title: Interactions of 2-O-arachidonylglycerol ether and ibuprofen with the allosteric and catalytic subunits of human COX-2.
abstract: Prostaglandin (PG) endoperoxide H synthase (PGHS)-2, also known as cyclooxygenase (COX)-2, can convert arachidonic acid (AA) to PGH2 in the committed step of PG synthesis. PGHS-2 functions as a conformational heterodimer composed of an allosteric (Eallo) and a catalytic (Ecat) monomer. Here we investigated the interplay between human (hu)PGHS-2 and an alternative COX substrate, the endocannabinoid, 2-arachidonoylglycerol (2-AG), as well as a stable analog, 2-O-arachidonylglycerol ether (2-AG ether). We also compared the inhibition of huPGHS-2-mediated oxygenation of AA, 2-AG, and 2-AG ether by the well-known COX inhibitor, ibuprofen. When tested with huPGHS-2, 2-AG and 2-AG ether exhibit very similar kinetic parameters, responses to stimulation by FAs that are not COX substrates, and modes of inhibition by ibuprofen. The 2-AG ether binds Ecat more tightly than Eallo and, thus, can be used as a stable Ecat-specific substrate to examine certain Eallo-dependent responses. Ibuprofen binding to Eallo of huPGHS-2 completely blocks 2-AG or 2-AG ether oxygenation; however, inhibition by ibuprofen of huPGHS-2-mediated oxygenation of AA engages a combination of both allosteric and competitive mechanisms.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Liang
authors.initials: L
authors.lastname: Dong
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Hechang
authors.initials: H
authors.lastname: Zou
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Chong
authors.initials: C
authors.lastname: Yuan
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Yu H
authors.initials: YH
authors.lastname: Hong
authors.affiliation: Department of Pharmacology, University of Colorado-Denver, Aurora, CO 80045.
authors.forename: Charis L
authors.initials: CL
authors.lastname: Uhlson
authors.affiliation: Department of Pharmacology, University of Colorado-Denver, Aurora, CO 80045 smithww@umich.edu robert.murphy@ucdenver.edu.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Murphy
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109 smithww@umich.edu robert.murphy@ucdenver.edu.
authors.forename: William L
authors.initials: WL
authors.lastname: Smith
mesh_terms: D000495:Allosteric Site / Q000187:drug effects / Q000235:genetics; D016718:Arachidonic Acid / Q000378:metabolism; D001095:Arachidonic Acids / Q000378:metabolism* / Q000494:pharmacology; D020134:Catalytic Domain / Q000187:drug effects / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000737:chemistry / Q000187:drug effects / Q000235:genetics*; D063388:Endocannabinoids / Q000378:metabolism* / Q000494:pharmacology; D004986:Ether / Q000378:metabolism / Q000494:pharmacology; D005989:Glycerides / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007052:Ibuprofen / Q000008:administration & dosage; D044262:Prostaglandin H2 / Q000096:biosynthesis
chemical_list: D001095:Arachidonic Acids; D063388:Endocannabinoids; D005989:Glycerides; D004986:Ether; D016718:Arachidonic Acid; D044262:Prostaglandin H2; C094503:glyceryl 2-arachidonate; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D007052:Ibuprofen
keywords: 2-arachindonoylglycerol; arachidonic acid; cyclooxygenase-2; ibuprofen; palmitic acid; prostaglandin, half-sites