The Role of RERE in Congenital Cardiac Anomalies

描述（由申请人提供）：我们的长期目标是了解疾病基因破坏正常心血管发育和功能的分子机制。心血管畸形和心肌病是世界范围内发病率和死亡率的主要原因，在1:50 000新生儿中特别常见，这些新生儿有1p36染色体末端或间质性缺失。染色体1p36上导致这些心脏相关问题的剂量敏感基因尚未完全阐明。精氨酸-谷氨酸二肽（RE）重复基因（RERE）位于1p36的关键区域，与心血管畸形和心肌病的发生有关。RERE是一种心脏表达的核受体共调节因子，通过与NR2F2的相互作用正向调节视黄酸信号。在C57BL/6背景下，我们发现rre缺陷胚胎有主动脉弓异常、双出口右心室、大动脉转位和膜周围室间隔缺损。我们随后证明，在瓣膜、室间隔、主动脉弓和流出道发育过程中，Rere基因与视黄酸应答转录因子编码基因gata4相互作用。在我们的第一个具体目标中，我们将确定Rere和Gata4是否在心内膜中遗传相互作用以影响房室（AV）瓣膜间隔复合体的发育。这将通过分析使用转基因Tie2-Cre在心内膜靶向Rere和Gata4的小鼠后代来完成。我们还将使用相同的转基因Tie2-Cre切除心内膜中的Rere，以确定这些细胞中Rere的表达是否需要正常的房室瓣隔发育。这些实验尤其重要，因为瓣膜和间隔异常是由1p36基因缺失和GATA4基因突变引起的最常见的心血管畸形。在BL6/129S6基因背景下，rre缺陷小鼠没有心血管畸形，但会自发发展为心脏纤维化和心脏肥厚。这与RERE作为视黄酸信号的正调节因子的作用是一致的，视黄酸信号通过其在心肌细胞中的作用抑制心肌纤维化和心肌肥大。然而，使用传统的基因敲除模型，我们无法消除系统性RERE缺乏对这些缺陷发展的潜在影响。为了克服这个问题，我们使用转基因Myh6- Cre在混合背景下产生心肌细胞特异性rre敲除小鼠。在我们的第二个具体目标中，我们将使用这些小鼠来确定RERE对基线心功能和心脏对压力过载的反应的细胞自主作用。这些研究将为开发和测试新的预防和治疗策略奠定基础，以帮助受心血管畸形和心肌病影响的个体。这些研究还将产生用于临床干预测试的小鼠模型。

DESCRIPTION (provided by applicant): Our long-term goal is to understand the molecular mechanisms by which disease genes disrupt normal cardiovascular development and function. Cardiovascular malformations and cardiomyopathy are major causes of morbidity and mortality world-wide and are particularly common among the 1:5000 newborns that have terminal or interstitial deletions of chromosome 1p36. The dosage-sensitive genes on chromosome 1p36 that contribute to these cardiac-related problems have yet to be fully elucidated. The arginine-glutamic acid dipeptide (RE) repeats gene (RERE) is located in a critical region of 1p36 associated with the development of cardiovascular malformations and cardiomyopathy. RERE is a cardiac-expressed nuclear receptor coregulator which positively regulates retinoic acid signaling through its interaction with NR2F2. We have shown that RERE-deficient embryos have aortic arch anomalies, double outlet right ventricle, transposition of the great arteries and perimembranous ventricular septal defects on a C57BL/6 background. We subsequently demonstrated that Rere interacts genetically with Gata4-a retinoic acid-responsive transcription factor encoding gene-during valvular, septal, aortic arch and outflow tract development. In our first specific aim, we will determine if Rere and Gata4 interact genetically in the endocardium to affect the development of the atrioventricular (AV) valvuloseptal complex. This will be accomplished by analyzing the progeny of mice in which Rere and Gata4 have been targeted in the endocardium using a transgenic Tie2-Cre. We will also ablate Rere in the endocardium using the same transgenic Tie2-Cre to determine if expression of RERE in these cells is required for normal AV valvuloseptal development. These experiments are particularly important since valvular and septal anomalies are the most common cardiovascular malformations caused by 1p36 deletions and mutations in GATA4. On a BL6/129S6 background, RERE-deficient mice do not have cardiovascular malformations but spontaneously develop cardiac fibrosis and cardiac hypertrophy. This is consistent with RERE's role as a positive regulator of retinoic acid signaling, which suppresses cardiac fibrosis and myocardial hypertrophy through its actions in cardiomyocytes. However, we cannot eliminate the potential impact of systemic RERE deficiency in the development of these defects using traditional knockout models. To overcome this problem, we generated cardiomyocyte-specific Rere-knockout mice on a mixed background using a transgenic Myh6- Cre. In our second specific aim, we will use these mice to determine RERE's cell-autonomous effects on baseline cardiac function and the heart's response to pressure overload. These studies will lay the foundation from which novel preventative and therapeutic strategies can be developed and tested to help individuals affected by cardiovascular malformations and cardiomyopathy. These studies will also generate mouse models in which clinical interventions can be tested.