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

描述（由申请人提供）：线粒体是能量代谢、细胞凋亡、信号传导和离子稳态的中心舞台。我们对这种细胞器的了解大多来自于对细胞器遗传疾病的研究。这些是毁灭性的疾病，是由于mtDNA或核DNA的遗传缺陷导致线粒体呼吸链（氧化磷酸化（OXPHOS）的核心机制）出现故障。几乎所有的器官系统都会受到影响。OXPHOS病影响约1:50 000活产，具有毁灭性——诊断极其困难，需要多名医生会诊并进行侵入性活组织检查，目前尚无有效的治疗方法。一小部分线粒体OXPHOS疾病是母系遗传的，但绝大多数是由于核基因突变，其中许多尚未确定。我们的研究小组最近使用整合蛋白质组学来定义编码线粒体蛋白质组的约1100个核基因-这些基因代表了OXPHOS疾病的近乎全面的候选基因集合。我们现在正在应用下一代测序技术，对100多名临床证据为OXPHOS病的患者的所有约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拯救研究，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、经过验证的疾病基因分配到线粒体途径中OXPHOS生物发生的特定步骤。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体。如果成功，我们的工作将提高我们在这些致残疾病中建立分子诊断的能力。我们发现的基因和途径可能会揭示一些非常常见的疾病的发病机制，如神经退行性疾病、糖尿病和婴儿死亡率，这些疾病可能源于该细胞器的功能障碍。最后，该项目有望通过揭示OXPHOS系统组装和生物发生所需的新蛋白质，对基础生物化学产生有价值的影响。

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.