Genetic Analyst of Early Conduction System Development

描述（由申请人提供）：了解专门的心室心脏传导系统的发展对心律失常的生物治疗和掌握心脏组织再生至关重要。心律失常和猝死是一些伴有异常小梁或非压实的心肌病的特征。小梁状心室心肌的发育和维持是心脏器官发生的一个关键过程，似乎与通过erbb2/神经调节蛋白（nrg）信号传导的成熟心室心脏传导模式的正常发育有关。我们已经知道erbb2/nrg通路在传导系统发育中起作用。然而，无论是小梁的过程，还是它在发展传导系统中所起的作用，都还不清楚。本研究的长期目标是描述专门传导系统的早期结构和功能，并确定小梁与传导系统发展的关系。这个项目的具体目标是双重的。首先，我们将建立斑马鱼特化心室心脏传导系统的分子标记。我们将验证以下假设，即传导系统的第一个细胞位于小梁心肌层，以及通过分析这些标记物的表达来评估小梁突变体缺乏传导系统细胞。其次，我们将验证一个假设，即传导系统的发展需要小梁的过程，而不仅仅是nrg/erbb2途径。斑马鱼是一个有用的模型生物，因为它的遗传易感性，半透明的胚胎发生，和相似的人类电生理表型和疾病。为了鉴定传导细胞，我们将使用原位杂交和抗体染色的候选标记在整个安装和切片斑马鱼的心脏。为了评估野生型、突变型和基因改变心脏的传导系统发育，我们将使用光学作图和胚胎心电图监测。我们将评估erbb2突变体的传导表型，以及在注入心脏特异性显性阴性结构的野生型胚胎中，这种结构旨在阻断参与小梁形成的其他途径。研究发育中的心脏传导系统的结构和功能及其与小梁的关系将进一步加深我们对先天性和获得性心肌病心律失常的理解，并将为通过操纵传导细胞治疗室性心律失常和猝死提供工具和知识。

DESCRIPTION (provided by applicant): Understanding development of the specialized ventricular cardiac conduction system is critical to generating biologic treatments for arrhythmia and mastering cardiac tissue regeneration. Arrhythmia and sudden death characterize several cardiomyopathies with aberrant trabeculation or noncompaction. The development and maintenance of trabeculated ventricular myocardium is a key process in heart organogenesis and appears linked to the normal development of a mature ventricular cardiac conduction pattern by way of erbb2/neuregulin (nrg) signaling. The erbb2/nrg pathway is already known to play a part in conduction system development. However, neither the process of trabeculation nor its role in setting the stage for the developing conduction system is understood. The long-term goals of this research are to describe the early structure and function of the specialized conduction system, and to determine how trabeculation relates to conduction system development. The specific aims of this project are twofold. First, we will establish molecular markers of the specialized ventricular cardiac conduction system in zebrafish. We will test the hypotheses that the location of the first cells of the conduction system are located in the trabeculating myocardial layer, and that trabeculation mutants lack conduction system cells as assessed by analyzing the expression of these markers. Second, we will test the hypothesis that the process of trabeculation, and not just the nrg/erbb2 pathway, is required for conduction system development. The zebrafish is a useful model organism for these experiments due to its genetic tractability, translucent embryogenesis, and similarity to human electrophysiological phenotypes and disease. To identify conduction cells, we will use in situ hybridization and antibody staining of candidate markers on whole-mount and sectioned zebrafish hearts. To assess conduction system development in wild-type, mutant, and genetically altered hearts, we will use optical mapping and embryonic ECG monitoring. We will assess conduction phenotypes in erbb2 mutants, as well as in wild-type embryos injected with heart-specific dominant negative constructs designed to block other pathways involved in trabeculation. Studying the structure and function of the developing cardiac conduction system and its relationship to trabeculation will further our understanding of arrhythmia in both congenital and acquired cardiomyopathies and will provide tools and knowledge that can help treat ventricular arrhythmia and sudden death by manipulating conduction cells. PUBLIC HEALTH RELEVANCE: The experiments proposed investigate how the electrical wiring system (conduction system) of the heart develops, and whether thickening of the heart muscle during development (trabeculation) is required for the conduction system to develop properly. This work will help further our understanding of arrhythmias and sudden death in inherited heart muscle defects and acquired heart diseases.