Cardiomyocyte heterogeneity and aging

 描述(由申请人提供)：该项目旨在确定成年小鼠心室中心肌细胞群体的复杂性，并特别强调了解支持成人心脏损伤后再生的增殖心肌细胞的性质。我们从成年小鼠心脏的增殖心肌细胞是单核和二倍体的角度出发，这对应于小鼠新生心脏和斑马鱼成年心脏的增殖群体，以及所有物种胚胎心脏的增殖群体。我们建议克服与这种概念化有关的几个悬而未决的问题，这些问题阻碍了该领域的进展。首先，成人单核二倍体心肌细胞群体的异质性程度尚不清楚，特别是与具有增殖能力的亚群相关。其次，目前还没有分子标记可以区分增殖性和非增殖性心肌细胞。第三，这些人群随着时间的推移在心脏中的动态是完全未知的，但对于了解老年人心力衰竭的患病率可能是至关重要的。在目标1中，我们将对分离自成年小鼠的单核二倍体、单核四倍体和双核心肌细胞进行单细胞RNA序列分析，并将显示差异表达的基因或基因亚型定义了这些心肌细胞组和亚群。这种方法将证明心肌细胞异质性的程度，同时将验证这些群体的标记物，这些标记物可以用于随后的一些研究。作为一个特别重要的应用，我们将确定哪些标记物标记损伤后增殖的心肌细胞。在目标2中，我们将解决这些种群随时间的动态变化，特别是将年轻成年小鼠与老年成年小鼠进行比较。我们将在几个模型中进行解析，以解释心肌细胞再生随年龄增长而下降的观察结果。总而言之，该项目将创新的概念化与新技术相结合，以解决以前无法获得的关于心肌细胞群体的亚结构和动力学的问题。

 DESCRIPTION (provided by applicant): This project seeks to define the complexity of cardiomyocyte populations in the adult mouse ventricle, and has a specific emphasis on understanding the nature of proliferative cardiomyocytes that support adult heart regeneration after injury. We begin from the perspective that proliferative cardiomyocytes in the adult mouse heart are mononuclear and diploid, which corresponds to the proliferative population in mouse neonatal and zebrafish adult hearts and to the proliferative population in the embryonic hearts of all species. We propose to overcome several outstanding issues related to this general conceptualization that have impeded progress in the field. First, the extent to which the adult mononuclear diploid cardiomyocyte population is heterogeneous is unknown, particularly as related to subpopulations that have proliferative competence. Second, no molecular markers currently exist that identify proliferative cardiomyocytes from nonproliferative. Third, the dynamics of these populations in the heart over time are completely unknown, but are likely of critical importance in understanding the prevalence of heart failure in the elderly. In Aim 1, we will undertake single cell RNA Seq analysis of mononuclear diploid, mononuclear tetraploid, and binuclear cardiomyocytes isolated from adult mice, and will show that genes or gene isoforms that are differentially expressed define groups and subpopulations of these groups of cardiomyocytes. This approach will demonstrate the extent of cardiomyocyte heterogeneity and at the same time will validate markers of these populations that can be used in a number of subsequent studies. As one particularly important application, we will identify which markers label proliferative cardiomyocytes after injury. In Aim 2, we will address the dynamics of these populations over time, in particular comparing young adult to aged adult mice. We will resolve among several models to explain the observation that cardiomyocyte regeneration declines with advanced age. In all, this project combines an innovative conceptualization with new technology to address questions about the substructure and dynamics of cardiomyocyte populations that have not previously been accessible.