Conversion of fibroblasts into functional cardiomyocytes represents a potential means of restoring cardiac function after myocardial infarction, but so far this process remains inefficient and little is known about its molecular mechanisms. Here we show that DAPT, a classical Notch inhibitor, enhances the conversion of mouse fibroblasts into induced cardiac-like myocytes by the transcription factors GATA4, HAND2, MEF2C, and TBX5. DAPT cooperates with AKT kinase to further augment this process, resulting in up to 70% conversion efficiency. Moreover, DAPT promotes the acquisition of specific cardiomyocyte features, substantially increasing calcium flux, sarcomere structure, and the number of spontaneously beating cells. Transcriptome analysis shows that DAPT induces genetic programs related to muscle development, differentiation, and excitation-contraction coupling. Mechanistically, DAPT increases binding of the transcription factor MEF2C to the promoter regions of cardiac structural genes. These findings provide mechanistic insights into the reprogramming process and may have important implications for cardiac regeneration therapies.

成纤维细胞向功能性心肌细胞的转化代表心肌梗死后恢复心脏功能的一种潜在手段，但到目前为止，该过程仍然效率低下，对其分子机制了解甚少。在这里，我们显示经典的Notch抑制剂DAPT通过转录因子GATA4，HAND2，MEF2C和TBX5增强了小鼠成纤维细胞向诱导的心脏样心肌细胞的转化。DAPT与AKT激酶合作，进一步增强了这一过程，转化效率高达70％。而且，DAPT促进了特定心肌细胞功能的获取，大大增加了钙通量，肌节结构和自发搏动细胞的数量。转录组分析表明，DAPT可以诱导与肌肉发育，分化，和激励-收缩耦合。从机理上讲，DAPT增加了转录因子MEF2C与心脏结构基因启动子区域的结合。这些发现为重编程过程提供了机械方面的见识，并且可能对心脏再生疗法产生重要影响。