Cd2+-induced cytochrome c release in apoptotic proximal tubule cells:: role of mitochondrial permeability transition pore and Ca2+ uniporter
Cd2+-induced cytochrome c release in apoptotic proximal tubule cells:: role of mitochondrial permeability transition pore and Ca2+ uniporter
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DOI：
10.1152/ajprenal.00224.2004
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发表时间：
2005-01-01
影响因子：
4.2
通讯作者：
Thévenod, F
中科院分区：
文献类型：
--
作者：
Lee, WK;Bork, U;Thévenod, F
镉可诱导肾近曲小管（PT）细胞凋亡。线粒体通过释放细胞色素c在毒性化合物诱导的细胞凋亡中起关键作用。我们的目的是探讨镉诱导大鼠PT细胞线粒体细胞色素c释放的机制。采用Hoechst 33342或MTT法，10 μ M Cd 2+在6和24 h诱导PT细胞凋亡，凋亡率为5 - 10%，仅在24 h与细胞色素c和凋亡诱导因子释放相关。这与先前描述的最大细胞内Cd 2+浓度在24小时，表明升高的Cd 2+可能直接诱导线粒体释放促凋亡因子。事实上，Cd 2+引起肿胀的能量隔离肾皮质线粒体（EC 50类似于9 μ M）和细胞色素c的释放，这是独立的渗透性转换孔（PTP）开放，因为PTP抑制剂环孢菌素A或bongkrekic酸没有效果。相反，Cd ~（2+）抑制PTP开放剂（PO_（43-）或H_2 O_2 + Ca ~（2+））诱导的细胞肿胀和细胞色素c释放。线粒体Ca 2+单向转运体（MCU）在线粒体损伤中起关键作用：1）MCU抑制剂（La 3+、钌红、Ru 360）防止肿胀和细胞色素c释放; 2）钌红减弱Cd 2+对PO 43-诱导的肿胀的抑制。利用Cd ~（2+）敏感的荧光指示剂FluoZin-1，Cd ~（2+）也被有丝分裂体吸收。水通道蛋白抑制剂AgNO 3可抑制Cd ~（2+）诱导的线粒体肿胀。这可能是部分介导的激活线粒体富集的水通道水通道蛋白-8。因此，胞液中的Cd 2+浓度超过一定的阈值，可能会直接导致线粒体损伤和凋亡的发展，通过相互作用与MCU和水通道的线粒体内膜。
Cd2+ induces apoptosis of kidney proximal tubule (PT) cells. Mitochondria play a pivotal role in toxic compound-induced apoptosis by releasing cytochrome c. Our objective was to investigate the mechanisms underlying Cd2+-induced cytochrome c release from mitochondria in rat PT cells. Using Hoechst 33342 or MTT assay, 10 muM Cd2+ induced similar to 5 - 10% apoptosis in PT cells at 6 and 24 h, which was associated with cytochrome c and apoptosis-inducing factor release at 24 h only. This correlated with previously described maximal intracellular Cd2+ concentrations at 24 h, suggesting that elevated Cd2+ may directly induce mitochondrial liberation of proapoptotic factors. Indeed, Cd2+ caused swelling of energized isolated kidney cortex mitochondria (EC50 similar to 9 muM) and cytochrome c release, which were independent of permeability transition pore (PTP) opening since PTP inhibitors cyclosporin A or bongkrekic acid had no effect. On the contrary, Cd2+ inhibited swelling and cytochrome c release induced by PTP openers (PO43- or H2O2 + Ca2+). The mitochondrial Ca2+ uniporter (MCU) played a key role in mitochondrial damage: 1) MCU inhibitors ( La3+, ruthenium red, Ru360) prevented swelling and cytochrome c release; and 2) ruthenium red attenuated Cd2+ inhibition of PO43--induced swelling. Using the Cd2+-sensitive fluorescent indicator FluoZin-1, Cd2+ was also taken up by mitoplasts. The aquaporin inhibitor AgNO3 abolished Cd2+-induced swelling of mitoplasts. This could be partially mediated by activation of the mitoplast-enriched water channel aquaporin-8. Thus cytosolic Cd2+ concentrations exceeding a certain threshold may directly cause mitochondrial damage and apoptotic development by interacting with MCU and water channels in the inner mitochondrial membrane.