Molecular mechanisms of direct cardiac reprogramming

 描述(申请人提供)：诱导心肌细胞(ICM)的细胞重编程有望成为治疗心力衰竭的一种新疗法，心力衰竭是一种常见的病态疾病，由功能心肌细胞(CMS)不可逆转的丧失引起。我们和其他人已经证明，在急性心肌梗死小鼠模型中，三种转录因子Gata4、MEF2C和Tbx5的传递将内源性心脏成纤维细胞转化为功能性ICM。这些ICM与周围心肌电和机械结合，结果减少了疤痕大小，改善了心功能。这些发现表明，ICM重新编程可能是一种有希望的新方法，可以在体内为心脏病患者再生功能性CMS。然而，我们对ICM重编程的潜在分子机制的了解有限，大大阻碍了其临床应用。在这个提案中，我们将利用我们在ICM重新编程方面的专业知识、发育生物学方面的知识、我们构建的独特的新工具来定义如何在非CM细胞中建立CM命运的分子机制，而不需要通过传统的发育CM规范和分化路线。基于我们的初步数据，我们假设重编程因子Gata4、MeF2C和Tbx5以化学计量和时间协调的方式作用于CFs的一个“特权”亚群，以克服主要的表观遗传障碍(S)，并诱导CM的命运。这项提案的成功完成将确定分子组成，并确定ICM重新编程的最佳条件。我们的研究将对心脏细胞命运获得和细胞可塑性调节的基本分子机制提供新的见解。

 DESCRIPTION (provided by applicant): Cellular reprogramming of induced cardiomyocytes (iCMs) holds promise as a novel therapy for the treatment of heart failure, a common and morbid disease that is caused by irreversible loss of functional cardiomyocytes (CMs). We and others have showed that in a murine model of acute myocardial infarction, delivery of three transcription factors, Gata4, Mef2c and Tbx5, converted endogenous cardiac fibroblasts into functional iCMs. These iCMs integrated electrically and mechanically with surrounding myocardium, resulting in a reduction in scar size and an improvement in heart function. These findings suggest that iCM reprogramming might be a promising novel approach to regenerate functional CMs in vivo for patients with heart disease. However, our limited understanding of the underlying molecular mechanisms of iCM reprogramming has significantly hindered its clinical applicability. In this proposal, we will take advantage of our expertise in iCM reprogramming, knowledge in developmental biology, unique new tools that we have built to define the molecular mechanisms of how a CM fate is established in a non-CM cell without transiting through the traditional developmental CM specification and differentiation route. Based on our preliminary data, we hypothesize that reprogramming factors Gata4, Mef2c and Tbx5 act in a stoichiometrically and temporally coordinated fashion upon a "privileged" subpopulation of CFs to overcome major epigenetic barrier(s) and induce CM fate. Successful completion of this proposal will define the molecular components and determine the optimal condition for iCM reprogramming. Our studies will provide novel insights into fundamental molecular mechanisms underlying cardiac cell fate acquisition and cell plasticity regulation.