Mitochondria and Mutagenesis

线粒体功能障碍是癌症的特征之一。然而，人们对此知之甚少。 线粒体功能障碍会导致癌症的发生。我们在这项提案中描述的研究提出了一种新的 线粒体在防止核基因组突变中的作用--人类的一项重要事件 致癌。以酿酒酵母为模式生物，我们分析了 在核基因组的突变中破坏线粒体的功能。我们测量了它们的频率 刀豆素抗性菌落作为核基因组诱变指标的研究。我们的数据表明 线粒体功能障碍导致核基因组突变(I)缺乏完整线粒体的突变株 线粒体基因组(Rho？或p？)或线粒体DNA缺失(Rho“或p”)(线粒体遗传 功能障碍)和(Ii)野生型酵母氧化磷酸化被抗霉素A阻断时 (线粒体代谢功能障碍，MMD)。MMD和MGD细胞的核突变频率 分别高于未经处理的对照和野生型细胞。MGD导致下降 细胞内ROS水平。相反，MMD导致细胞内活性氧水平升高。 (ROS)。我们证明了MGD引起的核基因组突变依赖于Rev1、Revs或 Rev7基因产物，均与复制后修复(PRR)有关。然而，核基因组突变 由于MMD不涉及Rev1、RevS或Rev7基因。此外，我们提供了Rtg2的证据 参与线粒体到细胞核逆行反应通路的蛋白质(逆行2)保护细胞免受 核基因组突变。基于这些观察，我们假设线粒体保护 并采用多种途径来保护核基因组免受突变。 我们提出了4个具体目标来检验所提出的假设。在所有情况下，我们都有初步数据表明 为提出的具体目标提供依据。这些具体目标是：1)确立 线粒体致核基因组突变中的线粒体-核逆行反应通路 功能障碍2)确定氧化应激反应受损是否导致核基因组 线粒体功能障碍引起的突变3)决定复制后修复途径在 线粒体功能障碍引起的核基因组突变4)决定核基因组的性质 线粒体功能障碍引起的突变我们拟议的研究应该能提供对分子的洞察力 线粒体功能障碍所致核基因组突变的遗传机制 对人类癌症和其他疾病的意义。

Mitochondrial dysfunction is one of the hallmarks of cancer. However, very little is known about how mitochondrial dysfunction leads to carcinogenesis. Our studies described in this proposal suggest a novel role for mitochondria in protecting cells from nuclear genome mutagenesis, an important event in human carcinogenesis. Using Saccharomyces cerevisiae as a model organism, we analyzed the consequences of disrupting mitochondrial function on mutagenesis of the nuclear genome. We measured the frequency of canavanine resistant colonies as an indicator of nuclear genome mutagenesis. Our data demonstrate that mitochondrial dysfunction leads to mutation in the nuclear genome (i) in mutant strains lacking the entire mitochondrial genome (rho¿ or p¿) or those with deleted mitochondrial DNA (rho" or p") (mitochondrial genetic dysfunction, MGD) and (ii) when oxidative phosphorylation is blocked in wild type yeast by antimycin A (mitochondrial metabolic dysfunction, MMD). The nuclear mutation frequencies in both MMD and MGD cells were higher compared to untreated control and wild type cells respectively. MGD led to decreased intracellular levels of ROS. In contrast MMD led to increased intracellular levels of reactive oxygen species (ROS). We demonstrate that nuclear genome mutagenesis due to MGD is dependent on REV1, REVS or REV7 gene products, all implicated in post-replication repair (PRR). However, nuclear genome mutagenesis due to MMD does not involve REV1, REVS or REV7 genes. Furthermore, we provide evidence that Rtg2 protein (retrograde 2) involved in mitochondria-to-nucleus retrograde response pathway protect cells from nuclear genome mutagenesis. Based on these observations we hypothesize that mitochondria protect and employ multiple pathways to guard the nuclear genome against mutagenesis. We propose 4 specific aims to test the proposed hypothesis. In all cases we have preliminary data that provide the basis for the proposed specific aims. These specific aims are:1) Establish the role of mitochondria-to-nucleus retrograde response pathway in nuclear genome mutagenesis due to mitochondrial dysfunction 2) Determine whether compromised oxidative stress response leads to nuclear genome mutagenesis due to mitochondrial dysfunction 3) Determine the role of post-replication repair pathway in nuclear genome mutagenesis due to mitochondrial dysfunction 4) Determine the nature of nuclear genome mutagenesis due to mitochondrial dysfunction Our proposed study should provide insight into the molecular genetic mechanisms of nuclear genome mutagenesis due to mitochondrial dysfunction that is of fundamental significance to human cancer and other diseases.