Inducible Transgenic Mouse Model of RNA Toxicity

描述（由申请人提供）：强直性肌营养不良（DM）是成人中最常见的遗传性神经肌肉疾病。有两种类型，DM 1和DM 2，两者都是由其各自基因的非编码区内的微卫星重复序列扩增引起的常染色体显性遗传病。DM 1更为常见;然而，这两种形式的DM可能具有相似的致病机制。DM 1突变是DM蛋白激酶（DMPK）基因3'非翻译区（3' UTR）中CTG三联体重复序列的扩增。该领域的流行假设是DM的许多方面是由突变mRNA的表达引起的。DM 1和DM 2代表了毒性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，以清楚地证明突变体DMPK mRNA对肌肉分化的毒性作用。为了进一步研究这一假设，本提案的目的是开发和表征DM 1型（DM 1）的RNA毒性的诱导型转基因小鼠模型，并开发siRNA（小干扰RNA）治疗方法以去除毒性RNA，该方法可以在我们的细胞培养物和转基因动物模型中进行测试。 转基因小鼠模型的发展将有助于理解疾病的发病机制，也将提供一个系统，以测试出潜在的治疗策略。通过诱导型系统控制基因表达的能力将能够更好地表征DM 1中毒性RNA的表达的开始和水平以及疾病结果，并与之更好地相关。最重要的是，由于这种特性，该模型将是我们可以在整个生物体水平上直接测试的第一个模型之一，如果在暴露一段时间后消除有毒RNA的表达可以逆转其毒性作用。所有糖尿病患者从出生起就一直暴露于有毒的RNA，因此像这样的模型将能够为这种治疗策略提供有价值的和相关的见解。

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.