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Glycogen-Endoplasmic Reticulum Connection in the Liver. Int J Mol Sci 2023; 24:ijms24021074. [PMID: 36674588 PMCID: PMC9862463 DOI: 10.3390/ijms24021074] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/04/2022] [Accepted: 12/27/2022] [Indexed: 01/08/2023] Open
Abstract
Glycogen, the branched polymer of glucose is found mainly in the liver and muscle in mammals. Along with several other proteins, glycogen forms separate cellular organelles, and particles in cells. Glycogen particles in the liver have a special metabolic and also regulatory connection to the intracellular endomembrane system, particularly the endoplasmic reticulum. This connection is part of the organelle homeostasis in hepatocytes and forms a "glycogenoreticular system". The actual size of hepatic glycogen stores and the rate of glycogenolysis determines several essential liver-specific metabolic processes, such as glucose secretion for the maintenance of blood glucose levels or the glucuronidation of certain vital endo-, and xenobiotics, and are also related to liver antioxidant defense. In starvation, and in certain physiological and pathological states, where glycogen stores are depleted, functions of the glycogenoreticular system are altered. The starvation-induced depletion of hepatic glycogen content changes the biotransformation of various endo- and xenobiotics. This can be observed especially in acute DILI (drug-induced liver injury) due to paracetamol overdose, which is the most common cause of acute liver failure in the West.
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2
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Wang Z, Min X, Hu Z, Sullivan MA, Tang Y, Wang L, Gilbert RG, Shi C, Deng B. The fragility of liver glycogen from humans with type 2 diabetes: A pilot study. Int J Biol Macromol 2022; 221:83-90. [PMID: 36075306 DOI: 10.1016/j.ijbiomac.2022.08.212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/27/2022] [Accepted: 08/31/2022] [Indexed: 11/05/2022]
Abstract
Liver glycogen is a highly branched glucose polymer found as β particles (~20 nm in diameter), which can bind together into larger composite α particles. Hepatic α particles have been shown to be structurally fragile (breaking up into smaller particles in certain solvents) in mouse models of diabetes; if occurring in vivo, the resulting small glycogen particles could exacerbate the poor blood-sugar homeostasis characteristic of the disease. Here we tested if this α-particle fragility also occurred in liver glycogen obtained from humans with diabetes. It was found that liver glycogen from diabetic humans was indeed more fragile than from non-diabetic humans, which was also seen in the mouse experiments we ran in parallel. Proteomic analysis revealed three candidate proteins from differentially expressed glycogen proteins (Diabetes/ Non-diabetes) in both human and mouse groups. Identifying these proteins may give clues to the binding mechanism that holds together α particles together, which, being different in diabetic glycogen, is relevant to diabetes prevention and management.
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Affiliation(s)
- Ziyi Wang
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Xiaobo Min
- Department of Hepatobiliary Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Zhenxia Hu
- Department of Pharmacy, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, China
| | - Mitchell A Sullivan
- Glycation and Diabetes, Mater Research Institute - The University of Queensland, Translational Research Institute, Brisbane, QLD 4102, Australia
| | - Yong Tang
- Department of Hepatobiliary Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Liang Wang
- Laboratory Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong Province 510080, China
| | - Robert G Gilbert
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia; Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China
| | - Chen Shi
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| | - Bin Deng
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
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3
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Díaz-Lobo M, Fernández-Novell JM. Glycogen synthesis from dihydroxyacetone in isolated rat hepatocytes. J Carbohydr Chem 2021. [DOI: 10.1080/07328303.2021.1955129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Mireia Díaz-Lobo
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Josep Maria Fernández-Novell
- Faculty of Biology, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain
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4
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Brewer MK, Gentry MS. Brain Glycogen Structure and Its Associated Proteins: Past, Present and Future. ADVANCES IN NEUROBIOLOGY 2019; 23:17-81. [PMID: 31667805 PMCID: PMC7239500 DOI: 10.1007/978-3-030-27480-1_2] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This chapter reviews the history of glycogen-related research and discusses in detail the structure, regulation, chemical properties and subcellular distribution of glycogen and its associated proteins, with particular focus on these aspects in brain tissue.
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Affiliation(s)
- M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Center, Lafora Epilepsy Cure Initiative, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Center, Lafora Epilepsy Cure Initiative, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, USA.
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Bezborodkina NN, Chestnova AY, Vorobev ML, Kudryavtsev BN. Spatial Structure of Glycogen Molecules in Cells. BIOCHEMISTRY (MOSCOW) 2018; 83:467-482. [PMID: 29738682 DOI: 10.1134/s0006297918050012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Glycogen is a strongly branched polymer of α-D-glucose, with glucose residues in the linear chains linked by 1→4-bonds (~93% of the total number of bonds) and with branching after every 4-8 residues formed by 1→6-glycosidic bonds (~7% of the total number of bonds). It is thought currently that a fully formed glycogen molecule (β-particle) with the self-glycosylating protein glycogenin in the center has a spherical shape with diameter of ~42 nm and contains ~ 55,000 glucose residues. The glycogen molecule also includes numerous proteins involved in its synthesis and degradation, as well as proteins performing a carcass function. However, the type and force of bonds connecting these proteins to the polysaccharide moiety of glycogen are significantly different. This review presents the available data on the spatial structure of the glycogen molecule and its changes under various physiological and pathological conditions.
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Affiliation(s)
- N N Bezborodkina
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia.
| | - A Yu Chestnova
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
| | - M L Vorobev
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
| | - B N Kudryavtsev
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
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Assessment of fipronil toxicity on wistar rats: A hepatotoxic perspective. Toxicol Rep 2018; 5:448-456. [PMID: 29854616 PMCID: PMC5978010 DOI: 10.1016/j.toxrep.2018.02.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 02/06/2023] Open
Abstract
Fipronil was found to induce oxidative stress. Exposure to fipronil resulted in histopathology of hepatic tissue. Peak absorption changes in FT-IR was evident in liver of rats on Fipronil exposure. Fipronil modulated the enzymatic threshold of hepatic enzymes.
Extensive pesticide application has contributed to environmental contamination globally, imposing adverse health effects on non-target organisms. Need for an understanding of cellular response following pesticide exposure is, therefore, paradigmatic for elucidating perturbations occurring within biological systems. The present investigation was aimed to examine safe and toxic dose level of a persistent, synthetic, phenylpyrazole based insecticide, Fipronil (FPN) on rat liver. Experimental animals were divided into four groups and gavaged with 0.0 (control), 32.33 (high), 12.12 (medium) and 6.46 mg/kg body weight/day (low dose) of FPN for 90 days. While results for liver catalase and glutathione S-transferase indicated significant changes in high and medium dose groups, the superoxide dismutase and glutathione peroxidase activity suggested significant changes in all exposed groups as compared to control. Elevated levels of liver malondialdehyde reflected oxidative damage potential under the exposed groups but remained insignificant for low dose. Histologically, structural irregularities with findings like impaired portal vein and hypertrophy of hepatocytes were prominent under all the exposed groups. The FT-IR based spectral investigation further revealed changes in absorption patterns and peak intensities in rats exposed to FPN. Significant elevation was also noticed in liver enzymes; alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase in rat serum suggesting the toxicity in dose -dependent pattern. Based on the outcome, it could be ascertained that the toxicity of FPN is certain at high and medium dose levels but remains ambiguous at a low dose of 6.46 mg/kg body weight/day. The current upshots serve as a preliminary report thereby advising the farming community against the usage of FPN insecticide.
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7
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Biological characterization of a novel hybrid copolymer carrier system based on glycogen. Drug Deliv Transl Res 2017; 8:73-82. [DOI: 10.1007/s13346-017-0436-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Fernández-Novell JM, Díaz-Lobo M. Immunochemical Study of the Effect of F 2Glc on Glycogen Synthase Translocation and Glycogen Synthesis in Isolated Rat Hepatocytes. Appl Biochem Biotechnol 2017; 184:909-918. [PMID: 28918449 DOI: 10.1007/s12010-017-2597-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 09/06/2017] [Indexed: 10/18/2022]
Abstract
The compound 2-deoxy-2-fluoro-α-D-glucopyranosyl fluoride (F2Glc), which is a nonmetabolized superior glucose analogue, is a potent inhibitor of glycogen phosphorylase and pharmacological properties are reported. Glycogen phosphorylase (GP) and glycogen synthase (GS) are responsible of the degradation and synthesis, respectively, of glycogen which is a polymer of glucose units that provides a readily available source of energy in mammals. GP and GS are two key enzymes that modulate cellular glucose and glycogen levels; therefore, these proteins are suggested as potential targets for the treatment of diseases related to glycogen metabolism disorders. We studied by Western Blot technique that F2Glc decreased GP activity, and we also showed that F2Glc did not affect GS activity and its translocation from a uniform cytosolic distribution to the hepatocyte periphery, which is crucial for glycogen synthesis, using immunoblotting and immunofluorescence labeling techniques. F2Glc specifically inhibits glycogenolysis pathway and permits a greater deposition of glycogen. These observations open up the possibility of further develop drugs that act specifically on GP. The ability to selectively inhibit GP, which is a key enzyme for the release of glucose from the hepatic glycogen reserve, may represent a new approach for the treatment of hyperglycemia in type 2 diabetes.
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Affiliation(s)
- J M Fernández-Novell
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Avda. Diagonal 643, Edifici Prevosti, Planta (-2), 08028, Barcelona, Spain.
| | - M Díaz-Lobo
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
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9
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Imaging liver and brain glycogen metabolism at the nanometer scale. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 11:239-45. [PMID: 25262580 DOI: 10.1016/j.nano.2014.09.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 08/04/2014] [Accepted: 09/12/2014] [Indexed: 11/20/2022]
Abstract
In mammals, glycogen synthesis and degradation are dynamic processes regulating blood and cerebral glucose-levels within a well-defined physiological range. Despite the essential role of glycogen in hepatic and cerebral metabolism, its spatiotemporal distribution at the molecular and cellular level is unclear. By correlating electron microscopy and ultra-high resolution ion microprobe (NanoSIMS) imaging of tissue from fasted mice injected with (13)C-labeled glucose, we demonstrate that liver glycogenesis initiates in the hepatocyte perinuclear region before spreading toward the cell membrane. In the mouse brain, we observe that (13)C is inhomogeneously incorporated into astrocytic glycogen at a rate ~25 times slower than in the liver, in agreement with prior bulk studies. This experiment, using temporally resolved, nanometer-scale imaging of glycogen synthesis and degradation, provides greater insight into glucose metabolism in mammalian organs and shows how this technique can be used to explore biochemical pathways in healthy and diseased states.
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10
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Zhai J, Pan T, Zhu J, Xu Y, Chen J, Xie Y, Qin Y. Boronic Acid Functionalized Boron Dipyrromethene Fluorescent Probes: Preparation, Characterization, and Saccharides Sensing Applications. Anal Chem 2012; 84:10214-20. [DOI: 10.1021/ac301456s] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jingying Zhai
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
| | - Ting Pan
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
| | - Jingwei Zhu
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
| | - Yanmei Xu
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
| | - Juan Chen
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
| | - Yuanjie Xie
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
| | - Yu Qin
- State Key Laboratory of Analytical Chemistry
for Life
Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China, 210093
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11
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Nielsen J, Krustrup P, Nybo L, Gunnarsson TP, Madsen K, Schrøder HD, Bangsbo J, Ortenblad N. Skeletal muscle glycogen content and particle size of distinct subcellular localizations in the recovery period after a high-level soccer match. Eur J Appl Physiol 2012; 112:3559-67. [PMID: 22323299 DOI: 10.1007/s00421-012-2341-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Accepted: 01/27/2012] [Indexed: 10/14/2022]
Abstract
Whole muscle glycogen levels remain low for a prolonged period following a soccer match. The present study was conducted to investigate how this relates to glycogen content and particle size in distinct subcellular localizations. Seven high-level male soccer players had a vastus lateralis muscle biopsy collected immediately after and 24, 48, 72 and 120 h after a competitive soccer match. Transmission electron microscopy was used to estimate the subcellular distribution of glycogen and individual particle size. During the first day of recovery, glycogen content increased by ~60% in all subcellular localizations, but during the subsequent second day of recovery glycogen content located within the myofibrils (Intramyofibrillar glycogen, a minor deposition constituting 10-15% of total glycogen) did not increase further compared with an increase in subsarcolemmal glycogen (-7 vs. +25%, respectively, P = 0.047). Conversely, from the second to the fifth day of recovery, glycogen content increased (53%) within the myofibrils compared to no change in subsarcolemmal or intermyofibrillar glycogen (P < 0.005). Independent of location, increment in particle size preceded increment in number of particles. Intriguingly, average particle size decreased; however, in the period from 3 to 5 days after the match. These findings suggest that glycogen storage in skeletal muscle is influenced by subcellular localization-specific mechanisms, which account for an increase in number of glycogen particles located within the myofibrils in the period from 2 to 5 days after the soccer match.
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Affiliation(s)
- Joachim Nielsen
- Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, 5230 Odense M, Denmark.
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12
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Stapleton D, Nelson C, Parsawar K, McClain D, Gilbert-Wilson R, Barker E, Rudd B, Brown K, Hendrix W, O’Donnell P, Parker G. Analysis of hepatic glycogen-associated proteins. Proteomics 2010; 10:2320-9. [PMID: 20391537 PMCID: PMC2892038 DOI: 10.1002/pmic.200900628] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Accepted: 03/24/2010] [Indexed: 12/25/2022]
Abstract
Glycogen particles are associated with a population of proteins that mediate its biological functions, including: management of glucose flux into and out of the glycogen particle, maintenance of glycogen structure and regulation of particle size, number, and cellular location. A survey of the glycogen-associated proteome would be predicted to identify the relative representation of known members of this population, and associations with unexpected proteins that have the potential to mediate other functions of the glycogen particle. We therefore purified glycogen particles from both mouse and rat liver, using different techniques, and analyzed the resulting tryptic peptides by MS. We also specifically eluted glycogen-binding proteins from the pellet using malto-oligosaccharides. Comparison of the rat and mouse populations, and analysis of specifically eluted proteins allow some conclusions to be made about the hepatic glycogen sub-proteome. With the exception of glycogen branching enzyme all glycogen metabolic proteins were detected. Novel associations were identified, including ferritin and starch-binding domain protein 1, a protein that contains both a transmembrane endoplasmic reticulum signal peptide and a carbohydrate-binding module. This study therefore provides insight into the organization of the glycogen proteome, identifies other associated proteins and provides a starting point to explore the dynamic nature and cellular distribution of this metabolically important protein population.
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Affiliation(s)
- David Stapleton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Chad Nelson
- University of Utah, Mass Spectrometry and Proteomics Core Facility, University of Utah, Salt Lake City, Utah, 84132, USA
| | - Krishna Parsawar
- University of Utah, Mass Spectrometry and Proteomics Core Facility, University of Utah, Salt Lake City, Utah, 84132, USA
| | - Donald McClain
- Department of Medicine, Division of Endocrinology, University of Utah School of Medicine, Salt Lake City, Utah, 84132, USA
| | - Ryan Gilbert-Wilson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Elizabeth Barker
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Brant Rudd
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Kevin Brown
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Wayne Hendrix
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Paul O’Donnell
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Glendon Parker
- Department of Medicine, Division of Endocrinology, University of Utah School of Medicine, Salt Lake City, Utah, 84132, USA
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
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Ros S, García-Rocha M, Domínguez J, Ferrer JC, Guinovart JJ. Control of Liver Glycogen Synthase Activity and Intracellular Distribution by Phosphorylation. J Biol Chem 2009; 284:6370-8. [DOI: 10.1074/jbc.m808576200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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14
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Jurczak MJ, Danos AM, Rehrmann VR, Brady MJ. The role of protein translocation in the regulation of glycogen metabolism. J Cell Biochem 2008; 104:435-43. [DOI: 10.1002/jcb.21634] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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15
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Louzao MC, Espiña B, Vieytes MR, Vega FV, Rubiolo JA, Baba O, Terashima T, Botana LM. "Fluorescent glycogen" formation with sensibility for in vivo and in vitro detection. Glycoconj J 2007; 25:503-10. [PMID: 17973187 DOI: 10.1007/s10719-007-9075-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 09/13/2007] [Accepted: 09/26/2007] [Indexed: 12/31/2022]
Abstract
There are presently many methods of detecting complex carbohydrates, and particularly glycogen. However most of them require radioisotopes or destruction of the tissue and hydrolysis of glycogen to glucose. Here we present a new method based on the incorporation of 2-NBDG (2-{N-[7-nitrobenz-2-oxa-1, 3-diazol 4-yl] amino}-2-deoxyglucose), a D-glucose fluorescent derivative, into glycogen. Two kinds of approaches were carried out by using Clone 9 rat hepatocytes as a cellular model; (1) Incubation of cell lysates with 2-NBDG, carbohydrate precipitation in filters and measurement of fluorescence in a microplate reader (2) Incubation of living hepatocytes with 2-NBDG and recording of fluorescence images by confocal microscopy. 2-NBDG labeled glycogen in both approaches. We confirmed this fact by comparison to the labeling obtained with a specific monoclonal anti-glycogen antibody. Also drugs that trigger glycogen synthesis or degradation induced an increase or decrease of fluorescence, respectively. This is a simple but efficient method of detecting glycogen with 2-NBDG. It could be used to record changes in glycogen stores in living cells and cell-free systems and opens the prospect of understanding the role of this important energy reserve under various physiological and pathophysiological conditions.
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Affiliation(s)
- M Carmen Louzao
- Departamento de Farmacologia, Facultad de Veterinaria de Lugo, Universidad de Santiago de Compostela, 27002 Lugo, Spain.
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Fernández-Novell JM, Rodríguez-Gil JE, Barberà A, Guinovart JJ. Lithium ions increase hepatic glycogen synthase stability through a proteasome-related mechanism. Arch Biochem Biophys 2007; 457:29-34. [PMID: 17125726 DOI: 10.1016/j.abb.2006.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 10/06/2006] [Accepted: 10/12/2006] [Indexed: 11/18/2022]
Abstract
Incubation of rat hepatocytes with LiCl resulted in an overall increase in the activity ratio of glycogen synthase (GS), concomitantly with a decrease in active GS kinase-3 levels. GS total activity was also increased in a dose- and time-dependent manner. This latter effect correlated with the amount of immunoreactive enzyme determined by immunoblotting. Cycloheximide and actinomycin-D did not modify LiCl action on GS activity. Lithium ions did not induce any changes in GS mRNA levels. Furthermore, the increase in the total amount of GS induced by LiCl was further augmented after addition of a specific, calpain and proteasome inhibitor. Our results indicate that LiCl increases hepatocyte GS activity through increasing both the activation state of the enzyme and its cellular content. This latter increase is mediated through a modification of the proteasome-regulated proteolytic pathway of the enzyme.
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Affiliation(s)
- Josep M Fernández-Novell
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Avgda. Diagonal 645, Edifici nou planta-1, E-08028 Barcelona, Spain.
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17
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Wilson WA, Skurat AV, Probst B, de Paoli-Roach A, Roach PJ, Rutter J. Control of mammalian glycogen synthase by PAS kinase. Proc Natl Acad Sci U S A 2005; 102:16596-601. [PMID: 16275910 PMCID: PMC1283851 DOI: 10.1073/pnas.0508481102] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The regulation of glycogen metabolism is critical for the maintenance of glucose and energy homeostasis in mammals. Glycogen synthase, the enzyme responsible for glycogen production, is regulated by multisite phosphorylation in yeast and mammals. We have previously identified PAS kinase as a physiological regulator of glycogen synthase in Saccharomyces cerevisiae. We provide evidence here that PAS kinase is an important regulator of mammalian glycogen synthase. Glycogen synthase is efficiently phosphorylated by PAS kinase in vitro at Ser-640, a known regulatory phosphosite. Efficient phosphorylation requires a region of PAS kinase outside the catalytic domain. This region appears to mediate a direct interaction between glycogen synthase and PAS kinase, thereby targeting kinase activity to this substrate specifically. This interaction is regulated by the PAS kinase PAS domain, raising the possibility that this interaction (and phosphorylation event) is modulated by the cellular metabolic state. This mode of regulation provides a mechanism for metabolic status to impinge directly on the cellular decision of whether to store or use available energy.
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Affiliation(s)
- Wayne A Wilson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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18
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Cid E, Cifuentes D, Baqué S, Ferrer JC, Guinovart JJ. Determinants of the nucleocytoplasmic shuttling of muscle glycogen synthase. FEBS J 2005; 272:3197-213. [PMID: 15955076 DOI: 10.1111/j.1742-4658.2005.04738.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Muscle glycogen synthase (MGS) presents a nuclear speckled pattern in primary cultured human muscle and in 3T3-L1 cells deprived of glucose and with depleted glycogen reserves. Nuclear accumulation of the enzyme correlates inversely with cellular glycogen content. Although the glucose-induced export of MGS from the nucleus to the cytoplasm is blocked by leptomycin B, and therefore mediated by CRM1, no nuclear export signal was identified in the sequence of the protein. Deletion analysis shows that the region comprising amino acids 555-633 of human MGS, which encompasses an Arg-rich cluster involved in the allosteric activation of the enzyme by Glc6P, is crucial for its nuclear concentration and aggregation. Mutation of these Arg residues, which desensitizes the enzyme towards Glc6P, interferes with its nuclear accumulation. In contrast, the known phosphorylation sites of MGS that regulate its activity are not involved in the control of its subcellular distribution. Nuclear human MGS co-localizes with the promyelocytic leukaemia oncoprotein and p80-coilin, a marker of Cajal bodies. The subnuclear distribution of MGS is altered by incubation with transcription inhibitors. These observations suggest that, in addition to its metabolic function, MGS may participate in nuclear processes.
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Affiliation(s)
- Emili Cid
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Spain
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Yáñez AJ, Bertinat R, Concha II, Slebe JC. Nuclear localization of liver FBPase isoenzyme in kidney and liver. FEBS Lett 2003; 550:35-40. [PMID: 12935882 DOI: 10.1016/s0014-5793(03)00809-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Nuclear localization has been observed for glycolytic enzymes but not for key gluconeogenic enzymes. We report our findings on the intracellular localization of liver FBPase in rat liver and kidney, the main organs in the endogenous glucose production. Immunofluorescence and confocal analysis revealed that FBPase was present in the cytosol and, unexpectedly, inside the nucleus of hepatocytes and proximal cells of the nephron. Additionally, FBPase was found in the plasma membrane area of adjacent hepatocytes where glycogen is synthesized and in the apical region of proximal kidney cells. This subcellular distribution in multiple compartments suggests the presence of different localization signals on FBPase for diverse metabolic functions.
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Affiliation(s)
- Alejandro J Yáñez
- Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
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20
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Yánez AJ, Nualart F, Droppelmann C, Bertinat R, Brito M, Concha II, Slebe JC. Broad expression of fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase provide evidence for gluconeogenesis in human tissues other than liver and kidney. J Cell Physiol 2003; 197:189-97. [PMID: 14502558 DOI: 10.1002/jcp.10337] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The importance of renal and hepatic gluconeogenesis in glucose homeostasis is well established, but the cellular localization of the key gluconeogenic enzymes liver fructose-1,6-bisphosphatase (FBPase) and cytosolic phosphoenolpyruvate carboxykinase (PEPCK) in these organs and the potential contribution of other tissues in this process has not been investigated in detail. Therefore, we analyzed the human tissue localization and cellular distribution of FBPase and PEPCK immunohistochemically. The localization analysis demonstrated that FBPase was expressed in many tissues that had not been previously reported to contain FBPase activity (e.g., prostate, ovary, suprarenal cortex, stomach, and heart). In some multicellular tissues, this enzyme was detected in specialized areas such as epithelial cells of the small intestine and prostate or lung pneumocytes II. Interestingly, FBPase was also present in pancreas and cortex cells of the adrenal gland, organs that are involved in the control of carbohydrate and lipid metabolism. Although similar results were obtained for PEPCK localization, different expression of this enzyme was observed in pancreas, adrenal gland, and pneumocytes type I. These results show that co-expression of FBPase and PEPCK occurs not only in kidney and liver, but also in a variety of organs such as the small intestine, stomach, adrenal gland, testis, and prostate which might also contribute to gluconeogenesis. Our results are consistent with published data on the expression of glucose-6-phosphatase in the human small intestine, providing evidence that this organ may play an important role in the human glucose homeostasis.
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Affiliation(s)
- Alejandro J Yánez
- Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
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Ferrer JC, Favre C, Gomis RR, Fernández-Novell JM, García-Rocha M, de la Iglesia N, Cid E, Guinovart JJ. Control of glycogen deposition. FEBS Lett 2003; 546:127-32. [PMID: 12829248 DOI: 10.1016/s0014-5793(03)00565-9] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Traditionally, glycogen synthase (GS) has been considered to catalyze the key step of glycogen synthesis and to exercise most of the control over this metabolic pathway. However, recent advances have shown that other factors must be considered. Moreover, the control of glycogen deposition does not follow identical mechanisms in muscle and liver. Glucose must be phosphorylated to promote activation of GS. Glucose-6-phosphate (Glc-6-P) binds to GS, causing the allosteric activation of the enzyme probably through a conformational rearrangement that simultaneously converts it into a better substrate for protein phosphatases, which can then lead to the covalent activation of GS. The potency of Glc-6-P for activation of liver GS is determined by its source, since Glc-6-P arising from the catalytic action of glucokinase (GK) is much more effective in mediating the activation of the enzyme than the same metabolite produced by hexokinase I (HK I). As a result, hepatic glycogen deposition from glucose is subject to a system of control in which the 'controller', GS, is in turn controlled by GK. In contrast, in skeletal muscle, the control of glycogen synthesis is shared between glucose transport and GS. The characteristics of the two pairs of isoenzymes, liver GS/GK and muscle GS/HK I, and the relationships that they establish are tailored to suit specific metabolic roles of the tissues in which they are expressed. The key enzymes in glycogen metabolism change their intracellular localization in response to glucose. The changes in the intracellular distribution of liver GS and GK triggered by glucose correlate with stimulation of glycogen synthesis. The translocation of GS, which constitutes an additional mechanism of control, causes the orderly deposition of hepatic glycogen and probably represents a functional advantage in the metabolism of the polysaccharide.
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Affiliation(s)
- Juan C Ferrer
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, 08028 Barcelona, Spain
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22
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Gomis RR, Favre C, García-Rocha M, Fernández-Novell JM, Ferrer JC, Guinovart JJ. Glucose 6-phosphate produced by gluconeogenesis and by glucokinase is equally effective in activating hepatic glycogen synthase. J Biol Chem 2003; 278:9740-6. [PMID: 12519761 DOI: 10.1074/jbc.m212151200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucose 6-phosphate (Glc-6-P) produced in cultured hepatocytes by direct phosphorylation of glucose or by gluconeogenesis from dihydroxyacetone (DHA) was equally effective in activating glycogen synthase (GS). However, glycogen accumulation was higher in hepatocytes incubated with glucose than in those treated with DHA. This difference was attributed to decreased futile cycling through GS and glycogen phosphorylase (GP) in the glucose-treated hepatocytes, owing to the partial inactivation of GP induced by glucose. Our results indicate that the gluconeogenic pathway and the glucokinase-mediated phosphorylation of glucose deliver their common product to the same Glc-6-P pool, which is accessible to liver GS. As observed in the treatment with glucose, incubation of cultured hepatocytes with DHA caused the translocation of GS from a uniform cytoplasmic distribution to the hepatocyte periphery and a similar pattern of glycogen deposition. We hypothesize that Glc-6-P has a major role in glycogen metabolism not only by determining the activation state of GS but also by controlling its subcellular distribution in the hepatocyte.
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Affiliation(s)
- Roger R Gomis
- Departament de Bioquimica i Biologia Molecular and the Institut de Recerca Biomèdica de Barcelona-Parc Cientific de Barcelona, Universitat de Barcelona, Barcelona E-08028, Spain
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