Mitochondria are the major targets in albumin-induced apoptosis in proximal tubule cells
Mitochondria are the major targets in albumin-induced apoptosis in proximal tubule cells
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DOI：
10.1681/asn.2006040407
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发表时间：
2007-04-01
影响因子：
13.6
通讯作者：
Schwartz, George J.
中科院分区：
文献类型：
--
作者：
Erkan, Elif;Devarajan, Prasad;Schwartz, George J.
肾范围蛋白尿被认为是一个预后不良的因素。肾小管间质损伤和蛋白尿程度之间的相关性已得到很好的证实。为了解释晚期肾小球肾炎患者中观察到的肾小管萎缩，本研究探讨了暴露于无内毒素白蛋白（5、10和20 mg/ml）的培养人近端小管细胞（HKC-8）的凋亡机制。通过Hoechst 33342、膜联蛋白染色和半胱天冬酶3、8和9测定检测细胞凋亡。白蛋白的凋亡作用在10 mg/ml白蛋白时最大，并且在与20 mg/ml孵育的细胞中坏死占优势。在6小时开始观察到半胱天冬酶-9和-3活性增加，在16至24小时最大。促凋亡Bcl-2蛋白Bax在6 h时上调，与细胞色素C从线粒体易位到细胞质和线粒体膜电位的改变相关。活性氧（ROS）的产生在6 h显著，但在16和24 h下降。用ROS清除剂二甲基硫脲或抗氧化剂N-乙酰半胱氨酸处理不能减轻caspase-3的产生。泛蛋白激酶C抑制剂双吲哚马来酰亚胺-1保护细胞免于凋亡。结论：白蛋白通过刺激线粒体凋亡途径诱导人近曲小管细胞凋亡，而不依赖于ROS的产生。
Nephrotic-range proteinuria is considered a poor prognostic factor. A correlation between tubulointerstitial injury and the degree of proteinuria is well established. In an attempt to explain the tubular atrophy that is observed in advanced glomerulonephritides, this study investigated apoptotic mechanisms in cultured human proximal tubule cells (HKC-8) that were exposed to endotoxin-free albumin (5, 10, and 20 mg/ml). Apoptosis was detected by Hoechst 33342; annexin staining; and assays for caspases 3, 8, and 9. The apoptotic effect of albumin was maximal at 10 mg/ml albumin, and necrosis prevailed in cells that were incubated with 20 mg/ml. Increase in caspase-9 and -3 activity was observed starting at 6 and maximally at 16 to 24 h. The proapoptotic Bcl-2 protein Bax was upregulated at 6 h, associated with translocation of cytochrome-c from mitochondria to cytosol and alteration in the mitochondrial membrane potential. Production of reactive oxygen species (ROS) was significant at 6 h but declined at 16 and 24 h. Treatment with ROS scavenger dimethylthiourea or antioxidant N-acetylcysteine did not alleviate caspase-3 production. Pan protein kinase C inhibitor bisindolylmaleimide-1 protected the cells from apoptosis. It is concluded that albumin induces apoptosis in human proximal tubule cells by stimulating mitochondrial apoptotic pathway independent of ROS production.