MOUSE MUSCLEBLIND MODEL FOR MYOTONIC DYSTROPHY

强直性肌营养不良小鼠肌盲模型

• 批准号: 6824697
• 负责人: MAURICE SCOTT SWANSON
• 金额: $ 29.83万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6824697
• 关键词: RNA splicing; adeno associated virus group; chloride channels; cooperative study; disease /disorder model; gene deletion mutation; gene expression; genetically modified animals; laboratory mouse; model design /development; molecular pathology; muscle proteins; myogenesis; myotonic dystrophy; phenotype; recombinant proteins; recombinant virus

The myotonic dystrophies (DM1 and DM2), which are the most common form of adult-onset muscular dystrophy, are autosomal dominant diseases with similar clinical presentations. Remarkably, DM1 and DM2 are caused by unstable microsatellite expansions in the untranslated regions of two different genes, DMPK and ZNF9. To explain how these non-coding expansion mutations lead to dominantly inherited neuromuscular disorders, we have proposed a toxic RNA model for the myotonic dystrophies. Transcription of the mutant DM1 (CTG)n and DM2 (CCTG)n alleles leads to the production of unusual RNA transcripts with (CUG)n and (CCUG)n repeat expansions. These expansions fold into stable double-stranded (ds) RNA structures that recruit and then sequester a family of dsRNA-binding factors, the muscleblind proteins. Because this toxic RNA model suggests that DM1 and DM2 diseases are due to loss of muscleblind protein function, we have derived muscleblind 1 (Mbnl1) knockout mice. This proposal is designed to test our working hypothesis that Mbnl1-/- knockout mice will be a useful model to examine underlying molecular mechanisms involved in myotonic dystrophy disease pathogenesis. First, we will characterize the Mbnl1-/-muscle phenotype and test the hypothesis that Mbnl1 is required for proper alternative splicing and function of the chloride channel CIC-1. Deficiency of this ion channel has been recently implicated as the cause of DM1- and DM2- associated myotonia. The stoichiometric relationship between toxic RNA and binding protein will be examined by breeding Mbnll knockout mice with lines of transgenic mice that express (CUG)n RNA at different levels. Second, the possibility that muscleblind proteins influence CIC-1 chloride channel levels by interacting with alternative splicing, and/or other, factors will be examined. Third, the hypothesis that the myotonia phenotype can berescued using recombinant adeno-associated virus mediated expression of wild type adult CIC-1 will be tested. Finally, we will investigate if additional disease-associated phenotypes result from deletion of the entire Mbnl1 gene, from tissue-specific Mbnl1 expression or from combinatorial loss of all three muscleblind (Mbnl1, Mbnl2/Mbnll, Mbnl3/Mblx) genes.

肌发育症（DM1和DM2）是成人发作肌肉营养不良的最常见形式，是常染色体显性疾病，具有相似的临床表现。值得注意的是，DM1和DM2是由两个不同基因DMPK和ZnF9的非翻译区域中不稳定的微卫星扩张引起的。为了解释这些非编码膨胀突变如何导致主要遗传的神经肌肉疾病，我们提出了一个有毒的RNA模型，用于肌发育症。突变体DM1（CTG）N和DM2（CCTG）N等位基因的转录导致具有（CUG）N和（CCUG）N重复扩展的异常RNA转录物的产生。这些膨胀折叠成稳定的双链（DS）RNA结构，这些结构募集，然后隔离一个DSRNA结合因子，即肌肉蓝线蛋白。因为这种有毒的RNA模型表明DM1和DM2疾病是由于肌肉盲蛋白的损失引起的 功能，我们衍生了肌肉盲1（MBNL1）敲除小鼠。该建议旨在检验我们的工作假设，即MBNL1 - / - 基因敲除小鼠将是一个有用的模型，用于检查涉及肌发育症疾病发病机理的潜在分子机制。首先，我们将表征MBNL1 - / - 肌肉表型，并检验以下假设：MBNL1是氯化物通道CIC-1的适当替代剪接和功能所必需的。该离子通道的不足最近被认为是DM1和DM2-相关肌张力的原因。有毒RNA与结合蛋白之间的化学计量关系将通过与在不同水平上表达（CUG）n RNA的转基因小鼠品系繁殖MBNLL敲除小鼠进行检查。其次，将检查肌肉盲蛋白通过与替代剪接和/或其他因素相互作用而影响CIC-1氯化物通道水平的可能性。第三， 假设将测试使用重组腺相关病毒介导的野生型成人CIC-1表达的肌瘤表型。最后，我们将调查是否是由于整个MBNL1基因的删除，组织特异性MBNL1表达或所有三个肌肉斜线的组合丧失（MBNL1，MBNL2/MBNLL，MBNL3/MBLX）基因是否引起的其他相关表型。