Mechanisms of cardiomyocyte-extracellular matrix interactions in cardiogenesis

总结 适当的心脏发育对于整个生命中有效的心脏功能至关重要。先天性心脏 先天性心脏病（CHD）是最常见的先天性畸形，发生率高达1%的活产婴儿和10%的 仍然出生。冠心病还可能导致成年人患心血管疾病的风险增加。在脊椎动物心脏 在发育过程中，心肌祖细胞被丰富的细胞外基质（ECM）包围。突变 人体中的几种ECM蛋白可导致CHD。然而，冠心病相关的机制 对影响ECM的突变仍知之甚少。来自ECM的信号由Integrin检测 靶细胞上的受体。我们对斑马鱼进行了初步的分析，这些斑马鱼在两个基因上都有功能缺失突变， 整合素α 5和整合素α 4基因表明这些整合素反复需要促进 正确的心脏形态发生和心室大小。本提案的总体目标是阐明 心肌细胞通过其解释和整合来自ECM的信号以执行适当的心肌细胞 迁移和心脏生长。本提案的具体目标是：目标1-确定机制， 整合素信号传导介导适当的心肌细胞迁移。这一目标将使用组织学技术， 活胚胎的共聚焦时间推移显微镜，以测试整合素信号传导促进定向的假设， 通过建立有组织的极化上皮细胞来促进心肌细胞迁移;目的2-确定 心室发育中的整合素。这一目标结合心肌细胞数量定量和时间 分化测定来测试整合素通过促进添加后- 将第二心脏区域（SHF）心肌细胞区分为心室和流出道;目的3-确定 整合素促进心肌细胞迁移和SHF的组织特异性和时间要求 的增订条文该目的使用新的转基因株系在空间和时间上调节整合素表达，以测试 整合素信号传导在心肌细胞中特异性起作用，首先促进心肌细胞 迁移，后来促进第二心脏领域的补充。通过阐明心肌细胞 群体整合和解释来自周围ECM的信号，我们的研究结果可能提供洞察力， 病因学，并可应用于新的组织工程疗法，旨在恢复 有效的心脏功能。

SUMMARY Proper heart development is essential for efficient heart function throughout life. Congenital heart defects (CHDs) are the most common congenital malformations, occurring in up to 1% of live births and 10% of still births. CHDs can also lead to increased risk of cardiovascular diseases in adults. During vertebrate heart development, cardiomyocyte progenitors are surrounded by a rich extracellular matrix (ECM). Mutations in several ECM proteins in humans can lead to CHDs. However, the mechanisms underlying CHDs associated with mutations that affect the ECM remain poorly understood. Signals from the ECM are detected by Integrin receptors on target cells. Our preliminary analysis of zebrafish carrying loss-of-function mutations in both the Integrin alpha5 and Integrin alpha4 genes indicate that these Integrins are reiteratively required to promote proper cardiac morphogenesis and ventricle size. The overall goal of this proposal is to elucidate mechanisms by which cardiomyocytes interpret and integrate signals from the ECM to execute proper cardiomyocyte migration and heart growth. The Specific Aims of this proposal are: Aim 1 - Determine mechanisms by which Integrin signaling mediates proper cardiomyocyte migration. This aim will use histological techniques and confocal time lapse microscopy of live embryos to test the hypothesis that Integrin signaling promotes directed cardiomyocyte migration by establishing an organized, polarized epithelium; Aim 2 - Determine the role of Integrins in ventricle development. This aim combines cardiomyocyte number quantification and temporal differentiation assays to test the hypothesis that Integrins drive heart growth by promoting addition of later- differentiating second heart field (SHF) cardiomyocytes to the ventricle and outflow tract; Aim 3 - Determine the tissue-specific and temporal requirements for Integrins in promoting cardiomyocyte migration and SHF addition. This aim uses novel transgenic lines to spatially and temporally regulate Integrin expression to test the hypothesis that Integrin signaling acts specifically in the cardiomyocytes, first to promote cardiomyocyte migration, and later to promote second heart field addition. By illuminating how different cardiomyocyte populations integrate and interpret signals from the surrounding ECM, our results may provide insight into the etiology of CHDs in humans, and can be applied to novel tissue engineering therapies aimed at restoring efficient heart function.