Shenker B J, Guo T L, O I, Shapiro I M
Departments of Pathology, School of Dental Medicine, Philadelphia, Pennsylvania 19104-6002, USA.
Toxicol Appl Pharmacol. 1999 May 15;157(1):23-35. doi: 10.1006/taap.1999.8652.
The objective of our study was to define the mechanism by which MeHgCl induces human T-cell apoptosis. We asked the question: does mercury disrupt the Deltapsim and induce a mitochondrial permeability transition state? Using two fluorescent reagents, JC-1 and DiOC6(3), we demonstrated that MeHgCl exposure resulted in a decrease in the Deltapsim. Since a decline in Deltapsim can disturb the pHi, we employed SNARF-1 to assess pHi; results indicate that mercury treatment reduced the pHi from 7.0 to 6.5. Consistent with these observations, we noted that uncoupled electron transfer reactions generated ROS, while cardiolipin, a mitochondrial phospholipid, was oxidized. In concert with the biochemical changes, there was a decrease in overall dimension of the mitochondria of mercury-treated cells and a loss in cristae architecture. The toxicant also depleted the thiol reserves of the cell and promoted translocation of cytochrome c from the mitochondria to the cytosol. Furthermore, when T cells were thiol-depleted, there was increased susceptibility to MeHgCl-induced apoptosis. Finally, we established a temporal relationship between the decline in Deltapsim, generation of ROS, and depletion of thiol reserves. The earliest detectable event was at the level of the mitochondrion; in the presence of MeHgCl there was a profound reduction in mitochondrial Deltapsim and a decline in GSH levels within 1 h. Subsequently, a further decrease in thiol reserves was linked to the generation of ROS. We propose that the target organelle for MeHgCl is the mitochondrion and that induction of oxidative stress leads to activation of death-signaling pathways.
我们研究的目的是确定氯化甲基汞诱导人T细胞凋亡的机制。我们提出了一个问题：汞是否会破坏线粒体膜电位（ΔΨm）并诱导线粒体通透性转换状态？使用两种荧光试剂JC-1和DiOC6(3)，我们证明了氯化甲基汞暴露导致线粒体膜电位降低。由于线粒体膜电位的下降会干扰细胞内pH值（pHi），我们使用SNARF-1来评估细胞内pH值；结果表明，汞处理使细胞内pH值从7.0降至6.5。与这些观察结果一致，我们注意到解偶联的电子传递反应产生活性氧（ROS），而线粒体磷脂心磷脂被氧化。与生化变化相一致，汞处理细胞的线粒体整体尺寸减小，嵴结构丧失。该毒物还耗尽了细胞的巯基储备，并促进细胞色素c从线粒体向细胞质的转位。此外，当T细胞的巯基被耗尽时，对氯化甲基汞诱导的凋亡的易感性增加。最后，我们建立了线粒体膜电位下降、活性氧生成和巯基储备耗尽之间的时间关系。最早可检测到的事件发生在线粒体水平；在氯化甲基汞存在的情况下，1小时内线粒体膜电位显著降低，谷胱甘肽（GSH）水平下降。随后，巯基储备的进一步减少与活性氧的生成有关。我们认为，氯化甲基汞的靶细胞器是线粒体，氧化应激的诱导导致死亡信号通路的激活。
