Increase of mitochondria and mitochondrial DNA in response to oxidative stress in human cells
Increase of mitochondria and mitochondrial DNA in response to oxidative stress in human cells
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DOI：
10.1042/0264-6021:3480425
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发表时间：
2000-06-01
影响因子：
4.1
通讯作者：
Wei, YH
中科院分区：
文献类型：
--
作者：
Lee, HC;Yin, PH;Wei, YH
线粒体呼吸功能在线粒体疾病患者的靶组织中受损，在人体各种组织中随年龄增长而下降。人们普遍认为，呼吸链缺陷导致线粒体中活性氧和自由基的产生增加。最近，我们已经证明线粒体DNA （mtDNA）的拷贝数在老年人类受试者的肺组织中增加。mtDNA拷贝数被认为是通过一种反馈机制来增加的，这种机制补偿了线粒体中含有突变mtDNA和缺陷呼吸系统的缺陷。然而，具体机制尚不清楚。在这项研究中，我们用浓度为90-360 μ m的H2O2处理人肺成纤维细胞系MRC-5，经过24-72 h的处理，我们发现细胞在G(0)期和G(1)期被阻滞，但线粒体质量和mtDNA含量呈浓度和时间依赖性显著增加。此外，还发现由丁硫氨酸亚砜引起的氧化应激也会引起处理细胞线粒体质量的增加。增加线粒体重要染料罗丹明123的摄取和增强四唑[MTT， 3-（4,5-二甲基噻唑-2-基）-2,5-二苯基- 2h -溴化四唑]的还原表明H2O2处理增加的线粒体是功能性的。此外，米莫辛、洛伐他汀和染料木黄酮诱导的细胞周期阻滞细胞也观察到线粒体质量的增加。综上所述，这些发现表明，线粒体质量和mtDNA含量的增加是人类细胞通过细胞周期阻滞响应内源性或外源性氧化应激的早期分子事件。
Mitochondrial respiratory function is impaired in the target tissues of patients with mitochondrial diseases and declines with age in various human tissues. It is generally accepted that respiratory-chain defects result in enhanced production of reactive oxygen species and free radicals in mitochondria. Recently, we have demonstrated that the copy number of mitochondrial DNA (mtDNA) is increased in the lung tissues of elderly human subjects. The mtDNA copy number was suggested to be increased by a feedback mechanism that compensates for defects in mitochondria harbouring mutated mtDNA and a defective respiratory system. However, the detailed mechanism remains unclear. In this study, we treated a human lung fibroblast cell line, MRC-5, with H2O2 at concentrations of 90-360 mu M. After the treatment for 24-72 h, we found that cells were arrested at G(0) and G(1) phases but that mitochondrial mass and mtDNA content were significantly increased in a concentration- and time-de-pendent manner. Moreover, the oxidative stress induced by buthionine sulphoximine was also found to cause an increase in mitochondrial mass of the treated cells. Increased uptake of a vital mitochondrial dye Rhodamine 123 and enhanced tetrazolium [MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H- tetrazolium bromide] reduction revealed that the mitochondria increased by H2O2 treatment were functional. In addition, the increase in the mitochondrial mass was also observed in cell-cycle-arrested cells induced by mimosine, lovastatin and genistein. Taken together, these findings suggest that the increase in mitochondrial mass and mtDNA content are the early molecular events of human cells in response to endogenous or exogenous oxidative stress through cell-cycle arrest.