Investigating the pathogenesis of CoQ10 deficiencies

研究 CoQ10 缺乏症的发病机制

• 批准号: 8469070
• 负责人: Catarina M. Quinzii
• 金额: $ 11.76万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8469070
• 关键词: ATP Synthesis Pathway; Accounting; Affect; Aftercare; Anabolism; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Benzoquinones; Biochemical; Bioenergetics; Biological; Blood; Candidate Disease Gene; Cell Death; Cell membrane; Cells; Cerebellar Ataxia; Clinical; Coenzyme Q10; Commit; Complex; DNA; Data; Defect; Diagnosis; Disease; Electron Transport Complex III; Electrons; Enzymes; Family; Fibroblasts; Gene Mutation; Genes; Genetic; Genetic Counseling; Growth; Hereditary Disease; Heterogeneity; Human; Individual; Inherited; Knowledge; Lipid Peroxidation; Lipids; Manganese Superoxide Dismutase; Maps; Membrane; Mentors; Mitochondria; Mitochondrial Diseases; Molecular; Molecular Genetics; Multienzyme Complexes; Muscle; Mutation; NADH dehydrogenase (ubiquinone); Natural regeneration; Nuclear; Oral; Oxidative Phosphorylation; Oxidative Stress; Pathogenesis; Pathogenicity; Pathway interactions; Patients; Pharmaceutical Preparations; Prenatal Diagnosis; Production; Proteins; RNA Interference; Radiolabeled; Reactive Oxygen Species; Regulation; Relative (related person); Reporting; Residual state; Respiratory Chain; Role; Sampling; Severities; Shapes; Siblings; Side; Single Strand Break Repair; Skin; Supplementation; Syndrome; Tail; Testing; Therapeutic; Transferase; Ubiquinone; autosomal recessive trait; base; clinical phenotype; cytochrome c; decaprenyl pyrophosphate synthetase; gene complementation; human disease; hydroxybenzoate; improved; infancy; isoprenoid; mutant; novel; overexpression; oxidation; prevent; radiotracer; response; vector

DESCRIPTION (Provided by Applicant): Coenzyme Q10 (CoQ10) is a small lipophilic molecule composed of a benzoquinone ring and a hydrophobic isoprenoid tail which is present in virtually all cell membranes. In the mitochondrial respiratory chain, CoQ10 is vital for the transport of electrons from complex I and complex II to complex III. It is also an antioxidant, membrane stabilizer, and modulator of apoptosis. Human CoQ10-deficiency has been associated with four clinical phenotypes. Patients with all forms of CoQ10-deficiency have improved with oral supplementation, therefore recognition of this treatable genetic condition is important. In the last decade, the candidate and her mentors have collected biological samples from 84 patients (71 families) with documented CoQ10 deficiency in muscle and/or fibroblasts, or suspected CoQ10 deficiency based on the clinical manifestations as well as the response to CoQ10 supplementation. A total of 54 patients (48 families) have documented CoQ10 deficiency in muscle, fibroblasts, or both. In 2006, the investigative team reported the first mutations in CoQ10 biosynthetic genes, COQ2, which encodes 4-para-hydroxybenzoate: polyprenyl transferase; and PDSS2, which encodes subunit 2 of decaprenyl diphosphate synthase. In addition, in a family with four individuals with cerebellar ataxia and CoQ10 deficiency, they identified a pathogenic mutation in the APTX gene, which encodes a protein involved in single-strand break repair. Thus, these studies have revealed that CoQ10 deficiency can be primary or secondary. Not surprisingly, CoQ10 deficiency causes defects of respiratory chain activities (reduced activities of complexes I+III and II+III). The relative importance of respiratory chain defects, ROS production, and apoptosis in the pathogenesis of CoQ10-deficiency is unknown. The investigative team studied the consequences of severe CoQ10 deficiency on bioenergetics, oxidative stress, and antioxidant defenses in cultured skin fibroblasts harboring COQ2 and PDSS2 mutations. Defects in the first two committed steps of the CoQ10 biosynthetic pathway produce different biochemical alterations. PDSS2 mutant fibroblasts have 12% CoQ10 relative to control cells and markedly reduced ATP synthesis, but do not show increased reactive oxygen species (ROS) production, signs of oxidative stress, or increased antioxidant defense markers. In contrast, COQ2 mutant fibroblasts have 30% CoQ10 with partial defect in ATP synthesis, and significantly increased ROS production and oxidation of lipids and proteins. To better understand the pathogenesis of CoQ10 deficiency, the investigative team has characterized the effects of varying severity of CoQ10 deficiency on ROS production and mitochondrial bioenergetics in cells harboring different genetic defects of CoQ10 biosynthesis. They confirmed their previous findings and further observed that the correlation between level of CoQ10 and ROS production follows a parabolic curve; 10-15% residual CoQ10 and 60-70% are not associated with significant ROS production, whereas 30-50% residual CoQ10 is associated with the maximum increases in ROS production. Moreover, increase in reactive oxygen species appears to be associated with initial hyperpolarization followed by depolarization and cell death. These data are corroborated by preliminary results of treatment with CoQ10 and other antioxidants in fibroblasts from the CoQ10 deficient patients. To better understand the pathogenesis of human CoQ10 deficiency the candidate proposes the following three specific aims: Aim 1: To identify novel genetic causes of CoQ10 deficiency. Aim 2: To understand the mitochondrial bioenergetics and oxidative stress consequences of different degrees of CoQ10 deficiency in the same genetic background, she will modulate COQ2 and PDSS2 expression using RNA interference (RNAi). Aim 3: To test ROS scavenging as a potential therapeutic strategy, she will overexpress the enzyme superoxide manganese dismutase (MnSOD) in COQ2 mutant fibroblasts and will assess level of ROS, oxidative stress, and apoptosis. NARRATIVE: Defects of mitochondria cause diverse human diseases. A subtype of mitochondrial disease is caused by deficiency of coenzyme Q10 (CoQ10), an essential component of the mitochondria involved in energy production. Patients with CoQ10 deficiency often improve dramatically with CoQ10 supplementation. The candidate will study patients with this disease and she will attempt to understand why the mutations cause CoQ10 deficiency. Knowing the cause of CoQ10 deficiency will likely enhance our scientific knowledge of CoQ10 biosynthesis, and will provide molecular tests for accurate genetic counseling, prenatal diagnosis, and more rapid initiation of the therapy.

描述(申请人提供)：辅酶Q10(CoQ10)是一种小的亲脂分子，由苯醌环和疏水的异戊二烯尾巴组成，几乎存在于所有细胞膜中。在线粒体呼吸链中，辅酶Q10在电子从络合物I和络合物II到络合物III的运输中起着至关重要的作用。它还是一种抗氧化剂、膜稳定剂和细胞凋亡的调节剂。人类辅酶Q10缺乏症与四种临床表型有关。所有形式的辅酶Q10缺乏症患者在口服补充剂后都有所改善，因此认识到这种可治疗的遗传疾病是重要的。在过去的十年中，候选人和她的导师收集了84名患者(71个家庭)的生物样本，这些患者患有肌肉和/或成纤维细胞辅酶Q10缺乏症，或根据临床表现和辅酶Q10补充剂的反应怀疑辅酶Q10缺乏症。共有54名患者(48个家庭)记录了肌肉和/或成纤维细胞辅酶Q10缺陷。2006年，研究小组报告了CoQ10生物合成基因的第一个突变，COQ2编码4-对羟基苯甲酸：聚戊烯转移酶；PDSS2编码十碳烯基二磷酸合成酶2亚单位。此外，在一个有四个患有小脑性共济失调和辅酶Q10缺乏症的家庭中，他们发现了aptX基因的一个致病突变，该基因编码一种参与单链断裂修复的蛋白质。因此，这些研究表明辅酶Q10缺乏症可以是原发性的，也可以是继发性的。不足为奇的是，辅酶Q10缺乏会导致呼吸链活性的缺陷(复合体I+III和II+III的活性降低)。呼吸链缺陷、ROS产生和细胞凋亡在辅酶Q10缺乏症发病机制中的相对重要性尚不清楚。研究小组研究了严重CoQ10缺乏对携带COQ2和PDSS2突变的培养皮肤成纤维细胞的生物能量学、氧化应激和抗氧化防御的影响。辅酶Q10生物合成途径前两个关键步骤中的缺陷会产生不同的生化变化。与对照细胞相比，PDSS2突变的成纤维细胞有12%的辅酶Q10，并显著减少了ATP的合成，但没有表现出活性氧物种(ROS)的产生增加，没有氧化应激的迹象，也没有增加抗氧化防御标志。相反，COQ2突变的成纤维细胞有30%的CoQ10存在部分ATP合成缺陷，并显著增加ROS的产生和脂质和蛋白质的氧化。为了更好地了解CoQ10缺乏症的发病机制，研究小组表征了不同程度的CoQ10缺乏症对具有不同CoQ10生物合成遗传缺陷的细胞中ROS产生和线粒体生物能量学的影响。他们证实了他们之前的发现，并进一步观察到CoQ10水平和ROS产生之间的关系遵循抛物线；10-15%的残留CoQ10和60%-70%的CoQ10与显著的ROS产生无关，而30%-50%的残留CoQ10与ROS产生的最大增加有关。此外，活性氧的增加似乎与最初的超极化、随后的去极化和细胞死亡有关。辅酶Q10和其他抗氧化剂对辅酶Q10缺陷患者成纤维细胞的初步治疗结果证实了这些数据。 为了更好地了解人类辅酶Q10缺乏症的发病机制，候选人提出了以下三个具体目标：目的1：确定辅酶Q10缺乏症的新的遗传原因。目的：为了了解同一遗传背景下不同程度辅酶Q10缺乏对线粒体生物能量学和氧化应激的影响，她将利用RNA干扰(RNAi)调控辅酶Q2和PDSS2的表达。目的：通过在COQ2基因突变的成纤维细胞中过表达超氧化物歧化酶(MnSOD)，评估ROS水平、氧化应激和细胞凋亡，以验证清除ROS作为一种潜在的治疗策略的可能性。 叙述：线粒体缺陷会导致多种人类疾病。线粒体疾病的一种亚型是由于辅酶Q10(CoQ10)缺乏引起的，辅酶Q10是参与能量产生的线粒体的基本组成部分。辅酶Q10缺乏症患者补充辅酶Q10后通常会有显著改善。候选人将研究患有这种疾病的患者，她将试图了解为什么这些突变会导致辅酶Q10缺陷。了解辅酶Q10缺陷的原因可能会增强我们对辅酶Q10生物合成的科学知识，并将为准确的遗传咨询、产前诊断和更快地启动治疗提供分子检测。