UNDERSTANDING THE ROLE OF MITOCHONDRIAL QUALITY CONTROL

线粒体质量控制（mQC）是线粒体生物学领域的一个新兴领域，是指控制线粒体成分降解的机制。事实上，最近已经发现了几种mQC机制，其中最著名的是有丝分裂，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。该项目旨在利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。我们将重点关注两个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)线粒体源性囊泡的产生（mdv：通过囊泡分泌过程选择性清除线粒体成分）。***第1部分：肌肉细胞中的线粒体质量控制：维持线粒体的适应和最佳功能池对正常收缩活动至关重要。因此，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的产生是基线线粒体内控和线粒体应激的早期反应的主要机制，而当整个细胞器存在过度损伤时，线粒体自噬变得更加主要。为了验证这一点，c2c12成肌细胞/肌管将被用来表征线粒体功能、线粒体自噬、MDV产生和细胞表型，在基线和已知条件下强制mQC反应。遗传学方法将用于特异性调节线粒体自噬和MDV的产生，以阐明它们的作用。这也将在WT和转基因小鼠体内使用各种方法进行研究，包括定量形态电子显微镜。***第2部分：巨噬细胞中的线粒体QC （MΦ）：在MΦ中，线粒体在促（M1）和抗（M2）炎症反应的发展中起作用，但其潜在机制尚不清楚。我们假设线粒体自噬和MDV产生的调节通过改变线粒体功能和免疫信号的线粒体抗原呈递在这一过程中起着重要作用。为了测试这一点，Raw MΦ和原代骨髓来源的MΦ将在体外暴露于促炎或抗炎刺激下。线粒体功能将与线粒体自噬、MDV产生、线粒体抗原呈递和MΦ分化标志物一起进行分析。遗传学方法和转基因小鼠将用于调节线粒体自噬和MDV的产生，以阐明它们在MΦ分化/激活中的作用。还将进行体内研究，以检验mQC在免疫反应中的作用。***总的来说，这项工作将提供关于mQC在线粒体和细胞功能中的作用的重要信息。**************

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 (MΦ): In MΦ, 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 MΦ and primary bone marrow-derived MΦ 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 MΦ differentiation markers. Genetic approaches and transgenic mice will be used to modulate mitophagy and MDV production in order to elucidate their role in MΦ 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.**************