Cardiac TranscriptionFactor Interactomes regulating cardiac development&Reprogram

信号传导、转录和转录后事件在早期心脏发生过程中调节心脏细胞的命运决定。这些事件的中断可能导致先天性心脏畸形。特别是，转录因子如GATA 4、TBX 5、NKX 2 -5和NOTCHI的人类突变导致儿童心脏病。胚胎途径在成年心脏的应激下被重新激活，其中GATA 4和MEF 2C在心脏肥大期间的转录反应中发挥核心作用。最近的研究强调了蛋白质-蛋白质相互作用（PPI）在决定DNA结合转录因子的转录输出中的重要性。然而，滴定心脏转录因子效应的复杂PPI尚未得到系统研究。在PPG的上一个资助期间，我们的发现集中在心脏发育过程中Notch和Wnt信号通路成员之间的PPI。此外，我们报告了心脏发育转录因子的组合，包括Gata 4，Mef 2c和Tbx 5，可以在成人中将非肌肉细胞重编程为新的心肌细胞样细胞，导致损伤后的心脏再生; Hand 2的加入进一步改善了重编程。本PPG更新申请的项目1将测试以下假设：Gata 4、Mef 2c、Tbx 5和Hand 2彼此之间以及与其他关键因子之间具有复杂的相互作用，以调节心脏分化和心脏重编程期间的转录输出。本研究的主要目的是（1）建立小鼠胚胎干细胞向心肌细胞分化过程中Gata 4、Mef 2c、Tbx 5和Hand 2相互作用基因组的图谱，（2）确定相互作用基因组对Gata 4、Tbx 5和Hand 2的中枢依赖性，以及GATA 4中致病性错义突变对相互作用基因组的影响;以及（3）确定涉及Gata 4、Mef 2c、Tbx 5和Hand 2的PPI在特定基因组位点上的功能后果，并将PPI与心脏分化和重编程期间转录因子的基因组占用整合。该项目将揭示心脏基因调控的潜在机制，并将提供潜在的干预点，以积极或消极地滴定转录活性。

Signaling, transcriptional, and post-transcriptional events regulate cardiac cell fate decisions during early cardiogenesis. Disruption of such events can lead to congenital heart malformations. In particular, human mutations in transcription factors, such as GATA4, TBX5, NKX2-5 and NOTCHI, result in heart disease in children. Embryonic pathways are reactivated under stress in adult hearts, with GATA4 and MEF2C playing central roles in the transcripfional response during cardiac hypertrophy. Recent studies highlight the importance of protein-protein interactions (PPI) in dictating the transcripfional output of DNA binding transcription factors. However, the complex PPIs that titrate effects of cardiac transcription factors have not been systematically explored. During the previous funding period of this PPG, our discoveries focused on PPIs between members ofthe Notch and Wnt signaling pathways during cardiac development. In addition, we reported that a combination of cardiac developmental transcription factors, including Gata4, Mef2c and Tbx5, could reprogram non-muscle cells into new cardiomyocyte-like cells in the adult, resulting in cardiac regeneration after injury; the addition of Hand2 further improves reprogramming. Project 1 of this PPG renewal application will test the hypothesis that Gata4, Mef2c, Tbx5, and Hand2 have complex interactions with one another and other key factors to regulate the transcripfional output during cardiac differentiation and cardiac reprogramming. The specific alms are (1) to develop a comprehensive map ofthe Interactome involving Gata4, Mef2c, Tbx5 and Hand2 during cardiac differentiation of mouse embryonic stem (ES) cells into cardiomyocytes; (2) determine the central dependency of interactomes on Gata4, Tbx5 and Hand2, and the consequences of disease-causing missense mutations In GATA4 on the interactome; and (3) determine the functional consequences of PPIs involving Gata4, Mef2c, Tbx5 and Hand2 on specific genomic loci and integrate PPIs with genome occupancy ofthe transcription factors during cardiac differentiation and reprogramming. This project will reveal mechanisms underlying cardiac gene regulation and will provide potential points of intervention to positively or negatively titrate transcriptional activity.