Inducible Transgenic Mouse Model of RNA Toxicity

描述（由申请人提供）：肌强直性营养不良症（DM）是成人中最常见的遗传性神经肌肉疾病。有两种类型，DM1和DM2，都是常染色体显性疾病，由各自基因的非编码区域内微卫星重复扩增引起。DM1更为常见；然而，两种形式的糖尿病可能具有相似的致病机制。DM1突变是DM蛋白激酶（DMPK）基因3‘非翻译区（3’ utr）的CTG三重重复扩增。该领域的一个普遍假设是，糖尿病的许多方面是由突变mRNA的表达引起的。DM1和DM2是毒性RNA介导的疾病发病机制的第一个例子。我们已经开发并广泛表征了成肌细胞培养模型，以清楚地证明突变DMPK mRNA对肌肉分化的毒性作用。为了进一步研究这一假设，本提案的目的是建立和表征一种可诱导的转基因小鼠DM1型（DM1） RNA毒性模型，并开发一种siRNA（小干扰RNA）治疗方法来去除有毒RNA，该方法可以在我们的细胞培养和转基因动物模型中进行测试。

DESCRIPTION (provided by applicant): Myotonic dystrophy (DM) is the most common inherited neuromuscular disorder in adults. There are two types, DM1 and DM2, both being autosomal dominant disorders caused by expansions of microsatellite repeats within non-coding regions of their respective genes. DM1 is far more common; however both forms of DM are likely to share similar pathogenic mechanisms. The DM1 mutation is an expansion of a CTG triplet repeat in the 3' untranslated region (3'UTR) of the DM protein kinase (DMPK) gene. A prevailing hypothesis in the field is that many aspects of DM are caused by the expression of the mutant mRNA. DM1 and DM2 represent the first examples of toxic RNA mediated disease pathogenesis. We have already developed and characterized extensively, a myoblast cell culture model to clearly demonstrate the toxic effects of the mutant DMPK mRNA on muscle differentiation. To study the hypothesis further, the aims of this proposal are to develop and characterize an inducible transgenic mouse model of RNA toxicity for DM type 1 (DM1) and to develop a siRNA (small interfering RNA) therapeutic approach to get rid of the toxic RNA which can be tested in both our cell culture and transgenic animal models. The development of transgenic mouse models will aid in understanding disease pathogenesis and will also provide a system with which to test out potential therapeutic .strategies. The ability to control gene expression through an inducible system will enable better characterization of and better correlation with the onset and levels of expression of the toxic RNA in DM1 and disease outcomes. Most importantly, because of this property, this model will be one of the first in which we can directly test, at the level of a whole organism, if ablation of expression of the toxic RNA after a period of exposure can reverse its toxic effects. All DM patients have endured exposure to the toxic RNA from birth and thus a model such as this one will be able to provide valuable and relevant insight into this therapeutic strategy.