Tang Ho Lam, Le Anh-Huy Phan, Lung Hong Lok
Department of Biology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.
Biochem J. 2006 May 15;396(1):1-5. doi: 10.1042/BJ20060241.
Accumulating evidence indicates the potential role of actin cytoskeleton in facilitating the mitochondrial recruitment of various pro-apoptotic proteins from the cytosol to initiate apoptosis. In the present paper, we report the observation of the increase in mitochondrial association of actin in early apoptosis. Using cell fractionation and Western blot analysis, we found that mitochondrial accumulation of beta-actin occurred before the mitochondrial insertion of Bax and release of cytochrome c in apoptosis. The mitochondrial accumulation of beta-actin was observed with various apoptotic stimuli in various cell lines, suggesting that this is a general apoptotic phenomenon in mammalian systems. Using fluorescence microscopy, we have shown that an apoptotic induction triggered the reorganization of the F-actin (filamentous actin) network with an increase in the association with mitochondria, which was observed before mitochondrial fission and nuclear condensation. Perhaps actin could contribute to the initiation of apoptosis by enabling cytosolic pro-apoptotic proteins to be carried to mitochondria by the cytoskeleton-driven trafficking system.
越来越多的证据表明，肌动蛋白细胞骨架在促进各种促凋亡蛋白从细胞质向线粒体募集以启动细胞凋亡过程中具有潜在作用。在本文中，我们报告了在早期细胞凋亡过程中观察到肌动蛋白与线粒体的结合增加。通过细胞分级分离和蛋白质印迹分析，我们发现β-肌动蛋白的线粒体积累发生在凋亡过程中Bax插入线粒体和细胞色素c释放之前。在各种细胞系中，用各种凋亡刺激均观察到β-肌动蛋白的线粒体积累，这表明这是哺乳动物系统中的一种普遍凋亡现象。利用荧光显微镜，我们已经表明，凋亡诱导引发了F-肌动蛋白（丝状肌动蛋白）网络的重组，同时与线粒体的结合增加，这一现象在线粒体分裂和核浓缩之前就已观察到。也许肌动蛋白可以通过使细胞溶质促凋亡蛋白通过细胞骨架驱动的运输系统被携带到线粒体，从而有助于细胞凋亡的启动。
