Mechanisms of Skeletal Muscle Pathogenesis in Myotonic Dystrophy Type 1

1 型强直性肌营养不良的骨骼肌发病机制

• 批准号: 10716746
• 负责人: Thomas A Cooper
• 金额: $ 54.35万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-06 至 2028-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10716746
• 关键词: 3' Untranslated Regions; Adult; Affect; Alleles; Alternative Splicing; Blood specimen; CUG repeat; Characteristics; Clinical; Disease; Disease Progression; Embryo; Etiology; Exons; Family; Family member; Fetal Proteins; Foundations; Frequencies; Genes; Genetic; Genetic Transcription; Goals; Histopathology; Human; In Vitro; Individual; Knock-out; Link; LoxP-flanked allele; Messenger RNA; Modeling; Molecular; Mus; Muscle; Muscular Atrophy; Muscular Dystrophies; Mutation; Myopathy; Myotonic Dystrophy; Myotonic dystrophy type 1; Natural regeneration; Newborn Infant; Nuclear; Nuclear RNA; Pathogenesis; Pathogenicity; Pathology; Pattern; Phenotype; Physiological; Play; Prevalence Study; Protein Isoforms; Proteins; RNA; RNA Processing; RNA Splicing; RNA-Binding Proteins; Regulation; Role; Severity of illness; Skeletal Muscle; System; Tissues; Toxic effect; Transgenic Mice; Translations; United States; Up-Regulation; Work; autosome; combinatorial; gain of function; in vivo; knock-down; loss of function; mRNA Translation; mortality; mouse model; mutant; postnatal development; response; skeletal muscle weakness; small hairpin RNA; targeted treatment; wasting

Project Summary Myotonic dystrophy is the second most common cause of muscular dystrophy and the most common cause of adult onset muscular dystrophy. The primary cause of disease mortality is progressive skeletal muscle weakness and wasting. The long term goal of this project is to determine the mechanisms that cause skeletal muscle pathogenesis in myotonic dystrophy type 1 (DM1). DM1 is an autosomal dominant disease caused by a CTG repeat expansion in the 3’ untranslated region of the DMPK gene. The molecular basis for the disease is a toxic gain of function of the RNA containing expanded CUG repeats (CUGexp RNA) that is transcribed from the mutant allele. CUGexp RNA accumulates in nuclear RNA foci and causes loss of function of Muscleblind like (MBNL) RNA binding proteins that are sequestered on CUGexp RNA within the nuclear foci. CUGexp RNA also induces upregulation of CELF1 protein that has been shown to be toxic to skeletal muscle. MBNL and CELF1 proteins regulate alternative splicing transitions of a large number of genes during skeletal muscle postnatal development. Their altered functions in DM1 skeletal muscle causes misregulated alternative splicing and inappropriate expression of fetal protein isoforms in adult skeletal muscle that leads to disease features. While the basis for MBNL loss of function has been established, the mechanisms causing CELF1 upregulation in skeletal muscle are unknown. We find that Mbnl1/Mbnl2 double knockout in adult mouse skeletal muscle results in CELF1 protein upregulation, indicating a mechanistic link between MBNL loss of function and increased CELF1 activity. We also established a transgenic mouse model for DM1 in which skeletal muscle specific expression of a human DMPK mRNA containing expanded CUG repeats reproduces DM1 features including CELF1 upregulation. The goals of this proposal are to determine the molecular mechanisms of CELF1 upregulation in response to Mbnl1/Mbnl2 double knockout and expression of the toxic CUGexp RNA and to determine the contributions of CELF1 upregulation to skeletal muscle pathogenesis caused by MBNL loss of function and CUGexp RNA.

项目摘要 强直性肌营养不良是肌营养不良的第二大常见原因，也是最常见的原因 成人起病的肌营养不良症。疾病死亡的主要原因是进行性骨骼肌 软弱和浪费。这个项目的长期目标是确定导致骨骼的机制 强直性肌营养不良1型(DM1)的肌肉发病机制。DM1是一种常染色体显性遗传病，由 DMPK基因3‘端非翻译区CTG重复序列扩增。该病的分子基础 是含有被转录的扩展CUG重复序列的RNA(CUGexp RNA)的有毒功能获得 来自突变的等位基因。CUGexp RNA聚集在核RNA焦点并导致功能丧失 粘虫样(MBNL)RNA结合蛋白，隔离在核病灶内的CUGexp RNA上。 CUGexp RNA还可诱导CELF1蛋白上调，该蛋白已被证明对骨骼有害 肌肉。MBNL和CELF1蛋白调节大量基因的选择性剪接过渡 骨骼肌生后发育。它们在DM1骨骼肌中的功能变化导致调节失调 成人骨骼肌中胎儿蛋白亚型的选择性剪接和不适当表达导致 疾病特征。虽然MBNL功能丧失的基础已经确立，但导致MBNL功能丧失的机制 CELF1在骨骼肌中的上调是未知的。在成人中发现MBNL1/MbnL2双基因敲除 小鼠骨骼肌导致CELF1蛋白上调，表明MBNL之间存在机械联系 功能丧失，CELF1活性升高。我们还建立了DM1的转基因小鼠模型 含有扩增的CUG重复序列的人DMPK基因在骨骼肌中的特异性表达 复制DM1功能，包括CELF1上调。这项提案的目标是确定 MBNL1/Mbnl2双基因敲除和表达上调CELF1的分子机制 毒性CUGexp RNA的表达以及CELF1上调对骨骼肌的作用 发病机制由MBNL功能丧失和CUGexp RNA引起。