The earliest step of vertebrate heart development occurs during gastrulation when dorsoanterior endoderm is believed to signal to adjacent mesoderm to induce it to adopt a cardiac fate. By using an explant assay to investigate this early step in cardiac induction, Latinkić et al. have now discovered that misexpressing the cardiac gene-inducing transcription factor GATA4 in Xenopus ectodermal explants results in cardiac marker-gene expression and cardiomyocyte differentiation. Surprisingly,cardiac induction occurs independently of endoderm and even once ectoderm has started differentiating into epidermal tissue (see p. 3865). Neither one of two key pathways that regulate cardiac specification – the BMP and non-canonical WNT pathways – appear to be required for the inductive activities of GATA4 here. Whether these findings reflect an endogenous role for GATA4, perhaps acting through an as-yet-unidentified cardiogenic pathway,remains to be resolved.

You do not currently have access to this content.