GATA4/5/6 family transcription factors are conserved determinants of cardiac versus pharyngeal mesoderm fate

GATA4/5/6 transcription factors play essential, conserved roles in heart development. How these factors mediate the transition from multipotent mesoderm progenitors to a committed cardiac fate is unclear. To understand how GATA4/5/6 modulate cell fate decisions we labelled, isolated, and performed single-cell gene expression analysis on cells that express gata5 at pre-cardiac time points spanning gastrulation to somitogenesis. We found that most mesendoderm-derived lineages had dynamic gata5/6 expression. In the absence of Gata5/6, the population structure of mesendoderm-derived cells was dramatically altered. In addition to the expected absence of cardiac mesoderm, we observed a concomitant expansion of cranial-pharyngeal mesoderm. Functional genetic analyses in zebrafish and the invertebrate chordate Ciona, which possess a single GATA4/5/6 homolog, revealed an essential and cell-autonomous role for GATA4/5/6 in promoting cardiac and inhibiting pharyngeal mesoderm identity. Overall, the maintenance and repression of GATA4/5/6 activity plays a critical, evolutionarily conserved role in early development.