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Depletion of iNOS-derived nitric oxide by prostaglandin H synthase-2 in inflammation-activated J774.2 macrophages through lipohydroperoxidase turnover

Clark, Stephen Robert, Anning, Peter Brian, Coffey, Marcus Jonathan, Roberts, Andrew Glyn, Marnett, Lawrence J. and O'Donnell, Valerie Bridget 2005. Depletion of iNOS-derived nitric oxide by prostaglandin H synthase-2 in inflammation-activated J774.2 macrophages through lipohydroperoxidase turnover. Biochemical Journal 385 (3) , pp. 815-821. 10.1042/BJ20041353

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Abstract

PGHS-2 (prostaglandin H synthase-2) is induced in mammalian cells by pro-inflammatory cytokines in tandem with iNOS [high-output ('inducible') nitric oxide synthase], and is co-localized with iNOS and nitrotyrosine in human atheroma macrophages. Herein, murine J774.2 macrophages incubated with lipopolysaccharide and interferon gamma showed induction of PGHS-2 and generated NO using iNOS that could be completely depleted by 12(S)-HPETE [12(S)-hydroperoxyeicosatetraenoic acid; 2.4 muM] or hydrogen peroxide (500 microM) (0.42+/-0.084 and 0.38+/-0.02 nmol x min(-1) x 10(6) cells(-1) for HPETE and H2O2 respectively). COS-7 cells transiently transfected with human PGHS-2 also showed HPETE- or H2O2-dependent NO decay (0.44+/-0.016 and 0.20+/-0.04 nmol x min(-1) x 10(6) cells(-1) for 2.4 microM HPETE and 500 microM H2O2 respectively). Finally, purified PGHS-2 consumed NO in the presence of HPETE or H2O2 (168 and 140 microM x min(-1) x microM enzyme(-1) for HPETE and H2O2 respectively), in a haem-dependent manner, with 20 nM enzyme consuming up to 4 microM NO. K(m) (app) values for NO and 15(S)-HPETE were 1.7+/-0.2 and 0.45+/-0.16 microM respectively. These data indicate that PGHS-2 catalytically consumes NO during peroxidase turnover and that pro-inflammatory cytokines simultaneously upregulate NO synthesis and degradation pathways in murine macrophages. Catalytic NO consumption by PGHS-2 represents a novel interaction between NO and PGHS-2 that may impact on the biological effects of NO in vascular signalling and inflammation.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Systems Immunity Research Institute (SIURI)
Uncontrolled Keywords: cyclo-oxygenase ; inflammation ; nitric oxide ; peroxidase ; prostaglandin H synthase-2 (PGHS-2) ; reactive nitrogen species
Publisher: Portland Press
ISSN: 0264-6021
Last Modified: 04 Jun 2017 01:31
URI: http://orca.cf.ac.uk/id/eprint/208

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