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Stefanik E, Dubińska-Magiera M, Lewandowski D, Daczewska M, Migocka-Patrzałek M. Metabolic aspects of glycogenolysis with special attention to McArdle disease. Mol Genet Metab 2024; 142:108532. [PMID: 39018613 DOI: 10.1016/j.ymgme.2024.108532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 07/03/2024] [Accepted: 07/03/2024] [Indexed: 07/19/2024]
Abstract
The physiological function of muscle glycogen is to meet the energy demands of muscle contraction. The breakdown of glycogen occurs through two distinct pathways, primarily cytosolic and partially lysosomal. To obtain the necessary energy for their function, skeletal muscles utilise also fatty acids in the β-oxidation. Ketogenesis is an alternative metabolic pathway for fatty acids, which provides an energy source during fasting and starvation. Diseases arising from impaired glycogenolysis lead to muscle weakness and dysfunction. Here, we focused on the lack of muscle glycogen phosphorylase (PYGM), a rate-limiting enzyme for glycogenolysis in skeletal muscles, which leads to McArdle disease. Metabolic myopathies represent a group of genetic disorders characterised by the limited ability of skeletal muscles to generate energy. Here, we discuss the metabolic aspects of glycogenosis with a focus on McArdle disease, offering insights into its pathophysiology. Glycogen accumulation may influence the muscle metabolic dynamics in different ways. We emphasize that a proper treatment approach for such diseases requires addressing three important and interrelated aspects, which include: symptom relief therapy, elimination of the cause of the disease (lack of a functional enzyme) and effective and early diagnosis.
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Affiliation(s)
- Ewa Stefanik
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, 50-335 Wrocław, Poland..
| | - Magda Dubińska-Magiera
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, 50-335 Wrocław, Poland..
| | - Damian Lewandowski
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, 50-335 Wrocław, Poland..
| | - Małgorzata Daczewska
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, 50-335 Wrocław, Poland..
| | - Marta Migocka-Patrzałek
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, 50-335 Wrocław, Poland..
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2
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A Proteomic Platform Unveils the Brain Glycogen Phosphorylase as a Potential Therapeutic Target for Glioblastoma Multiforme. Int J Mol Sci 2022; 23:ijms23158200. [PMID: 35897773 PMCID: PMC9331883 DOI: 10.3390/ijms23158200] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 11/22/2022] Open
Abstract
In the last few years, several efforts have been made to identify original strategies against glioblastoma multiforme (GBM): this requires a more detailed investigation of the molecular mechanism of GBM so that novel targets can be identified for new possible therapeutic agents. Here, using a combined biochemical and proteomic approach, we evaluated the ability of a blood–brain barrier-permeable 2,3-benzodiazepin-4-one, called 1g, to interfere with the activity and the expression of brain glycogen phosphorylase (PYGB) on U87MG cell line in parallel with the capability of this compound to inhibit the cell growth and cycle. Thus, our results highlighted PYGB as a potential therapeutic target in GBM prompting 1g as a capable anticancer drug thanks to its ability to negatively modulate the uptake and metabolism of glucose, the so-called “Warburg effect”, whose increase is considered a common feature of cancer cells in respect of their normal counterparts.
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3
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Zois CE, Hendriks AM, Haider S, Pires E, Bridges E, Kalamida D, Voukantsis D, Lagerholm BC, Fehrmann RSN, den Dunnen WFA, Tarasov AI, Baba O, Morris J, Buffa FM, McCullagh JSO, Jalving M, Harris AL. Liver glycogen phosphorylase is upregulated in glioblastoma and provides a metabolic vulnerability to high dose radiation. Cell Death Dis 2022; 13:573. [PMID: 35764612 PMCID: PMC9240045 DOI: 10.1038/s41419-022-05005-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 05/16/2022] [Accepted: 06/08/2022] [Indexed: 01/21/2023]
Abstract
Channelling of glucose via glycogen, known as the glycogen shunt, may play an important role in the metabolism of brain tumours, especially in hypoxic conditions. We aimed to dissect the role of glycogen degradation in glioblastoma (GBM) response to ionising radiation (IR). Knockdown of the glycogen phosphorylase liver isoform (PYGL), but not the brain isoform (PYGB), decreased clonogenic growth and survival of GBM cell lines and sensitised them to IR doses of 10-12 Gy. Two to five days after IR exposure of PYGL knockdown GBM cells, mitotic catastrophy and a giant multinucleated cell morphology with senescence-like phenotype developed. The basal levels of the lysosomal enzyme alpha-acid glucosidase (GAA), essential for autolysosomal glycogen degradation, and the lipidated forms of gamma-aminobutyric acid receptor-associated protein-like (GABARAPL1 and GABARAPL2) increased in shPYGL U87MG cells, suggesting a compensatory mechanism of glycogen degradation. In response to IR, dysregulation of autophagy was shown by accumulation of the p62 and the lipidated form of GABARAPL1 and GABARAPL2 in shPYGL U87MG cells. IR increased the mitochondrial mass and the colocalisation of mitochondria with lysosomes in shPYGL cells, thereby indicating reduced mitophagy. These changes coincided with increased phosphorylation of AMP-activated protein kinase and acetyl-CoA carboxylase 2, slower ATP generation in response to glucose loading and progressive loss of oxidative phosphorylation. The resulting metabolic deficiencies affected the availability of ATP required for mitosis, resulting in the mitotic catastrophy observed in shPYGL cells following IR. PYGL mRNA and protein levels were higher in human GBM than in normal human brain tissues and high PYGL mRNA expression in GBM correlated with poor patient survival. In conclusion, we show a major new role for glycogen metabolism in GBM cancer. Inhibition of glycogen degradation sensitises GBM cells to high-dose IR indicating that PYGL is a potential novel target for the treatment of GBMs.
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Affiliation(s)
- Christos E Zois
- Molecular Oncology Laboratories, Department of Oncology, Oxford University, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK.
| | - Anne M Hendriks
- Molecular Oncology Laboratories, Department of Oncology, Oxford University, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
- Department of Medical Oncology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands
| | - Syed Haider
- The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, UK
| | | | - Esther Bridges
- Molecular Oncology Laboratories, Department of Oncology, Oxford University, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
| | - Dimitra Kalamida
- Department of Oncology, Democritus University of Thrace, Alexandroupolis, Greece
| | - Dimitrios Voukantsis
- The Bioinformatics Hub, Department of Oncology, University of Oxford, Oxford, UK
| | | | - Rudolf S N Fehrmann
- Department of Medical Oncology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands
| | - Wilfred F A den Dunnen
- Department of Pathology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands
| | - Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Otto Baba
- Tokushima University Graduate School, Tokushima, Japan
| | - John Morris
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Francesca M Buffa
- Department of Oncology, University of Oxford, Churchill Hospital, Oxford, UK
| | | | - Mathilde Jalving
- Department of Medical Oncology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands
| | - Adrian L Harris
- Molecular Oncology Laboratories, Department of Oncology, Oxford University, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK.
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4
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Migocka-Patrzałek M, Elias M. Muscle Glycogen Phosphorylase and Its Functional Partners in Health and Disease. Cells 2021; 10:cells10040883. [PMID: 33924466 PMCID: PMC8070155 DOI: 10.3390/cells10040883] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/09/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023] Open
Abstract
Glycogen phosphorylase (PG) is a key enzyme taking part in the first step of glycogenolysis. Muscle glycogen phosphorylase (PYGM) differs from other PG isoforms in expression pattern and biochemical properties. The main role of PYGM is providing sufficient energy for muscle contraction. However, it is expressed in tissues other than muscle, such as the brain, lymphoid tissues, and blood. PYGM is important not only in glycogen metabolism, but also in such diverse processes as the insulin and glucagon signaling pathway, insulin resistance, necroptosis, immune response, and phototransduction. PYGM is implicated in several pathological states, such as muscle glycogen phosphorylase deficiency (McArdle disease), schizophrenia, and cancer. Here we attempt to analyze the available data regarding the protein partners of PYGM to shed light on its possible interactions and functions. We also underline the potential for zebrafish to become a convenient and applicable model to study PYGM functions, especially because of its unique features that can complement data obtained from other approaches.
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Matsui T. Exhaustive endurance exercise activates brain glycogen breakdown and lactate production more than insulin-induced hypoglycemia. Am J Physiol Regul Integr Comp Physiol 2021; 320:R500-R507. [PMID: 33533310 DOI: 10.1152/ajpregu.00119.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 01/29/2021] [Indexed: 11/22/2022]
Abstract
Brain glycogen localized in astrocytes produces lactate via cAMP signaling, which regulates memory functions and endurance capacity. Exhaustive endurance exercise with hypoglycemia decreases brain glycogen, although the mechanism underlying this phenomenon remains unclear. Since insulin-induced hypoglycemia decreases brain glycogen, this study tested the hypothesis that hypoglycemia mediates exercise-induced brain glycogen decrease. To test the hypothesis, the effects of insulin- and exhaustive exercise-induced hypoglycemia on brain glycogen levels were compared using the microwave irradiation method in adult Wistar rats. The insulin challenge and exhaustive exercise induced similar levels of severe hypoglycemia. Glycogen in the hypothalamus and cerebellum decreased similarly with the insulin challenge and exhaustive exercise; however, glycogen in the cortex, hippocampus, and brainstem of the exercise group were lower compared with the insulin group. Brain lactate and cAMP levels in the hypothalamus and cerebellum increased similarly with the insulin challenge and exhaustive exercise, but those in the cortex, hippocampus, and brainstem of the exercise group were higher compared with the insulin group. Blood glucose correlated positively with brain glycogen, but the slope of regression lines was greater in the exercise group compared with the insulin group in the cortex, hippocampus, and brainstem, but not the hypothalamus and cerebellum. These findings support the hypothesis that hypoglycemia mediates the exercise-induced reduction in brain glycogen, at least in the hypothalamus and cerebellum. However, glycogen reduction during exhaustive endurance exercise in the cortex, hippocampus, and brainstem is not due to hypoglycemia alone, implicating the role of exercise-specific neuronal activity in brain glycogen decrease.
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Affiliation(s)
- Takashi Matsui
- Exercise Biochemistry Division, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
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Pfeiffer-Guglielmi B, Jansen RP. The Motor Neuron-Like Cell Line NSC-34 and Its Parent Cell Line N18TG2 Have Glycogen that is Degraded Under Cellular Stress. Neurochem Res 2021; 46:1567-1576. [PMID: 33786720 PMCID: PMC8084819 DOI: 10.1007/s11064-021-03297-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/07/2021] [Accepted: 03/08/2021] [Indexed: 11/24/2022]
Abstract
Brain glycogen has a long and versatile history: Primarily regarded as an evolutionary remnant, it was then thought of as an unspecific emergency fuel store. A dynamic role for glycogen in normal brain function has been proposed later but exclusively attributed to astrocytes, its main storage site. Neuronal glycogen had long been neglected, but came into focus when sensitive technical methods allowed quantification of glycogen at low concentration range and the detection of glycogen metabolizing enzymes in cells and cell lysates. Recently, an active role of neuronal glycogen and even its contribution to neuronal survival could be demonstrated. We used the neuronal cell lines NSC-34 and N18TG2 and could demonstrate that they express the key-enzymes of glycogen metabolism, glycogen phosphorylase and glycogen synthase and contain glycogen which is mobilized on glucose deprivation and elevated potassium concentrations, but not by hormones stimulating cAMP formation. Conditions of metabolic stress, namely hypoxia, oxidative stress and pH lowering, induce glycogen degradation. Our studies revealed that glycogen can contribute to the energy supply of neuronal cell lines in situations of metabolic stress. These findings shed new light on the so far neglected role of neuronal glycogen. The key-enzyme in glycogen degradation is glycogen phosphorylase. Neurons express only the brain isoform of the enzyme that is supposed to be activated primarily by the allosteric activator AMP and less by covalent phosphorylation via the cAMP cascade. Our results indicate that neuronal glycogen is not degraded upon hormone action but by factors lowering the energy charge of the cells directly.
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Affiliation(s)
- Brigitte Pfeiffer-Guglielmi
- Interfaculty Institute for Biochemistry, University of Tübingen, Auf der Morgenstelle 34, 72076, Tübingen, Germany.
| | - Ralf-Peter Jansen
- Interfaculty Institute for Biochemistry, University of Tübingen, Auf der Morgenstelle 34, 72076, Tübingen, Germany
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7
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Microscopic and mechanical properties of undistributed and remoulded red clay from Guiyang, China. Sci Rep 2020; 10:18003. [PMID: 33093454 PMCID: PMC7583258 DOI: 10.1038/s41598-020-71605-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 08/05/2020] [Indexed: 11/29/2022] Open
Abstract
Unconsolidated-undrained (UU) tests were conducted to investigate the mechanical and morphological properties of undisturbed and remoulded red clay, with the microscopic characteristics determined by scanning electron microscopy (SEM). The microanalysis showed that the red clay aggregate was granular, curved-slice and thin layered and flower-shaped ellipsoid, with X and Y-type cracks and pores in the undisturbed red clay. Moreover, the contact modes of red clay aggregates were point contact, line contact, surface contact and mosaic contact. In addition, the main microstructure red clay was flocculation, honeycomb and pseudosphere structures. The pores in undisturbed soil were arranged in one direction, with no obvious directionality in remoulded red clay. The pore area, perimeter and maximum length of undisturbed red clay were smaller than those of remoulded red clay, with a larger probability entropy, probability distribution index and fractal dimension of pore distribution of undisturbed red clay than remoulded red clay. UU tests showed that the shear strength of undisturbed red clay was higher than that of remoulded red clay.
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8
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Bai Y, Li X, Zhang D, Hou C, Zheng X, Chen L, Ren C. Effects of different ATP contents on phosphorylation level of glycogen phosphorylase and its activity in lamb during incubation at 4 ℃
in vitro. Int J Food Sci Technol 2020. [DOI: 10.1111/ijfs.14565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Yuqiang Bai
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Xin Li
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Dequan Zhang
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Chengli Hou
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Xiaochun Zheng
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Li Chen
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
| | - Chi Ren
- Key Laboratory of Agro‐Products Processing Ministry of Agriculture and Rural Affairs Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Beijing 100193 China
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9
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Bai Y, Li X, Zhang D, Chen L, Hou C, Zheng X, Ren C. Effects of phosphorylation on the activity of glycogen phosphorylase in mutton during incubation at 4 °C in vitro. Food Chem 2020; 313:126162. [PMID: 31951884 DOI: 10.1016/j.foodchem.2020.126162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/28/2019] [Accepted: 01/02/2020] [Indexed: 11/15/2022]
Abstract
The aim of this study was to assess the effects of the phosphorylation levels of glycogen phosphorylase on its activity in mutton sarcoplasmic protein samples during incubation at 4 °C. Samples of sarcoplasmic proteins from mutton longissimus thoracis muscles were prepared and separated into three treatment groups to obtain glycogen phosphorylase with different phosphorylation levels, which were (1) treated with protein kinase A, (2) treated with alkaline phosphatase, and (3) left untreated (control). Glycogen phosphorylase phosphorylation levels and activity as well as the levels of related endogenous substances were assessed. The results showed that phosphorylation of glycogen phosphorylase in mutton promoted its activity during incubation at 4 °C. The activity of glycogen phosphorylase was also influenced by other factors (glycogen, glucose, glucose 6-phosphate, ATP, etc.) in vitro. The combined effects of phosphorylation and endogenous substances on glycogen phosphorylase activity varied at different incubation times.
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Affiliation(s)
- Yuqiang Bai
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Xin Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
| | - Dequan Zhang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
| | - Li Chen
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Chengli Hou
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Xiaochun Zheng
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Chi Ren
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
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10
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Scalco RS, Stemmerik M, Løkken N, Vissing CR, Madsen KL, Michalak Z, Pattni J, Godfrey R, Samandouras G, Bassett P, Holton JL, Krag T, Haller RG, Sewry C, Wigley R, Vissing J, Quinlivan R. Results of an open label feasibility study of sodium valproate in people with McArdle disease. Neuromuscul Disord 2020; 30:734-741. [PMID: 32811700 DOI: 10.1016/j.nmd.2020.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 04/21/2020] [Accepted: 04/28/2020] [Indexed: 12/13/2022]
Abstract
McArdle disease results from a lack of muscle glycogen phosphorylase in skeletal muscle tissue. Regenerating skeletal muscle fibres can express the brain glycogen phosphorylase isoenzyme. Stimulating expression of this enzyme could be a therapeutic strategy. Animal model studies indicate that sodium valproate (VPA) can increase expression of phosphorylase in skeletal muscle affected with McArdle disease. This study was designed to assess whether VPA can modify expression of brain phosphorylase isoenzyme in people with McArdle disease. This phase II, open label, feasibility pilot study to assess efficacy of six months treatment with VPA (20 mg/kg/day) included 16 people with McArdle disease. Primary outcome assessed changes in VO2peak during an incremental cycle test. Secondary outcomes included: phosphorylase enzyme expression in post-treatment muscle biopsy, total distance walked in 12 min, plasma lactate change (forearm exercise test) and quality of life (SF36). Safety parameters. 14 participants completed the trial, VPA treatment was well tolerated; weight gain was the most frequently reported drug-related adverse event. There was no clinically meaningful change in any of the primary or secondary outcome measures including: VO2peak, 12 min walk test and muscle biopsy to look for a change in the number of phosphorylase positive fibres between baseline and 6 months of treatment. Although this was a small open label feasibility study, it suggests that a larger randomised controlled study of VPA, may not be worthwhile.
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Affiliation(s)
- Renata S Scalco
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom; CAPES Foundation, Ministry of Education, Brazil
| | - Mads Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Nicoline Løkken
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Christoffer R Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Karen L Madsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Zuzanna Michalak
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom
| | - Jatin Pattni
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom
| | - Richard Godfrey
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom; Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, United Kingdom
| | - George Samandouras
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom
| | | | - Janice L Holton
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom
| | - Thomas Krag
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Ronald G Haller
- Department of Neurology, The University of Texas Southwestern Medical Center and Neuromuscular Centre, Institute for exercise and environmental medicine, Dallas, Texas, 75231, USA
| | - C Sewry
- RJAH Orthopaedic Hospital NHS Foundation Trust Oswestry, United Kingdom
| | - Ralph Wigley
- Great Ormond Street Hospital, London, United Kingdom
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark
| | - Ros Quinlivan
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, United Kingdom.
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11
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Metabolic responses in Antarctic Nototheniidae brains subjected to thermal stress. Brain Res 2019; 1708:126-137. [PMID: 30527682 DOI: 10.1016/j.brainres.2018.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 11/08/2018] [Accepted: 12/04/2018] [Indexed: 12/23/2022]
Abstract
Antarctic Nototheniidae is an attractive group for studying metabolic and physiological responses at high temperatures. The present work investigated the metabolic responses of the carbohydrate metabolism and antioxidant system to thermal stress at 8 °C (for 2-144 h) in the brains of Notothenia rossii and Notothenia coriiceps. In N. coriiceps, glycogenolysis was essential in the first hours of exposure (2 h) at 8 °C and, in addition to inhibiting glucose-6-phosphatase activity, was important for activating the pentose phosphate pathway. In N. rossii, anaerobic metabolism was reduced in the first hours of exposure (2 and 6 h) at 8 °C, followed by reduced hexokinase activity, suggesting energy regulation between neurons and astrocytes. The antioxidant system results indicated the importance of the actions of the glutathione-dependent antioxidant enzymes glutathione-S-transferase and glutathione peroxidase as well as those of catalase in N. coriiceps and the action of glutathione-S-transferase, glutathione peroxidase and glutathione reductase in N. rossii, especially during the first 12 h of thermal stress exposure. These results indicate tissue-specific patterns and species-specific responses to this stress.
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12
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Wu L, Wong CP, Swanson RA. Methodological considerations for studies of brain glycogen. J Neurosci Res 2019; 97:914-922. [PMID: 30892752 DOI: 10.1002/jnr.24412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 01/02/2023]
Abstract
Glycogen stores in the brain have been recognized for decades, but the underlying physiological function of this energy reserve remains elusive. This uncertainty stems in part from several technical challenges inherent in the study of brain glycogen metabolism. These include low glycogen content in the brain, non-homogeneous labeling of glycogen by radiotracers, rapid glycogenolysis during postmortem tissue handling, and effects of the stress response on brain glycogen turnover. Here we briefly review the aspects of the glycogen structure and metabolism that bear on these technical challenges and present ways they can be addressed.
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Affiliation(s)
- Long Wu
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Health Care System, San Francisco, California
| | - Candance P Wong
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Health Care System, San Francisco, California
| | - Raymond A Swanson
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Health Care System, San Francisco, California
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13
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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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14
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The Structure and the Regulation of Glycogen Phosphorylases in Brain. ADVANCES IN NEUROBIOLOGY 2019; 23:125-145. [DOI: 10.1007/978-3-030-27480-1_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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15
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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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16
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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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17
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Mathieu C, Duval R, Cocaign A, Petit E, Bui LC, Haddad I, Vinh J, Etchebest C, Dupret JM, Rodrigues-Lima F. An Isozyme-specific Redox Switch in Human Brain Glycogen Phosphorylase Modulates Its Allosteric Activation by AMP. J Biol Chem 2016; 291:23842-23853. [PMID: 27660393 DOI: 10.1074/jbc.m116.757062] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 09/21/2016] [Indexed: 12/22/2022] Open
Abstract
Brain glycogen and its metabolism are increasingly recognized as major players in brain functions. Moreover, alteration of glycogen metabolism in the brain contributes to neurodegenerative processes. In the brain, both muscle and brain glycogen phosphorylase isozymes regulate glycogen mobilization. However, given their distinct regulatory features, these two isozymes could confer distinct metabolic functions of glycogen in brain. Interestingly, recent proteomics studies have identified isozyme-specific reactive cysteine residues in brain glycogen phosphorylase (bGP). In this study, we show that the activity of human bGP is redox-regulated through the formation of a disulfide bond involving a highly reactive cysteine unique to the bGP isozyme. We found that this disulfide bond acts as a redox switch that precludes the allosteric activation of the enzyme by AMP without affecting its activation by phosphorylation. This unique regulatory feature of bGP sheds new light on the isoform-specific regulation of glycogen phosphorylase and glycogen metabolism.
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Affiliation(s)
- Cécile Mathieu
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris
| | - Romain Duval
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris
| | - Angélique Cocaign
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris
| | - Emile Petit
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris
| | - Linh-Chi Bui
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris
| | - Iman Haddad
- ESPCI Paris, PSL Research University, Spectrométrie de Masse Biologique et Protéomique (SMPB), CNRS USR 3149, 10 rue Vauquelin, F75231 Paris cedex 05, France
| | - Joelle Vinh
- ESPCI Paris, PSL Research University, Spectrométrie de Masse Biologique et Protéomique (SMPB), CNRS USR 3149, 10 rue Vauquelin, F75231 Paris cedex 05, France
| | - Catherine Etchebest
- INSERM, UMR S1134, Université Paris Diderot, F-75015 Paris.,Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris.,Institut National de la Transfusion Sanguine (INTS), 75015 Paris.,GR-Ex, Laboratoire d'excellence, 75015 Paris, and.,UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France
| | - Jean-Marie Dupret
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris.,UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France
| | - Fernando Rodrigues-Lima
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, .,UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France
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18
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Mathieu C, Li de la Sierra-Gallay I, Duval R, Xu X, Cocaign A, Léger T, Woffendin G, Camadro JM, Etchebest C, Haouz A, Dupret JM, Rodrigues-Lima F. Insights into Brain Glycogen Metabolism: THE STRUCTURE OF HUMAN BRAIN GLYCOGEN PHOSPHORYLASE. J Biol Chem 2016; 291:18072-83. [PMID: 27402852 DOI: 10.1074/jbc.m116.738898] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Indexed: 11/06/2022] Open
Abstract
Brain glycogen metabolism plays a critical role in major brain functions such as learning or memory consolidation. However, alteration of glycogen metabolism and glycogen accumulation in the brain contributes to neurodegeneration as observed in Lafora disease. Glycogen phosphorylase (GP), a key enzyme in glycogen metabolism, catalyzes the rate-limiting step of glycogen mobilization. Moreover, the allosteric regulation of the three GP isozymes (muscle, liver, and brain) by metabolites and phosphorylation, in response to hormonal signaling, fine-tunes glycogenolysis to fulfill energetic and metabolic requirements. Whereas the structures of muscle and liver GPs have been known for decades, the structure of brain GP (bGP) has remained elusive despite its critical role in brain glycogen metabolism. Here, we report the crystal structure of human bGP in complex with PEG 400 (2.5 Å) and in complex with its allosteric activator AMP (3.4 Å). These structures demonstrate that bGP has a closer structural relationship with muscle GP, which is also activated by AMP, contrary to liver GP, which is not. Importantly, despite the structural similarities between human bGP and the two other mammalian isozymes, the bGP structures reveal molecular features unique to the brain isozyme that provide a deeper understanding of the differences in the activation properties of these allosteric enzymes by the allosteric effector AMP. Overall, our study further supports that the distinct structural and regulatory properties of GP isozymes contribute to the different functions of muscle, liver, and brain glycogen.
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Affiliation(s)
- Cécile Mathieu
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Ines Li de la Sierra-Gallay
- the Fonction et Architecture des Assemblages Macromoléculaires, Institut de Biologie Intégrative de la Cellule, Université Paris Sud, UMR 9198 Orsay, 91405 France
| | - Romain Duval
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Ximing Xu
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Angélique Cocaign
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Thibaut Léger
- the Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, CNRS UMR 7592, 75013 Paris, France
| | - Gary Woffendin
- Thermo Fisher Scientific, Hemel Hempstead HP2 7GE, United Kingdom
| | - Jean-Michel Camadro
- the Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, CNRS UMR 7592, 75013 Paris, France
| | - Catherine Etchebest
- INSERM, UMR S1134, Université Paris Diderot, 75015 Paris, France, Université Paris Diderot, Sorbonne Paris Cité, 75004 Paris, France, Institut National de la Transfusion Sanguine, 75015 Paris, France, Laboratoire d'Excellence GR-Ex, 75015 Paris, France, UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France, and
| | - Ahmed Haouz
- the Institut Pasteur, Plateforme de Cristallographie, CNRS UMR 3528, 75015 Paris, France
| | - Jean-Marie Dupret
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France, UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France, and
| | - Fernando Rodrigues-Lima
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France, UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France, and
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19
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Duran J, Guinovart JJ. Brain glycogen in health and disease. Mol Aspects Med 2015; 46:70-7. [PMID: 26344371 DOI: 10.1016/j.mam.2015.08.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 08/21/2015] [Indexed: 12/18/2022]
Abstract
Glycogen is present in the brain at much lower concentrations than in muscle or liver. However, by characterizing an animal depleted of brain glycogen, we have shown that the polysaccharide plays a key role in learning capacity and in activity-dependent changes in hippocampal synapse strength. Since glycogen is essentially found in astrocytes, the diverse roles proposed for this polysaccharide in the brain have been attributed exclusively to these cells. However, we have demonstrated that neurons have an active glycogen metabolism that contributes to tolerance to hypoxia. However, these cells can store only minute amounts of glycogen, since the progressive accumulation of this molecule leads to neuronal loss. Loss-of-function mutations in laforin and malin cause Lafora disease. This condition is characterized by the presence of high numbers of insoluble polyglucosan bodies, known as Lafora bodies, in neuronal cells. Our findings reveal that the accumulation of this aberrant glycogen accounts for the neurodegeneration and functional consequences, as well as the impaired autophagy, observed in models of this disease. Similarly glycogen synthase is responsible for the accumulation of corpora amylacea, which are polysaccharide-based aggregates present in the neurons of aged human brains. Our findings change the current view of the role of glycogen in the brain and reveal that endogenous neuronal glycogen metabolism is important under stress conditions and that neuronal glycogen accumulation contributes to neurodegenerative diseases and to aging-related corpora amylacea formation.
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Affiliation(s)
- Jordi Duran
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain
| | - Joan J Guinovart
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain; Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain.
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20
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Muhič M, Vardjan N, Chowdhury HH, Zorec R, Kreft M. Insulin and Insulin-like Growth Factor 1 (IGF-1) Modulate Cytoplasmic Glucose and Glycogen Levels but Not Glucose Transport across the Membrane in Astrocytes. J Biol Chem 2015; 290:11167-76. [PMID: 25792745 DOI: 10.1074/jbc.m114.629063] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 01/21/2023] Open
Abstract
Astrocytes contain glycogen, an energy buffer, which can bridge local short term energy requirements in the brain. Glycogen levels reflect a dynamic equilibrium between glycogen synthesis and glycogenolysis. Many factors that include hormones and neuropeptides, such as insulin and insulin-like growth factor 1 (IGF-1) likely modulate glycogen stores in astrocytes, but detailed mechanisms at the cellular level are sparse. We used a glucose nanosensor based on Förster resonance energy transfer to monitor cytosolic glucose concentration with high temporal resolution and a cytochemical approach to determine glycogen stores in single cells. The results show that after glucose depletion, glycogen stores are replenished. Insulin and IGF-1 boost the process of glycogen formation. Although astrocytes appear to express glucose transporter GLUT4, glucose entry across the astrocyte plasma membrane is not affected by insulin. Stimulation of cells with insulin and IGF-1 decreased cytosolic glucose concentration, likely because of elevated glucose utilization for glycogen synthesis.
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Affiliation(s)
- Marko Muhič
- From the Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
| | - Nina Vardjan
- From the Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia, Celica Biomedical, 1000 Ljubljana, Slovenia, and
| | - Helena H Chowdhury
- From the Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia, Celica Biomedical, 1000 Ljubljana, Slovenia, and
| | - Robert Zorec
- From the Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia, Celica Biomedical, 1000 Ljubljana, Slovenia, and
| | - Marko Kreft
- From the Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia, Celica Biomedical, 1000 Ljubljana, Slovenia, and the Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
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21
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Holmes AP, Turner PJ, Carter P, Leadbeater W, Ray CJ, Hauton D, Buckler KJ, Kumar P. Glycogen metabolism protects against metabolic insult to preserve carotid body function during glucose deprivation. J Physiol 2014; 592:4493-506. [PMID: 25063821 PMCID: PMC4287740 DOI: 10.1113/jphysiol.2014.276105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/07/2014] [Indexed: 01/08/2023] Open
Abstract
The view that the carotid body (CB) type I cells are direct physiological sensors of hypoglycaemia is challenged by the finding that the basal sensory neuronal outflow from the whole organ is unchanged in response to low glucose. The reason for this difference in viewpoint and how the whole CB maintains its metabolic integrity when exposed to low glucose is unknown. Here we show that, in the intact superfused rat CB, basal sensory neuronal activity was sustained during glucose deprivation for 29.1 ± 1.2 min, before irreversible failure following a brief period of excitation. Graded increases in the basal discharge induced by reducing the superfusate PO2 led to proportional decreases in the time to the pre-failure excitation during glucose deprivation which was dependent on a complete run-down in glycolysis and a fall in cellular energy status. A similar ability to withstand prolonged glucose deprivation was observed in isolated type I cells. Electron micrographs and immunofluorescence staining of rat CB sections revealed the presence of glycogen granules and the glycogen conversion enzymes glycogen synthase I and glycogen phosphorylase BB, dispersed throughout the type I cell cytoplasm. Furthermore, pharmacological attenuation of glycogenolysis and functional depletion of glycogen both significantly reduced the time to glycolytic run-down by ∼33 and 65%, respectively. These findings suggest that type I cell glycogen metabolism allows for the continuation of glycolysis and the maintenance of CB sensory neuronal output in periods of restricted glucose delivery and this may act as a key protective mechanism for the organ during hypoglycaemia. The ability, or otherwise, to preserve energetic status may thus account for variation in the reported capacity of the CB to sense physiological glucose concentrations and may even underlie its function during pathological states associated with augmented CB discharge.
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Affiliation(s)
- Andrew P Holmes
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Philip J Turner
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Paul Carter
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Wendy Leadbeater
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Clare J Ray
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - David Hauton
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Keith J Buckler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Prem Kumar
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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22
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Mamczur P, Borsuk B, Paszko J, Sas Z, Mozrzymas J, Wiśniewski JR, Gizak A, Rakus D. Astrocyte-neuron crosstalk regulates the expression and subcellular localization of carbohydrate metabolism enzymes. Glia 2014; 63:328-40. [DOI: 10.1002/glia.22753] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 09/08/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Piotr Mamczur
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
| | - Borys Borsuk
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
| | - Jadwiga Paszko
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
| | - Zuzanna Sas
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
| | - Jerzy Mozrzymas
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
- Laboratory of Neuroscience; Department of Biophysics; Wrocław Medical University, Chałubińskiego; 3, 50-368 Wrocław Poland
| | - Jacek R. Wiśniewski
- Department of Proteomics and Signal Transduction; Max-Planck-Institute of Biochemistry; Am Klopferspitz 18 D-82152 Martinsried Germany
| | - Agnieszka Gizak
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
| | - Dariusz Rakus
- Department of Animal Molecular Physiology; Institute of Experimental Biology; Wrocław University; Cybulskiego 30, 50-205 Wrocław Poland
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23
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Müller MS, Pedersen SE, Walls AB, Waagepetersen HS, Bak LK. Isoform-selective regulation of glycogen phosphorylase by energy deprivation and phosphorylation in astrocytes. Glia 2014; 63:154-62. [PMID: 25130497 DOI: 10.1002/glia.22741] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 07/29/2014] [Indexed: 11/07/2022]
Abstract
Glycogen phosphorylase (GP) is activated to degrade glycogen in response to different stimuli, to support both the astrocyte's own metabolic demand and the metabolic needs of neurons. The regulatory mechanism allowing such a glycogenolytic response to distinct triggers remains incompletely understood. In the present study, we used siRNA-mediated differential knockdown of the two isoforms of GP expressed in astrocytes, muscle isoform (GPMM), and brain isoform (GPBB), to analyze isoform-specific regulatory characteristics in a cellular setting. Subsequently, we tested the response of each isoform to phosphorylation, triggered by incubation with norepinephrine (NE), and to AMP, increased by glucose deprivation in cells in which expression of one GP isoform had been silenced. Successful knockdown was demonstrated on the protein level by Western blot, and on a functional level by determination of glycogen content showing an increase in glycogen levels following knockdown of either GPMM or GPBB. NE triggered glycogenolysis within 15 min in control cells and after GPBB knockdown. However, astrocytes in which expression of GPMM had been silenced showed a delay in response to NE, with glycogen levels significantly reduced only after 60 min. In contrast, allosteric activation of GP by AMP, induced by glucose deprivation, seemed to mainly affect GPBB, as only knockdown of GPBB, but not of GPMM, delayed the glycogenolytic response to glucose deprivation. Our results indicate that the two GP isoforms expressed in astrocytes respond to different physiological triggers, therefore conferring distinct metabolic functions of brain glycogen.
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Affiliation(s)
- Margit S Müller
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2100, Denmark
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24
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Hernández C, Garcia-Ramírez M, García-Rocha M, Saez-López C, Valverde ÁM, Guinovart JJ, Simó R. Glycogen storage in the human retinal pigment epithelium: a comparative study of diabetic and non-diabetic donors. Acta Diabetol 2014; 51:543-52. [PMID: 24458975 DOI: 10.1007/s00592-013-0549-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/18/2013] [Indexed: 01/18/2023]
Abstract
Liver and muscle glycogen content is reduced in diabetic patients but there is no information on the effect of diabetes on the glycogen content in the retinal pigment epithelium (RPE). The main aim of the study was to compare the glycogen content in the RPE between diabetic and non-diabetic human donors. Glycogen synthase (GS) and glycogen phosphorylase (GP), the key enzymes of glycogen metabolism, as well as their isoforms, were also assessed. For this purpose, 44 human postmortem eye cups were included (22 from 11 type 2 diabetic and 22 from 11 non-diabetic donors matched by age). Human RPE cells cultured in normoglycemic and hyperglycemic conditions were also analyzed. Glycogen content as well as the mRNA, protein content and enzyme activity of GS and GP were determined. In addition, GS and GP isoforms were characterized. In the RPE from diabetic donors, as well as in RPE cells grown in hyperglycemic conditions, the glycogen content was increased. The increase in glycogen content was associated with an increase in GS without changes in GP levels. In RPE form human donors, the muscle GS isoform but not the liver GS isoform was detected. Regarding GP, the muscle and brain isoform of GP but not the liver GP isoform were detected. We conclude that glycogen storage is increased in the RPE of diabetic patients, and it is associated with an increase in GS activity. Further studies aimed at determining the role of glycogen deposits in the pathogenesis of diabetic retinopathy are warranted.
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Affiliation(s)
- Cristina Hernández
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Pg. Vall d'Hebron 119-129, 08035, Barcelona, Spain,
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25
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Saez I, Duran J, Sinadinos C, Beltran A, Yanes O, Tevy MF, Martínez-Pons C, Milán M, Guinovart JJ. Neurons have an active glycogen metabolism that contributes to tolerance to hypoxia. J Cereb Blood Flow Metab 2014; 34:945-55. [PMID: 24569689 PMCID: PMC4050236 DOI: 10.1038/jcbfm.2014.33] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 01/28/2014] [Accepted: 01/29/2014] [Indexed: 01/08/2023]
Abstract
Glycogen is present in the brain, where it has been found mainly in glial cells but not in neurons. Therefore, all physiologic roles of brain glycogen have been attributed exclusively to astrocytic glycogen. Working with primary cultured neurons, as well as with genetically modified mice and flies, here we report that-against general belief-neurons contain a low but measurable amount of glycogen. Moreover, we also show that these cells express the brain isoform of glycogen phosphorylase, allowing glycogen to be fully metabolized. Most importantly, we show an active neuronal glycogen metabolism that protects cultured neurons from hypoxia-induced death and flies from hypoxia-induced stupor. Our findings change the current view of the role of glycogen in the brain and reveal that endogenous neuronal glycogen metabolism participates in the neuronal tolerance to hypoxic stress.
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Affiliation(s)
- Isabel Saez
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
| | - Jordi Duran
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | | | - Antoni Beltran
- Metabolomics Platform, CIBERDEM, Reus, Spain
- Center for Omic Sciences (COS), Universitat Rovira i Virgili, Reus, Spain
- Institut d'Investigació Biomédica Pere Virgili (IISPV), Reus, Spain
| | - Oscar Yanes
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
- Metabolomics Platform, CIBERDEM, Reus, Spain
- Center for Omic Sciences (COS), Universitat Rovira i Virgili, Reus, Spain
- Institut d'Investigació Biomédica Pere Virgili (IISPV), Reus, Spain
| | - María F Tevy
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | | | - Marco Milán
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Joan J Guinovart
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
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26
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Laforin-malin complex degrades polyglucosan bodies in concert with glycogen debranching enzyme and brain isoform glycogen phosphorylase. Mol Neurobiol 2013; 49:645-57. [PMID: 24068615 DOI: 10.1007/s12035-013-8546-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 08/27/2013] [Indexed: 10/26/2022]
Abstract
In Lafora disease (LD), the deficiency of either EPM2A or NHLRC1, the genes encoding the phosphatase laforin and E3 ligase, respectively, causes massive accumulation of less-branched glycogen inclusions, known as Lafora bodies, also called polyglucosan bodies (PBs), in several types of cells including neurons. The biochemical mechanism underlying the PB accumulation, however, remains undefined. We recently demonstrated that laforin is a phosphatase of muscle glycogen synthase (GS1) in PBs, and that laforin recruits malin, together reducing PBs. We show here that accomplishment of PB degradation requires a protein assembly consisting of at least four key enzymes: laforin and malin in a complex, and the glycogenolytic enzymes, glycogen debranching enzyme 1 (AGL1) and brain isoform glycogen phosphorylase (GPBB). Once GS1-synthesized polyglucosan accumulates into PBs, laforin recruits malin to the PBs where laforin dephosphorylates, and malin degrades the GS1 in concert with GPBB and AGL1, resulting in a breakdown of polyglucosan. Without fountional laforin-malin complex assembled on PBs, GPBB and AGL1 together are unable to efficiently breakdown polyglucosan. All these events take place on PBs and in cytoplasm. Deficiency of each of the four enzymes causes PB accumulation in the cytoplasm of affected cells. Demonstration of the molecular mechanisms underlying PB degradation lays a substantial biochemical foundation that may lead to understanding how PB metabolizes and why mutations of either EPM2A or NHLRC1 in humans cause LD. Mutations in AGL1 or GPBB may cause diseases related to PB accumulation.
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DiNuzzo M, Mangia S, Maraviglia B, Giove F. Regulatory mechanisms for glycogenolysis and K+ uptake in brain astrocytes. Neurochem Int 2013; 63:458-64. [PMID: 23968961 DOI: 10.1016/j.neuint.2013.08.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 11/29/2022]
Abstract
Recent advances in brain energy metabolism support the notion that glycogen in astrocytes is necessary for the clearance of neuronally-released K(+) from the extracellular space. However, how the multiple metabolic pathways involved in K(+)-induced increase in glycogen turnover are regulated is only partly understood. Here we summarize the current knowledge about the mechanisms that control glycogen metabolism during enhanced K(+) uptake. We also describe the action of the ubiquitous Na(+)/K(+) ATPase for both ion transport and intracellular signaling cascades, and emphasize its importance in understanding the complex relation between glycogenolysis and K(+) uptake.
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Affiliation(s)
- Mauro DiNuzzo
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy.
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Obel LF, Müller MS, Walls AB, Sickmann HM, Bak LK, Waagepetersen HS, Schousboe A. Brain glycogen-new perspectives on its metabolic function and regulation at the subcellular level. FRONTIERS IN NEUROENERGETICS 2012; 4:3. [PMID: 22403540 PMCID: PMC3291878 DOI: 10.3389/fnene.2012.00003] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 02/13/2012] [Indexed: 11/14/2022]
Abstract
Glycogen is a complex glucose polymer found in a variety of tissues, including brain, where it is localized primarily in astrocytes. The small quantity found in brain compared to e.g., liver has led to the understanding that brain glycogen is merely used during hypoglycemia or ischemia. In this review evidence is brought forward highlighting what has been an emerging understanding in brain energy metabolism: that glycogen is more than just a convenient way to store energy for use in emergencies—it is a highly dynamic molecule with versatile implications in brain function, i.e., synaptic activity and memory formation. In line with the great spatiotemporal complexity of the brain and thereof derived focus on the basis for ensuring the availability of the right amount of energy at the right time and place, we here encourage a closer look into the molecular and subcellular mechanisms underlying glycogen metabolism. Based on (1) the compartmentation of the interconnected second messenger pathways controlling glycogen metabolism (calcium and cAMP), (2) alterations in the subcellular location of glycogen-associated enzymes and proteins induced by the metabolic status and (3) a sequential component in the intermolecular mechanisms of glycogen metabolism, we suggest that glycogen metabolism in astrocytes is compartmentalized at the subcellular level. As a consequence, the meaning and importance of conventional terms used to describe glycogen metabolism (e.g., turnover) is challenged. Overall, this review represents an overview of contemporary knowledge about brain glycogen and its metabolism and function. However, it also has a sharp focus on what we do not know, which is perhaps even more important for the future quest of uncovering the roles of glycogen in brain physiology and pathology.
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Affiliation(s)
- Linea F Obel
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen Copenhagen, Denmark
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Kelsall IR, Voss M, Munro S, Cuthbertson DJR, Cohen PTW. R3F, a novel membrane-associated glycogen targeting subunit of protein phosphatase 1 regulates glycogen synthase in astrocytoma cells in response to glucose and extracellular signals. J Neurochem 2011; 118:596-610. [DOI: 10.1111/j.1471-4159.2011.07345.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
In the present paper we formulate the hypothesis that brain glycogen is a critical determinant in the modulation of carbohydrate supply at the cellular level. Specifically, we propose that mobilization of astrocytic glycogen after an increase in AMP levels during enhanced neuronal activity controls the concentration of glucose phosphates in astrocytes. This would result in modulation of glucose phosphorylation by hexokinase and upstream cell glucose uptake. This mechanism would favor glucose channeling to activated neurons, supplementing the already rich neuron-astrocyte metabolic and functional partnership with important implications for the energy compounds used to sustain neuronal activity. The hypothesis is based on recent modeling evidence suggesting that rapid glycogen breakdown can profoundly alter the short-term kinetics of glucose delivery to neurons and astrocytes. It is also based on review of the literature relevant to glycogen metabolism during physiological brain activity, with an emphasis on the metabolic pathways identifying both the origin and the fate of this glucose reserve.
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Affiliation(s)
- Mauro DiNuzzo
- Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
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DiNuzzo M, Mangia S, Maraviglia B, Giove F. Glycogenolysis in astrocytes supports blood-borne glucose channeling not glycogen-derived lactate shuttling to neurons: evidence from mathematical modeling. J Cereb Blood Flow Metab 2010; 30:1895-904. [PMID: 20827264 PMCID: PMC3002884 DOI: 10.1038/jcbfm.2010.151] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this article, we examined theoretically the role of human cerebral glycogen in buffering the metabolic requirement of a 360-second brain stimulation, expanding our previous modeling study of neurometabolic coupling. We found that glycogen synthesis and degradation affects the relative amount of glucose taken up by neurons versus astrocytes. Under conditions of 175:115 mmol/L (∼1.5:1) neuronal versus astrocytic activation-induced Na(+) influx ratio, ∼12% of astrocytic glycogen is mobilized. This results in the rapid increase of intracellular glucose-6-phosphate level on stimulation and nearly 40% mean decrease of glucose flow through hexokinase (HK) in astrocytes via product inhibition. The suppression of astrocytic glucose phosphorylation, in turn, favors the channeling of glucose from interstitium to nearby activated neurons, without a critical effect on the concurrent intercellular lactate trafficking. Under conditions of increased neuronal versus astrocytic activation-induced Na(+) influx ratio to 190:65 mmol/L (∼3:1), glycogen is not significantly degraded and blood glucose is primarily taken up by neurons. These results support a role for astrocytic glycogen in preserving extracellular glucose for neuronal utilization, rather than providing lactate to neurons as is commonly accepted by the current 'thinking paradigm'. This might be critical in subcellular domains during functional conditions associated with fast energetic demands.
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Affiliation(s)
- Mauro DiNuzzo
- Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
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Expression of glycogen phosphorylase isoforms in cultured muscle from patients with McArdle's disease carrying the p.R771PfsX33 PYGM mutation. PLoS One 2010; 5. [PMID: 20957198 PMCID: PMC2950139 DOI: 10.1371/journal.pone.0013164] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 09/11/2010] [Indexed: 11/24/2022] Open
Abstract
Background Mutations in the PYGM gene encoding skeletal muscle glycogen phosphorylase (GP) cause a metabolic disorder known as McArdle's disease. Previous studies in muscle biopsies and cultured muscle cells from McArdle patients have shown that PYGM mutations abolish GP activity in skeletal muscle, but that the enzyme activity reappears when muscle cells are in culture. The identification of the GP isoenzyme that accounts for this activity remains controversial. Methodology/Principal Findings In this study we present two related patients harbouring a novel PYGM mutation, p.R771PfsX33. In the patients' skeletal muscle biopsies, PYGM mRNA levels were ∼60% lower than those observed in two matched healthy controls; biochemical analysis of a patient muscle biopsy resulted in undetectable GP protein and GP activity. A strong reduction of the PYGM mRNA was observed in cultured muscle cells from patients and controls, as compared to the levels observed in muscle tissue. In cultured cells, PYGM mRNA levels were negligible regardless of the differentiation stage. After a 12 day period of differentiation similar expression of the brain and liver isoforms were observed at the mRNA level in cells from patients and controls. Total GP activity (measured with AMP) was not different either; however, the active GP activity and immunoreactive GP protein levels were lower in patients' cell cultures. GP immunoreactivity was mainly due to brain and liver GP but muscle GP seemed to be responsible for the differences. Conclusions/Significance These results indicate that in both patients' and controls' cell cultures, unlike in skeletal muscle tissue, most of the protein and GP activities result from the expression of brain GP and liver GP genes, although there is still some activity resulting from the expression of the muscle GP gene. More research is necessary to clarify the differential mechanisms of metabolic adaptations that McArdle cultures undergo in vitro.
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Vinnakota KC, Rusk J, Palmer L, Shankland E, Kushmerick MJ. Common phenotype of resting mouse extensor digitorum longus and soleus muscles: equal ATPase and glycolytic flux during transient anoxia. J Physiol 2010; 588:1961-83. [PMID: 20308252 DOI: 10.1113/jphysiol.2009.185934] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Rates of ATPase and glycolysis are several times faster in actively contracting mouse extensor digitorum longus muscle (EDL) than soleus (SOL), but we find these rates are not distinguishable at rest. We used a transient anoxic perturbation of steady state energy balance to decrease phosphocreatine (PCr) reversibly and to measure the rates of ATPase and of lactate production without muscle activation or contraction. The rate of glycolytic ATP synthesis is less than the ATPase rate, accounting for the continual PCr decrease during anoxia in both muscles. We fitted a mathematical model validated with properties of enzymes and solutes measured in vitro and appropriate for the transient perturbation of these muscles to experimental data to test whether the model accounts for the results. Simulations showed equal rates of ATPase and lactate production in both muscles. ATPase controls glycolytic flux by feedback from its products. Adenylate kinase function is critical because a rise in [AMP] is necessary to activate glycogen phosphorylase. ATPase is the primary source of H+ production. The sum of contributions of the 13 reactions of the glycogenolytic and glycolytic network to total proton load is negligible. The stoichiometry of lactate and H+ production is near unity. These results identify a default state of energy metabolism for resting muscle in which there is no difference in the metabolic phenotype of EDL and SOL. Therefore, additional control mechanisms, involving higher ATPase flux and [Ca2+], must exist to explain the well-known difference in glycolytic rates in fast-twitch and slow-twitch muscles in actively contracting muscle.
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Affiliation(s)
- Kalyan C Vinnakota
- University of Washington, Mail Box 357115, Department of Radiology, 1959 NE Pacific Avenue, HSC AA010, Seattle, WA 09105-7115, USA
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Sickmann HM, Walls AB, Schousboe A, Bouman SD, Waagepetersen HS. Functional significance of brain glycogen in sustaining glutamatergic neurotransmission. J Neurochem 2009; 109 Suppl 1:80-6. [DOI: 10.1111/j.1471-4159.2009.05915.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Montori-Grau M, Minor R, Lerin C, Allard J, Garcia-Martinez C, de Cabo R, Gómez-Foix AM. Effects of aging and calorie restriction on rat skeletal muscle glycogen synthase and glycogen phosphorylase. Exp Gerontol 2009; 44:426-33. [PMID: 19341787 DOI: 10.1016/j.exger.2009.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/18/2009] [Accepted: 03/23/2009] [Indexed: 11/25/2022]
Abstract
Calorie restriction's (CR) effects on age-associated changes in glycogen-metabolizing enzymes were studied in rat soleus (SOL) and tibialis anterior (TA) muscles. Old (24 months) compared to young (6 months) rats maintained ad libitum on a standard diet had reduced glycogen synthase (GS) activity, lower muscle GS protein levels, increased phosphorylation of GS at site 3a with less activation in SOL. Age-associated impairments in GS protein and activation-phosphorylation were also shown in TA. There was an age-associated reduction in glycogen phosphorylase (GP) activity level in SOL, while brain/muscle isoforms (B/M) of GP protein levels were higher. GP activity and protein levels were preserved, but GP was inactivated in TA with age. Glycogen content was unchanged in both muscles. CR did not alter GS or GP activity/protein levels in young rats. CR hindered age-related decreases in GS activity/protein, unrelated to GS mRNA levels, and GS inactivation-phosphorylation; not on GP. In older rats, CR enhanced glycogen accumulation in SOL. Short-term fasting did not recapitulate CR effects in old rats. Thus, the predominant age-associated impairments on skeletal muscle GS and GP activities occur in the oxidative SOL muscle of rats, and CR can attenuate the loss of GS activity/activation and stimulate glycogen accumulation.
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Affiliation(s)
- Marta Montori-Grau
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Departament de Bioquímica i Biologia Molecular, IBUB, Facultat de Biologia, Universitat de Barcelona, Diagonal, 645, 08028 Barcelona, Spain
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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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37
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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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38
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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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39
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Effect of Diabetes on Glycogen Metabolism in Rat Retina. Neurochem Res 2008; 33:1301-8. [DOI: 10.1007/s11064-007-9583-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 12/26/2007] [Indexed: 10/22/2022]
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40
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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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41
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Rothermel A, Weigel W, Pfeiffer-Guglielmi B, Hamprecht B, Robitzki AA. Immunocytochemical analysis of glycogen phosphorylase isozymes in the developing and adult retina of the domestic chicken (Gallus domesticus). Neurochem Res 2007; 33:336-47. [PMID: 17940897 DOI: 10.1007/s11064-007-9477-8] [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: 05/18/2007] [Accepted: 08/15/2007] [Indexed: 11/26/2022]
Abstract
Glycogen is the major energy reserve in neural tissues including the retina. A key-enzyme in glycogen metabolism is glycogen phosphorylase (GP) which exists in three differentially regulated isoforms. By applying isozyme-specific antibodies it could be demonstrated that the GP BB (brain), but not the GP MM (muscle) isoform is expressed in the chicken retina in neuronal and glial (Müller) cells. In the embryonic chicken retina, GP showed a development-dependent expression pattern. Double-labeling experiments with cell type-specific antibodies revealed that GP is expressed in various layers of the retina some of which, e.g., the photoreceptor inner segments, are known to be sites of high energy consumption. This suggests important roles of GP BB, and therefore glycogen, in early differentiation, spontaneous wave generation and in formation and stabilization of synapses.
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Affiliation(s)
- Andrée Rothermel
- Molekularbiologisch-biochemische Prozesstechnik, Biotechnologisch-Biomedizinisches Zentrum, Universität Leipzig, Deutscher Platz 5, Leipzig 04103, Germany
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42
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Selivanov VA, de Atauri P, Centelles JJ, Cadefau J, Parra J, Cussó R, Carreras J, Cascante M. The changes in the energy metabolism of human muscle induced by training. J Theor Biol 2007; 252:402-10. [PMID: 17996255 DOI: 10.1016/j.jtbi.2007.09.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 09/21/2007] [Accepted: 09/26/2007] [Indexed: 11/26/2022]
Abstract
The biochemical effects of training programmes have been studied with a kinetic model of central metabolism, using enzyme activities and metabolite concentrations measured at rest and after 30 s maximum-intensity exercise, collected before and after long and short periods of training, which differed only by the duration of the rest intervals. After short periods of training the glycolytic flux at rest was three times higher than it had been before training, whereas during exercise the flux and energy consumption remained the same as before training. Long periods of training had less effect on the glycolytic flux at rest, but increased it in response to exercise, increasing the contribution of oxidative phosphorylation.
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Affiliation(s)
- V A Selivanov
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Associated Unit to CSIC, Institute of Biomedicine of University of Barcelona and CeRQT at Barcelona Scientific Park, Diagonal 645, 08028 Barcelona, Spain
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43
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Pfeiffer-Guglielmi B, Francke M, Reichenbach A, Hamprecht B. Glycogen phosphorylase isozymes and energy metabolism in the rat peripheral nervous system--an immunocytochemical study. Brain Res 2006; 1136:20-7. [PMID: 17239832 DOI: 10.1016/j.brainres.2006.12.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 12/07/2006] [Accepted: 12/08/2006] [Indexed: 11/20/2022]
Abstract
Glycogen represents the major brain energy reserve which is located mainly in astrocytes. Though the role of brain glycogen has drawn increasing attention, little is known about glycogen metabolism in the peripheral nervous system. In the present work, we have demonstrated immunocytochemically the ubiquitous presence of glycogen phosphorylase (GP), one of the major control sites in glycogen metabolism, in the axons of rat spinal and sciatic nerves, but not in Schwann cells. Application of isozyme-specific antibodies revealed the presence of the GP BB (brain) isoform, but not the MM (muscle) isoform. This is in accord with previous results demonstrating the presence of isoform BB, but not MM, in the few GP-containing brain and spinal cord neurons and in vagus nerve axons. In contrast, brain astrocytes express both isoforms. As GP BB is mainly regulated by the cellular AMP level, a special role of glycogen in the energization of the nerve axons is suggested. The cellular locations of hexokinase, pyruvate dehydrogenase and glucose transporters are discussed in respect to possible metabolic roles of glycogen in peripheral nerves.
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44
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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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45
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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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47
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Pfeiffer-Guglielmi B, Bröer S, Bröer A, Hamprecht B. Isozyme pattern of glycogen phosphorylase in the rat nervous system and rat astroglia-rich primary cultures: electrophoretic and polymerase chain reaction studies. Neurochem Res 2000; 25:1485-91. [PMID: 11071367 DOI: 10.1023/a:1007676109206] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Of the three isozymes of glycogen phosphorylase (GP) known, the brain (B) and muscle (M) isoforms have been reported to occur in brain. We investigated the regional and cellular occurrence of the three isozymes in various parts of the rat nervous system, fetal brain and astroglia-rich primary cultures by means of electrophoresis of native proteins with subsequent activity stain and by reverse transcriptase polymerase chain reaction. In the cortex, cerebellum, olfactory bulb, brainstem, spinal cord and dorsal root ganglia, both mRNA and enzyme protein were found for the B and M isozymes. In addition, the liver (L) isoform mRNA was detected in fetal brain and cultured astrocytes. Our studies indicate that there is no regional difference in distribution pattern between brain regions, spinal cord and dorsal root ganglia. In immature brain and cultured glial cells, the additional presence of the L isozyme is possible. These results support the idea that astrocytes express two or even three GP isozymes simultaneously.
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Burwinkel B, Bakker HD, Herschkovitz E, Moses SW, Shin YS, Kilimann MW. Mutations in the liver glycogen phosphorylase gene (PYGL) underlying glycogenosis type VI. Am J Hum Genet 1998; 62:785-91. [PMID: 9529348 PMCID: PMC1377030 DOI: 10.1086/301790] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Deficiency of glycogen phosphorylase in the liver gives rise to glycogen-storage disease type VI (Hers disease; MIM 232700). We report the identification of the first mutations in PYGL, the gene encoding the liver isoform of glycogen phosphorylase, in three patients with Hers disease. These are two splice-site mutations and two missense mutations. A mutation of the 5' splice-site consensus of intron 14 causes the retention of intron 14 and the utilization of two illegitimate 5' splice sites, whereas a mutation of the 3' splice-site consensus of intron 4 causes the skipping of exon 5. Two missense mutations, N338S and N376K, both cause nonconservative replacements of amino acids that are absolutely conserved even in yeast and bacterial phosphorylases. We also report corrections of the PYGL coding sequence, sequence polymorphisms, and a partial PYGL gene structure with introns in the same positions as in PYGM, the gene of the muscle isoform of phosphorylase. Our findings demonstrate that PYGL mutations cause Hers disease, and they may improve laboratory diagnosis of deficiencies of the liver phosphorylase system.
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Affiliation(s)
- B Burwinkel
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
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