Comparative genetics of cardiac chamber formation

描述(由申请人提供)：识别控制心腔形成的遗传途径很可能阐明导致许多心脏结构性出生缺陷的分子机制。心脏同源结构域转录因子基因Nkx2-5在心脏发育中起关键作用： Nkx2-5是小鼠正常心腔形成所必需的，人类Nkx2-5的突变是先天性心脏病家族性病例的基础。尽管Nkx2-5在心脏调节体系中具有明显的重要性，但Nkx2-5通路的下游成分及其在心腔形成中的作用尚不清楚。PI假设心腔形成的基本效应基因是Nkx2-5途径的进化保守成分。为了验证这一假设，他们提出了一个为期两年的探索性项目，该项目结合了耶隆和哈维实验室的专业知识，对斑马鱼和老鼠的Nkx2-5功能进行了比较遗传分析。具体地说，他们将首先描述斑马鱼心脏的分子解剖学特征，作为比较分析的基础。应用这些知识，他们将比较斑马鱼和老鼠中Nkx2-5基因家族的功能丧失表型。然后，利用老鼠和斑马鱼基因组学的进展，他们将结合微阵列分析和比较基因表达研究，确定这两个物种Nkx2-5下游的基因。最后，随着注意力集中在保守的途径组件上，他们将利用斑马鱼反向遗传学来测试它们在心腔形成过程中的作用。总之，拟议的实验将揭示Nkx2-5途径的保守角色和组件。此外，通过利用两种模式生物的互补优势，PI将开发一种新的方法来对心脏基因表达谱进行功能注释。

DESCRIPTION (provided by applicant): The identification of genetic pathways controlling cardiac chamber formation is likely to illuminate the molecular mechanisms responsible for many cardiac structural birth defects. The cardiac homeodomain transcription factor gene Nkx2-5 is known to play a key role in cardiac development: Nkx2-5 is essential for normal chamber formation in mice, and mutations in human Nkx2-5 underlie familial cases of congenital heart disease. Despite the clear importance of Nkx2-5 in the cardiac regulatory hierarchy, the downstream components of the Nkx2-5 pathway and their contributions to cardiac chamber formation are not well understood. The PIs hypothesize that the essential effector genes for cardiac chamber formation are evolutionarily conserved components of the Nkx2-5 pathway. To test this hypothesis, they propose a two-year exploratory project that combines the expertise of the Yelon and Harvey laboratories for a comparative genetic analysis of Nkx2-5 function in zebrafish and mouse. Specifically, they will begin by characterizing the molecular anatomy of the zebrafish heart as a foundation for comparative analysis. Applying this knowledge, they will compare the loss-of-function phenotypes for the Nkx2-5 gene family in zebrafish and mouse. Then, taking advantage of advances in both mouse and zebrafish genomics, they will combine microarray analysis and comparative gene expression studies to identify genes downstream of Nkx2-5 in both species. Finally, with attention focused on conserved pathway components, they will utilize zebrafish reverse genetics to test their roles during cardiac chamber formation. Together, the proposed experiments will reveal conserved roles and components of the Nkx2-5 pathway. Furthermore, by capitalizing on the complementary advantages of two model organisms, the PIs will develop a new approach for functional annotation of cardiac gene expression profiles.