Delineating the Function of TDP-43 in Skeletal Muscle Formation

项目摘要/总结 许多退行性神经肌肉疾病与细胞质中蛋白质的积累有关 集料.这些聚集体被广泛认为是导致疾病的原因，因此被认为对人类是有毒的。 cell.最近，我们发现了类似的聚集体，称为肌颗粒，在健康的再生和 分化骨骼肌。肌粒含有RNA和RNA结合蛋白。一个突出的RNA- 在肌颗粒中发现的结合蛋白TDP-43由于其在聚集体中的存在而特别令人感兴趣 在退行性疾病中观察到。此外，肌颗粒定位于发育中的肌节， 携带TDP-43结合位点的肌节mRNA的丰度。随着肌肉再生和肌节 被替换，肌颗粒被清除，TDP-43重新定位到细胞核。总之，这些发现表明 TDP-43可能在促进肌节形成和含TDP-43的细胞聚集中起作用， 在疾病中发现的聚集物可能不是原因，而是反复尝试骨骼移植的结果。 再生在前期工作中，我发现肌肉干细胞中的TDP-43缺失会阻止分化， 确定TDP-43在骨骼肌中的重要作用。具体目标1将评估TDP-43在以下方面的作用： 再生过程中肌纤维的形成和成熟。为此，我将删除TDP-43， 用于分化细胞的融合和用于再生肌肉的成熟的再生检查点。的 目标1的结果将用于具体目标2的实验，在那里我将分析TDP的作用- 肌节形成43例。在前期工作中，TDP-43在分化细胞再生过程中的缺失 导致肌肉被不适当地修复并且肌纤维尺寸急剧减小。此外，肌纤维 当TDP-43缺失时，成熟减少，如发育相关基因的持续表达所示。 肌节蛋白因此，TDP-43是肌节再生和修复所必需的吗？我会问这个问题 通过采用体内方法，其中TDP-43将在健康和再生肌肉中缺失， 评价对肌节形成、成熟和降解的影响。TDP-43的功能概述 在肌节形成中的作用将使我们更好地理解肌颗粒和 疾病相关的TDP-43聚集体。

PROJECT ABSTRACT/SUMMARY Many degenerative neuromuscular diseases are associated with cytoplasmic accumulation of protein aggregates. These aggregates are widely considered to contribute disease and thus are thought to be toxic to the cell. Recently, we discovered similar aggregates, termed myo-granules, in healthy regenerating and differentiating skeletal muscle. Myo-granules contain RNA and RNA-binding proteins. One prominent RNA- binding protein found in myo-granules, TDP-43, is of particular interest due to its presence in aggregates observed in degenerative disease. Further, myo-granules localize to developing sarcomeres and contain an abundance of sarcomeric mRNAs that bear TDP-43 binding-sites. As the muscle regenerates and sarcomeres are replaced, myo-granules are cleared and TDP-43 re-localizes to the nuclei. Together, these findings suggest that TDP-43 may play a role in facilitating sarcomere formation and that accumulation of TDP-43 containing- aggregates found in disease may not be the cause but instead the result of recurring attempts at skeletal regeneration. In pre-liminary work, I found that TDP-43 deletion in muscle stem cells prevents differentiation, identifying an essential role for TDP-43 in skeletal muscle. Specific Aim 1 will evaluate the role of TDP-43 in myofiber formation and maturation during regeneration. To accomplish this, I will delete TDP-43 at regenerative checkpoints for fusion of differentiated cells and for maturation of the regenerating muscle. The results from aim 1 will be used to inform experiments in Specific Aim 2 where I will analyze the role of TDP- 43 in sarcomere formation. In pre-liminary work, TDP-43 deletion in differentiating cells during regeneration results in muscle that is improperly repaired and myofiber size is drastically reduced. Additionally, myofiber maturation is reduced when TDP-43 is deleted as indicated by the continued expression of developmental sarcomeric proteins. Thus, is TDP-43 required for sarcomere regeneration and repair? I will ask this question by taking an in vivo approach where TDP-43 will be deleted in both healthy and regenerating muscle to evaluate the effect on sarcomere formation, maturation, and degradation. Delineating the function of TDP-43 in sarcomere formation should lead to a better understanding of the relationship between myo-granules and disease-associated TDP-43 aggregates.