Zemlyak Ilona, Brooke Sheila M, Singh Maneesh H, Sapolsky Robert M
Department Biological Sciences, 371 Serra Street, Stanford University, Stanford, CA, United States.
Neurosci Lett. 2009 Apr 10;453(3):182-5. doi: 10.1016/j.neulet.2009.02.020. Epub 2009 Feb 13.
Apoptosis arises from neuronal damage following an ischemic insult. Apoptosis-inducing factor (AIF) is a protein released from mitochondria in response to pro-apoptotic signals which then translocates to the nucleus and triggers DNA fragmentation. In parallel with this, pro-apoptotic signals cause the release of cytochrome c from mitochondria, activating caspase-dependent apoptosis. During post-ischemic reperfusion, reactive oxygen species (ROS) are formed in excess in mitochondria and can play a role in initiating apoptosis. In cultures, ROS are formed during post oxygen glucose deprivation (OGD) normoxia/normoglycemia that is used as a model for ischemia. In this study, we delivered viral vectors to overexpress antioxidants (GPX, catalase, CuZnSOD, or MnSOD) in mixed cortical cultures, in order to investigate the effects of ROS-reduction on the release of cytochrome c and AIF. Overexpression of MnSOD, CuZnSOD, catalase or GPX all prevented AIF translocation from mitochondria to the nucleus. Potentially, this could reflect broadly non-specific protection due to reducing ROS load. Arguing against this, overexpression of the same antioxidants did not inhibit cytochrome c release. These findings suggest a specific interaction between ROS formation and the caspase-independent route of apoptosis.
凋亡源于缺血性损伤后的神经元损伤。凋亡诱导因子（AIF）是一种从线粒体释放的蛋白质，响应促凋亡信号，然后转移到细胞核并引发DNA片段化。与此同时，促凋亡信号导致细胞色素c从线粒体释放，激活半胱天冬酶依赖性凋亡。在缺血后再灌注期间，线粒体中会过量形成活性氧（ROS），并可在引发凋亡中发挥作用。在培养物中，ROS在作为缺血模型的氧葡萄糖剥夺（OGD）常氧/正常血糖期间形成。在本研究中，我们在混合皮质培养物中递送病毒载体以过表达抗氧化剂（谷胱甘肽过氧化物酶、过氧化氢酶、铜锌超氧化物歧化酶或锰超氧化物歧化酶），以研究降低ROS对细胞色素c和AIF释放的影响。锰超氧化物歧化酶、铜锌超氧化物歧化酶、过氧化氢酶或谷胱甘肽过氧化物酶的过表达均阻止了AIF从线粒体向细胞核的转移。这可能潜在地反映了由于降低ROS负荷而产生的广泛非特异性保护作用。与之相反的是，相同抗氧化剂的过表达并未抑制细胞色素c的释放。这些发现表明ROS形成与凋亡的半胱天冬酶非依赖性途径之间存在特定相互作用。
