Barth syndrome: Evaluating cardiolipin mediated tissue specific oxidative phosphorylation dysfunction

巴特综合征：评估心磷脂介导的组织特异性氧化磷酸化功能障碍

• 批准号: 9759571
• 负责人: Arianna Lee Franca Anzmann
• 金额: $ 4.5万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9759571
• 关键词: 3-Methylglutaconic aciduria type 2; Address; Affect; Apoptotic; Basic Science; Biological Assay; Brain; Cardiac; Cardiac Myocytes; Cardiolipins; Cardiomyopathies; Cell model; Cells; Complex; Crista ampullaris; Diagnostic; Disease; Enzyme Stability; Enzymes; Functional disorder; Gene Expression; Genes; Genetic Diseases; Genetic Transcription; Hereditary Disease; Individual; Inner mitochondrial membrane; Knowledge; Laboratory Research; Leigh Disease; Link; Mediating; Metabolic; Mitochondria; Mitochondrial Diseases; Monitor; Myocardium; Myopathy; NADH; NADH dehydrogenase (ubiquinone); Neurologic; Neurons; Neutropenia; Outcome; Oxidative Phosphorylation; Patients; Phospholipid Metabolism; Phospholipids; Play; Proteins; Rare Diseases; Research; Respiratory Chain; Role; Site; Skeletal Muscle; Specificity; Testing; Therapeutic; Time; Tissues; Transacylase; Translating; Variant; Work; base; career; clinically relevant; induced pluripotent stem cell; insight; lymphoblastoid cell line; mRNA Expression; mitochondrial dysfunction; monolysocardiolipin; novel; protein expression; screening; skeletal; skills; therapeutic target; translational approach

Project Summary Barth Syndrome (BTHS), is an X-linked inborn error of mitochondrial phospholipid metabolism, caused by variants in the gene tafazzin (TAZ). TAZ encodes for a transacylase involved in the final remodeling step of cardiolipin (CL), a phospholipid localized to the inner mitochondrial membrane with key roles in cristae formation, organization of the mitochondrial respiratory chain, and in the apoptotic cascade. Both TAZ and CL are ubiquitously expressed in all tissues, however the CL content is tissue specific; brain CL is characterized by a diversified array of acyl chains including polyunsaturated chains, whereas in the cardiac and skeletal muscle CL is predominantly characterized by the tetralinoleoyl form. As is typical of most primary mitochondrial diseases, BTHS is a multisystem disorder, characterized by cardiomyopathy, skeletal myopathy, and neutropenia among other features. However, in sharp contrast to many mitochondrial diseases, BTHS has minimal neurological burden. Thus, understanding the mechanisms of tissue specificity in BTHS has the potential to provide great insight into the role of specific CL content on mitochondrial function, as well as to offer novel treatment targets for BTHS. In my preliminary work with a novel TAZ deficient cellular model, I found that complex I of the respiratory chain is dysregulated at the protein and metabolic level. Based on this, I hypothesize that complex I is a major site of oxidative phosphorylation (OXPHOS) dysfunction in tissues affected in BTHS. Dysregulation of complex I in BTHS is a particularly interesting finding, because other complex I disorders, including Leigh Disease, have a significant neurological impact. Therefore, I further hypothesize that the tissue specific CL content of neurologic tissue spares it from this dysfunction. To address this hypothesis, I propose two specific aims. Aim 1: To determine the impact of TAZ deficiency, and therefore abnormal CL content, on complex I function. I will first investigate the effect of the reduced expression of Complex I proteins on enzyme stability and function. Then I will determine whether the assembly factor NDUFAF1 plays a prominent role in the reduced expression of complex I proteins, and if the reduced NDUFAF1 expression is due to dysregulation at the transcriptional level. Aim 2: To understand the role of tissue specificity of CL content on the pathophysiology of BTHS. I will first differentiate TAZ deficient iPSCs, iPSC TAZ∆50, into cardiomyocytes and neurons in order to characterize and compare complex I dysregulation by assessing NDUFAF1 protein expression, NADH/NAD+ ratio, and complex I enzyme stability/function. Then, I will determine if TAZ deficient neurons display altered CL as compared to WT neurons, and if the lack of altered CL content in TAZ deficient neurons reflects a smaller role for TAZ in neuronal CL remodeling. This project proposal combines basic science and translational approaches to unravel cellular pathophysiology and identify potential therapeutic targets for a rare disease. The skills I will acquire as I complete this research will prepare me for a career in therapeutic discovery for rare genetic conditions.

项目摘要 Barth综合征（BTHS）是线粒体磷脂代谢的X连锁先天误差，由 Gene Tafazzin（TAZ）中的变体。 TAZ编码参与最终重塑步骤的跨席地。 Cardiolipin（CL），一种磷脂，位于内部线粒体膜中，在Cristae中具有关键作用 形成，线粒体呼吸链的组织以及凋亡的级联反应。 TAZ和CL 在任何时候都无处不在，但是CL含量是组织特异性的。大脑CL的特征 通过一系列多样化的酰基链，包括多不饱和链，而在心脏和骨骼中 肌肉CL的主要特征是四丁乙酰烯酰基形式。与大多数主要线粒体的典型代表 疾病，BTHS是一种多系统疾病，其特征是心肌病，骨骼肌病和 中性粒细胞减少症。但是，与许多线粒体疾病形成鲜明对比，BTHS具有 最小的神经科伯嫩。那就是了解BTHS中组织特异性的机制具有 有可能深入了解特定CL含量对线粒体功能的作用以及 为BTH提供新颖的治疗目标。在我使用新型TAZ缺陷细胞模型的初步工作中，I 发现呼吸链的复合物在蛋白质和代谢水平上失调。基于此， 我假设该复合物是I是氧化磷酸化（OXPHOS）功能障碍的主要部位 在BTH中受到影响的组织。 BTHS中复杂I的失调是一个特别有趣的发现，因为 其他复杂的I疾病，包括Leigh疾病，具有重大的神经系统影响。因此，我进一步 假设神经组织的组织特异性CL含量从这种功能障碍中释放了它。到 解决这个假设，我提出了两个具体目标。目标1：确定TAZ缺乏的影响，并 因此，关于复杂I功能的异常Cl含量。我将首先研究减少的效果 复合I蛋白在酶稳定性和功能上的表达。然后我将确定是否 因子NDUFAF1在复杂I蛋白的降低表达中起着重要的作用，如果降低 NDUFAF1表达是由于转录水平的失调引起的。目标2：了解 CL含量在BTH的病理生理学上的组织特异性。我将首先区分TAZ缺陷IPSC， IPSCTAZΔ50，进入心肌细胞和神经元，以表征和比较复合物I失调 通过评估NDUFAF1蛋白表达，NADH/NAD+比和复杂的I酶稳定性/功能。然后， 与WT神经元相比 TAZ缺乏神经元中CL含量的改变反映了TAZ在神经元CL重塑中的作用较小。这 项目建议结合了基础科学和转化方法，以阐明细胞病理生理学和 确定罕见疾病的潜在治疗靶标。我完成这项研究将获得的技能 我为罕见遗传状况的治疗发现工作做好准备。