Almofti Mohamad Radwan, Ichikawa Tomokazu, Yamashita Kikuji, Terada Hiroshi, Shinohara Yasuo
Faculty of Pharmaceutical Sciences, The University of Tokushima, Shomachi 1, Tokushima 770-8505.
J Biochem. 2003 Jul;134(1):43-9. doi: 10.1093/jb/mvg111.
Various reagents are known to open the mitochondrial permeability pore (PTP) and induce a permeability transition (PT), releasing apoptogenic proteins from the intermembrane space and triggering apoptosis. In this study, we examined the effect of Ag(+), a known cytotoxic sulfhydryl-reactive heavy metal, on isolated rat liver mitochondria. The following results were obtained: (1) Upon addition, Ag(+) instantly induced mitochondrial swelling and acceleration of respiration. (2) Cyclosporine A, a specific inhibitor of classical PT, was ineffective against the effect of Ag(+), indicating that silver ions induced non-classic PT. (3) Sulfhydryl reagents such as reduced glutathione completely inhibited the effects of Ag(+) on the mitochondria. (4) Experimental results using polyethylene glycol indicated that Ag(+) induced opening of a pore in the inner mitochondrial membrane, which could be PTP of another open state or a distinct pore. (5) Electron microscopic analysis of mitochondria treated with Ag(+) showed a novel mitochondrial configuration that was apparently different from that of normal mitochondria or Ca(2+)-treated mitochondria. (6) Ag(+) also induced the release of apoptogenic cytochrome c in a CsA-insensitive but GSH-sensitive manner. These results suggest that Ag(+) promotes a nonclassical permeability increase in the mitochondrial inner membrane that is clearly distinguishable from the classical PT and releases apoptogenic cytochrome c in a classical PT-independent manner.
已知多种试剂可打开线粒体通透性转换孔（PTP）并诱导通透性转换（PT），从膜间隙释放凋亡蛋白并触发细胞凋亡。在本研究中，我们检测了已知具有细胞毒性的巯基反应性重金属银离子（Ag(+)）对分离的大鼠肝线粒体的影响。获得了以下结果：（1）加入Ag(+)后，立即诱导线粒体肿胀并加速呼吸。（2）环孢素A，一种经典PT的特异性抑制剂，对Ag(+)的作用无效，表明银离子诱导的是非经典PT。（3）巯基试剂如还原型谷胱甘肽完全抑制了Ag(+)对线粒体的作用。（4）使用聚乙二醇的实验结果表明，Ag(+)诱导线粒体内膜上一个孔的开放，该孔可能是另一种开放状态的PTP或一个不同的孔。（5）对用Ag(+)处理的线粒体进行电子显微镜分析显示出一种新的线粒体形态，明显不同于正常线粒体或经Ca(2+)处理的线粒体。（6）Ag(+)还以一种对环孢素A不敏感但对谷胱甘肽敏感的方式诱导凋亡细胞色素c的释放。这些结果表明，Ag(+)促进线粒体内膜非经典的通透性增加，这与经典PT明显不同，并以一种不依赖经典PT的方式释放凋亡细胞色素c。
