Transcriptome processing networks in skeletal muscle: mechanisms and functions

项目摘要 该项目的长期目标是确定范围、监管机制和功能 骨骼肌中受调节的前mRNA加工的后果。大量的基因表达前- mRNA通过选择性剪接产生保守的肌肉特异性蛋白质亚型， 其中，未知数。这些亚型通常出现在胎儿晚期或出生后早期发育期间。中断 选择性剪接是影响骨骼肌的疾病的共同特征，通常涉及到 胎儿亚型，但很少有人知道这些变化的发病机制的贡献。下面的 该建议的假设是，关注具有保守的胎儿和成人蛋白质同种型的基因，包括 肌肉特异性的成人亚型不仅会发现以前未知的亚型特异性功能， 也是以前未知的对成人肌肉稳态至关重要的基因功能。确定的功能 在体内的选择性剪接事件中，我们使用CRISPR介导的外显子去除， 具体和/或出生后规定的纳入。在第一个目标中，我们将确定一个条纹的功能， Map 4微管结合蛋白的肌肉特异性同种型，其中肌肉特异性外显子的缺失 显著破坏骨骼肌肌纤维中的微管结构并影响肌力 一代在第二个目标中，我们将确定骨骼肌特异性Limch 1同种型的功能， 其缺乏也降低体内骨骼肌功能。在第三个目标中，我们将使用CRISPR- 介导的表位标签引入内源性基因，以监测内源性基因表达的时间和空间细节。 选择性剪接转换和成人肌肉特异性异构体在体内单个细胞水平。这 这项研究有望确定以前未知的基因功能，增加对成人骨骼肌的了解， 肌肉稳态及其破坏对疾病的影响。

Project Summary The long-term goal of this project is to determine the extent, regulatory mechanisms, and functional consequences of regulated pre-mRNA processing in skeletal muscle. A large number of genes express pre- mRNAs that undergo alternative splicing to produce conserved muscle-specific protein isoforms the functions of which are unknown. These isoforms often appear during late fetal or early postnatal development. Disruption of alternative splicing is a common feature of diseases affecting skeletal muscle, often involving reversion to fetal isoforms, yet little is known about the contributions of these changes to pathogenesis. An underlying hypothesis of this proposal is that a focus on genes with conserved fetal and adult protein isoforms, including adult isoforms that are muscle-specific, will discover not only previously unknown isoform-specific functions but also previously unknown gene functions critical for adult muscle homeostasis. To identify the functions of alternative splicing events in vivo we are using CRISPR-mediated removal of exons that undergo muscle- specific and/or postnatally regulated inclusion. In the first aim, we will determine the functions of a striated muscle-specific isoform of the Map4 microtubule-binding protein in which deletion of the muscle-specific exon significantly disrupts microtubule architecture in skeletal muscle myofibers and impacts muscle force generation. In the second aim we will determine the function of the skeletal muscle-specific Limch1 isoform, the absence of which also decreases skeletal muscle function in vivo. In the third aim we will use CRISPR- mediated introduction of epitope tags into endogenous genes to monitor the temporal and spatial details of the alternative splicing transitions and adult muscle-specific isoforms at the level of individual cells in vivo. This study is expected to identify previously unknown gene functions, increase understanding of adult skeletal muscle homeostasis and the impact of its disruption in disease.