TRANSCRIPTIONAL REGULATION OF HUMAN PROSTAGLANDIN-ENDOPEROXIDE SYNTHASE-2 GENE BY LIPOPOLYSACCHARIDE AND PHORBOL ESTER IN VASCULAR ENDOTHELIAL-CELLS - INVOLVEMENT OF BOTH NUCLEAR FACTOR FOR INTERLEUKIN-6 EXPRESSION SITE AND CAMP RESPONSE ELEMENT

There exist two distinct isozymes of prostaglandin-endoperoxide syntha se (PES). PES-2 mRNA is synergistically induced by lipopolysaccharide (LPS) and 12-O-tetradecanoylphorbol-13-acetate (TPA) in bovine arteria l endothelial cells. On the other hand, PES-1 mRNA is constitutively e xpressed under these conditions. Therefore, the promoter activities of the human genes for PES-1 and -2 in bovine arterial endothelial cells were examined. The 5'-flanking region of the human PES-2 gene (nucleo tides -327 to +59) showed promoter activity inducible by LPS and TPA u sing transient transfection analysis, whereas that of the PES-1 gene ( nucleotides -1010 to +69) showed constitutive promoter activity. Destr uction of both consensus sequences for the nuclear factor responsible for the interleukin-6 expression (NF-IL6) site (nucleotides -132 to -1 24) and the cyclic AMP response element (CRE) (nucleotides -59 to -53) of the human PES-2 gene markedly reduced the promoter activity (25%) of the PES-2 gene after combined treatment with LPS and TPA, although single destruction of the NF-IL6 site or the CRE slightly reduced the promoter activity (60 or 90%, respectively). Moreover, cotransfection experiments showed that a trans-acting factor, CCAAT enhancer binding protein delta (C/EBP delta), which binds to both the NP-IL6 site and t he CRE, increased the promoter activity of the PES-2 gene mainly throu gh the CRE. C/EBP delta mRNA was rapidly induced by LPS. Collectively, these results suggest that transcription of the PES-2 gene in vascula r endothelial cells is regulated through combination of the NF-IL6 sit e and the CRE and that C/EBP delta functions as one of the trans-actin g factors.