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Yang HC, Wu YH, Yen WC, Liu HY, Hwang TL, Stern A, Chiu DTY. The Redox Role of G6PD in Cell Growth, Cell Death, and Cancer. Cells 2019; 8:cells8091055. [PMID: 31500396 PMCID: PMC6770671 DOI: 10.3390/cells8091055] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 09/02/2019] [Accepted: 09/07/2019] [Indexed: 02/07/2023] Open
Abstract
The generation of reducing equivalent NADPH via glucose-6-phosphate dehydrogenase (G6PD) is critical for the maintenance of redox homeostasis and reductive biosynthesis in cells. NADPH also plays key roles in cellular processes mediated by redox signaling. Insufficient G6PD activity predisposes cells to growth retardation and demise. Severely lacking G6PD impairs embryonic development and delays organismal growth. Altered G6PD activity is associated with pathophysiology, such as autophagy, insulin resistance, infection, inflammation, as well as diabetes and hypertension. Aberrant activation of G6PD leads to enhanced cell proliferation and adaptation in many types of cancers. The present review aims to update the existing knowledge concerning G6PD and emphasizes how G6PD modulates redox signaling and affects cell survival and demise, particularly in diseases such as cancer. Exploiting G6PD as a potential drug target against cancer is also discussed.
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Affiliation(s)
- Hung-Chi Yang
- Department of Medical Laboratory Science and Biotechnology, Yuanpei University of Medical Technology, Hsinchu, Taiwan.
| | - Yi-Hsuan Wu
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan.
| | - Wei-Chen Yen
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
- Department of Medical Biotechnology and Laboratory Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
| | - Hui-Ya Liu
- Department of Medical Biotechnology and Laboratory Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
| | - Tsong-Long Hwang
- Research Center for Food and Cosmetic Safety, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan.
- Graduate Institute of Natural Products, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
- Chinese Herbal Medicine Research Team, Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan.
- Department of Anaesthesiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
- Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City, Taiwan.
- Research Center for Chinese Herbal Medicine, Graduate Institute of Health Industry Technology, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan.
| | - Arnold Stern
- New York University School of Medicine, New York, NY, USA.
| | - Daniel Tsun-Yee Chiu
- Department of Medical Biotechnology and Laboratory Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
- Research Center for Chinese Herbal Medicine, Graduate Institute of Health Industry Technology, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan.
- Department of Pediatric Hematology/Oncology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
- Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan.
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Haeussler K, Berneburg I, Jortzik E, Hahn J, Rahbari M, Schulz N, Preuss J, Zapol'skii VA, Bode L, Pinkerton AB, Kaufmann DE, Rahlfs S, Becker K. Glucose 6-phosphate dehydrogenase 6-phosphogluconolactonase: characterization of the Plasmodium vivax enzyme and inhibitor studies. Malar J 2019; 18:22. [PMID: 30683097 PMCID: PMC6346587 DOI: 10.1186/s12936-019-2651-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 01/16/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Since malaria parasites highly depend on ribose 5-phosphate for DNA and RNA synthesis and on NADPH as a source of reducing equivalents, the pentose phosphate pathway (PPP) is considered an excellent anti-malarial drug target. In Plasmodium, a bifunctional enzyme named glucose 6-phosphate dehydrogenase 6-phosphogluconolactonase (GluPho) catalyzes the first two steps of the PPP. PfGluPho has been shown to be essential for the growth of blood stage Plasmodium falciparum parasites. METHODS Plasmodium vivax glucose 6-phosphate dehydrogenase (PvG6PD) was cloned, recombinantly produced in Escherichia coli, purified, and characterized via enzyme kinetics and inhibitor studies. The effects of post-translational cysteine modifications were assessed via western blotting and enzyme activity assays. Genetically encoded probes were employed to study the effects of G6PD inhibitors on the cytosolic redox potential of Plasmodium. RESULTS Here the recombinant production and characterization of PvG6PD, the C-terminal and NADPH-producing part of PvGluPho, is described. A comparison with PfG6PD (the NADPH-producing part of PfGluPho) indicates that the P. vivax enzyme has higher KM values for the substrate and cofactor. Like the P. falciparum enzyme, PvG6PD is hardly affected by S-glutathionylation and moderately by S-nitrosation. Since there are several naturally occurring variants of PfGluPho, the impact of these mutations on the kinetic properties of the enzyme was analysed. Notably, in contrast to many human G6PD variants, the mutations resulted in only minor changes in enzyme activity. Moreover, nanomolar IC50 values of several compounds were determined on P. vivax G6PD (including ellagic acid, flavellagic acid, and coruleoellagic acid), inhibitors that had been previously characterized on PfGluPho. ML304, a recently developed PfGluPho inhibitor, was verified to also be active on PvG6PD. Using genetically encoded probes, ML304 was confirmed to disturb the cytosolic glutathione-dependent redox potential of P. falciparum blood stage parasites. Finally, a new series of novel small molecules with the potential to inhibit the falciparum and vivax enzymes were synthesized, resulting in two compounds with nanomolar activity. CONCLUSION The characterization of PvG6PD makes this enzyme accessible to further drug discovery activities. In contrast to naturally occurring G6PD variants in the human host that can alter the kinetic properties of the enzyme and thus the redox homeostasis of the cells, the naturally occurring PfGluPho variants studied here are unlikely to have a major impact on the parasites' redox homeostasis. Several classes of inhibitors have been successfully tested and are presently being followed up.
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Affiliation(s)
- Kristina Haeussler
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Isabell Berneburg
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Esther Jortzik
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Julia Hahn
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Mahsa Rahbari
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Norma Schulz
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Janina Preuss
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany.,Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA.,Department of Pediatrics, University of California San Diego, San Diego, CA, 92093, USA
| | - Viktor A Zapol'skii
- Institute of Organic Chemistry, Clausthal University of Technology, 38678, Clausthal-Zellerfeld, Germany
| | - Lars Bode
- Department of Pediatrics, University of California San Diego, San Diego, CA, 92093, USA
| | - Anthony B Pinkerton
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Dieter E Kaufmann
- Institute of Organic Chemistry, Clausthal University of Technology, 38678, Clausthal-Zellerfeld, Germany
| | - Stefan Rahlfs
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Katja Becker
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany.
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Hallé F, Fin A, Rovira AR, Tor Y. Emissive Synthetic Cofactors: Enzymatic Interconversions of tz A Analogues of ATP, NAD + , NADH, NADP + , and NADPH. Angew Chem Int Ed Engl 2018; 57:1087-1090. [PMID: 29228460 PMCID: PMC5771816 DOI: 10.1002/anie.201711935] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Indexed: 12/11/2022]
Abstract
A series of enzymatic transformations, which generate visibly emissive isofunctional cofactors based on an isothiazolo[4,3-d]pyrimidine analogue of adenosine (tz A), was developed. Nicotinamide adenylyl transferase condenses nicotinamide mononucleotide and tz ATP to yield Ntz AD+ , which can be enzymatically phosphorylated by NAD+ kinase and ATP or tz ATP to the corresponding Ntz ADP+ . The latter can be engaged in NADP-specific coupled enzymatic transformations involving conversion to Ntz ADPH by glucose-6-phosphate dehydrogenase and reoxidation to Ntz ADP+ by glutathione reductase. The Ntz ADP+ /Ntz ADPH cycle can be monitored in real time by fluorescence spectroscopy.
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Affiliation(s)
- François Hallé
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0358, USA
| | - Andrea Fin
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0358, USA
| | - Alexander R Rovira
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0358, USA
| | - Yitzhak Tor
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0358, USA
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4
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Emissive Synthetic Cofactors: Enzymatic Interconversions of tz
A Analogues of ATP, NAD+
, NADH, NADP+
, and NADPH. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201711935] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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5
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Zou W, Al-Rubeai M. Understanding central carbon metabolism of rapidly proliferating mammalian cells based on analysis of key enzymatic activities in GS-CHO cell lines. Biotechnol Appl Biochem 2016; 63:642-651. [PMID: 26108557 DOI: 10.1002/bab.1409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 06/19/2015] [Indexed: 12/20/2022]
Abstract
The central carbon metabolism (glycolysis, the pentose phosphate pathway [PPP], and the tricarboxylic acid [TCA] cycle) plays an essential role in the supply of biosynthetic precursors and energy. How the central carbon metabolism changes with the varying growth rates in the in vitro cultivation of rapidly proliferating mammalian cells, such as cancer cells and continuous cell lines for recombinant protein production, remains elusive. Based on relationships between the growth rate and the activity of seven key enzymes from six cell clones, this work reports finding an important metabolic characteristic in rapidly proliferating glutamine synthetase-Chinese hamster ovary cells. The key enzymatic activity involved in the TCA cycle that is responsible for the supply of energy became elevated as the growth rate exhibited increases, while the activity of key enzymes in metabolic pathways (glycolysis and the PPP), responsible for the supply of biosynthetic precursors, tended to decrease-suggesting that rapidly proliferating cells still depended predominantly on the TCA cycle rather than on aerobic glycolysis for their energetic demands. Meanwhile, the growth-limiting resource was most likely biosynthetic substrates rather than energy provision. In addition, the multifaceted role of glucose-6-phosphate isomerase (PGI) was confirmed, based on a significant correlation between PGI activity and the percentage of G2/M-phase cells.
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Affiliation(s)
- Wu Zou
- School of Chemical and Bioprocess Engineering, and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, Ireland
| | - Mohamed Al-Rubeai
- School of Chemical and Bioprocess Engineering, and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, Ireland.
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Yang HC, Wu YH, Liu HY, Stern A, Chiu DTY. What has passed is prolog: new cellular and physiological roles of G6PD. Free Radic Res 2016; 50:1047-1064. [PMID: 27684214 DOI: 10.1080/10715762.2016.1223296] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
G6PD deficiency has been the most pervasive inherited disorder in the world since having been discovered. G6PD has an antioxidant role by functioning as a major nicotinamide adenine dinucleotide phosphate (NADPH) provider to reduce excessive oxidative stress. NADPH can produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) mediated by NADPH oxidase (NOX) and nitric oxide synthase (NOS), respectively. Hence, G6PD also has a pro-oxidant role. Research in the past has focused on the enhanced susceptibility of G6PD-deficient cells or individuals to oxidative challenge. The cytoregulatory role of G6PD has largely been overlooked. By using a metabolomic approach, it is noted that upon oxidant challenge, G6PD-deficient cells will reprogram the GSH metabolism from regeneration to synthesis with exhaustive energy consumption. Recently, new cellular/physiologic roles of G6PD have been discovered. By using a proteomic approach, it has been found that G6PD plays a regulatory role in xenobiotic metabolism possibly via NOX and the redox-sensitive Nrf2-signaling pathway to modulate the expression of xenobiotic-metabolizing enzymes. Since G6PD is a key regulator responsible for intracellular redox homeostasis, G6PD deficiency can alter redox balance leading to many abnormal cellular effects such as the cellular inflammatory and immune response against viral infection. G6PD may play an important role in embryogenesis as G6PD-knockdown mouse cannot produce offspring and G6PD-deficient C. elegans with defective egg production and hatching. This array of findings indicates that the cellular and physiologic roles of G6PD, other than the classical role as an antioxidant enzyme, deserve further attention.
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Affiliation(s)
- Hung-Chi Yang
- a Department of Medical Biotechnology and Laboratory Sciences , College of Medicine, Chang Gung University , Taoyuan , Taiwan.,b Healthy Aging Research Center, Chang Gung University , Taoyuan , Taiwan
| | - Yi-Hsuan Wu
- a Department of Medical Biotechnology and Laboratory Sciences , College of Medicine, Chang Gung University , Taoyuan , Taiwan
| | - Hui-Ya Liu
- a Department of Medical Biotechnology and Laboratory Sciences , College of Medicine, Chang Gung University , Taoyuan , Taiwan
| | - Arnold Stern
- c Department of Biochemistry and Molecular Pharmacology , New York University School of Medicine , New York , NY , USA
| | - Daniel Tsun-Yee Chiu
- a Department of Medical Biotechnology and Laboratory Sciences , College of Medicine, Chang Gung University , Taoyuan , Taiwan.,b Healthy Aging Research Center, Chang Gung University , Taoyuan , Taiwan.,d Department of Pediatric Hematology/Oncology , Chang Gung Memorial Hospital , Linkou , Taiwan
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Kuehne A, Emmert H, Soehle J, Winnefeld M, Fischer F, Wenck H, Gallinat S, Terstegen L, Lucius R, Hildebrand J, Zamboni N. Acute Activation of Oxidative Pentose Phosphate Pathway as First-Line Response to Oxidative Stress in Human Skin Cells. Mol Cell 2015; 59:359-71. [PMID: 26190262 DOI: 10.1016/j.molcel.2015.06.017] [Citation(s) in RCA: 260] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 05/12/2015] [Accepted: 06/10/2015] [Indexed: 12/18/2022]
Abstract
Integrity of human skin is endangered by exposure to UV irradiation and chemical stressors, which can provoke a toxic production of reactive oxygen species (ROS) and oxidative damage. Since oxidation of proteins and metabolites occurs virtually instantaneously, immediate cellular countermeasures are pivotal to mitigate the negative implications of acute oxidative stress. We investigated the short-term metabolic response in human skin fibroblasts and keratinocytes to H2O2 and UV exposure. In time-resolved metabolomics experiments, we observed that within seconds after stress induction, glucose catabolism is routed to the oxidative pentose phosphate pathway (PPP) and nucleotide synthesis independent of previously postulated blocks in glycolysis (i.e., of GAPDH or PKM2). Through ultra-short (13)C labeling experiments, we provide evidence for multiple cycling of carbon backbones in the oxidative PPP, potentially maximizing NADPH reduction. The identified metabolic rerouting in oxidative and non-oxidative PPP has important physiological roles in stabilization of the redox balance and ROS clearance.
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Affiliation(s)
- Andreas Kuehne
- Institute of Molecular Systems Biology, ETH Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, Switzerland; PhD Program Systems Biology, Life Science Zurich Graduate School, 8093 Zurich, Switzerland
| | - Hila Emmert
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Joern Soehle
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Marc Winnefeld
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Frank Fischer
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Horst Wenck
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Stefan Gallinat
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Lara Terstegen
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany
| | - Ralph Lucius
- Christian Albrecht University Kiel, Department of Anatomy, Otto-Hahn-Platz 8, 24118 Kiel, Germany
| | - Janosch Hildebrand
- Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg, 20253 Germany.
| | - Nicola Zamboni
- Institute of Molecular Systems Biology, ETH Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, Switzerland.
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8
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Maier K, Hofmann U, Reuss M, Mauch K. Dynamics and control of the central carbon metabolism in hepatoma cells. BMC SYSTEMS BIOLOGY 2010; 4:54. [PMID: 20426867 PMCID: PMC2874527 DOI: 10.1186/1752-0509-4-54] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 04/28/2010] [Indexed: 02/08/2023]
Abstract
BACKGROUND The liver plays a major role in metabolism and performs a number of vital functions in the body. Therefore, the determination of hepatic metabolite dynamics and the analysis of the control of the respective biochemical pathways are of great pharmacological and medical importance. Extra- and intracellular time-series data from stimulus-response experiments are gaining in importance in the identification of in vivo metabolite dynamics, while dynamic network models are excellent tools for analyzing complex metabolic control patterns. This is the first study that has been undertaken on the data-driven identification of a dynamic liver central carbon metabolism model and its application in the analysis of the distribution of metabolic control in hepatoma cells. RESULTS Dynamic metabolite data were collected from HepG2 cells after they had been deprived of extracellular glucose. The concentration of 25 extra- and intracellular intermediates was quantified using HPLC, LC-MS-MS, and GC-MS. The in silico metabolite dynamics were in accordance with the experimental data. The central carbon metabolism of hepatomas was further analyzed with a particular focus on the control of metabolite concentrations and metabolic fluxes. It was observed that the enzyme glucose-6-phosphate dehydrogenase exerted substantial negative control over the glycolytic flux, whereas oxidative phosphorylation had a significant positive control. The control over the rate of NADPH consumption was found to be shared between the NADPH-demand itself (0.65) and the NADPH supply (0.38). CONCLUSIONS Based on time-series data, a dynamic central carbon metabolism model was developed for the investigation of new and complex metabolic control patterns in hepatoma cells. The control patterns found support the hypotheses that the glucose-6-phosphate dehydrogenase and the Warburg effect are promising targets for tumor treatment. The systems-oriented identification of metabolite dynamics is a first step towards the genome-based assessment of potential risks posed by nutrients and drugs.
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Affiliation(s)
- Klaus Maier
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Ute Hofmann
- Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart and University of Tuebingen, Auerbachstrasse 112, 70376 Stuttgart, Germany
| | - Matthias Reuss
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Klaus Mauch
- Insilico Biotechnology AG, Nobelstrasse 15, 70569 Stuttgart, Germany
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Karatas-Wulf U, Koepsell H, Bergert M, Sönnekes S, Kugler P. Protein kinase C–dependent trafficking of glutamate transporters excitatory amino acid carrier 1 and glutamate transporter 1b in cultured cerebellar granule cells. Neuroscience 2009; 161:794-805. [DOI: 10.1016/j.neuroscience.2009.04.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 04/07/2009] [Accepted: 04/07/2009] [Indexed: 10/20/2022]
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10
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Ninfali P, Ditroilo M, Capellacci S, Biagiotti E. Rabbit brain glucose-6-phosphate dehydrogenase: biochemical properties and inactivation by free radicals and 4-hydroxy-2-nonenal. Neuroreport 2001; 12:4149-53. [PMID: 11742255 DOI: 10.1097/00001756-200112210-00057] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) purified from rabbit brain is composed of two identical subunits of 56 kDa. The enzyme exhibits biphasic pH curve, linear Arrhenius plot and elevated susceptibility to inactivation by metal catalyzed oxidation and thiol binding reagents. 4-Hydroxy-2-nonenal (HNE) is able to inactivate the enzyme after only a few minutes of incubation. Since reactive oxygen species and G6PD-HNE adducts form easily in brain under conditions of oxidative stress, these findings have important implications in the loss of active G6PD molecules in vivo, a process which lowers the antioxidant protection and may be critical for neuron survival.
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Affiliation(s)
- P Ninfali
- Istituto di Chimica Biologica G. Fornaini, Via Saffi 2, 61029 Urbino (PU) Italy
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11
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Kugler P. Glucose-6-phosphate dehydrogenase is enriched in oligodendrocytes of the rat spinal cord. Enzyme histochemical and immunocytochemical studies. HISTOCHEMISTRY 1994; 101:143-53. [PMID: 8071087 DOI: 10.1007/bf00269361] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) was localized in rat spinal cord by catalytic enzyme histochemistry and immunocytochemistry. G6PD detected by either method was shown to be strongly enriched in cell bodies and processes of oligodendrocytes, whereas in the compact myelin G6PD was not detected. The enzyme histochemical procedure for the demonstration of G6PD was also adapted for microphotometric measurements of G6PD activity in the spinal cord white matter. There was a linear relationship between G6PD activity and section thickness up to 14 microns and between G6PD activity and reaction time up to 5-6 min as demonstrated by kinetic and end-point measurements. Significantly lower activities were measured in end-point measurements than in kinetic measurements because of formazan loss during rinsing. Methoxyphenazine methosulphate as an exogenous electron carrier and sodium azide as a blocker of the respiratory chain significantly increased the demonstrable G6PD activity. The Km was 0.62 mM and the Vmax 3 mumol glucose-6-phosphate/cm3 wet tissue and per min at 25 degrees C. It is concluded that G6PD in oligodendrocytes may be important for the generation of NADPH required for lipid biosynthesis related to myelogenesis, and reduction of glutathione required for protection of membrane sulphydryl groups.
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Affiliation(s)
- P Kugler
- Institute of Anatomy, University of Würzburg, Germany
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12
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Joshi JG, Clauberg M, Dhar MS. Role of Aluminum and Iron in Brain Disorders. ADVANCES IN BEHAVIORAL BIOLOGY 1992. [DOI: 10.1007/978-1-4615-3432-7_28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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