Modular regulation of cGATA-5 gene expression in the developing heart and gut

The evolutionarily conserved GATA-5 transcription factor is an early and pe rsistent marker of heart and gut development in diverse vertebrate species. To search for control regions that might regulate the chicken GATA-5 (cGAT A-5) gene, we assayed a set of cGATA-5/lacZ constructs in transgenic mice a nd found evidence for two functionally conserved control regions that regul ate different facets of cGATA-5 gene expression. The more distal control re gion is activated in embryonic endoderm at the head-fold stage, whereas the other control region contains a regulatory module that is activated in a r estricted region of endoderm following closure of the gut tube. Remarkably, the latter control region also contains a complex regulatory module that i s activated in the cardiac crescent at the head-fold stage and subsequently functions in several mesodermal components of the developing heart, includ ing the outer (epicardial) layer. We discuss these results in terms of poss ible contributions of epicardial-derived cells to the formation of heart va lves, conduction tissue, and compact myocardium. These transgenes thus reve al, and provide a means to further analyze, transcriptional programs for se veral facets of heart morphogenesis and gut development. (C) 2000 Academic Press.