Regulation of the epithelial-mesenchymal transformation through gap junction channels in heart development.

Analyses of mice lacking the gap junction protein, connexin45 (Cx45), have provided new insights into the essential roles of gap junction channels in early embryogenesis. Of great surprise is the function of Cx45 in the endothelium, where it is essential for synchronized activation of the transcription factor Nfatc1. This laterally synchronized regulation model extends the generally accepted vertical model, in which interactions between the endocardium and the myocardium induce endocardial cushion formation through the epithelial-mesenchymal transformation.