UNDERSTANDING THE ROLE OF MITOCHONDRIAL QUALITY CONTROL

线粒体质量控制（mitochondrialqualitycontrol，mQC）是近年来线粒体生物学领域的一个新的研究方向，它是一种调控线粒体组分降解的机制。事实上，最近已经发现了几种mQC机制，最著名的是线粒体自噬，但它们在各种细胞类型中的作用，它们的相互关系水平以及它们在体内的生理相关性仍然知之甚少。该计划旨在使用具有不同设计和功能的横纹肌和免疫细胞来回答这些问题。我们将重点关注两种mQC机制：i）线粒体自噬（通过自噬选择性清除整个线粒体），和ii）细胞来源的囊泡（MDV：通过囊泡分泌过程选择性清除线粒体组分）的产生。 第一部分：肌细胞中的线粒体QC：维持线粒体的适应性和最佳功能池对于正常收缩活动至关重要。出于这个原因，我们假设在肌细胞中，mQC与线粒体含量/活性相称，并且这些机制以分层方式起作用。更具体地说，我们假设MDV生产是基线线粒体管家的主要机制，以及对线粒体应激的早期反应，而当整个细胞器过度损伤时，线粒体自噬变得更加主导。为了测试这一点，将使用c2 c12成肌细胞/肌管来表征基线时和响应于已知强制mQC响应的条件的线粒体功能、线粒体自噬、MDV产生和细胞表型。遗传方法将被用来专门调节线粒体自噬和MDV生产，以阐明其作用。这也将在WT和转基因小鼠中使用各种方法（包括定量形态学电子显微镜）进行体内研究。 第二部分：巨噬细胞（M）中的线粒体QC：在M中，线粒体在促（M1）和抗（M2）炎症反应的发展中发挥作用，但潜在的机制仍不清楚。 我们推测，线粒体自噬和MDV生产的调制，在这一过程中起着重要的作用，通过改变线粒体功能，线粒体抗原呈递免疫信号。为了测试该原始M和原代骨髓源性M将在体外暴露于促炎或抗炎刺激物。线粒体功能将与线粒体自噬、MDV产生、线粒体抗原呈递和M分化标志物一起分析。遗传方法和转基因小鼠将用于调节线粒体自噬和MDV的生产，以阐明它们在M分化/激活中的作用。还将进行体内研究以检查mQC对免疫反应的作用。 总的来说，这项工作将提供重要的信息，在线粒体和细胞功能的mQC的作用。

Mitochondrial quality control (mQC), which refers to the mechanisms governing the regulated degradation of mitochondrial components, is an emerging facet in the field of mitochondrial biology. Indeed, several mQC mechanisms, the best known being mitophagy, have been uncovered recently, but their role in various cell types, their level of inter-relation, and their physiological relevance in vivo, remain poorly understood. This program aims to answer these questions using striated muscle and immune cells which have different designs and functions. We will focus on two mQC mechanisms: i) mitophagy (the selective clearance of whole mitochondria through autophagy), and ii) production of mitochondrial-derived vesicles (MDVs: the selective clearance of mitochondrial components through a vesicle secretion process). Part 1: Mitochondrial QC in muscle cells: Maintenance of an adapted and optimally functioning pool of mitochondria is critical for normal contractile activity. For this reason we hypothesize that in myocytes mQC is commensurate to mitochondrial content/activity, and that these mechanisms act in a hierarchical manner. More specifically, we postulate that MDV production is a predominant mechanism for baseline mitochondrial housekeeping, and early response to mitochondrial stress, while mitophagy becomes more predominant when excessive damage to whole organelles is present. To test this, c2c12 myoblasts/myotubes will be used to characterize mitochondrial functions, mitophagy, MDV production, and cellular phenotype at baseline and in response to conditions known to force a mQC response. Genetic approaches will be used to specifically modulate mitophagy and MDV production in order to elucidate their role. This will also be studied in vivo in WT and transgenic mice using various approaches including quantitative morphological electron microscopy. Part 2: Mitochondrial QC in macrophages (M): In M, mitochondria play a role the development of pro (M1) and anti (M2)-inflammatory responses, but the underlying mechanisms remain unclear. We hypothesize that modulation of mitophagy and MDV production, plays an important role in this process by altering mitochondrial functions, and mitochondrial antigen presentation for immune signalling. To test this Raw M and primary bone marrow-derived M will be exposed to pro- or anti-inflammatory stimuli in vitro. Mitochondrial functions will be analyzed together with mitophagy, MDV production, mitochondrial antigen presentation, and M differentiation markers. Genetic approaches and transgenic mice will be used to modulate mitophagy and MDV production in order to elucidate their role in M differentiation/activation. In vivo studies will also be conducted to examine the role of mQC on the immune response. Overall this work will provide important information on the role of mQC in mitochondrial and cellular functions.