Identification of components and mechanisms regulating expanded CUG-repeat RNP complexes in Myotonic Dystrophy Type 1 muscle cells

项目摘要 强直性肌营养不良(DM)是成人肌营养不良最常见的原因，也是第二大原因 总体上是肌肉营养不良的常见原因。强直性肌营养不良1型(DM1)由扩张型 DMPK基因3‘端非翻译区CTG重复序列。致病的分子基础是有毒的 从含有长片段扩展的CUG的突变等位基因转录的RNA的功能获得 重复(CUGexp RNA)。CUGexp RNA残留在细胞核内，与蛋白质结合形成核糖核蛋白 RNA荧光原位杂交检测为病灶的复合体(RNPs)。CUGexp RNP包括 类粘虫(MBNL)类副犬，MBNL1和MBNL2，被隔离，导致其功能丧失 也是致病的主要原因。CUGexp RNP是动态的核结构，是原因和 DM1发病机制的治疗靶点目前对CUGexp RNP的组成了解有限 CUGexp RNA对骨骼肌的毒性机制仍有待确定。至 深入了解骨骼肌中CUGexp RNA和CUGexp RNP的分子和细胞生物学， 此外，我们将使用邻近标记来识别CUGexp RNP复合体的蛋白质和RNA成分 MBNL和CUGexp RNA，并确定它们在骨骼肌CUGexp RNA发病机制中的作用。这个 研究结果将为寻找新的治疗靶点和提高电流的效率提供基础 针对RNP的CUGexp RNA组件的方法。

Project Summary Myotonic dystrophy (DM) is the most common cause of adult-onset muscular dystrophy and the second most common cause of muscular dystrophy overall. Myotonic dystrophy type 1 (DM1) results from an expanded CTG repeat in the 3’ untranslated region of the DMPK gene. The molecular basis for pathogenesis is a toxic gain of function of the RNA transcribed from the mutant allele that contains long tracts of expanded CUG repeats (CUGexp RNA). CUGexp RNA remains in the nucleus bound with proteins to form ribonucleoprotein complexes (RNPs) detected as foci by RNA fluorescence in situ hybridization. CUGexp RNPs include the Muscleblind-Like (MBNL) paralogs, MBNL1 and MBNL2, that are sequestered resulting in their loss of function and a primary cause of pathogenesis. CUGexp RNPs are dynamic nuclear structures that are the cause and therapeutic target of DM1 pathogenesis yet knowledge of the composition of the CUGexp RNP is limited and a full accounting of the mechanisms of CUGexp RNA toxicity in skeletal muscle remains to be established. To gain insight into the molecular and cellular biology of CUGexp RNA and the CUGexp RNP in skeletal muscle, we will use proximity labeling to identify protein and RNA components of the CUGexp RNP complex in addition to MBNL and CUGexp RNA and determine their roles in CUGexp RNA pathogenesis in skeletal muscle. The results will provide the foundation to identify novel therapeutic targets and enhance the efficiency of current approaches targeting the CUGexp RNA component of the RNP.