Mechanisms governing the differentiation and maintenance of atrial identity

项目概要/摘要 细胞特性的适当分化和维持是所有器官正常发育所必需的。 在心脏中，维持心肌细胞特性所必需的基因突变与 结构性先天性心脏缺陷，这是新生儿中最常见的畸形。尽管他们 尽管先天性心脏病的发病率很高，但大多数先天性心脏病的病因仍然知之甚少。此外，许多 结构性先天性心脏缺陷与心律失常有关。尽管外科技术的进步 虽然已经成功地让患者存活到成年，但手术并不能修复心律失常 与结构缺陷有关。因此，理解指导人类行为的基本机制是至关重要的。 正常脊椎动物心脏发育，以便让我们了解先天性心脏缺陷及其病因 相关性心律失常我们实验室的一个长期目标是了解保守的分子和遗传 在早期脊椎动物发育过程中指导心腔大小的机制。Nr 2f转录因子 在脊椎动物心脏发育中有高度保守的需求。此外，Nr 2f基因的突变， 人类与一系列的先天性心脏缺陷有关，包括心房间隔缺陷。这项建议 将通过研究Nr 2f依赖性， 控制心房心肌细胞分化和维持心房心肌细胞特性的机制。 虽然在心房发育中对Nr 2f因子的需求是明确的，但控制Nr 2f的机制 心房肌细胞基因表达及Nr 2f转录因子对心房肌细胞的调控作用 发展仍然知之甚少。我们的工作表明，斑马鱼Nr 2f 1a是功能等同物， Nr 2f 2在心房发育中的作用我们的初步数据已经确定了一个保守的增强子，足以 促进斑马鱼心房心肌细胞中Nr 2f 1a表达，且Nr 2f 1a具有先前未被认识的 要求同时维持心房心肌细胞和抑制起搏点获得 心肌细胞特性。在目的1中，我们将询问调节保守的nr 2f 1a顺式调节的信号。 促进心房心肌细胞表达的增强子。在目标2中，我们将确定时间要求 和nr 2f 1a突变体心房心肌细胞的分化状态。在目标3中，我们 阐明Nr 2f依赖的基因调控网络，抑制起搏心肌细胞的身份，在静脉 心房我们的研究为我们了解先天性心脏病的病因提供了基础资料 缺陷及其相关的心律失常，这最终可能导致新的疗法，可以预防或 改善人类先天性心脏缺陷和相关的心律失常。

Project Summary/Abstract Appropriate differentiation and maintenance of cellular identity are required for normal development of all organs. In the heart, mutations in genes that are necessary to maintain cardiomyocyte identity are associated with structural congenital heart defects, which are the most common malformations found in newborns. Despite their frequency, the etiology of most congenital heart defects remains poorly understood. Furthermore, numerous structural congenital heart defects are associated with arrythmias. Although advances in surgical techniques have been successful in allowing patients to survive to adulthood, the surgeries do not repair arrythmias associated with the structural defects. Thus, it is essential to understand fundamental mechanisms directing normal vertebrate heart development, in order to inform us of the etiology of congenital heart defects and their associated arrythmias. A long-term goal of our lab is to understand the conserved molecular and genetic mechanisms that direct cardiac chamber size during early vertebrate development. Nr2f transcriptions factors have highly conserved requirements in vertebrate heart development. Furthermore, mutations in Nr2f genes in humans are associated with a spectrum of congenital heart defects, including atrial septal defects. This proposal will investigate fundamental mechanisms determining atrial chamber size through investigating Nr2f-dependent mechanisms controlling atrial cardiomyocyte differentiation and the maintenance of atrial cardiomyocyte identity. While requirements for Nr2f factors are well-established in atrial development, the mechanisms controlling Nr2f gene expression in atrial cardiomyocytes and by which Nr2f transcription factors direct atrial cardiomyocyte development remain poorly understood. Our work has shown that zebrafish Nr2f1a is the functional equivalent of Nr2f2 in atrial development. Our preliminary data has identified a conserved enhancer that that is sufficient to promote Nr2f1a expression in atrial cardiomyocytes zebrafish and that Nr2f1a has a previously unrecognized requirement concurrently maintaining atrial cardiomyocyte and inhibiting the acquisition of pacemaker cardiomyocyte identity. In Aim 1, we will interrogate the signals that regulate the conserved nr2f1a cis-regulatory enhancer that promotes atrial cardiomyocyte expression. In Aim 2, we will determine the temporal requirements of nr2f1a and the differentiation state of cardiomyocytes within the atria of nr2f1a mutants. In Aim 3, we will elucidate the Nr2f-dependent gene regulatory networks that repress pacemaker cardiomyocyte identity in venous atria. Our studies may provide a foundation of information that may inform us of the etiology of congenital heart defects and their associated arrythmias, which ultimately may lead to novel therapies that can prevent or ameliorate congenital heart defects and associated arrythmias in humans.