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Llavero F, Zugaza JL. The importance of muscle glycogen phosphorylase in glial cells function. Biochem Soc Trans 2024; 52:1265-1274. [PMID: 38661212 DOI: 10.1042/bst20231058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/26/2024]
Abstract
The three isoforms of glycogen phosphorylase - PYGM, PYGB, and PYGL - are expressed in glial cells. Unlike PYGB and PYGL, PYGM is the only isoform regulated by Rac1. This specific regulation may confer a differential functional role compared with the other glycogen phosphorylases-PYGB and PYGL. The involvement of muscle glycogen phosphorylase in glial cells and its association with post-translational modifications (PTMs) of proteins through O-glycosylation is indeed a fascinating and emerging area of research. The dual role it plays in metabolic processes and the regulation of PTMs within the brain presents intriguing implications for various neurological conditions. Disruptions in the O-GlcNAcylation cycle and neurodegenerative diseases like Alzheimer's disease (AD) is particularly noteworthy. The alterations in O-GlcNAcylation levels of specific proteins, such as APP, c-Fos, and tau protein, highlight the intricate relationship between PTMs and AD. Understanding these processes and the regulatory function of muscle glycogen phosphorylase sheds light on its impact on protein function, signaling pathways, cellular homeostasis, neurological health, and potential interventions for brain-related conditions.
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Affiliation(s)
- Francisco Llavero
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Sede Building, 3rd Floor, Barrio de Sarriena s/n, 48940 Leioa, Spain
| | - José L Zugaza
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Sede Building, 3rd Floor, Barrio de Sarriena s/n, 48940 Leioa, Spain
- Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, UPV/EHU, Barrio de Sarriena s/n, 48940 Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain
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2
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Hu Y, Hruscha A, Pan C, Schifferer M, Schmidt MK, Nuscher B, Giera M, Kostidis S, Burhan Ö, van Bebber F, Edbauer D, Arzberger T, Haass C, Schmid B. Mis-localization of endogenous TDP-43 leads to ALS-like early-stage metabolic dysfunction and progressive motor deficits. Mol Neurodegener 2024; 19:50. [PMID: 38902734 PMCID: PMC11188230 DOI: 10.1186/s13024-024-00735-7] [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: 11/22/2023] [Accepted: 05/23/2024] [Indexed: 06/22/2024] Open
Abstract
BACKGROUND The key pathological signature of ALS/ FTLD is the mis-localization of endogenous TDP-43 from the nucleus to the cytoplasm. However, TDP-43 gain of function in the cytoplasm is still poorly understood since TDP-43 animal models recapitulating mis-localization of endogenous TDP-43 from the nucleus to the cytoplasm are missing. METHODS CRISPR/Cas9 technology was used to generate a zebrafish line (called CytoTDP), that mis-locates endogenous TDP-43 from the nucleus to the cytoplasm. Phenotypic characterization of motor neurons and the neuromuscular junction was performed by immunostaining, microglia were immunohistochemically localized by whole-mount tissue clearing and muscle ultrastructure was analyzed by scanning electron microscopy. Behavior was investigated by video tracking and quantitative analysis of swimming parameters. RNA sequencing was used to identify mis-regulated pathways with validation by molecular analysis. RESULTS CytoTDP fish have early larval phenotypes resembling clinical features of ALS such as progressive motor defects, neurodegeneration and muscle atrophy. Taking advantage of zebrafish's embryonic development that solely relys on yolk usage until 5 days post fertilization, we demonstrated that microglia proliferation and activation in the hypothalamus is independent from food intake. By comparing CytoTDP to a previously generated TDP-43 knockout line, transcriptomic analyses revealed that mis-localization of endogenous TDP-43, rather than TDP-43 nuclear loss of function, leads to early onset metabolic dysfunction. CONCLUSIONS The new TDP-43 model mimics the ALS/FTLD hallmark of progressive motor dysfunction. Our results suggest that functional deficits of the hypothalamus, the metabolic regulatory center, might be the primary cause of weight loss in ALS patients. Cytoplasmic gain of function of endogenous TDP-43 leads to metabolic dysfunction in vivo that are reminiscent of early ALS clinical non-motor metabolic alterations. Thus, the CytoTDP zebrafish model offers a unique opportunity to identify mis-regulated targets for therapeutic intervention early in disease progression.
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Affiliation(s)
- Yiying Hu
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
- Metabolic Biochemistry, Biomedical Centre (BMC), Faculty of Medicine, Ludwig-Maximilian University, Munich, Germany
- Munich Medical Research School (MMRS), Munich, Germany
| | - Alexander Hruscha
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
| | - Chenchen Pan
- Neurology Clinic and National Center for Tumor Diseases, Heidelberg University Hospital, Heidelberg, Germany
- Clinical Cooperation Unit Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martina Schifferer
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Michael K Schmidt
- Zentrum Für Neuropathologie, Ludwig-Maximilians University, Munich, Germany
| | - Brigitte Nuscher
- Metabolic Biochemistry, Biomedical Centre (BMC), Faculty of Medicine, Ludwig-Maximilian University, Munich, Germany
| | - Martin Giera
- Leiden University Medical Center, Leiden, Netherlands
| | | | - Özge Burhan
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
| | - Frauke van Bebber
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
| | - Dieter Edbauer
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
- Metabolic Biochemistry, Biomedical Centre (BMC), Faculty of Medicine, Ludwig-Maximilian University, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Thomas Arzberger
- Zentrum Für Neuropathologie, Ludwig-Maximilians University, Munich, Germany
- Department of Psychiatry and Psychotherapy, University Hospital, Ludwig-Maximilians University, Munich, Germany
| | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
- Metabolic Biochemistry, Biomedical Centre (BMC), Faculty of Medicine, Ludwig-Maximilian University, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Bettina Schmid
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.
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Duran J. Role of Astrocytes in the Pathophysiology of Lafora Disease and Other Glycogen Storage Disorders. Cells 2023; 12:cells12050722. [PMID: 36899857 PMCID: PMC10000527 DOI: 10.3390/cells12050722] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/05/2023] [Accepted: 02/22/2023] [Indexed: 03/12/2023] Open
Abstract
Lafora disease is a rare disorder caused by loss of function mutations in either the EPM2A or NHLRC1 gene. The initial symptoms of this condition are most commonly epileptic seizures, but the disease progresses rapidly with dementia, neuropsychiatric symptoms, and cognitive deterioration and has a fatal outcome within 5-10 years after onset. The hallmark of the disease is the accumulation of poorly branched glycogen in the form of aggregates known as Lafora bodies in the brain and other tissues. Several reports have demonstrated that the accumulation of this abnormal glycogen underlies all the pathologic traits of the disease. For decades, Lafora bodies were thought to accumulate exclusively in neurons. However, it was recently identified that most of these glycogen aggregates are present in astrocytes. Importantly, astrocytic Lafora bodies have been shown to contribute to pathology in Lafora disease. These results identify a primary role of astrocytes in the pathophysiology of Lafora disease and have important implications for other conditions in which glycogen abnormally accumulates in astrocytes, such as Adult Polyglucosan Body disease and the buildup of Corpora amylacea in aged brains.
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Affiliation(s)
- Jordi Duran
- Institut Químic de Sarrià (IQS), Universitat Ramon Llull (URL), 08017 Barcelona, Spain;
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
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4
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Ibrahim MMH, Bheemanapally K, Sylvester PW, Briski KP. Norepinephrine Regulation of Adrenergic Receptor Expression, 5' AMP-Activated Protein Kinase Activity, and Glycogen Metabolism and Mass in Male Versus Female Hypothalamic Primary Astrocyte Cultures. ASN Neuro 2021; 12:1759091420974134. [PMID: 33176438 PMCID: PMC7672765 DOI: 10.1177/1759091420974134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Norepinephrine (NE) control of hypothalamic gluco-regulation involves astrocyte-derived energy fuel supply. In male rats, exogenous NE regulates astrocyte glycogen metabolic enzyme expression in vivo through 5’-AMP-activated protein kinase (AMPK)-dependent mechanisms. Current research utilized a rat hypothalamic astrocyte primary culture model to investigate the premise that NE imposes sex-specific direct control of AMPK activity and glycogen mass and metabolism in these glia. In male rats, NE down-regulation of pAMPK correlates with decreased CaMMKB and increased PP1 expression, whereas noradrenergic augmentation of female astrocyte pAMPK may not involve these upstream regulators. NE concentration is a critical determinant of control of hypothalamic astrocyte glycogen enzyme expression, but efficacy varies between sexes. Data show sex variations in glycogen synthase expression and glycogen phosphorylase-brain and –muscle type dose-responsiveness to NE. Narrow dose-dependent NE augmentation of astrocyte glycogen content during energy homeostasis infers that NE maintains, over a broad exposure range, constancy of glycogen content despite possible changes in turnover. In male rats, beta1- and beta2-adrenergic receptor (AR) profiles displayed bi-directional responses to increasing NE doses; female astrocytes exhibited diminished beta1-AR content at low dose exposure, but enhanced beta2-AR expression at high NE dosages. Thus, graded variations in noradrenergic stimulation may modulate astrocyte receptivity to NE in vivo. Sex dimorphic NE regulation of hypothalamic astrocyte AMPK activation and glycogen metabolism may be mediated, in part, by one or more ARs characterized here by divergent sensitivity to this transmitter.
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Affiliation(s)
- Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
| | - Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
| | - Paul W Sylvester
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
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5
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McArdle Disease: New Insights into Its Underlying Molecular Mechanisms. Int J Mol Sci 2019; 20:ijms20235919. [PMID: 31775340 PMCID: PMC6929006 DOI: 10.3390/ijms20235919] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/14/2019] [Accepted: 11/21/2019] [Indexed: 01/05/2023] Open
Abstract
McArdle disease, also known as glycogen storage disease type V (GSDV), is characterized by exercise intolerance, the second wind phenomenon, and high serum creatine kinase activity. Here, we recapitulate PYGM mutations in the population responsible for this disease. Traditionally, McArdle disease has been considered a metabolic myopathy caused by the lack of expression of the muscle isoform of the glycogen phosphorylase (PYGM). However, recent findings challenge this view, since it has been shown that PYGM is present in other tissues than the skeletal muscle. We review the latest studies about the molecular mechanism involved in glycogen phosphorylase activity regulation. Further, we summarize the expression and functional significance of PYGM in other tissues than skeletal muscle both in health and McArdle disease. Furthermore, we examine the different animal models that have served as the knowledge base for better understanding of McArdle disease. Finally, we give an overview of the latest state-of-the-art clinical trials currently being carried out and present an updated view of the current therapies.
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6
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Soares AF, Nissen JD, Garcia‐Serrano AM, Nussbaum SS, Waagepetersen HS, Duarte JMN. Glycogen metabolism is impaired in the brain of male type 2 diabetic Goto‐Kakizaki rats. J Neurosci Res 2019; 97:1004-1017. [DOI: 10.1002/jnr.24437] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Ana Francisca Soares
- Laboratory for Functional and Metabolic Imaging École Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Jakob D. Nissen
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology University of Copenhagen Copenhagen Denmark
| | - Alba M. Garcia‐Serrano
- Faculty of Medicine, Department of Experimental Medical Science Lund University Lund Sweden
- Wallenberg Centre for Molecular Medicine Lund University Lund Sweden
| | - Sakura S. Nussbaum
- Laboratory for Functional and Metabolic Imaging École Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Helle S. Waagepetersen
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology University of Copenhagen Copenhagen Denmark
| | - João M. N. Duarte
- Laboratory for Functional and Metabolic Imaging École Polytechnique Fédérale de Lausanne Lausanne Switzerland
- Faculty of Medicine, Department of Experimental Medical Science Lund University Lund Sweden
- Wallenberg Centre for Molecular Medicine Lund University Lund Sweden
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7
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Glycogenolysis in Cerebral Cortex During Sensory Stimulation, Acute Hypoglycemia, and Exercise: Impact on Astrocytic Energetics, Aerobic Glycolysis, and Astrocyte-Neuron Interactions. ADVANCES IN NEUROBIOLOGY 2019; 23:209-267. [DOI: 10.1007/978-3-030-27480-1_8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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8
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Dienel GA, Carlson GM. Major Advances in Brain Glycogen Research: Understanding of the Roles of Glycogen Have Evolved from Emergency Fuel Reserve to Dynamic, Regulated Participant in Diverse Brain Functions. ADVANCES IN NEUROBIOLOGY 2019; 23:1-16. [DOI: 10.1007/978-3-030-27480-1_1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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9
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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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10
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Bak LK, Walls AB, Schousboe A, Waagepetersen HS. Astrocytic glycogen metabolism in the healthy and diseased brain. J Biol Chem 2018; 293:7108-7116. [PMID: 29572349 DOI: 10.1074/jbc.r117.803239] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The brain contains a fairly low amount of glycogen, mostly located in astrocytes, a fact that has prompted the suggestion that glycogen does not have a significant physiological role in the brain. However, glycogen metabolism in astrocytes is essential for several key physiological processes and is adversely affected in disease. For instance, diminished ability to break down glycogen impinges on learning, and epilepsy, Alzheimer's disease, and type 2 diabetes are all associated with abnormal astrocyte glycogen metabolism. Glycogen metabolism supports astrocytic K+ and neurotransmitter glutamate uptake and subsequent glutamine synthesis-three fundamental steps in excitatory signaling at most brain synapses. Thus, there is abundant evidence for a key role of glycogen in brain function. Here, we summarize the physiological brain functions that depend on glycogen, discuss glycogen metabolism in disease, and investigate how glycogen breakdown is regulated at the cellular and molecular levels.
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Affiliation(s)
- Lasse K Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark.
| | - Anne B Walls
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
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11
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Carlson GM, Dienel GA, Colbran RJ. Introduction to the Thematic Minireview Series: Brain glycogen metabolism. J Biol Chem 2018. [PMID: 29514979 DOI: 10.1074/jbc.tm118.002642] [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] [Indexed: 01/10/2023] Open
Abstract
The synthesis of glycogen allows for efficient intracellular storage of glucose molecules in a soluble form that can be rapidly released to enter glycolysis in response to energy demand. Intensive studies of glucose and glycogen metabolism, predominantly in skeletal muscle and liver, have produced innumerable insights into the mechanisms of hormone action, resulting in the award of several Nobel Prizes over the last one hundred years. Glycogen is actually present in all cells and tissues, albeit at much lower levels than found in muscle or liver. However, metabolic and physiological roles of glycogen in other tissues are poorly understood. This series of Minireviews summarizes what is known about the enzymes involved in brain glycogen metabolism and studies that have linked glycogen metabolism to multiple brain functions involving metabolic communication between astrocytes and neurons. Recent studies unexpectedly linking some forms of epilepsy to mutations in two poorly understood proteins involved in glycogen metabolism are also reviewed.
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Affiliation(s)
- Gerald M Carlson
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160.
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72201.
| | - Roger J Colbran
- Department of Molecular Physiology & Biophysics, The Vanderbilt Brain Institute, and The Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615.
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12
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Abstract
The key regulatory enzymes of glycogenolysis are phosphorylase kinase, a hetero-oligomer with four different types of subunits, and glycogen phosphorylase, a homodimer. Both enzymes are activated by phosphorylation and small ligands, and both enzymes have distinct isoforms that are predominantly expressed in muscle, liver, or brain; however, whole-transcriptome high-throughput sequencing analyses show that in brain both of these enzymes are likely composed of subunit isoforms representing all three tissues. This Minireview examines the regulatory properties of the isoforms of these two enzymes expressed in the three tissues, focusing on their potential regulatory similarities and differences. Additionally, the activity, structure, and regulation of the remaining enzyme necessary for glycogenolysis, glycogen-debranching enzyme, are also reviewed.
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Affiliation(s)
- Owen W Nadeau
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421
| | - Joseph D Fontes
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421
| | - Gerald M Carlson
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421.
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13
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Buneeva O, Gnedenko O, Zgoda V, Kopylov A, Glover V, Ivanov A, Medvedev A, Archakov A. Isatin-binding proteins of rat and mouse brain: Proteomic identification and optical biosensor validation. Proteomics 2009; 10:23-37. [DOI: 10.1002/pmic.200900492] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Immunohistochemical Localization of Glycogen Phosphorylase Isozymes in the Rat Gastrointestinal Muscle Layers and Enteric Nervous System. Neurochem Res 2008; 34:876-83. [DOI: 10.1007/s11064-008-9834-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 08/07/2008] [Indexed: 10/21/2022]
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15
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Schmid H, Pfeiffer-Guglielmi B, Dolderer B, Thiess U, Verleysdonk S, Hamprecht B. Expression of the Brain and Muscle Isoforms of Glycogen Phosphorylase in Rat Heart. Neurochem Res 2008; 34:581-6. [DOI: 10.1007/s11064-008-9825-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 08/05/2008] [Indexed: 10/21/2022]
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Schmid H, Dolderer B, Thiess U, Verleysdonk S, Hamprecht B. Renal expression of the brain and muscle isoforms of glycogen phosphorylase in different cell types. Neurochem Res 2008; 33:2575-82. [PMID: 18338248 DOI: 10.1007/s11064-008-9640-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 02/20/2008] [Indexed: 11/30/2022]
Abstract
Kidney contains glycogen. Glycogen is degraded by glycogen phosphorylase (GP). This enzyme comes in three isoforms, one of which, the brain isozyme (GP BB), is known to occur in kidney. Its pattern of distribution in rat kidney was studied in comparison to that of the muscle isoform (GP MM) with the aim to see if for GP BB and GP MM there were functional similarities in brain and kidney. In immunoblotting and quantitative reverse transcriptase polymerase chain reaction (RT-PCR) experiments, both isozymes and their respective mRNAs were found in kidney homogenates. GP BB was immunocytochemically detected in collecting ducts which were identified by the marker protein aquaporin-2. GP MM was localized exclusively in interstitial cells of cortex and outer medulla. These cells were identified as fibroblasts by their expression of 5'-ectonucleotidase (cortex) or by their morphology (outer medulla). The physiological role of both isozymes is discussed in respect to local demands of energy and of proteoglycan building blocks.
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Affiliation(s)
- Heide Schmid
- Interfaculty Institute for Biochemistry, University of Tuebingen, Hoppe-Seyler-Str. 4, 72076, Tuebingen, Germany
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17
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Walls AB, Sickmann HM, Brown A, Bouman SD, Ransom B, Schousboe A, Waagepetersen HS. Characterization of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) as an inhibitor of brain glycogen shunt activity. J Neurochem 2008; 105:1462-70. [PMID: 18221367 DOI: 10.1111/j.1471-4159.2008.05250.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pharmacological properties of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB), a potent inhibitor of glycogen phosphorylase and synthase activity in liver preparations, were characterized in different brain tissue preparations as a prerequisite for using it as a tool to investigate brain glycogen metabolism. Its inhibitory effect on glycogen phosphorylase was studied in homogenates of brain tissue and astrocytes and IC50-values close to 400 nM were found. However, the concentration of DAB needed for inhibition of glycogen shunt activity, i.e. glucose metabolism via glycogen, in intact astrocytes was almost three orders of magnitude higher. Additionally, such complete inhibition required a pre-incubation period, a finding possibly reflecting a limited permeability of the astrocytic membrane. DAB did not affect the accumulation of 2-deoxyglucose-6-phosphate indicating that the transport of DAB is not mediated by the glucose transporter. DAB had no effect on enzymes involving glucose-6-phosphate, i.e. glucose-6-phosphate dehydrogenase, phosphoglucoisomerase and hexokinase. Furthermore, DAB was evaluated in a functional preparation of the isolated mouse optic nerve, in which its presence severely reduced the ability to sustain evoked compound action potentials in the absence of glucose, a condition in which glycogen serves as an important energy substrate. Based on the experimental findings, DAB can be used to evaluate glycogen shunt activity and its functional importance in intact brain tissue and cells at a concentration of 300-1000 muM and a pre-incubation period of 1 h.
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Affiliation(s)
- Anne B Walls
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark
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Pfeiffer-Guglielmi B, Coles JA, Francke M, Reichenbach A, Fleckenstein B, Jung G, Nicaise G, Hamprecht B. Immunocytochemical analysis of rat vagus nerve by antibodies against glycogen phosphorylase isozymes. Brain Res 2006; 1110:23-9. [PMID: 16879805 DOI: 10.1016/j.brainres.2006.06.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2006] [Revised: 06/16/2006] [Accepted: 06/18/2006] [Indexed: 11/30/2022]
Abstract
Glycogen is an endogenous store of glucose equivalents for energy metabolism in many tissues. The brain contains a significant amount of glycogen the role of which as an energy reserve is currently under debate. Apparently little is known concerning a possible role of glycogen in peripheral nerves. We have demonstrated immunocytochemically the presence of glycogen phosphorylase (GP), a key enzyme in glycogen metabolism, in large and small axons of the rat vagus nerve, but not in Schwann cells. Furthermore, the isozyme-specific antibodies applied detected only the presence of the brain isoform BB of GP, but not the muscle isoform MM. This is in agreement with the occurrence of solely the BB isoform in the few brain and spinal cord neurons that contain GP. In contrast, astroglial cells in brain and spinal cord have previously been shown to contain both isoforms. Since GP isozymes are regulated differentially, the expression of isoform BB may provide hints to possible functions of glycogen in the vagus nerve.
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Pfeiffer-Guglielmi B, Francke M, Reichenbach A, Fleckenstein B, Jung G, Hamprecht B. Glycogen phosphorylase isozyme pattern in mammalian retinal Müller (glial) cells and in astrocytes of retina and optic nerve. Glia 2005; 49:84-95. [PMID: 15390095 DOI: 10.1002/glia.20102] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Müller cells, the radially oriented dominant macroglial cells of the retina, are known to contain abundant glycogen as well as the key enzyme for its degradation, glycogen phosphorylase (GP), but the expressed isozyme pattern is unknown. To elucidate the isoform expression pattern, specific antisera directed against the brain (BB) and muscle (MM) isoforms of GP were applied to retinal sections, isolated Müller cells, and sections of the optic nerve. We show that Müller cells of rat, rabbit, guinea pig, and mouse retina exclusively express the BB isoform. Astrocytes of rat and rabbit optic nerve, as well as retina express only the BB isoform. In contrast, astrocytes in the brain and spinal cord as well as the epithelial cells of the pars caeca and of the ciliary body express both the BB and MM isoform. This result may indicate some differences in the role of glycogen in retinal macroglia and brain astrocytes, reflecting a local specialization of macroglia in the retina proper.
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Pfeiffer-Guglielmi B, Fleckenstein B, Jung G, Hamprecht B. Immunocytochemical localization of glycogen phosphorylase isozymes in rat nervous tissues by using isozyme-specific antibodies. J Neurochem 2003; 85:73-81. [PMID: 12641728 DOI: 10.1046/j.1471-4159.2003.01644.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Isozyme-specific antibodies were raised against peptides from the low-homology regions of the sequences of rat glycogen phosphorylase BB and MM isozymes by immunization of rabbits and guinea pigs. Immunocytochemical double-labelling experiments on frozen sections of rat nervous tissues were performed to investigate the isozyme localization pattern. Astrocytes throughout the brain and spinal cord expressed both isozymes in perfect co-localization. Ependymal cells only expressed the BB isozyme. Most neurones were not immunoreactive. The rare neurones that contained glycogen phosphorylase only expressed the BB isozyme. Nearly all of these neurones formed part of the afferent somatosensory system. These findings stress the general importance of glycogen in neural energy metabolism and indicate a special role for the glycogen phosphorylase BB isozyme in neurones in the somatosensory system.
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Affiliation(s)
- Brigitte Pfeiffer-Guglielmi
- Physiologisch-Chemisches Institut der Universität and Institut für Organische Chemie der Universität, Tübingen, Germany
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