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

基本原理：新的肌肉组织的形成，称为肌生成，是一个严格调控的过程，在骨骼肌的发育和生长中起着至关重要的作用。在此过程中，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纤维。* MuSC的细胞命运决定在肌发生期间如何被调节在该领域中是非常感兴趣的。我们的研究项目提出，生物活性脂质类转换是调节MuSCs细胞命运决定的中心过程。脂质介体类别转换是脂肪酸（例如ω-3或ω-6）最初转化为促炎脂质;然后转化为促消退脂质的过程。这一过程在炎症调节中起着关键作用;然而，其对MuSC的影响从未被研究过。更好地理解肌肉发生过程中调节MuSC决策的机制将为体外调节其细胞命运决定开辟新的可能性，这是该领域的一个巨大挑战。目的和假设：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，有一个开关在肌生成过程中，有利于生物合成的亲解决脂质，促进后期肌事件（如细胞分化和融合）。该提议分为3个目的：** 目的1：定义肌生成期间的生物活性脂质介质类别转换。使用生物分子技术（质谱、RT-qPCR、蛋白质印迹），我们将评估MuSC在肌生成的不同阶段的生物活性脂质及其受体的表达。目的2：确定脂质介质类别转换对肌源性细胞细胞周期调控的作用机制和影响。使用缺乏负责生物活性脂质生物合成的酶的MuSC，我们将确定脂质介质类别转换对MuSC的细胞命运决定的影响和作用机制。目的3：确定生物活性脂质类转换对肌管和骨骼肌功能的影响。使用体外和体内实验，我们将评估生物活性脂质类别转换对新形成的肌纤维和骨骼肌功能的影响。相关性：我们希望这项研究项目将揭示一种全新的机制，调节肌肉发生过程中的MuSC决策，这在该领域具有广泛的和当前的兴趣。该研究项目将为我们的研究计划奠定基础，旨在开发调节干细胞命运的新方法。特别是，细胞干细胞在体外的维护是生物工程师，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的强有力的伙伴关系的发展。

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.