Gong B, Chen Q, Almasan A
Department of Cancer Biology, Lerner Research Institute, The Cleveland Clinic Foundation, Ohio 44195, USA.
Radiat Res. 1998 Nov;150(5):505-12.
Radiation-induced gene expression was examined in cells of a radioresistant human glioblastoma cell line, T98G, using RNA fingerprinting by arbitrary primer polymerase chain reaction. Three of the differentially induced transcripts were cloned and identified as the mitochondrially encoded cytochrome c oxidase (MTCO) subunits 1 and 2, and NADH dehydrogenase subunit 4. The levels of all three mRNAs were increased 1 h after irradiation, with elevated expression persisting for at least 24 h. Similar to radiation, other oxidants lead to induction of MTCO1, an effect which could be prevented by the antioxidant pyrrolidine dithiocarbamate. These results indicate that the increase in mitochondrial gene expression is mediated by oxidative stress. Mitochondria could be a target of signaling by ionizing radiation and oxidants since it is known to be at the site of cellular oxidative stress. The proteins encoded by MTCO1 and other mitochondrial mRNAs characterized are part of the mitochondrial respiratory chain which produces adenosine triphosphate through the process of oxidative phosphorylation. Adenosine triphosphate levels and the mitochondrial membrane potential were found to be increased significantly after irradiation, while mitochondrial mass and mitochondrial DNA levels were unaffected. These data demonstrate the specificity of changes in mitochondrial activity and gene expression after irradiation.
利用任意引物聚合酶链反应进行RNA指纹分析，在耐辐射的人胶质母细胞瘤细胞系T98G的细胞中检测辐射诱导的基因表达。克隆了三个差异诱导的转录本，并鉴定为线粒体编码的细胞色素c氧化酶（MTCO）亚基1和2以及NADH脱氢酶亚基4。照射后1小时，所有三种mRNA的水平均升高，且表达升高持续至少24小时。与辐射相似，其他氧化剂也会导致MTCO1的诱导，抗氧化剂吡咯烷二硫代氨基甲酸盐可阻止这种效应。这些结果表明线粒体基因表达的增加是由氧化应激介导的。线粒体可能是电离辐射和氧化剂信号传导的靶点，因为已知它位于细胞氧化应激的部位。MTCO1和其他已鉴定的线粒体mRNA编码的蛋白质是线粒体呼吸链的一部分，该呼吸链通过氧化磷酸化过程产生三磷酸腺苷。照射后发现三磷酸腺苷水平和线粒体膜电位显著升高，而线粒体质量和线粒体DNA水平未受影响。这些数据证明了照射后线粒体活性和基因表达变化的特异性。
