Defining the impact of Frataxin point mutations on Friedreich's ataxia pathogenesis

确定 Frataxin 点突变对 Friedreich 共济失调发病机制的影响

基本信息

批准号：
10181593
负责人：
Marek Napierala
金额：
$ 37.13万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-03-01 至 2021-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10181593
关键词：
Address Affect Afferent Neurons Alleles Amino Acids Anabolism Ataxia Axonal Transport Binding Biochemical Biophysics Cell model Cell physiology Cells Characteristics Clinical Complex Data Disease Disease Progression Electron Microscopy Enzymes Exhibits Friedreich Ataxia Genes Genotype Glycine Hereditary Spastic Paraplegia Heterozygote Impairment In Vitro Introns Iron Knowledge Link Lower Extremity Mediating Missense Mutation Mitochondria Mitochondrial Matrix Mitochondrial Proteins Modeling Molecular Molecular Chaperones Molecular Sieve Chromatography Mutation NMR Spectroscopy Neurodegenerative Disorders Neurons Nonsense Mutation Pathogenesis Pathogenicity Pathologic Pathway interactions Patients Peptide Hydrolases Phenotype Point Mutation Positioning Attribute Production Property Protein Isoforms Proteins Reagent Respiration Sampling Sensory Severities Speech Structure Sulfur Symptoms Testing Therapeutic Translating Trinucleotide Repeats Upper Extremity Valine Work axonal degeneration base design experience experimental study frataxin induced pluripotent stem cell lipid metabolism mouse model multiple myeloma M Protein mutant novel patient subsets preservation response spasticity therapy development

项目摘要

Friedreich’s ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by reduced expression of the mitochondrial protein frataxin (FXN). Frataxin is translated as a 210 amino acid (aa) precursor (FXN-P) that is imported into the mitochondrial matrix where it undergoes sequential cleavage steps, producing a 168 aa intermediate (FXN-I) and the mature isoform of 129 aa (FXN-M). Frataxin participates in iron-sulfur cluster (ISC) biosynthesis in the mitochondria, and many of the overt FRDA phenotypes result from deficient activity of ISC- containing enzymes. Currently, there is no cure for this debilitating disease. Most FRDA patients are homozygous for large expansions of GAA triplet repeat sequences in intron 1 of the FXN gene, while a subset of patients are compound heterozygotes with an expanded GAA repeat tract in one FXN allele and a missense or nonsense mutation in the other. Homozygous and compound heterozygous mutant genotypes both result in reduced levels of FXN-M protein when compared with healthy controls. The most prevalent missense mutation changes a glycine to valine at position 130 (G130V). FRDA G130V patients exhibit different clinical features than patients harboring homozygous GAA expansions, including lower limb spasticity rather than ataxia, preserved sensory responses, spared speech and upper limb functions, and slower disease progression. Paradoxically, substantially less FXN-M protein is detectable in G130V patient samples than in patient samples harboring two expanded alleles. Our preliminary data revealed that normal mitochondrial maturation processing of the FXN protein is perturbed by the G130V mutation, suggesting functional importance of an intermediate isoform (G130V-I). We hypothesize that the G130V mutation impairs FXN mitochondrial maturation processing and/or destabilizes the mature isoform. The unprocessed FXN-G130V-I isoform is functional and partially compensates for the substantial reduction of FXN-M, thus slowing disease progression and contributing to the distinct symptoms of FRDA G130V patients. To address these hypotheses, we will use novel cellular and mouse models of FRDA G130V. First, we will define the structural and functional properties of the FXN-G130V-I isoform to test whether this mutation confers a change of function that contributes to the atypical clinical presentation of FRDA G130V patients. Subsequently, we will determine mechanisms governing steady state levels and maturation processing of FXN-G130V in iPSC-derived cortical and sensory neurons. Finally, using FRDA patient-derived neuronal models as well as our novel Fxn G127V mouse model, we will define molecular mechanisms underlying the unique clinical presentation of FRDA G130V patients. Results of the proposed studies will have a broad impact on therapy development for all FRDA patients.

Friedreich的共济失调（FRDA）是一种由表达降低引起的常染色体隐性神经退行性疾病线粒体蛋白Frataxin（FXN）的Frataxin被翻译为210氨基酸（AA）前体（FXN-P）该导入到线粒体矩阵中，在该基质中进行顺序裂解步骤，产生168 AA 中间体（FXN-I）和129 AA（FXN-M）的成熟亚型。铁硫簇（ISC）的Frataxin参与者线粒体中的生物合成，许多明显的FRDA表型是由于ISC的不足而导致的含有酶。目前，这种使这种使人衰弱的疾病无法治愈。大多数FRDA患者是 FXN基因内含子1中GAA三重序列的大量扩展的纯合子，而子集患者是一个复合杂合子，在一个FXN等位基因中具有扩展的GAA重复道和错过或另一个无意义的突变。纯合和复合杂合突变基因型都导致与健康对照相比，FXN-M蛋白水平降低。最普遍的错义突变在130（G130V）位置将甘氨酸更改为Valine。 FRDA G130V患者暴露了不同的临床特征保留了具有纯合GAA扩展的患者，包括下肢痉挛而不是共济失调的患者感觉反应，遗憾的语音和上肢功能以及疾病进展缓慢。矛盾的是，在G130V患者样品中可检测到的FXN-M蛋白要比有两个的患者样本中检测到的FXN-M蛋白要少得多。扩展的等位基因。我们的初步数据表明，FXN的正常线粒体成熟处理蛋白质受到G130V突变的干扰，表明中间同工型的功能重要性（g130v-i）。我们假设G130V突变会损害FXN线粒体成熟处理和/或破坏成熟的同工型。未加工的FXN-G130V-I同工型具有功能性，部分补偿为了大大减少FXN-M，因此疾病的进展减慢并有助于不同 FRDA G130V患者的症状。为了解决这些假设，我们将使用新型的细胞和小鼠模型 FRDA G130V。首先，我们将定义FXN-G130V-I同工型的结构和功能特性这种突变是否承认有助于FRDA非典型临床表现的功能变化 G130V患者。随后，我们将确定控制稳态水平和成熟的机制在IPSC衍生的皮质和感觉神经元中FXN-G130V的处理。最后，使用FRDA患者来源神经元模型以及我们的新型FXN G127V小鼠模型，我们将定义分子机制 FRDA G130V患者的独特临床表现。拟议研究的结果将有广泛的对所有FRDA患者的治疗发展的影响。