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 γ 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 μM] or hydrogen peroxide (500 μM) (0.42±0.084 and 0.38±0.02 nmol·min−1·106 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·min−1·106 cells−1 for 2.4 μM HPETE and 500 μM H2O2 respectively). Finally, purified PGHS-2 consumed NO in the presence of HPETE or H2O2 (168 and 140 μM·min−1·μM enzyme−1 for HPETE and H2O2 respectively), in a haem-dependent manner, with 20 nM enzyme consuming up to 4 μM NO. Km (app) values for NO and 15(S)-HPETE were 1.7±0.2 and 0.45±0.16 μM 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.
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February 2005
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Research Article|
January 24 2005
Depletion of iNOS-derived nitric oxide by prostaglandin H synthase-2 in inflammation-activated J774.2 macrophages through lipohydroperoxidase turnover
Stephen R. CLARK;
Stephen R. CLARK
*Department of Medical Biochemistry and Immunology, School of Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, U.K.
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Peter B. ANNING;
Peter B. ANNING
*Department of Medical Biochemistry and Immunology, School of Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, U.K.
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Marcus J. COFFEY;
Marcus J. COFFEY
*Department of Medical Biochemistry and Immunology, School of Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, U.K.
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Andrew G. ROBERTS;
Andrew G. ROBERTS
*Department of Medical Biochemistry and Immunology, School of Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, U.K.
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Lawrence J. MARNETT;
Lawrence J. MARNETT
†Department of Biochemistry, Vanderbilt University, Nashville, TN 37232, U.S.A.
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Valerie B. O'DONNELL
Valerie B. O'DONNELL
1
*Department of Medical Biochemistry and Immunology, School of Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, U.K.
1To whom correspondence should be addressed (email o-donnellvb@cardiff.ac.uk).
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Biochem J (2005) 385 (3): 815–821.
Article history
Received:
August 09 2004
Revision Received:
September 16 2004
Accepted:
October 04 2004
Accepted Manuscript online:
October 04 2004
Citation
Stephen R. CLARK, Peter B. ANNING, Marcus J. COFFEY, Andrew G. ROBERTS, Lawrence J. MARNETT, Valerie B. O'DONNELL; Depletion of iNOS-derived nitric oxide by prostaglandin H synthase-2 in inflammation-activated J774.2 macrophages through lipohydroperoxidase turnover. Biochem J 1 February 2005; 385 (3): 815–821. doi: https://doi.org/10.1042/BJ20041353
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