Skeletal Muscle Nrf2: Exercise-Induced Cardiovascular Protection

项目摘要 本研究的目的是阐明运动训练（ExT）诱导的交感神经系统损伤的新机制。 抑制慢性心力衰竭（CHF）（目的1）和急性冠状动脉粥样硬化性心脏病后心脏保护 缺血/再灌注（I/R）（目标2），基于抗氧化剂器官间转移的创新概念 内切酶众所周知，运动产生肌肉来源的活性氧（ROS）， 激活核因子（红细胞衍生2）样2（Nrf 2），导致一组抗氧化剂的上调 骨骼肌中的酶我们假设这些抗氧化剂可以从骨骼 通过循环细胞外囊泡（EV）将肌肉转移到远端组织，为受体细胞提供 抗氧化防御的第二道防线。在小鼠延髓头端腹外侧区（RVLM）， CHF，这些抗氧化剂恢复前交感神经元的氧化还原稳态，有助于ExT-交感神经元的氧化还原稳态。 抑制作用此外，在接受冠状动脉I/R的小鼠心脏中，这些抗氧化剂减少了自由基 损伤和挽救缺血心肌，从而在ExT心脏保护中发挥关键作用。解决 基于这些假设，我们开发了三种骨骼肌特异性转基因小鼠品系。MS-mG线是一种 报告模型，它允许我们跟踪，捕获和分析从骨骼肌特异性释放的EV。 该模型将用于检测骨骼肌源性EV的货物蛋白及其在脑中的分布 和心脏跟随ExT。iMS-Nrf 2flox/flox和iMS-Keap 1flox/flox行将使我们能够删除骨骼肌 Nrf 2（即Nrf 2缺陷）和Keap 1（即Nrf 2过表达）。这两种模式将用于 证明目标1中Nrf 2/抗氧化系统和ExT-交感神经抑制之间的因果关系 和Aim 2中的ExT-心脏保护。EV生物学、蛋白质组学、生物信息学的跨学科方法， 电生理学和心血管生理学将用于表征骨骼肌衍生的EV ExT后，测定ExT-EV对中枢神经元放电和外周交感神经的影响 活性，并探讨ExT-EV对冠状动脉I/R损伤的心脏保护作用的机制。 在这个项目完成后，我们希望提供新的机制的见解外，心血管 保护，铺平了一条新的途径，将定期身体活动的有益效果转化为临床 实践，以预防和治疗急性和慢性缺血性心脏病。

PROJECT SUMMARY The goal of this study is to elucidate novel mechanisms underlying exercise training (ExT)-induced sympatho- inhibition in chronic heart failure (CHF) (Aim 1) and cardioprotection following acute coronary ischemia/reperfusion (I/R) (Aim 2), based on an innovative concept of inter-organ transfer of antioxidant enzymes. It is well established that exercise generates muscle-derived reactive oxygen species (ROS) which activates nuclear factor (erythroid-derived 2)-like 2 (Nrf2), resulting in upregulation of a panel of antioxidant enzymes in skeletal muscle per se. We hypothesize that these antioxidants can be transported from skeletal muscle to remote tissues through circulating extracellular vesicles (EVs), providing recipient cells with a second and enhanced line of antioxidant defense. In the rostral ventrolateral medulla (RVLM) of mice with CHF, these antioxidants restore redox homeostasis of pre-sympathetic neurons, contributing to ExT-sympatho- inhibition. Furthermore, in the heart of mice subjected to coronary I/R, these antioxidants reduce free radical damage and salvage ischemic myocardium, thus playing a critical role in ExT-cardioprotection. To address these hypotheses, we developed three skeletal muscle-specific transgenic mouse lines. The MS-mG line is a reporter model, which allows us to track, capture, and analyze EVs released specifically from skeletal muscle. This model will be used to assay cargo proteins of skeletal muscle-derived EVs and their distribution in brain and heart following ExT. The iMS-Nrf2flox/flox and iMS-Keap1flox/flox lines will enable us to delete skeletal muscle Nrf2 (i.e. Nrf2 deficiency) and Keap1 (i.e. Nrf2 overexpression), respectively. These two models will be used to demonstrate a causal relationship between the Nrf2/antioxidant system and ExT-sympatho-inhibition in Aim 1 and ExT-cardioprotection in Aim 2. Interdisciplinary methods of EV biology, proteomics, bioinformatics, electrophysiology, and cardiovascular physiology will be utilized to characterize skeletal muscle-derived EVs following ExT, determine the effects of ExT-EVs on central neuron discharge and peripheral sympathetic nerve activity, and explore the mechanisms underpinning cardioprotection of ExT-EVs against coronary I/R injury. Upon completion of this project, we expect to provide novel mechanistic insights on ExT-cardiovascular protection, paving a new avenue to translate the beneficial effects of regular physical activity into clinical practice to prevent and treat acute and chronic ischemic heart diseases.