title: Regulation of human microsomal prostaglandin E synthase-1 by IL-1β requires a distal enhancer element with a unique role for C/EBPβ.
abstract: The studies of PGE2 (prostaglandin E2) biosynthesis have focused primarily on the role of cyclo-oxygenases. Efforts have shifted towards the specific PGE2 terminal synthases, particularly mPGES-1 (microsomal PGE synthase 1), which has emerged as the crucial inducible synthase with roles in pain, cancer and inflammation. mPGES-1 is induced by pro-inflammatory cytokines with studies focusing on the proximal promoter, mediated specifically through Egr-1 (early growth-response factor 1). Numerous studies demonstrate that the mPGES-1 promoter (PTGES) alone cannot account for the level of IL-1β (interleukin 1β) induction. We identified two DNase I-hypersensitive sites within the proximal promoter near the Egr-1 element and a novel distal site near -8.6 kb. Functional analysis of the distal site revealed two elements that co-operate with basal promoter expression and a stimulus-dependent enhancer. A specific binding site for C/EBPβ (CCAAT/enhancer-binding protein β) in the enhancer was directly responsible for inducible enhancer activity. ChIP (chromatin immunoprecipitation) analysis demonstrated constitutive Egr-1 binding to the promoter and induced RNA polymerase II and C/EBPβ binding to the promoter and enhancer respectively. Knockout/knockdown studies established a functional role for C/EBPβ in mPGES-1 gene regulation and the documented interaction between Egr-1 and C/EBPβ highlights the proximal promoter co-operation with a novel distal enhancer element in regulating inducible mPGES-1 expression.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Jewell N
authors.initials: JN
authors.lastname: Walters
authors.forename: Justin S
authors.initials: JS
authors.lastname: Bickford
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Newsom
authors.forename: Dawn E
authors.initials: DE
authors.lastname: Beachy
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Barilovits
authors.forename: John-David
authors.initials: JD
authors.lastname: Herlihy
authors.forename: Harry S
authors.initials: HS
authors.lastname: Nick
mesh_terms: D000818:Animals; D001483:Base Sequence; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000172:deficiency / Q000378:metabolism*; D002478:Cells, Cultured; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism*; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic; D000071876:Prostaglandin-E Synthases; D012319:RNA Polymerase II / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D053583:Interleukin-1beta; D012333:RNA, Messenger; D012319:RNA Polymerase II; D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; C000605865:Ptges protein, mouse