这种现象在糖尿病持续2个月时没有观察到。分离的视网膜毛细血管细胞与20 mM葡萄糖孵育增加细胞质中细胞色素c和线粒体中的Bax含量。这些异常伴有细胞凋亡增加。SOD或其模拟物可抑制葡萄糖诱导的细胞色素c释放、Bax易位和细胞凋亡。糖尿病病程较长时，视网膜线粒体渗漏，毛细血管细胞凋亡；细胞色素c开始在细胞质中积累Bax进入线粒体。抑制超氧化物可抑制葡萄糖诱导的细胞色素c和Bax的释放，并抑制内皮细胞和周细胞的凋亡。确定视网膜毛细血管细胞凋亡的机制可能为抑制糖尿病视网膜病变的发展提供新的治疗方法。
PURPOSE. Oxidative stress is increased in the retina in diabetes, and antioxidants inhibit activation of caspase-3 and the development of retinopathy. The purpose of this study was to investigate the effect of diabetes on the release of cytochrome c from mitochondria and translocation of Bax into mitochondria in the rat retina and in the isolated retinal capillary cells.METHODS. Mitochondria and cytosol fractions were prepared from retina of rats with streptozotocin-induced diabetes and from the isolated retinal endothelial cells and pericytes incubated in 5 or 20 mM glucose medium for up to 10 days in the presence of superoxide dismutase (SOD) or a synthetic mimetic of SOD (MnTBAP). The release of cytochrome c into the cytosol and translocation of the proapoptotic protein Bax into the mitochondria were determined by the Western blot technique and cell death by caspase-3 activity and ELISA assay.RESULTS. Diabetes of 8 months' duration in rats increased the release of cytochrome c into the cytosol and Bax into the mitochondria prepared from the retina, and this phenomenon was not observed at 2 months of diabetes. Incubation of isolated retinal capillary cells with 20 mM glucose increased cytochrome c content in the cytosol and Bax in the mitochondria. and these abnormalities were accompanied by increased cell apoptosis. Inclusion of SOD or its mimetic inhibited glucose-induced release of cytochrome c, translocation of Bax, and apoptosis.CONCLUSIONS. Retinal mitochondria become leaky when the duration of diabetes is such that capillary cell apoptosis can be observed; cytochrome c starts to accumulate in the cytosol and Bax into the mitochondria. Inhibition of superoxides inhibits glucose-induced release of cytochrome c and Bax and inhibits apoptosis in both endothelial cells and pericytes. Identifying the mechanism by which retinal capillary cells undergo apoptosis may reveal novel therapies to inhibit the development of retinopathy in diabetes.