Caspase-dependent and -independent pathways for cadmium-induced apoptosis in cultured kidney proximal tubule cells
Caspase-dependent and -independent pathways for cadmium-induced apoptosis in cultured kidney proximal tubule cells
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DOI：
10.1152/ajprenal.00276.2005
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发表时间：
2006-10-01
影响因子：
4.2
通讯作者：
Thevenod, Frank
中科院分区：
文献类型：
--
作者：
Lee, Wing-Kee;Abouhamed, Marouan;Thevenod, Frank
微摩尔浓度的肾毒性金属镉在暴露3-6小时内诱导大鼠肾近端小管（PT）细胞凋亡。潜在的细胞死亡途径仍然不清楚。采用Hoechst 33342/溴化乙锭核染色和3-（4，5-二甲基-2-噻唑基）-2，5-二苯基-2H-溴化四氮唑（MTT）细胞死亡试验，10-50 μ M镉在6和24 h诱导来自PT S1节段的永生化大鼠肾细胞凋亡，但仅在24 h出现坏死。镉（10 - 50 μ M）也引起线粒体细胞色素c（cyt. c）通过免疫荧光成像和免疫印迹测量，在24小时，但不是在6小时，-和骨化诱导因子释放。Caspase-9和-3仅被10 μ M镉激活24小时，相应地，细胞凋亡在24小时时被各自的抑制剂（z-LEHD-fetamine，z-DEVD-fetamine; 10 μ g/ ml）显著减少，但在6小时时没有，不影响坏死。在6小时，10 μ M镉增加了钙激活蛋白酶钙蛋白酶的活性，但在24小时，钙蛋白酶抑制剂（ALLN，PD 150606; 10-30 μ M）阻断细胞凋亡10 μ M镉在3-6小时。然而，PD-150606还在24 h时减弱caspase-3活性和细胞凋亡，表明钙蛋白酶依赖性caspase活化。因此，镉诱导的PT细胞凋亡涉及到一个复杂的和敏感的相互作用的信号级联反应，涉及线粒体促凋亡因子，钙蛋白酶和半胱天冬酶，其激活也决定了镉浓度和镉暴露的持续时间。
The nephrotoxic metal cadmium at micromolar concentrations induces apoptosis of rat kidney proximal tubule (PT) cells within 3-6 h of exposure. The underlying cell death pathways remain poorly defined. Using Hoechst 33342/ ethidium bromide nuclear staining and 3-(4,5-dimethyl-2-thiazolyl)2,5-diphenyl-2H-tetrazolium bromide (MTT) cell death assays, 10-50 mu M cadmium induced apoptosis of immortalized rat kidney cells derived from the S1-segment of PT at 6 and 24 h, but necrosis at 24 h only. Cadmium (10 -50 mu M) also caused mitochondrial cytochrome c (cyt. c)- and apoptosis-inducing factor release at 24 h, but not at 6 h, as measured by immunofluorescence imaging and immunoblotting. Caspases-9 and -3 were activated only by 10 mu M cadmium for 24 h, and accordingly apoptosis was significantly reduced by the respective inhibitors (z-LEHD-fmk, z-DEVD-fmk; 10 mu g/ ml) at 24 h, but not at 6 h, without affecting necrosis. At 6 h, 10 mu M cadmium increased the activity of the calcium-activated protease calpain, but not at 24 h, and calpain inhibitors (ALLN, PD 150606; 10-30 mu M) blocked apoptosis by 10 mu M cadmium at 3-6 h. However, PD-150606 also attenuated caspase-3 activity and apoptosis at 24 h, suggesting calpain-dependent caspase activation. Thus cadmium-induced apoptosis of PT cells involves a complex and sensitive interplay of signaling cascades involving mitochondrial proapoptotic factors, calpains and caspases, whose activation is also determined by cadmium concentration and the duration of cadmium exposure.