title: Modulation of nitro-fatty acid signaling: prostaglandin reductase-1 is a nitroalkene reductase.
abstract: Inflammation, characterized by the activation of both resident and infiltrated immune cells, is accompanied by increased production of oxidizing and nitrating species. Nitrogen dioxide, the proximal nitrating species formed under these conditions, reacts with unsaturated fatty acids to yield nitroalkene derivatives. These electrophilic products modulate protein function via post-translational modification of susceptible nucleophilic amino acids. Nitroalkenes react with Keap1 to instigate Nrf2 signaling, activate heat shock response gene expression, and inhibit NF-κB-mediated signaling, inducing net anti-inflammatory and tissue-protective metabolic responses. We report the purification and characterization of a NADPH-dependent liver enzyme that reduces the nitroalkene moiety of nitro-oleic acid, yielding the inactive product nitro-stearic acid. Prostaglandin reductase-1 (PtGR-1) was identified as a nitroalkene reductase by protein purification and proteomic studies. Kinetic measurements, inhibition studies, immunological and molecular biology approaches as well as clinical analyses confirmed this identification. Overexpression of PtGR-1 in HEK293T cells promoted nitroalkene metabolism to inactive nitroalkanes, an effect that abrogated the Nrf2-dependent induction of heme oxygenase-1 expression by nitro-oleic acid. These results situate PtGR-1 as a critical modulator of both the steady state levels and signaling activities of fatty acid nitroalkenes in vivo.
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Dario A
authors.initials: DA
authors.lastname: Vitturi
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Chen-Shan
authors.initials: CS
authors.lastname: Chen
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Woodcock
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Sonia R
authors.initials: SR
authors.lastname: Salvatore
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Bonacci
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Koenitzer
authors.affiliation: Biomedical Mass Spectrometry Center. University of Pittsburgh, Pittsburgh, Pennsylvania 15261.
authors.forename: Nicolas A
authors.initials: NA
authors.lastname: Stewart
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Nobunao
authors.initials: N
authors.lastname: Wakabayashi
authors.affiliation: From the Department of Pharmacology and Chemical Biology.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kensler
authors.affiliation: From the Department of Pharmacology and Chemical Biology,. Electronic address: freerad@pitt.edu.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Freeman
authors.affiliation: From the Department of Pharmacology and Chemical Biology,. Electronic address: fjs2@pitt.edu.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Schopfer
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D008099:Liver / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D009574:Nitro Compounds / Q000378:metabolism*; D019301:Oleic Acid / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D013229:Stearic Acids / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; C486610:KEAP1 protein, rat; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D009574:Nitro Compounds; D013229:Stearic Acids; D019301:Oleic Acid; C031183:stearic acid; D000429:Alcohol Oxidoreductases; C082646:leukotriene B4 12-hydroxydehydrogenase; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1
keywords: Eicosanoid-specific Enzymes; Electrophile; Inflammation; Nitro-fatty Acid; Nitroalkene; Reactive Nitrogen Species; Redox Signaling; Thiol