Endothelial Expression of Endothelin-Converting Enzyme-1β mRNA Is Regulated by the Transcription Factor Ets-1

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Abstract
Cleavage of big endothelins (ETs) by endothelin-converting enzymes (ECEs) represents the final step in the biosynthesis of ETs. ECE-1 is expressed predominantly in endothelial cells and exists in two isoforms, termed alpha and beta, differing in their 5' termini. We have recently shown that isoform-specific mRNA expression is directed by alternative promoters. To investigate possible mechanisms of transcriptional regulation of ECE-1, we stimulated E.A. hy 926 cells with phorbol ester and found a greater than threefold increase in ECE-1 beta mRNA at 12-24 h of stimulation. Because the beta-specific promoter is characterized by multiple consensus sequences for transcription factors of the ETS family, Ets-1 and PEA3, we also analyzed Ets-1 mRNA expression and found at least a fivefold increase in Ets-1 mRNA at 3 h of phorbol ester stimulation. Gel shift analysis revealed a specific interaction of nuclear proteins isolated from E.A. hy 926 cells with an oligonucleotide harboring the Ets-1 consensus sequence. Using a specific anti-Ets-1 antibody, we detected a supershifted band indicating the expression of Ets-1 protein in E.A. hy 926 cells. We conclude that Ets-1 is involved in transcriptional upregulation of ECE-1 beta mRNA in E.A. hy 926 cells induced by phorbol ester.