Regulation of cardiac chamber morphogenesis in zebrafish

描述（由申请人提供）：胚胎脊椎动物心脏由两个主要腔室组成，一个心室和一个心房，每个腔室都具有定义其功能能力的特征形态。先天性心脏病常与畸形的心腔有关，但心腔形态发生的调控机制尚不清楚。心腔形态发生可分为2个主要阶段：心管组装，其中双侧前体群体联合形成管，以及腔室出现，其中这个简单的圆柱体转变为一系列形态上离散的腔室。我们研究的长期目标是确定调节这2个室形态发生阶段的细胞和分子机制。以斑马鱼为模式生物，我们可以联合收割机结合胚胎学和遗传学方法，使用高分辨率实时成像来确定关键基因如何影响心肌细胞行为。我们对心管组装的初步时间推移分析表明，这一过程是由多个基因驱动的，这些基因合作调节定向心肌细胞运动的区域差异。此外，我们最初的形态分析室出现表明，这一过程是受支配的。通过内在和外在因素控制心肌细胞形态的局部变化。最后，我们最近对新突变的研究表明，心脏基因的缓慢融合和变化分别是心管组装和心腔出现的关键调节因子。在此基础上，我们建议测试（1）心肌细胞运动如何受到临界细胞量的调节，极化上皮的形成，与内胚层和内皮细胞的相互作用以及缓慢融合功能，以及（2）心肌细胞形态如何受到血流动力学，肌节完整性，与内皮细胞的相互作用以及心脏功能变化的调节。总之，这些研究将揭示心脏发生的基本调控机制，也丰富了我们对器官形成一般范式的理解。

DESCRIPTION (provided by applicant): The embryonic vertebrate heart is composed of 2 major chambers, a ventricle and an atrium, each with a characteristic morphology that defines its functional capacity. Congenital heart defects are often associated with dysmorphic cardiac chambers, but the regulation of cardiac chamber morphogenesis is not well understood. Cardiac chamber morphogenesis can be divided into 2 major phases: heart tube assembly, in which bilateral precursor populations unite to form a tube, and chamber emergence, in which this simple cylinder transforms into a series of morphologically discrete chambers. The long-term goal of our research is to identify the cellular and molecular mechanisms that regulate these 2 phases of chamber morphogenesis. Using the zebrafish as a model organism, we can combine embryologic and genetic approaches, using high-resolution live imaging to determine how key genes influence cardiomyocyte behavior. Our preliminary time-lapse analyses of heart tube assembly suggest that this process is driven by multiple genes that collaborate to regulate regional differences in directed cardiomyocyte movements. Additionally, our initial morphometric analyses of chamber emergence suggest that this process is governed. by both intrinsic and extrinsic factors that control regional changes in cardiomyocyte morphology. Finally, our recent studies of novel mutations suggest that the slow fuse and change of heart genes are critical regulators of heart tube assembly and chamber emergence, respectively. Building on this foundation, we propose to test (1) how cardiomyocyte movements are regulated by a critical mass of cells, formation of polarized epithelia, interactions with endoderm and endocardium, and slow fuse function, and (2) how cardiomyocyte morphology is regulated by hemodynamics, sarcomere integrity, interactions with the endocardium, and change of heart function. Together, these studies will reveal essential regulatory mechanisms of cardiogenesis and also enrich our understanding of general paradigms for organ formation.