Mechanisms of cardiomyocyte-extracellular matrix interactions in cardiogenesis

摘要 适当的心脏发育对于一生中有效的心脏功能是必不可少的。先天性心脏病 先天缺陷(CHD)是最常见的先天性畸形，发生在高达1%的活产儿和10%的 死产。CHDS还会增加成年人患心血管疾病的风险。在脊椎动物的心脏 在发育过程中，心肌祖细胞被丰富的细胞外基质(ECM)包围。基因突变 人类体内的几种ECM蛋白可以导致CHD。然而，CHD背后的机制与 对于影响ECM的突变，人们仍然知之甚少。来自ECM的信号由整合素检测 靶细胞上的受体。我们对斑马鱼在两种情况下都携带功能丧失突变的初步分析 整合素α5和整合素α4基因表明，这些整合素反复需要促进 适当的心脏形态发生和脑室大小。这项提议的总体目标是阐明机制 心肌细胞解释和整合来自ECM的信号以执行正确的心肌细胞 迁徙和心脏发育。这项建议的具体目标是：目标1--确定 整合素信号介导心肌细胞的正常迁移。这一目标将使用组织学技术和 活胚胎的共聚焦时间推移显微镜检验整合素信号促进定向的假说 通过建立有组织的极化上皮进行心肌细胞迁移；目标2-确定 整合素在脑室发育中的作用这一目标结合了心肌细胞数量的量化和时间 分化试验检验整合素通过促进晚些时候的细胞因子增加来驱动心脏生长的假说。 将第二心区(SHF)心肌细胞区分为心室和流出道；目的3-确定 整合素在促进心肌细胞迁移和SHF中的组织特异性和时间要求 加法。目的是利用新的转基因品系在空间和时间上调节整合素的表达，以检测 整合素信号在心肌细胞中特异作用的假说，首先促进心肌细胞 迁徙，后来促进第二心场的增加。通过阐明不同的心肌细胞是如何 群体整合并解释来自周围ECM的信号，我们的结果可能提供对 人类先天性心脏病的病因学，并可应用于旨在修复 高效的心脏功能。

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.