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 强直性肌营养不良症是第二个最常见的原因，肌营养不良症和最常见的原因 成人型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。该项目的长期目标是确定导致骨骼肌损伤的机制。 1型强直性肌营养不良（DM 1）的肌肉发病机制。DM 1是一种常染色体显性遗传疾病， 在DMPK基因的3'非翻译区中的CTG重复扩增。这种疾病的分子基础 是转录的含有扩展的CUG重复序列（CUGexp RNA）的RNA功能的毒性获得 来自突变等位基因。CUGexp RNA在核RNA灶中积累并导致细胞功能丧失 肌盲样（MBNL）RNA结合蛋白，在核灶内的CUGexp RNA上被隔离。 CUGexp RNA还诱导CELF 1蛋白的上调，该蛋白已被证明对骨骼肌有毒性。 肌肉. MBNL和CELF 1蛋白调节大量基因的选择性剪接转换， 骨骼肌出生后发育。它们在DM 1骨骼肌中的功能改变导致失调 选择性剪接和不适当的表达胎儿蛋白异构体在成人骨骼肌，导致 疾病特征。虽然已经建立了MBNL功能丧失的基础，但引起MBNL功能丧失的机制仍然存在。 骨骼肌中的CELF 1上调是未知的。我们发现Mbnl 1/Mbnl 2双敲除在成人中， 小鼠骨骼肌导致CELF 1蛋白上调，表明MBNL与 功能丧失和CELF 1活性增加。我们还建立了DM 1的转基因小鼠模型， 其中含有扩增的CUG重复序列的人DMPK mRNA的骨骼肌特异性表达 复制DM 1特征，包括CELF 1上调。本提案的目标是确定 Mbnl 1/Mbnl 2双敲除和表达对CELF 1上调的分子机制 并确定CELF 1上调对骨骼肌的贡献 由MBNL功能丧失和CUGexp RNA引起的发病机制。