Secretion of mitochondria as a cellular quality control mechanism

线粒体的分泌作为细胞质量控制机制

基本信息

批准号：
10521290
负责人：
Asa B. Gustafsson
金额：
$ 56.57万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-12-20 至 2024-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10521290
关键词：
Autophagocytosis Autophagosome Cardiac Cardiovascular Diseases Cardiovascular system Cell membrane Cell secretion Cells Cessation of life Compensation Complex Contracts Data Defect Defense Mechanisms Degradation Pathway Development Disease Docking Early Endosome Endosomes Endothelial Cells Ensure Fibroblasts Functional disorder Goals Heart Homeostasis Impairment In Vitro Inflammation Label Lysosomes Macrophage Mediating Mitochondria Molecular Mus Muscle Cells Myocardial Infarction Myocardium Myofibroblast Organelles Oxidative Phosphorylation Parkin Pathway interactions Plasma Play Process Proteomics Quality Control Research Role Route Stress System Testing Ubiquitination Vesicle Western Blotting angiogenesis diagnostic biomarker exosome extracellular vesicles in vivo insight knock-down late endosome new therapeutic target novel postmitotic prevent programs rab GTP-Binding Proteins trafficking ubiquitin-protein ligase uptake

项目摘要

Project summary In the heart, the primary function of mitochondria is to meet the high energy demand of the beating myocytes by providing ATP through oxidative phosphorylation. However, mitochondria can quickly change into death-promoting organelles. Not surprisingly, cells have developed multiple defense mechanisms against aberrant mitochondria that can cause harm to the cell. The ability to eliminate dysfunctional mitochondria and prevent unnecessary death is particularly important in post-mitotic myocytes that cannot be easily replaced. It is well established that dysfunctional mitochondria are rapidly sequestered by autophagosomes and subsequently delivered to lysosomes for degradation. Recent studies have identified cells that can also eliminate mitochondria via a Rab9-dependent alternative autophagy pathway or via a Rab5-dependent-early endosomal pathway. Mitochondria can also be directly taken up by lysosomes. Clearly, multiple pathways of mitochondrial elimination exist in cells to prevent their accumulation and ensure survival. However, these degradation pathways all converge at the level of the lysosomes and it is not clear whether alternative mitochondrial quality control pathways exists when lysosomal function is compromised. We have discovered that dysfunctional mitochondria can also be secreted from cells when internal degradation pathways are overwhelmed or impaired. Our preliminary data demonstrate that Rab7-/- and LAMP2-/- cells that have impaired lysosomal degradation are still able to efficiently eliminate depolarized mitochondria. We also found increased levels of circulating extracellular vesicles (EVs) containing mitochondria in plasma after a myocardial infarction, as well as in cardiac specific Rab7- and LAMP2-deficient mice at baseline. Proteomics analysis of EVs combined with Western blot analysis suggest that the mitochondria are in vesicles that originate from the endosomal pathway. In this proposal, we will investigate the hypothesis that dysfunctional mitochondria are secreted from cells in EVs and that this represent an important quality control pathway in the heart that can compensate when lysosomes are overwhelmed or compromised. This hypothesis will be tested with two specific aims. Specific aim 1 will identify the origin and fate of the extracellular vesicles containing mitochondria and determine the pathophysiological conditions that induce their release from myocytes. Specific aim 2 will dissect the molecular mechanisms regulating secretion of mitochondria in EVs. Overall, these studies will provide important new insights into a novel alternative mechanism of mitochondrial elimination in the myocardium. The studies will also provide insights into whether these EVs can potentially function as early diagnostic biomarkers of cardiac stress prior to development of disease.

项目摘要在心中，线粒体的主要功能是满足跳动的高能量需求通过通过氧化磷酸化提供ATP来提供心肌细胞。但是，线粒体可以迅速变成促进死亡的细胞器。毫不奇怪，细胞已经开发了多种防御机制可能对细胞造成伤害的异常线粒体。消除功能失调的线粒体和预防不必要的死亡在无法容易替换的有丝分裂后肌细胞中特别重要。这是很好地确定，功能障碍的线粒体被自噬体迅速隔离，随后递送到溶酶体降解。最近的研究已经确定了也可以消除线粒体的细胞通过依赖于RAB9的替代自噬途径或通过RAB5依赖性的内体途径。线粒体也可以直接被溶酶体吸收。显然，线粒体消除的多种途径存在于细胞中以防止其积累并确保生存。但是，这些降解途径ack 在溶酶体的水平上收敛，目前尚不清楚是否替代线粒体质量控制当溶酶体功能受到损害时，途径存在。我们发现线粒体功能失调当内部降解途径不堪重负或受损时，也可以从细胞中分泌。我们的初步数据表明rab7 - / - 和Lamp2 - / - 细胞损害溶酶体降解仍然能够有效消除去极化的线粒体。我们还发现循环细胞外的水平增加心肌梗塞后血浆中包含线粒体的囊泡（EV）以及心脏特异性基线时的RAB7和LAMP2缺陷小鼠。电动汽车的蛋白质组学分析与蛋白质印迹分析结合表明线粒体位于源自内体途径的囊泡中。在这个建议中，我们将研究以下假设：功能失调的线粒体从电动汽车中的细胞分泌，这是代表心脏中重要的质量控制途径，可以在溶酶体为时进行补偿不知所措或折衷。该假设将以两个具体的目的进行检验。具体目标1将确定包含线粒体的细胞外囊泡的起源和命运，并确定病理生理学导致其从肌细胞释放的条件。特定的目标2将剖析分子机制调节电动汽车中线粒体的分泌。总体而言，这些研究将为一个重要的新见解心肌中线粒体消除的新型替代机制。研究还将提供了解这些电动汽车是否可以作为心脏应力的早期诊断生物标志物的发挥作用疾病的发展。