The zinc finger proteins Pannier and GATA4 function as cardiogenic factorsin Drosophila

The regulation of cardiac gene expression by GATA zinc finger transcription factors is well documented in vertebrates. However, genetic studies in mic e have failed to demonstrate a function for these proteins in cardiomyocyte specification. In Drosophila, the existence of a cardiogenic GATA factor h as been implicated through the analysis of a cardial cell enhancer of the m uscle differentiation gene D-mef2. We show that the GATA gene pannier is ex pressed in the dorsal mesoderm and required for cardial cell formation whil e repressing a pericardial cell fate. Ectopic expression of Pannier results in cardial cell overproduction, while co-expression of Pannier and the hom eodomain protein Tinman synergistically activate cardiac gene expression an d induce cardial cells. The related GATA4 protein of mice likewise function s as a cardiogenic factor in Drosophila, demonstrating an evolutionarily co nserved function between Pannier and GATA4 in heart development.