title: Deletion of microsomal prostaglandin E2 (PGE2) synthase-1 reduces inducible and basal PGE2 production and alters the gastric prostanoid profile.
abstract: Microsomal prostaglandin E synthase-1 (mPGES-1) is an inducible protein recently shown to be an important source of inflammatory PGE2. Here we have used mPGES-1 wild type, heterozygote, and null mice to assess the impact of reduction or absence mPGES-1 protein on the production of PGE2 and other prostaglandins in lipopolysaccharide (LPS)-treated macrophages and mice. Thioglycollate-elicited peritoneal macrophages with mPGES-1 deficiency were found to lose their ability to produce PGE2 upon LPS stimulation. Resident mPGES-1(-/-) peritoneal macrophages exhibited severely impaired PGE2-releasing activity but retained some LPS-inducible PGE2 production capacity. Both macrophage types showed a 50% decrease in PGE2 production with removal of one copy of the mPGES-1 gene. In vivo, mPGES-1 deletion abolished the LPS-stimulated production of PGE2 in spleen, kidney, and brain. Surprisingly, lack of mPGES-1 activity resulted in an 80-90% decrease in basal, cyclooxygenase-1 (COX-1)-dependent PGE2 production in stomach and spleen, and a 50% reduction in brain and kidney. Other prostaglandins (thromboxane B2, PGD2, PGF(2alpha), and 6-keto-PGF(1alpha)) were significantly elevated in stomachs of mPGES-1-null mice but not in other tissues. Examination of mRNA for several terminal prostaglandin synthases did not reveal changes in expression levels associated with mPGES-1 deficiency, indicating that gastric prostaglandin changes may be due to shunting of cyclooxygenase products to other terminal synthases. These data demonstrate for the first time a dual role for mPGES-1 in both inflammatory and COX-1-mediated PGE2 production and suggest an interdependence of prostanoid production with tissue-specific alterations of prostaglandin levels in the absence of mPGES-1.
authors.affiliation: Merck Frosst Centre for Therapeutic Research, Kirkland, Quebec H9H 3L1, Canada.
authors.forename: Louise
authors.initials: L
authors.lastname: Boulet
authors.forename: Marc
authors.initials: M
authors.lastname: Ouellet
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Bateman
authors.forename: Diane
authors.initials: D
authors.lastname: Ethier
authors.forename: M David
authors.initials: MD
authors.lastname: Percival
authors.forename: Denis
authors.initials: D
authors.lastname: Riendeau
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Mancini
authors.forename: Nathalie
authors.initials: N
authors.lastname: Méthot
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1; D015232:Dinoprostone / Q000096:biosynthesis*; D005753:Gastric Mucosa / Q000378:metabolism*; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins; D051379:Mice; D008861:Microsomes / Q000201:enzymology; D009928:Organ Specificity; D000071876:Prostaglandin-E Synthases; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011453:Prostaglandins / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D011453:Prostaglandins; D051545:Cyclooxygenase 1; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; C000605865:Ptges protein, mouse; D015232:Dinoprostone