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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.

弗里德赖希共济失调症（FRDA）是一种常染色体隐性神经退行性疾病