Post-transcriptional Regulation of Gene Expression in Neuromuscular Disease

描述（由申请人提供）：强直性肌营养不良（DM）是肌营养不良的最常见形式，并导致所有肌肉类型的症状，表现为骨骼肌萎缩、心律失常和胃肠道功能障碍。糖尿病是一种多系统疾病，通常也会影响中枢神经、内分泌和生殖系统。DM是由扩增的CTG或CCTG重复序列引起的，其被转录成RNA，隔离肌盲样（MBNL）RNA结合蛋白并滴定它们远离其正常mRNA靶。CUG重复表达还导致CUGBP/ELAV样因子（CELF）的过度磷酸化，导致CELF蛋白升高。MBNL和CELF的失调导致转录组的数百种变化，包括可变剪接中的许多变化。到目前为止，DM中转录组变化的全谱仍然没有表征，并且尚不清楚MBNL和CELF扰动是否可以完全解释这些变化。此外，仅发现了少数DM症状的分子原因。由MBNL蛋白介导的另一个细胞过程是RNA定位。RNA的亚细胞定位对于许多细胞和生理过程是重要的，包括细胞运动、胚胎模式和突触功能。然而，我们对RNA定位的理解仍然局限于转录本的一小部分，并且我们缺乏RNA定位如何实现的分子部分列表。识别这些参与者将揭示RNA错误定位对DM和其他疾病病理学的影响程度。因此，我们将系统地表征DM中的转录组变化，并评估MBNL和CELF扰动可以解释DM转录组中这些变化的程度（目的1）。我们将定义RNA定位的部分列表，包括顺式和反式元件，并阐明这些参与者如何控制RNA的亚细胞分布（目标2）。我们将研究基因表达的所有步骤的变化，包括剪接，RNA定位和翻译，可能与DM表型相关，并开发治疗方法来纠正这些变化（目标3）。总之，这项工作的完成将进一步加深我们对DM分子变化的理解，DM是RNA毒性疾病的范例，为更好地理解RNA定位奠定了基础，并有助于将这些分子事件与生理学联系起来。

DESCRIPTION (provided by applicant): Myotonic dystrophy (DM) is the most common form of muscular dystrophy, and leads to symptoms in all muscle types, in the form of skeletal muscle wasting, cardiac arrhythmias, and gastrointestinal dysfunction. A multi-systemic disease, DM also commonly affects the central nervous, endocrine, and reproductive systems. DM is caused by expanded CTG or CCTG repeats, which are transcribed into RNA, sequestering the Muscleblind- like (MBNL) RNA binding proteins and titrating them away from their normal mRNA targets. CUG repeat expression also leads to hyper-phosphorylation of the CUGBP/ ELAV-like factors (CELFs), resulting in CELF protein elevation. Dysregulation of MBNLs and CELFs causes hundreds of changes to the transcriptome, including many changes in alternative splicing. To date, the full spectrum of transcriptome changes in DM remains uncharacterized, and it is unknown whether MBNL and CELF perturbation can fully account for those changes. Furthermore, the molecular causes of only a few DM symptoms have been discovered. Another cellular process mediated by the MBNL proteins is RNA localization. Subcellular localization of RNA is important for numerous cellular and physiological processes, including cell motility, embryonic patterning, and synaptic function. However, our understanding of RNA localization remains restricted to a small subset of transcripts, and we lack a molecular parts list for how RNA localization is achieved. Identification of these players will reveal the extent to which RNA mis-localization contributes to pathology in DM and other diseases. Therefore, we will systematically characterize transcriptome changes in DM and assess the extent to which MBNL and CELF per- turbation can explain these changes in DM transcriptomes (Aim 1). We will define a parts list for RNA localization, including cis- and trans- elements, and elucidate how these players control subcellular distribution of RNAs (Aim 2). We will study how changes in all steps of gene expression, including splicing, RNA localization, and translation, may be linked to DM phenotypes, and develop therapeutic approaches to correct these changes (Aim 3). Together, completion of this work will further our understanding of the molecular changes in DM, a paradigm for diseases of RNA toxicity, lay the groundwork for better understanding RNA localization, and help connect these molecular events to physiology.