CHARACTERIZATION AND FUNCTIONAL-ANALYSIS OF THE RAT ENDOTHELIN-1 PROMOTER

To define the molecular mechanisms of endothelin-1 (ET-1) gene regulation, we cloned, sequenced, and characterized the rat ET-1 promoter. A sequence consisting of the first 1329 bp of the rat ET-1 promoter was investigated in greater detail. Sequence analysis identified putative binding sites for a number of transcriptional factors that may be involved in ET-1 gene regulation. Several of these factors have been proposed earlier to be involved in cell-specific gene regulation and may be responsible for directing ET-1 expression in vivo. For functional analysis of the ET-1 promoter, we generated a reporter gene construct using luciferase as reporter gene under control of the promoter fragment isolated. The construct was transfected transiently into bovine aortic endothelial cells, and luciferase expression was evaluated. The results indicated that the promoter segment used showed high expression in endothelial cells comparable to that induced by viral promoters. Since ET-1 is regulated by a number of vasoactive substances, we studied the effect of angiotensin II on endothelin transcription. We could demonstrate a dose-dependent transcriptional activation of ET-1 transcription by angiotensin.