The conserved role and divergent regulation of foxa, a pan-eumetazoan developmental regulatory gene

► Foxa controls mesenchymal-to-epithelial transition during gut formation in sea urchin. ► Foxa orthologs control similar processes in various tissues in mouse and C. elegans. ► foxa transcriptional regulation had diverged between sea urchin and C. elegans. ► We suggest that Foxa had a role in an ancestral shallow gene regulatory network. ► This network controlled mesenchymal-to-epithelial transition during gut formation. ► Evolutionary changes of foxa regulation activated this network in novel embryonic addresses.