The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Stephan Hinderlich - One of the best experts on this subject based on the ideXlab platform.
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Small Molecules Targeting Human N‐Acetylmannosamine Kinase
Chembiochem : a European journal of chemical biology, 2017Co-Authors: Stephan Hinderlich, Long D. Nguyen, Martin Neuenschwander, Paul-robin Wratil, Andreas Oder, Michael Lisurek, Jens Peter Von Kries, Christian P. R. HackenbergerAbstract:N-Acetylmannosamine kinase (MNK) plays a key role in the biosynthesis of sialic acids and glycosylation of proteins. Sialylated glycoconjugates affect a large number of biological processes, including immune modulation and cancer transformation. In search of effective inhibitors of MNK we applied high-throughput screening of drug-like small molecules. By applying different orthogonal assays for their validation we identified four potential MNK-specific inhibitors with IC50 values in the low-micromolar range. Molecular modelling of the inhibitors into the active site of MNK supports their binding to the sugar or the ATP-binding pocket of the enzyme or both. These compounds are promising for downregulation of the sialic acid content of glycoconjugates and for studying the functional contribution of sialic acids to disease development.
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Inhibition of the key enzyme of sialic acid biosynthesis by C6-Se modified N-Acetylmannosamine analogs
Chemical science, 2016Co-Authors: Olaia Nieto-garcia, Stephan Hinderlich, Werner Reutter, Paul R. Wratil, Long D. Nguyen, Verena Böhrsch, Christian P. R. HackenbergerAbstract:Synthetically accessible C6-analogs of N-Acetylmannosamine (ManNAc) were tested as potential inhibitors of the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (GNE/MNK), the key enzyme of sialic acid biosynthesis. Enzymatic experiments revealed that the modification introduced at the C6 saccharide position strongly influences the inhibitory potency. A C6-ManNAc diselenide dimer showed the strongest kinase inhibition in the low μM range among all the substrates tested and successfully reduced cell surface sialylation in Jurkat cells.
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UDP-GlcNAc 2-Epimerase/ManNAc Kinase (GNE): A Master Regulator of Sialic Acid Synthesis.
Topics in Current Chemistry, 2013Co-Authors: Stephan Hinderlich, Tal Yardeni, Rüdiger Horstkorte, Wenke Weidemann, Marjan HuizingAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
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udp glcnac 2 epimerase mannac kinase gne a master regulator of sialic acid synthesis
Topics in Current Chemistry, 2013Co-Authors: Stephan Hinderlich, Tal Yardeni, Rüdiger Horstkorte, Wenke Weidemann, Marjan HuizingAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
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Crystal Structures of N-Acetylmannosamine Kinase Provide Insights into Enzyme Activity and Inhibition
The Journal of biological chemistry, 2012Co-Authors: Jacobo Martinez, Stephan Hinderlich, Werner Reutter, Long Duc Nguyen, Reinhold Zimmer, Eva Tauberger, Wolfram Saenger, Hua Fan, S. MoniotAbstract:Sialic acids are essential components of membrane glycoconjugates. They are responsible for the interaction, structure, and functionality of all deuterostome cells and have major functions in cellular processes in health and diseases. The key enzyme of the biosynthesis of sialic acid is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase that transforms UDP-N-acetylglucosamine to N-Acetylmannosamine (ManNAc) followed by its phosphorylation to ManNAc 6-phosphate and has a direct impact on the sialylation of cell surface components. Here, we present the crystal structures of the human N-Acetylmannosamine kinase (MNK) domain of UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase in complexes with ManNAc at 1.64 Å resolution, MNK·ManNAc·ADP (1.82 Å) and MNK·ManNAc 6-phosphate·ADP (2.10 Å). Our findings offer detailed insights in the active center of MNK and serve as a structural basis to design inhibitors. We synthesized a novel inhibitor, 6-O-acetyl-ManNAc, which is more potent than those previously tested. Specific inhibitors of sialic acid biosynthesis may serve to further study biological functions of sialic acid.
Werner Reutter - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of the key enzyme of sialic acid biosynthesis by C6-Se modified N-Acetylmannosamine analogs
Chemical science, 2016Co-Authors: Olaia Nieto-garcia, Stephan Hinderlich, Werner Reutter, Paul R. Wratil, Long D. Nguyen, Verena Böhrsch, Christian P. R. HackenbergerAbstract:Synthetically accessible C6-analogs of N-Acetylmannosamine (ManNAc) were tested as potential inhibitors of the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (GNE/MNK), the key enzyme of sialic acid biosynthesis. Enzymatic experiments revealed that the modification introduced at the C6 saccharide position strongly influences the inhibitory potency. A C6-ManNAc diselenide dimer showed the strongest kinase inhibition in the low μM range among all the substrates tested and successfully reduced cell surface sialylation in Jurkat cells.
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Fragment-screening of N-Acetylmannosamine kinase reveals non-carbohydrate inhibitors
Canadian Journal of Chemistry, 2016Co-Authors: Jonas Aretz, Werner Reutter, Paul R. Wratil, Eike-christian Wamhoff, Hoang Giang Nguyen, Christoph RademacherAbstract:Many biological processes from infection to tumor immune evasion are controlled by cell surface sialylation. To gather further insight into these processes, methods to alter cell surface sialylation are required. One way to achieve this is inhibiting the key enzyme of sialic acid de novo biosynthesis, the intracellular bifunctional UDP-N-acetylglucosamine epimerase/N-Acetylmannosamine kinase (GNE/MNK). Here, we present low molecular weight inhibitors of MNK activity based on picolinic acid derivatives. They were identified in a fragment screening using 19F NMR and validated in a biochemical inhibition assay followed by a structure–activity relationship analysis and docking. The optimized compound 6-carbamoylpicolinic acid inhibits MNK with a double-digit micromolar affinity. Its low molecular weight (166 Da) renders this picolinic acid derivative an exquisite starting point for the development of high-affinity MNK inhibitors, which may serve as molecular probes or lead candidates in future.
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A novel approach to decrease sialic acid expression in cells by a C-3-modified N-Acetylmannosamine.
The Journal of biological chemistry, 2014Co-Authors: Paul R. Wratil, Werner Reutter, Athanassios Giannis, Stephan Rigol, Barbara Solecka, Guido Kohla, Christoph Kannicht, Long D. NguyenAbstract:Due to its position at the outermost of glycans, sialic acid is involved in a myriad of physiological and pathophysiological cell functions such as host-pathogen interactions, immune regulation, and tumor evasion. Inhibitors of cell surface sialylation could be a useful tool in cancer, immune, antibiotic, or antiviral therapy. In this work, four different C-3 modified N-Acetylmannosamine analogs were tested as potential inhibitors of cell surface sialylation. Peracetylated 2-acetylamino-2-deoxy-3-O-methyl-d-mannose decreases cell surface sialylation in Jurkat cells in a dose-dependent manner up to 80%, quantified by flow cytometry and enzyme-linked lectin assays. High-performance liquid chromatography experiments revealed that not only the concentration of membrane bound but also of cytosolic sialic acid is reduced in treated cells. We have strong evidence that the observed reduction of sialic acid expression in cells is caused by the inhibition of the bifunctional enzyme UDP-GlcNAc-2-epimerase/ManNAc kinase. 2-Acetylamino-2-deoxy-3-O-methyl-d-mannose inhibits the human ManNAc kinase domain of the UDP-GlcNAc-2-epimerase/ManNAc kinase. Binding kinetics of the inhibitor and human N-Acetylmannosamine kinase were evaluated using surface plasmon resonance. Specificity studies with human N-acetylglucosamine kinase and hexokinase IV indicated a high specificity of 2-acetylamino-2-deoxy-3-O-methyl-d-mannose for MNK. This substance represents a novel class of inhibitors of sialic acid expression in cells, targeting the key enzyme of sialic acid de novo biosynthesis.
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Crystal Structures of N-Acetylmannosamine Kinase Provide Insights into Enzyme Activity and Inhibition
The Journal of biological chemistry, 2012Co-Authors: Jacobo Martinez, Stephan Hinderlich, Werner Reutter, Long Duc Nguyen, Reinhold Zimmer, Eva Tauberger, Wolfram Saenger, Hua Fan, S. MoniotAbstract:Sialic acids are essential components of membrane glycoconjugates. They are responsible for the interaction, structure, and functionality of all deuterostome cells and have major functions in cellular processes in health and diseases. The key enzyme of the biosynthesis of sialic acid is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase that transforms UDP-N-acetylglucosamine to N-Acetylmannosamine (ManNAc) followed by its phosphorylation to ManNAc 6-phosphate and has a direct impact on the sialylation of cell surface components. Here, we present the crystal structures of the human N-Acetylmannosamine kinase (MNK) domain of UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase in complexes with ManNAc at 1.64 Å resolution, MNK·ManNAc·ADP (1.82 Å) and MNK·ManNAc 6-phosphate·ADP (2.10 Å). Our findings offer detailed insights in the active center of MNK and serve as a structural basis to design inhibitors. We synthesized a novel inhibitor, 6-O-acetyl-ManNAc, which is more potent than those previously tested. Specific inhibitors of sialic acid biosynthesis may serve to further study biological functions of sialic acid.
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Evidence for Dynamic Interplay of Different Oligomeric States of UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine Kinase by Biophysical Methods
Journal of molecular biology, 2007Co-Authors: Darius Ghaderi, Werner Reutter, Lothar Lucka, Stefan O. Reinke, Holger M. Strauss, Sebahattin Cirak, Stephan HinderlichAbstract:The bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase (GNE) is a key enzyme for the biosynthesis of sialic acids, the terminal sugars of glycoconjugates associated with a variety of physiological and pathological processes such as cell adhesion, development, inflammation and cancer. In this study, we characterized rat GNE by different biophysical methods, analytical ultracentrifugation, dynamic light-scattering and size-exclusion chromatography, all revealing the native hydrodynamic behavior and molar mass of the protein. We show that GNE is able to reversibly self-associate into different oligomeric states including monomers, dimers and tetramers. Additionally, it forms non-specific aggregates of high molecular mass, which cannot be unequivocally assigned a distinct size. Our results also indicate that ligands of the epimerase domain of the bifunctional enzyme, namely UDP-N-acetylglucosamine and CMP-N-acetylneuraminic acid, stabilize the protein against aggregation and are capable of modulating the quaternary structure of the protein. The presence of UDP-N-acetylglucosamine strongly favors the tetrameric state, which therefore likely represents the active state of the enzyme in cells.
Rüdiger Horstkorte - One of the best experts on this subject based on the ideXlab platform.
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UDP-GlcNAc 2-Epimerase/ManNAc Kinase (GNE): A Master Regulator of Sialic Acid Synthesis.
Topics in Current Chemistry, 2013Co-Authors: Stephan Hinderlich, Tal Yardeni, Rüdiger Horstkorte, Wenke Weidemann, Marjan HuizingAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
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udp glcnac 2 epimerase mannac kinase gne a master regulator of sialic acid synthesis
Topics in Current Chemistry, 2013Co-Authors: Stephan Hinderlich, Tal Yardeni, Rüdiger Horstkorte, Wenke Weidemann, Marjan HuizingAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
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Beyond glycosylation: sialic acid precursors act as signaling molecules and are involved in cellular control of differentiation of PC12 cells
Biological chemistry, 2009Co-Authors: Maria Kontou, Wenke Weidemann, Kaya Bork, Rüdiger HorstkorteAbstract:Sialic acids represent a family of 9-carbon acidic amino sugars expressed mainly as terminal monosaccharides on most mammalian glycoconjugates. Sialic acids play an outstanding role during cellular processes, such as development and regeneration, as they are involved in a variety of molecular interactions. Sialic acids are synthesized in the cytosol starting from UDP-N-acetylglucosamine by the UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine-kinase (GNE), which is the key enzyme in the biosynthesis of sialic acid that catalyzes the generation of N-Acetylmannosamine, which in turn is an intermediate of the sialic acid pathway that represents the natural molecular precursor of all sialic acids. Of increasing interest are the influence of the sialic acid precursor N-Acetylmannosamine (or related N-acylmannosamines), GNE, and sialic acids themselves on cellular processes such as proliferation, gene expression, or cell differentiation. Here, we present recent data and review indications that N-acylmannosamines (the direct precursors of all sialic acids) may act as signaling molecules, and that the key enzyme of the sialic acid metabolism is directly involved in the regulation of cell proliferation and cell differentiation.
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Reduced sialylation status in UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (GNE)-deficient mice
Glycoconjugate Journal, 2007Co-Authors: Daniel Gagiannis, Martina Schwarzkopf, Wenke Weidemann, André Orthmann, Ilona Danßmann, Rüdiger HorstkorteAbstract:Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is the bifunctional UDP- N -acetylglucosamine-2-epimerase/ N -acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Previously, we have shown that inactivation of the GNE by gene targeting causes early embryonic lethality in mice, whereas heterozygous GNE-deficient mice are vital. In this study we compared the amount of membrane-bound sialic acids of wildtype mice with those of heterozygous GNE-deficient mice. For that we quantified membrane-bound sialic acid concentration in various organs of wildtype- and heterozygous GNE-deficient mice. We found an organ-specific reduction of membrane-bound sialic acids in heterozygous GNE-deficient mice. The overall reduction was 25%. Additionally, we analyzed transferrin and polysialylated neural cell adhesion molecule (NCAM) by one- or two-dimensional gel electrophoresis. Transferrin-expression was unchanged in heterozygous GNE-deficient mice; however the isoelectric point of transferrin was shifted towards basic pH, indicating a reduced sialylation. Furthermore, the expression of polysialic acids on NCAM was reduced in GNE-deficient mice.
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Reduced sialylation status in UDP- N -acetylglucosamine-2-epimerase/ N -acetylmannosamine kinase (GNE)-deficient mice
Glycoconjugate Journal, 2007Co-Authors: Daniel Gagiannis, Martina Schwarzkopf, Wenke Weidemann, André Orthmann, Ilona Danßmann, Rüdiger HorstkorteAbstract:Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Previously, we have shown that inactivation of the GNE by gene targeting causes early embryonic lethality in mice, whereas heterozygous GNE-deficient mice are vital. In this study we compared the amount of membrane-bound sialic acids of wildtype mice with those of heterozygous GNE-deficient mice. For that we quantified membrane-bound sialic acid concentration in various organs of wildtype- and heterozygous GNE-deficient mice. We found an organ-specific reduction of membrane-bound sialic acids in heterozygous GNE-deficient mice. The overall reduction was 25%. Additionally, we analyzed transferrin and polysialylated neural cell adhesion molecule (NCAM) by one- or two-dimensional gel electrophoresis. Transferrin-expression was unchanged in heterozygous GNE-deficient mice; however the isoelectric point of transferrin was shifted towards basic pH, indicating a reduced sialylation. Furthermore, the expression of polysialic acids on NCAM was reduced in GNE-deficient mice.
Lothar Lucka - One of the best experts on this subject based on the ideXlab platform.
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Efficient metabolic oligosaccharide engineering of glycoproteins by UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase (GNE) knock-down
Molecular bioSystems, 2011Co-Authors: Heinz Möller, Verena Böhrsch, Lothar Lucka, Christian P. R. Hackenberger, Stephan HinderlichAbstract:Improving the accessibility and functions of therapeutic and diagnostic glycoproteins is one of the major goals of glycobiotechnology. Here we present that stable knock-down of UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase (GNE), the key enzyme in the sialic acid biosynthetic pathway, dramatically increases incorporation of N-Acetylmannosamine analogues into glycoproteins of HEK293 cells. By means of these GNE-deficient cells highly sialylated glycoproteins can efficiently be decorated with reactive functional groups, which can be employed in bioorthogonal functionalization strategies for fluorescence labelling or biotinylation.
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Evidence for Dynamic Interplay of Different Oligomeric States of UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine Kinase by Biophysical Methods
Journal of molecular biology, 2007Co-Authors: Darius Ghaderi, Werner Reutter, Lothar Lucka, Stefan O. Reinke, Holger M. Strauss, Sebahattin Cirak, Stephan HinderlichAbstract:The bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase (GNE) is a key enzyme for the biosynthesis of sialic acids, the terminal sugars of glycoconjugates associated with a variety of physiological and pathological processes such as cell adhesion, development, inflammation and cancer. In this study, we characterized rat GNE by different biophysical methods, analytical ultracentrifugation, dynamic light-scattering and size-exclusion chromatography, all revealing the native hydrodynamic behavior and molar mass of the protein. We show that GNE is able to reversibly self-associate into different oligomeric states including monomers, dimers and tetramers. Additionally, it forms non-specific aggregates of high molecular mass, which cannot be unequivocally assigned a distinct size. Our results also indicate that ligands of the epimerase domain of the bifunctional enzyme, namely UDP-N-acetylglucosamine and CMP-N-acetylneuraminic acid, stabilize the protein against aggregation and are capable of modulating the quaternary structure of the protein. The presence of UDP-N-acetylglucosamine strongly favors the tetrameric state, which therefore likely represents the active state of the enzyme in cells.
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Domain-specific characteristics of the bifunctional key enzyme of sialic acid biosynthesis, UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
Biochemical Journal, 2004Co-Authors: Astrid Blume, Werner Reutter, Rüdiger Horstkorte, Lothar Lucka, Wenke Weidemann, Ulrich Stelzl, Erich E. Wanker, Peter Donner, Stephan HinderlichAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is a bifunctional enzyme, which initiates and regulates sialic acid biosynthesis. Sialic acids are important compounds of mammalian glycoconjugates, mediating several biological processes, such as cell-cell or cell-matrix interactions. In order to characterize the function of UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase, a number of deletion mutants were generated, lacking either parts of the N-terminal epimerase or the C-terminal kinase domain. N-terminal deletion of only 39 amino acids results in a complete loss of epimerase activity. Deletions in the C-terminal part result in a reduction or complete loss of kinase activity, depending on the size of the deletion. Deletions at either the N- or the C-terminus also result in a reduction of the other enzyme activity. These results indicate that a separate expression of both domains is possible, but that a strong intramolecular dependency of the two domains has arisen during evolution of the enzyme. N-terminal, as well as C-terminal, mutants tend to form trimers, in addition to the hexameric structure of the native enzyme. These results and yeast two-hybrid experiments show that structures required for dimerization are localized within the kinase domain, and a potential trimerization site is possibly located in a region between the two domains. In conclusion, our results reveal that the activities, as well as the oligomeric structure, of this bifunctional enzyme seem to be organized and regulated in a complex manner.
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Protein kinase C phosphorylates and regulates UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase.
FEBS Letters, 2000Co-Authors: Rüdiger Horstkorte, Werner Reutter, Karin Effertz, Sabine Nöhring, Kerstin Danker, Lothar LuckaAbstract:UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (UDP-GlcNAc 2-epimerase) is the key enzyme in the de novo synthesis pathway of neuraminic acid, which is widely expressed as a terminal carbohydrate residue on glycoconjugates. UDP-GlcNAc 2-epimerase is a bifunctional enzyme and catalyzes the first two steps of neuraminic acid synthesis in the cytosol, the conversion of UDP-N-acetylglucosamine to ManAc and the phosphorylation to ManAc-6-phosphate. So far, regulation of this essential enzyme by posttranslational modification has not been shown. Since UDP-N-acetylglucosamine is a cytosolic protein containing eight conserved motifs for protein kinase C (PKC), we investigated whether its enzymatic activity might be regulated by phosphorylation by PKC. We showed that UDP-GlcNAc 2-epimerase interacts with several isoforms of PKC in mouse liver and is phosphorylated in vivo. Furthermore, PKC phosphorylates UDP-GlcNAc 2-epimerase and this phosphorylation results in an upregulation of the UDP-GlcNAc 2-epimerase enzyme activity.
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primary structure and expression analysis of human udp n acetyl glucosamine 2 epimerase n acetylmannosamine kinase the bifunctional enzyme in neuraminic acid biosynthesis
FEBS Letters, 1999Co-Authors: Lothar Lucka, Werner Reutter, Kerstin Danker, Matthias Krause, Rüdiger HorstkorteAbstract:N-Acetylneuraminic acid is a main constituent of glycoproteins and gangliosides. In many membrane-bound receptors it is the target for external stimuli. The key enzyme for its biosynthesis is the bifunctional enzyme UDP-N-acetyl-glucosamine-2-epimerase/N-Acetylmannosamine kinase, catalysing the first two steps of the biosynthesis in the cytosol. The rat enzyme was previously isolated and characterised. In this report we present the corresponding human cDNA sequence, compare it with the primary structure of the rodent enzyme, and report the analysis of its expression in different human tissues and cell lines.
Wenke Weidemann - One of the best experts on this subject based on the ideXlab platform.
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UDP-GlcNAc 2-Epimerase/ManNAc Kinase (GNE): A Master Regulator of Sialic Acid Synthesis.
Topics in Current Chemistry, 2013Co-Authors: Stephan Hinderlich, Tal Yardeni, Rüdiger Horstkorte, Wenke Weidemann, Marjan HuizingAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
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udp glcnac 2 epimerase mannac kinase gne a master regulator of sialic acid synthesis
Topics in Current Chemistry, 2013Co-Authors: Stephan Hinderlich, Tal Yardeni, Rüdiger Horstkorte, Wenke Weidemann, Marjan HuizingAbstract:UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase.
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Beyond glycosylation: sialic acid precursors act as signaling molecules and are involved in cellular control of differentiation of PC12 cells
Biological chemistry, 2009Co-Authors: Maria Kontou, Wenke Weidemann, Kaya Bork, Rüdiger HorstkorteAbstract:Sialic acids represent a family of 9-carbon acidic amino sugars expressed mainly as terminal monosaccharides on most mammalian glycoconjugates. Sialic acids play an outstanding role during cellular processes, such as development and regeneration, as they are involved in a variety of molecular interactions. Sialic acids are synthesized in the cytosol starting from UDP-N-acetylglucosamine by the UDP-N-acetylglucosamine 2-epimerase/N-Acetylmannosamine-kinase (GNE), which is the key enzyme in the biosynthesis of sialic acid that catalyzes the generation of N-Acetylmannosamine, which in turn is an intermediate of the sialic acid pathway that represents the natural molecular precursor of all sialic acids. Of increasing interest are the influence of the sialic acid precursor N-Acetylmannosamine (or related N-acylmannosamines), GNE, and sialic acids themselves on cellular processes such as proliferation, gene expression, or cell differentiation. Here, we present recent data and review indications that N-acylmannosamines (the direct precursors of all sialic acids) may act as signaling molecules, and that the key enzyme of the sialic acid metabolism is directly involved in the regulation of cell proliferation and cell differentiation.
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Reduced sialylation status in UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (GNE)-deficient mice
Glycoconjugate Journal, 2007Co-Authors: Daniel Gagiannis, Martina Schwarzkopf, Wenke Weidemann, André Orthmann, Ilona Danßmann, Rüdiger HorstkorteAbstract:Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is the bifunctional UDP- N -acetylglucosamine-2-epimerase/ N -acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Previously, we have shown that inactivation of the GNE by gene targeting causes early embryonic lethality in mice, whereas heterozygous GNE-deficient mice are vital. In this study we compared the amount of membrane-bound sialic acids of wildtype mice with those of heterozygous GNE-deficient mice. For that we quantified membrane-bound sialic acid concentration in various organs of wildtype- and heterozygous GNE-deficient mice. We found an organ-specific reduction of membrane-bound sialic acids in heterozygous GNE-deficient mice. The overall reduction was 25%. Additionally, we analyzed transferrin and polysialylated neural cell adhesion molecule (NCAM) by one- or two-dimensional gel electrophoresis. Transferrin-expression was unchanged in heterozygous GNE-deficient mice; however the isoelectric point of transferrin was shifted towards basic pH, indicating a reduced sialylation. Furthermore, the expression of polysialic acids on NCAM was reduced in GNE-deficient mice.
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Reduced sialylation status in UDP- N -acetylglucosamine-2-epimerase/ N -acetylmannosamine kinase (GNE)-deficient mice
Glycoconjugate Journal, 2007Co-Authors: Daniel Gagiannis, Martina Schwarzkopf, Wenke Weidemann, André Orthmann, Ilona Danßmann, Rüdiger HorstkorteAbstract:Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-Acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Previously, we have shown that inactivation of the GNE by gene targeting causes early embryonic lethality in mice, whereas heterozygous GNE-deficient mice are vital. In this study we compared the amount of membrane-bound sialic acids of wildtype mice with those of heterozygous GNE-deficient mice. For that we quantified membrane-bound sialic acid concentration in various organs of wildtype- and heterozygous GNE-deficient mice. We found an organ-specific reduction of membrane-bound sialic acids in heterozygous GNE-deficient mice. The overall reduction was 25%. Additionally, we analyzed transferrin and polysialylated neural cell adhesion molecule (NCAM) by one- or two-dimensional gel electrophoresis. Transferrin-expression was unchanged in heterozygous GNE-deficient mice; however the isoelectric point of transferrin was shifted towards basic pH, indicating a reduced sialylation. Furthermore, the expression of polysialic acids on NCAM was reduced in GNE-deficient mice.
