Interplay between lipophagy and mitophagy in skeletal muscle aging

 描述(申请人提供)：骨骼肌的肌肉质量、功能和损伤后的组织修复随着年龄的增长而减少。自噬似乎发挥了关键作用，但其可能的影响仍存在争议。混杂因素是肌肉中存在的多种类型的细胞(例如肌肉纤维、卫星细胞、巨噬细胞)，它们可能有不同的自噬要求，以及自噬机制如何针对特定类型的细胞器(例如线粒体或脂滴)。目前尚不清楚自噬如何改变衰老骨骼肌中共存的细胞类型，细胞器特异性自噬有多普遍，以及细胞器特异性自噬类型之间是否存在协调。在复杂的组织和共存形式的自噬中观察到的变化背后的分子和细胞通路的精确定位的技术还不容易获得。为了解决目前的一些技术局限性，本应用提出了发展和使用质量细胞术来进行单细胞蛋白质组学和单个细胞器毛细管电泳法来研究衰老骨骼肌中自噬的细胞器群。这项建议的目的是：(1)建立质量细胞术策略，在单细胞水平上监测肌肉纤维、巨噬细胞和卫星细胞中与自噬相关的分子变化。(2)建立单个细胞器毛细管电泳法，选择性地描述肌纤维、巨噬细胞和卫星细胞的吞脂性和有丝分裂性。(3)使用根据AIMS 1和3开发的方法学，在基础和组织损伤/修复条件下的衰老小鼠模型中定义脂噬、有丝分裂吞噬和整体自噬的变化。拟议工作的完成将为微调自噬的特征提供新的技术进步，并将为自噬在骨骼肌系统老化中的有争议的作用提供更具体的答案。

 DESCRIPTION (provided by applicant): Muscle mass, function, and tissue repair after injury decrease with aging in skeletal muscle. Autophagy appears to play a critical role, but what the effects might be are still controversial. Confounding factors are the multiple types of cells present in the muscle (e.g. muscle fibers, satellite cells, macrophages), which may have different autophagy requirements, and how the autophagy machinery targets specific organelle types (e.g. mitochondria or lipid droplets). It is not known how autophagy changes in coexisting cell types in the aging skeletal muscle, how prevalent are organelle-specific autophagy, and whether there is coordination between organelle-specific autophagy types. Techniques to pinpoint to the molecular and cellular pathways behind the changes observed in complex tissues and co-existing forms of autophagy are not readily available. In order to address some of the current technological limitations, this application proposes the development and use of mass cytometry to carry out single cell proteomics and individual organelle capillary electrophoresis to investigate organelle populations of autophagy in aging skeletal muscle. The aims of this proposal are: (1) Establish mass cytometry strategies to monitor at the single cell level autophagy-related molecular changes in muscle fibers, macrophages, and satellite cells. (2) Establish individual-organelle capillary electrophoretic strategies that selectively describe lipophagy and mitophagy in muscle fibers, macrophages, and satellite cells. (3) Define changes in lipophagy, mitophagy and global autophagy in a murine model of aging under basal and tissue injury/repair conditions using the methodologies developed under Aims 1 and 3. Completion of the proposed work will provide new technological advances to fine tune the characterization of autophagy and will provide more concrete answers to the controversial role of autophagy in the aging of the skeletal muscle system.