Deciphering the roles of FXR1 in health and myopathy

项目摘要/摘要 RNA结合蛋白影响肌肉功能和疾病进展的机制仍然是 很大程度上是未知的。脆性X相关蛋白1(FXR1)是一种与RNA结合的蛋白，具有多种功能。 调控心肌细胞中RNA的时空表达。越来越明显的是， FXR1是正常肌肉功能所必需的，与人类心脏和骨骼肌病有关。 尽管Fxr1基因在小鼠体内的整体敲除会导致围产期死亡，并伴有心肌和骨骼肌缺陷， 关于FXR1FXR1a的基本机制(S)，人们知之甚少。我们发现FXR1与其他基因相互作用， 转录后调节，编码兴奋-收缩偶联所必需的蛋白质的mRNAs， 包括调节肌球蛋白调节轻链(RLC)磷酸化的成分。我们还确认了 FXR1与编码促性腺激素的信使核糖核酸的相互作用 Duchenne肌营养不良症患者肌营养不良蛋白的缺失我们广泛的初步数据，以及其他人的数据， 显示FXR1蛋白水平在人类DMD心肌细胞和所有DMD模型中显著降低 测试包括来自狗、猪、小鼠和大鼠的那些。值得注意的是，在三种不同的情况下恢复FXR1水平 DMD小鼠模型延缓疾病进展，导致结构和功能的改善 包括心肌和骨骼肌。DMD小鼠的中性粒细胞营养素表达也增加 FXR1水平。因此，我们假设FXR1特定地调节细胞成分，这些细胞成分对 适当的肌肉功能和FXR1水平/功能的改变有助于疾病的进展，尤其是在 DMD。我们提出了一种从单分子到活体研究的全球、公正和多学科的方法， 包括使用人体组织，使我们能够实现三个具体目标，重点是确定 脆性X蛋白的基本生理功能及其在肌肉发病机制中的作用。此外，我们 将是首批评估预防DMD大鼠肌肉功能障碍的基因治疗策略的小组之一(a 与人类DMD非常相似的模型)。我们预测这些发现将促进一种独特的核糖核酸水平 改善肌肉疾病进展的治疗方法。

PROJECT SUMMARY/ABSTRACT The mechanism whereby RNA-binding proteins impact muscle function and disease progression is still largely unknown. Fragile X-related protein 1 (FXR1), an RNA-binding protein, is multi-functional and plays a role in regulating the temporal and spatial expression of RNAs in myocytes. It is becoming increasingly evident that FXR1 is essential for normal muscle function and is associated with both human cardiac and skeletal myopathies. Although global knockout of Fxr1 in mice results in perinatal lethality with cardiac and skeletal muscle defects, little is known regarding the fundamental mechanistic role(s) of FXR1. We discovered that FXR1 interacts with, and post-transcriptionally regulates, mRNAs that encode proteins essential for excitation-contraction coupling, including components that regulate phosphorylation of the myosin regulatory light chain (RLC). We also identified an interaction between FXR1 and the mRNA that encodes utrophin, a protein that can functionally substitute for the loss of dystrophin in Duchenne Muscular Dystrophy. Our extensive preliminary data, and data from others, reveal that FXR1 protein levels are significantly reduced in human DMD myocytes as well as in all DMD models tested including those from canine, pig, mouse and rat. Remarkably, restoring FXR1 levels in three different mouse models of DMD attenuates disease progression, resulting in structural and functional improvements in both cardiac and skeletal muscle. Utrophin expression is also enhanced in DMD mice in response to increased FXR1 levels. Thus, we hypothesize that FXR1 specifically regulates cellular components that are critical for proper muscle function and alterations in FXR1 levels/function contribute to disease progression, particularly in DMD. We propose a global, unbiased and multidisciplinary approach from single molecule to in vivo studies, including the use of human tissue, to allow us to accomplish three Specific Aims focused on determining the basic physiological function of a Fragile X protein and the role it plays in muscle pathogenesis. In addition, we will be among the first groups to assess gene-therapy strategies to prevent muscle dysfunction in DMD-rats (a model which closely resembles human DMD). We predict these discoveries will facilitate a unique RNA-level therapeutic approach to ameliorate muscle disease progression.