Early Cardiac Progenitors

项目总结/摘要 哺乳动物的心脏在胚胎发育早期就形成了，其形成过程中的缺陷是先天性心脏病的根源。 心脏缺陷（CHD），影响1-2%的活产婴儿。在成年人中，心脏病是头号杀手。 西方世界，造成相当大的健康负担。出生后的终末分化状态 心脏意味着受损的心肌在损伤时永久丧失（例如，心肌梗塞后）。 了解心脏的组成部分不仅对确定冠心病的病因具有明确的重要性， 还可以创造新的基于细胞的再生策略来治疗心脏病。心脏的起源 胚胎发生被定义为在原肠胚形成期间产生的中胚层中开始。我们有 确定Smarcd 3作为标记Mesp 1谱系标记细胞的早期亚群，其贡献几乎 专门针对心脏。我们已经在这个祖先库中确定了亚群，它们有助于 与正在形成的心脏的特定解剖结构有关。具体而言，Tbx 5谱系标记的细胞有助于 心房和左心室，而Mef 2AHF谱系标记的细胞主要贡献于流出道和右心室。 脑室使用新的双谱系标记方法，我们确定，除了这两个广泛的 在早期胚胎中，有第三个细胞亚群被这两种标记物标记， 选择性地向室间隔的一侧精细地延伸，形成尖锐的谱系边界。这 令人惊讶的发现表明，心源性中胚层的形成非常早， 在形态发生之前，祖先已经注定了未来的解剖位置。我们已经确定 减少TBX 5剂量，导致心室间隔缺损，破坏了谱系的完整性， 边界这是第一次允许分子遗传解剖的机制，调节一个特定的 对于隔膜形成必不可少的细胞群。这些发现重新定义了心脏的起源 室，并提供了令人兴奋的新途径，了解心脏细胞的命运和形态发生。在这 使用转基因报告细胞系结合单细胞RNA-seq的建议，我们将以无偏见的方式 定义了小鼠晚期原肠胚中早期心脏祖细胞的范围。我们还将定义 通过克隆谱系追踪的特定遗传标记群体的贡献。我们将定义起源， 身份和迁移的一个特定的细胞群，专门有助于室间隔。 我们将研究通过减少其剂量来破坏这种谱系形成的边界的影响。 调节因子TBX 5，并在室间隔形态发生之前或期间删除该细胞群。 最后，我们将确定消除特定转录调节因子功能的影响， 中胚层和心脏分化对早期心脏谱系的建立和迁移的影响。

Project Summary/Abstract The mammalian heart forms early in embryogenesis, and defects in its formation are at the root of congenital heart defects (CHDs), affecting 1–2% of live births. In adulthood, heart disease is the number one killer in the Western world, resulting in a considerable health burden. The terminally differentiation state of the postnatal heart means that damaged myocardium is permanently lost upon injury (e.g., after a myocardial infarction). Understanding the building blocks of the heart has clear importance not only for defining the etiology of CHDs, but also for creating novel cell-based regeneration strategies to treat heart disease. The origins of the heart in embryogenesis have been defined as beginning in mesoderm that arises during gastrulation. We have identified Smarcd3 as marking an early subpopulation of Mesp1 lineage-labeled cells, which contribute almost exclusively to the heart. We have already identified subpopulations within this progenitor pool, which contribute to specific anatomical structures of the forming heart. Specifically, Tbx5 lineage-labeled cells contribute to the atria and left ventricle, while the Mef2AHF lineage labeled cells contribute largely to the outflow tract and right ventricle. Using a novel dual-lineage labeling method, we determined that in addition to these two broad populations, there is a third subset of cells labeled by both markers in the early embryo that contribute exquisitely and selectively to one side of the interventricular septum, forming a sharp lineage boundary. This surprising finding suggests a very early and refined patterning of cardiogenic mesoderm, with some progenitors already destined to a future anatomical location, ahead of morphogenesis. We have determined that reduced TBX5 dosage, which results in ventricular septation defects, disrupts the integrity of the lineage boundary. This for the first time allows a molecular genetic dissection of the mechanisms regulating a specific population of cells that are essential for septal formation. These findings redefine the origins of the cardiac chambers, and provide exciting new avenues to understand cardiac cell fate and morphogenesis. In this proposal using transgenic reporter lines combined with single cell RNA-seq we will in an unbiased manner define the range of early cardiac progenitors that populate the late mouse gastrula. We will also define the contribution of specific genetically labeled populations by clonal lineage tracing. We will define the origins, identity, and migration of a specific cell population that contributes exclusively to the interventricular septum. We will examine the effect of disrupting the boundary that this lineage forms, by reduced dosage of its regulator, TBX5, and by deleting this cell population prior to or during ventricular septal morphogenesis. Finally, We will determine the effects of eliminating the function of specific transcriptional regulators of mesoderm and cardiac differentiation on the establishment and migration of early cardiac lineages.