Interplay between lipophagy and mitophagy in skeletal muscle aging

 描述（由申请人提供）：肌肉质量、功能和损伤后的组织修复随着骨骼肌的老化而减少。自噬似乎起着关键作用，但其影响仍然存在争议。混杂因素是肌肉中存在的多种类型的细胞（例如肌纤维，卫星细胞，巨噬细胞），它们可能具有不同的自噬要求，以及自噬机制如何靶向特定的细胞器类型（例如线粒体或脂滴）。目前尚不清楚衰老骨骼肌中共存细胞类型的自噬如何变化，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。精确定位在复杂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途径的技术并不容易获得。为了解决当前的一些技术限制，本申请提出了开发和使用质谱细胞术来进行单细胞蛋白质组学和个体细胞器毛细管电泳来研究衰老骨骼肌中自噬的细胞器群体。本研究的主要目的是：（1）建立单细胞水平的细胞计数方法，以监测肌纤维、巨噬细胞和卫星细胞中自噬相关的分子变化。(2)建立个体细胞器毛细管电泳策略，选择性地描述肌纤维，巨噬细胞和卫星细胞中的脂肪吞噬和线粒体自噬。(3)使用根据目标1和3开发的方法，定义在基础和组织损伤/修复条件下衰老的鼠模型中的脂肪吞噬、线粒体吞噬和整体自噬的变化。这项工作的完成将提供新的技术进步来微调自噬的特征，并将为自噬在骨骼肌系统衰老中的争议性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.