Chinta Shankar J, Rane Anand, Yadava Nagendra, Andersen Julie K, Nicholls David G, Polster Brian M
The Buck Institute for Age Research, Novato, CA 94945, USA.
Free Radic Biol Med. 2009 Apr 1;46(7):939-47. doi: 10.1016/j.freeradbiomed.2009.01.010.
Apoptosis-inducing factor (AIF)-deficient harlequin (Hq) mice undergo neurodegeneration associated with a 40-50% reduction in complex I level and activity. We tested the hypothesis that AIF and complex I regulate reactive oxygen species (ROS) production by brain mitochondria. Isolated Hq brain mitochondria oxidizing complex I substrates displayed no difference compared to wild type (WT) in basal ROS production, H2O2 removal, or ROS production stimulated by complex I inhibitors rotenone or 1-methyl-4-phenylpyridinium. In contrast, ROS production caused by reverse electron transfer to complex I was attenuated by approximately 50% in Hq mitochondria oxidizing the complex II substrate succinate. Basal and rotenone-stimulated rates of H2O2 release from in situ mitochondria did not differ between Hq and WT synaptosomes metabolizing glucose, nor did the level of in vivo oxidative protein carbonyl modifications detected in synaptosomes, brain mitochondria, or homogenates. Our results suggest that AIF does not directly modulate ROS release from brain mitochondria. In addition, they demonstrate that in contrast to ROS produced by mitochondria oxidizing succinate, ROS release from in situ synaptosomal mitochondria or from isolated brain mitochondria oxidizing complex I substrates is not proportional to the amount of complex I. These findings raise the important possibility that complex I contributes less to physiological ROS production by brain mitochondria than previously suggested.
凋亡诱导因子（AIF）缺陷型花斑鼠（Hq）会发生神经退行性变，同时复合物I的水平和活性降低40 - 50%。我们检验了AIF和复合物I调节脑线粒体活性氧（ROS）生成的假说。与野生型（WT）相比，分离出的氧化复合物I底物的Hq脑线粒体在基础ROS生成、H2O2清除或由复合物I抑制剂鱼藤酮或1 - 甲基 - 4 - 苯基吡啶鎓刺激的ROS生成方面没有差异。相反，在氧化复合物II底物琥珀酸的Hq线粒体中，由反向电子传递至复合物I所引起的ROS生成减少了约50%。在代谢葡萄糖的Hq和WT突触体中，原位线粒体H2O2释放的基础速率和鱼藤酮刺激速率没有差异，在突触体、脑线粒体或匀浆中检测到的体内氧化蛋白羰基修饰水平也没有差异。我们的结果表明，AIF不会直接调节脑线粒体的ROS释放。此外，结果表明，与氧化琥珀酸的线粒体产生的ROS不同，原位突触体线粒体或分离出的氧化复合物I底物的脑线粒体释放的ROS与复合物I的量不成正比。这些发现增加了一种重要的可能性，即复合物I对脑线粒体生理性ROS生成的贡献比之前认为的要小。
