Mammalian iron-sulfur cluster biogenesis

哺乳动物铁硫簇生物发生

• 批准号: 9550385
• 负责人: TRACEY A. ROUAULT
• 金额: $ 85.2万
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9550385
• 关键词: Aconitate Hydratase; Apoproteins; Biogenesis; Biological Markers; Cell Nucleus; Cells; Cessation of life; Citric Acid Cycle; Collaborations; Complex; Cytosol; Data; Disease; Enzymes; FGF21 gene; Ferredoxin; Fibroblasts; Friedreich Ataxia; Genes; Genetic Transcription; Goals; Hereditary Disease; Homeostasis; Infant; Iron; Iron Overload; Iron-Sulfur Proteins; Lactic Acidosis; Mammalian Cell; Mediating; Mitochondria; Mitochondrial Diseases; Molecular Chaperones; Mutagenesis; Mutation; Myopathy; Neonatal; Nuclear; Oxidoreductase; Pathogenesis; Pathway interactions; Patients; Phenotype; Physiological; Problem Solving; Prosthesis; Proteins; RNA Binding; RNA-Binding Proteins; Rare Diseases; Regulation; Respiratory Chain; Respiratory physiology; Role; Scaffolding Protein; Sideroblastic Anemia; Skeletal Muscle; Succinate Dehydrogenase; Sulfur; Sulofenur; Thioctic Acid; Tissues; Work; candidate identification; frataxin; gene product; human disease; iron deficiency; lymphoblast; metabolic abnormality assessment; skeletal muscle metabolism

IRP1 is an iron-sulfur protein related to mitochondrial aconitase, a citric acid cycle enzyme, and it functions as a cytosolic aconitase in cells that are iron replete. Regulation of RNA binding activity of IRP1 involves a transition from a form of IRP1 in which a 4Fe-4S cluster is bound, to a form that loses both iron and aconitase activity. The 4Fe-4S containing protein does not bind IREs. Controlled degradation of the iron-sulfur cluster and mutagenesis reveals that the physiologically relevant form of the RNA binding protein in iron-depleted cells is apoprotein. The status of the cluster appears to determine whether IRP1 will bind RNA. Over the past decade, we have identified mammalian enzymes of iron-sulfur cluster assembly that are homologous to the NifS, ISCU and Nif U, ferredoxin and ferredoxin reductase genes implicated in bacterial iron-sulfur cluster assembly, and we have shown that these gene products facilitate assembly of the iron- sulfur cluster of IRP1. We have discovered that frataxin transcription is iron-dependently regulated and frataxin expression decreases when there is cytosolic iron deficiency in wild-type and in fibroblasts and lymphoblasts from Friedreich ataxia patients. We discovered that a mutation in the scaffold protein, ISCU, causes a rare myopathy. In both Friedreich ataxia and ISCU myopathy, our data indicate that mitochondrial iron overload occurs in conjunction with cytosolic iron depletion. In collaboration, we discovered that NFU1 and BOLA3 mutations cause a human disease characterized by lactic acidosis and lipoic acid deficiency. We predicted that other rare genetic diseases characterized by mitochondrial compromise were caused by mutations in the genes responsible for iron-sulfur cluster biogenesis, and we collaborated to discover that mutations of NFS1 cause neonatal mitochondrial disease. We are characterizing the steps that chaperone transfer of nascent iron-sulfur clusters from their association with the initial assembly apparatus to proteins that require iron-sulfur clusters for function. We have extensively studied the metabolic remodeling of skeletal muscle metabolism in ISCU myopathy and discovered several compensatory pathways that help to maintain energy homeostasis. We have also discovered multiple reasons that limit the phenotype of ISU myopathy to skeletal muscles, while largely sparing other tissues. We are developing antisense treatment therapy for ISCU myopathy, and we recently demonstrated that FGF21 is a good biomarker for muscle disease in ISCU myopathy. We are also actively working to discover how SDHB acquires its three Fe-S clusters, and we have demonstrated that HSC20 cochaperone mediated iron sulfur cluster delivery is critical for iron sulfur acquisition of respiratory chains I-III. We are evaluating many more candidate recipients of iron sulfur clusters, and we expect our studies will greatly increase the number of known mammalian iron sulfur proteins.

IRP 1是一种与线粒体顺乌头酸酶（一种柠檬酸循环酶）相关的铁硫蛋白，它在铁充足的细胞中发挥细胞质顺乌头酸酶的作用。IRP1的RNA结合活性的调节涉及从其中结合4Fe-4S簇的IRP1形式转变为失去铁和顺乌头酸酶活性的形式。含有4Fe-4S的蛋白质不结合IRE。铁-硫簇的受控降解和诱变揭示了铁耗竭细胞中RNA结合蛋白的生理相关形式是脱辅基蛋白。簇的状态似乎决定了IRP1是否会结合RNA。在过去的十年中，我们已经鉴定了与细菌铁-硫簇组装中涉及的NifS、ISCU和Nif U、铁氧还蛋白和铁氧还蛋白还原酶基因同源的铁-硫簇组装的哺乳动物酶，并且我们已经表明这些基因产物促进IRP 1的铁-硫簇的组装。我们已经发现，共济失调蛋白的转录是铁依赖性调节和共济失调蛋白的表达下降时，有野生型和Friedreich共济失调患者的成纤维细胞和淋巴母细胞的胞质铁缺乏。我们发现支架蛋白ISCU的突变导致了一种罕见的肌病。在弗里德赖希共济失调和ISCU肌病，我们的数据表明，线粒体铁超载发生在与细胞溶质铁耗竭。在合作中，我们发现NFU1和BOLA3突变导致一种以乳酸酸中毒和硫辛酸缺乏为特征的人类疾病。我们预测，其他以线粒体受损为特征的罕见遗传疾病是由负责铁硫簇生物发生的基因突变引起的，我们合作发现NFS1突变导致新生儿线粒体疾病。我们正在表征的步骤，伴侣转移新生的铁硫簇从他们的协会与初始组装装置的蛋白质，需要铁硫簇的功能。我们广泛研究了ISCU肌病中骨骼肌代谢的代谢重塑，并发现了几种有助于维持能量稳态的代偿途径。我们还发现了将ISU肌病的表型限制在骨骼肌的多种原因，而在很大程度上保留了其他组织。我们正在开发ISCU肌病的反义治疗疗法，我们最近证明了FGF 21是ISCU肌病肌肉疾病的良好生物标志物。我们还在积极研究SDHB如何获得其三个Fe-S簇，并且我们已经证明HSC 20辅伴侣介导的铁硫簇递送对于呼吸链I-III的铁硫获得至关重要。我们正在评估更多的铁硫簇的候选受体，我们希望我们的研究将大大增加已知哺乳动物铁硫蛋白的数量。