title: NF-κB-dependent IL-8 induction by prostaglandin E(2)  receptors EP(1)  and EP(4).
abstract: OBJECTIVE
  Recent studies suggested a role for PGE(2)  in the expression of the chemokine IL-8. PGE(2)  signals via four different GPCRs, EP(1) -EP(4) . The role of EP(1)  and EP(4)  receptors for IL-8 induction was studied in HEK293 cells, overexpressing EP(1)  (HEK-EP(1) ), EP(4)  (HEK-EP(4) ) or both receptors (HEK-EP(1)  + EP(4) ).
  
  
  METHODS
  IL-8 mRNA and protein induction and IL-8 promoter and NF-κB activation were assessed in EP expressing HEK cells.
  
  
  RESULTS
  In HEK-EP(1)  and HEK-EP(1)  + EP(4)  but not HEK or HEK-EP(4)  cells, PGE(2)  activated the IL-8 promoter and induced IL-8 mRNA and protein synthesis. Stimulation of HEK-EP(1)  + EP(4)  cells with an EP(1) -specific agonist activated IL-8 promoter and induced IL-8 mRNA and protein, whereas a specific EP(4)  agonist neither activated the IL-8 promoter nor induced IL-8 mRNA and protein synthesis. Simultaneous stimulation of HEK- EP(1)  + EP(4)  cells with both agonists activated IL-8 promoter and induced IL-8 mRNA to the same extent as PGE(2) . In HEK-EP(1)  + EP(4)  cells, PGE(2) -mediated IL-8 promoter activation and IL-8 mRNA induction were blunted by inhibition of IκB kinase. PGE(2)  activated NF-κB in HEK-EP(1) , HEK-EP(4)  and HEK-EP(1)  + EP(4)  cells. In HEK-EP(1)  + EP(4)  cells, simultaneous activation of both receptors was needed for maximal PGE(2) -induced NF-κB activation. PGE(2) -stimulated NF-κB activation by EP(1)  was blocked by inhibitors of PLC, calcium-signalling and Src-kinase, whereas that induced by EP(4)  was only blunted by Src-kinase inhibition.
  
  
  CONCLUSIONS
  These findings suggest that PGE(2) -mediated NF-κB activation by simultaneous stimulation of EP(1)  and EP(4)  receptors induces maximal IL-8 promoter activation and IL-8 mRNA and protein induction.
authors.affiliation: Institut für Ernährungswissenschaft, Universität Potsdam, Nuthetal, Germany. fneusch@uni-potsdam.de
authors.forename: F
authors.initials: F
authors.lastname: Neuschäfer-Rube
authors.forename: A
authors.initials: A
authors.lastname: Pathe-Neuschäfer-Rube
authors.forename: S
authors.initials: S
authors.lastname: Hippenstiel
authors.forename: M
authors.initials: M
authors.lastname: Kracht
authors.forename: G P
authors.initials: GP
authors.lastname: Püschel
mesh_terms: D015232:Dinoprostone / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D058306:Receptors, Prostaglandin E, EP1 Subtype / Q000235:genetics / Q000378:metabolism*; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D016209:Interleukin-8; D016328:NF-kappa B; D012333:RNA, Messenger; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D015232:Dinoprostone