Engineering effector domains of MEF2C and GATA4 enhances cardiac reprogramming

The transcription factors MEF2C, GATA4, and TBX5 (MGT) are well established for converting fibroblasts into induced cardiomyocytes (iCMs). However, these reprogramming factors contain effector domains, yet their functional roles in cardiac reprogramming remain largely uncharacterized. Furthermore, whether internal deletions of these domains improve or compromise reprogramming efficiency has not been elucidated. Here we found that the combination of MEF2C and GATA4 mutants (MΔGΔT) elevated reprogramming efficiency by 7-fold to ~21%, achieving robust induction of iCMs with well-defined sarcomeric structures. MEFs were transduced with the retrovirus (MGT, MΔGΔT) as indicated. Cells were collected after 1 week.