Regulation of myogenesis and skeletal muscle function by bioactive lipid class switching

原理：新肌肉组织的形成，称为肌发生，是一个受到严格调控的过程，在骨骼肌的发育和生长中起着至关重要的作用。在这个过程中，肌肉干细胞（musc）进入细胞周期，成为增殖的成肌细胞，最终自我更新或分化并融合形成新的肌肉纤维。***在肌发生过程中，MuSCs的细胞命运决定是如何被调控的，这是该领域非常感兴趣的问题。我们的研究项目提出，生物活性脂类转换是调节MuSCs细胞命运决定的核心过程。脂质介质类转换是脂肪酸（如ω -3或-6）最初转化为促炎脂质的过程；然后是促分解脂质。这个过程在炎症的调节中起着关键作用；然而，它对musc的影响从未被研究过。更好地理解肌发生过程中MuSC决策的调控机制将为体外调控其细胞命运决策提供新的可能性，这是该领域的一个重大挑战。******目的与假设：本研究项目的总体目标是表征脂质介质类别转换对MuSC和骨骼肌功能的影响。我们假设在肌形成过程中存在一个开关，有利于促分解脂质的生物合成，从而促进晚期肌形成事件（如细胞分化和融合）。该提案分为三个目标：******目标1：定义肌发生过程中生物活性脂质介质类别的转换。利用生物分子技术（质谱、RT-qPCR、western blot），我们将评估肌肉形成不同阶段MuSCs生物活性脂质及其受体的表达。***目的2：确定脂质介质类转换对肌源性细胞周期调节的作用机制和影响。利用缺乏生物活性脂质生物合成酶的MuSC，我们将确定脂质介质类别切换对MuSC细胞命运决定的影响及其作用机制。***目的3：确定生物活性脂类切换对肌管和骨骼肌功能的影响。通过体外和体内实验，我们将评估生物活性脂类切换对新形成的肌肉纤维和骨骼肌功能的影响。******相关性：我们期望这个研究项目将揭示一个在肌肉发生过程中调控MuSC决策的全新机制，这在该领域具有广泛和当前的兴趣。这个研究项目将为我们的研究计划奠定基础，旨在开发新的方法来调节干细胞的命运。特别是，体外细胞干细胞的维持是生物工程师、研究人员和生命科学行业的广泛兴趣，这将导致与加拿大学术界和工业界建立牢固的伙伴关系。

Rationale: The formation of new muscle tissue, named myogenesis, is a tightly regulated process that plays a vital role in skeletal muscle development and growth. During that process, muscle stem cells (MuSCs) enter the cell cycle to become proliferating myoblasts, which eventually self-renew or differentiate and fuse to form new muscle fibers. ***How the cell fate decision of MuSCs is regulated during myogenesis is of great interest in the field. Our research project proposes that bioactive lipids class switching is a central process regulating the cell fate decision of MuSCs. Lipid mediator class switching is a process during which fatty acids (such as omega-3 or -6) are initially transformed into pro-inflammatory lipids; and thereafter into pro-resolving lipids. This process plays a key role in the regulation of inflammation; however, its impact on MuSCs has never been investigated. A better comprehension of the mechanisms regulating MuSC decision-making during myogenesis will open new possibilities to regulate their cell fate decision in vitro, which is a great challenge in the field.******Objective and hypothesis: The overall goal of this research project is to characterize the impact of lipid mediator class switching on MuSC and skeletal muscle function. We hypothesize that there is a switch during myogenesis that favours the biosynthesis of pro-resolving lipids, which promote late myogenic events (such as cell differentiation and fusion). This proposal is divided in 3 aims:******Aim 1: Define the bioactive lipid mediator class switching during myogenesis. Using biomolecular techniques (mass spec, RT-qPCR, western blot), we will assess the expression of bioactive lipids and their receptors by MuSCs at different stages of myogenesis.***Aim 2: Determine the mechanism of action and the impact of lipid mediator class switching on cell cycle regulation of myogenic cells. Using MuSC deficient in the enzymes responsible for bioactive lipid biosynthesis, we will determine the impact and the mechanism of action of lipid mediator class switching on the cell fate decision of MuSCs.***Aim 3: Determine the effect of bioactive lipids class switching on myotube and skeletal muscle function. Using in vitro and in vivo experiments we will assess the impact of bioactive lipid class switching on the function of newly-formed muscle fiber and skeletal muscles.******Relevance: We expect that this research project will uncover a completely novel mechanism regulating MuSC decision-making during myogenesis, which is of broad and current interest in the field. This research project will set the foundation stone of our research program aiming to develop novel methods to regulate stem cell fate. Particularly, the maintenance of cell stemness in vitro is of wide interest for bioengineers, investigators, and life science industries, which will lead to the development of strong partnerships with academia and industries in Canada.