Genetic and Molecular Analysis of Mouse Mutants with Congenital Heart Defects

描述(申请人提供)：房间隔是分离四足动物体肺循环的关键步骤，房间隔缺陷是人类先天性心脏病(CHD)最常见的形式之一。本项目的目的是研究房间隔分离和房间隔祖细胞规范所需的细胞和分子机制。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例，基于第二心场的贡献(Mommersteig等人，2006年；Snarr等人，2007b；Goddeeris等人，2008年)。我们已经确定了房间隔特异的心脏祖细胞亚群。第二心后区的Hedgehog信号标志着房间隔祖细胞。这些发现表明，房间隔和非间隔细胞的命运是在祖细胞规格的水平上区分的，而不是通过随后在发育中的心房内获得的位置信息来区分的。这些新鉴定的前体细胞被指定并产生房间隔的分子机制目前尚不清楚。在这里，我们提出了一种综合的方法，使用正向和反向遗传学来构建房间隔分离所需的分子通路，并研究房间隔祖细胞的特性。我们的具体目标是(1)分析房间隔祖细胞在野生型和Hedgehog信号突变胚胎中的特性、增殖和存活；(2)分析CaC2突变小鼠的房间隔祖细胞和HH信号；以及(3)确定房间隔形成所需的新基因CaC2的分子基础。在授权期结束时，将对房间隔祖细胞规格和功能的分子基础有更深入的了解。这项工作将有助于我们对心脏间隔缺陷个体发育的理解发生正在进行的范式转变。与公共卫生相关：房间隔是分离四足动物体循环和肺循环的关键步骤，房间隔缺陷是人类先天性心脏病最常见的形式之一。本项目的目的是为了更好地了解房间隔祖细胞的特性和功能。这项工作的长期目标是了解房间隔缺陷的个体发生。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: 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. The objective of this project is to gain a better understanding of atrial septal progenitor cell specification and function. The long- term goal of this work is to understand the ontogeny of atrial septal defects.