Effect of exercise on skeletal muscle-derived extracellular vesicles and regulation of mitochondrial biogenesis

骨骼肌（SkM）具有高度适应性，在决定全身代谢能力方面起着关键作用。慢性运动（CE）的金标准反应是线粒体含量和活性的增加，称为线粒体生物发生（MB）。虽然SkM内调节MB的机制已被广泛研究，但对SkM如何驱动系统适应知之甚少。最受关注的是SkM释放的蛋白质，称为肌因子，可以直接释放，也可以包装在称为细胞外囊泡（ev）的载体中，将它们运送到循环系统中。电动汽车是一种进化保守的细胞间通讯方式，可以从所有细胞中释放出来，并且含有可以改变受体细胞功能的生化货物。先前的研究表明，CE促进了全身EV浓度的增加，改变了EV的载货量，并且这些EV引起了保护性适应。然而，这些ev大多来自血清/血浆，其中含有来自身体所有组织的ev。CE对skm - ev的特异性影响，以及它们在介导对CE（如MB）的系统适应中的作用尚不清楚。这是一个关键的知识缺口，因为SkM是最大的器官系统之一，在CE期间执行体力工作，是肌因子的储存库，并且已知可以调节代谢性能。我假设CE修饰skm - ev，而这些skm - ev可以介导MB的增加。我实验室新颖而令人兴奋的试点数据支持这一假设。我的国家科学研究委员会DG研究计划将使用尖端的分子生物学技术来解决这一差距。我们将使用体外慢性收缩活动（CCA）模型，使用已建立和验证的技术分离和测量skm - ev。skm - ev将与其他细胞共培养，并测量MB的变化。我们将对SkM细胞进行基因修饰，使其表达一种特定的酶（cre），对其进行CCA，分离ev并注射到双报告小鼠中。在这个模型中，吸收skm - ev的组织将从红色荧光切换到绿色荧光。由于只有skm - ev含有cre酶，该模型将使我们能够定量跟踪cca后体内skm - ev。将收集代谢活性组织，确认EV摄取，并评估cca - skm -EV慢性治疗后MB的变化。因此，我的HQP将确定CCA对skm - ev的影响，并发现skm - ev是否可以使用创新的机械技术调节MB。短期结果将导致具有里程碑意义的发现，这将创造关于CCA对SkM-EV的影响及其对MB的影响的新知识。我的NSERC DG研究计划的长期目标是阐明SkM-EV生物发生、释放和摄取的上游机制，以及介导MB的下游信号通路。我的计划将推动生物技术和应用生理学领域的跨学科研究，以推进知识。有利于和加速加拿大的研究，促进HQP培训。

Skeletal muscle (SkM) is highly adaptable and plays a critical role in determining whole-body metabolic capacity. The gold standard response to chronic exercise (CE) is an increase in mitochondrial content & activity termed mitochondrial biogenesis (MB). While mechanisms regulating MB within SkM have been studied extensively, less is known about how SkM drives systemic adaptations. The lion's share of attention has been attributed to proteins released from SkM termed myokines, that can be released directly, or packaged in carrier vehicles called extracellular vesicles (EVs) to ferry them in the circulatory system. EVs are an evolutionary conserved method of intercellular communication, are released from all cells and contain biochemical cargo that can modify function in recipient cells. Previous work has shown that CE promotes an increase in systemic EV concentration, changes EV cargo, and that these EVs evoke protective adaptations. However, these EVs were mostly obtained from serum/plasma which contain EVs from all tissues in the body. The effect of CE specifically on SkM-EVs, and their role in mediating systemic adaptations to CE e.g. MB remains unknown. This is a critical gap in knowledge, as SkM is one of the largest organ systems, performs the physical work during CE, a reservoir of myokines, and known to regulate metabolic performance. I hypothesize that CE modifies SkM-EVs and that these SkM-EVs can mediate an increase in MB. Novel and exciting pilot data from my lab support this hypothesis. My NSERC DG research program will use cutting-edge molecular biology techniques to address this gap. We will use an in vitro model of chronic contractile activity (CCA) to isolate and measure SkM-EVs using established & validated techniques. SkM-EVs will be co-cultured with other cells, and changes in MB measured. We will genetically modify SkM cells to express a specific enzyme (cre), subject them to CCA, isolate EVs and inject into a double-reporter mouse. In this model, tissues that take up SkM-EVs will switch from red to green fluorescence. Since only the SkM-EVs contain the cre enzyme, this model will allow us to quantitatively track SkM-EVs in vivo post-CCA. Metabolically-active tissues will be harvested, EV uptake confirmed and changes in MB evaluated post-chronic treatment with CCA-SkM-EVs. Thus, my HQP will determine the effect of CCA on SkM-EVs & discover whether SkM-EVs can regulate MB using innovative and mechanistic techniques. The short-term results will lead to landmark discoveries that will create new knowledge about the effects of CCA on SkM-EVs and their effect on MB. The long-term goals of my NSERC DG research program are to elucidate upstream mechanisms of SkM-EV biogenesis, release and uptake, and downstream signalling pathways that mediate MB. My program will fuel interdisciplinary research with biotechnology and applied physiology fields to advance knowledge, benefit and accelerate Canadian research and promote HQP training.