Fbxw7 as a target to promote muscle stem cell expansion

摘要 这项提案的目标是定义促进肌肉干细胞(MUSC)扩增的新方法。MUSC 是骨骼肌生长和再生的主要来源。这种细胞群体能够自我更新， 即产生大量的祖细胞来修复受损的组织，同时产生更多的 通过细胞分裂来维持干细胞库。MUSC在健康成人组织中以静止状态存在 在压力或损伤时，它们被激活以增殖和修复受损的组织。虽然这一过程 在健康的条件下，在几种疾病状态下，以及在衰老过程中，MUSC的功能受到损害 这极大地损害了组织的维护和功能。然而，它们的临床效用是 治疗工具和靶点目前由于我们对分子网络的有限了解而受到阻碍。 调节它们的功能。因此，迫切需要填补这一空白，并确定能够促进 MUSC扩增和组织修复，因为这些将被应用于体外疾病建模以及 在慢性条件下促进骨髓间充质干细胞介导的组织再生。我们的初步结果提供了证据 调节多个成体干细胞隔室的E3泛素连接酶Fbxw7促进MUSC 承诺和分化，以及它的基因消融导致了体内强大的MUSC扩增。的关注点 拟议的研究是在MUSC命运转变过程中动态定位Fbxw7蛋白靶点，并 评估其瞬时抑制作为促进MUSC扩增的新方法。我们的研究将需要 (1)可诱导的Pax7-Creer；Fbxw7f/f新型动物模型的优点；(2)优化的整体蛋白质组学 MUSC图谱的方法，(3)使用Fbxw7抑制剂进行瞬时操作，以及(4)人类MUSC 从病人身上分离出来，以验证跨物种的保护。总之，这项探索性研究将提供一种 初步了解Fbxw7如何影响MUSC细胞命运决策，并确定可以利用的新工具 对于再生医学方法，以增强骨髓间充质干细胞的扩张和疾病条件下的组织修复。

SUMMARY The goal of this proposal is to define novel approaches to promote muscle stem cells (MuSC) expansion. MuSC are the major source of skeletal muscle growth and regeneration. This cell population is capable of self-renewal, i.e. generating large number of progenitors to repair damaged tissue and at the same time more copies of themselves upon cell division to maintain the stem cell pool. MuSC exist in healthy adult tissues in a quiescent state, and upon stress or injury they are activated to proliferate and repair the damaged tissue. While this process is efficient in healthy conditions, in several diseased states and during aging the function of MuSC is impaired and this significantly contribute to impaired tissue maintenance and function. However, their clinical utility as therapeutic tools and targets is currently hindered by our limited understanding of the molecular networks regulating their function. Thus, there is a major need to fill this gap and define novel approaches that can promote MuSC expansion and tissue repair, as these would find applications for disease modeling in vitro as well as for promoting MuSC-mediated tissue regeneration in chronic conditions. Our preliminary results provide evidence that the E3 ubiquitin ligase Fbxw7, which regulates multiple adult stem cell compartments, promotes MuSC commitment and differentiation, and its genetic ablation leads to robust MuSC expansion in vivo. The focus of the proposed studies is to dynamically map Fbxw7 protein targets during MuSC fate transitions, and to evaluate its transient inhibition as a novel approach to promote MuSC expansion. Our research will take advantage of (1) the inducible Pax7-CreER;Fbxw7f/f novel animal model, (2) an optimized global proteomics approach for MuSC profiling, (3) the use of Fbxw7 inhibitors for its transient manipulation, and (4) Human MuSC isolated from patients, to validate conservation across species. Together, this exploratory study will provide an initial understanding of how Fbxw7 impacts MuSC cell fate decisions and identify novel tools that can be utilized for regenerative medicine approaches to enhance MuSC expansion and tissue repair in diseased conditions.