Regulation of protease-activated receptor-1 by vasodilatory prostaglandins via NFAT.
OBJECTIVE
We recently reported that prostacyclin suppresses protease-activated receptor-1 (PAR-1) in human vascular smooth muscle cells (VSMC) via cyclic AMP and protein kinase A. This study examines the downstream mechanisms, particularly the role of nuclear factor of activated T-cells (NFAT).


RESULTS
Human saphenous vein VSMC were exposed to phorbol 12-myristate 13-acetate (PMA) to induce endogenous cyclooxygenase-2-dependent prostaglandin generation. This was found to attenuate PAR-1 expression; similar suppression was seen with the EP2-prostaglandin receptor agonist butaprost. Stimulation of the 'exchange protein directly activated by cyclic AMP' (EPAC) was without effect. The NFAT inhibitor cyclosporin A (CsA) or NFAT2 siRNA both reduced PAR-1 mRNA and protein expression and prevented the stimulatory effects of thrombin or PAR-1 activating peptide (TFLLRN) on ERK1/2 phosphorylation and interleukin-6 expression. CsA or mutation of the NFAT binding motif in the PAR-1 promoter also blunted PAR-1 promoter activity (luciferase reporter assay). These inhibitory actions of CsA were comparable to those of the prostacyclin-mimetic iloprost, and both CsA and iloprost similarly attenuated nuclear NFAT2 localization and binding to the PAR-1 promoter (chromatin immunoprecipitation assay).


CONCLUSIONS
This study provides the first evidence that NFAT2 contributes to the transcriptional control of PAR-1 in human VSMC and that PKA-dependent NFAT2 inhibition represents a mechanism by which vasodilatory prostaglandins regulate the vascular actions of thrombin.
Rosenkranz
Anke C
AC
Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.
Rauch
Bernhard H
BH
Freidel
Kerstin
K
Schrör
Karsten
K
D001483:Base Sequence; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011453:Prostaglandins / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D044463:Receptor, PAR-1 / Q000235:genetics / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D014158:Transcription, Genetic; D014664:Vasodilation / Q000502:physiology*
C508600:IL6 protein, human; D015850:Interleukin-6; D050778:NFATC Transcription Factors; C494003:NFATC1 protein, human; D009842:Oligopeptides; D011453:Prostaglandins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D044463:Receptor, PAR-1; C508781:threonyl-phenylalanyl-leucyl-leucyl-arginyl-asparagine; D016572:Cyclosporine; D004247:DNA; D013917:Thrombin; D016285:Iloprost; D013755:Tetradecanoylphorbol Acetate