Role of skeletal muscle mitophagy in healthy aging

骨骼肌线粒体自噬在健康衰老中的作用

基本信息

批准号：
9761948
负责人：
Josh C Drake
金额：
$ 10.33万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-15 至 2019-12-24
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9761948
关键词：
Age Aging Animals Autophagocytosis Biosensor Confocal Microscopy Development Disease Elderly Electric Stimulation Excision Exercise Fostering Foundations Functional disorder Gastrocnemius Muscle Geroscience Holoenzymes Human Immunohistochemistry Impairment In Vitro Intervention Knock-out Knockout Mice Learning Longevity Maintenance Mediating Mentors Metabolic Microscopy Mitochondria Mitochondrial Proteins Mus Muscle Muscle Fibers Muscle Mitochondria Phase Phosphorylation Phosphotransferases Photosensitization Plantaris muscle Preparation Proteins Proteomics Quality Control RNA interference screen Regulation Reporting Research Resolution Reticulum Role Sarcolemma Signal Transduction Skeletal Muscle Somatic Gene Therapy Stains Stress Testing Tissues Training Wild Type Mouse Work age related career development confocal imaging effective intervention flexor digitorum brevis healthy aging imaging approach improved in vivo insight irradiation mimetics muscle aging novel programs recruit response skills tibialis anterior muscle two photon microscopy two-photon

项目摘要

Project Summary Mitochondrial quality in skeletal muscle progressively declines with advancing age, leading to tissue dysfunction and disease. Several lines of evidence suggest poor mitochondrial quality in skeletal muscle of old animals and humans is due in large part to an impaired or insufficient capacity to degrade damaged/dysfunctional mitochondria via mitophagy. Exercise promotes mitochondrial quality leading to healthy aging but the underlying mechanisms and how they differ with age is not well defined, particularly in regards to mitophagy, restraining development of effective interventions. Building upon my previous work demonstrating that exercise does indeed promote mitophagy in skeletal muscle but only of a small fraction of the total mitochondrial reticulum, I show here evidence of an Ampk-dependent mechanism that may distinguish damaged vs. healthy regions of the mitochondrial reticulum that is lost with age. Additionally, I show that key downstream mitophagy-related factors that are recruited to mitochondria in skeletal muscle with exercise are required for mitochondrial quality and healthy aging in d. melanogaster. The proposed research tests the hypothesis that recognition of damaged regions of the mitochondrial reticulum in response to exercise is impaired in skeletal muscle of old mice, blunting local recruitment of key mitophagy proteins, leading to poor mitochondrial quality. These studies will provide insight into novel regulation of skeletal muscle mitophagy in response to exercise and lay a foundation for the development of targeted interventions to promote mitochondrial quality in skeletal muscle for improved tissue function and healthy aging. During the mentored phase, I will employ state-of-the-art two-photon microscopy to perform intravital and ex vivo fluorescent lifetime microscopy of Ampk activity on mitochondria in skeletal muscle of young and old mice to determine the age-dependent, localized response of Ampk to sustained contraction and mitochondrial damage. Also, I will continue my professional and scientific development in preparation for the independent phase with continuous guidance from my mentoring committee. During the independent phase, I will employ co-somatic gene transfer in skeletal muscle of young and old wild-type mice as well as skeletal muscle-specific, conditional Ulk1 knock-out mice to determine the age-dependent regulation for the recruitment of downstream mitophagy-related factors to mitochondria in skeletal muscle in response to exercise. Also, I will develop novel phospho-mimetic constructs to constitutively activate or inhibit mitophagy-related factors Atg9 and Atg2 in young and old mouse skeletal muscle and investigate their necessity and sufficiency for the breakdown of mitochondrial proteins and maintenance of mitochondrial quality, via state-of-the-art high resolution proteomic and confocal imaging approaches. Collectively, these studies and career development activities will foster my continued scientific and professional training, leading to a successful independent, academic research program.

项目概要骨骼肌的线粒体质量随着年龄的增长逐渐下降，导致组织功能障碍和疾病。多项证据表明，老年动物骨骼肌中的线粒体质量较差，人类在很大程度上是由于降解受损/功能失调的能力受损或不足线粒体通过线粒体自噬。运动可以促进线粒体质量，从而实现健康衰老，但潜在的机制以及它们如何随年龄变化尚不明确，特别是在线粒体自噬、抑制制定有效的干预措施。以我之前的工作为基础，证明锻炼确实可以促进骨骼肌中的线粒体自噬，但仅促进总线粒体网的一小部分，我在这里展示 Ampk 依赖性机制的证据，可以区分受损的区域与健康的区域随着年龄的增长而丢失的线粒体网。此外，我还表明下游线粒体自噬相关的关键因素通过运动被招募到骨骼肌线粒体中的线粒体是线粒体质量所必需的， d. 健康老龄化黑腹果蝇。所提出的研究测试了识别损坏的假设年老小鼠骨骼肌中线粒体网状区域对运动的反应受到损害，从而变得迟钝关键线粒体自噬蛋白的局部募集，导致线粒体质量较差。这些研究将提供深入了解骨骼肌线粒体自噬响应运动的新调节，并为制定有针对性的干预措施以促进骨骼肌中的线粒体质量以改善组织功能和健康老龄化。在指导阶段，我将采用最先进的双光子显微镜来对骨骼肌线粒体上的 Ampk 活性进行活体和离体荧光寿命显微镜检查对年轻和年老小鼠进行实验，以确定 Ampk 对持续收缩的年龄依赖性局部反应和线粒体损伤。此外，我将继续我的专业和科学发展，为独立阶段得到我的指导委员会的持续指导。在独立阶段，我将在年轻和年老野生型小鼠的骨骼肌以及骨骼中采用共体基因转移肌肉特异性、条件性 Ulk1 敲除小鼠，以确定招募的年龄依赖性调节下游线粒体自噬相关因子对运动反应中骨骼肌线粒体的影响。另外，我也会开发新型磷酸模拟结构来组成性激活或抑制线粒体自噬相关因子 Atg9 和 Atg2在年轻和年老小鼠骨骼肌中的表达及其分解的必要性和充分性通过最先进的高分辨率蛋白质组学分析线粒体蛋白质并维持线粒体质量和共焦成像方法。总的来说，这些学习和职业发展活动将培养我持续的科学和专业培训，导致成功的独立学术研究项目。