Genetic and Molecular Analysis of Mutants with Congenital Heart Defects

项目摘要 心房分隔是分离体循环和肺循环的关键步骤 四足动物和房间隔缺损中的循环是最常见的形式， 人类先天性心脏病（CHD）。本项目的目的是调查 房间隔形成和房间隔缺损的细胞和分子机制 祖细胞特化 房间隔的经典观点是基于心内形态发生事件。 然而，我们实验室和其他实验室最近的工作产生了一种新的范式， 心房分隔，基于第二心脏区域的贡献（Mommersteeg等人， 2006; Snarr等人，2007 b; Goddeeris等人，2008年）。我们发现了一个 心房隔膜特异性的心脏祖细胞。中的刺猬信号传导 后第二心野标记房间隔祖细胞。这些发现意味着 房间隔细胞与非房间隔细胞的命运在祖细胞水平上是不同的 而不是由随后在规范内获取的位置信息来确定。 发展中庭。这些新特征的分子机制 祖细胞是指定的，并产生房间隔目前是未知的。 在这里，我们提出了一个综合的方法，同时使用正向和反向遗传学 建立心房间隔形成所需的分子通路， 房间隔祖细胞的特化。我们的具体目标是（1）分析 野生型和非野生型中房间隔祖细胞的特化、增殖和存活 Hedgehog信号突变胚胎;（2）分析房间隔祖细胞和Hh cac2突变小鼠的信号传导;（3）鉴定cac2（一种新基因）的分子基础 房间隔形成所需要的。更深入地了解心房颤动的分子基础 间隔祖细胞的规格和功能将在结束时交付 授予期。这项工作将有助于在我们的国家正在进行的范式转变。 了解心脏间隔缺损的个体发生。

Project Summary Atrial septation is a critical step in separating the systemic and pulmonary circulations in tetrapods and atrial septal defects are among the most common forms of human congenital heart disease (CHD). The objective of this project is to investigate the cellular and molecular mechanisms required for atrial septation and atrial septal progenitor cell specification. The canonical view of atrial septation is based on intracardiac morphogenetic events. However, recent work in our laboratory and others has engendered a novel paradigm for atrial septation, based on contributions from the second heart field (Mommersteeg et al., 2006; Snarr et al., 2007b; Goddeeris et al., 2008). We have identified a subset of cardiac progenitor cells specific for the atrial septum. Hedgehog signaling in the posterior second heart field marks atrial septal progenitors. These findings imply that atrial septum vs. non-septum cell fate is distinguished at the level of progenitor cell specification rather than by positional information acquired subsequently within the developing atrium. The molecular mechanisms by which these newly characterized progenitor cells are specified and generate the atrial septum are currently unknown. Here, we propose an integrative approach using both forward and reverse genetics to build a molecular pathway required for atrial septation and investigate the specification of atrial septal progenitors. Our specific aims are to (1) Analyze the specification, proliferation, and survival of atrial septal progenitors in wild-type and Hedgehog signaling mutant embryos; (2) Analyze atrial septal progenitors and Hh signaling in cac2 mutant mice; and (3) Identify the molecular basis of cac2, a novel gene required for atrial septation. A greater understanding of the molecular basis of atrial septal progenitor cell specification and function will be delivered at the end of the granting period. This work will contribute to an ongoing paradigm shift in our understanding of the ontogeny of cardiac septal defects.