title: Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E2and D2by activated human leukocytes.
abstract: The 2 hemiketal (HK) eicosanoids HKD2and HKE2are the major products of the biosynthetic crossover of the 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) pathways. HKs result from the rearrangement of a di-endoperoxide intermediate formed in the COX-2-dependent oxygenation of 5S-hydroxyeicosatetraenoic acid (5S-HETE). We analyzed HK biosynthesis in human leukocytes stimulatedex vivoand defined the biosynthetic roles of 5-LOX and COX-2, using inhibitors and incubations with exogenous substrates. Activation of leukocytes with LPS followed by treatment with the calcium ionophore A23187 resulted in the formation of PGE2, 5-HETE, and LTB4as the principal metabolites of COX-2 and 5-LOX, respectively. The formation of HKD2and HKE2was highest after 15 min LPS treatment, and at that time, levels were similar to PGE2, but less than 5-HETE and LTB4The time course of HK formation paralleled that of 5-HETE and LTB4, implying the availability of the 5S-HETE substrate as a limiting factor in biosynthesis rather than expression levels of COX-2. Specific inhibitors of COX-2 and 5-LOX decreased formation of HKD2and HKE2Platelets did not form HKs from exogenous 5S-HETE, implying that COX-1 is not involved. HKs are early products during an inflammatory event and require cells that express 5-LOX and COX-2 for their biosynthesis.-Giménez-Bastida, J. A., Shibata, T., Uchida, K., Schneider, C. Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E2and D2by activated human leukocytes.
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical School, Nashville, Tennessee, USA.|Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical School, Nashville, Tennessee, USA.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Giménez-Bastida
authors.affiliation: Division of Biofunctional Chemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan; and.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shibata
authors.affiliation: Division of Biofunctional Chemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan; and.|Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical School, Nashville, Tennessee, USA; claus.schneider@vanderbilt.edu.|Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical School, Nashville, Tennessee, USA.
authors.forename: Claus
authors.initials: C
authors.lastname: Schneider
mesh_terms: D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism; D001792:Blood Platelets / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis*; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000096:biosynthesis*
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D016718:Arachidonic Acid; D000001:Calcimycin; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D001094:Arachidonate 5-Lipoxygenase; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C583212:ALOX5 protein, human; D015232:Dinoprostone; D015230:Prostaglandin D2
keywords: arachidonic acid; leukotriene; prostaglandin