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Abu Aqel Y, Alnesf A, Aigha II, Islam Z, Kolatkar PR, Teo A, Abdelalim EM. Glucokinase (GCK) in diabetes: from molecular mechanisms to disease pathogenesis. Cell Mol Biol Lett 2024; 29:120. [PMID: 39245718 PMCID: PMC11382428 DOI: 10.1186/s11658-024-00640-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 08/23/2024] [Indexed: 09/10/2024] Open
Abstract
Glucokinase (GCK), a key enzyme in glucose metabolism, plays a central role in glucose sensing and insulin secretion in pancreatic β-cells, as well as glycogen synthesis in the liver. Mutations in the GCK gene have been associated with various monogenic diabetes (MD) disorders, including permanent neonatal diabetes mellitus (PNDM) and maturity-onset diabetes of the young (MODY), highlighting its importance in maintaining glucose homeostasis. Additionally, GCK gain-of-function mutations lead to a rare congenital form of hyperinsulinism known as hyperinsulinemic hypoglycemia (HH), characterized by increased enzymatic activity and increased glucose sensitivity in pancreatic β-cells. This review offers a comprehensive exploration of the critical role played by the GCK gene in diabetes development, shedding light on its expression patterns, regulatory mechanisms, and diverse forms of associated monogenic disorders. Structural and mechanistic insights into GCK's involvement in glucose metabolism are discussed, emphasizing its significance in insulin secretion and glycogen synthesis. Animal models have provided valuable insights into the physiological consequences of GCK mutations, although challenges remain in accurately recapitulating human disease phenotypes. In addition, the potential of human pluripotent stem cell (hPSC) technology in overcoming current model limitations is discussed, offering a promising avenue for studying GCK-related diseases at the molecular level. Ultimately, a deeper understanding of GCK's multifaceted role in glucose metabolism and its dysregulation in disease states holds implications for developing targeted therapeutic interventions for diabetes and related disorders.
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Affiliation(s)
- Yasmin Abu Aqel
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar
| | - Aldana Alnesf
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Education City, Doha, Qatar
| | - Idil I Aigha
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar
| | - Zeyaul Islam
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), PO Box 34110, Doha, Qatar
| | - Prasanna R Kolatkar
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Education City, Doha, Qatar
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), PO Box 34110, Doha, Qatar
| | - Adrian Teo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Proteos, Singapore, Singapore
- Department of Biochemistry and Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Precision Medicine Translational Research Programme (PM TRP), Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Essam M Abdelalim
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar.
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Education City, Doha, Qatar.
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Berger C, Zdzieblo D. Glucose transporters in pancreatic islets. Pflugers Arch 2020; 472:1249-1272. [PMID: 32394191 PMCID: PMC7462922 DOI: 10.1007/s00424-020-02383-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 02/07/2023]
Abstract
The fine-tuning of glucose uptake mechanisms is rendered by various glucose transporters with distinct transport characteristics. In the pancreatic islet, facilitative diffusion glucose transporters (GLUTs), and sodium-glucose cotransporters (SGLTs) contribute to glucose uptake and represent important components in the glucose-stimulated hormone release from endocrine cells, therefore playing a crucial role in blood glucose homeostasis. This review summarizes the current knowledge about cell type-specific expression profiles as well as proven and putative functions of distinct GLUT and SGLT family members in the human and rodent pancreatic islet and further discusses their possible involvement in onset and progression of diabetes mellitus. In context of GLUTs, we focus on GLUT2, characterizing the main glucose transporter in insulin-secreting β-cells in rodents. In addition, we discuss recent data proposing that other GLUT family members, namely GLUT1 and GLUT3, render this task in humans. Finally, we summarize latest information about SGLT1 and SGLT2 as representatives of the SGLT family that have been reported to be expressed predominantly in the α-cell population with a suggested functional role in the regulation of glucagon release.
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Affiliation(s)
- Constantin Berger
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070, Würzburg, Germany
| | - Daniela Zdzieblo
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070, Würzburg, Germany.
- Fraunhofer Institute for Silicate Research (ISC), Translational Center Regenerative Therapies, Neunerplatz 2, 97082, Würzburg, Germany.
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3
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Zhang Y, Hess H. Enhanced Diffusion of Catalytically Active Enzymes. ACS CENTRAL SCIENCE 2019; 5:939-948. [PMID: 31263753 PMCID: PMC6598160 DOI: 10.1021/acscentsci.9b00228] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Indexed: 05/03/2023]
Abstract
The past decade has seen an increasing number of investigations into enhanced diffusion of catalytically active enzymes. These studies suggested that enzymes are actively propelled as they catalyze reactions or bind with ligands (e.g., substrates or inhibitors). In this Outlook, we chronologically summarize and discuss the experimental observations and theoretical interpretations and emphasize the potential contradictions in these efforts. We point out that the existing multimeric forms of enzymes or isozymes may cause artifacts in measurements and that the conformational changes upon substrate binding are usually not sufficient to give rise to a diffusion enhancement greater than 30%. Therefore, more rigorous experiments and a more comprehensive theory are urgently needed to quantitatively validate and describe the enhanced enzyme diffusion.
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Affiliation(s)
- Yifei Zhang
- Department of Biomedical Engineering, Columbia University, 351L Engineering Terrace, 1210 Amsterdam Avenue, New York, New York 10027, United States
| | - Henry Hess
- Department of Biomedical Engineering, Columbia University, 351L Engineering Terrace, 1210 Amsterdam Avenue, New York, New York 10027, United States
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Sekera ER, Wood TD. Sequencing Proteins from Bottom to Top: Combining Techniques for Full Sequence Analysis of Glucokinase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:111-119. [DOI: 10.1007/978-3-030-15950-4_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Allostery is a ubiquitous biological regulatory process in which distant binding sites within a protein or enzyme are functionally and thermodynamically coupled. Allosteric interactions play essential roles in many enzymological mechanisms, often facilitating formation of enzyme-substrate complexes and/or product release. Thus, elucidating the forces that drive allostery is critical to understanding the complex transformations of biomolecules. Currently, a number of models exist to describe allosteric behavior, taking into account energetics as well as conformational rearrangements and fluctuations. In the following Review, we discuss the use of solution NMR techniques designed to probe allosteric mechanisms in enzymes. NMR spectroscopy is unequaled in its ability to detect structural and dynamical changes in biomolecules, and the case studies presented herein demonstrate the range of insights to be gained from this valuable method. We also provide a detailed technical discussion of several specialized NMR experiments that are ideally suited for the study of enzymatic allostery.
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Affiliation(s)
- George P. Lisi
- Department of Chemistry, Yale University, New Haven, CT 06520
| | - J. Patrick Loria
- Department of Chemistry, Yale University, New Haven, CT 06520
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520
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Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E. Glycogen metabolism in humans. BBA CLINICAL 2016; 5:85-100. [PMID: 27051594 PMCID: PMC4802397 DOI: 10.1016/j.bbacli.2016.02.001] [Citation(s) in RCA: 264] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/10/2016] [Accepted: 02/16/2016] [Indexed: 12/31/2022]
Abstract
In the human body, glycogen is a branched polymer of glucose stored mainly in the liver and the skeletal muscle that supplies glucose to the blood stream during fasting periods and to the muscle cells during muscle contraction. Glycogen has been identified in other tissues such as brain, heart, kidney, adipose tissue, and erythrocytes, but glycogen function in these tissues is mostly unknown. Glycogen synthesis requires a series of reactions that include glucose entrance into the cell through transporters, phosphorylation of glucose to glucose 6-phosphate, isomerization to glucose 1-phosphate, and formation of uridine 5'-diphosphate-glucose, which is the direct glucose donor for glycogen synthesis. Glycogenin catalyzes the formation of a short glucose polymer that is extended by the action of glycogen synthase. Glycogen branching enzyme introduces branch points in the glycogen particle at even intervals. Laforin and malin are proteins involved in glycogen assembly but their specific function remains elusive in humans. Glycogen is accumulated in the liver primarily during the postprandial period and in the skeletal muscle predominantly after exercise. In the cytosol, glycogen breakdown or glycogenolysis is carried out by two enzymes, glycogen phosphorylase which releases glucose 1-phosphate from the linear chains of glycogen, and glycogen debranching enzyme which untangles the branch points. In the lysosomes, glycogen degradation is catalyzed by α-glucosidase. The glucose 6-phosphatase system catalyzes the dephosphorylation of glucose 6-phosphate to glucose, a necessary step for free glucose to leave the cell. Mutations in the genes encoding the enzymes involved in glycogen metabolism cause glycogen storage diseases.
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Affiliation(s)
- María M. Adeva-Andany
- Nephrology Division, Hospital General Juan Cardona, c/ Pardo Bazán s/n, 15406 Ferrol, Spain
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Sakamoto E, Seino Y, Fukami A, Mizutani N, Tsunekawa S, Ishikawa K, Ogata H, Uenishi E, Kamiya H, Hamada Y, Sato H, Harada N, Toyoda Y, Miwa I, Nakamura J, Inagaki N, Oiso Y, Ozaki N. Ingestion of a moderate high-sucrose diet results in glucose intolerance with reduced liver glucokinase activity and impaired glucagon-like peptide-1 secretion. J Diabetes Investig 2014; 3:432-40. [PMID: 24843603 PMCID: PMC4019243 DOI: 10.1111/j.2040-1124.2012.00208.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Aims/Introduction: Excessive intake of sucrose can cause severe health issues, such as diabetes mellitus. In animal studies, consumption of a high‐sucrose diet (SUC) has been shown to cause obesity, insulin resistance and glucose intolerance. However, several in vivo experiments have been carried out using diets with much higher sucrose contents (50–70% of the total calories) than are typically ingested by humans. In the present study, we examined the effects of a moderate SUC on glucose metabolism and the underlying mechanism. Materials and Methods: C57BL/6J mice received a SUC (38.5% sucrose), a high‐starch diet (ST) or a control diet for 5 weeks. We assessed glucose tolerance, incretin secretion and liver glucose metabolism. Results: An oral glucose tolerance test (OGTT) showed that plasma glucose levels in the early phase were significantly higher in SUC‐fed mice than in ST‐fed or control mice, with no change in plasma insulin levels at any stage. SUC‐fed mice showed a significant improvement in insulin sensitivity. Glucagon‐like peptide‐1 (GLP‐1) secretion 15 min after oral glucose administration was significantly lower in SUC‐fed mice than in ST‐fed or control mice. Hepatic glucokinase (GCK) activity was significantly reduced in SUC‐fed mice. During the OGTT, the accumulation of glycogen in the liver was suppressed in SUC‐fed mice in a time‐dependent manner. Conclusions: These results indicate that mice that consume a moderate SUC show glucose intolerance with a reduction in hepatic GCK activity and impairment in GLP‐1 secretion. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00208.x, 2012)
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Affiliation(s)
- Eriko Sakamoto
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Yusuke Seino
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine ; Department of Metabolic Medicine, Nagoya University School of Medicine
| | - Ayako Fukami
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Naohiro Mizutani
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Shin Tsunekawa
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Kota Ishikawa
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Hidetada Ogata
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Eita Uenishi
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | | | - Yoji Hamada
- Department of Metabolic Medicine, Nagoya University School of Medicine
| | - Hiroyuki Sato
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University
| | - Norio Harada
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yukiyasu Toyoda
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University
| | - Ichitomo Miwa
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University
| | | | - Nobuya Inagaki
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yutaka Oiso
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine
| | - Nobuaki Ozaki
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine ; Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya
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Saibi W, Gargouri A. Hydroxyl distribution in sugar structure and its contributory role in the inhibition of Stachybotrys microspora β-glucosidase (bglG). Carbohydr Res 2011; 346:1848-54. [DOI: 10.1016/j.carres.2011.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/08/2011] [Accepted: 06/14/2011] [Indexed: 11/29/2022]
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Wang Q, Nomura CT. Monitoring differences in gene expression levels and polyhydroxyalkanoate (PHA) production in Pseudomonas putida KT2440 grown on different carbon sources. J Biosci Bioeng 2010; 110:653-9. [DOI: 10.1016/j.jbiosc.2010.08.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 07/27/2010] [Accepted: 08/02/2010] [Indexed: 11/27/2022]
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Bazalová Z, Rypácková B, Broz J, Brunerová L, Polák J, Rusavý Z, Treslová L, Andel M. Three novel mutations in MODY and its phenotype in three different Czech families. Diabetes Res Clin Pract 2010; 88:132-8. [PMID: 20132997 DOI: 10.1016/j.diabres.2010.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 12/19/2009] [Accepted: 01/04/2010] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS MODY (Maturity Onset Diabetes of the Young) is an autosomal dominant inherited type of diabetes with significant genetic heterogeneity. New mutations causing MODY are still being found. A genetically confirmed diagnosis of MODY allows application of individualized treatment based on the underlying concrete genetic dysfunction. Detection of novel MODY mutations helps provide a more complete picture of the possible MODY genotypes. MATERIALS AND METHODS We tested 43 adult Czech patients with clinical characteristics of MODY, using direct sequencing of HNF1A (hepatocyte nuclear factor 1-alpha), HNF4A (hepatocyte nuclear factor 4-alpha) and GCK (glucokinase) genes. RESULTS In three Czech families we identified three novel mutations we believe causing MODY-two missense mutations in HNF1A [F268L (c.802T>C) and P291S (c.871C>T)] and one frame shift mutation in GCK V244fsdelG (c.729delG). Some of the novel HNF1A mutation carriers were successfully transferred from insulin to gliclazide, while some of the novel GCK mutation carriers had a good clinical response when switched from insulin or oral antidiabetic drugs to diet. CONCLUSION We describe three novel MODY mutations in three Czech families. The identification of MODY mutations had a meaningful impact on therapy on the mutation carriers.
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Affiliation(s)
- Z Bazalová
- 3rd Faculty of Medicine of Charles University, Centre of Research for Diabetes, Endocrinological Diseases and Clinical Nutrition, Ruská 87, 100 00 Prague 10, Czech Republic.
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Kroth PG, Chiovitti A, Gruber A, Martin-Jezequel V, Mock T, Parker MS, Stanley MS, Kaplan A, Caron L, Weber T, Maheswari U, Armbrust EV, Bowler C. A model for carbohydrate metabolism in the diatom Phaeodactylum tricornutum deduced from comparative whole genome analysis. PLoS One 2008; 3:e1426. [PMID: 18183306 PMCID: PMC2173943 DOI: 10.1371/journal.pone.0001426] [Citation(s) in RCA: 281] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 12/11/2007] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Diatoms are unicellular algae responsible for approximately 20% of global carbon fixation. Their evolution by secondary endocytobiosis resulted in a complex cellular structure and metabolism compared to algae with primary plastids. METHODOLOGY/PRINCIPAL FINDINGS The whole genome sequence of the diatom Phaeodactylum tricornutum has recently been completed. We identified and annotated genes for enzymes involved in carbohydrate pathways based on extensive EST support and comparison to the whole genome sequence of a second diatom, Thalassiosira pseudonana. Protein localization to mitochondria was predicted based on identified similarities to mitochondrial localization motifs in other eukaryotes, whereas protein localization to plastids was based on the presence of signal peptide motifs in combination with plastid localization motifs previously shown to be required in diatoms. We identified genes potentially involved in a C4-like photosynthesis in P. tricornutum and, on the basis of sequence-based putative localization of relevant proteins, discuss possible differences in carbon concentrating mechanisms and CO(2) fixation between the two diatoms. We also identified genes encoding enzymes involved in photorespiration with one interesting exception: glycerate kinase was not found in either P. tricornutum or T. pseudonana. Various Calvin cycle enzymes were found in up to five different isoforms, distributed between plastids, mitochondria and the cytosol. Diatoms store energy either as lipids or as chrysolaminaran (a beta-1,3-glucan) outside of the plastids. We identified various beta-glucanases and large membrane-bound glucan synthases. Interestingly most of the glucanases appear to contain C-terminal anchor domains that may attach the enzymes to membranes. CONCLUSIONS/SIGNIFICANCE Here we present a detailed synthesis of carbohydrate metabolism in diatoms based on the genome sequences of Thalassiosira pseudonana and Phaeodactylum tricornutum. This model provides novel insights into acquisition of dissolved inorganic carbon and primary metabolic pathways of carbon in two different diatoms, which is of significance for an improved understanding of global carbon cycles.
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Affiliation(s)
- Peter G Kroth
- Fachbereich Biologie, University of Konstanz, Konstanz, Germany.
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Zhang J, Li C, Chen K, Zhu W, Shen X, Jiang H. Conformational transition pathway in the allosteric process of human glucokinase. Proc Natl Acad Sci U S A 2006; 103:13368-73. [PMID: 16938872 PMCID: PMC1569170 DOI: 10.1073/pnas.0605738103] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Indexed: 12/25/2022] Open
Abstract
Glucokinase (GK) is an important enzyme for regulating blood glucose levels and a potentially attractive target for diabetes of the young type 2 and persistent hyperinsulinemic hypoglycemia of infancy. To characterize the conformational transition of GK from the closed state to the superopen state, a series of conventional molecular dynamics (MD) and target MD (TMD) simulations were performed on both the wild-type enzyme and its mutants. Two 10-ns conventional MD simulations showed that, although the allosteric site of GK is approximately 20 A away from the active site, the activator is able to enhance the activity of the enzyme through conformational restriction. Fourteen TMD simulations on GK and five of its mutants revealed a reliably conformational transition pathway. The overall conformational transition includes three stages, and three likely stable intermediate states were identified by free energy scanning for the snapshots throughout the pathway. The conformational transition feature revealed by our TMD simulations rationalized several important mutagenesis and kinetic data. Remarkably, the TMD simulations predicted that Y61S, I159A, A201R, V203E, and V452S mutations, which have not been investigated so far, may facilitate the opening process of GK. These predictions also have been verified by mutagenesis and kinetic analyses in this study. These observations are beneficial to understanding the mechanism of GK regulation and designing the compounds for treating metabolic diseases.
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Affiliation(s)
- Jian Zhang
- Center for Drug Discovery and Design, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; and
| | - Chenjing Li
- Center for Drug Discovery and Design, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; and
| | - Kaixian Chen
- Center for Drug Discovery and Design, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; and
| | - Weiliang Zhu
- Center for Drug Discovery and Design, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; and
| | - Xu Shen
- Center for Drug Discovery and Design, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; and
| | - Hualiang Jiang
- Center for Drug Discovery and Design, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, and Graduate School, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; and
- School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
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Marotta DE, Anand GR, Anderson TA, Miller SP, Okar DA, Levitt DG, Lange AJ. Identification and characterization of the ATP-binding site in human pancreatic glucokinase. Arch Biochem Biophys 2005; 436:23-31. [PMID: 15752705 DOI: 10.1016/j.abb.2005.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 01/19/2005] [Indexed: 11/25/2022]
Abstract
The central role of human pancreatic glucokinase in insulin secretion and, consequently, in maintenance of blood glucose levels has prompted investigation into identification of ATP-binding site residues and examination of ATP- and glucose-binding interactions. Because glucokinase has been resistant to crystallization, computer generated homology models were developed based on the X-ray crystal structure of the COOH-terminal domain of human brain hexokinase 1 bound to glucose and ADP or glucose and glucose-6-phosphate. Human pancreatic glucokinase mutants were designed based upon these models and on ATPase domain sequence conservation to identify and characterize potential glucose and ATP-binding sites. Specifically, mutants Asp78Ala, Thr82Ala, Lys90Ala, Lys102Ala, Gly227Ala, Thr228Ala, Ser336Leu, Ser411Ala, and Ser411Leu were constructed, expressed, purified, and kinetically characterized under steady-state conditions. Compared to their respective wild type controls, several mutants demonstrated dramatic changes in V(max), cooperativity of glucose binding and S(0.5) for ATP and glucose. Results suggest a role for Asp78, Thr82, Gly227, Thr228, and Ser336 in ATP binding and indicate these residues are essential for glucose phosphorylation by human pancreatic glucokinase.
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Affiliation(s)
- Diane E Marotta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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Basu R, Basu A, Johnson CM, Schwenk WF, Rizza RA. Insulin dose-response curves for stimulation of splanchnic glucose uptake and suppression of endogenous glucose production differ in nondiabetic humans and are abnormal in people with type 2 diabetes. Diabetes 2004; 53:2042-50. [PMID: 15277384 DOI: 10.2337/diabetes.53.8.2042] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To determine whether the insulin dose-response curves for suppression of endogenous glucose production (EGP) and stimulation of splanchnic glucose uptake (SGU) differ in nondiabetic humans and are abnormal in type 2 diabetes, 14 nondiabetic and 12 diabetic subjects were studied. Glucose was clamped at approximately 9.5 mmol/l and endogenous hormone secretion inhibited by somatostatin, while glucagon and growth hormone were replaced by an exogenous infusion. Insulin was progressively increased from approximately 150 to approximately 350 and approximately 700 pmol/l by means of an exogenous insulin infusion, while EGP, SGU, and leg glucose uptake (LGU) were measured using the splanchnic and leg catheterization methods, combined with a [3-3H]glucose infusion. In nondiabetic subjects, an increase in insulin from approximately 150 to approximately 350 pmol/l resulted in maximal suppression of EGP, whereas SGU continued to increase (P < 0.001) when insulin was increased to approximately 700 pmol/l. In contrast, EGP progressively decreased (P < 0.001) and SGU progressively increased (P < 0.001) in the diabetic subjects as insulin increased from approximately 150 to approximately 700 pmol/l. Although EGP was higher (P < 0.01) in the diabetic than nondiabetic subjects only at the lowest insulin concentration, SGU was lower (P < 0.01) in the diabetic subjects at all insulin concentrations tested. On the other hand, in contrast to LGU and overall glucose disposal, the increment in SGU in response to both increments in insulin did not differ in the diabetic and nondiabetic subjects, implying a right shifted but parallel dose-response curve. These data indicate that the dose-response curves for suppression of glucose production and stimulation of glucose uptake differ in nondiabetic subjects and are abnormal in people with type 2 diabetes. Taken together, these data also suggest that agents that enhance SGU in diabetic patients (e.g. glucokinase activators) are likely to improve glucose tolerance.
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Affiliation(s)
- Rita Basu
- Division of Endocrinology, Mayo Clinic, Rochester, Minnesota 55905, USA
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15
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Adkins A, Basu R, Persson M, Dicke B, Shah P, Vella A, Schwenk WF, Rizza R. Higher insulin concentrations are required to suppress gluconeogenesis than glycogenolysis in nondiabetic humans. Diabetes 2003; 52:2213-20. [PMID: 12941759 DOI: 10.2337/diabetes.52.9.2213] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To determine the mechanism(s) by which insulin inhibits endogenous glucose production (EGP) in nondiabetic humans, insulin was infused at rates of 0.25, 0.375, or 0.5 mU. kg(-1). min(-1) and glucose was clamped at approximately 5.5 mmol/l. EGP, gluconeogenesis, and uridine-diphosphoglucose (UDP)-glucose flux were measured using [3-(3)H]glucose, deuterated water, and the acetaminophen glucuronide methods, respectively. An increase in insulin from approximately 75 to approximately 100 to approximately 150 pmol/l ( approximately 12.5 to approximately 17 to approximately 25 microU/ml) resulted in progressive (ANOVA; P < 0.02) suppression of EGP (13.1 +/- 1.3 vs. 11.7 +/- 1.03 vs. 6.4 +/- 2.15 micromol x kg(-1) x min(-1)) that was entirely due to a progressive decrease (ANOVA; P < 0.05) in the contribution of glycogenolysis to EGP (4.7 +/- 1.7 vs. 3.4 +/- 1.2 vs. -2.1 +/- 1.3 micro mol x kg(-1) x min(-1)). In contrast, both the contribution of gluconeogenesis to EGP (8.4 +/- 1.0 vs. 8.3 +/- 1.1 vs. 8.5 +/- 1.3 micro mol x kg(-1) x min(-1)) and UDP-glucose flux (5.0 +/- 0.4 vs. 5.0 +/- 0.3 vs. 4.0 +/- 0.5 micro mol x kg(-1) x min(-1)) remained unchanged. The contribution of the direct (extracellular) pathway to UDP-glucose flux was minimal and constant during all insulin infusions. We conclude that higher insulin concentrations are required to suppress the contribution of gluconeogenesis of EGP than are required to suppress the contribution of glycogenolysis to EGP in healthy nondiabetic humans. Since suppression of glycogenolysis occurred without a decrease in UDP-glucose flux, this implies that insulin inhibits EGP, at least in part, by directing glucose-6-phosphate into glycogen rather than through the glucose-6-phosphatase pathway.
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Affiliation(s)
- Aron Adkins
- Endocrine Research Unit, Mayo Foundation, Rochester, Minnesota 55905, USA
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16
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Pedersen PL, Mathupala S, Rempel A, Geschwind JF, Ko YH. Mitochondrial bound type II hexokinase: a key player in the growth and survival of many cancers and an ideal prospect for therapeutic intervention. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:14-20. [PMID: 12206885 DOI: 10.1016/s0005-2728(02)00248-7] [Citation(s) in RCA: 265] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Despite more than 75 years of research by some of the greatest scientists in the world to conquer cancer, the clear winner is still cancer. This is reflected particularly by liver cancer that worldwide ranks fourth in terms of mortality with survival rates of no more than 3-5%. Significantly, one of the earliest discovered hallmarks of cancer had its roots in Bioenergetics as many tumors were found in the 1920s to exhibit a high glycolytic phenotype. Although research directed at unraveling the underlying basis and significance of this phenotype comprised the focus of cancer research for almost 50 years, these efforts declined greatly from 1970 to 1990 as research into the molecular and cell biology of this disease gained center stage. Certainly, this change was necessary as the new knowledge obtained about oncogenes, gene regulation, and programmed cell death once again placed Bioenergetics in the limelight of cancer research. Thus, we now have a much better molecular understanding of the high glycolytic phenotype of many cancers, the pivotal roles that Type II hexokinase-mitochondrial interactions play in this process to promote tumor cell growth and survival, and how this new knowledge can lead to improved therapies that may ultimately turn the tide on our losing war on cancer.
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Affiliation(s)
- Peter L Pedersen
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205-2185, USA.
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17
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Shah P, Vella A, Basu A, Basu R, Adkins A, Schwenk WF, Johnson CM, Nair KS, Jensen MD, Rizza RA. Effects of free fatty acids and glycerol on splanchnic glucose metabolism and insulin extraction in nondiabetic humans. Diabetes 2002; 51:301-10. [PMID: 11812736 DOI: 10.2337/diabetes.51.2.301] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The present study sought to determine whether elevated plasma free fatty acids (FFAs) alter the ability of insulin and glucose to regulate splanchnic as well as muscle glucose metabolism. To do so, FFAs were increased in 10 subjects to approximately 1 mmol/l by an 8-h Intralipid/heparin (IL/Hep) infusion, whereas they fell to levels near the detection limit of the assay (<0.05 mmol/l) in 13 other subjects who were infused with glycerol alone at rates sufficient to either match (n = 5, low glycerol) or double (n = 8, high glycerol) the plasma glycerol concentrations observed during the IL/Hep infusion. Glucose was clamped at approximately 8.3 mmol/l, and insulin was increased to approximately 300 pmol/l to stimulate both muscle and hepatic glucose uptake. Insulin secretion was inhibited with somatostatin. Leg and splanchnic glucose metabolism were assessed using a combined catheter and tracer dilution approach. Leg glucose uptake (21.7 +/- 3.5 vs. 48.3 +/- 9.3 and 57.8 +/- 11.7 micromol x kg(-1) leg x min(-1)) was lower (P < 0.001) during IL/Hep than the low- or high-glycerol infusions, confirming that elevated FFAs caused insulin resistance in muscle. IL/Hep did not alter splanchnic glucose uptake or the contribution of the extracellular direct pathway to UDP-glucose flux. On the other hand, total UDP-glucose flux (13.2 +/- 1.7 and 12.5 +/- 1.0 vs. 8.1 +/- 0.5 micromol x kg(-1) x min(-1)) and flux via the indirect intracellular pathway (8.4 +/- 1.2 and 8.1 +/- 0.6 vs. 4.8 +/- 0.05 micromol x kg(-1) x min(-1)) were greater (P < 0.05) during both the IL/Hep and high-glycerol infusions than the low-glycerol infusion. In contrast, only IL/Hep increased (P < 0.05) splanchnic glucose production, indicating that elevated FFAs impaired the ability of the liver to autoregulate. Splanchnic insulin extraction, directly measured using the arterial and hepatic vein catheters, did not differ (67 +/- 3 vs. 71 +/- 5 vs. 69 +/- 1%) during IL/Hep and high- and low-glycerol infusions. We conclude that elevated FFAs exert multiple effects on glucose metabolism. They inhibit insulin- and glucose-induced stimulation of muscle glucose uptake and suppression of splanchnic glucose production. They increase the contribution of the indirect pathway to glycogen synthesis and impair hepatic autoregulation. On the other hand, they do not alter either splanchnic glucose uptake or splanchnic insulin extraction in nondiabetic humans.
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Affiliation(s)
- Pankaj Shah
- Endocrine Research Unit, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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18
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19
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Ko YH, Pedersen PL, Geschwind JF. Glucose catabolism in the rabbit VX2 tumor model for liver cancer: characterization and targeting hexokinase. Cancer Lett 2001; 173:83-91. [PMID: 11578813 DOI: 10.1016/s0304-3835(01)00667-x] [Citation(s) in RCA: 263] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The rabbit VX2 tumor when implanted in the liver has proven convenient as a model for studying hepatocellular carcinomas. However, its metabolic properties have not been well studied. Significantly, studies described here show that the VX2 tumor exhibits a high glycolytic/high hexokinase phenotype that is retained following implantation and growth in rabbit liver. In addition, results of a limited screen show that the glycolytic rate is inhibited best by 2-deoxyglucose (2DOG) and 3-bromopyruvate (3BrPA), the former compound of which is phosphorylated by hexokinase but not further metabolized, while the latter directly inhibits hexokinase. Finally, when tested on hepatoma cells in culture both inhibitors facilitated cell death. These studies underscore the usefulness of the VX2 tumor model for the study of advanced liver cancer and for selecting anti-hepatoma agents.
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Affiliation(s)
- Y H Ko
- Department of Biological Chemistry, Johns Hopkins University, School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA
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20
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Basu A, Basu R, Shah P, Vella A, Johnson CM, Jensen M, Nair KS, Schwenk WF, Rizza RA. Type 2 diabetes impairs splanchnic uptake of glucose but does not alter intestinal glucose absorption during enteral glucose feeding: additional evidence for a defect in hepatic glucokinase activity. Diabetes 2001; 50:1351-62. [PMID: 11375336 DOI: 10.2337/diabetes.50.6.1351] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have previously reported that splanchnic glucose uptake, hepatic glycogen synthesis, and hepatic glucokinase activity are decreased in people with type 2 diabetes during intravenous glucose infusion. To determine whether these defects are also present during more physiological enteral glucose administration, we studied 11 diabetic and 14 nondiabetic volunteers using a combined organ catheterization-tracer infusion technique. Glucose was infused into the duodenum at a rate of 22 micromol. kg(-1). min(-1) while supplemental glucose was given intravenously to clamp glucose at approximately 10 mmol/l in both groups. Endogenous hormone secretion was inhibited with somatostatin, and insulin was infused to maintain plasma concentrations at approximately 300 pmol/l (i.e., twofold higher than our previous experiments). Total body glucose disappearance, splanchnic, and leg glucose extractions were markedly lower (P < 0.01) in the diabetic subjects than in the nondiabetic subjects. UDP-glucose flux, a measure of glycogen synthesis, was approximately 35% lower (P < 0.02) in the diabetic subjects than in the nondiabetic subjects. This was entirely accounted for by a decrease (P < 0.01) in the contribution of extracellular glucose because the contribution of the indirect pathway to hepatic glycogen synthesis was similar between groups. Neither endogenous and splanchnic glucose productions nor rates of appearance of the intraduodenally infused glucose in the portal vein differed between groups. In summary, both muscle and splanchnic glucose uptake are impaired in type 2 diabetes during enteral glucose administration. The defect in splanchnic glucose uptake appears to be due to decreased uptake of extracellular glucose, implying decreased glucokinase activity. Thus, abnormal hepatic and muscle (but not gut) glucose metabolism are likely to contribute to postprandial hyperglycemia in people with type 2 diabetes.
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Affiliation(s)
- A Basu
- Division of Endocrinology, Metabolism and Nutrition, Mayo Clinic and Foundation, 200 1st St, SW, Rochester, MN 55905, USA
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21
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Daikoku T, Shinohara Y, Shima A, Yamazaki N, Terada H. Specific elevation of transcript levels of particular protein subtypes induced in brown adipose tissue by cold exposure. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1457:263-72. [PMID: 10773170 DOI: 10.1016/s0005-2728(00)00107-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To understand the difference in metabolic flow in rat brown adipose tissue (BAT) from that in white adipose tissue (WAT) at the molecular level, we examined the steady-state transcript levels of 39 proteins in both adipose tissues with and without cold exposure by Northern blot analysis. In addition to the transcript levels of uncoupling protein isoforms, those of proteins involved in the transport and catabolism of fatty acids and glucose in BAT were elevated by cold exposure, suggesting the stimulation of utilization of fatty acids and glucose as fuels in BAT. As to these changes, the muscle-type subtypes were remarkable; and therefore, they were suggested to be responsible for the cold exposure-induced acceleration of energy expenditure in BAT. Furthermore, of the isoforms of beta-adrenergic receptor (beta-AR) and CCAAT enhancer binding protein (C/EBP), transcript levels of beta(1)-AR and C/EBPbeta in BAT were increased by the cold exposure. Possible roles of these proteins in energy metabolism in BAT were discussed.
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Affiliation(s)
- T Daikoku
- Faculty of Pharmaceutical Sciences, University of Tokushima, Shomachi-1, Tokushima, Japan
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22
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Tiedge M, Richter T, Lenzen S. Importance of cysteine residues for the stability and catalytic activity of human pancreatic beta cell glucokinase. Arch Biochem Biophys 2000; 375:251-60. [PMID: 10700381 DOI: 10.1006/abbi.1999.1666] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The low-affinity glucose phosphorylating enzyme glucokinase has the function of a physiological glucose sensor in pancreatic beta cells and in liver. In contrast to the high-affinity hexokinase types I-III glucokinase shows extraordinary sensitivity toward SH group oxidizing compounds. To characterize the function of sulfhydryl groups cysteine residues in the vicinity of the sugar binding site (Cys 213, Cys 220, Cys 230, Cys 233, and Cys 252) as well as cysteine residues a distance from the active site (Cys 364, Cys 371, and Cys 382), they were replaced in human beta cell glucokinase by serine through site-directed mutagenesis. Controlled proteolysis of wild-type glucokinase by proteinase K revealed that the SH group oxidizing agent alloxan can induce the formation of multiple intramolecular disulfide bridges corresponding to a double-band pattern of glucokinase protein in nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The formation of intramolecular disulfide bridges altered the mobility of the protein. None of the cysteine mutations could prevent the formation of the 49-kDa glucokinase conformation after alloxan treatment. The cysteine mutants Cys 233, Cys 252, and Cys 382 showed nearly complete loss of catalytic activity, whereas the V(max) values of the Cys 213, Cys 220, Cys 364, and Cys 371 mutants were decreased by 30-60%. Only the Cys 230 mutant showed kinetic characteristics comparable to those of wild-type glucokinase. The sensitivity of the Cys 213, Cys 230, Cys 364, and Cys 371 mutants toward alloxan-induced inhibition of enzyme activity was up to 10-fold lower compared with wild-type glucokinase. d-Glucose and dithiotreitol provided protection against alloxan-induced inhibition of wild-type glucokinase and all catalytically active cysteine mutants. Conclusively our data demonstrate the functional significance of the cysteine residues of beta cell glucokinase for both structural instability of the enzyme and catalytic function. Knowledge of sensitive cysteine targets may help to develop strategies that improve glucokinase enzyme function under conditions of oxidative stress.
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Affiliation(s)
- M Tiedge
- Institute of Clinical Biochemistry, Hannover, D-30623, Germany
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23
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Abstract
Red blood cell enzyme activities are measured mainly to diagnose hereditary nonspherocytic hemolytic anemia associated with enzyme anomalies. At least 15 enzyme anomalies associated with hereditary hemolytic anemia have been reported. Some nonhematologic disease can also be diagnosed by the measurement of red blood cell enzyme activities in the case in which enzymes of red blood cells and the other organs are under the same genetic control. Progress in molecular biology has provided a new perspective. Techniques such as the polymerase chain reaction and single-strand conformation polymorphism analysis have greatly facilitated the molecular analysis of erythroenzymopathies. These studies have clarified the correlation between the functional and structural abnormalities of the variant enzymes. In general, the mutations that induce an alteration of substrate binding site and/or enzyme instability might result in markedly altered enzyme properties and severe clinical symptoms.
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Affiliation(s)
- H Fujii
- Department of Blood Transfusion Medicine, Tokyo Women's Medical College, Japan
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24
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Pego JV, Weisbeek PJ, Smeekens SC. Mannose inhibits Arabidopsis germination via a hexokinase-mediated step. PLANT PHYSIOLOGY 1999; 119:1017-23. [PMID: 10069839 PMCID: PMC32082 DOI: 10.1104/pp.119.3.1017] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/1998] [Accepted: 12/03/1998] [Indexed: 05/18/2023]
Abstract
Low concentrations of the glucose (Glc) analog mannose (Man) inhibit germination of Arabidopsis seeds. Man is phosphorylated by hexokinase (HXK), but the absence of germination was not due to ATP or phosphate depletion. The addition of metabolizable sugars reversed the Man-mediated inhibition of germination. Carbohydrate-mediated regulation of gene expression involving a HXK-mediated pathway is known to be activated by Glc, Man, and other monosaccharides. Therefore, we investigated whether Man blocks germination through this system. By testing other Glc analogs, we found that 2-deoxyglucose, which, like Man, is phosphorylated by HXK, also blocked germination; no inhibition was observed with 6-deoxyglucose or 3-O-methylglucose, which are not substrates for HXK. Since these latter two sugars are taken up at a rate similar to that of Man, uptake is unlikely to be involved in the inhibition of germination. Furthermore, we show that mannoheptulose, a specific HXK inhibitor, restores germination of seeds grown in the presence of Man. We conclude that HXK is involved in the Man-mediated repression of germination of Arabidopsis seeds, possibly via energy depletion.
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Affiliation(s)
- J V Pego
- Department of Botanical Ecology and Evolutionary Biology, University of Utrecht. Padualaan 8, 3584 CH Utrecht, The Netherlands.
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25
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Dufresne CP, Wood TD, Hendrickson CL. High-resolution electrospray ionization Fourier transform mass spectrometry with infrared multiphoton dissociation of glucokinase from Bacillus Stearothermophilus. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1998; 9:1222-1225. [PMID: 9794087 DOI: 10.1016/s1044-0305(98)00102-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Glucokinase (GK, EC 2.7.1.2), a member of the enzyme family of hexokinases, has been shown to be linked to maturity-onset diabetes of the young type II (MODY-2). Although nucleotide and amino acid sequence information are available for the human varieties, they are not known for the variety from Bacillus stearothermophilus, which is often used in protein binding studies. Here, a combination of electrospray Fourier transform mass spectrometry (FTMS) and infrared multiphoton dissociation (IRMPD) is used to obtain accurate molecular weight and preliminary amino acid sequence information for the protein. Electrospray FTMS provides evidence of a solution phase dimer. In addition, dithiothreitol reduction shows no shift in high-resolution isotopic distributions, indicating a probable absence of disulfide bonds in the protein. The partial sequence information obtained from IRMPD could be the basis for creating a DNA probe for the protein.
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Affiliation(s)
- C P Dufresne
- Department of Chemistry, State University of New York at Buffalo 14260-3000, USA
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26
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Affiliation(s)
- Y J Hei
- Pharmaceutical Research Institute, Bristol-Myers Squibb, Buffalo, NY 14213, USA
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27
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Foster JD, Young SE, Brandt TD, Nordlie RC. Tungstate: a potent inhibitor of multifunctional glucose-6-phosphatase. Arch Biochem Biophys 1998; 354:125-32. [PMID: 9633606 DOI: 10.1006/abbi.1998.0695] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The insulin-like action of tungstate in diabetic rats (A. Barberà et al., 1994, J. Biol. Chem. 269, 20047-20053) prompted us to examine the effects of tungstate on the glucose-6-phosphatase system. Our results indicate that tungstate is a potent inhibitor of glucose-6-phosphatase, with a Ki in the 10-25 microM range determined with native microsomes and in the 1-7 microM range determined with detergent-treated microsomes. With both preparations, simple linear competitive inhibition was observed versus glucose 6-phosphate (glucose-6-P) as substrate with the glucose-6-P phosphohydrolase activity of the enzyme. Tungstate was a simple linear competitive inhibitor versus carbamyl phosphate (carbamyl-P) and a linear noncompetitive inhibitor versus glucose with the carbamyl-P:glucose phosphotransferase activity of the glucose-6-phosphatase system. These findings, in addition to the observation that tungstate protected the enzyme against thermal inactivation, indicate that tungstate binds with high affinity and competes at the active site of the enzyme where the substrates glucose-6-P and carbamyl-P bind prior to catalysis. Our results suggest that potent inhibition of glucose-6-P hydrolysis by tungstate is likely responsible, at least in part, for the normalization of glycemia and the rebound in hepatic glucose-6-P levels observed in earlier studies in which tungstate exhibited insulin-like action in diabetic rats.
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Affiliation(s)
- J D Foster
- Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine and Health Sciences, Grand Forks 58203, USA
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28
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Wood TD, Guan Z, Borders CL, Chen LH, Kenyon GL, McLafferty FW. Creatine kinase: essential arginine residues at the nucleotide binding site identified by chemical modification and high-resolution tandem mass spectrometry. Proc Natl Acad Sci U S A 1998; 95:3362-5. [PMID: 9520370 PMCID: PMC19840 DOI: 10.1073/pnas.95.7.3362] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Phenylglyoxal is an arginine-specific reagent that inactivates creatine kinase (CK). Previous results suggest that modification of the dimeric enzyme at a single arginine residue per subunit causes complete inactivation accompanied by the loss of nucleotide binding; the actual site of modification was not identified. Here, high-resolution tandem mass spectrometry (MS/MS) was used to identify three phenylglyoxal-modified Arg residues in monomeric rabbit muscle CK. Electrospray ionizaton Fourier-transform MS of the phenylglyoxal-modified CK that had lost approximately 80% activity identified three species: unmodified, once-modified (+116 Da), and twice-modified (+232 Da) enzyme in a ratio of approximately 1:4:1. MS/MS restricts the derivatized sites to P122-P212 and P283-V332, whereas MS of Lys-C digestions revealed two modified peptides, A266-K297 and G116-K137. The only Arg in A266-K297 is Arg-291 (invariant), whereas MS/MS of modified G116-K137 shows that two of the three sites Arg-129, Arg-131, or Arg-134 (all invariant) can contain the modification. The recently reported x-ray crystal structure for the octameric chicken mitochondrial CK indicates that its nucleotide triphosphate-binding site indeed contains the equivalent of R291, R129, and R131 reported here to be at the active site of rabbit muscle CK.
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Affiliation(s)
- T D Wood
- Department of Chemistry, Natural Sciences Complex, State University of New York, Buffalo, NY 14260-3000, USA
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29
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Glaser B, Kesavan P, Heyman M, Davis E, Cuesta A, Buchs A, Stanley CA, Thornton PS, Permutt MA, Matschinsky FM, Herold KC. Familial hyperinsulinism caused by an activating glucokinase mutation. N Engl J Med 1998; 338:226-30. [PMID: 9435328 DOI: 10.1056/nejm199801223380404] [Citation(s) in RCA: 430] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- B Glaser
- Department of Endocrinology and Metabolism, Hebrew University Hadassah Medical School, Jerusalem, Israel
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30
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Shinohara Y, Yamamoto K, Inoo K, Yamazaki N, Terada H. Quantitative determinations of the steady state transcript levels of hexokinase isozymes and glucose transporter isoforms in normal rat tissues and the malignant tumor cell line AH130. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1368:129-36. [PMID: 9459591 DOI: 10.1016/s0005-2736(97)00189-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The steady state transcript levels of the four hexokinase (HK) isozymes and four glucose transporter (GLUT) isoforms were determined quantitatively by Northern analysis of RNA samples from rat tissues using synthetic fragments of the RNAs encoding the HK isozymes and GLUT isoforms. Results showed that the levels of HK isozyme transcripts were low in rat tissues, the level of that most highly expressed, the type I isozyme (HKI), in the brain being 0.025% of the total poly(A)+ RNA. A good correlation was found between the reported HK activities and the total amounts of transcripts encoding all HK isozymes in various tissues, showing that the HK activities in tissues can be estimated from the total amount of transcripts encoding HK isozymes. The proposed associated expressions of HK isozymes and GLUT isoforms in particular tissues were confirmed at their transcript levels. The steady state transcript levels of type II HK and the type 1 GLUT isoform in the malignant tumor cell line AH130 were also determined quantitatively.
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Affiliation(s)
- Y Shinohara
- Faculty of Pharmaceutical Sciences, University of Tokushima, Japan.
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31
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Guazzini B, Gaffi D, Mainieri D, Multari G, Cordera R, Bertolini S, Pozza G, Meschi F, Barbetti F. Three novel missense mutations in the glucokinase gene (G80S; E221K; G227C) in Italian subjects with maturity-onset diabetes of the young (MODY). Hum Mutat 1998. [DOI: 10.1002/(sici)1098-1004(1998)12:2<136::aid-humu13>3.0.co;2-v] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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32
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Ma Z, Landt M, Bohrer A, Ramanadham S, Kipnis DM, Turk J. Interleukin-1 reduces the glycolytic utilization of glucose by pancreatic islets and reduces glucokinase mRNA content and protein synthesis by a nitric oxide-dependent mechanism. J Biol Chem 1997; 272:17827-35. [PMID: 9211938 DOI: 10.1074/jbc.272.28.17827] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Culture of rat pancreatic islets with interleukin-1 (IL-1) results in up-regulation of the inducible isoform of nitric oxide synthase and overproduction of nitric oxide (NO). This is associated with reversible inhibition of both glucose-induced insulin secretion and islet glucose oxidation, and these effects are prevented by the inducible nitric oxide synthase inhibitor NG-monomethylarginine. IL-1 also induces accumulation of nonesterified arachidonic acid in islets by an NO-dependent mechanism, and one potential explanation for that effect would involve an IL-1-induced enhancement of islet glycolytic flux. We have therefore examined effects of IL-1 on islet glycolytic utilization of glucose and find that culture of islets with IL-1 in medium containing 5.5 mM glucose results in suppression of islet glucose utilization subsequently measured at glucose concentrations between 6 and 18 mM. The IL-1-induced suppression of islet glucose utilization is associated with a decline in islet glucokinase mRNA content, as determined by competitive reverse transcriptase-polymerase chain reaction, and in glucokinase protein synthesis, as determined by immuoprecipitation experiments, and all of these effects are prevented by NG-monomethylarginine. These findings suggest that IL-1 can down-regulate islet glucokinase, which is the primary component of the islet glucose-sensor apparatus, by an NO-dependent mechanism. Because reductions in islet glucokinase levels are known to cause a form of type II diabetes mellitus, these observations raise the possibility that factors which increase islet NO levels might contribute to development of glucose intolerance.
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Affiliation(s)
- Z Ma
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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33
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Zeng C, Aleshin AE, Hardie JB, Harrison RW, Fromm HJ. ATP-binding site of human brain hexokinase as studied by molecular modeling and site-directed mutagenesis. Biochemistry 1996; 35:13157-64. [PMID: 8855953 DOI: 10.1021/bi960750e] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The interaction of ATP with the active site of hexokinase is unknown since the crystal structure of the hexokinase-ATP complex is unavailable. It was found that the ATP binding site of brain hexokinase is homologous to that of actin, heat shock protein hsc70, and glycerol kinase. On the basis of these similarities, the ATP molecule was positioned in the catalytic domain of human brain hexokinase, which was modeled from the X-ray structure of yeast hexokinase. Site-directed mutagenesis was performed to test the function of residues presumably involved in interaction with the tripolyphosphoryl moiety of ATP. Asp532, which is though to be involved in binding the Mg2+ ion of the MgATP2- complex, was mutated to Lys and Glu. The kcat values decreased 1000- and 200-fold, respectively, for the two mutants. Another residue, Thr680 was proposed to interact with the gamma-phosphoryl group of ATP through hydrogen bonds and was mutated to Val and Ser. The kcat value of the Thr680Val mutant decreased 2000-fold, whereas the kcat value of the Thr680Ser decreased only 2.5-fold, implying the importance of the hydroxyl group. The Km and dissociation constant values for either ATP or glucose of all the above mutants showed little or no change relative to the wild-type enzyme. The Ki values for the glucose 6-phosphate analogue 1,5-anhydroglucitol 6-phosphate, were the same as that of the wild-type enzyme, and the inhibition was reversed by inorganic phosphate (Pi) for all four mutants. The circular dichroism spectra of the mutants were the same as that of the wild-type enzyme. The results from the site-directed mutagenesis demonstrate that the presumed interactions of investigated residues with ATP are important for the stabilization of the transition state.
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Affiliation(s)
- C Zeng
- Department of Biochemistry and Biophysics, Iowa State University, Ames 50011, USA
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Veiga-da-Cunha M, Xu LZ, Lee YH, Marotta D, Pilkis SJ, Van Schaftingen E. Effect of mutations on the sensitivity of human beta-cell glucokinase to liver regulatory protein. Diabetologia 1996; 39:1173-9. [PMID: 8897004 DOI: 10.1007/bf02658503] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Human beta-cell glucokinase and its liver counterpart displayed a half-saturating concentration of glucose (S0.5) of about 8 mmol/l and a Hill coefficient of 1.7, and were as sensitive to inhibition by the rat liver regulatory protein as the rat liver enzyme. These results indicate that the N-terminal region of glucokinase, which differs among these three enzymes, is not implicated in the recognition of the regulatory protein. They also suggest that the regulatory protein, or a related protein, could modulate the affinity of glucokinase for glucose in beta cells. We have also tested the effect of several mutations, many of which are implicated in maturity onset diabetes of the young. The mutations affected the affinity for glucose and for the regulatory protein to different degrees, indicating that the binding site for these molecules is different. An Asp158 Ala mutation, found in the expression plasmid previously thought to encode the wild-type enzyme, increased the affinity for glucose by about 2.5-fold without changing the affinity for the regulatory protein. The mutations that were found to decrease the affinity for the regulatory protein (Asn166 Arg. Val203 Ala, Asn204 Gln, Lys414 Ala) clustered in the hinge region of glucokinase and nearby in the large and small domains. These results are in agreement with the concept that part of the binding site for the regulatory protein is situated in the hinge region of this enzyme.
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Affiliation(s)
- M Veiga-da-Cunha
- Laboratory of Physiological Chemistry, Institute of Cellular and Molecular Pathology, Brusscls, Belgium
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35
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Hsieh PC, Shenoy BC, Samols D, Phillips NF. Cloning, expression, and characterization of polyphosphate glucokinase from Mycobacterium tuberculosis. J Biol Chem 1996; 271:4909-15. [PMID: 8617763 DOI: 10.1074/jbc.271.9.4909] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Polyphosphate glucokinase from Mycobacterium tuberculosis catalyzes the phosphorylation of glucose using polyphosphate or ATP as the phosphoryl donor. The M. tuberculosis H37Rv gene encoding this enzyme has been cloned, sequenced, and expressed in Escherichia coli. The gene contains an open reading frame for 265 amino acids with a calculated mass of 27,400 daltons. The recombinant polyphosphate glucokinase was purified 189-fold to homogeneity and shown to contain dual enzymatic activities, similar to the native enzyme from H37Ra strain. The high G+C content in the codon usage (64.5%) of the gene and the absence of an E. coli-like promoter consensus sequence are consistent with other mycobacterial genes. Two phosphate binding domains conserved in the eukaryotic hexokinase family were identified in the polyphosphate glucokinase sequence, however, "adenosine" and "glucose" binding motifs were not apparent. In addition, a putative polyphosphate binding region is also proposed for the polyphosphate glucokinase enzyme.
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Affiliation(s)
- P C Hsieh
- Department of Biochemistry, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106-4935, USA
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36
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Roos MD, Han IO, Paterson AJ, Kudlow JE. Role of glucosamine synthesis in the stimulation of TGF-alpha gene transcription by glucose and EGF. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 270:C803-11. [PMID: 8638660 DOI: 10.1152/ajpcell.1996.270.3.c803] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Transforming growth factor-alpha (TGF-alpha) gene transcription is regulated by both epidermal growth factor (EGF) and glucose. Previous studies have suggested that the metabolism of glucose to glucosamine through the enzyme L-glutamine: D-fructose-6-phosphate amidotransferase (GFAT) plays a critical role in the glucose signaling. In this paper, we compared the role of GFAT in the glucose and EGF signals. We found that, although EGF stimulates GFAT mRNA accumulation in MDA-MB-468 cells, this effect of EGF occurred several hours after TGF-alpha transcription increased. MDA-MB-468 cells also exhibited a TGF-alpha transcriptional response to low concentrations of glucose. The TGF-alpha response to glucose but not EGF could be inhibited by a blocker of GFAT activity. Blockade of GFAT was confirmed by using Western blotting with the RL2 antibody, which recognizes an epitope on proteins containing N-acetylglucosamine. Exposure of cells to glucose increased the RL2 signal on several polypeptides, but this change could be blocked by inhibition of GFAT. These results support the notion that glucose stimulation of TGF-alpha expression requires GFAT, but EGF stimulation does not.
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Affiliation(s)
- M D Roos
- Division of Endocrinology and Metabolism, University of Alabama at Birmingham 35294, USA
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37
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Terauchi Y, Sakura H, Yasuda K, Iwamoto K, Takahashi N, Ito K, Kasai H, Suzuki H, Ueda O, Kamada N. Pancreatic beta-cell-specific targeted disruption of glucokinase gene. Diabetes mellitus due to defective insulin secretion to glucose. J Biol Chem 1995; 270:30253-6. [PMID: 8530440 DOI: 10.1074/jbc.270.51.30253] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Mice carrying a null mutation in the glucokinase (GK) gene in pancreatic beta-cells, but not in the liver, were generated by disrupting the beta-cell-specific exon. Heterozygous mutant mice showed early-onset mild diabetes due to impaired insulin-secretory response to glucose. Homozygotes showed severe diabetes shortly after birth and died within a week. GK-deficient islets isolated from homozygotes showed defective insulin secretion in response to glucose, while they responded to other secretagogues: almost normally to arginine and to some extent to sulfonylureas. These data provide the first direct proof that GK serves as a glucose sensor molecule for insulin secretion and plays a pivotal role in glucose homeostasis. GK-deficient mice serve as an animal model of the insulin-secretory defect in human non-insulin-dependent diabetes mellitus.
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Affiliation(s)
- Y Terauchi
- Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan
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38
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Lehto M, Huang X, Davis EM, Le Beau MM, Laurila E, Eriksson KF, Bell GI, Groop L. Human hexokinase II gene: exon-intron organization, mutation screening in NIDDM, and its relationship to muscle hexokinase activity. Diabetologia 1995; 38:1466-74. [PMID: 8786021 DOI: 10.1007/bf00400608] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In muscle, hexokinase II (HK2) regulates phosphorylation of glucose to glucose 6-phosphate, which has been reported to be impaired in patients with non-insulin-dependent diabetes mellitus (NIDDM). Here we report decreased HK2 enzyme activity in skeletal muscle biopsies from patients with impaired glucose tolerance compared with healthy control subjects (2.7 +/- 0.9 vs 4.9 +/- 1.1 nmol.min-1.mg protein-1). Therefore, mutations in the HK2 gene could contribute to skeletal muscle insulin resistance in NIDDM. To address this question, we first determined the exon-intron structure of the human HK2 gene and using this information, we screened all 18 exons with single-strand conformation polymorphism technique in 80 Finnish NIDDM patients. Nine nucleotide substitutions were found, one of which was a missense mutation (Gln142-His142) in exon 4. In human muscle, a single HK2 mRNA transcript with a size of approximately 5500 nucleotides was detected with Northern blot analysis. We also describe an HK2 pseudogene (HK2P1), which was mapped to chromosome 4, band q26, by fluorescence in situ hybridization to metaphase chromosomes. The clinical characteristics and HK2 enzyme activities of the subjects with either Gln or His at residue 142 did not differ from each other. Instead, HK2 activity correlated inversely with fasting blood glucose levels, suggesting that changes in HK2 activity could be secondary to other metabolic abnormalities (r = 0.55; p < 0.0003; n = 39). In conclusion; the data suggest that impaired HK2 activity in prediabetic individuals is a consequence of impaired glucose tolerance rather than of a genetic abnormality. The data thus seem to rule out mutations in the HK2 gene as a major cause of inherited insulin resistance in NIDDM.
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Affiliation(s)
- M Lehto
- Department of Biochemistry, University of Helsinki, Finland
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40
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Xu LZ, Harrison RW, Weber IT, Pilkis SJ. Human beta-cell glucokinase. Dual role of Ser-151 in catalysis and hexose affinity. J Biol Chem 1995; 270:9939-46. [PMID: 7730377 DOI: 10.1074/jbc.270.17.9939] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Glucokinase is distinguished from yeast hexokinase and low Km mammalian hexokinases by its low affinity for glucose and its cooperative behavior, even though glucose binding residues and catalytic residues are highly conserved in all of these forms of hexokinase. The roles of Ser-151 and Asn-166 as determinants of hexose affinity and cooperative behavior of human glucokinase have been evaluated by site-directed mutagenesis, expression and purification of the wild-type and mutant enzymes, and steady-state kinetic analysis. Mutation of Asn-166 to arginine increased apparent affinity for both glucose and ATP by a factor of 3. Mutation of Ser-151 to cysteine, alanine, or glycine lowered the Km for glucose by factors of 2-, 26-, and 40-fold, respectively, decreased Vmax, abolished cooperativity for glucose, and also decreased Km for mannose and fructose. The Ser-151 mutants had hexose Km values similar to those of yeast hexokinase, hexokinase I, and the recombinantly expressed COOH-terminal half of hexokinase I. However, the Ki values for the competitive inhibitors, N-acetylglucosamine and glucose-6-P, were unchanged, suggesting that Ser-151 is not important for inhibitor binding. Mutation of Ser-151 also increased the Km for ATP about 5-fold and abolished the enzyme's low ATPase activity, which indicates it is essential for ATP hydrolysis. The substrate-induced change in intrinsic fluorescence of S151A occurred at a much lower glucose concentration than that for wild-type enzyme. The results implicate a dual role for Ser-151 as a determinant of hexose affinity and catalysis, exclusive of the glucose-induced conformational change, and suggest that the low hexose affinity of glucokinase is dependent on interaction of Ser-151 with other regions of the protein.
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Affiliation(s)
- L Z Xu
- Department of Physiology and Biophysics, SUNY at Stony Brook 11794, USA
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42
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Site-directed mutagenesis studies on the determinants of sugar specificity and cooperative behavior of human beta-cell glucokinase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47007-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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