title: Involvement of PGE2 and the cAMP signalling pathway in the up-regulation of COX-2 and mPGES-1 expression in LPS-activated macrophages.
abstract: PG (prostaglandin) E2 plays an important role in the modulation of the immune response and the inflammatory process. In the present study, we describe a PGE2 positive feedback for COX (cyclo-oxygenase)-2 and mPGES-1 [microsomal PGES (PGE synthase)-1] expression in the macrophage cell line RAW 264.7. Our results show that PGE2 induces COX-2 and mPGES-1 expression, an effect mimicked by dbcAMP (dibutyryl-cAMP) or forskolin. Furthermore, the cAMP signalling pathway co-operates with LPS (lipopolysaccharide) in the induction of COX-2 and mPGES-1 transcriptional activation. Analysis of the involvement of PGE receptors [EPs (E-prostanoids)] showed that incubation with EP2 agonists up-regulated both COX2 and mPGES-1 mRNA levels. Moreover, EP2 receptor overexpression enhanced the transcriptional activation of COX2 and mPGES-1 promoters. This induction was repressed by the PKA (protein kinase A) inhibitor H89. Activation of the PGE2/EP2/PKA signalling pathway induced the phosphorylation of CREB [CRE (cAMP-response element)-binding protein] in macrophages and stimulated the specific binding of this transcription factor to COX2 and mPGES-1 promoters. Deletion or mutation of potential CRE sites in both promoters diminished their transcriptional activity. In summary, the results of the present study demonstrate that activation of PKA/CREB signalling through the EP2 receptor by PGE2 plays a key role in the expression of COX-2 and mPGES-1 in activated macrophages.
authors.affiliation: Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Manuel D
authors.initials: MD
authors.lastname: Díaz-Muñoz
authors.forename: Inés C
authors.initials: IC
authors.lastname: Osma-García
authors.forename: Manuel
authors.initials: M
authors.lastname: Fresno
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Iñiguez
mesh_terms: D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism*; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D011401:Promoter Regions, Genetic; D000071876:Prostaglandin-E Synthases; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: D008070:Lipopolysaccharides; D000242:Cyclic AMP; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; C000605865:Ptges protein, mouse; D015232:Dinoprostone