Molecular Mechanisms of Atrial Development and Regeneration

项目总结/摘要 先天性心脏病（CHD）是最常见的先天畸形。然而，分子 大多数CHD的病因学仍然知之甚少。此外，即使在手术后，CHD也可能导致 导致心律失常、中风和过早死亡的并发症。为了开发新的 治疗能够预防冠心病和靶向治疗特定的心血管组织，这是至关重要的， 理解指导正常心腔发育和再生的基本机制。 因此，我们实验室的长期目标是了解保守的机制，指导发展， 在脊椎动物的再生过程中使用的单个心脏腔室和腔室特异性机制。 很少有信号是已知的，需要专门指导心房的发展，与特定的调节心房 再生不被理解。本提案的具体目的是通过以下方式阐明机制： 其中同线长非编码RNA（lncRNA）家族限制Nr 2f转录因子的表达， 解读Nr 2f蛋白水平如何影响成年人发育和心房再生过程中的心房异质性 斑马鱼这项提案中的研究与人类健康有关，因为现在有许多基因组分析 表明Nr 2f 2中的突变与CHD相关，特别是人类的ASD。当Nr 2f 2敲除 小鼠和人类干细胞的体外研究揭示了心房肌细胞对Nr 2f 1和Nr 2f 2的需求。 在心房发育中，Nr 2f蛋白指导心房正常发育的机制还不完全清楚。 明白重要的是，目前还不了解调控Nr 2f的lncRNA依赖性机制 proteins.我们对一种称为as-oca的lncRNA的分析表明，在体内它抑制nr 2f 1a的翻译， 哺乳动物Nr 2f 2的功能等同物。此外，我们发现，Nr 2f 1a水平调节以前， 胚胎心房中心房心肌细胞的不均一性和心房再生。在目标1中， 我们将研究as-oca抑制nr 2f 1a翻译的具体机制以及这种机制的保守性。 NR 2F相关lncRNA家族在人类诱导多能干细胞中的作用机制。在目标2中， 将研究Nr 2f 1a和经典Wnt信号在产生心房心肌细胞中的需求 多样性和以前未识别的心房亚群的转录特征。在目标3中，我们 检测心房再生过程中心外膜的需求和心房内Nr 2f 1a的需求 心外膜由于Nr 2f转录因子在所有脊椎动物的心房发育中起保守作用， 这些研究将极大地提高我们对转录后机制的理解， 脊椎动物心房发育和心房再生过程中采用的独特机制。最终，这些 研究将积累知识的基础，可用于改善能够预防和 改善冠心病，有效修复受损心脏。

Project Summary/Abstract Congenital heart defects (CHDs) are the most common congenital malformations. However, the molecular etiology underlying most CHDs remain poorly understood. Furthermore, CHDs even following surgery can lead to complications later in life that result in arrhythmias, stroke, and premature death. In order to develop novel therapies able to prevent CHDs and target therapies to specific cardiovascular tissues, it is critical to garner understanding of fundamental mechanisms directing normal cardiac chamber development and regeneration. Therefore, long-term goals of our lab are to understand conserved mechanisms that direct the development of individual cardiac chambers and chamber-specific mechanisms utilized during regeneration in vertebrates. Few signals are known to be required that specifically direct atrial development, with specific regulators of atrial regeneration not being understood. The specific aims of this proposal are to elucidate the mechanisms by which a syntenic long non-coding RNA (lncRNA) family limits the expression of Nr2f transcription factors and decipher how Nr2f protein levels affect atrial heterogeneity during development and atrial regeneration in adult zebrafish. The studies in this proposal are relevant to human health as numerous genomic analyses now indicate that mutations in Nr2f2 are associated with CHDs, in particular ASDs in humans. While Nr2f2 knockout mice and in vitro studies with human stem cells have revealed requirements for both Nr2f1 and Nr2f2 in atrial development, the mechanisms by which Nr2f proteins direct proper atrial development are not completely understood. Importantly, there is currently no understanding of lncRNA-dependent mechanisms regulating Nr2f proteins. Our analysis of a lncRNA we call as-oca shows that in vivo it represses the translation of nr2f1a, the functional equivalent of mammalian Nr2f2. Moreover, we find that Nr2f1a levels regulate previously unrecognized heterogeneity of atrial cardiomyocytes in the embryonic atrium and atrial regeneration. In Aim 1, we will examine the specific mechanism that as-oca inhibits nr2f1a translation and the conservation of this mechanism among the NR2F-associated lncRNA family in human induced pluripotent stem cells. In Aim 2, we will examine the requirements of Nr2f1a and canonical Wnt signaling in generating atrial cardiomyocyte diversity and the transcriptional signature of a previously unrecognized atrial subpopulation. In Aim 3, we will examine the requirement of the epicardium in atrial regeneration and requirement of Nr2f1a within the atrial epicardium. Because Nr2f transcription factors play conserved roles in atrial development of all vertebrates, these studies will dramatically improve our understanding of post-transcriptional mechanisms regulating normal vertebrate atrial development and unique mechanisms employed during atrial regeneration. Ultimately, these studies will garner a foundation of knowledge that can be used to improve therapies capable of preventing and ameliorating CHDs and efficiently repairing injured hearts.