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Chakraborty P, Farhat K, Po SS, Armoundas AA, Stavrakis S. Autonomic Nervous System and Cardiac Metabolism: Links Between Autonomic and Metabolic Remodeling in Atrial Fibrillation. JACC Clin Electrophysiol 2023:S2405-500X(23)00117-2. [PMID: 37086229 DOI: 10.1016/j.jacep.2023.02.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/27/2023] [Accepted: 02/16/2023] [Indexed: 04/23/2023]
Abstract
Simultaneous activation of the sympathetic and parasympathetic nervous systems is crucial for the initiation of paroxysmal atrial fibrillation (AF). However, unbalanced activation of the sympathetic system is characteristic of autonomic remodeling in long-standing persistent AF. Moreover, the adrenergic activation-induced metabolic derangements provide a milieu for acute AF and promote the transition from the paroxysmal to the persistent phase of AF. On the other hand, cholinergic activation ameliorates the maladaptive metabolic remodeling in the face of metabolic challenges. Selective inhibition of the sympathetic system and restoration of the balance of the cholinergic system by neuromodulation is emerging as a novel nonpharmacologic strategy for managing AF. This review explores the link between cardiac autonomic and metabolic remodeling and the potential roles of different autonomic modulation strategies on atrial metabolic aberrations in AF.
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Affiliation(s)
- Praloy Chakraborty
- Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Kassem Farhat
- Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Sunny S Po
- Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Antonis A Armoundas
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts, USA; Broad Institute, Massachusetts Institute of Technology, Boston, Massachusetts, USA
| | - Stavros Stavrakis
- Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
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2
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Tulen CBM, Snow SJ, Leermakers PA, Kodavanti UP, van Schooten FJ, Opperhuizen A, Remels AHV. Acrolein inhalation acutely affects the regulation of mitochondrial metabolism in rat lung. Toxicology 2022; 469:153129. [PMID: 35150775 PMCID: PMC9201729 DOI: 10.1016/j.tox.2022.153129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 10/19/2022]
Abstract
Exposure of the airways to cigarette smoke (CS) is the primary risk factor for developing several lung diseases such as Chronic Obstructive Pulmonary Disease (COPD). CS consists of a complex mixture of over 6000 chemicals including the highly reactive α,β-unsaturated aldehyde acrolein. Acrolein is thought to be responsible for a large proportion of the non-cancer disease risk associated with smoking. Emerging evidence suggest a key role for CS-induced abnormalities in mitochondrial morphology and function in airway epithelial cells in COPD pathogenesis. Although in vitro studies suggest acrolein-induced mitochondrial dysfunction in airway epithelial cells, it is unknown if in vivo inhalation of acrolein affects mitochondrial content or the pathways controlling this. In this study, rats were acutely exposed to acrolein by inhalation (nose-only; 0-4 ppm), 4 h/day for 1 or 2 consecutive days (n = 6/group). Subsequently, the activity and abundance of key constituents of mitochondrial metabolic pathways as well as expression of critical proteins and genes controlling mitochondrial biogenesis and mitophagy were investigated in lung homogenates. A transient decreasing response in protein and transcript abundance of subunits of the electron transport chain complexes was observed following acrolein inhalation. Moreover, acrolein inhalation caused a decreased abundance of key regulators associated with mitochondrial biogenesis, respectively a differential response on day 1 versus day 2. Abundance of components of the mitophagy machinery was in general unaltered in response to acrolein exposure in rat lung. Collectively, this study demonstrates that acrolein inhalation acutely and dose-dependently disrupts the molecular regulation of mitochondrial metabolism in rat lung. Hence, understanding the effect of acrolein on mitochondrial function will provide a scientifically supported reasoning to shortlist aldehydes regulation in tobacco smoke.
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Affiliation(s)
- C B M Tulen
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Department of Pharmacology and Toxicology, Maastricht University Medical Center+, Maastricht, the Netherlands.
| | - S J Snow
- Public Health and Integrated Toxicology Division, Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Durham, NC, United States; ICF, Durham, NC, United States
| | - P A Leermakers
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Department of Pharmacology and Toxicology, Maastricht University Medical Center+, Maastricht, the Netherlands
| | - U P Kodavanti
- Public Health and Integrated Toxicology Division, Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Durham, NC, United States; Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - F J van Schooten
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Department of Pharmacology and Toxicology, Maastricht University Medical Center+, Maastricht, the Netherlands
| | - A Opperhuizen
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Department of Pharmacology and Toxicology, Maastricht University Medical Center+, Maastricht, the Netherlands; Netherlands Food and Consumer Product Safety Authority (NVWA), Utrecht, the Netherlands
| | - A H V Remels
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Department of Pharmacology and Toxicology, Maastricht University Medical Center+, Maastricht, the Netherlands
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Clapp PW, Lavrich KS, van Heusden CA, Lazarowski ER, Carson JL, Jaspers I. Cinnamaldehyde in flavored e-cigarette liquids temporarily suppresses bronchial epithelial cell ciliary motility by dysregulation of mitochondrial function. Am J Physiol Lung Cell Mol Physiol 2019; 316:L470-L486. [PMID: 30604630 PMCID: PMC6459291 DOI: 10.1152/ajplung.00304.2018] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 12/21/2018] [Accepted: 12/21/2018] [Indexed: 01/23/2023] Open
Abstract
Aldehydes in cigarette smoke (CS) impair mitochondrial function and reduce ciliary beat frequency (CBF), leading to diminished mucociliary clearance (MCC). However, the effects of aldehyde e-cigarette flavorings on CBF are unknown. The purpose of this study was to investigate whether cinnamaldehyde, a flavoring agent commonly used in e-cigarettes, disrupts mitochondrial function and impairs CBF on well-differentiated human bronchial epithelial (hBE) cells. To this end, hBE cells were exposed to diluted cinnamon-flavored e-liquids and vaped aerosol and assessed for changes in CBF. hBE cells were subsequently exposed to various concentrations of cinnamaldehyde to establish a dose-response relationship for effects on CBF. Changes in mitochondrial oxidative phosphorylation and glycolysis were evaluated by Seahorse Extracellular Flux Analyzer, and adenine nucleotide levels were quantified by HPLC. Both cinnamaldehyde-containing e-liquid and vaped aerosol rapidly yet transiently suppressed CBF, and exposure to cinnamaldehyde alone recapitulated this effect. Cinnamaldehyde impaired mitochondrial respiration and glycolysis in a dose-dependent manner, and intracellular ATP levels were significantly but temporarily reduced following exposure. Addition of nicotine had no effect on the cinnamaldehyde-induced suppression of CBF or mitochondrial function. These data indicate that cinnamaldehyde rapidly disrupts mitochondrial function, inhibits bioenergetic processes, and reduces ATP levels, which correlates with impaired CBF. Because normal ciliary motility and MCC are essential respiratory defenses, inhalation of cinnamaldehyde may increase the risk of respiratory infections in e-cigarette users.
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Affiliation(s)
- Phillip W Clapp
- Curriculum in Toxicology, School of Medicine, University of North Carolina , Chapel Hill, North Carolina
- Center for Environmental Medicine, Asthma, and Lung Biology, School of Medicine, University of North Carolina , Chapel Hill, North Carolina
| | - Katelyn S Lavrich
- Curriculum in Toxicology, School of Medicine, University of North Carolina , Chapel Hill, North Carolina
| | | | - Eduardo R Lazarowski
- Department of Medicine, University of North Carolina , Chapel Hill, North Carolina
| | - Johnny L Carson
- Center for Environmental Medicine, Asthma, and Lung Biology, School of Medicine, University of North Carolina , Chapel Hill, North Carolina
- Department of Pediatrics, University of North Carolina , Chapel Hill, North Carolina
| | - Ilona Jaspers
- Curriculum in Toxicology, School of Medicine, University of North Carolina , Chapel Hill, North Carolina
- Center for Environmental Medicine, Asthma, and Lung Biology, School of Medicine, University of North Carolina , Chapel Hill, North Carolina
- Department of Pediatrics, University of North Carolina , Chapel Hill, North Carolina
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4
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Mapanga RF, Essop MF. Damaging effects of hyperglycemia on cardiovascular function: spotlight on glucose metabolic pathways. Am J Physiol Heart Circ Physiol 2016; 310:H153-73. [DOI: 10.1152/ajpheart.00206.2015] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 10/27/2015] [Indexed: 12/13/2022]
Abstract
The incidence of cardiovascular complications associated with hyperglycemia is a growing global health problem. This review discusses the link between hyperglycemia and cardiovascular diseases onset, focusing on the role of recently emerging downstream mediators, namely, oxidative stress and glucose metabolic pathway perturbations. The role of hyperglycemia-mediated activation of nonoxidative glucose pathways (NOGPs) [i.e., the polyol pathway, hexosamine biosynthetic pathway, advanced glycation end products (AGEs), and protein kinase C] in this process is extensively reviewed. The proposal is made that there is a unique interplay between NOGPs and a downstream convergence of detrimental effects that especially affect cardiac endothelial cells, thereby contributing to contractile dysfunction. In this process the AGE pathway emerges as a crucial mediator of hyperglycemia-mediated detrimental effects. In addition, a vicious metabolic cycle is established whereby hyperglycemia-induced NOGPs further fuel their own activation by generating even more oxidative stress, thereby exacerbating damaging effects on cardiac function. Thus NOGP inhibition, and particularly that of the AGE pathway, emerges as a novel therapeutic intervention for the treatment of cardiovascular complications such as acute myocardial infarction in the presence hyperglycemia.
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Affiliation(s)
- Rudo F. Mapanga
- Cardio-Metabolic Research Group, Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - M. Faadiel Essop
- Cardio-Metabolic Research Group, Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
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5
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Chakraborty M, Fry JD. Evidence that Environmental Heterogeneity Maintains a Detoxifying Enzyme Polymorphism in Drosophila melanogaster. Curr Biol 2015; 26:219-223. [PMID: 26748852 DOI: 10.1016/j.cub.2015.11.049] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/09/2015] [Accepted: 11/11/2015] [Indexed: 11/28/2022]
Abstract
Environmental heterogeneity is thought to be an important process maintaining genetic variation in populations [1-4]: if alternative alleles are favored in different environments, a stable polymorphism can be maintained [1, 5, 6]. This situation has been hypothesized to occur in genes encoding multi-substrate enzymes [7], in which changes that increase activity with one substrate typically decrease activity with others [8-10], but examples of polymorphisms maintained by this mechanism are rare. Here, we present evidence that a polymorphism in an enzyme gene in Drosophila melanogaster is maintained by such a trade-off. The mitochondrially localized aldehyde dehydrogenase in D. melanogaster has two important functions: detoxifying acetaldehyde derived from dietary ethanol [11] and detoxifying larger aldehydes produced as byproducts of oxidative phosphorylation [12]. A derived variant of the enzyme, Leu479Phe, is present in moderate frequencies in most temperate populations but is rare in more ethanol-averse tropical populations. Using purified recombinant protein, we show that the Leu-Phe substitution increases turnover rate of acetaldehyde but decreases turnover rate of larger aldehydes. Furthermore, using transgenic fly lines, we show that the substitution increases lifetime fitness on medium supplemented with an ecologically relevant ethanol concentration but decreases fitness on medium lacking ethanol. The strong, opposing selection pressures, coupled with documented highly variable ethanol concentrations in breeding sites of temperate populations, implicate an essential role for environmental heterogeneity in maintaining the polymorphism.
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Affiliation(s)
- Mahul Chakraborty
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - James D Fry
- Department of Biology, University of Rochester, Rochester, NY 14627, USA.
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6
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Patel SN, Parikh M, Lau-Cam CA. Impact of light ethanol intake and of taurine, separately and together, on pathways of glucose metabolism in the kidney of diabetic rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 803:279-303. [PMID: 25833505 DOI: 10.1007/978-3-319-15126-7_23] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sanket N Patel
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Jamaica, NY, USA
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7
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Quin GJ, Lyons B, Len ACL, Madigan MC, Gillies MC. Proteome changes induced by laser in diabetic retinopathy. Clin Exp Ophthalmol 2014; 43:180-7. [DOI: 10.1111/ceo.12372] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/14/2014] [Indexed: 12/01/2022]
Affiliation(s)
- Godfrey J Quin
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
- Australian School of Advanced Medicine; Macquarie University; Sydney New South Wales Australia
| | - Brian Lyons
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
| | - Alice CL Len
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
| | - Michele C Madigan
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
- School of Optometry and Vision Science; University of New South Wales; Sydney New South Wales Australia
| | - Mark C Gillies
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
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8
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Abstract
Altered glucose metabolism due to insulin resistance is a common feature of essential hypertension in humans and in animal models. Elevated endogenous aldehydes in genetic (spontaneously hypertensive rats) and acquired (fructose-induced hypertensive rats) models of essential hypertension may be due to increased production of the reactive aldehyde methylglyoxal, resulting from altered glucose metabolism. Excess methylglyoxal binds sulfhydryl groups of membrane proteins, altering calcium channels and increasing cytosolic free Ca(2+) and blood pressure. It has been demonstrated that methylglyoxal, when given in drinking water to Wistar-Kyoto rats, leads to an increase in kidney aldehyde conjugates, cytosolic free Ca(2+) concentration, decreased serum nitric oxide, renal vascular hyperplasia and hypertension. N-acetylcysteine (NAC) in the diet of these animals prevented hypertension and associated biochemical and morphological changes. NAC normalizes blood pressure by directly binding to excess methylglyoxal, thus normalizing Ca(2+) channels, cytosolic Ca(2+) and nitric oxide. NAC also leads to increased levels of tissue glutathione, a storage form of cysteine. Glutathione acts as a cofactor in the enzymatic catabolism of methylglyoxal. Cysteine and other antioxidants, such as vitamins B(6), C and E, and lipoic acid, prevented hypertension and associated biochemical and morphological changes in both genetic and acquired rat models of hypertension. The antihypertensive effect of dietary antioxidants may be due to an increase in tissue cysteine and glutathione, which improves glucose metabolism and decreases tissue methylglyoxal. A diet rich in these antioxidants may be effective in preventing and controlling hypertension in humans.
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Affiliation(s)
- Sudesh Vasdev
- Discipline of Medicine, Faculty of Medicine, Health Sciences Centre, Memorial University, St John's, Newfoundland and Labrador
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Morita N, Lee JH, Bapat A, Fishbein MC, Mandel WJ, Chen PS, Weiss JN, Karagueuzian HS. Glycolytic inhibition causes spontaneous ventricular fibrillation in aged hearts. Am J Physiol Heart Circ Physiol 2011; 301:H180-91. [PMID: 21478408 DOI: 10.1152/ajpheart.00128.2011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Selective glycolytic inhibition (GI) promotes electromechanical alternans and triggered beats in isolated cardiac myocytes. We sought to determine whether GI promotes triggered activity by early afterdepolarization (EAD) or delayed afterdepolarizations in intact hearts isolated from adult and aged rats. Dual voltage and intracellular calcium ion (Ca(i)(2+)) fluorescent optical maps and single cell glass microelectrode recordings were made from the left ventricular (LV) epicardium of isolated Langendorff-perfused adult (∼4 mo) and aged (∼24 mo) rat hearts. GI was induced by replacing glucose with 10 mM pyruvate in oxygenated Tyrode's. Within 20 min, GI slowed Ca(i)(2+) transient decline rate and shortened action potential duration in both groups. These changes were associated with ventricular fibrillation (VF) in the aged hearts (64 out of 66) but not in adult hearts (0 out of 18; P < 0.001). VF was preceded by a transient period of focal ventricular tachycardia caused by EAD-mediated triggered activity leading to VF within seconds. The VF was suppressed by the ATP-sensitive K (K(ATP)) channel blocker glibenclamide (1 μM) but not (0 out of 7) by mitochondrial K(ATP) block. The Ca-calmodulin-dependent protein kinase II (CaMKII) blocker KN-93 (1 μM) prevented GI-mediated VF (P < 0.05). Block of Na-Ca exchanger (NCX) by SEA0400 (2 μM) prevented GI-mediated VF (3 out of 6), provided significant bradycardia did not occur. Aged hearts had significantly greater LV fibrosis and reduced connexin 43 than adult hearts (P < 0.05). We conclude that in aged fibrotic unlike in adult rat hearts, GI promotes EADs, triggered activity, and VF by activation of K(ATP) channels CaMKII and NCX.
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Affiliation(s)
- Norishige Morita
- Translational Arrhythmia Research Section, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 675 Charles E. Young Dr. South, MRL 3645 Mail Code: 176022, Los Angeles, CA 90095, USA
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10
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Schlisser AE, Yan J, Hales BF. Teratogen-induced oxidative stress targets glyceraldehyde-3-phosphate dehydrogenase in the organogenesis stage mouse embryo. Toxicol Sci 2010; 118:686-95. [PMID: 20889679 PMCID: PMC2984529 DOI: 10.1093/toxsci/kfq287] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Exposure during the organogenesis stage of the mouse embryo to the model teratogen, hydroxyurea (HU), induces curly tail and limb malformations. Oxidative stress contributes to the developmental toxicity of HU. Reactive oxygen species (ROS) interact with polyunsaturated bilipid membranes to form α,β-unsaturated reactive aldehydes; 4-hydroxy-2-nonenal (4-HNE), one of the most cytotoxic of these aldehydes, covalently adducts with proteins, lipids, and nucleic acids. The goal of the current study is to determine if HU exposure of CD1 mice on gestation day 9 generates region-specific 4-HNE-protein adducts in the embryo and to identify the proteins targeted. The formation of 4-HNE-protein adducts was elevated in the caudal region of control embryos; HU exposure further increased 4-HNE-protein adduct formation in this area. Interestingly, three of the 4-HNE–modified proteins, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glutamate oxaloacetate transaminase 2, and aldolase 1, A isoform, are involved in energy metabolism. The formation of 4-HNE-GAPDH protein adducts reduced GAPDH enzymatic activity by 20% and attenuated lactate production by 40%. Furthermore, HU exposure induced the nuclear translocation of GAPDH in the caudal region of exposed embryos; this nuclear translocation may be associated with the reactivation of oxidized proteins involved in DNA repair, such as apurinic/apyrimidinic endonuclease-1, and the stimulation of E1A-associated P300 protein/creb-binding protein (p300/CBP) activity, initiating cell death in a p53-dependent pathway. We propose that GAPDH is a redox-sensitive target in the embryo and may play a role in a stress response during development.
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Affiliation(s)
- Ava E Schlisser
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada H3G 1Y6
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Novotny MV, Soini HA, Mechref Y. Biochemical individuality reflected in chromatographic, electrophoretic and mass-spectrometric profiles. J Chromatogr B Analyt Technol Biomed Life Sci 2008; 866:26-47. [PMID: 18551752 PMCID: PMC2603028 DOI: 10.1016/j.jchromb.2007.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This review discusses the current trends in molecular profiling for the emerging systems biology applications. Historically, the methodological developments in separation science were coincident with the availability of new ionization techniques in mass spectrometry. Coupling miniaturized separation techniques with technologically-advanced MS instrumentation and the modern data processing capabilities are at the heart of current platforms for proteomics, glycomics and metabolomics. These are being featured here by the examples from quantitative proteomics, glycan mapping and metabolomic profiling of physiological fluids.
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Affiliation(s)
- Milos V Novotny
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA.
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12
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Gardiner NJ, Wang Z, Luke C, Gott A, Price SA, Fernyhough P. Expression of hexokinase isoforms in the dorsal root ganglion of the adult rat and effect of experimental diabetes. Brain Res 2007; 1175:143-54. [PMID: 17803972 DOI: 10.1016/j.brainres.2007.08.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 07/31/2007] [Accepted: 08/02/2007] [Indexed: 11/21/2022]
Abstract
The effect of streptozotocin (STZ)-induced diabetes on expression and activity of hexokinase, the first enzyme and rate-limiting step in glycolysis, was studied in sensory neurons of lumbar dorsal root ganglia (DRG). The DRG and sciatic nerve of adult rats expressed the hexokinase I isoform only. Immunofluorescent staining of lumbar DRG demonstrated that small-medium neurons and satellite cells exhibited high levels of expression of hexokinase I. Large, mainly proprioceptive neurons, had very low or negative staining for hexokinase I. Intracellular localization and biochemical studies on intact DRG from adult rats and cultured adult rat sensory neurons revealed that hexokinase I was almost exclusively found in the mitochondrial compartment. Duration of STZ-diabetes of 6 or 12 weeks diminished hexokinase activity by 28% and 30%, respectively, in lumbar DRG compared with age matched controls (P<0.05). Quantitative Western blotting showed no effect of diabetes on hexokinase I protein expression in homogenates or mitochondrial preparations from DRG. Immunofluorescent staining for hexokinase I showed no diabetes-dependent change in small-medium neuron expression in DRG, however, large neurons became positive for hexokinase I (P<0.05). Such complex effects of diabetes on hexokinase I expression in the DRG may be due to glucose-driven up-regulation of expression or the result of impaired axonal transport and perikaryal accumulation in the large neuron sub-population. Because hexokinase is the rate-limiting enzyme of glycolysis these results imply that metabolic flux through the glycolytic pathway is reduced in diabetes. This finding, therefore, questions the role of high glucose-induced metabolic flux as a key driving force in reactive oxygen species generation by mitochondria.
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Affiliation(s)
- Natalie J Gardiner
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK
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Price SA, Zeef LAH, Wardleworth L, Hayes A, Tomlinson DR. Identification of changes in gene expression in dorsal root ganglia in diabetic neuropathy: correlation with functional deficits. J Neuropathol Exp Neurol 2006; 65:722-32. [PMID: 16825959 DOI: 10.1097/01.jnen.0000228199.89420.90] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
This study aimed to correlate the onset of functional deficits in diabetic neuropathy with changes in gene expression in rat dorsal root ganglia (DRG). After 1, 4, or 8 weeks of streptozotocin-induced diabetes, sensory and motor nerve conduction velocities (NCV) were measured as an indicator of neuropathy and changes in gene expression were measured using Affymetrix oligonucleotide microarrays. No significant changes in NCV were found after 1 week of diabetes, but after 4 and 8 weeks, there was a significant reduction in both sensory and motor NCV. Global gene expression changes in diabetic rat DRG were evident from principal component analysis of microarray data after 1, 4, and 8 weeks. Expression changes in individual genes were relatively small in line with a gradual degenerative neuropathy indirectly resulting from diabetes. Sets of differentially expressed genes have been identified and quantitative reverse transcriptase-polymerase chain reaction has been used to confirm the microarray data for several genes. Gene ontology overrepresentation analysis was performed on the microarray data to identify biologic processes altered in diabetic DRG. The genes identified in this study may be responsible for causing the functional deficits and suggest pathways/processes that require further investigation as possible targets for therapeutic intervention.
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Affiliation(s)
- Sally Amanda Price
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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Ono N, Hayashi H, Kawase A, Lin SF, Li H, Weiss JN, Chen PS, Karagueuzian HS. Spontaneous atrial fibrillation initiated by triggered activity near the pulmonary veins in aged rats subjected to glycolytic inhibition. Am J Physiol Heart Circ Physiol 2006; 292:H639-48. [PMID: 16920811 DOI: 10.1152/ajpheart.00445.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging and glycolytic inhibition (GI) are known to alter intracellular calcium ion (Ca(i)(2+)) handling in cardiac myocytes, causing early afterpotentials (EADs) and delayed afterpotentials. We hypothesized that aging and GI interact synergistically in intact hearts to generate EADs and triggered activity leading to atrial fibrillation (AF). We studied isolated and Langendorff-perfused hearts of young (age 3-5 mo, N = 8) and old (age 27-29 mo, N = 14) rats subjected to GI (0 glucose + 10 mmol/l pyruvate). Epicardial atrial activation maps were constructed using optical action potentials, while simultaneously monitoring Ca(i)(2+) by means of dual-voltage and calcium-sensitive fluorescent dyes. During GI, spontaneous AF occurred in 13 of 14 old but in no young rats. AF was initiated by EAD-induced triggered activity at the left atrial pulmonary vein junction (LA-PVJ). The triggered activity initially propagated as single wave front, but within 1 s degenerated into multiple wavelets. The EADs and triggered activity in the old atria were associated with significantly elevated diastolic Ca(i)(2+) levels at the LA-PVJ, where the time constant tau of the Ca(i)(2+) transient decline and action potential duration were significantly (P < 0.01) prolonged compared with atrial sites 5 mm away from LA-PVJ. During GI and rapid atrial pacing, spatially discordant APD and Ca(i)(2+) transient alternans developed in the old but not young atria, leading to AF. Atria in old rats had significantly more fibrotic tissue than atria in young rats. We conclude that GI interacts with the aged and fibrotic atria to amplify Ca(i)(2+) handling abnormalities that facilitate EAD-mediated triggered activity and AF.
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Affiliation(s)
- Norihiko Ono
- Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
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15
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Sango K, Suzuki T, Yanagisawa H, Takaku S, Hirooka H, Tamura M, Watabe K. High glucose-induced activation of the polyol pathway and changes of gene expression profiles in immortalized adult mouse Schwann cells IMS32. J Neurochem 2006; 98:446-58. [PMID: 16805838 DOI: 10.1111/j.1471-4159.2006.03885.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We investigated the polyol pathway activity and the gene expression profiles in immortalized adult mouse Schwann cells (IMS32) under normal (5.6 mM) and high (30 and 56 mM) glucose conditions for 7-14 days in culture. Messenger RNA and the protein expression of aldose reductase (AR) and the intracellular sorbitol and fructose contents were up-regulated in IMS32 under high glucose conditions compared with normal glucose conditions. By employing DNA microarray and subsequent RT-PCR/northern blot analyses, we observed significant up-regulation of the mRNA expressions for serum amyloid A3 (SAA3), angiopoietin-like 4 (ANGPTL4) and ecotropic viral integration site 3 (Evi3), and the down-regulation of aldehyde reductase (AKR1A4) mRNA expression in the cells under high glucose (30 mM) conditions. The application of an AR inhibitor, SNK-860, to the high glucose medium ameliorated the increased sorbitol and fructose contents and the reduced AKR1A4 mRNA expression, while it had no effect on mRNA expressions for SAA3, ANGPTL4 or Evi3. Considering that the exposure to the high glucose (>or= 30 mM) conditions mimicking hyperglycaemia in vivo accelerated the polyol pathway in IMS32, but not in other previously reported Schwann cells, the culture system of IMS32 under those conditions may provide novel findings about the polyol pathway-related abnormalities in diabetic neuropathy.
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Affiliation(s)
- Kazunori Sango
- Department of Developmental Morphology, Tokyo Metropolitan Institute for Neuroscience, Fuchu, Tokyo, Japan.
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16
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Reis A, Domingues MRM, Amado FML, Ferrer-Correia AJV, Domingues P. Identification of linoleic acid free radicals and other breakdown products using spin trapping with liquid chromatography-electrospray tandem mass spectrometry. Biomed Chromatogr 2005; 20:109-18. [PMID: 15981198 DOI: 10.1002/bmc.536] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Linoleic acid radical products formed by radical reaction (Fenton conditions) were trapped using 5,5-dimethyl-1-pyrrolidine-N-oxide (DMPO) and analysed by reversed-phase liquid chromatography coupled to electrospray mass spectrometry (LC-MS). The linoleic acid radical species detected as DMPO spin adducts comprised oxidized linoleic acid and short-chain radical species that resulted from the breakdown of carbon and oxygen centred radicals. Based on the m/z values, the short-chain products were identified as alkyl and carboxylic acid DMPO radical adducts that exhibited different elution times. The ions identified as DMPO radical adducts were studied by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The LC-MS/MS spectra of linoleic acid DMPO radical adducts exhibited the fragment ion at m/z 114 and/or the loss of neutral molecule of 113 Da (DMPO) or 131 Da (DMPO + H2O), indicated to be DMPO adducts. The short-chain products identified allowed inference of the radical oxidation along the linoleic acid chain by abstraction of hydrogen atoms in carbon atoms ranging from C-8 to C-14. Other ions containing the fragment ion at m/z 114 in the LC-MS/MS spectra were attributed to DMPO adducts of unsaturated aldehydes, hydroxy-aldehydes and oxocarboxylic acids. The identification of aldehydic products formed by radical oxidation of linoleic acid peroxidation products, as short-chain product DMPO adducts, is a means of identifying lipid peroxidation products.
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Affiliation(s)
- A Reis
- Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
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17
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Wentzel P, Ejdesjö A, Eriksson UJ. Maternal diabetes in vivo and high glucose in vitro diminish GAPDH activity in rat embryos. Diabetes 2003; 52:1222-8. [PMID: 12716756 DOI: 10.2337/diabetes.52.5.1222] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The aim of the present study was to investigate whether diabetic embryopathy may be associated with the inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) resulting from an excess of reactive oxygen species (ROS) in the embryo. Recent demonstrations of enhanced ROS production in mitochondria of bovine aortic endothelial cells exposed to high glucose have supported the idea that the pathogenesis of diabetic complications may involve ROS-induced GAPDH inhibition. We investigated whether a teratogenic diabetic environment also inhibits embryonic GAPDH activity and alters GAPDH gene expression and whether antioxidants diminish such GAPDH inhibition. In addition, we determined whether the inhibition of GAPDH with iodoacetate induces dysmorphogenesis, analogous to that caused by high glucose concentration, and whether antioxidants modulated the putative teratogenic effect of such direct GAPDH inhibition. We found that embryos from diabetic rats and embryos cultured in high glucose concentrations showed decreased activity of GAPDH (by 40-60%) and severe dysmorphogenesis on gestational days 10.5 and 11.5. GAPDH mRNA was decreased in embryos of diabetic rats compared to control embryos. Supplementing the high-glucose culture with the antioxidant N-acetylcysteine (NAC) increased GAPDH activity and diminished embryonic dysmorphogenesis. Embryos cultured with iodoacetate showed both decreased GAPDH activity and dysmorphogenesis; supplementing the culture with NAC increased both parameters toward normal values. In conclusion, dysmorphogenesis caused by maternal diabetes is correlated with ROS-induced inhibition of GAPDH in embryos, which could indicate that inhibition of GAPDH plays a causal role in diabetic embryopathy.
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Affiliation(s)
- Parri Wentzel
- Department of Medical Cell Biology, Biomedical Center, Uppsala University, PO Box 571, SE-751 23 Uppsala, Sweden.
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18
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Beisswenger PJ, Howell SK, Smith K, Szwergold BS. Glyceraldehyde-3-phosphate dehydrogenase activity as an independent modifier of methylglyoxal levels in diabetes. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1637:98-106. [PMID: 12527413 DOI: 10.1016/s09254439(02)00219-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Methylglyoxal (MG) may be an important cause of diabetic complications. Its primary source is dihydroxyacetone phosphate (DHAP) whose levels are partially controlled by glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Using a human red blood cell (RBC) culture, we examined the effect of modifying GAPDH activity on MG production. With the inhibitor koningic acid (KA), we showed a linear, concentration-dependent GAPDH inhibition, with 5 microM KA leading to a 79% reduction of GAPDH activity and a sixfold increase in MG. Changes in redox state produced by elevated pH also resulted in a 2.4-fold increase in MG production at pH 7.5 and a 13.4-fold increase at pH 7.8. We found substantial inter-individual variation in DHAP and MG levels and an inverse relationship between GAPDH activity and MG production (R=0.57, P=0.005) in type 2 diabetes. A similar relationship between GAPDH activity and MG was observed in vivo in type 1 diabetes (R=0.29, P=0.0018). Widely varying rates of progression of diabetic complications are seen among individuals. We postulate that modification of GAPDH by environmental factors or genetic dysregulation and the resultant differences in MG production could at least partially account for this observation.
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Affiliation(s)
- Paul J Beisswenger
- Department of Medicine, Endocrine-Metabolism Division, Dartmouth Medical School, Hanover, NH 03755, USA.
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19
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Schmuck G, Freyberger A, Ahr HJ, Stahl B, Kayser M. Effects of the new herbicide fentrazamide on the glucose utilization in neurons and erythrocytes in vitro. Neurotoxicology 2003; 24:55-64. [PMID: 12564382 DOI: 10.1016/s0161-813x(02)00096-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Treatment of rats with fentrazamide for 2 years at 3000 ppm (males) and 4000 ppm (females) led to an increased incidence and degree of axonal degeneration in sciatic nerve as well as to effects on red blood cells. The mechanism underlying these effects was investigated in vitro using various cell cultures (permanent rodent cell lines from the nervous system, liver, kidney, skeletal and heart muscle and fibroblasts, primary cortical neurons and erythrocytes from the rat). Added to cultured rat cortical neurons for 1 week, fentrazamide considerably decreased glucose consumption, ATP levels and mitochondrial membrane potential and lowered the GSH level, however, it had little impact on viability and neurofilaments and did not induce oxidative stress (ROS) over the first 2 h. After recovery for 1 week, in addition some destruction of neurofilaments had occurred probably secondary to the disturbance of energy production. These effects were prevented by pyruvate. Further studies indicated that fentrazamide primarily inhibited glucose utilization, most likely by interfering with glycolysis. Similar effects were found in erythrocytes treated with fentrazamide over a period of 7 days. Primarily, the glucose consumption was reduced after 1-day treatment, followed by a marked reduction of the energy supply at days 3 and 7. Comparable to the neurons, the GSH level was significantly reduced. A marked hemolysis of the red blood cells was then observed after prolonged treatment. The extensive energy demand and exclusive dependency on glucose utilization of neurons and erythrocytes may explain the specific vulnerability of motor neurons and erythrocytes. When comparing the concentrations necessary for inducing effects in vitro on neuronal cells and erythrocytes to the very low plasma concentrations of fentrazamide in treated rats it is suggested that only a small impact of fentrazamide on the energy status at high doses will occur in vivo. Therefore, aging of the rat as another factor compromising mitochondrial energy production in motor neurons must be considered as additional contribution for the induction of axonal degeneration. It is concluded that this effect of fentrazamide in rats poses no specific risk under the exposure conditions relevant to humans.
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Affiliation(s)
- Gabriele Schmuck
- BAYER AG, PH PD Toxicology, Aprather Weg 18a, D-42096 Wuppertal, Germany.
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Kim SS, Gallaher DD, Csallany AS. Vitamin E and probucol reduce urinary lipophilic aldehydes and renal enlargement in streptozotocin-induced diabetic rats. Lipids 2000; 35:1225-37. [PMID: 11132182 DOI: 10.1007/s11745-000-0639-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diabetes mellitus is characterized by complications affecting several organs, including the kidney. Lipid peroxidation increases in diabetes and has been implicated in the pathogenesis of diabetic complications. In this study, we examined the ability of two antioxidants, vitamin E and probucol, to reduce lipid peroxidation in vivo and renal hypertrophy, an early stage of diabetic nephropathy, in rats. Animals were divided into four groups: non-diabetic, diabetic, diabetic treated with vitamin E, and diabetic treated with probucol. Animals were given antioxidants by intraperitoneal injection after induction of diabetes by streptozotocin injection. After 7 wk, lipid peroxidation in vivo was measured by analyzing urinary excretion of lipophilic aldehydes and related carbonyl compounds (LACC) as 2,4-dinitrophenylhydrazones by high-performance liquid chromatography. A number of urinary lipophilic nonpolar and polar aldehydes and related carbonyl compounds were identified, almost all of which increased in diabetes. Antioxidant treatment resulted in significantly decreased excretion of urinary LACC excretion. Antioxidant treatment of diabetic rats reduced renal hypertrophy. There was a high correlation between kidney weight and urinary LACC. Since LACC are accepted markers of lipid peroxidation, these results indicate that antioxidants can reduce the elevated lipid peroxidation of diabetes and may slow the onset of diabetic nephropathy.
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Affiliation(s)
- S S Kim
- Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108, USA
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21
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Ganea E, Harding JJ. alpha-crystallin protects glucose 6-phosphate dehydrogenase against inactivation by malondialdehyde. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1500:49-58. [PMID: 10564717 DOI: 10.1016/s0925-4439(99)00087-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The present work investigates the effect of malondialdehyde (MDA) binding on the enzymic activity and on some structural properties of glucose 6-phosphate dehydrogenase (G6PD). We studied whether alpha-crystallin could protect the enzyme against MDA damage, and if so, by what mechanism. We also studied whether alpha-crystallin could renature G6PD denatured by MDA. alpha-Crystallin was prepared from bovine lenses by gel chromatography. MDA was freshly prepared and incubated with G6PD with or without alpha-crystallin. The results show that MDA reacted with G6PD non-enzymically causing inactivation at concentrations lower than those used previously on structural proteins. The modified enzyme became fluorescent. alpha-Crystallin, acting as a molecular chaperone, specifically protected the enzyme against inactivation by MDA. The enzyme was not reactivated by alpha-crystallin, but it was stabilised and protected against further denaturation. Complex formation between alpha-crystallin and the modified enzyme was demonstrated by immunoprecipitation. G6PD was very susceptible to MDA and we have shown for the first time that alpha-crystallin is able to protect the enzyme against this damage.
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Affiliation(s)
- E Ganea
- Nuffield Laboratory of Ophthalmology, University of Oxford, Walton Street, Oxford, UK
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22
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Baker AG, Wiesler D, Novotny MV. Tandem mass spectrometry of model peptides modified with trans-2-hexenal, a product of lipid peroxidation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1999; 10:613-624. [PMID: 10384725 DOI: 10.1016/s1044-0305(99)00029-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Small molecules formed during lipid peroxidation can react with the basic groups in proteins through different mechanisms. Recently, substituted pyridinium moieties were observed during in vitro incubations of lysine-containing peptides with 2-alkenals. To explore the dissociation behavior of peptides with pyridinium-derivatized lysine residues, the peptide ions created through either matrix-assisted laser desorption/ionization or electrospray ionization were studied with tandem mass spectrometry. The permanently charged pyridinium ions fragment primarily through the charge-remote processes. Under high energy collision-induced dissociation, a number of diagnostic ions were observed that could potentially be used to identify modified residues in proteins. The origins of these ions were studied using deuterium exchange and higher-order mass spectrometry experiments using an ion trap instrument. Rational structures for these ions are proposed.
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Affiliation(s)
- A G Baker
- Department of Chemistry, Indiana University, Bloomington 47405, USA
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23
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Kim SS, Gallaher DD, Csallany AS. Lipophilic aldehydes and related carbonyl compounds in rat and human urine. Lipids 1999; 34:489-96. [PMID: 10380121 DOI: 10.1007/s11745-999-0389-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Rat and human urine samples were analyzed for lipophilic aldehydes and other carbonyl products of lipid peroxidation. The following compounds were identified as their 2,4-dinitrophenyl hydrazones by cochromatography with pure standards using three solvent systems: butanal, butan-2-one, pentan-2-one, hex-2-enal, hexanal, hepta-2,4-dienal, hept-2-enal, octanal, non-2-enal, deca-2,4-dienal, 4-hydroxyhex-2-enal, and 4-hydroxynon-2-enal. In general, fasted rats excreted less of these compounds than fed rats, indicating they were partially of dietary origin or that the endogenous compounds were excreted in a form not susceptible to hydrazone formation. The compounds excreted in human urine were similar to those excreted in rat urine but were present in lower concentrations. Identification of the conjugated forms of the lipophilic aldehydes and related carbonyl compounds excreted in urine may be a source of information about their reactions in vivo.
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Affiliation(s)
- S S Kim
- Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108, USA
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24
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Kanazawa K, Ashida H. Dietary hydroperoxides of linoleic acid decompose to aldehydes in stomach before being absorbed into the body. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1393:349-61. [PMID: 9748650 DOI: 10.1016/s0005-2760(98)00089-7] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Our previous study (Biochim. Biophys. Acta 1393 (1998) 336-348, this issue) found that dietary hydroperoxides of trilinoleoylglycerol were broken down, releasing linoleic acid hydroperoxides (LA-OOH) in the stomach without reaching the intestines. The present paper describes the catabolic fate of LA-OOH in rat gastrointestines, in an attempt to elucidate those products which can be absorbed into the body. At an intragastric dose of 6.5 or 18 mumol, LA-OOH was not transported to the intestines as determined by HPLC. At large doses (200 or 800 mumol), much greater than that in the daily diet, there was partial leakage of LA-OOH to the intestines. The periodical fate was analyzed with 17.2 mumol [U-14C]LA-OOH chemically and radiochemically. Exemplifying the product composition at 30 min after treatment (as percentage of dosed amount), 27% unchanged LA-OOH, 9.7% epoxyketones, 3.5% hydroxyls (LA-OH), 2.4% decomposed aldehydes, and 13% unknown products were found in the gastric lumen. Another 25% was incorporated in the gastric tissue, and the other 6.4% occurred in the intestinal lumen and tissue as decomposed aldehyde. The LA-OH further decomposed to aldehydes with time in the stomach. When an aldehyde mixture was prepared and dosed, significant increases in hexanal and 4-hydroxynonenal were detected in the liver 15 h later. These results show that the dietary LA-OOH is decomposed to aldehydes in the stomach and that aldehydes are partly absorbed into the body.
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Affiliation(s)
- K Kanazawa
- Laboratory of Food and Nutritional Chemistry, Faculty of Agriculture, Kobe University, Japan.
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Kanazawa K, Ashida H. Catabolic fate of dietary trilinoleoylglycerol hydroperoxides in rat gastrointestines. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1393:336-48. [PMID: 9748647 DOI: 10.1016/s0005-2760(98)00088-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To elucidate whether dietary lipid peroxides are absorbed in the body, the catabolic fate of trilinoleoylglycerol hydroperoxides (TL-OOH), in the gastrointestines of rats was examined. Oxidized trilinoleoylglycerol with a peroxide value of 1000 meq/kg, 0.5 or 20 mg, was dosed intragastrically to rat together with 59.5 or 40 mg unoxidized trilinoleoylglycerol, respectively. The fate of TL-OOH in gastric and intestinal lumina was determined by high-performance liquid chromatography periodically until 240 min after treatment. At low dose, TL-OOH was soon broken down to linoleic acid hydroperoxides (LA-OOH) and hydroxyls, probably through gastric lipases, whereas at high dose, TL-OOH was retained in the stomach. In both cases, TL-OOH did not reach the intestines, though the unoxidized lipids moved to the intestines. When LA-OOH was given intragastrically, the lipids decomposed in the stomach, and linoleic acid hydroxyls, hexanal, 9-oxononanoic acid, and two novel compounds were detected 30 min after treatment. The novel compounds were identified to be epoxyketones, 11-oxo-12,13-epoxy-9- and 11-oxo-9,10-epoxy-12-octadecenoic acids. Thus, dietary TL-OOH was broken down in the stomach releasing, LA-OOH which decomposed further, and did not reach the intestines.
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Affiliation(s)
- K Kanazawa
- Laboratory of Food and Nutritional Chemistry, Faculty of Agriculture, Kobe University, Japan.
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Trueblood N, Ramasamy R. Aldose reductase inhibition improves altered glucose metabolism of isolated diabetic rat hearts. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H75-83. [PMID: 9688898 DOI: 10.1152/ajpheart.1998.275.1.h75] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alterations in glucose metabolism have been implicated in the cardiovascular complications of diabetes. Previous work in this laboratory demonstrated that hearts from diabetic animals have an elevated cytosolic redox ratio (NADH/NAD+) and that this redox imbalance is probably due to elevated polyol pathway flux. We therefore hypothesized that 1) the elevated cytosolic redox ratio of diabetic hearts could result in inhibition of glycolytic enzymes sensitive to the redox state, 2) polyol pathway inhibition could restore the abnormal glucose metabolism of diabetic hearts, and 3) the relative incorporation of mixed substrates into hearts from diabetic animals would demonstrate less glycolytic and more fatty acid oxidation. Hearts from diabetic (BB/W) and nondiabetic control rats were perfused with buffers containing 13C-labeled substrates, and the metabolism of these hearts was analyzed using 13C NMR spectroscopy. Tissue samples were analyzed for metabolite levels using biochemical assay. Compared with controls, diabetic hearts had glyceraldeyde 3-phosphate levels that were four times greater than nondiabetic hearts and exhibited 91% less 13C labeling of lactate and 92% less 13C labeling of glutamate (P < 0.03). Aldose reductase inhibition with zopolrestat restored the metabolite labeling of diabetic hearts. Diabetic hearts perfused with a mixture of substrates used 53% more acetate than nondiabetic control hearts (P < 0.05), and aldose reductase inhibition lowered the acetate utilization of diabetic hearts by 9% (P < 0.05). These data suggest that glycolytic flux in diabetic hearts is inhibited at glyceraldehyde-3-phosphate dehydrogenase and that inhibition of the polyol pathway with zopolrestat increases glycolytic flux in these hearts. Furthermore, hearts from diabetic animals showed a marked dependence on fatty acids for substrate utilization compared with nondiabetic controls, consistent with inhibition of the pyruvate dehydrogenase complex in diabetic hearts.
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Affiliation(s)
- N Trueblood
- Division of Cardiovascular Medicine, University of California, Davis, California 95616, USA
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Abstract
Coronary heart disease (CHD) is pathogenetically linked to numerous metabolic disturbances. These are inextricably interrelated, constituting identifiable clusters or syndromes of cardiovascular risk. Prominent among these is the insulin resistance syndrome, whose components, including hyperuricemia, have all been linked to CHD pathogenesis. Many mechanisms have been put forward to account for the emergence of this syndrome, but none offer a satisfactory explanation for the involvement of hyperuricemia. Possible explanations relate to the observation of glycolytic disturbances in insulin-resistant and hyperuricemic states. This might be expected from the fact that uric acid production is linked to glycolysis and that glycolysis is controlled by insulin. Phosphoribosylpyrophosphate (PPRP) is an important metabolite in this respect. Its availability depends on ribose-5-phosphate (R-5-P), the production of which is governed by glycolytic flux. Diversion of glycolytic intermediates toward R-5-P, PPRP, and uric acid will follow if there is diminished activity of glyceraldehyde-3-phosphate dehydrogenase (GA3PDH), which is regulated by insulin. Serum triglyceride concentrations may also increase, as might be expected from accumulation of glycerol-3-phosphate. Thus, intrinsic defects in GA3PDH and a loss of its responsiveness to insulin, by causing accumulation of glycolytic intermediates, may explain the association between insulin resistance, hyperuricemia, and hypertriglyceridemia. This scenario raises the possibility that disturbances of a single glycolytic enzyme may be pivotal in the modulation of metabolic risk factors for CHD.
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Affiliation(s)
- F Leyva
- Wynn Department of Metabolic Medicine, Imperial College School of Medicine, London, UK
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Endogenous monocarboxylates sustain hippocampal synaptic function and morphological integrity during energy deprivation. J Neurosci 1998. [PMID: 9391000 DOI: 10.1523/jneurosci.17-24-09448.1997] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ability to fuel neurons via glycogenolysis is believed to be an important function of glia. Indeed, the slow, rather than immediate, depression of synaptic transmission in hippocampal slices during exogenous glucose deprivation suggests that intrinsic energy reservoirs help to sustain neurotransmission. It is believed that glia fuel neighboring neurons via diffusible monocarboxylates such as pyruvate and lactate, although a role for glucose has been proposed also. Using alpha-cyano-4-hydroxycinnamate (4-CIN) to inhibit monocarboxylate transport and cytochalasin B (CCB) to inhibit glucose transport, we examined the role of glucose and monocarboxylates in supporting the functional and morphological integrity of hippocampal neurons during glucose deprivation. Although 200 microM 4-CIN failed to depress EPSPs supported by 10 mM glucose, pretreatment with 4-CIN accelerated the depression of EPSPs during glucose deprivation. 4-CIN also accelerated the decline in glucose-supported EPSPs after administration of 50 microM CCB, whereas CCB failed to alter the slow decay of pyruvate-supported EPSPs during pyruvate deprivation. 4-CIN did not alter the morphology of pyramidal neurons in the presence of 10 mM glucose but produced significant damage during glucose deprivation or CCB administration. These results suggest that endogenous monocarboxylates rather than glucose maintain neuronal integrity during energy deprivation. Furthermore, EPSPs supported by 2-3.3 mM glucose were sensitive to 4-CIN, suggesting that endogenous monocarboxylates are involved in maintaining neuronal function even under conditions of mild glucose deprivation.
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Abstract
4-Hydroxy-2-nonenal (HNE), one of the major products of lipid peroxidation, inactivated the rate-limiting enzymes (from animal sources) of the glycolytic pathway and the pentose phosphate pathway when incubated at 37 degrees C for 1 h in the absence of glutathione (GSH). The HNE concentration for half-maximal inactivation of 6-phosphofructokinase (PFK) and glyceraldehyde-3-phosphate dehydrogenase was 3-10 microM; and that value for pyruvate kinase, glucose-6-phosphate dehydrogenase, and hexokinases I and II was 0.15-0.6 mM. In the presence of 5 mM GSH, however, only PFK, irrespective of the source (muscle, liver, or erythrocyte), was inactivated by 40-50% when incubated with 0.1 mM HNE for 1 h. Even PFK was not inactivated in the presence of both GSH and its substrate, ATP (2 mM). Glycolysis in human erythrocytes was not affected by treatment of cells with 0.1 mM HNE at 37 degrees C for 30 min. The results suggest that HNE, at concentrations observable under physiological and pathological conditions, hardly affects glycolysis in cells.
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Affiliation(s)
- I Miwa
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Nagoya, Tempaku-ku, Japan
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