Human Mitochondrial Disease: From Novel Gene Variants to Causality and Function

描述(申请人提供)：线粒体是能量代谢、细胞凋亡、信号和离子动态平衡的中心阶段。我们对这种细胞器的大部分了解都来自于对细胞器遗传紊乱的研究。这些是毁灭性的疾病，是由于线粒体DNA或核DNA的遗传缺陷导致线粒体呼吸链故障，线粒体呼吸链是氧化磷酸化(OXPHOS)的核心机制。几乎所有的器官系统都会受到影响。据估计，OXPHOS病影响着1：5000的活产，并且是毁灭性的--诊断极其困难，需要多名医生会诊和侵入性活组织检查，而且目前还没有有效的治疗方法。线粒体OXPHOS疾病中有一小部分是母系遗传的，但绝大多数是由于核基因的突变，其中许多尚未确定。我们的研究团队最近使用集成蛋白质组学来定义编码线粒体蛋白质组的~1100个核基因-这些基因代表了OXPHOS病候选基因的近乎全面的集合。我们现在正在应用下一代测序技术对100多名有临床证据的OXPHOS病患者的所有~1100个核基因进行测序。在拟议的项目中，我们计划(1)从我们通过医学下一代测序发现的基因变异开始，并进行cDNA抢救研究，以创建经过实验验证的线粒体OXPHOS疾病基因目录，然后(2)将新的、验证的疾病基因分配到OXPHOS生物发生的线粒体途径的特定步骤。我们的工作将利用我们通过ARRA资助的下一代医学测序发现的丰富的新变种。如果成功，我们的工作将提高我们在这些严重疾病中建立分子诊断的能力。我们发现的基因和途径可能有助于深入了解一些非常常见的疾病的发病机制，如神经退行性变、糖尿病和婴儿死亡，这些疾病可能源于这个细胞器的功能障碍。最后，该项目有望通过揭示OXPHOS系统的组装和生物发生所需的新蛋白质，在基础生物化学方面产生有价值的影响。

DESCRIPTION (provided by applicant): The mitochondrion is the center stage for energy metabolism, apoptosis, signaling, and ion homeostasis. Much of what we know about this organelle comes from studying genetic disorders of the organelle. These are devastating disorders that are due to genetic defects in the mtDNA or the nuclear DNA that give rise to a malfunctioning mitochondrial respiratory chain, the core machinery for oxidative phosphorylation (OXPHOS). Virtually all organ systems can be affected. OXPHOS disease affects an estimated 1:5000 live births and is devastating - it is extremely difficult to diagnose, requiring consultation by multiple physicians and invasive biopsies, and at present, and no effective therapies are available. A small fraction of mitochondrial OXPHOS disorders are maternally inherited, but the vast majority are due to mutations in nuclear genes, many of which have yet to be identified. Our research team has recently used integrated proteomics to define the ~1100 nuclear genes that encode the mitochondrial proteome - these genes represent a near-comprehensive collection of candidate genes for OXPHOS disease. We are now applying next-generation sequencing technology to sequence all ~1100 nuclear genes in a panel of over 100 patients with clinical evidence of OXPHOS disease. In the proposed project, we plan to (1) begin with the gene variants we discover through medical next-generation sequencing and perform cDNA rescue studies to create an experimentally validated catalog of mitochondrial OXPHOS disease genes and then (2) assign novel, validated disease genes to specific steps in the mitochondrial pathway for OXPHOS biogenesis. Our work will capitalize on the rich set of new variants we are discovering through ARRA funded next generation medical sequencing. If successful, our work will improve our ability to establish molecular diagnoses in these crippling disorders. The genes and pathways we discover may shed insights into the pathogenesis of some very common diseases, such as neurodegeneration, diabetes, and infantile mortality, which may stem from dysfunction in this organelle. Finally, this project promises to have a valuable impact in fundamental biochemistry by revealing new proteins required for the assembly and biogenesis of the OXPHOS system.