L J Marnett

Vanderbilt University, Nashville, Michigan, United States

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Publications (480)2293.8 Total impact

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    ABSTRACT: The structurally related exocyclic guanine adducts α-hydroxypropano-dG (α-OH-PdG), γ-hydroxypropano-dG (γ-OH-PdG), and M1dG are formed when DNA is exposed to the reactive aldehydes acrolein and malondialdehyde (MDA). These lesions are believed to form the basis for the observed cytotoxicity and mutagenicity of acrolein and MDA. In an effort to understand the enzymatic pathways and chemical mechanisms that are involved in the repair of acrolein- and MDA-induced DNA damage, we investigated the ability of the DNA repair enzyme AlkB, an α-ketoglutarate/Fe(II) dependent dioxygenase, to process α-OH-PdG, γ-OH-PdG, and M1dG in both single- and double-stranded DNA contexts. By monitoring the repair reactions using quadrupole time-of-flight (Q-TOF) mass spectrometry, it was established that AlkB can oxidatively dealkylate γ-OH-PdG most efficiently, followed by M1dG and α-OH-PdG. The AlkB repair mechanism involved multiple intermediates and complex, overlapping repair pathways. For example, the three exocyclic guanine adducts were shown to be in equilibrium with open-ring aldehydic forms, which were trapped using (pentafluorobenzyl)hydroxylamine (PFBHA) or NaBH4. AlkB repaired the trapped open-ring form of γ-OH-PdG but not the trapped open-ring of α-OH-PdG. Taken together, this study provides a detailed mechanism by which three-carbon bridge exocyclic guanine adducts can be processed by AlkB and suggests an important role for the AlkB family of dioxygenases in protecting against the deleterious biological consequences of acrolein and MDA.
    Chemical Research in Toxicology 08/2014; · 3.67 Impact Factor
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    ABSTRACT: Lipid electrophiles modify cellular targets, altering their function. Here, we describe histones as major targets for modification by 4-oxo-2-nonenal, resulting in a stable Lys modification structurally analogous to other histone Lys acylations. Seven adducts were identified in chromatin isolated from intact cells - four 4-ketoamides to Lys and 3 Michael adducts to His. A 4-ketoamide adduct residing at H3K27 was identified in stimulated macrophages. Modification of histones H3 and H4 prevented nucleosome assembly.
    Journal of the American Chemical Society 08/2014; · 10.68 Impact Factor
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    ABSTRACT: Culture extracts from the cave-derived actinomycete Nonomuraea specus were investigated, resulting in the discovery of a new S-bridged pyronaphthoquinone dimer and its monomeric progenitors designated hypogeamicins A-D (1-4). The structures were elucidated using NMR spectroscopy, and the relative stereochemistries of the pyrans were inferred using NOE and comparison to previously reported compounds. Absolute stereochemistry was determined using quantum chemical calculations of specific rotation and vibrational and electronic circular dichroism spectra, after an extensive conformational search and including solute-solvent polarization effects, and comparing with the corresponding experimental data for the monomeric congeners. Interestingly, the dimeric hypogeamicin A (1) was found to be cytotoxic to the colon cancer derived cell line TCT-1 at low micromolar ranges, but not bacteria, whereas the monomeric precursors possessed antibiotic activity but no significant TCT-1 cytotoxicity.
    Journal of natural products. 07/2014;
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    ABSTRACT: Lipid and lipid metabolite profiling are important parameters in understanding the pathogenesis of many diseases. Alkynylated polyunsaturated fatty acids are potentially useful probes for tracking the fate of fatty acid metabolites. The non-enzymatic and enzymatic oxidation of ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid were compared to that of linoleic and arachidonic acid. There was no detectable difference in the primary products of non-enzymatic oxidation, which comprised cis,trans-hydroxy fatty acids. Similar hydroxy fatty acid products were formed when ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid were reacted with lipoxygenase enzymes that introduce oxygen at different positions in the carbon chains. The rates of oxidation of ω-alkynylated fatty acids were reduced compared to the natural fatty acids. Cyclooxygenase-1 and -2 did not oxidize alkynyl linoleic, but efficiently oxidized alkynyl arachidonic acid. The products were identified as alkynyl 11-hydroxy-eicosatetraenoic acid, alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid, and alkynyl prostaglandins. This deviation from the metabolic profile of arachidonic acid may limit the utility of alkynyl arachidonic acid in the tracking of cyclooxygenase based lipid oxidation. The formation of alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid compared to alkynyl prostaglandins suggests that the ω-alkyne group causes a conformational change in the fatty acid bound to the enzyme, which reduces the efficiency of cyclization of dioxalanyl intermediates to endoperoxide intermediates. Overall, ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid appear to be metabolically competent surrogates for tracking the fate of polyunsaturated fatty acids when looking at models involving autoxidation and oxidation by lipoxygenases.
    Journal of the American Chemical Society 07/2014; · 10.68 Impact Factor
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    ABSTRACT: The metabolic fate of a compound is determined by numerous factors including its chemical structure. Although the metabolic options for a variety of functional groups are well understood, and can often provide a rationale for comparison of toxicity based on structural analogy, at times, quite minor structural variations may have major consequences for metabolic outcomes and toxicity. In this paper, the effects of structural variations on metabolic outcomes is detailed for a group of related hydroxy- and alkoxy- substituted allyl- and propenylbenzenes. These classes of compounds are naturally occurring constituents of a variety of botanical based food items. The classes vary from one another by the presence or absence of alkylation of their para-hydroxyl substituents and/or the position of the double bond in the alkyl side chain. We provide an overview of how these subtle structural variations alter the metabolism of these important food-borne compounds, ultimately influencing their toxicity, particularly their DNA reactivity and carcinogenic potential. The data reveal that detailed knowledge of the consequences of subtle structural variations for metabolism is essential for adequate comparison of structurally related chemicals. Taken together, it is concluded that predictions in toxicological risk assessment should not be performed on the basis of structural analogy only, but should include analogy of metabolic pathways across compounds and species.
    Chemical research in toxicology. 05/2014;
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    ABSTRACT: Pharmacologic augmentation of endogenous cannabinoid (eCB) signaling is an emerging therapeutic approach for the treatment of a broad range of pathophysiological conditions. Thus far, pharmacological approaches have focused on inhibition of the canonical eCB inactivation pathways - fatty acid amide hydrolase (FAAH) for anandamide and monoacylglycerol lipase (MAGL) for 2-arachidonoylglycerol. We review here the experimental evidence that cyclooxygenase-2 (COX-2)-mediated eCB oxygenation represents a third mechanism for terminating eCB action at cannabinoid receptors. We describe the development, molecular mechanisms, and in vivo validation of 'substrate-selective' COX-2 inhibitors (SSCIs) that prevent eCB inactivation by COX-2 without affecting prostaglandin (PG) generation from arachidonic acid (AA). Lastly, we review recent data on the potential therapeutic applications of SSCIs with a focus on neuropsychiatric disorders.
    Trends in Pharmacological Sciences 05/2014; · 9.25 Impact Factor
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    ABSTRACT: Cyclooxygenase-2 (COX-2) is an enzyme involved in tumorigenesis, and inhibitors of the enzyme are increasingly used as adjuvant modulators in anticancer therapies due to their synergistic effects with traditional chemotherapeutics. COX-2 is also reported to cause resistance towards antitumor agents, such as cisplatin. Here, the first covalently linked conjugates of cisplatin and COX inhibitors are reported. These conjugates exhibit concerted transport of both drugs into tumor cells and simultaneous action upon intracellular cleavage. These platinum(IV) complexes show highly increased cytotoxicity compared with cisplatin and are even able to overcome cisplatin-related resistance of tumor cells. While the results reported show that COX-2 inhibition is not directly responsible for the potent activities of these conjugates, they do represent useful tool compounds for the elucidation of the influence of COX inhibitors on the efficacy of antitumor agents.
    ChemMedChem 05/2014; · 2.84 Impact Factor
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    ABSTRACT: Cyclooxygenase-1 (COX-1), but not COX-2, is expressed at high levels in the early stages of human epithelial ovarian cancer where it seems to play a key role in cancer onset and progression. As a consequence, COX-1 is an ideal biomarker for early ovarian cancer detection. A series of novel fluorinated COX-1-targeted imaging agents derived from P6 was developed by using a highly selective COX-1 inhibitor as a lead compound. Among these new compounds, designed by structural modification of P6, 3-(5-chlorofuran-2-yl)-5-(fluoromethyl)-4-phenylisoxazole ([(18/19)F]-P6) is the most promising derivative [IC50 = 2.0 μM (purified oCOX-1) and 1.37 μM (hOVCAR-3 cell COX-1)]. Its tosylate precursor was also prepared and, a method for radio[(18)F]chemistry was developed and optimized. The radiochemistry was carried out using a carrier-free K(18)F/Kryptofix 2.2.2 complex, that afforded [(18)F]-P6 in good radiochemical yield (18%) and high purity (>95%). In vivo PET/CT imaging data showed that the radiotracer [(18)F]-P6 was selectively taken up by COX-1-expressing ovarian carcinoma (OVCAR 3) tumor xenografts as compared with the normal leg muscle. Our results suggest that [(18)F]-P6 might be an useful radiotracer in preclinical and clinical settings for in vivo PET-CT imaging of tissues that express elevated levels of COX-1.
    European journal of medicinal chemistry 04/2014; 80C:562-568. · 3.27 Impact Factor
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    ABSTRACT: This publication is the 1st in a series of publications by the Expert Panel of the Flavor and Extract Manufacturers Assoc. summarizing the Panel's 3rd re-evaluation of Generally Recognized as Safe (GRAS) status referred to as the GRASr2 program. In 2011, the Panel initiated a comprehensive program to re-evaluate the safety of more than 2700 flavor ingredients that have previously met the criteria for GRAS status under conditions of intended use as flavor ingredients. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics, and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances as flavoring ingredients are evaluated. The group of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances was reaffirmed as GRAS (GRASr2) based, in part, on their rapid absorption, metabolic detoxication, and excretion in humans and other animals; their low level of flavor use; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic studies and the lack of significant genotoxic and mutagenic potential.
    Journal of Food Science 04/2014; · 1.78 Impact Factor
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    ABSTRACT: Fluorocoxib A is an effective COX-2-targeted optical imaging agent, used for in vivo detection of inflammatory tissues and premalignant and malignant tumors that express elevated levels of COX-2 (Uddin et al. Cancer Res. 2010, 70, 3618–3627). In an effort to discover novel optical probes for COX-2, a trifluoromethyl analogue of fluorocoxib A (CF3-fluorocoxib A) was synthesized and evaluated for its ability to inhibit COX-2 in vitro purified enzyme and human cancer cell lines. Kinetic analysis revealed that CF3-fluorocoxib A is a slow, tight binding inhibitor of COX-2 that exhibits low nanomolar inhibitory potency. While CF3-fluorocoxib A and fluorocoxib A are similar in structure, CF3-fluorocoxib A shows improved potency in inhibition of wtCOX-2 and with a series of site-directed COX-2 mutants. After intraperitoneal injection, selective uptake of CF3-fluorocoxib A is detected in inflamed mouse paws compared to noninflamed contralateral paws by optical imaging, and uptake is blocked by pretreatment with the COX-2 inhibitor, celecoxib. Selective uptake is also detected in the COX-2-positive human tumor xenografts (1483 HNSCC) as compared with the COX-2-negative tumor xenografts (HCT116) in an in vivo nude mouse tumor model. These in vitro and in vivo studies suggest that binding to COX-2 is the major determinant of uptake of CF3-fluorocoxib A into the inflamed tissues and tumor xenografts. Thus, this new COX-2-targeted imaging probe should find utility in the detection and evaluation of COX-2 status in naturally occurring malignancies.
    ACS Medicinal Chemistry Letters 01/2014; 5(4):446–450. · 3.31 Impact Factor
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    ABSTRACT: Protein alkylation by reactive electrophiles contributes to chemical toxicities and oxidative stress, but the functional impact of alkylation damage across proteomes is poorly understood. We used Click chemistry and shotgun proteomics to profile the accumulation of proteome damage in human cells treated with lipid electrophile probes. Protein target profiles revealed three damage susceptibility classes, as well as proteins that were highly resistant to alkylation. Damage occurred selectively across functional protein interaction networks, with the most highly alkylation-susceptible proteins mapping to networks involved in cytoskeletal regulation. Proteins with lower damage susceptibility mapped to networks involved in protein synthesis and turnover and were alkylated only at electrophile concentrations that caused significant toxicity. Hierarchical susceptibility of proteome systems to alkylation may allow cells to survive sublethal damage while protecting critical cell functions.
    Molecular &amp Cellular Proteomics 01/2014; · 7.25 Impact Factor
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    ABSTRACT: Oxicams are widely used non-steroidal anti-inflammatory drugs (NSAIDs), but little is known about the molecular basis of the interaction with their target enzymes, the cyclooxygenases (COX). Isoxicam is a non-selective inhibitor of COX-1 and COX-2 whereas meloxicam displays some selectivity for COX-2. Here we report crystal complexes of COX-2 with isoxicam and meloxicam at 2.0 angstroms and 2.45 angstroms, respectively, and a crystal complex of COX-1 with meloxicam at 2.4 angstroms. These structures reveal that the oxicams bind to the active site of COX-2 using a binding pose not seen with other NSAIDs through two highly coordinated water molecules. The 4-hydroxyl group on the thiazine ring partners with Ser-530 via hydrogen bonding and the heteroatom of the carboxamide ring of the oxicam scaffold interacts with Tyr-385 and Ser-530 through a highly coordinated water molecule. The nitrogen atom of the thiazine and the oxygen atom of the carboxamide bind to Arg-120 and Tyr-355 via another highly ordered water molecule. The rotation of Leu-531 in the structure opens a novel-binding pocket, which is not utilized for the binding of other NSAIDs. In addition, a detailed study of meloxicam-COX-2 interactions revealed that mutation of Val-434 to Ile significantly reduces inhibition by meloxicam due to subtle changes around Phe-518, giving rise to the preferential inhibition of COX-2 over COX-1.
    Journal of Biological Chemistry 01/2014; · 4.65 Impact Factor
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    ABSTRACT: Stress is a major risk factor for the development of mood and anxiety disorders; elucidation of novel approaches to mitigate the deleterious effects of stress could have broad clinical applications. Pharmacological augmentation of central endogenous cannabinoid (eCB) signaling may be an effective therapeutic strategy to mitigate the adverse behavioral and physiological consequences of stress. Here we show that acute foot-shock stress induces a transient anxiety state measured 24 h later using the light-dark box assay and novelty-induced hypophagia test. Acute pharmacological inhibition of the anandamide-degrading enzyme, fatty acid amide hydrolase (FAAH), reverses the stress-induced anxiety state in a cannabinoid receptor-dependent manner. FAAH inhibition does not significantly affect anxiety-like behaviors in non-stressed mice. Moreover, whole brain anandamide levels are reduced 24 h after acute foot-shock stress and are negatively correlated with anxiety-like behavioral measures in the light-dark box test. These data indicate that central anandamide levels predict acute stress-induced anxiety, and that reversal of stress-induced anandamide deficiency is a key mechanism subserving the therapeutic effects of FAAH inhibition. These studies provide further support that eCB-augmentation is a viable pharmacological strategy for the treatment of stress-related neuropsychiatric disorders.
    Translational psychiatry. 01/2014; 4:e408.
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    Sarah C Shuck, Kristie L Rose, Lawrence J Marnett
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    ABSTRACT: Electrophilic DNA adducts produced following oxidative stress can form DNA-protein cross-links (DPCs), dramatically altering genomic maintenance pathways. Complete characterization of DPCs has been hindered, in part, because of a lack of comprehensive techniques for their analysis. We have, therefore, established a proteomics approach to investigate sites of cross-link formation using N(6)-(3-oxo-1-propenyl)-2'-deoxyadenosine (OPdA), an electrophilic DNA adduct produced from oxidative stress. OPdA was reacted with albumin and reduced with NaBH4 to stabilize DPCs. Using LC-MS/MS proteomics techniques, high-resolution peptide sequence data were obtained; however, using a database searching strategy, adducted peptides were only identified in samples subjected to chemical depurination. This strategy revealed multiple oxopropenyl adenine-lysine adducts and oxopropenyl-lysine adducts with the most reactive lysines identified to be Lys256 and Lys548. Manual interrogation of the mass spectral data provided evidence of OPdA deoxynucleoside conjugates to lysines and cross-links that underwent facile collision-induced dissociation to release an unmodified peptide without subsequent fragmentation. These fragmentations precluded adduct detection and peptide sequencing using database searching methods. Thus, comprehensive analysis of DPCs requires chemical depurination of DNA-protein reaction mixtures followed by a combination of database-dependent and manual interrogation of LC-MS/MS data using higher-energy collision-induced dissociation. In the present case, this approach revealed that OPdA selectively modifies surface lysine residues and produces nucleoside-protein cross-links and oxopropenyl lysine.
    Chemical Research in Toxicology 12/2013; · 3.67 Impact Factor
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    ABSTRACT: The oxidative stress products malondialdehyde and base propenal react with DNA bases forming the adduction products 3-(2'-deoxy-beta-D-erythro-pentofuranosyl)pyrimido[1,2-alpha]purin-10(3H)-one (M1dG) and N6-(oxypropenyl)-2'-deoxyadenosine (OPdA). M1dG is mutagenic in vivo and miscodes in vitro, but little work has been done on OPdA. To further our understanding of the effect of OPdA on polymerase activity and mutagenicity, we evaluated the ability of the translesion DNA polymerases hPols η, κ, and ι to bypass OPdA in vitro. hPols η and κ inserted dNTPs opposite the lesion and extended the OPdA-modified primer to the terminus. hPol ι inserted dNTPs opposite OPdA but failed to fully extend the primer. Steady-state kinetic analysis indicated that these polymerases preferentially insert dTTP opposite OPdA, although less efficiently than opposite dA. Minimal incorrect base insertion was observed for all polymerases, and dCTP was the primary mis-insertion event. Examining replicative and repair polymerases revealed little effect of OPdA on the Sulfolobus solfataricus polymerase Dpo1 or the Klenow fragment of Escherichia coli DNA polymerase I. Bacteriophage T7 DNA polymerase displayed reduced OPdA bypass compared to unmodified DNA, and OPdA nearly completely blocked the activity of base excision repair polymerase hPol β. This work demonstrates that bypass of OPdA is generally error-free, modestly decreases the catalytic activity of most polymerases, and blocks hPol β polymerase activity. Although mis-insertion opposite OPdA is relatively weak, the efficiency of bypass may introduce A → G transitions observed in vivo.
    Biochemistry 10/2013; · 3.38 Impact Factor
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    ABSTRACT: Reactive electrophiles produced during oxidative stress, such as 4-hydroxynonenal (HNE), are increasingly recognized as contributing factors in a variety of degenerative and inflammatory diseases. Here we used the RNA-seq technology to characterize transcriptome responses in RKO cells induced by HNE at subcytotoxic and cytotoxic doses. RNA-seq analysis rediscovered most of the differentially expressed genes reported by microarray studies and also identified novel gene responses. Interestingly, differential expression detection at the coding DNA sequence (CDS) level helped to further improve the consistency between the two technologies, suggesting the utility and importance of the CDS level analysis. RNA-seq data analysis combining gene and CDS levels yielded an informative and comprehensive picture of gradually evolving response networks with increasing HNE doses, from cell protection against oxidative injury at low dose, initiation of cell apoptosis and DNA damage at intermediate dose to significant deregulation of cellular functions at high dose. These evolving dose-dependent pathway changes, which cannot be observed by the gene level analysis alone, clearly reveal the HNE cytotoxic effect and are supported by IC50 experiments. Additionally, differential expression at the CDS level provides new insights into isoform regulation mechanisms. Taken together, our data demonstrate the power of RNA-seq to identify subtle transcriptome changes and to characterize effects induced by HNE through the generation of high-resolution data coupled with differential analysis at both gene and CDS levels.
    Molecular BioSystems 09/2013; · 3.35 Impact Factor
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    ABSTRACT: Lumiracoxib is a substrate-selective inhibitor of endocannabinoid oxygenation by cyclooxygenase-2 (COX-2). We assayed a series of lumiracoxib derivatives to identify the structural determinants of substrate-selective inhibition. The hydrogen-bonding potential of the substituents at the ortho positions of the aniline ring dictated the potency and substrate selectivity of the inhibitors. The presence of a 5'-methyl group on the phenylacetic acid ring increased the potency of molecules with a single ortho substituent. Des-fluorolumiracoxib (2) was the most potent and selective inhibitor of endocannabinoid oxygenation. The positioning of critical substituents in the binding site was identified from a 2.35Å crystal structure of lumiracoxib bound to COX-2.
    Bioorganic & medicinal chemistry letters 09/2013; · 2.65 Impact Factor
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    ABSTRACT: Augmentation of endogenous cannabinoid (eCB) signaling represents an emerging approach to the treatment of affective disorders. Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid to form prostaglandins, but also inactivates eCBs in vitro. However, the viability of COX-2 as a therapeutic target for in vivo eCB augmentation has not been explored. Using medicinal chemistry and in vivo analytical and behavioral pharmacological approaches, we found that COX-2 is important for the regulation of eCB levels in vivo. We used a pharmacological strategy involving substrate-selective inhibition of COX-2 to augment eCB signaling without affecting related non-eCB lipids or prostaglandin synthesis. Behaviorally, substrate-selective inhibition of COX-2 reduced anxiety-like behaviors in mice via increased eCB signaling. Our data suggest a key role for COX-2 in the regulation of eCB signaling and indicate that substrate-selective pharmacology represents a viable approach for eCB augmentation with broad therapeutic potential.
    Nature Neuroscience 08/2013; · 15.25 Impact Factor
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    ABSTRACT: Oxidized phospholipids (oxPLs) generated non-enzymatically display pleiotropic biological actions in inflammation. Their generation by cellular cyclooxygenases (COX) is currently unknown. To determine whether platelets generate prostaglandin (PG)-containing oxPLs, then characterize their structures and mechanisms of formation, we applied precursor scanning- tandem mass spectrometry to lipid extracts of agonist-activated human platelets. Thrombin, collagen or ionophore activation stimulated generation of families of PGs, comprising PGE2 and D2 attached to four phosphatidylethanolamine (PE) phospholipids (16:0p/, 18:1p/, 18:0p/ and 18:0a/). They formed within 2-5 min of activation in a calcium, phospholipase C, p38 MAP kinases, MEK1, cPLA2, and src tyrosine kinase-dependent manner (28.1 +/- 2.3 pg/2E8 platelets). Unlike free PGs, they remained cell associated, suggesting an autocrine mode of action. Their generation was inhibited by in vivo aspirin supplementation (75 mg/day), or in vitro cyclooxygenase-1 (COX-1) blockade. Inhibitors of fatty acyl re-esterification blocked generation significantly, while purified COX-1 was unable to directly oxidize PE in vitro. This indicates that they form in platelets via rapid esterification of COX-1 derived PGE2/D2 into PE. In summary, COX-1 in human platelets acutely mediates membrane phospholipid oxidation via formation of PG-esterified PLs, in response to pathophysiological agonists.
    The Journal of Lipid Research 07/2013; · 4.39 Impact Factor
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    ABSTRACT: Abstract α-Aminocarbonyl metabolites (e.g., 5-aminolevulinic acid and aminoacetone) and the wide spectrum microbicide 1,4-diamino-2-butanone (DAB) have been shown to exhibit pro-oxidant properties. In vitro, these compounds undergo phosphate-catalyzed enolization at physiological pH and subsequent superoxide radical-propagated aerobic oxidation, yielding a reactive α-oxoaldehyde and H2O2. DAB cytotoxicity to pathogenic microorganisms has been attributed to the inhibition of polyamine biosynthesis. However, the role played in cell death by reactive DAB oxidation products is still poorly understood. This work aims to clarify the mechanism of DAB-promoted pro-oxidant action on mammalian cells. DAB (0.05-10 mM) treatment of RKO cells derived from human colon carcinoma led to a decrease in cell viability (IC50 ca. 0.3 mM DAB, 24 h incubation). Pre-addition of either catalase (5 µM) or aminoguanidine (20 mM) was observed to partially inhibit the toxic effects of DAB to the cells, while N-acetyl-L-cysteine (NAC, 5 mM) or reduced glutathione (GSH, 5 mM) provided almost complete protection against DAB. Changes in redox balance and stress response pathways were indicated by the increased expression of HO-1, NQO1 and xCT. Moreover, the observation of caspase 3 and PARP cleavage products is consistent with DAB-triggered apoptosis in RKO cells, which was corroborated by the partial protection afforded by the pan caspase inhibitor z-VAD-FMK. Finally, DAB treatment disrupted the cell cycle in response to increased p53 and activation of ATM. Altogether, these data support the hypothesis that DAB exerts cytotoxicity via a mechanism involving not only polyamine biosynthesis but also by DAB oxidation products.
    Free Radical Research 06/2013; · 3.28 Impact Factor

Publication Stats

14k Citations
2,293.80 Total Impact Points


  • 1990–2014
    • Vanderbilt University
      • • Department of Biochemistry
      • • Center in Molecular Toxicology
      • • Department of Pediatrics
      Nashville, Michigan, United States
  • 2013
    • Technische Universität Dresden
      Dresden, Saxony, Germany
    • Cardiff University
      Cardiff, Wales, United Kingdom
    • University of Tennessee
      • College of Veterinary Medicine
      Knoxville, TN, United States
  • 2012
    • The University of Tennessee Medical Center at Knoxville
      Knoxville, Tennessee, United States
  • 2011–2012
    • University of Leipzig
      • Institut für Anorganische Chemie
      Leipzig, Saxony, Germany
  • 2005–2007
    • University of Wales
      Cardiff, Wales, United Kingdom
    • The American Society for Biochemistry and Molecular Biology
      Nashville, Tennessee, United States
  • 2004
    • Imperial College London
      • Section of Pharmacology and Toxicology
      London, ENG, United Kingdom
  • 2001–2003
    • Gateway-Vanderbilt Cancer Treatment Center
      Clarksville, Tennessee, United States
    • Johns Hopkins University
      Baltimore, Maryland, United States
  • 1977–2002
    • Wayne State University
      • • Department of Chemistry
      • • Department of Radiation Oncology
      Detroit, MI, United States
  • 1998–2001
    • University of Leicester
      • Medical Research Council Toxicology Unit
      Leicester, ENG, United Kingdom
    • Massachusetts Institute of Technology
      • Division of Toxicology
      Cambridge, Massachusetts, United States
  • 1991–1997
    • National Institutes of Health
      • • Chemical Biology Laboratory
      • • Laboratory of Molecular Biology
      Bethesda, MD, United States
  • 1994
    • University of Adelaide
      • Discipline of Clinical and Experimental Pharmacology
      Adelaide, South Australia, Australia
    • American Cancer Society
      Atlanta, Georgia, United States
  • 1988
    • University of Texas MD Anderson Cancer Center
      Houston, Texas, United States
    • University of Illinois, Urbana-Champaign
      • Department of Biochemistry
      Urbana, IL, United States
  • 1986
    • University of Alberta
      • Department of Chemistry
      Edmonton, Alberta, Canada
  • 1983
    • Oakland University
      • Department of Chemistry
      Rochester, MI, United States
  • 1980
    • Duke University
      • Department of Chemistry
      Durham, North Carolina, United States