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Brat C, Huynh Phuoc HP, Awad O, Parmar BS, Hellmuth N, Heinicke U, Amr S, Grimmer J, Sürün D, Husnjak K, Carlsson M, Fahrer J, Bauer T, Krieg SC, Manolikakes G, Zacharowski K, Steinhilber D, Münch C, Maier TJ, Roos J. Endogenous anti-tumorigenic nitro-fatty acids inhibit the ubiquitin-proteasome system by directly targeting the 26S proteasome. Cell Chem Biol 2023; 30:1277-1294.e12. [PMID: 37473760 DOI: 10.1016/j.chembiol.2023.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/11/2023] [Accepted: 06/16/2023] [Indexed: 07/22/2023]
Abstract
Nitro-fatty acids (NFAs) are endogenous lipid mediators causing a spectrum of anti-inflammatory effects by covalent modification of key proteins within inflammatory signaling pathways. Recent animal models of solid tumors have helped demonstrate their potential as anti-tumorigenic therapeutics. This study evaluated the anti-tumorigenic effects of NFAs in colon carcinoma cells and other solid and leukemic tumor cell lines. NFAs inhibited the ubiquitin-proteasome system (UPS) by directly targeting the 26S proteasome, leading to polyubiquitination and inhibition of the proteasome activities. UPS suppression induced the unfolded protein response, resulting in tumor cell death. The NFA-mediated effects were substantial, specific, and enduring, representing a unique mode of action for UPS suppression. This study provides mechanistic insights into the biological actions of NFAs as possible endogenous tumor-suppressive factors, indicating that NFAs might be key structures for designing a novel class of direct proteasome inhibitors.
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Affiliation(s)
- Camilla Brat
- Department of Anesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe-University, Frankfurt/Main 60590 Hesse, Germany
| | - Hai Phong Huynh Phuoc
- Department Safety of Medicinal Products and Medical Devices, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Langen, 63225 Hesse, Germany
| | - Omar Awad
- Department Safety of Medicinal Products and Medical Devices, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Langen, 63225 Hesse, Germany
| | - Bhavesh S Parmar
- Institute of Biochemistry II, University Hospital Frankfurt, Goethe-University, Frankfurt/Main, 60590 Hesse, Germany
| | - Nadine Hellmuth
- Department of Anesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe-University, Frankfurt/Main 60590 Hesse, Germany
| | - Ulrike Heinicke
- Department of Anesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe-University, Frankfurt/Main 60590 Hesse, Germany
| | - Shady Amr
- Institute of Biochemistry II, University Hospital Frankfurt, Goethe-University, Frankfurt/Main, 60590 Hesse, Germany
| | - Jennifer Grimmer
- Department of Chemistry, RPTU Kaiserslautern-Landau, Kaiserslautern, 67663 Rhineland-Palatinate, Germany
| | - Duran Sürün
- Medical Systems Biology, Faculty of Medicine, TU Dresden, Dresden, 01307 Saxony, Germany
| | - Koraljka Husnjak
- Institute of Biochemistry II, University Hospital Frankfurt, Goethe-University, Frankfurt/Main, 60590 Hesse, Germany
| | - Max Carlsson
- Division of Food Chemistry and Toxicology, Department of Chemistry, RPTU Kaiserslautern-Landau, Kaiserslautern, 67663 Rhineland-Palatinate, Germany
| | - Jörg Fahrer
- Division of Food Chemistry and Toxicology, Department of Chemistry, RPTU Kaiserslautern-Landau, Kaiserslautern, 67663 Rhineland-Palatinate, Germany
| | - Tom Bauer
- Department Safety of Medicinal Products and Medical Devices, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Langen, 63225 Hesse, Germany
| | - Sara-Cathrin Krieg
- Department of Chemistry, RPTU Kaiserslautern-Landau, Kaiserslautern, 67663 Rhineland-Palatinate, Germany
| | - Georg Manolikakes
- Department of Chemistry, RPTU Kaiserslautern-Landau, Kaiserslautern, 67663 Rhineland-Palatinate, Germany
| | - Kai Zacharowski
- Department of Anesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe-University, Frankfurt/Main 60590 Hesse, Germany
| | - Dieter Steinhilber
- Institute of Pharmaceutical Chemistry, Goethe-University, Frankfurt/Main, 60438 Hesse, Germany
| | - Christian Münch
- Institute of Biochemistry II, University Hospital Frankfurt, Goethe-University, Frankfurt/Main, 60590 Hesse, Germany
| | - Thorsten Jürgen Maier
- Department of Anesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe-University, Frankfurt/Main 60590 Hesse, Germany; Department Safety of Medicinal Products and Medical Devices, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Langen, 63225 Hesse, Germany
| | - Jessica Roos
- Department of Anesthesia, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe-University, Frankfurt/Main 60590 Hesse, Germany; Department Safety of Medicinal Products and Medical Devices, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Langen, 63225 Hesse, Germany.
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Schopfer FJ, Khoo NKH. Nitro-Fatty Acid Logistics: Formation, Biodistribution, Signaling, and Pharmacology. Trends Endocrinol Metab 2019; 30:505-519. [PMID: 31196614 PMCID: PMC7121905 DOI: 10.1016/j.tem.2019.04.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/25/2019] [Accepted: 04/25/2019] [Indexed: 02/04/2023]
Abstract
In addition to supporting cellular energetic demands and providing building blocks for lipid synthesis, fatty acids (FAs) are precursors of potent signaling molecules. In particular, the presence of conjugated double bonds on the fatty-acyl chain provides a preferential target for nitration generating nitro-FAs (NO2-FAs). The formation of NO2-FAs is a nonenzymatic process that requires reactive nitrogen species and occurs locally at the site of inflammation or during gastric acidification. NO2-FAs are electrophilic and display pleiotropic signaling actions through reversible protein alkylation. This review focuses on the endogenously formed NO2-FAs' mechanism of absorption, systemic distribution, signaling, and preclinical models. Understanding the dynamics of these processes will facilitate targeted dietary interventions and further the current pharmacological development aimed at low-grade inflammatory diseases.
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Affiliation(s)
- Francisco J Schopfer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
| | - Nicholas K H Khoo
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
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3
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Buchan GJ, Bonacci G, Fazzari M, Salvatore SR, Gelhaus Wendell S. Nitro-fatty acid formation and metabolism. Nitric Oxide 2018; 79:38-44. [PMID: 30006146 DOI: 10.1016/j.niox.2018.07.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/29/2018] [Accepted: 07/03/2018] [Indexed: 12/16/2022]
Abstract
Nitro-fatty acids (NO2-FA) are pleiotropic modulators of redox signaling pathways. Their effects on inflammatory signaling have been studied in great detail in cell, animal and clinical models primarily using exogenously administered nitro-oleic acid. While we know a considerable amount regarding NO2-FA signaling, endogenous formation and metabolism is relatively unexplored. This review will cover what is currently known regarding the proposed mechanisms of NO2-FA formation, dietary modulation of endogenous NO2-FA levels, pathways of NO2-FA metabolism and the detection of NO2-FA and corresponding metabolites.
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Affiliation(s)
- Gregory J Buchan
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Gustavo Bonacci
- CIBICI - CONICET, Departamento de Bioquímica Clínica Facultad de Ciencias Químicas, (U.N.C.), Haya de la Torre y Medina Allende Ciudad Universitaria, Córdoba C.P. N°: X5000HUA, Argentina
| | - Marco Fazzari
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA; Fondazione Ri.MED, Via Bandiera 11, 90133 Palermo, Italy
| | - Sonia R Salvatore
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Stacy Gelhaus Wendell
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA; Clinical Translational Science Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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4
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Turell L, Steglich M, Alvarez B. The chemical foundations of nitroalkene fatty acid signaling through addition reactions with thiols. Nitric Oxide 2018; 78:S1089-8603(17)30305-1. [PMID: 29578058 DOI: 10.1016/j.niox.2018.03.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 11/30/2022]
Abstract
Nitroalkene fatty acids can be formed in vivo and administered exogenously. They exert pleiotropic signaling actions with cytoprotective and antiinflammatory effects. The presence of the potent electron withdrawing nitro group confers electrophilicity to the adjacent β-carbon. Thiols (precisely, thiolates) are strong nucleophiles and can react with nitroalkene fatty acids through reversible Michael addition reactions. In addition, nitroalkene fatty acids can undergo several other processes including metabolic oxidation, reduction, esterification, nitric oxide release and partition into hydrophobic compartments. The signaling actions of nitroalkenes are mainly mediated by reactions with critical thiols in regulatory proteins. Thus, the thio-Michael addition reaction provides a framework for understanding the molecular basis of the biological effects of nitroalkene fatty acids at the crossroads of thiol signaling and electrophilic lipid signaling. In this review, we describe the reactions of nitroalkene fatty acids in biological contexts. We focus on the Michael addition-elimination reaction with thiols and its mechanism, and extrapolate kinetic and thermodynamic considerations to in vivo settings.
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Affiliation(s)
- Lucía Turell
- Laboratorio de Enzimología, Facultad de Ciencias and Center for Free Radical and Biomedical Research, Universidad de la República, Montevideo, Uruguay.
| | - Martina Steglich
- Laboratorio de Enzimología, Facultad de Ciencias and Center for Free Radical and Biomedical Research, Universidad de la República, Montevideo, Uruguay
| | - Beatriz Alvarez
- Laboratorio de Enzimología, Facultad de Ciencias and Center for Free Radical and Biomedical Research, Universidad de la República, Montevideo, Uruguay
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Electrophilic fatty acid nitroalkenes regulate Nrf2 and NF-κB signaling:A medicinal chemistry investigation of structure-function relationships. Sci Rep 2018; 8:2295. [PMID: 29396403 PMCID: PMC5797128 DOI: 10.1038/s41598-018-20460-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 01/18/2018] [Indexed: 02/07/2023] Open
Abstract
Fatty acid nitroalkene derivatives (NO2-FA) activate Nrf2-regulated antioxidant gene expression and inhibit NF-κB-dependent cytokine expression. To better define NO2-FA structure-function relationships, a series of 22 new chemical entities (NCEs) containing an electrophilic nitroalkene functional group were synthesized and screened for both Nrf2- and NF-κB activities using luciferase-based assays. The structural variables were acyl chain length (11 to 24 carbons) and position of the electrophilic nitroalkene group. In luciferase-based reporter assays, Nrf2 was maximally activated by omega-12 nitroalkene fatty acids while TNFα stimulated NF-κB-inhibition was maximal for omega-5 nitroalkenes. The top pathway-modulating NO2-FAs were a) evaluated for an ability to activate Nrf2-dependent signaling and inhibit NF-κB-dependent inflammatory responses of RAW264.7 cells and b) compared to electrophilic compounds in clinical development. These findings revealed that 8/9-nitro-eicos-8-enoic acid (NCE-10) was collectively the most effective NCE and that both the α and ω acyl chain lengths influence nitroalkene activation of Nrf2 and inhibition of NF-κB signaling. This insight will guide development of more effective non-natural homologs of endogenously-detectable fatty acid nitroalkenes as anti-inflammatory and anti-fibrotic drug candidates.
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6
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Evaluation of 10-Nitro Oleic Acid Bio-Elimination in Rats and Humans. Sci Rep 2017; 7:39900. [PMID: 28054588 PMCID: PMC5215368 DOI: 10.1038/srep39900] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/29/2016] [Indexed: 12/12/2022] Open
Abstract
Nitrated fatty acids are endogenously present in human and animal tissues, as well as in plant-derived oils. In particular, 10-nitro oleic acid (10-NO2-OA) potently induces Nrf2-dependent antioxidant gene expression and inhibits TLR4/NF-κB signaling, thus promoting an overall cyto-protective and anti-inflammatory response. 10-NO2-OA has been extensively tested in animal models and is currently undergoing clinical evaluation in humans. Bio-elimination pathways for 10-NO2-OA were evaluated in rats (30 mg/kg·day) and in humans (0.34 mg/kg) using samples obtained from a double-blind, dose-rising clinical trial. Quantitative radiochromatographic/MS analysis indicated that the renal and fecal pathways are the main routes for 10-NO2-OA excretion in rats, and allowed the identification of 4-nitro-octanedioic acid (NO2-8:0-diCOOH) as the most abundant metabolite in rat urine. In addition, high resolution LC-MS/MS analysis revealed the presence of a novel series of urinary metabolites including ω-carboxylation and β-oxidation products, as well as N-acetylcysteine, taurine and sulfo-conjugates in both rats and humans. Overall, the findings reported herein not only provide valuable tools for the experimental evaluation of 10-NO2-OA levels in vivo, but importantly they also set the basis for monitoring its metabolism during potential clinical interventions in humans.
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7
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Electrophilic Nitro-Fatty Acids: Nitric Oxide and Nitrite-Derived Metabolic and Inflammatory Signaling Mediators. Nitric Oxide 2017. [DOI: 10.1016/b978-0-12-804273-1.00016-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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8
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Fazzari M, Khoo NKH, Woodcock SR, Jorkasky DK, Li L, Schopfer FJ, Freeman BA. Nitro-fatty acid pharmacokinetics in the adipose tissue compartment. J Lipid Res 2016; 58:375-385. [PMID: 27913584 DOI: 10.1194/jlr.m072058] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/07/2016] [Indexed: 01/14/2023] Open
Abstract
Electrophilic nitro-FAs (NO2-FAs) promote adaptive and anti-inflammatory cell signaling responses as a result of an electrophilic character that supports posttranslational protein modifications. A unique pharmacokinetic profile is expected for NO2-FAs because of an ability to undergo reversible reactions including Michael addition with cysteine-containing proteins and esterification into complex lipids. Herein, we report via quantitative whole-body autoradiography analysis of rats gavaged with radiolabeled 10-nitro-[14C]oleic acid, preferential accumulation in adipose tissue over 2 weeks. To better define the metabolism and incorporation of NO2-FAs and their metabolites in adipose tissue lipids, adipocyte cultures were supplemented with 10-nitro-oleic acid (10-NO2-OA), nitro-stearic acid, nitro-conjugated linoleic acid, and nitro-linolenic acid. Then, quantitative HPLC-MS/MS analysis was performed on adipocyte neutral and polar lipid fractions, both before and after acid hydrolysis of esterified FAs. NO2-FAs preferentially incorporated in monoacyl- and diacylglycerides, while reduced metabolites were highly enriched in triacylglycerides. This differential distribution profile was confirmed in vivo in the adipose tissue of NO2-OA-treated mice. This pattern of NO2-FA deposition lends new insight into the unique pharmacokinetics and pharmacologic actions that could be expected for this chemically-reactive class of endogenous signaling mediators and synthetic drug candidates.
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Affiliation(s)
- Marco Fazzari
- Fondazione Ri.MED, 90133 Palermo, Italy.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Nicholas K H Khoo
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Steven R Woodcock
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | | | - Lihua Li
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Francisco J Schopfer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Bruce A Freeman
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
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Hlekhlai S, Samakkanad N, Sawangphon T, Pohmakotr M, Reutrakul V, Soorukram D, Jaipetch T, Kuhakarn C. Oxone®/KI-Mediated Nitration of Alkenes and Alkynes: Synthesis of Nitro- and β-Iodonitro-Substituted Alkenes. European J Org Chem 2014. [DOI: 10.1002/ejoc.201402750] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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10
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Plancarte A, Romero JR, Nava G, Reyes H, Hernández M. Evaluation of the non-catalytic binding function of Ts26GST a glutathione transferase isoform of Taenia solium. Exp Parasitol 2014; 138:63-70. [PMID: 24560769 DOI: 10.1016/j.exppara.2014.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 02/07/2014] [Accepted: 02/09/2014] [Indexed: 10/25/2022]
Abstract
Taenia solium glutathione transferase isoform of 26.5 kDa (Ts26GST) was observed to bind non-catalytically to porphyrins, trans-trans-dienals, bile acids and fatty acids, as assessed by inhibition kinetics, fluorescence spectroscopy and competitive fluorescence assays with 8-anilino-1-naphthalene sulfonate (ANS). The quenching of Ts26GST intrinsic fluorescence allowed for the determination of the dissociation constants (KD) for all ligands. Obtained data indicate that Ts26GST binds to all ligands but with different affinity. Porphyrins and lipid peroxide products inhibited Ts26GST catalytic activity up to 100% in contrast with only 20-30% inhibition observed for bile acids and two saturated fatty acids. Non-competitive type inhibition was observed for all enzyme inhibitor ligands except for trans-trans-2,4-decadienal, which exhibited uncompetitive type inhibition. The dissociation constant value KD = 0.7 μM for the hematin ligand, determined by competitive fluorescence assays with ANS, was in good agreement with its inhibition kinetic value Ki = 0.3 μM and its intrinsic fluorescence quenching KD = 0.7 μM. The remaining ligands did not displace ANS from the enzyme suggesting the existence of different binding sites. In addition to the catalytic activity of Ts26GST the results obtained suggest that the enzyme exhibits a ligandin function with broad specificity towards nonsubstrate ligands.
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Affiliation(s)
- A Plancarte
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico.
| | - J R Romero
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico
| | - G Nava
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico
| | - H Reyes
- Laboratorio de Bioquímica-Genética y División de Investigación, Instituto Nacional de Pediatría, D.F., Mexico
| | - M Hernández
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico
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Salvatore SR, Vitturi DA, Baker PRS, Bonacci G, Koenitzer JR, Woodcock SR, Freeman BA, Schopfer FJ. Characterization and quantification of endogenous fatty acid nitroalkene metabolites in human urine. J Lipid Res 2013; 54:1998-2009. [PMID: 23620137 DOI: 10.1194/jlr.m037804] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The oxidation and nitration of unsaturated fatty acids transforms cell membrane and lipoprotein constituents into mediators that regulate signal transduction. The formation of 9-NO2-octadeca-9,11-dienoic acid and 12-NO2-octadeca-9,11-dienoic acid stems from peroxynitrite- and myeloperoxidase-derived nitrogen dioxide reactions as well as secondary to nitrite disproportionation under the acidic conditions of digestion. Broad anti-inflammatory and tissue-protective responses are mediated by nitro-fatty acids. It is now shown that electrophilic fatty acid nitroalkenes are present in the urine of healthy human volunteers (9.9 ± 4.0 pmol/mg creatinine); along with electrophilic 16- and 14-carbon nitroalkenyl β-oxidation metabolites. High resolution mass determinations and coelution with isotopically-labeled metabolites support renal excretion of cysteine-nitroalkene conjugates. These products of Michael addition are in equilibrium with the free nitroalkene pool in urine and are displaced by thiol reaction with mercury chloride. This reaction increases the level of free nitroalkene fraction >10-fold and displays a K(D) of 7.5 × 10(-6) M. In aggregate, the data indicates that formation of Michael adducts by electrophilic fatty acids is favored under biological conditions and that reversal of these addition reactions is critical for detecting both parent nitroalkenes and their metabolites. The measurement of this class of mediators can constitute a sensitive noninvasive index of metabolic and inflammatory status.
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Affiliation(s)
- Sonia R Salvatore
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Lewerenz J, Dargusch R, Maher P. Lactacidosis modulates glutathione metabolism and oxidative glutamate toxicity. J Neurochem 2010; 113:502-14. [PMID: 20132475 DOI: 10.1111/j.1471-4159.2010.06621.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Lactate and acidosis increase infarct size in humans and in animal models of cerebral ischemia but the mechanisms by which they exert their neurotoxic effects are poorly understood. Oxidative glutamate toxicity is a form of nerve cell death, wherein glutamate inhibits cystine uptake via the cystine/glutamate antiporter system leading to glutathione depletion, accumulation of reactive oxygen species and, ultimately, programmed cell death. Using the hippocampal cell line, HT22, we show that lactate and acidosis exacerbate oxidative glutamate toxicity and further decrease glutathione levels. Acidosis but not lactate inhibits system , whereas both acidosis and lactate inhibit the enzymatic steps of glutathione synthesis downstream of cystine uptake. In contrast, when glutathione synthesis is completely inhibited by cystine-free medium, acidosis partially protects against glutathione depletion and cell death. Both effects of acidosis are also present in primary neuronal and astrocyte cultures. Furthermore, we show that some neuroprotective compounds are much less effective in the presence of lactacidosis. Our findings indicate that lactacidosis modulates glutathione metabolism and neuronal cell death. Furthermore, lactacidosis may interfere with the action of some neuroprotective drugs rendering these less likely to be therapeutically effective in cerebral ischemia.
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Affiliation(s)
- Jan Lewerenz
- Department for Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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