Roles of calcium and kinases in regulation of thrombin-stimulated preproendothelin-1 transcription.

Abstract

The release of the vasoactive peptide endothelin-1 (ET-1) is Ca2+ dependent after thrombin stimulation; however, little is known about the pathways involved. We studied the importance of Ca(2+)-dependent signal transduction pathways on preproET-1 mRNA induction in human endothelial cells. Thrombin-mediated preproET-1 mRNA induction was inhibited after clamping of cytosolic free CA2+ concentration ([Ca2+]i) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. Chelation of extracellular Ca2+ with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid also had a significant inhibitory effect on the induction of preproET-1 mRNA. The Ca2+ ionophore A23187 induced constitutive as well as thrombin-stimulated preproET-1 mRNA expression. Mobilization of Ca2+ stores into the cytosol by inhibition of endoplasmic reticulum Ca(2+)-adenosinetriphosphatase with thapsigargin was effective also in inducing preproET-1 mRNA. Calmodulin antagonists W-7 and calmidazolium, as well as Ca2+/calmodulin-dependent kinase II inhibitor KN-62, significantly reduced thrombin-induced preproET-1 mRNA. Inhibition by cyclosporin A of the Ca(2+)-calmodulin-dependent phosphatase calcineurin potentiated constitutive preproET-1 mRNA. These data suggest that, in human endothelial cells, thrombin-mediated preproET-1 gene induction is regulated by a stimulatory Ca2+/calmodulin kinase II-dependent pathway.