Mechanism of Generation of Reactive Oxygen Species from Mitochondria by Nuclear Signal

活性氧（ROS）似乎是多种疾病和发病机制的诱导物，例如衰老、神经退行性疾病，即，自从我们报道了ROS的线粒体产生控制细胞凋亡的第一个证据（Majima等，JBC 1998）以来，我们研究了ROS和细胞凋亡之间的关系，所述细胞凋亡由辐射、蓝光暴露、缺血再灌注、化疗剂治疗（博来霉素和顺铂）引起。本研究利用DNA微阵列技术进一步研究了线粒体DNA缺失细胞（Rho 0细胞）核基因组的激活情况，发现Rho 0细胞核基因组中2236个基因中有402个发生了改变，提示线粒体与细胞核之间可能存在着一种相互作用的信使。为了测试p53和hsp70在串扰信使中的可能作用，我们通过这些RNAi抑制mRNA表达水平，并研究线粒体ROS产生的变化。转染MnSOD RNAi载体后，ROS水平明显升高，而转染p53和hsp70 RNAi载体后，ROS水平无明显变化，提示p53和HSP70不是干扰信号的候选者。

Reactive oxygen species (ROS) seem to be an inducer of various diseases and pathogenesis such as aging, neuro-degenerative diseases, i.e., Alzheimer's disease, Parkinson's disease etc. Since we have reported the first evidence that mitochondrial generation of ROS controls apoptosis (Majima et al. JBC 1998), we have investigated the relationship between ROS and apoptosis, caused by radiation, blue light exposure, ischemia reperfusion, chemotherapeutic agent treatments (bleomycin and cis-platinum). In every experiments tested, we have confirmed the relationship among ROS, lipid peroxidation and apoptosis.In this study, we further investigated nuclear genome activation in mitochondrial DNA lacking cells (Rho0 cells) by DNA microarray, and found out that 402 genes out of 2236 nuclear genes were changed in Rho0 cells, suggesting a possible cross-talk messengers between mitochondria and nucleus. To test a possible role of p53 and hsp70 on the cross-talk messenger, we suppressed mRNA expression level by these RNAi, and studied change of ROS generation from mitochondria. A positive increase in ROS by transfection of MnSOD RNAi vectors was found, while no change of ROS by transfection of p53 or hsp70 RNAi vectors were revealed, suggesting p53 and HSP70 are not candidate of the cross-talk messenger.