Mitochondrial Quality Control is Essential for Cardiac Progenitor Cell Function

描述（由申请人提供）：心脏祖细胞（CPCs）在再生中的激活和参与对于病理性损伤后的有效修复至关重要。我们发现CPC激活和谱系承诺涉及增加的能量需求和线粒体生物发生的激活。虽然线粒体的主要功能是通过氧化磷酸化为细胞提供ATP，但线粒体可以迅速成为促进死亡的细胞器。不足为奇的是，细胞已经形成了一种防御机制，以抵御可能伤害细胞的异常线粒体。E3泛素连接酶Parkin通过自噬体-溶酶体途径标记功能失调的线粒体。不幸的是，衰老与自噬减少有关，这导致功能失调的线粒体去除不足。CPC中线粒体自噬的调控以及线粒体功能与CPC衰老之间的关系基本上是未知的。在这一提议中，我们将探索CPCs线粒体质量控制随着年龄的增长而减少的假设，这导致缺陷线粒体的积累和功能受损。这一假设将通过两个目标来验证。在Aim 1中，我们将确定线粒体DNA （mtDNA）突变和衰老对CPC功能的影响。使用携带校对缺陷mtDNA聚合酶γ (POLGm/m)的小鼠模型，我们将研究累积mtDNA突变对线粒体功能以及cpc的存活、增殖和分化的影响。我们还将比较WT和POLGm/m CPCs在体外和体内的活力和功能，并评估损伤后心脏功能修复和改善的程度和效率。在Aim 2中，我们将研究帕金森介导的有丝分裂在不同年龄的WT和POLGm/m cpc中的功能作用。我们还将在体外和体内探讨帕金森缺乏症对cpc的功能影响。这些研究将提供新的见解，通过自噬线粒体清除在cpc中的重要性。我们也将获得对CPC基本功能和生存的重要新认识，最终可用于增强其在损伤心脏中的再生能力。

DESCRIPTION (provided by applicant): Activation and participation of cardiac progenitor cells (CPCs) in regeneration are critical for effective repair in the wake of pathologic injury. We have found that CPC activation and lineage commitment involve increased energy demand and activation of mitochondrial biogenesis. Although the primary function of mitochondria is to provide the cell with ATP through oxidative phosphorylation, mitochondria can quickly become death- promoting organelles. Not surprisingly, cells have developed a defense mechanism against aberrant mitochondria that can harm the cell. The E3 ubiquitin ligase Parkin marks dysfunctional mitochondria for degradation by the autophagosome-lysosomal pathway. Unfortunately, aging is associated with reduced autophagy, which leads to inadequate removal of dysfunctional mitochondria. The regulation of mitochondrial autophagy in CPCs and the correlation between mitochondrial function and CPC aging are essentially unknown. In this proposal, we will explore the hypothesis that mitochondrial quality control in CPCs is reduced with age, which leads to accumulation of defective mitochondria and impaired function. This hypothesis will be tested with two aims. In Aim 1, we will determine the effect of mitochondrial DNA (mtDNA) mutations and aging on CPC function. Using a mouse model carrying a proofreading defective mtDNA polymerase gamma (POLGm/m), we will investigate the effect of accumulating mtDNA mutations on mitochondrial function, as well as survival, proliferation, and differentiation of CPCs. We will also compare viability and function of WT and POLGm/m CPCs in vitro and in vivo, and evaluate the extent and efficiency of repair and improvement in cardiac function after injury. In Aim 2, we will investigate the functional role of Parkin-mediated mitophagy in WT and POLGm/m CPCs at different ages. We will also explore the functional consequences of Parkin-deficiency in CPCs in vitro and in vivo. These studies will provide novel insights into the importance of mitochondrial clearance via autophagy in CPCs. We will also gain important new understanding of basic CPC function and survival, which can ultimately be used to enhance their regenerative capacity in the injured heart.