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Glyoxylate protects against cyanide toxicity through metabolic modulation. Sci Rep 2022; 12:4982. [PMID: 35322094 PMCID: PMC8943054 DOI: 10.1038/s41598-022-08803-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 03/04/2022] [Indexed: 11/09/2022] Open
Abstract
Although cyanide's biological effects are pleiotropic, its most obvious effects are as a metabolic poison. Cyanide potently inhibits cytochrome c oxidase and potentially other metabolic enzymes, thereby unleashing a cascade of metabolic perturbations that are believed to cause lethality. From systematic screens of human metabolites using a zebrafish model of cyanide toxicity, we have identified the TCA-derived small molecule glyoxylate as a potential cyanide countermeasure. Following cyanide exposure, treatment with glyoxylate in both mammalian and non-mammalian animal models confers resistance to cyanide toxicity with greater efficacy and faster kinetics than known cyanide scavengers. Glyoxylate-mediated cyanide resistance is accompanied by rapid pyruvate consumption without an accompanying increase in lactate concentration. Lactate dehydrogenase is required for this effect which distinguishes the mechanism of glyoxylate rescue as distinct from countermeasures based solely on chemical cyanide scavenging. Our metabolic data together support the hypothesis that glyoxylate confers survival at least in part by reversing the cyanide-induced redox imbalances in the cytosol and mitochondria. The data presented herein represent the identification of a potential cyanide countermeasure operating through a novel mechanism of metabolic modulation.
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Patel SN, Parikh M, Lau-Cam CA. Impact of light ethanol intake and of taurine, separately and together, on pathways of glucose metabolism in the kidney of diabetic rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 803:279-303. [PMID: 25833505 DOI: 10.1007/978-3-319-15126-7_23] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sanket N Patel
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Jamaica, NY, USA
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3
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Lukovenkov AV, Varfolomeev SD, Petryaikina EE, Koltunov IE, Semenova NA. Stability of stationary states with variable concentration of hydrogen ions in enzyme systems: Applications to treatment of diabetic ketoacidosis. DOKL BIOCHEM BIOPHYS 2013; 449:94-8. [DOI: 10.1134/s1607672913020117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Indexed: 11/23/2022]
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4
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Gronemeyer T, Wiese S, Ofman R, Bunse C, Pawlas M, Hayen H, Eisenacher M, Stephan C, Meyer HE, Waterham HR, Erdmann R, Wanders RJ, Warscheid B. The proteome of human liver peroxisomes: identification of five new peroxisomal constituents by a label-free quantitative proteomics survey. PLoS One 2013; 8:e57395. [PMID: 23460848 PMCID: PMC3583843 DOI: 10.1371/journal.pone.0057395] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 01/24/2013] [Indexed: 01/11/2023] Open
Abstract
The peroxisome is a key organelle of low abundance that fulfils various functions essential for human cell metabolism. Severe genetic diseases in humans are caused by defects in peroxisome biogenesis or deficiencies in the function of single peroxisomal proteins. To improve our knowledge of this important cellular structure, we studied for the first time human liver peroxisomes by quantitative proteomics. Peroxisomes were isolated by differential and Nycodenz density gradient centrifugation. A label-free quantitative study of 314 proteins across the density gradient was accomplished using high resolution mass spectrometry. By pairing statistical data evaluation, cDNA cloning and in vivo colocalization studies, we report the association of five new proteins with human liver peroxisomes. Among these, isochorismatase domain containing 1 protein points to the existence of a new metabolic pathway and hydroxysteroid dehydrogenase like 2 protein is likely involved in the transport or β-oxidation of fatty acids in human peroxisomes. The detection of alcohol dehydrogenase 1A suggests the presence of an alternative alcohol-oxidizing system in hepatic peroxisomes. In addition, lactate dehydrogenase A and malate dehydrogenase 1 partially associate with human liver peroxisomes and enzyme activity profiles support the idea that NAD+ becomes regenerated during fatty acid β-oxidation by alternative shuttling processes in human peroxisomes involving lactate dehydrogenase and/or malate dehydrogenase. Taken together, our data represent a valuable resource for future studies of peroxisome biochemistry that will advance research of human peroxisomes in health and disease.
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Affiliation(s)
- Thomas Gronemeyer
- Department of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Sebastian Wiese
- Institut für Biologie II, Funktionelle Proteomik, Fakultät für Biologie and BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany
| | - Rob Ofman
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Christian Bunse
- Medizinisches Proteom-Center, Ruhr-Universität Bochum, Bochum, Germany
| | - Magdalena Pawlas
- Medizinisches Proteom-Center, Ruhr-Universität Bochum, Bochum, Germany
| | - Heiko Hayen
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Dortmund, Germany
| | - Martin Eisenacher
- Medizinisches Proteom-Center, Ruhr-Universität Bochum, Bochum, Germany
| | - Christian Stephan
- Medizinisches Proteom-Center, Ruhr-Universität Bochum, Bochum, Germany
| | - Helmut E. Meyer
- Medizinisches Proteom-Center, Ruhr-Universität Bochum, Bochum, Germany
| | - Hans R. Waterham
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Ralf Erdmann
- Abteilung für Systembiochemie, Medizinische Fakultät, Ruhr-Universität Bochum, Bochum, Germany
| | - Ronald J. Wanders
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Bettina Warscheid
- Institut für Biologie II, Funktionelle Proteomik, Fakultät für Biologie and BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany
- * E-mail:
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Dean JT, Rizk ML, Tan Y, Dipple KM, Liao JC. Ensemble modeling of hepatic fatty acid metabolism with a synthetic glyoxylate shunt. Biophys J 2010; 98:1385-95. [PMID: 20409457 DOI: 10.1016/j.bpj.2009.12.4308] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 12/06/2009] [Accepted: 12/11/2009] [Indexed: 11/29/2022] Open
Abstract
The liver plays a central role in maintaining whole body metabolic and energy homeostasis by consuming and producing glucose and fatty acids. Glucose and fatty acids compete for hepatic substrate oxidation with regulation ensuring glucose is oxidized preferentially. Increasing fatty acid oxidation is expected to decrease lipid storage in the liver and avoid lipid-induced insulin-resistance. To increase hepatic lipid oxidation in the presence of glucose, we previously engineered a synthetic glyoxylate shunt into human hepatocyte cultures and a mouse model and showed that this synthetic pathway increases free fatty acid beta-oxidation and confers resistance to diet-induced obesity in the mouse model. Here we used ensemble modeling to decipher the effects of perturbations to the hepatic metabolic network on fatty acid oxidation and glucose uptake. Despite sampling of kinetic parameters using the most fundamental elementary reaction models, the models based on current metabolic regulation did not readily describe the phenotype generated by glyoxylate shunt expression. Although not conclusive, this initial negative result prompted us to probe unknown regulations, and malate was identified as inhibitor of hexokinase 2 expression either through direct or indirect actions. This regulation allows the explanation of observed phenotypes (increased fatty acid degradation and decreased glucose consumption). Moreover, the result is a function of pyruvate-carboxylase, mitochondrial pyruvate transporter, citrate transporter protein, and citrate synthase activities. Some subsets of these flux ratios predict increases in fatty acid and decreases in glucose uptake after glyoxylate expression, whereas others predict no change. Altogether, this work defines the possible biochemical space where the synthetic shunt will produce the desired phenotype and demonstrates the efficacy of ensemble modeling for synthetic pathway design.
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Affiliation(s)
- Jason T Dean
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California, USA
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Cordero P, Campion J, Milagro FI, Marzo F, Martinez JA. Fat-to-glucose interconversion by hydrodynamic transfer of two glyoxylate cycle enzyme genes. Lipids Health Dis 2008; 7:49. [PMID: 19077206 PMCID: PMC2614421 DOI: 10.1186/1476-511x-7-49] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 12/10/2008] [Indexed: 11/10/2022] Open
Abstract
The glyoxylate cycle, which is well characterized in higher plants and some microorganisms but not in vertebrates, is able to bypass the citric acid cycle to achieve fat-to-carbohydrate interconversion. In this context, the hydrodynamic transfer of two glyoxylate cycle enzymes, such as isocytrate lyase (ICL) and malate synthase (MS), could accomplish the shift of using fat for the synthesis of glucose. Therefore, 20 mice weighing 23.37 +/- 0.96 g were hydrodinamically gene transferred by administering into the tail vein a bolus with ICL and MS. After 36 hours, body weight, plasma glucose, respiratory quotient and energy expenditure were measured. The respiratory quotient was increased by gene transfer, which suggests that a higher carbohydrate/lipid ratio is oxidized in such animals. This application could help, if adequate protocols are designed, to induce fat utilization for glucose synthesis, which might be eventually useful to reduce body fat depots in situations of obesity and diabetes.
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Affiliation(s)
- P Cordero
- Department of Nutrition and Food Sciences, Physiology and Toxicology, University of Navarra, Pamplona, Spain.
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Differential expression of liver proteins in streptozotocin-induced diabetic rats in response to hypoglycemic mushroom polysaccharides. KOREAN J CHEM ENG 2008. [DOI: 10.1007/s11814-008-0054-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Eprintsev AT, Shevchenko MY, Popov VN. Carbohydrate metabolism in the liver of rats in food deprivation and experimental diabetes. BIOL BULL+ 2008. [DOI: 10.1134/s1062359008010159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Kunze M, Pracharoenwattana I, Smith SM, Hartig A. A central role for the peroxisomal membrane in glyoxylate cycle function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1441-52. [PMID: 17055076 DOI: 10.1016/j.bbamcr.2006.09.009] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 09/05/2006] [Accepted: 09/06/2006] [Indexed: 11/18/2022]
Abstract
The glyoxylate cycle provides the means to convert C2-units to C4-precursors for biosynthesis, allowing growth on fatty acids and C2-compounds. The conventional view that the glyoxylate cycle is contained within peroxisomes in fungi and plants is no longer valid. Glyoxylate cycle enzymes are located both inside and outside the peroxisome. Thus, the operation of the glyoxylate cycle requires transport of several intermediates across the peroxisomal membrane. Glyoxylate cycle progression is also dependent upon mitochondrial metabolism. An understanding of the operation and regulation of the glyoxylate cycle, and its integration with cellular metabolism, will require further investigation of the participating metabolite transporters in the peroxisomal membrane.
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Affiliation(s)
- Markus Kunze
- Institute for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria.
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Kondrashov FA, Koonin EV, Morgunov IG, Finogenova TV, Kondrashova MN. Evolution of glyoxylate cycle enzymes in Metazoa: evidence of multiple horizontal transfer events and pseudogene formation. Biol Direct 2006; 1:31. [PMID: 17059607 PMCID: PMC1630690 DOI: 10.1186/1745-6150-1-31] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 10/23/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The glyoxylate cycle is thought to be present in bacteria, protists, plants, fungi, and nematodes, but not in other Metazoa. However, activity of the glyoxylate cycle enzymes, malate synthase (MS) and isocitrate lyase (ICL), in animal tissues has been reported. In order to clarify the status of the MS and ICL genes in animals and get an insight into their evolution, we undertook a comparative-genomic study. RESULTS Using sequence similarity searches, we identified MS genes in arthropods, echinoderms, and vertebrates, including platypus and opossum, but not in the numerous sequenced genomes of placental mammals. The regions of the placental mammals' genomes expected to code for malate synthase, as determined by comparison of the gene orders in vertebrate genomes, show clear similarity to the opossum MS sequence but contain stop codons, indicating that the MS gene became a pseudogene in placental mammals. By contrast, the ICL gene is undetectable in animals other than the nematodes that possess a bifunctional, fused ICL-MS gene. Examination of phylogenetic trees of MS and ICL suggests multiple horizontal gene transfer events that probably went in both directions between several bacterial and eukaryotic lineages. The strongest evidence was obtained for the acquisition of the bifunctional ICL-MS gene from an as yet unknown bacterial source with the corresponding operonic organization by the common ancestor of the nematodes. CONCLUSION The distribution of the MS and ICL genes in animals suggests that either they encode alternative enzymes of the glyoxylate cycle that are not orthologous to the known MS and ICL or the animal MS acquired a new function that remains to be characterized. Regardless of the ultimate solution to this conundrum, the genes for the glyoxylate cycle enzymes present a remarkable variety of evolutionary events including unusual horizontal gene transfer from bacteria to animals.
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Affiliation(s)
- Fyodor A Kondrashov
- Section on Ecology, Behavior and Evolution, Division of Biological Sciences, University of California at San Diego, 2218 Muir Biology Building, La Jolla, CA 92093, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Igor G Morgunov
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russian Federation
| | - Tatiana V Finogenova
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russian Federation
| | - Marie N Kondrashova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russian Federation
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Popov VN, Moskalev EA, Shevchenko MU, Eprintsev AT. Comparative Analysis of Glyoxylate Cycle Key Enzyme Isocitrate Lyase from Organisms of Different Systematic Groups. J EVOL BIOCHEM PHYS+ 2005. [DOI: 10.1007/s10893-006-0004-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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12
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Gourley BL, Parker SB, Jones BJ, Zumbrennen KB, Leibold EA. Cytosolic aconitase and ferritin are regulated by iron in Caenorhabditis elegans. J Biol Chem 2003; 278:3227-34. [PMID: 12438312 DOI: 10.1074/jbc.m210333200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Iron regulatory protein-1 (IRP-1) is a cytosolic RNA-binding protein that is a regulator of iron homeostasis in mammalian cells. IRP-1 binds to RNA structures, known as iron-responsive elements, located in the untranslated regions of specific mRNAs, and it regulates the translation or stability of these mRNAs. Iron regulates IRP-1 activity by converting it from an RNA-binding apoprotein into a [4Fe-4S] cluster protein exhibiting aconitase activity. IRP-1 is widely found in prokaryotes and eukaryotes. Here, we report the biochemical characterization and regulation of an IRP-1 homolog in Caenorhabditis elegans (GEI-22/ACO-1). GEI-22/ACO-1 is expressed in the cytosol of cells of the hypodermis and the intestine. Like mammalian IRP-1/aconitases, GEI-22/ACO-1 exhibits aconitase activity and is post-translationally regulated by iron. Although GEI-22/ACO-1 shares striking resemblance to mammalian IRP-1, it fails to bind RNA. This is consistent with the lack of iron-responsive elements in the C. elegans ferritin genes, ftn-1 and ftn-2. While mammalian ferritin H and L mRNAs are translationally regulated by iron, the amounts of C. elegans ftn-1 and ftn-2 mRNAs are increased by iron and decreased by iron chelation. Excess iron did not significantly alter worm development but did shorten their life span. These studies indicated that iron homeostasis in C. elegans shares some similarities with those of vertebrates.
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Affiliation(s)
- Brett L Gourley
- Eccles Program in Human Molecular Biology and Genetics and Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, Utah 84112, USA
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Munir E, Hattori T, Shimada M. Purification and characterization of isocitrate lyase from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose. Arch Biochem Biophys 2002; 399:225-31. [PMID: 11888209 DOI: 10.1006/abbi.2002.2770] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isocitrate lyase (EC 4.1.3.1), a key enzyme in the glyoxylate cycle, was purified 76-fold with 23% yield as an electrophoretically homogeneous protein from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose. The native enzyme has a molecular mass of 186 kDa, consisting of three identical subunits of 60 kDa. The K(m) for DL-isocitrate was found to be 1.6 mM at the optimum pH (7.0). The enzyme required Mg(2+) (K(m) 92 microM) and sulfhydryl compounds for optimal activity. The enzyme activity was strongly inhibited by oxalate and itaconate with a K(i) of 37 and 68 microM, respectively. The inhibition by the glycolysis and tricarboxylic acid cycle intermediates and related compounds suggested that the isocitrate lyase was a regulatory enzyme playing a crucial role in the fungal growth.
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Affiliation(s)
- Erman Munir
- Wood Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan
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Munir E, Hattori T, Shimada M. Purification and characterization of malate synthase from the glucose-grown wood-rotting basidiomycete Fomitopsis palustris. Biosci Biotechnol Biochem 2002; 66:576-81. [PMID: 12005052 DOI: 10.1271/bbb.66.576] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Malate synthase (EC 4.1.3.2), the key enzyme of the glyoxylate cycle, was purified to a homogeneous protein from the wood-rotting basidiomycete Fomitopsis palustris grown on glucose. The purified enzyme, with a molecular mass of 520 kDa, was found to consist of eight 65-kDa subunits, and to have Km of 45 and 2.2 microM for glyoxylate and acetyl-CoA, respectively. The enzyme activity was competitively inhibited by oxalate (K1, 8.5 microM) and glycolate (Ki, 17 microM), and uncompetitively by coenzyme A (Ki, 100 microM). The potent inhibition of the activity by p-chloromercuribenzoate suggests that the enzyme has a sulfhydryl group at the active center. However, the enzyme was inhibited moderately by adenine nucleotides and weakly by some of the metabolic intermediates of glycolysis and tricarboxylic acid cycle. The enzyme was completely inactive in the absence of metal ions and was maximally activated by Mg2+ (Km, 0.4 microM), which also served to significantly prevent enzyme inactivation during storage.
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Affiliation(s)
- Erman Munir
- Wood Research Institute, Kyoto University, Uji, Japan
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Abstract
Recent studies have shown that increased hepatic gluconeogenesis is the predominant contributor to fasting hyperglycemia - the hallmark of type 2 diabetes. Although it has been known for a long time that over-supply of fat is able to stimulate gluconeogenesis both in-vitro and in-vivo, neither the leading substrate nor the mechanism responsible for this phenomenon have been fully identified. Recent observations that the glyoxylate pathway may exist in animals has shed light on this question. The glyoxylate pathway is able to convert fatty acid into glucose but has been thought to be absent in animals. Although further evidence is needed, current available data does suggest a possible mechanism which, by integrating both glucose and lipid metabolism together rather than interpreting them separately, may explain the role of fatty acids in hepatic insulin resistance. This hypothesis is based on current understanding of insulin resistance and supported by many laboratory observations.
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Affiliation(s)
- S Song
- Department of Medicine, University of Melbourne, Australia
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Gragera RR, Martínez-Rodríguez R, Capilla J, De Miguel E, Gómez de Segura I, Turégano L, Alvarez MI, Toledano A. Localization of glyoxylate dehydrogenase and glyoxylate-complex molecules in the rat prefrontal cortex: enzymohistochemical and immunocytochemical study. J Neurosci Res 2000; 59:561-7. [PMID: 10679796 DOI: 10.1002/(sici)1097-4547(20000215)59:4<561::aid-jnr12>3.0.co;2-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Glyoxylic acid is synthesized and catabolized in cells of vertebrates; several pathways have been described. In previous papers, we have demonstrated the localization in some areas of the rat cerebral cortex both of beta-NAD-dependent glyoxylate dehydrogenase (glyoDH), using an enzymohistochemical method, and of glyoxylate-complex molecules, using immunocytochemical procedures. In this study we have applied these two techniques in various areas of the prefrontal cortex with different histological cytoarchitecture. GlyoDH has been located in most neurons, in some glial cells, and in capillary wall structures in all cortical layers of all areas of the rat prefrontal cortex. Antibodies against glyoxylate-complex molecules showed positive immunoreactivity in scattered neurons, mostly of multipolar or stellate appearance, from layers III, IV, and V in the medial precentral area, but not in cortical areas 24, 25, or 32 of the prefrontal cortex. Immunoreaction was found in the periphery of neuronal perikarya and in some of their processes. These results demonstrate the existence of a particular area-dependent neuronal cortical system, of specific but uncertain function, related to glyoxylic acid and/or glyoxylate compounds. At the electron microscope level, positive reaction was associated with synaptic sites, axonal filaments, glial cells, and several components of the blood-brain barrier. These localizations suggest the involvement of glyoxylate derivatives in synaptic functioning and also in glial cell functions.
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Affiliation(s)
- R R Gragera
- Department of Morphological Sciences and Surgery, Faculty of Medicine, Alcalá de Henares University, Alcalá de Henares, Spain
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