Mechanisms governing the differentiation and maintenance of atrial identity

项目概要/摘要 所有器官的正常发育都需要适当的分化和细胞特性的维持。 在心脏中，维持心肌细胞身份所必需的基因突变与 结构性先天性心脏缺陷，这是新生儿最常见的畸形。尽管他们的 尽管频率高，但大多数先天性心脏病的病因仍知之甚少。此外，众多 结构性先天性心脏病与心律失常有关。尽管手术技术不断进步 已成功让患者存活至成年，但手术不能修复心律失常 与结构缺陷有关。因此，有必要了解指导的基本机制 正常脊椎动物心脏发育，以便让我们了解先天性心脏缺陷的病因及其 相关心律失常。我们实验室的长期目标是了解保守的分子和遗传 在脊椎动物早期发育过程中指导心室大小的机制。 Nr2f转录因子 在脊椎动物心脏发育中具有高度保守的要求。此外，Nr2f 基因突变 人类与一系列先天性心脏病有关，包括房间隔缺损。这个提议 将通过研究 Nr2f 依赖性来研究确定心房大小的基本机制 控制心房心肌细胞分化和维持心房心肌细胞身份的机制。 虽然心房发育对 Nr2f 因子的要求已明确，但控制 Nr2f 的机制 心房心肌细胞中的基因表达以及 Nr2f 转录因子如何指导心房心肌细胞 发展仍然知之甚少。我们的工作表明斑马鱼 Nr2f1a 是功能等同物 Nr2f2 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，它足以 促进斑马鱼心房心肌细胞中 Nr2f1a 的表达，并且 Nr2f1a 具有以前未被识别的功能 要求同时维持心房心肌细胞并抑制起搏器的获得 心肌细胞的身份。在目标 1 中，我们将询问调节保守的 nr2f1a 顺式调节的信号 促进心房心肌细胞表达的增强剂。在目标 2 中，我们将确定时间要求 nr2f1a 的变化和 nr2f1a 突变体心房内心肌细胞的分化状态。在目标 3 中，我们将 阐明抑制静脉中起搏器心肌细胞身份的 Nr2f 依赖性基因调控网络 心房。我们的研究可能为我们了解先天性心脏病的病因提供基础信息 缺陷及其相关的心律失常，最终可能会导致新的疗法可以预防或 改善人类先天性心脏病和相关心律失常。

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.