Novel Roles for COX Assembly Factors in Mitochondrial Homeostasis

线粒体是亚细胞隔间，负责产生我们细胞生存所需的大部分能量。除了在能量生产中的核心作用外，线粒体对细胞程序性死亡至关重要，程序性细胞死亡是每个活细胞生死平衡的重要组成部分。我的实验室专注于细胞色素氧化酶(COX)，这是线粒体呼吸链的末端电子受体，是产生能量的机械。除了它的蛋白质亚基，COX还需要大量的辅助蛋白质，为酶的组装提供铜和血红素A。在最近的授权期，我们发现Cox17在野生型固定相酵母中含量更高，并且Cox17的缺失导致无法在固定相酵母中诱导细胞凋亡，这首次表明这种更为人所知的线粒体铜伴侣蛋白也可能在细胞质量控制中发挥作用。此外，我们还发现，缺乏COX组装也会导致氧化应激增加。*在即将到来的授权期，我们将继续使用酿酒酵母作为模型，在线粒体和更广泛的细胞环境中研究COX组装缺陷的后果。酵母已被证明是更好地了解线粒体是如何形成和功能的一个很好的模型，它直接应用于我们对涉及线粒体功能障碍的人类疾病的理解，如神经退行性变和癌症。我们使用已停止生长和分裂的固定相酵母，对于了解线粒体缺陷在涉及人类组织(如神经元)停止生长和分裂的疾病中的后果特别相关。使用酵母分子细胞生物学和生物化学的标准方法，并利用我们的大量突变体库，我们将确定Cox17如何在诱导细胞凋亡中发挥作用，以及哪些其他分子参与了Cox17的这一新功能。我们还将确定固定相Cox17丰度增加的分子基础，以及COX组装的丢失如何导致固定相酵母中铜锌超氧化物歧化酶的蛋白质数量和酶活性的变化。*建议的实验是我实验室长期NSERC资助计划的继续，将提高我们对COX组装缺陷的细胞后果的理解，并与我们对人类COX缺陷的分子基础的理解直接相关。这项工作还将对我们理解神经退行性疾病和癌症的病因和病理生理学产生影响，因为固定相酵母是通常涉及这些人类疾病的终末分化组织的合适模型。

Mitochondria are sub-cellular compartments responsible for producing the bulk of the energy our cells need for survival. In addition to their central role in energy production, mitochondria are crucial for programmed cell death, an important component of the life-death balance for every living cell. My lab is focusing on cytochrome oxidase (COX), the terminal electron acceptor of the mitochondrial respiratory chain, the energy-producing machinery. In addition to its protein subunits, COX also requires a host of accessory proteins that provide copper and heme A for enzyme assembly. In the most recent granting period, we have found that Cox17 is more abundant in wild-type stationary phase yeast and that loss of Cox17 results in an inability to induce apoptosis in stationary phase yeast, suggesting for the first time that this small protein, better known as a mitochondrial copper chaperone, may also have role in cellular quality control. In addition, we have found that a lack of assembled COX also leads to an increase in oxidative stress.******In the coming granting period, we will continue using the yeast, Saccharomyces cerevisiae, as a model for studying the consequences of a COX assembly defect in both the mitochondrial and broader cell context. Yeast has proven to be an excellent model for better understanding how mitochondria are formed and function, with direct application to our understanding of human diseases that involve dysfunctional mitochondria, such as neurodegeneration and cancers. Our use of stationary phase yeast, which have ceased growing and dividing, is particularly relevant to understanding the consequences of mitochondrial defects in diseases involving human tissues that have ceased growing and dividing, such as neurons. Using standard approaches in yeast molecular cell biology and biochemistry and taking advantage of our large mutant collection, we will determine how Cox17 acts in the induction of apoptosis and what other molecules are involved in this novel function for Cox17. We will also determine the molecular basis for the increased abundance of Cox17 at stationary phase and how a loss of COX assembly leads to changes in the amount of protein and enzymatic activity of the Cu,Zn-superoxide dismutase in stationary phase yeast.******The proposed experiments are the continuation of the long-standing NSERC-funded program in my lab and will improve our understanding of the cellular consequences of COX assembly defects, as well as having direct relevance to our understanding of the molecular bases for inherited human COX deficiencies. This work will also have implications for our understanding of the etiologies and pathophysiology underlying neurodegenerative diseases and cancer, given that stationary phase yeast are an appropriate model for the terminally differentiated tissues typically involved in these human diseases.**