351
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Nyengaard JR, Ido Y, Kilo C, Williamson JR. Interactions between hyperglycemia and hypoxia: implications for diabetic retinopathy. Diabetes 2004; 53:2931-8. [PMID: 15504974 DOI: 10.2337/diabetes.53.11.2931] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The primary aim of these experiments was to assess in vitro effects of hyperglycemia (30 mmol/l glucose) and hypoxia (Po(2) = 36 torr) of 2-h duration, separately and in combination, on cytosolic and mitochondrial free NADH (NADHc and NADHm, respectively) in retinas from normal rats. NADH is the major carrier of electrons and protons that fuel ATP synthesis and several metabolic pathways linked to diabetic complications. Hyperglycemia and hypoxia increase free NADHc by different mechanisms that are additive. Hyperglycemia increases transfer of electrons and protons from sorbitol to NAD(+)c, reducing it to NADHc, but does not increase NADHm. Hypoxia increases NADHm by inhibiting its oxidation. Electrons and protons accumulating in NADHm restrain transfer of electrons and protons from NADHc to NAD(+)m via the malate-aspartate electron shuttle. Hyperglycemia and hypoxia also increase glycolysis by different mechanisms that are additive, and hyperglycemia increases ATP levels in hypoxic and in aerobic retinas. The additive effects of hyperglycemia and hypoxia on accumulation of electrons and protons in a common pool of free NADHc confirm the test hypothesis and the potential of a combination of these two risk factors to accelerate the onset and progression of diabetic retinopathy (and other complications of diabetes) by augmenting metabolic pathways fueled by free NADHc.
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Affiliation(s)
- Jens R Nyengaard
- Stereological Research and Electron Microscopical Laboratory, University of Aarhus, Denmark.
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352
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Di Loreto S, Caracciolo V, Colafarina S, Sebastiani P, Gasbarri A, Amicarelli F. Methylglyoxal induces oxidative stress-dependent cell injury and up-regulation of interleukin-1β and nerve growth factor in cultured hippocampal neuronal cells. Brain Res 2004; 1006:157-67. [PMID: 15051519 DOI: 10.1016/j.brainres.2004.01.066] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2004] [Indexed: 11/29/2022]
Abstract
Methylglyoxal (MG) is one of the most powerful glycating agents of proteins and other important cellular components and has been shown to be toxic to cultured cells. Under hyperglycaemic conditions, an increase in the concentration of MG has been observed in human body fluids and tissues that seems to be responsible for diabetic complications. Recent data suggest that diabetes may cause impairment of cognitive processes, according to a mechanism involving both oxidative stress and advanced glycation end product (AGE) formation. In this work, we explored the molecular mechanism underlying MG toxicity in neural cells, by investigating the effect of MG on both the interleukin-1beta (IL-1beta), as the major inducer of the acute phase response, and the nervous growth factor (NGF) expression. Experiments were performed on cultured neural cells from rat hippocampus, being this brain region mostly involved in cognitive processes and, therefore, possible target of diabetes-mediated impairment of cognitive abilities. Results show that MG treatment causes in hippocampal neural cells extensive, oxidative stress-mediated cell death, in consequence of a strong catalase enzymatic activity and protein inhibition. MG also causes a very significant increase in both transcript and protein expression of the NGF as well as of the pro-inflammatory cytokine IL-1beta. MG co-treatment with the antioxidant N-acetylcysteine (NAC) completely abrogates the observed effects. Taken together, these data demonstrate that hippocampal neurons are strongly susceptible to MG-mediated oxidative stress.
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Affiliation(s)
- Silvia Di Loreto
- Institute of Organ Transplants and Immunocytology, CNR, L'Aquila, Italy
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353
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Irsch T, Krauth-Siegel RL. Glyoxalase II of African Trypanosomes Is Trypanothione-dependent. J Biol Chem 2004; 279:22209-17. [PMID: 14976196 DOI: 10.1074/jbc.m401240200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glyoxalase system is a ubiquitous pathway catalyzing the glutathione-dependent detoxication of ketoaldehydes such as methylglyoxal, which is mainly formed as a by-product of glycolysis. The gene encoding a glyoxalase II has been cloned from Trypanosoma brucei, the causative agent of African sleeping sickness. The deduced protein sequence contains the highly conserved metal binding motif THXHXDH but lacks three basic residues shown to fix the glutathione-thioester substrate in the crystal structure of human glyoxalase II. Recombinant T. brucei glyoxalase II hydrolyzes lactoylglutathione, but does not show saturation kinetics up to 5 mm with the classical substrate of glyoxalases II. Instead, the parasite enzyme strongly prefers thioesters of trypanothione (bis(glutathionyl)spermidine), which were prepared from methylglyoxal and trypanothione and analyzed by high performance liquid chromatography and mass spectrometry. Mono-(lactoyl)trypanothione and bis-(lactoyl)trypanothione are hydrolyzed by T. brucei glyoxalase II with k(cat)/K(m) values of 5 x 10(5) m(-1) s(-1) and 7 x 10(5) m(-1) s(-1), respectively, yielding d-lactate and regenerating trypanothione. Glyoxalase II occurs in the mammalian bloodstream and insect procyclic form of T. brucei and is the first glyoxalase II of the order of Kinetoplastida characterized so far. Our results show that the glyoxalase system is another pathway in which the nearly ubiquitous glutathione is replaced by the unique trypanothione in trypanosomatids.
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Affiliation(s)
- Thorsten Irsch
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
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354
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Aguilera J, Prieto JA. Yeast cells display a regulatory mechanism in response to methylglyoxal. FEMS Yeast Res 2004; 4:633-41. [PMID: 15040952 DOI: 10.1016/j.femsyr.2003.12.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Revised: 12/12/2003] [Accepted: 12/12/2003] [Indexed: 12/31/2022] Open
Abstract
Methylglyoxal (MG), a glycolytic by-product, is an extremely toxic compound. This fact suggests that its synthesis and degradation should be tightly controlled. However, little is known about the mechanisms that protect yeast cells against MG toxicity. Here, we show that in Saccharomyces cerevisiae, MG exposure increased the internal MG content and activated the expression of GLO1 and GRE3, two genes involved in MG detoxification; GPD1, the gene for glycerol synthesis; and TPS1 and TPS2, the trehalose pathway genes. This response was specific as demonstrated by the analysis of marker genes and effectors of the general stress response. Physiological experiments with MG-treated cells showed that this compound triggers the overproduction of glycerol. Furthermore, a gpd1 gpd2 double mutant showed enhanced MG contents compared with the wild-type. Overall, these results appeared to indicate that up-variations in the intracellular content of the toxic compound are perceived by the cell as a primary signal to trigger the transcriptional response. In agreement with this, MG-instigated GPD1 activation was enhanced in strains lacking GLO1, and this effect correlated with the internal MG content. Finally, induction of GPD1, TPS1 and GRE3, and enhanced MG contents were also observed in low-glucose-growing cells subjected to a sudden increase in glucose availability. The implications of this regulatory mechanism on protection against MG are discussed.
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Affiliation(s)
- Jaime Aguilera
- Department of Biotechnology, Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas, Poligono de la Coma, s/n, P.O. Box 73, Burjassot Valencia 46100, Spain
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355
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Abstract
A number of aldose reductase inhibitors (ARIs) have been developed over the past few decades with the expectation of therapeutic effects for diabetic complications. Neuropathy is the complication that has been most intensively studied as a potential target for ARIs. Most ARIs have shown satisfactory effects in animal models. However, the clinical potential of ARIs in diabetic patients has been controversial due to the lack of conclusive evidence. The safety of this category of drugs is also uncertain. This article summarizes the results of clinical trials of ARIs for patients with diabetic neuropathy that have been performed to date. The efficacy and toxicity of each ARI will be briefly assessed by the clinical data. The theoretical background along with major issues in the evaluation of drug efficacy will also be discussed. Overall the observed efficacy varied among the compounds. A few ARIs showed favorable effects in multiple endpoints in the majority of trials, while the results from many ARIs seemed ambivalent. One drug barely exhibited positive effects on any endpoint. This discrepancy may be attributable at least in part to the different degree of inhibition of the polyol pathway in nerve tissues, which is determined not only by the pharmacokinetic properties of the drug but also by its penetration into nerve tissues. In addition to the uncertain potential of each ARI, the issues of design and analytical methods used for clinical trials may underlie the ambivalent outcomes. The power of analysis and the duration of trials were apparently inadequate in a large number of the studies. Various indices selected as endpoints are not necessarily sensitive or reproducible. Studies of longer duration, large-scale trials, better methods to assess neuropathy, and the selection of patients with a homogenous background would provide more conclusive evidence. The risk of serious adverse reactions, for example, hypersensitivity reactions and hepatic damage, has led to some ARIs being withdrawn from the market or from further development. These adverse effects, however, do not appear to result from the inhibition of aldose reductase activity per se but from specific reactions to each compound. In conclusion, sufficient inhibition of the nerve aldose reductase activity seems likely to prevent or ameliorate diabetic neuropathy, and further development of more potent and safe ARIs is necessary before extensive clinical application.
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Affiliation(s)
- Yoji Hamada
- Division of Metabolic Diseases, Nagoya University Graduate School of Medicine, Nagoya, Japan.
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356
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Beisswenger P, Ruggiero-Lopez D. Metformin inhibition of glycation processes. DIABETES & METABOLISM 2003; 29:6S95-103. [PMID: 14502106 DOI: 10.1016/s1262-3636(03)72793-1] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A number of studies have shown that metformin is beneficial in reducing diabetes associated vascular risk beyond the benefits expected from its antihyperglycaemic effect. One of the main pathogenic mechanisms leading to chronic complications of diabetes is non-enzymatic glycation where damage is mediated through increased production of highly chemically reactive glucose and alpha-dicarbonyl compounds which lead to production of advanced glycation products (AGEs). We present laboratory and clinical data supporting the hypothesis that one important explanation of metformin's effect on diabetic complications could be its ability to reduce toxic dicarbonyls and AGEs. This effect could be related either to the binding of the alpha-dicarbonyls, methylglyoxal (MG) or 3-deoxyglucosone, or to an increase in enzymatic detoxification. Our studies presented in this manuscript document extracellular binding of MG by metformin to form a specific product (triazepinone) in vivo. This condensation product appears to be only one of several inactive end products resulting from this chemical reaction and we discuss the possibility that these or other condensation products (hydroimidazolones) could be indicative of inactivation of MG by metformin. Additional studies of other possible condensation products, as well as other potential cellular effects of metformin on MG production, will help to clarify this potentially important effect of metformin and provide a further rationale for using metformin to prevent long-term complications.
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357
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Abstract
Methylglyoxal is an endogenous metabolic by-product of glycolysis and has genotoxic effects. Previous studies suggested that the reaction of methylglyoxal with amino acid leads to the production of free radicals. In this study, oxidative damage of DNA by the reaction of methylglyoxal with amino acid was investigated. When plasmid DNA was incubated with methylglyoxal and lysine, DNA strand was cleaved. Cu(2+) enhanced DNA strand breakage induced by the reaction of methylglyoxal with lysine. The formation of superoxide anion was detected during the glycation reaction of methylglyoxal with lysine. Radical scavengers, catalase, and copper chelators inhibited the DNA breakage. The deoxyribose assay showed that hydroxyl radicals were generated during the reaction of methylglyoxal with lysine in the presence of Cu(2+). The generation of hydroxyl radicals was inhibited by radical scavenger, catalase, and copper chelator. These results suggest that superoxide anion and H2O2 may generate from the glycation reaction of methylglyoxal with lysine and then Cu(2+) likely participates in a Fenton's type reaction to produce hydroxyl radicals, which may cause DNA cleavage. This mechanism may be linked to several diverse biological processes including mutagenesis, aging, carcinogenesis, and diabetic complications.
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Affiliation(s)
- Jung Hoon Kang
- Department of Genetic Engineering, Chongju University, Chongju 360-764, South Korea.
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358
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Amicarelli F, Colafarina S, Cattani F, Cimini A, Di Ilio C, Ceru MP, Miranda M. Scavenging system efficiency is crucial for cell resistance to ROS-mediated methylglyoxal injury. Free Radic Biol Med 2003; 35:856-71. [PMID: 14556850 DOI: 10.1016/s0891-5849(03)00438-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Methylglyoxal is a reactive dicarbonyl compound endogenously produced mainly from glycolytic intermediates. Recent research indicates that methylglyoxal is a potent growth inhibitor and genotoxic agent. The antiproliferative activity of methylglyoxal has been investigated for pharmacological application in cancer chemotherapy. However, various cells are not equally sensitive to methylglyoxal toxicity. Therefore, it would be important to establish the cellular factors responsible for the different cell-type specific response to methylglyoxal injury, in order to avoid the risk of failure of a therapy based on increasing the intracellular level of methylglyoxal. To this purpose, we comparatively evaluated the signaling transduction pathway elicited by methylglyoxal in human glioblastoma (ADF) and neuroblastoma (SH-SY 5Y) cells. Results show that methylglyoxal causes early and extensive reactive oxygen species generation in both cell lines. However, SH-SY 5Y cells show higher sensitivity to methylglyoxal challenge due to a defective antioxidant and detoxifying ability that, preventing these cells from an efficient scavenging action, elicits extensive caspase-9 dependent apoptosis. These data emphasize the pivotal role of antioxidant and detoxifying systems in determining the grade of sensitivity of cells to methylglyoxal.
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Affiliation(s)
- Fernanda Amicarelli
- Department of Basic and Applied Biology, Faculty of Science, L'Aquila University, L'Aquila, Italy.
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359
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Ahmed N, Battah S, Karachalias N, Babaei-Jadidi R, Horányi M, Baróti K, Hollan S, Thornalley PJ. Increased formation of methylglyoxal and protein glycation, oxidation and nitrosation in triosephosphate isomerase deficiency. Biochim Biophys Acta Mol Basis Dis 2003; 1639:121-32. [PMID: 14559119 DOI: 10.1016/j.bbadis.2003.08.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Triosephosphate isomerase deficiency is associated with the accumulation of dihydroxyacetonephosphate (DHAP) to abnormally high levels, congenital haemolytic anaemia and a clinical syndrome of progressive neuromuscular degeneration leading to infant mortality. DHAP degrades spontaneously to methylglyoxal (MG)--a potent precursor of advanced glycation endproducts (AGEs). MG is detoxified to D-lactate intracellularly by the glyoxalase system. We investigated the changes in MG metabolism and markers of protein glycation, oxidation and nitrosation in a Hungarian family with two germline identical brothers, compound heterozygotes for triosephosphate isomerase deficiency, one with clinical manifestations of chronic neurodegeneration and the other neurologically intact. The concentration of MG and activity of glyoxalase I in red blood cells (RBCs) were increased, and the concentrations of D-lactate in blood plasma and D-lactate urinary excretion were also increased markedly in the propositus. There were concomitant increases in MG-derived AGEs and the oxidative marker dityrosine in hemoglobin. Smaller and nonsignificant increases were found in the neurologically unaffected brother and parents. There was a marked increase (15-fold) in urinary excretion of the nitrosative stress marker 3-nitrotyrosine in the propositus. The increased derangement of MG metabolism and associated glycation, oxidative and nitrosative stress in the propositus may be linked to neurodegenerative process in triosephosphate isomerase deficiency.
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Affiliation(s)
- Naila Ahmed
- Department of Biological Sciences, University of Essex, Central Campus, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
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360
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Hauck T, Hübner Y, Brühlmann F, Schwab W. Alternative pathway for the formation of 4,5-dihydroxy-2,3-pentanedione, the proposed precursor of 4-hydroxy-5-methyl-3(2H)-furanone as well as autoinducer-2, and its detection as natural constituent of tomato fruit. Biochim Biophys Acta Gen Subj 2003; 1623:109-19. [PMID: 14572908 DOI: 10.1016/j.bbagen.2003.08.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The formation of 4-hydroxy-5-methyl-3(2H)-furanone (HMF, norfuraneol) by spinach ribosephosphate isomerase was reinvestigated. Incubation experiments using D-ribose-5-phosphate and D-ribulose-5-phosphate clearly revealed a spontaneous nonenzymatic formation of the hydroxy-furanone from the ketose-phosphate under physiological conditions at 35 degrees C and pH 7.5, whereupon up to 1.3% of D-ribulose-5-phosphate was transformed to HMF within 15 h. 4,5-Dihydroxy-2,3-pentanedione was deduced as ultimate precursor of HMF, since addition of o-phenylenediamine to the incubation mixture led to lower amounts of HMF and to the formation of 3-(1,2-dihydroxyethyl)-2-methylquinoxaline, which was identified by means of high pressure liquid chromatography with diode array detection (HPLC-DAD), HPLC-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) and NMR spectroscopy. Additionally, the spontaneous formation of 4,5-dihydroxy-2,3-pentanedione was demontrated by its conversion to the respective alditol acetate using either NaBH(4) or NaBD(4) for the reduction. Comparative gas chromatography-mass spectrometry (GC-MS) analysis revealed the incorporation of two deuterium atoms and confirmed the dicarbonyl structure. Application of 1-13C-D-ribulose-5-phosphate as well as 5-13C-D-ribulose-5-phosphate and analysis of the derived quinoxaline derivatives by HPLC-ESI-MS/MS demonstrated the formation of the methyl-group at C-5 of the carbohydrate phosphate in consequence of a nonenzymatic phosphate elimination. Application of o-phenylenediamine into ripe tomatoes led to the detection of 3-(1,2-dihydroxyethyl)-2-methylquinoxaline by means of HPLC-MS/MS analysis implying the genuine occurrence of 4,5-dihydroxy-2,3-pentanedione in this fruit.
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Affiliation(s)
- Tobias Hauck
- Lehrstuhl für Lebensmittelchemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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361
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Abstract
The term "advanced glycation end products" (AGEs) stands for a heterogeneous group of amino acid derivatives that are formed via glycation processes between peptide-bound lysine or arginine derivatives and carbonyl compounds, processes originally known from food systems as "Maillard reactions." AGEs accumulate in plasma and tissues with advancing age, diabetes, and particular renal failure. In vivo and in vitro studies indicate that AGEs represent an important class of uremic toxins. This review focuses on the chemistry behind the formation of AGEs, possible mechanisms underlying the accumulation of AGEs in uremia, clinical and therapeutic implications, and possible nutritional consequences.
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Affiliation(s)
- Thomas Henle
- Institute of Food Chemistry, Technical University of Dresden, Germany
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362
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Speer O, Morkunaite-Haimi S, Liobikas J, Franck M, Hensbo L, Linder MD, Kinnunen PKJ, Wallimann T, Eriksson O. Rapid suppression of mitochondrial permeability transition by methylglyoxal. Role of reversible arginine modification. J Biol Chem 2003; 278:34757-63. [PMID: 12815061 DOI: 10.1074/jbc.m301990200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Methylglyoxal (MG) (pyruvaldehyde) is a reactive carbonyl compound produced in glycolysis. MG can form covalent adducts on proteins resulting in advanced glycation end products that may alter protein function. Here we report that MG covalently modifies the mitochondrial permeability transition pore (PTP), a high conductance channel involved in the signal transduction of cell death processes. Incubation of isolated mitochondria with MG for a short period of time (5 min), followed by removal of excess free MG, prevented both ganglioside GD3- and Ca2+-induced PTP opening and the ensuing membrane depolarization, swelling, and cytochrome c release. Under these conditions MG did not significantly interfere with mitochondrial substrate transport, respiration, or oxidative phosphorylation. The suppression of permeability transition was reversible following extended incubation in MG-free medium. Of the 29 physiological carbonyl and dicarbonyl compounds tested only MG and its analogue glyoxal were able to specifically alter the behavior of the PTP. Using a set of arginine-containing peptides, we found that the major MG-derived arginine adduct formed, following a short time exposure to MG, was the 5-hydro-5-methylimidazol-4-one derivative. These findings demonstrate that MG rapidly modifies the PTP covalently and stabilizes the PTP in the closed conformation. This is probably due to the formation of an imidazolone adduct on an arginine residue involved in the control of PTP conformation (Linder, M. D., Morkunaite-Haimi, S., Kinnunen, P. J. K., Bernardi, P., and Eriksson, O. (2002) J. Biol. Chem. 277, 937-942). We deduce that the permeability transition constitutes a potentially important physiological target of MG.
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Affiliation(s)
- Oliver Speer
- Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine/Biochemistry, P. O. Box 63, Haartmaninkatu 8, FIN-00014 University of Helsinki, Helsinki, Finland
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363
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Benov L, Beema AF, Sequeira F. Triosephosphates are toxic to superoxide dismutase-deficient Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1622:128-32. [PMID: 12880950 DOI: 10.1016/s0304-4165(03)00134-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Increase in the production of triosephosphates has been considered an important factor leading to diabetic complications. It might be expected that like the other short chain monosaccharides, triosephosphates autoxidize producing superoxide radical and alpha,beta-diketones. Since superoxide can also initiate the oxidation of short chain sugars, free radical chain reactions are possible. If such reactions occur in vivo, triosephosphates would be more deleterious to cells lacking superoxide dismutase (SOD) than to normal cells. Here we demonstrate that triosephosphates kill a SOD-deficient Escherichia coli mutant much more than the parental, SOD-proficient strain. The effect is oxygen-dependent and is partially suppressed by aminoguanidine. Increased production of superoxide and diketones appeared to be the cause of triosephosphates toxicity.
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Affiliation(s)
- Ludmil Benov
- Department of Biochemistry, Faculty of Medicine, Kuwait University, PO Box 24923 Safat, 13110, Kuwait.
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364
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Hauck T, Brühlmann F, Schwab W. Formation of 4-hydroxy-2,5-dimethyl-3[2H]-furanone by Zygosaccharomyces rouxii: identification of an intermediate. Appl Environ Microbiol 2003; 69:3911-8. [PMID: 12839760 PMCID: PMC165134 DOI: 10.1128/aem.69.7.3911-3918.2003] [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: 11/20/2022] Open
Abstract
The formation of the important flavor compound 4-hydroxy-2,5-dimethyl-3[2H]-furanone (HDMF; Furaneol) from D-fructose-1,6-bisphosphate by the yeast Zygosaccharomyces rouxii was studied with regard to the identification of intermediates present in the culture medium. Addition of o-phenylenediamine, a trapping reagent for alpha-dicarbonyls, to the culture medium and subsequent analysis by high-pressure liquid chromatography with diode array detection revealed the formation of three quinoxaline derivatives derived from D-fructose-1,6-bisphosphate under the applied growth conditions (30 degrees C; pH 4 to 5). Isolation and characterization of these compounds by tandem mass spectrometry and nuclear magnetic resonance spectroscopy led to the identification of phosphoric acid mono-(2,3,4-trihydroxy-4-quinoxaline-2-yl-butyl) ester (Q1), phosphoric acid mono-[2,3-dihydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q2), and phosphoric acid mono-[2-hydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q3). Q1 and Q2 were formed independently of Z. rouxii cells, whereas Q3 was detected only in incubation systems containing the yeast. Identification of Q2 demonstrated for the first time the chemical formation of 1-deoxy-2,3-hexodiulose-6-phosphate in the culture medium, a generally expected but never identified intermediate in the formation pathway of HDMF. Since HDMF was detected only in the presence of Z. rouxii cells, additional enzymatic steps were presumed. Incubation of periplasmic and cytosolic protein extracts obtained from yeast cells with D-fructose-1,6-bisphosphate led to the formation of HDMF, implying the presence of the required enzymes in both extracts.
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Affiliation(s)
- Tobias Hauck
- Lehrstuhl für Lebensmittelchemie, Universität Würzburg, 97074 Würzburg, Germany
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365
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Nagai R, Araki T, Hayashi CM, Hayase F, Horiuchi S. Identification of N epsilon-(carboxyethyl)lysine, one of the methylglyoxal-derived AGE structures, in glucose-modified protein: mechanism for protein modification by reactive aldehydes. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 788:75-84. [PMID: 12668073 DOI: 10.1016/s1570-0232(02)01019-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We have developed a separation system for N(epsilon)-(carboxyethyl)lysine (CEL) and N(epsilon)-(carboxymethyl)lysine (CML) by HPLC equipped with a styrene-divinylbenzene copolymer resin coupled with sulfonic group cation-exchange column and examined whether CEL is formed from proteins modified by glucose via the Maillard reaction. CEL was generated by incubating bovine serum albumin (BSA) with glucose, a reaction inhibited by aminoguanidine, but enhanced by phosphate. Although several aldehydes were detected during incubation of N(alpha)-acetyllysine with glucose, incubation of BSA with methylglyoxal alone generated CEL. These results indicate that methylglyoxal is responsible for CEL formation on protein in vitro.
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Affiliation(s)
- Ryoji Nagai
- Department of Biochemistry, Kumamoto University School of Medicine, Honjo 2-2-1, Japan
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366
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Hauck T, Landmann C, Brühlmann F, Schwab W. Formation of 5-methyl-4-hydroxy-3[2H]-furanone in cytosolic extracts obtained from Zygosaccharomyces rouxii. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2003; 51:1410-1414. [PMID: 12590490 DOI: 10.1021/jf025948m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Formation of the flavor compound and precursor 4-hydroxy-5-methyl-3[2H]-furanone (HMF, norfuraneol) was demonstrated in cytosolic protein extracts obtained from Zygosaccharomyces rouxii after incubation with a number of carbohydrate phosphates. 4-Hydroxy-5-methyl-3[2H]-furanone was produced from d-fructose-1,6-diphosphate, d-fructose-6-phosphate, d-glucose-6-phosphate, 6-phosphogluconate, d-ribose-5-phosphate, and d-ribulose-1,5-diphosphate. Enzyme assays revealed d-fructose-1,6-diphosphatase, phosphohexose isomerase, d-glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase activity in the cytosolic extracts. Model studies showed the spontaneous formation of HMF from d-ribulose-5-phosphate. It is assumed that d-ribulose-5-phosphate is generated in cytosolic extracts by the action of the investigated enzymes from the carbohydrate phosphates and is then chemically transformed to HMF. The hypothesis was proven by the production of HMF in solutions containing commercially available enzymes and [6-(13)C]-d-glucose-6-phosphate.
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Affiliation(s)
- Tobias Hauck
- Lehrstuhl für Lebensmittelchemie, Universität Würzburg, Am Hubland, Germany
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367
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Kilhovd BK, Giardino I, Torjesen PA, Birkeland KI, Berg TJ, Thornalley PJ, Brownlee M, Hanssen KF. Increased serum levels of the specific AGE-compound methylglyoxal-derived hydroimidazolone in patients with type 2 diabetes. Metabolism 2003; 52:163-7. [PMID: 12601626 DOI: 10.1053/meta.2003.50035] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A time-delayed fluorescence immunoassay was developed for the determination of serum levels of methylglyoxal (MG)-derived hydroimidazolone using a monoclonal antiserum raised against Nalpha-acetyl-Ndelta-(5-hydro-5-methyl)-4-imidazolone, Europium-labeled anti-mouse IgG antiserum as indicator, and MG modified bovine serum albumin (BSA) as standard. Serum levels of hydroimidazolone were measured in 45 patients with type 2 diabetes aged 59.4 +/- 6.1 (mean +/- SD) years and with duration of diabetes of 7.3 +/- 3.1 years, and in 19 nondiabetic controls aged 56.3 +/- 4.3 years. The serum levels of hydroimidazolone were significantly higher in patients compared to controls: median, 3.0 (5-95 percentile, 1.6 to 5.4) U/mg protein versus 1.9 (1.2 to 2.8) U/mg protein (P =.0005). Significant positive correlations were observed between the serum levels of hydroimidazolone and serum levels of advanced glycation end products (AGEs), measured with a polyclonal anti-AGE antibody: r = 0.59 for patients (P <.0001), and r = 0.65 for controls (P =.002). Similarly, significant correlations were also found between serum levels of hydroimidazolone and N(epsilon)-(carboxymethyl)-lysine (CML): r = 0.36 in patients and r = 0.55 for controls (both P =.02). Serum hydroimidazolone levels did not correlate with fasting plasma glucose or hemoglobin A(1c) (HbA(1c)) levels. The observed differences between patients with diabetes and nondiabetic controls seem to be comparable to differences measured for other AGE compounds.
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Affiliation(s)
- B K Kilhovd
- Aker Diabetes Research Centre and the Hormone Laboratory, Aker University Hospital, Oslo, Norway
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368
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Thornalley PJ. Glycation in diabetic neuropathy: characteristics, consequences, causes, and therapeutic options. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 50:37-57. [PMID: 12198817 DOI: 10.1016/s0074-7742(02)50072-6] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glycation is the nonenzymatic reaction of glucose, alpha-oxoaldehydes, and other saccharide derivatives with proteins, nucleotides, and lipids. Early glycation adducts (fructosamines) and advanced glycation adducts (AGEs) are formed. "Glycoxidation" is a term used for glycation processes involving oxidation. Sural, peroneal, and saphenous nerves of human diabetic subjects contained AGEs in the perineurium, endothelial cells, and pericytes of endoneurial microvessels and in myelinated and unmyelinated fibres localized to irregular aggregates in the cytoplasm and interstitial collagen and basement membranes. Pentosidine content was increased in cytoskeletal and myelin protein extracts of the sural nerve of human subjects and cytoskeletal proteins of the sciatic nerve of streptozotocin-induced diabetic rats. AGEs in the sciatic nerve of diabetic rats were decreased by islet transplantation. Improved glycemic control of diabetic patients may be expected to decrease protein glycation in the nerve. Protein glycation may decrease cytoskeletal assembly, induce protein aggregation, and provide ligands for cells surface receptors. The receptor for advanced glycation and products (RAGE) was expressed in peripheral neurons. It is probable that high intracellular glucose concentration is an important trigger for increased glycation, leading to increased formation of methylglyoxal, glyoxal, and 3-deoxyglucosone that glycate proteins to form AGEs intracellularly and extracellularly. Oxidative stress enhances these processes and is, in turn, enhanced by AGE/RAGE interactions. An established therapeutic strategy to prevent glycation is the use of alpha-oxoaldehyde scavengers. Available therapeutic options for trial are high-dose nicotinamide and thiamine therapies to prevent methylglyoxal formation. Future possible therapeutic strategies are RAGE antagonists and inducers of the enzymatic antiglycation defense. More research is required to understand the role of glycation in the development of diabetic neuropathy.
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Affiliation(s)
- Paul J Thornalley
- Department of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, United Kingdom
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369
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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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370
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Fan X, Subramaniam R, Weiss MF, Monnier VM. Methylglyoxal-bovine serum albumin stimulates tumor necrosis factor alpha secretion in RAW 264.7 cells through activation of mitogen-activating protein kinase, nuclear factor kappaB and intracellular reactive oxygen species formation. Arch Biochem Biophys 2003; 409:274-86. [PMID: 12504894 DOI: 10.1016/s0003-9861(02)00599-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Accumulating evidence suggests that the pathophysiology of diabetes is analogous to chronic inflammatory states. Circulating levels of inflammatory cytokines such as IL-6 and tumor necrosis factor alpha (TNFalpha) are increased in both type 1 and type 2 diabetes. TNFalpha plays an important role in the pathogenesis of insulin resistance in type 2 diabetes. However, the reason for this increase remains unclear. Levels of the dicarbonyl methylglyoxal (MGO) are elevated in diabetic plasma and MGO-modified bovine serum albumin (MGO-BSA) can trigger cellular uptake of TNF. Therefore we tested the hypothesis that MGO-modified proteins may cause TNFalpha secretion in macrophage-like RAW 264.7 cells. Treatment of cells with MGO-BSA induced TNFalpha release in a dose-dependent manner. MGO-modified ribonuclease A and chicken egg ovalbumin had similar effects. Cotreatment of cells with antioxidant reagent N-acetylcysteine (NAC) inhibited MGO-BSA-induced TNFalpha secretion. MGO-BSA stimulated the simultaneous activation of p44/42 and p38 mitogen-activated protein kinase. PD98059, a selective MEK inhibitor, inhibited MGO-BSA-induced TNFalpha release as well as ERK phosphorylation. Pretreatment of cells with NAC also resulted in inhibition of MGO-BSA-induced ERK phosphorylation. MGO-BSA induced dose-dependent NFkappaB activation as shown by electrophoresis mobility shift assay. The MGO-BSA-induced NFkappaB activation was prevented in the presence of PD98059, NAC, and parthenolide, a selective inhibitor of NFkappaB. Furthermore, the NFkappaB inhibitor parthenolide suppressed MGO-BSA-induced TNFalpha secretion. Confocal microscopy using dichlorofluorescein to demonstrate intracellular reactive oxygen species (ROS) showed that MGO-BSA produced more ROS compared with native BSA. MGO-BSA could also stimulate protein kinase C (PKC) translocation to the cell membrane, considered a key signaling pathway in diabetes. However, there was no evidence that PKC was involved in TNFalpha release based on inhibition by calphostin C and staurosporine. Our findings suggest that the presence of chronically elevated levels of MGO-modified bovine serum albumin may contribute to elevated levels of TNFalpha in diabetes.
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Affiliation(s)
- X Fan
- Institute of Pathology, Case Western Reserve University, Clevelard, OH 44106, USA
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371
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372
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Mearini E, Romani R, Mearini L, Antognelli C, Zucchi A, Baroni T, Porena M, Talesa VN. Differing expression of enzymes of the glyoxalase system in superficial and invasive bladder carcinomas. Eur J Cancer 2002; 38:1946-50. [PMID: 12204678 DOI: 10.1016/s0959-8049(02)00236-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This work aimed to study the activities of the glyoxalase system enzymes (glyoxalase I (GI) and glyoxalase II (GII) and their gene expression in human bladder carcinomas compared with the corresponding normal mucosa. Samples of these tissues were collected from 26 patients with superficial (SBC) or invasive bladder cancer (IBC) and used to evaluate enzyme activity and gene expression by northern blot analysis. In keeping with the electrophoretic pattern and the expression level of the respective genes, GI activity significantly increased in SBC samples, while it remained unchanged in IBC samples compared with the normal mucosa. In contrast, GII showed a higher activity in the tumour (either SBC or IBC samples) versus normal tissues. These results confirm the role of the glyoxalases in detoxifying cytotoxic methylglyoxal (MG) in bladder cancer. The differing levels of GI activity level and gene expression of GI between the SBC and IBC samples could help in their differential diagnosis.
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Affiliation(s)
- E Mearini
- Department of Medical and Surgical Specialities, Division of Urology, University of Perugia, Policlinico Monteluce, 06122 Perugia, Italy
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373
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Denis U, Lecomte M, Paget C, Ruggiero D, Wiernsperger N, Lagarde M. Advanced glycation end-products induce apoptosis of bovine retinal pericytes in culture: involvement of diacylglycerol/ceramide production and oxidative stress induction. Free Radic Biol Med 2002; 33:236-47. [PMID: 12106819 DOI: 10.1016/s0891-5849(02)00879-1] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
One of the earliest changes observed in retinal microvessels in diabetic retinopathy is the selective loss of intramural pericytes. We tested the hypothesis that AGE might be involved in the disappearance of retinal pericytes by apoptosis and further investigated the signaling pathway leading to cell death. Chronic exposure of pericytes to methylglyoxal-modified bovine serum albumin (AGE-BSA) (3 microM) leads to a 3-fold increase of apoptosis (8.9 +/- 1.1%), associated with an increase in cellular ceramide (185 +/- 12%) and diacylglycerol (194 +/- 9%) levels. Ceramide formation was almost inhibited (95%) by an acidic sphingomyelinase inhibitor, desipramine (0.3 microM). Dual inhibition of ceramide (95%) and diacylglycerol (80%) production was observed with a phosphatidylcholine-phospholipase C inhibitor, D609 (9.4 microM). Taken together, these results suggest activation of phosphatidylcholine-phospholipase C coupled to acidic sphingomyelinase. However, both inhibitors only partially protected pericytes against apoptosis, suggesting another apoptotic pathway independent of diacylglycerol/ceramide production. Treatments with various antioxidants completely inhibited pericyte apoptosis, suggesting oxidative stress induction during this apoptotic process. Inhibition of diacylglycerol/ceramide production by N-acetyl-L-cysteine suggests that oxidative stress acts upstream of the two metabolic pathways. AGE treated with metal chelators were also able to induce pericyte apoptosis, suggesting a specific effect of AGE on intracellular oxidative stress independent of redox-active metal ions bound to AGE. In conclusion, these results identify new biochemical targets involved in pericyte loss, which can provide new therapeutic perspectives in diabetic retinopathy.
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Affiliation(s)
- Ulriche Denis
- Diabetic Microangiopathy Unit, LIPHA-INSERM U352, INSA-Lyon, Villeurbanne Cedex, France
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374
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Morgan PE, Dean RT, Davies MJ. Inactivation of cellular enzymes by carbonyls and protein-bound glycation/glycoxidation products. Arch Biochem Biophys 2002; 403:259-69. [PMID: 12139975 DOI: 10.1016/s0003-9861(02)00222-9] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Diabetic plasma contains elevated levels of glucose and various low-molecular-weight carbonyl compounds derived from the metabolism of glucose and related materials. These compounds react with protein side chains (Arg, Lys, Cys, and His) to give glycated materials and advanced glycation end products. In this study, we have examined the effect of glucose and carbonyl compounds (methylglyoxal, glyoxal, glycolaldehyde, and hydroxyacetone), and glycation products arising from reaction of these materials with model proteins, on the activity of three key cellular enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glutathione reductase, and lactate dehydrogenase, both in isolation and in cell lysates. In contrast to glucose (1M, both fresh and aged for 8 weeks), which had no effect, marked inhibition of all three enzymes was observed with methylglyoxal and glyoxal. GAPDH was also inhibited by glycolaldehyde and hydroxyacetone. Incubation of these enzymes with proteins that had been preglycated with methylglyoxal, but not glucose, also resulted in significant time- and concentration-dependent inhibition with both isolated enzymes and cell lysates. This inhibition was not metal ion, oxygen, superoxide dismutase, or catalase dependent, suggesting that inhibition is not radical mediated. These effects are suggested to be due to direct adduction of the free- or protein-bound carbonyls with the target enzyme. Such an interpretation is supported by the detection of the loss of thiol groups on GAPDH and the detection of cross-linked materials on protein gels. Though direct comparison of the extent of inhibition induced by free versus protein-bound carbonyls was not possible, the significantly higher concentrations of the latter materials over the former in diabetic plasma and cells lead us to suggest that alterations in the activity of key cellular enzymes induced by glycated proteins may play a significant role in the development of diabetic complications.
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Affiliation(s)
- Philip E Morgan
- The Heart Research Institute, 145 Missenden Road, Camperdown NSW 2050, Australia
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375
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Biemel KM, Friedl DA, Lederer MO. Identification and quantification of major maillard cross-links in human serum albumin and lens protein. Evidence for glucosepane as the dominant compound. J Biol Chem 2002; 277:24907-15. [PMID: 11978796 DOI: 10.1074/jbc.m202681200] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycation reactions leading to protein modifications (advanced glycation end products) contribute to various pathologies associated with the general aging process and long term complications of diabetes. However, only few relevant compounds have so far been detected in vivo. We now report on the first unequivocal identification of the lysine-arginine cross-links glucosepane 5, DOGDIC 6, MODIC 7, and GODIC 8 in human material. For their accurate quantification by coupled liquid chromatography-electrospray ionization mass spectrometry, (13)C-labeled reference compounds were synthesized independently. Compounds 5-8 are formed via the alpha-dicarbonyl compounds N(6)-(2,3-dihydroxy-5,6-dioxohexyl)-l-lysinate (1a,b), 3-deoxyglucosone (), methylglyoxal (), and glyoxal (), respectively. The protein-bound dideoxyosone 1a,b seems to be of prime significance for cross-linking because it presumably is not detoxified by mammalian enzymes as readily as 2-4. Hence, the follow-up product glucosepane 5 was found to be the dominant compound. Up to 42.3 pmol of 5/mg of protein was identified in human serum albumin of diabetics; the level of 5 correlates markedly with the glycated hemoglobin HbA(1c). In the water-insoluble fraction of lens proteins from normoglycemics, concentration of 5 ranges between 132.3 and 241.7 pmol/mg. The advanced glycoxidation end product GODIC 8 is elevated significantly in brunescent lenses, indicating enhanced oxidative stress in this material. Compounds 5-8 thus appear predestined as markers for pathophysiological processes.
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Affiliation(s)
- Klaus M Biemel
- Institut für Lebensmittelchemie (170), Universität Hohenheim, Garbenstrasse 28, Stuttgart D-70593, Germany
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376
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Scirè A, Saccucci F, Bertoli E, Cambria MT, Principato G, D'Auria S, Tanfani F. Effect of acidic phospholipids on the structural properties of recombinant cytosolic human glyoxalase II. Proteins 2002; 48:126-33. [PMID: 12012344 DOI: 10.1002/prot.10149] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A peculiar characteristic of highly concentrated cytosolic recombinant human glyoxalase II (GII) solutions is to undergo partial precipitation. Previous work indicated that anionic phospholipids (PLs) exert a noncompetitive inhibition on the enzymatic activity of the soluble enzyme. In this study, FTIR spectroscopy was used to analyze the structural properties and the thermal stability of the soluble protein in the absence and in the presence of liposomes made of different phospholipids (PLs). The structural analysis was performed on the precipitate as well. The interaction of acidic PLs with GII lowered the thermal stability of the enzyme and inhibited protein intermolecular interactions (aggregation) brought about by thermal denaturation. Infrared data indicated that ionic and hydrophobic interactions occur between GII and acidic PLs causing small changes in the secondary structure of the enzyme. No interactions of the protein with egg phosphatidylcholine liposomes were detected. The results are consistent with the destabilization of the protein tertiary structure, and indicate that GII possesses hydrophobic part(s) that interact with the acyl chains of PLs. Data on precipitated GII did not show remarkable modification of secondary structure, suggesting that hydrophobic stretches of the enzyme may also be involved in the protein-protein association (precipitation) at high GII concentration. The alterations in the GII structure and the noncompetitive inhibition exerted by acidic PLs are strictly related.
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Affiliation(s)
- Andrea Scirè
- Institute of Biochemistry, University of Ancona, Via Ranieri, Ancona, Italy
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377
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Amicarelli F, Colafarina S, Cesare P, Aimola P, Di Ilio C, Miranda M, Ragnelli AM. Morphofunctional mitochondrial response to methylglyoxal toxicity in Bufo bufo embryos. Int J Biochem Cell Biol 2001; 33:1129-39. [PMID: 11551828 DOI: 10.1016/s1357-2725(01)00010-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Methylglyoxal (2-oxopropanal) is a reactive alpha-oxoaldehyde that can be formed endogenously mainly as a by-product of glycolytic pathway. It is a cytotoxic compound with significant antiproliferative properties as it can bind, under physiological conditions, to nucleic acids and proteins, forming stable adducts. We have recently shown that exogenous methylglyoxal (150-600 microM) is highly toxic for amphibian embryos where it produces, when added to the culture water, inhibition of cell proliferation in the early developmental stages, followed by severe malformations and strongly reduced embryonic viability. In this work we investigate the morphofunctional effect of methylglyoxal on the common toad B. bufo embryo mitochondria in order to verify if its dysmorphogenetic action might be also ascribed to impairment of mitochondrial functions. The mitochondria were isolated from embryos at the developmental stages of morula, neural plate and operculum complete and developing in the presence of 600 microM methylglyoxal. The results show that exogenous methylglyoxal is highly toxic at mitochondrial level, where it produces proliferation, swelling and membrane derangement. As a consequence, mitochondria from treated embryos show decreased oxidative phosphorylation efficiency, as indicated by the significant reduction both of the respiratory control index values and of the embryonic ATP content. On the basis of these data, it is possible that the methylglyoxal-induced embryonic malformations as well as the strongly reduced viability might be also ascribed to energy depletion.
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Affiliation(s)
- F Amicarelli
- Dipartimento di Biologia di Base ed Applicata, Facoltà di Scienze, Università degli Studi di L'Aquila, Coppito 67100, L'Aquila, Italy.
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378
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Rulli A, Carli L, Romani R, Baroni T, Giovannini E, Rosi G, Talesa V. Expression of glyoxalase I and II in normal and breast cancer tissues. Breast Cancer Res Treat 2001; 66:67-72. [PMID: 11368412 DOI: 10.1023/a:1010632919129] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The present work aimed to study the activities of glyoxalase system enzymes, glyoxalase I (G I) and glyoxalase II (G II), as well as the expression of their genes in human breast carcinoma. Samples of tumoral tissue and normal counterparts were drawn from several patients during surgery. They served either for preparing extracts to be used in enzyme activity evaluations or for RNA extraction and subsequent northern blot analysis. A far higher activity level of G I and G II occurs in the tumor compared with pair-matched normal tissue, as shown by both spectrophotometrical assay and electrophoretic pattern. Such increased activities of G I and G II likely result from an enhanced enzyme synthesis as a consequence of increased expression of the respective genes in the tumoral tissue, as evidenced by northern blot. The present findings confirm a key-role of glyoxalase system to detoxify cytotoxic methylglyoxal and modulate S-D-lactoylglutathione levels in tumor cells. Moreover, they suggest a possible employment of GI inhibitors as anti-cancer drugs.
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Affiliation(s)
- A Rulli
- Department of Surgical Sciences, University of Perugia, Italy
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379
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Murata-Kamiya N, Kamiya H. Methylglyoxal, an endogenous aldehyde, crosslinks DNA polymerase and the substrate DNA. Nucleic Acids Res 2001; 29:3433-8. [PMID: 11504881 PMCID: PMC55850 DOI: 10.1093/nar/29.16.3433] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2001] [Revised: 06/29/2001] [Accepted: 06/29/2001] [Indexed: 11/14/2022] Open
Abstract
Methylglyoxal, a known endogenous and environmental mutagen, is a reactive alpha-ketoaldehyde that can modify both DNA and proteins. To investigate the possibility that methylglyoxal induces a crosslink between DNA and DNA polymerase, we treated a 'primed template' DNA and the exonuclease-deficient Klenow fragment (KF(exo-)) of DNA polymerase I with methylglyoxal in vitro. When the reaction mixtures were analyzed by SDS-PAGE, we found that methylglyoxal induced a DNA-KF(exo-) crosslink. The specific binding complex of KF(exo-) and 'primed template' DNA was necessary for formation of the DNA-KF(exo-) crosslink. Methylglyoxal reacted with guanine residues in the single-stranded portion of the template DNA. When 2'-deoxyguanosine was incubated with Nalpha-acetyllysine or N-acetylcysteine in the presence of methylglyoxal, a crosslinked product was formed. No other amino acid derivatives tested could generate a crosslinked product. These results suggest that methylglyoxal crosslinks a guanine residue of the substrate DNA and lysine and cysteine residues near the binding site of the DNA polymerase during DNA synthesis and that DNA replication is severely inhibited by the methylglyoxal-induced DNA-DNA polymerase crosslink.
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Affiliation(s)
- N Murata-Kamiya
- Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan
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380
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Akhand AA, Hossain K, Mitsui H, Kato M, Miyata T, Inagi R, Du J, Takeda K, Kawamoto Y, Suzuki H, Kurokawa K, Nakashima I. Glyoxal and methylglyoxal trigger distinct signals for map family kinases and caspase activation in human endothelial cells. Free Radic Biol Med 2001; 31:20-30. [PMID: 11425486 DOI: 10.1016/s0891-5849(01)00550-0] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Carbonyl compounds with diverse carbon skeletons may be differentially related to the pathogenesis of vascular diseases. In this study, we compared intracellular signals delivered into cultured human umbilical vein endothelial cells (HUVECs) by glyoxal (GO) and methylglyoxal (MGO), which differ only by a methyl group. Depending on their concentrations, GO and MGO promoted phosphorylations of ERK1 and ERK2, which were blocked by the protein-tyrosine kinase (PTK) inhibitors herbimycin A and staurosporine, thereby being PTK-dependent. GO and MGO also induced phosphorylations of JNK, p38 MAPK, and c-Jun, either PTK-dependently (GO) or -independently (MGO). Next, we found that MGO, but not GO, induced degradation of poly(ADP-ribose) polymerase (PARP) as the intracellular substrate of caspase-3. Curcumin and SB203580, which inhibit JNK and p38 MAPK signaling pathways, but not herbimycin A/staurosporine, prevented the MGO-induced PARP degradation. We then found that MGO, but not GO, reduced the intracellular glutathione level, and that cysteine, but not cystine, inhibited the MGO-mediated activation of ERK, JNK, p38 MAPK, or c-Jun more extensively than did lysine or arginine. In addition, all the signals triggered by GO and MGO were blocked by amino guanidine (AG), which traps carbonyls. These results demonstrated that GO and MGO triggered two distinct signal cascades, one for PTK-dependent control of ERK and another for PTK-independent redox-linked activation of JNK/p38 MAPK and caspases in HUVECs, depending on the structure of the carbon skeleton of the chemicals.
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Affiliation(s)
- A A Akhand
- Department of Immunology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Japan
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381
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Martins AM, Cordeiro CA, Ponces Freire AM. In situ analysis of methylglyoxal metabolism in Saccharomyces cerevisiae. FEBS Lett 2001; 499:41-4. [PMID: 11418108 DOI: 10.1016/s0014-5793(01)02519-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Methylglyoxal metabolism was studied during Saccharomyces cerevisiae grown with D-glucose as the sole carbon and energy source. Using for the first time a specific assay for methylglyoxal in yeast, metabolic fluxes of its formation and D-lactate production were determined. D-Glucose consumption and ethanol production were determined during growth. Metabolic fluxes were also determined in situ, at the glycolytic triose phosphate levels and glyoxalase pathway. Maximum fluxes of ethanol production and glucose consumption correspond to maxima of methylglyoxal and D-lactate formation fluxes during growth. Methylglyoxal formation is quantitatively related to glycolysis, representing 0.3% of the total glycolytic flux in S. cerevisiae.
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Affiliation(s)
- A M Martins
- Grupo de Enzimologia, Centro de Estudos de Bioquímica e Fisiologia, and Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, 1749-016, Lisbon, Portugal
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382
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Beisswenger PJ, Howell SK, O'Dell RM, Wood ME, Touchette AD, Szwergold BS. alpha-Dicarbonyls increase in the postprandial period and reflect the degree of hyperglycemia. Diabetes Care 2001; 24:726-32. [PMID: 11315838 DOI: 10.2337/diacare.24.4.726] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Chronic hyperglycemia is known to increase tissue glycation and diabetic complications, but controversy exists regarding the independent role of increased postprandial glucose excursions. To address this question, we have studied the effect of postprandial glycemic excursions (PPGEs) on levels of methylglyoxal (MG) and 3-deoxyglucosone (3-DG), two highly reactive precursors of advanced glycation end products (AGEs). RESEARCH DESIGN AND METHODS We performed 4-month crossover studies on 21 subjects with type 1 diabetes and compared the effect of premeal insulin lispro or regular insulin on PPGEs and MG/3-DG excursions. PPGE was determined after standard test meal (STMs) and by frequent postprandial glucose monitoring. HbA1c and postprandial MG and D-lactate were measured by HPLC, whereas 3-DG was determined by gas chromatography/mass spectroscopy. RESULTS Treatment with insulin lispro resulted in a highly significant reduction in PPGEs relative to the regular insulin-treated group (P = 0.0005). However, HbA1c levels were similar in the two groups, and no relationship was observed between HbA1c and PPGE (P = 0.93). Significant postprandial increases in MG, 3-DG, and D-lactate occurred after the STM. Excursions of MG and 3-DG were highly correlated with levels of PPGE (R = 0.55, P = 0.0002 and R = 0.61, P = 0.0004; respectively), whereas a significant inverse relationship was seen between PPGE and D-lactate excursions (R = 0.40, P = 0.01). Conversely, no correlation was observed between HbAlc and postprandial MG, 3-DG, or D-lactate levels. CONCLUSIONS Increased production of MG and 3-DG occur with greater PPGE, whereas HbA1c does not reflect these differences. Reduced PPGE also leads to increased production of D-lactate, indicating a role for increased detoxification in reducing MG levels. The higher postprandial levels of MG and 3-DG observed with greater PPGE may provide a partial explanation for the adverse effects of glycemic lability and support the value of agents that reduce glucose excursions.
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Affiliation(s)
- P J Beisswenger
- Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA.
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383
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Chatterjee R, Millard CS, Champion K, Clark DP, Donnelly MI. Mutation of the ptsG gene results in increased production of succinate in fermentation of glucose by Escherichia coli. Appl Environ Microbiol 2001; 67:148-54. [PMID: 11133439 PMCID: PMC92534 DOI: 10.1128/aem.67.1.148-154.2001] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli NZN111 is blocked in the ability to grow fermentatively on glucose but gave rise spontaneously to a mutant that had this ability. The mutant carries out a balanced fermentation of glucose to give approximately 1 mol of succinate, 0. 5 mol of acetate, and 0.5 mol of ethanol per mol of glucose. The causative mutation was mapped to the ptsG gene, which encodes the membrane-bound, glucose-specific permease of the phosphotransferase system, protein EIICB(glc). Replacement of the chromosomal ptsG gene with an insertionally inactivated form also restored growth on glucose and resulted in the same distribution of fermentation products. The physiological characteristics of the spontaneous and null mutants were consistent with loss of function of the ptsG gene product; the mutants possessed greatly reduced glucose phosphotransferase activity and lacked normal glucose repression. Introduction of the null mutant into strains not blocked in the ability to ferment glucose also increased succinate production in those strains. This phenomenon was widespread, occurring in different lineages of E. coli, including E. coli B.
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Affiliation(s)
- R Chatterjee
- Environmental Research Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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384
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Abstract
In this article we will review the clinical signs and symptoms of diabetic somatic polyneuropathy (DPN), its prevalence and clinical management. Staging and classification of DPN will be exemplified by various staging paradigms of varied sophistication. The results of therapeutic clinical trials will be summarized. The pathogenesis of diabetic neuropathy reviews an extremely complex issue that is still not fully understood. Various recent advances in the understanding of the disease will be discussed, particularly with respect to the differences between neuropathy in the two major types of diabetes. The neuropathology and natural history of diabetic neuropathy will be discussed pointing out the heterogeneities of the disease. Finally, the various prospective therapeutic avenues will be dealt with and discussed.
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Affiliation(s)
- K Sugimoto
- Department of Pathology, Wayne State University, School of Medicine and Detroit Medical Center, Detroit, MI 48201, USA
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385
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Rahbar S, Natarajan R, Yerneni K, Scott S, Gonzales N, Nadler JL. Evidence that pioglitazone, metformin and pentoxifylline are inhibitors of glycation. Clin Chim Acta 2000; 301:65-77. [PMID: 11020463 DOI: 10.1016/s0009-8981(00)00327-2] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Enhanced formation and accumulation of advanced glycation end products (AGEs) have been proposed to play a major role in the pathogenesis of diabetic complications, and atherosclerosis, leading to the development of a range of diabetic complications including nephropathy, retinopathy and neuropathy. Several potential drug candidates as AGE inhibitors have been reported recently. Aminoguanidine is the first drug extensively studied. However, there are no currently available medications known to block AGE formation. We have previously reported a number of novel and structurally diverse compounds as potent inhibitors of glycation and AGE formation. We have now studied several of the existing drugs, which are in therapeutic practice for lowering blood sugar or the treatment of peripheral vascular disease in diabetic patients, for possible inhibitory effects on glycation. We show that that three compounds; pioglitazone, metformin and pentoxifylline are also inhibitors of glycation.
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Affiliation(s)
- S Rahbar
- Department of Diabetes, Endocrinology and Metabolism, The Leslie and Susan Gonda (Goldschmied) Diabetes and Genetic Research Building, City of Hope National Medical Center, Duarte, CA 91010, USA.
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386
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Léránt I, Kolev K, Gombás J, Machovich R. Modulation of plasminogen activation and plasmin activity by methylglyoxal modification of the zymogen. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1480:311-20. [PMID: 10899632 DOI: 10.1016/s0167-4838(00)00083-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effect of methylglyoxal on the plasminogen-plasmin system is studied. Treatment of plasminogen with methylglyoxal at a 20-fold molar excess results in covalent modification of the molecule as evidenced by the decreased number of NH(2) side chains, arginine side chain residues and the new band in the non-tryptophan dependent fluorescent spectrum. This structural modification is associated with profound functional alterations: the rate of activation by streptokinase, tissue-type plasminogen activator, urokinase-type plasminogen activator and trypsin decreases and the amidolytic activity of the generated plasmin is impaired. Plasmin treatment with methylglyoxal on the other hand does not alter its steady-state kinetic parameters on a peptidyl-anilide synthetic substrate, indicating that modification susceptible side chains are sensitive to methylglyoxal only in the zymogen. Our data suggest that in vivo fibrinolysis could be impaired under pathological conditions, e.g. increased methylglyoxal formation in diabetes mellitus.
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Affiliation(s)
- I Léránt
- Department of Medical Biochemistry at Semmelweis University, Budapest, Hungary
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387
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Murata-Kamiya N, Kamiya H, Kaji H, Kasai H. Methylglyoxal induces G:C to C:G and G:C to T:A transversions in the supF gene on a shuttle vector plasmid replicated in mammalian cells. Mutat Res 2000; 468:173-82. [PMID: 10882894 DOI: 10.1016/s1383-5718(00)00044-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We previously reported that the majority of base-pair substitutions induced by an endogenous mutagen, methylglyoxal, were G:C-->T:A transversions and G:C-->A:T transitions in wild-type and nucleotide excision repair (NER)-deficient (uvrA or uvrC) Escherichia coli strains. To investigate the mutation spectrum of methylglyoxal in mammalian cells and to compare the spectrum with those detected in other experimental systems, we analyzed mutations in a bacterial suppressor tRNA (supF) gene in the shuttle vector plasmid pMY189. We treated pMY189 with methylglyoxal and immediately transfected it into simian COS-7 cells. The cytotoxicity and the mutation frequency (MF) increased according to the dose of methylglyoxal. In the mutants induced by methylglyoxal, multi-base deletions were predominant (50%), followed by base-pair substitutions (35%), in which 89% of the substitutions occurred at G:C sites. Among them, G:C-->C:G and G:C-->T:A transversions were predominant. The overall distribution of methylglyoxal-induced mutations detected in the supF gene was different from that for the spontaneous mutations. These results suggest that methylglyoxal may take part in causing G:C-->C:G and G:C-->T:A transversions in vivo.
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Affiliation(s)
- N Murata-Kamiya
- Department of Health Policy and Management, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Kitakyushu, Japan
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388
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Rahbar S, Yerneni KK, Scott S, Gonzales N, Lalezari I. Novel inhibitors of advanced glycation endproducts (part II). MOLECULAR CELL BIOLOGY RESEARCH COMMUNICATIONS : MCBRC 2000; 3:360-6. [PMID: 11032758 DOI: 10.1006/mcbr.2000.0239] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Enhanced formation and accumulation of advanced glycation endproducts (AGEs), have been implicated as a major pathogenesis process leading to diabetic complications, normal aging, atherosclerosis, and Alzheimer's Disease. Several potential drug candidates as AGE inhibitors have been reported recently. The aim of this study was to develop classes of novel inhibitors of glycation, AGE formation, and AGE-crosslinking and to investigate their effects through in vitro chemical and immunochemical assays. A total of 92 compounds were designed and synthesized. The first 63 compounds were reported before. Nearly half of the 29 novel inhibitors reported here are benzoic acid derivatives and related molecules, and found to be potent inhibitors of multistage glycation, AGE formation, and AGE-protein crosslinking. All 29 compounds show some degrees of inhibitory activities as detected by the four assay methods, 9 compounds demonstrated high percent inhibition (PI) in all tests, 30 to 40 times stronger than aminoguanidine.
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Affiliation(s)
- S Rahbar
- Department of Diabetes, City of Hope National Medical Center, Duarte, California, 91010, USA.
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389
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Abstract
Phospholipid-linked glycation products are supposed to play an important role in lipid oxidation in vivo. Independent syntheses and unequivocal structural characterization are reported for the phosphatidyl ethanolamine (PE)-derived Amadori compound 4-hydroxy-4-oxo-1-[(palmitoyloxy)methyl]-9-(2,3,4,5-tetrahydrox ytetrahydro-2H-pyran-2-yl)-3,5-dioxa-8-aza-4lambda5-ph osphanon-1-yl palmitate, pyrrolecarbaldehyde 2-[[[2-[2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl]ethoxy](hydroxy)phosph oryl]oxy]-1-[(palmitoyloxy)methyl]ethyl palmitate, the carboxymethyl (CM) derivative 7-hydroxy-7,13-dioxo-10-(palmitoyloxy)-6,8,12-trioxa-3-aza-+ ++7lambda5-phosphaoctacosan-1-oic acid, and the carboxyethyl (CE) derivative 7-hydroxy-2-methyl-7,13-dioxo-10-(palmitoyloxy)-6,8,12-trioxa++ +-3-aza-7lambda5-phosphaoctacosan-l-oic acid. With these reference compounds, a liquid chromatography-mass spectrometry (LCMS) method for the determination of such PE-linked Maillard products has been developed.
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Affiliation(s)
- C M Utzmann
- Institut für Lebensmittelchemie, Universität Hohenheim, Stuttgart, Germany
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390
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Bacchiocchi S, Principato G. Mitochondrial contribution to metabolic changes in the digestive gland of Mytilus galloprovincialis during anaerobiosis. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2000; 286:107-13. [PMID: 10617851 DOI: 10.1002/(sici)1097-010x(20000201)286:2<107::aid-jez1>3.0.co;2-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The activities of several enzymes and the levels of metabolites have been measured in the digestive gland of Mytilus galloprovincialis exposed to increasing hypoxia from 7 to 168 hr. A sharp decrease of pyruvate kinase was observed after 7 hr. The anoxic enzyme showed increased Km for phosphoenolpyruvate and decreased apparent Ki for alanine. Glyoxalase I was constant after up to 72 hr of exposure and then decreased. Phosphoenolpyruvate carboxykinase and alanopine dehydrogenase decreased. The metabolites alanine and succinate increased with hypoxia time, whereas D- and L-lactic and aspartic acids were undetectable and constant respectively. Mitochondrial formation of pyruvate from D-lactate was demonstrated in intact mitochondria isolated from the digestive gland of Mytilus galloprovincialis. The significance of the observed enzyme and metabolite changes in hypoxia is discussed in comparison with other invertebrate organisms. The role of mitochondria in the overall adaptive strategy of Mytilus galloprovincialis is discussed. J. Exp. Zool. 286:107-113, 2000.
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Affiliation(s)
- S Bacchiocchi
- Istituto di Biologia e Genetica, Università di Ancona, 60100 Ancona, Italy
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391
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Tagami U, Akashi S, Mizukoshi T, Suzuki E, Hirayama K. Structural studies of the Maillard reaction products of a protein using ion trap mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2000; 35:131-138. [PMID: 10679972 DOI: 10.1002/(sici)1096-9888(200002)35:2<131::aid-jms920>3.0.co;2-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The early stage products of the Maillard reaction of egg white lysozyme with D-glucose were studied. Incubation with D-glucose at 50 degrees C for 20 days caused reaction on the Lys and Arg residues of lysozyme as follows: all of the six Lys residues and 10 of the 11 Arg residues in lysozyme reacted with D-glucose; Arg 61 did not react with D-glucose. The Lys residues reacted with D-glucose with 1 mol of dehydration per mole of residue, and the Arg residues reacted with 2 mol of dehydration per mole of residue. The major constituent of the Amadori product with the epsilon-amino group of the Lys residue and the D-glucose was found to be the beta-pyranose form. The structure of the early stage product of the Maillard reaction of a protein with a sugar is the same as that of an amino acid with a sugar.
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Affiliation(s)
- U Tagami
- Central Research Laboratories, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi 210-8681, Japan
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392
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Karg E, Németh I, Horányi M, Pintér S, Vécsei L, Hollán S. Diminished blood levels of reduced glutathione and alpha-tocopherol in two triosephosphate isomerase-deficient brothers. Blood Cells Mol Dis 2000; 26:91-100. [PMID: 10772880 DOI: 10.1006/bcmd.2000.0280] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The glutathione redox system and alpha-tocopherol, both of which are essential for maintaining the normal structure of biological membranes, some other lipid-soluble antioxidants (lycopene, beta-carotene, retinol), and lipid peroxidation, were investigated in the blood from two triosephosphate isomerase (TPI)-deficient brothers. Both of the genetically identical compound heterozygote brothers have congenital hemolytic anemia, but only one of them has a neurological defect, the second cardinal symptom of TPI deficiency. Whole blood reduced glutathione levels were markedly decreased in both brothers. The glutathione reductase activities as well as the NADPH contents of their erythrocytes were in the normal range or slightly enhanced. Increased ratio of oxidized/reduced glutathione, elevated glutathione S-transferase activity, and increased d-lactate level, a metabolite of the glyoxalase pathway, were detected only in the neurologically affected propositus. The plasma carotenoids (lycopene + beta-carotene), alpha-tocopherol/cholesterol + triglyceride ratios, and the erythrocyte alpha-tocopherol levels were significantly decreased in both patients. It seems conceivable that membrane alterations due to the low level of these reducing agents may contribute to the shortened life span of erythrocytes. The imbalance of the prooxidant/antioxidant homeostasis as well as the increased rate of methylglyoxal formation may also have been involved in the development of the neurological manifestations in the propositus.
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Affiliation(s)
- E Karg
- Department of Pediatrics, Albert Szent-Györgyi Medical University, Szeged, Hungary
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393
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Scir� A, Tanfani F, Saccucci F, Bertoli E, Principato G. Specific interaction of cytosolic and mitochondrial glyoxalase II with acidic phospholipids in form of liposomes results in the inhibition of the cytosolic enzyme only. Proteins 2000. [DOI: 10.1002/1097-0134(20001001)41:1<33::aid-prot60>3.0.co;2-n] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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394
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Obrosova IG, Fathallah L, Lang HJ. Interaction between osmotic and oxidative stress in diabetic precataractous lens: studies with a sorbitol dehydrogenase inhibitor. Biochem Pharmacol 1999; 58:1945-54. [PMID: 10591149 DOI: 10.1016/s0006-2952(99)00315-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Both sorbitol accumulation-linked osmotic stress and "pseudohypoxia" [increase in NADH/NAD+, similar to that in hypoxic tissues, and attributed to increased sorbitol dehydrogenase (1-iditol:NAD+ 5-oxidoreductase; EC 1.1.1.14; SDH) activity] have been invoked among the mechanisms underlying oxidative injury in target tissues for diabetic complications. We used the specific SDH inhibitor SDI-157 [2-methyl-4(4-N,N-dimethylaminosulfonyl-1-piperazino)pyrimid ine] to evaluate the role of osmotic stress versus "pseudohypoxia" in oxidative stress occurring in diabetic precataractous lens. Control and diabetic rats were treated with or without SDI-157 (100 mg/kg/day for 3 weeks). Lens malondialdehyde (MDA) plus 4-hydroxyalkenals (4-HA), MDA, GSH, and ascorbate levels, as well as the GSSG/GSH ratios, were similar in SDI-treated and untreated control rats, thus indicating that SDI-157 was not a prooxidant. Intralenticular osmotic stress, manifested by sorbitol levels, was more severe in SDI-treated diabetic rats (38.2+/-6.8 vs 21.2+/-3.5 micromol/g in untreated diabetic and 0.758+/-0.222 micromol/g in control rats, P<0.01 for both), while the decrease in the free cytosolic NAD+/NADH ratio was partially prevented (120+/-16 vs 88+/-11 in untreated diabetic rats and 143+/-13 in controls, P<0.01 for both). GSH and ascorbate levels were decreased, while MDA plus 4-HA and MDA levels were increased in diabetic rats versus controls; both antioxidant depletion and lipid aldehyde accumulation were exacerbated by SDI treatment. Superoxide dismutase (superoxide:superoxide oxidoreductase; EC 1.15.1.1), GSSG reductase (NAD[P]H:oxidized-glutathione oxidoreductase; EC 1.6.4.2), GSH transferase (glutathione S-transferase; EC 2.5.1.18), GSH peroxidase (glutathione:hydrogen-peroxide oxidoreductase; EC 1.11.1.9), and cytoplasmic NADH oxidase activities were increased in diabetic rats versus controls, and all the enzymes but GSH peroxidase were up-regulated further by SDI. In conclusion, sorbitol accumulation and osmotic stress generated oxidative stress in diabetic lens, whereas the contribution of "pseudohypoxia" was minor. SDIs provide a valuable tool for exploring mechanisms of oxidative injury in sites of diabetic complications.
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Affiliation(s)
- I G Obrosova
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0678, USA.
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395
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Lederer MO, Klaiber RG. Cross-linking of proteins by Maillard processes: characterization and detection of lysine-arginine cross-links derived from glyoxal and methylglyoxal. Bioorg Med Chem 1999; 7:2499-507. [PMID: 10632059 DOI: 10.1016/s0968-0896(99)00212-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Alpha-dicarbonyl compounds, such as glyoxal and methylglyoxal, are crucial intermediates in the browning and cross-linking of proteins by reducing sugars in the course of the Maillard reaction. The cross-linking units 2-ammonio-6-([2-[(4-ammonio-5-oxido-5-oxopentyl)amino]-4,5-dihydro - 1H-imidazol-5-ylidene]amino)hexanoate (9) and 2-ammonio-6-([2-[(4-ammonio-5-oxido-5-oxopentyl) amino]-4-methyl-4,5-dihydro-1H-imidazol-5-ylidene]amino)hexanoate (10), designated as GODIC and MODIC, are identified and quantified from glyoxal/methylglyoxal-bovine serum albumin (BSA) incubations. Independent syntheses and unequivocal structural characterization are given for 9 and 10. A protocol was established for their determination by liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI). BSA and the respective alpha-dicarbonyl compound were incubated at 37 degrees C, pH 7.4 for 1 week, and the time-dependent formation of 9 and 10 was observed. The maximum value obtained from a solution containing 50 g/L BSA and 2 mM glyoxal or methylglyoxal after a 7-day incubation period corresponds to an arginine derivatization quota of 13.0 +/- 0.32 mmol 9/mol Arg or 3.0 +/- 0.12 mmol 10/mol Arg. The cross-links 9 and 10 were also detected in a D-glucose-BSA incubation. From these results, it seems justified to assign an important role to 9 and 10 in the cross-linking of proteins in vivo as well as in foodstuffs. In an additional model study, formation of 9 and 10 was compared to that of the imidazolium cross-links GOLD 3 and MOLD 4.
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Affiliation(s)
- M O Lederer
- Institut für Lebensmittelchemie (170), Universität Hohenheim, Stuttgart, Germany.
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396
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Ankrah NA, Appiah-Opong R. Toxicity of low levels of methylglyoxal: depletion of blood glutathione and adverse effect on glucose tolerance in mice. Toxicol Lett 1999; 109:61-7. [PMID: 10514031 DOI: 10.1016/s0378-4274(99)00114-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Methylglyoxal, a metabolic by-product of glycolysis is also formed during food processing and has serious toxicological effects when in excess. In this study, ddY mice were exposed to low levels of methylglyoxal (1% v/v) via drinking water while in utero continuing until 2 months of age when investigations on blood GSH status and selected GSH dependent functions in the blood, and glucose tolerance were carried out. The results showed that GSH content was significantly decreased in the blood of methylglyoxal exposed mice when compared with controls (mean, 0.756 mmol/l vs. 1.090 mmol/l, p < 0.001). The data showed significant (p < 0.001) decreases in blood GSH-S-transferase activity and red blood cell (rbc) capacity to refract oxidative stress. Impaired glucose tolerance was 5.3 times more prevalent in the methylglyoxal exposed mice when compared with the controls. The results indicate that chronic intake of methylglyoxal, at levels that could be attained in food, is toxic by depletion of blood GSH and could have adverse effect on some GSH dependent functions in vivo.
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Affiliation(s)
- N A Ankrah
- Clinical Pathology Unit, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon.
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397
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Rahbar S, Kumar Yernini K, Scott S, Gonzales N, Lalezari I. Novel inhibitors of advanced glycation endproducts. Biochem Biophys Res Commun 1999; 262:651-6. [PMID: 10471380 DOI: 10.1006/bbrc.1999.1275] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Enhanced formation and accumulation of advanced glycation endproducts (AGE's) have been proposed to play a major role in the pathogenesis of diabetic complications, aging, atherosclerosis, and Alzheimer disease leading to progressive and irreversible intermolecular protein crosslinkings. This process is accelerated in diabetes and has been postulated to contribute to the development of a range of diabetic complications including nephropathy, retinopathy and neuropathy. Several potential drug candidates as AGE inhibitors have been reported recently. Aminoguanidine is the first drug extensively studied both in vitro and in vivo. We have developed a new class of compounds as potent inhibitors of glycation and AGE formation. The novel inhibitors reported here are aryl (and heterocyclic) ureido, and aryl (and heterocyclic) carboxamido phenoxy isobutyric acids and related molecules, which were found by in vitro assay methods to be potent inhibitors of multiple stage of glycation and AGE formation.
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Affiliation(s)
- S Rahbar
- Endocrinology & Metabolism, City of Hope National Medical Center, Duarte, California, 91010-0269, USA.
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398
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Oya T, Hattori N, Mizuno Y, Miyata S, Maeda S, Osawa T, Uchida K. Methylglyoxal modification of protein. Chemical and immunochemical characterization of methylglyoxal-arginine adducts. J Biol Chem 1999; 274:18492-502. [PMID: 10373458 DOI: 10.1074/jbc.274.26.18492] [Citation(s) in RCA: 277] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Methylglyoxal (MG), an endogenous metabolite that increases in diabetes and is a common intermediate in the Maillard reaction (glycation), reacts with proteins and forms advanced glycation end products. In the present study, we identify a novel MG-arginine adduct and also characterize the structure of a major fluorescent adduct. In addition, we describe the immunochemical study on the MG-arginine adducts using monoclonal antibody directed to MG-modified protein. Upon incubation of Nalpha-acetyl-L-arginine with MG at 37 degrees C, two nonfluorescent products and one fluorescent product were detected as the major products. The nonfluorescent products were identified as the Ndelta-(5-hydro-5-methyl-4-imidazolon-2-yl)-L-ornithine derivatives (5-hydro-5-methylimidazolone) and a novel MG-arginine adduct having a tetrahydropyrimidine moiety (Ndelta-(4-carboxy-4,6-dimethyl-5, 6-dihydroxy-1,4,5,6-tetrahydropyrimidine-2-yl)-L-ornithine). On the basis of the following chemical and spectroscopic evidence, the major fluorescent product, putatively identified as Ndelta-(5-methylimidazolon-2-yl)-L-ornithine (5-methylimidazolone), was found to be identical to Ndelta-(5-hydroxy-4, 6-dimethylpyrimidine-2-yl)-L-ornithine (argpyrimidine): (i) the low and high resolution fast atom bombardment-mass spectrometry gave a molecular ion peak at m/z of 297 (M+H) and a molecular formula of C10H25O6N4, respectively, which coincided with argpyrimidine; (ii) the 1H NMR spectrum of this product in d6-Me2SO showed a singlet at 2.10 ppm corresponding to six protons; (iii) the peak corresponding to the 5-methylimidazolone derivative was not detected by the liquid chromatography-mass spectrometry with the mode of selected ion monitoring; (iv) incubation of 5-hydro-5-methylimidazolone, a putative precursor of 5-methylimidazolone, at 37 degrees C for 14 days scarcely generated 5-methylimidazolone. On the other hand, as an immunochemical approach to the detection of these MG adducts, we raised the monoclonal antibodies (mAb3C and mAb6B) directed to the MG-modified protein and found that they specifically recognized the major fluorescent product, argpyrimidine, as the dominant epitope. The immunohistochemical analysis of the kidneys from diabetic patients revealed the localization of argpyrimidine in intima and media of small artery walls. Furthermore, the accumulation of argpyrimidine was also observed in some arterial walls of the rat brain after middle cerebral artery occlusion followed by reperfusion. These results suggest that argpyrimidine may contribute to the progression of not only long term diabetic complications, such as nephropathy and atherosclerosis, but also the tissue injury caused by ischemia/reperfusion.
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Affiliation(s)
- T Oya
- Laboratory of Food and Biodynamics, Nagoya University Graduate School of Bioagricultural Sciences, Nagoya 464-8601, Kobe University School of Medicine, Kobe 650-0017, Japan
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399
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Murata-Kamiya N, Kaji H, Kasai H. Deficient nucleotide excision repair increases base-pair substitutions but decreases TGGC frameshifts induced by methylglyoxal in Escherichia coli. Mutat Res 1999; 442:19-28. [PMID: 10366769 DOI: 10.1016/s1383-5718(99)00054-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
To investigate the mutation spectrum of a well-known mutagen, methylglyoxal, and the influence of nucleotide excision repair (NER) on methylglyoxal-induced mutations, we treated wild-type and NER-deficient (uvrA or uvrC) Escherichia coli strains with methylglyoxal, and analyzed mutations in the chromosomal lacI gene. In the three strains, the cell death and the mutation frequency increased according to the dose of methylglyoxal added to the culture medium. The frequencies of methylglyoxal-induced base-pair substitutions were higher in the NER-deficient strains than in the wild-type strain, in the presence and absence of mucAB gene. Paradoxically, the frequency of methylglyoxal-induced TGGC frameshifts was higher in the wild-type strain than in the NER-deficient strains. When the methylglyoxal-induced mutation spectra in the presence and absence of mucAB gene are compared, the ratios of base-pair substitutions to frameshifts were increased by the effects of mucAB gene. In the three strains, more than 75% of the base-pair substitutions occurred at G:C sites, independent of the mucAB gene. When the mucAB gene was present, G:C-->T:A transversions were predominant, followed by G:C-->A:T transitions. When the mucAB gene was absent, the predominant mutations differed in the three strains: in the wild-type and uvrC strains, G:C-->A:T transitions were predominant, followed by G:C-->T:A transversions, while in the uvrA strains, G:C-->T:A transversions were predominant, followed by G:C-->A:T transitions. These results suggest that NER may be involved in both the repair and the fixation of methylglyoxal-induced mutations.
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Affiliation(s)
- N Murata-Kamiya
- Department of Health Policy and Management, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan
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400
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Suzuki K, Koh YH, Taniguchi N. The cytotoxicity of methylglyoxal and 3-deoxyglucosone is decreased in the aldehyde reductase gene-transfected cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 463:509-15. [PMID: 10352726 DOI: 10.1007/978-1-4615-4735-8_64] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- K Suzuki
- Department of Biochemistry, Osaka University Medical School, Suita, Japan
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