Mitochondrial Anti-Oxidant Factors and Redox Status

描述(由申请人提供) 氧化应激以活性氧物种(ROS)的形式对细胞构成危险，可以破坏细胞成分。ROS可由环境来源产生，如高氧和氧化还原活性化学物质，也可由内源来源产生，如酶催化氧化还原反应。真核细胞中的大部分ROS是在线粒体中产生的，线粒体是参与多种细胞功能的重要细胞器。鉴于线粒体在细胞中的重要作用，以及它产生破坏性分子的潜力，线粒体缺陷与各种神经退行性疾病、衰老和癌症有关也就不足为奇了。然而，人们对该细胞器中对抗氧化损伤的机制知之甚少。因此，识别能够减轻线粒体氧化应激的抗氧化剂系统，并研究其与胞浆系统的联系是至关重要的。以酿酒酵母为模型系统，将通过表征线粒体抗氧化剂系统和揭示维持线粒体与胞质氧化还原平衡的机制来解决这些问题。初步结果表明，抗氧化因子谷胱甘肽还原酶通过另一种翻译机制同时作用于线粒体和胞浆。未来的研究将讨论这种双重定位机制是否决定了另外两种抗氧化因子的分布，谷氧还蛋白和蛋氨酸亚砜还原酶(目标1)。这两种蛋白质在线粒体和/或胞浆中的功能将通过检测这两种蛋白质表达变化的生理效应来解决(目标2)。最后，将通过监测关键氧化还原辅因子的氧化状态和评估氧化损伤的标记物来确定这些抗氧化因子在维持线粒体相对于胞浆中的氧化还原平衡中所起的作用(目标3)。总体而言，这些研究将解决线粒体如何在面对内源性压力和环境侮辱时保持氧化还原平衡。

DESCRIPTION (provided by applicant) Oxidative stress presents a danger to the cell in the form of reactive oxygen species (ROS) that can damage cellular components. ROS can be generated by environmental sources such as hyperoxia and redox-active chemicals, as well as by endogenous sources such as enzymatic redox reactions. Most of the ROS in the eukaryotic cell is generated in the mitochondrion, an essential organelle involved in diverse cellular functions. Given its vital role in the cell, along with its potential to generate damaging molecules, it is not surprising that mitochondrial defects are associated with a variety of neurodegenerative diseases, aging, and cancer. However, the mechanisms for combating oxidative damage in this organelle are poorly understood. It is therefore critical to identify anti-oxidant systems that specifically function to alleviate oxidative stress in mitochondria and to examine their connection with cytosolic systems. Using the yeast Saccharomyces cerevisiae as a model system, these issues will be addressed by characterizing mitochondrial anti-oxidant systems and uncovering the mechanisms for maintaining mitochondrial versus cytosolic redox balance. Initial results have indicated that the anti-oxidant factor glutathione reductase is targeted to both the mitochondria and the cytosol by an alternative translation mechanism. Future studies will address whether this dual localization mechanism dictates the distribution of two other anti-oxidant factors, a glutaredoxin and a methionine sulfoxide reductase (aim 1). The function of these two proteins in the mitochondria and/or the cytosol will be addressed by examining the physiological effects of altered expression of these proteins (aim 2). Finally, the role these anti-oxidant factors play in maintaining redox balance in the mitochondria versus the cytosol will be determined by monitoring the oxidation state of key redox cofactors and assessing markers of oxidative damage (aim 3). Overall, these studies will address how mitochondria maintain redox balance in the face of endogenous stresses and environmental insults.