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）是成人型肌营养不良的最常见原因， 肌肉萎缩症的常见病因强直性肌营养不良1型（DM1）的结果，从扩大 DMPK基因3'非翻译区的CTG重复序列。发病机制的分子基础是一种毒性 从含有长片段扩增的CUG的突变等位基因转录的RNA的功能获得 重复序列（CUGexp RNA）。CUGexp RNA保留在细胞核中，与蛋白质结合形成核糖核蛋白 复合物（RNP）通过RNA荧光原位杂交检测为病灶。CUGexp RNP包括 肌盲样（MBNL）旁系同源物MBNL 1和MBNL 2，被隔离导致其功能丧失 和发病的主要原因。CUGexp RNP是动态的核结构，是导致 DM1发病机制的治疗靶点，但对CUGexp RNP组成的了解有限， 骨骼肌中CUGexp RNA毒性机制的全面解释仍有待建立。到 深入了解骨骼肌中CUGexp RNA和CUGexp RNP的分子和细胞生物学， 此外，我们还将使用邻近标记来鉴定CUGexp RNP复合物的蛋白质和RNA组分 MBNL和CUGexp RNA，并确定其在骨骼肌CUGexp RNA发病机制中的作用。的 结果将为确定新的治疗靶点和提高电流效率提供基础。 靶向RNP的CUGexp RNA组分的方法。

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.