Abstract
Congenital heart defects can be caused by mutations in genes that guide cardiac lineage formation. Here, we show deletion of NKX2-5, a critical component of the cardiac gene regulatory network, in human embryonic stem cells (hESCs), results in impaired cardiomyogenesis, failure to activate VCAM1 and to downregulate the progenitor marker PDGFRα. Furthermore, NKX2-5 null cardiomyocytes have abnormal physiology, with asynchronous contractions and altered action potentials. Molecular profiling and genetic rescue experiments demonstrate that the bHLH protein HEY2 is a key mediator of NKX2-5 function during human cardiomyogenesis. These findings identify HEY2 as a novel component of the NKX2-5 cardiac transcriptional network, providing tangible evidence that hESC models can decipher the complex pathways that regulate early stage human heart development. These data provide a human context for the evaluation of pathogenic mutations in congenital heart disease.
Highlights
Congenital heart defects can be caused by mutations in genes that guide cardiac lineage formation
Cardiac cells derived from NKX2-5−/− human embryonic stem cells (hESCs) expressed GFP (Fig. 1b), but did not produce NKX2-5 protein whereas NKX2-5 levels were comparable between NKX25eGFP/w and wildtype cells (Supplementary Fig. 1f)
Since the majority of cardiomyocytes obtained in monolayer differentiations of wildtype hPSCs display an early embryonic ventricular phenotype we focused on HEY2 and IRX4 as they have known roles in murine ventricular myogenesis[27,39,41,42,43,44,45,46,47]
Summary
Congenital heart defects can be caused by mutations in genes that guide cardiac lineage formation. Molecular profiling and genetic rescue experiments demonstrate that the bHLH protein HEY2 is a key mediator of NKX2-5 function during human cardiomyogenesis. These findings identify HEY2 as a novel component of the NKX2-5 cardiac transcriptional network, providing tangible evidence that hESC models can decipher the complex pathways that regulate early stage human heart development. These data provide a human context for the evaluation of pathogenic mutations in congenital heart disease. Genetic rescue experiments show that HEY2 restores, in part, the cardiac muscle genetic program in NKX2-5 null cardiomyocytes
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