Genetic and Molecular Analysis of Mutants with Congenital Heart Defects

项目摘要 房间隔是分离全身和肺的关键步骤。 四足循环和房间隔缺损是最常见的形式之一。 人类先天性心脏病(CHD)。这项计划的目的是调查 房间隔和房间隔形成所需的细胞和分子机制 祖细胞规格。 房间隔的标准观点是基于心脏内的形态发生事件。 然而，我们实验室和其他实验室最近的工作已经产生了一种新的范式 房间隔，基于第二心场的贡献(Mommersteig等人， 2006年；Snarr等人，2007年b；Goddeeris等人，2008年)。我们已经确定了 房间隔特异的心脏祖细胞。刺猬发出的信号 第二心后野标记房间隔祖细胞。这些发现意味着 在祖细胞水平上区分房间隔和非间隔细胞的命运 规范，而不是通过在 发展中庭。这些新表征的分子机制 祖细胞被指定并产生房间隔，目前尚不清楚。 在这里，我们提出了一种使用正向和反向遗传学的综合方法 建立房间隔分离所需的分子通路，并研究 房间隔祖细胞规范。我们的具体目标是(1)分析 房间隔祖细胞的分化、增殖和存活 Hedgehog信号突变胚胎；(2)分析房间隔祖细胞和HH CaC2突变小鼠的信号转导；以及(3)鉴定新基因CaC2的分子基础 房间隔隔离所需的。对心房的分子基础有更深入的了解 间隔祖细胞的规格和功能将在 授权期。这项工作将有助于我们正在进行的范式转变 对心脏间隔缺损个体发生的认识。

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.