Endothelial cell-specific regulation of the murine endothelin-1 gene

Endothelin-1 (ET-1) plays an important role in the development, physiology and pathophysiology of the cardiovascular system in mammals. ET-1 is mainly expressed in endothelial cells thus making it an attractive model for the study of transcriptional regulation in this cell type. We have previously r eported that expression of the human ET-1 gene is positively regulated by a cooperative interaction between GATA-2 and AP-1 transcription factors in c ultured endothelial cells, however these factors are not sufficient to medi ate cell type-specific expression. In vivo transcription studies of the mur ine ET-1 gene have demonstrated the presence of important cell-specific DNA elements in the 5.9 kb region upstream of the transcription initiation sit e. Using reporter gene transfection, site-directed mutagenesis and DNA-prot ein binding studies of the 5.9 kb region, we have identified a tripartite D NA element that positively regulates the expression of ET-1 specifically in cultured endothelial cells. This complex enhancer element demonstrates an endothelial cell-specific pattern of binding, suggesting that it interacts with cell-restricted regulatory factors. These findings provide important i nsights into the mechanisms that mediate the expression of ET-1 in the endo thelium and a basis for future transgenic and cloning studies aimed at iden tifying the endothelial cell-specific binding site and transcription factor (s).