1
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Ma ZW, Mou JY, Yuan Q, Wang ZY, Liu QH, Deng B, Zhang YD, Tang DQ, Wang L. Molecular exploration of the diurnal alteration of glycogen structural fragility and stability in time-restricted-feeding mouse liver. Int J Biol Macromol 2024; 277:134225. [PMID: 39074710 DOI: 10.1016/j.ijbiomac.2024.134225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 07/23/2024] [Accepted: 07/26/2024] [Indexed: 07/31/2024]
Abstract
The structure of glycogen α particles in healthy mouse liver has two states: stability and fragility. In contrast, glycogen α particles in diabetic liver present consistent fragility, which may exacerbate hyperglycemia. Currently, the molecular mechanism behind glycogen structural alteration is still unclear. In this study, we characterized the fine molecular structure of liver glycogen α particles in healthy mice under time-restricted feeding (TRF) mode during a 24-h cycle. Then, differentially expressed genes (DEGs) in the liver during daytime and nighttime were revealed via transcriptomics, which identified that the key downregulated DEGs were mainly related to insulin secretion in daytime. Furthermore, GO annotation and KEGG pathway enrichment found that negative regulation of the glycogen catabolic process and insulin secretion process were significantly downregulated in the daytime. Therefore, transcriptomic analyses indicated that the structural stability of glycogen α particles might be correlated with the glycogen degradation process via insulin secretion downregulation. Further molecular experiments confirmed the significant upregulation of glycogen phosphorylase (PYGL), phosphorylated PYGL (p-PYGL), and glycogen debranching enzyme (AGL) at the protein level during the daytime. Overall, we concluded that the downregulation of insulin secretion in the daytime under TRF mode facilitated glycogenolysis, contributing to the structural stability of glycogen α-particles.
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Affiliation(s)
- Zhang-Wen Ma
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China; Laboratory Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China; State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Taipa, Macau SAR, China
| | - Jing-Yi Mou
- Department of Clinical Medicine, School of The First Clinical Medicine, Xuzhou Medical University, Xuzhou, China; Department of Thyroid and Breast Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; Department of Breast Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Quan Yuan
- Department of Intelligent Medical Engineering, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Zi-Yi Wang
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Qing-Hua Liu
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Taipa, Macau SAR, China
| | - Bin Deng
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yu-Dong Zhang
- Department of Clinical Medicine, School of The First Clinical Medicine, Xuzhou Medical University, Xuzhou, China.
| | - Dao-Quan Tang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China.
| | - Liang Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China; Laboratory Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China; School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Queensland, Australia; Centre for Precision Health, School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia 6027, Australia.
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2
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Nielsen J. Beyond homogenates: New tool available for estimating glycogen's numerical subcellular distribution. J Gen Physiol 2024; 156:e202413607. [PMID: 38980208 PMCID: PMC11232886 DOI: 10.1085/jgp.202413607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024] Open
Abstract
This Commentary discusses the implications of a recent JGP study (Ríos et al. https://www.doi.org/10.1085/jgp.202413595) demonstrating an AI model to quantify glycogen granules.
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Affiliation(s)
- Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
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3
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Liu X, Gilbert RG. Normal and abnormal glycogen structure - A review. Carbohydr Polym 2024; 338:122195. [PMID: 38763710 DOI: 10.1016/j.carbpol.2024.122195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/18/2024] [Accepted: 04/20/2024] [Indexed: 05/21/2024]
Abstract
Glycogen, a complex branched glucose polymer, is found in animals and bacteria, where it serves as an energy storage molecule. It has linear (1 → 4)-α glycosidic bonds between anhydroglucose monomer units, with branch points connected by (1 → 6)-α bonds. Individual glycogen molecules are referred to as β particles. In organs like the liver and heart, these β particles can bind into larger aggregate α particles, which exhibit a rosette-like morphology. The mechanisms and bonding underlying the aggregation process are not fully understood. For example, mammalian liver glycogen has been observed to be molecularly fragile under certain conditions, such as glycogen from diabetic livers fragmenting when exposed to dimethyl sulfoxide (DMSO), while glycogen from healthy livers is much less fragile; this indicates some difference, as yet unknown, in the bonding between β particles in healthy and diabetic glycogen. This fragility may have implications for blood sugar regulation, especially in pathological conditions such as diabetes.
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Affiliation(s)
- Xin Liu
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Zhongshan Biological Breeding Laboratory, and Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Centre for Nutrition & Food Sciences, Queensland Alliance for Agriculture & Food Innovations (QAAFI), The University of Queensland, QLD 4072, Australia
| | - Robert G Gilbert
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Zhongshan Biological Breeding Laboratory, and Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Centre for Nutrition & Food Sciences, Queensland Alliance for Agriculture & Food Innovations (QAAFI), The University of Queensland, QLD 4072, Australia.
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4
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Tan X, Wang Z, Cheung U, Hu Z, Liu Q, Wang L, Sullivan MA, Cozzolino D, Gilbert RG. Liver glycogen fragility in the presence of hydrogen-bond breakers. Int J Biol Macromol 2024; 268:131741. [PMID: 38649083 DOI: 10.1016/j.ijbiomac.2024.131741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/19/2024] [Indexed: 04/25/2024]
Abstract
Glycogen, a complex branched glucose polymer, is responsible for sugar storage in blood glucose homeostasis. It comprises small β particles bound together into composite α particles. In diabetic livers, α particles are fragile, breaking apart into smaller particles in dimethyl sulfoxide, DMSO; they are however stable in glycogen from healthy animals. We postulate that the bond between β particles in α particles involves hydrogen bonding. Liver-glycogen fragility in normal and db/db mice (an animal model for diabetes) is compared using various hydrogen-bond breakers (DMSO, guanidine and urea) at different temperatures. The results showed different degrees of α-particle disruption. Disrupted glycogen showed changes in the mid-infra-red spectrum that are related to hydrogen bonds. While glycogen α-particles are only fragile under harsh, non-physiological conditions, these results nevertheless imply that the bonding between β particles in α particles is different in diabetic livers compared to healthy, and is probably associated with hydrogen bonding.
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Affiliation(s)
- Xinle Tan
- Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Ziyi Wang
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Ut Cheung
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Zhenxia Hu
- Department of Pharmacy, Shanghai Public Health Clinical Center, Fudan University, Shanghai, China.
| | - Qinghua Liu
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Taipa, Macau SAR 999078, China
| | - Liang Wang
- Laboratory Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Mitchell A Sullivan
- Glycation and Diabetes Group, Mater Research Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland, 4012, Australia.
| | - Daniel Cozzolino
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Robert G Gilbert
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia; Jiangsu Key Laboratory of Crop Genetics and Physiology/State Key Laboratory of Hybrid Rice, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China.
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5
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Liu X, Zhang P, Gilbert RG. Formation mechanism of α particles in glycogen: Testing the budding hypothesis by Monte-Carlo simulation. Int J Biol Macromol 2024; 263:130332. [PMID: 38401580 DOI: 10.1016/j.ijbiomac.2024.130332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/15/2024] [Accepted: 02/19/2024] [Indexed: 02/26/2024]
Abstract
Glycogen, a complex branched glucose polymer and a blood-sugar reservoir in animals, comprises small β particles joined together into composite α particles. In diabetic animals, α particles fragment more easily than those in healthy animals. Finding evidence for or against postulated mechanisms for α-particle formation is thus important for diabetes research. Insight into this is obtained here using Monte-Carlo simulations, including addition and loss of glucose monomer, branching and debranching, based on earlier simulations which were in acceptable agreement with experiment [Zhang et al., Int J Biol Macromolecules 2018, 116, 264]. One postulated mechanism for α-particle formation is "budding": occasionally a glucan chain temporarily protrudes from the particle, and if its growing end is sufficiently far from its parent particle, it propagates to a new linked particle. We tested this by simulations in which an "artificial" bud (a chain extending well outside the average particle radius) is added to a glycogen molecule in a dynamic steady state, and the system allowed to evolve. In some simulations, the particle reached a new steady state having an irregular dumbbell shape: a rudimentary α particle. Thus 'budding' is a possible mechanism for α particles to form. If no simulations had shown this behaviour, it would have refuted the postulate.
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Affiliation(s)
- Xin Liu
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, Jiangsu Province, China; Co-Innovation Centre for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, Jiangsu Province, China; Centre for Nutrition & Food Sciences, Queensland Alliance for Agriculture & Food Innovations (QAAFI), The University of Queensland, QLD 4072, Australia
| | - Peng Zhang
- School of Electronic Engineering, Tongling University, Tongling 244061, PR China
| | - Robert G Gilbert
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, Jiangsu Province, China; Co-Innovation Centre for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, Jiangsu Province, China; Centre for Nutrition & Food Sciences, Queensland Alliance for Agriculture & Food Innovations (QAAFI), The University of Queensland, QLD 4072, Australia.
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6
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Żołnierkiewicz O, Rogacka D. Hyperglycemia - A culprit of podocyte pathology in the context of glycogen metabolism. Arch Biochem Biophys 2024; 753:109927. [PMID: 38350532 DOI: 10.1016/j.abb.2024.109927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/31/2024] [Accepted: 02/10/2024] [Indexed: 02/15/2024]
Abstract
Prolonged disruption in the balance of glucose can result in metabolic disorders. The kidneys play a significant role in regulating blood glucose levels. However, when exposed to chronic hyperglycemia, the kidneys' ability to handle glucose metabolism may be impaired, leading to an accumulation of glycogen. Earlier studies have shown that there can be a significant increase in glucose storage in the form of glycogen in the kidneys in diabetes. Podocytes play a crucial role in maintaining the integrity of filtration barrier. In diabetes, exposure to elevated glucose levels can lead to significant metabolic and structural changes in podocytes, contributing to kidney damage and the development of diabetic kidney disease. The accumulation of glycogen in podocytes is not a well-established phenomenon. However, a recent study has demonstrated the presence of glycogen granules in podocytes. This review delves into the intricate connections between hyperglycemia and glycogen metabolism within the context of the kidney, with special emphasis on podocytes. The aberrant storage of glycogen has the potential to detrimentally impact podocyte functionality and perturb their structural integrity. This review provides a comprehensive analysis of the alterations in cellular signaling pathways that may potentially lead to glycogen overproduction in podocytes.
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Affiliation(s)
- Olga Żołnierkiewicz
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Wita Stwosza 63, 80-308, Gdansk, Poland
| | - Dorota Rogacka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Wita Stwosza 63, 80-308, Gdansk, Poland; University of Gdansk, Faculty of Chemistry, Department of Molecular Biotechnology, Wita Stwosza 63, 80-308, Gdansk, Poland.
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7
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Rousset Y, Ebenhöh O, Raguin A. Stochastic modelling of a three-dimensional glycogen granule synthesis and impact of the branching enzyme. PLoS Comput Biol 2023; 19:e1010694. [PMID: 37205718 DOI: 10.1371/journal.pcbi.1010694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 03/25/2023] [Indexed: 05/21/2023] Open
Abstract
In humans, glycogen storage diseases result from metabolic inborn errors, and can lead to severe phenotypes and lethal conditions. Besides these rare diseases, glycogen is also associated to widely spread societal burdens such as diabetes. Glycogen is a branched glucose polymer synthesised and degraded by a complex set of enzymes. Over the past 50 years, the structure of glycogen has been intensively investigated. Yet, the interplay between the detailed three-dimensional glycogen structure and the related enzyme activity is only partially characterised and still to be fully understood. In this article, we develop a stochastic coarse-grained and spatially resolved model of branched polymer biosynthesis following a Gillespie algorithm. Our study largely focusses on the role of the branching enzyme, and first investigates the properties of the model with generic parameter values, before comparing it to in vivo experimental data in mice. It arises that the ratio of glycogen synthase over branching enzyme reaction rates drastically impacts the structure of the granule. We deeply investigate the mechanism of branching and parametrise it using distinct lengths. Not only do we consider various possible sets of values for these lengths, but also distinct rules to apply them. We show how combining various values for these lengths finely tunes glycogen macromolecular structure. Comparing the model with experimental data confirms that we can accurately reproduce glycogen chain length distributions in wild type mice. Additional granule properties obtained for this fit are also in good agreement with typically reported values in the experimental literature. Nonetheless, we find that the mechanism of branching must be more flexible than usually reported. Overall, our model provides a theoretical basis to quantify the effect that single enzymatic parameters, in particular of the branching enzyme, have on the chain length distribution. Our generic model and methods can be applied to any glycogen data set, and could in particular contribute to characterise the mechanisms responsible for glycogen storage disorders.
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Affiliation(s)
- Yvan Rousset
- Institute for Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf, Germany
- Institute for Computational Cell Biology, Heinrich-Heine University, Düsseldorf, Germany
| | - Oliver Ebenhöh
- Institute for Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine University, Düsseldorf, Germany
| | - Adélaïde Raguin
- Institute for Computational Cell Biology, Heinrich-Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine University, Düsseldorf, Germany
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8
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Li F, Wang MM, Liu QH, Ma ZW, Wang JJ, Wang ZY, Tang JW, Lyu JW, Zhu ZB, Wang L. Molecular mechanisms of glycogen particle assembly in Escherichia coli. Carbohydr Polym 2023; 299:120200. [PMID: 36876811 DOI: 10.1016/j.carbpol.2022.120200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/02/2022] [Accepted: 10/05/2022] [Indexed: 11/09/2022]
Abstract
It has been reported that glycogen in Escherichia coli has two structural states, that is, fragility and stability, which alters dynamically. However, molecular mechanisms behind the structural alterations are not fully understood. In this study, we focused on the potential roles of two important glycogen degradation enzymes, glycogen phosphorylase (glgP) and glycogen debranching enzyme (glgX), in glycogen structural alterations. The fine molecular structure of glycogen particles in Escherichia coli and three mutants (ΔglgP, ΔglgX and ΔglgP/ΔglgX) were examined, which showed that glycogen in E. coli ΔglgP and E. coli ΔglgP/ΔglgX were consistently fragile while being consistently stable in E. coli ΔglgX, indicating the dominant role of GP in glycogen structural stability control. In sum, our study concludes that glycogen phosphorylase is essential in glycogen structural stability, leading to molecular insights into structural assembly of glycogen particles in E. coli.
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Affiliation(s)
- Fen Li
- Laboratory Medicine, The Fifth People's Hospital of Huai'an, Huai'an, Jiangsu Province, China
| | - Meng-Meng Wang
- Department of Pharmacy, Qingdao Eighth People's Hospital, Qingdao, Shandong Province, China; Department of Pharmaceutical Analysis, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Qing-Hua Liu
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Taipa, Macao SAR, China
| | - Zhang-Wen Ma
- Department of Pharmaceutical Analysis, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Jun-Jiao Wang
- Department of Intelligent Medical Engineering, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Zi-Yi Wang
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Jia-Wei Tang
- Department of Intelligent Medical Engineering, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Jing-Wen Lyu
- Laboratory Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong Province, China
| | - Zuo-Bin Zhu
- Department of Genetics, School of Life Sciences, Xuzhou Medical University, Xuzhou, Jiangsu Province, China.
| | - Liang Wang
- Laboratory Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong Province, China.
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9
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Wang Z, Min X, Hu Z, Sullivan MA, Tang Y, Wang L, Gilbert RG, Shi C, Deng B. The fragility of liver glycogen from humans with type 2 diabetes: A pilot study. Int J Biol Macromol 2022; 221:83-90. [PMID: 36075306 DOI: 10.1016/j.ijbiomac.2022.08.212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/27/2022] [Accepted: 08/31/2022] [Indexed: 11/05/2022]
Abstract
Liver glycogen is a highly branched glucose polymer found as β particles (~20 nm in diameter), which can bind together into larger composite α particles. Hepatic α particles have been shown to be structurally fragile (breaking up into smaller particles in certain solvents) in mouse models of diabetes; if occurring in vivo, the resulting small glycogen particles could exacerbate the poor blood-sugar homeostasis characteristic of the disease. Here we tested if this α-particle fragility also occurred in liver glycogen obtained from humans with diabetes. It was found that liver glycogen from diabetic humans was indeed more fragile than from non-diabetic humans, which was also seen in the mouse experiments we ran in parallel. Proteomic analysis revealed three candidate proteins from differentially expressed glycogen proteins (Diabetes/ Non-diabetes) in both human and mouse groups. Identifying these proteins may give clues to the binding mechanism that holds together α particles together, which, being different in diabetic glycogen, is relevant to diabetes prevention and management.
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Affiliation(s)
- Ziyi Wang
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Xiaobo Min
- Department of Hepatobiliary Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Zhenxia Hu
- Department of Pharmacy, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, China
| | - Mitchell A Sullivan
- Glycation and Diabetes, Mater Research Institute - The University of Queensland, Translational Research Institute, Brisbane, QLD 4102, Australia
| | - Yong Tang
- Department of Hepatobiliary Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Liang Wang
- Laboratory Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong Province 510080, China
| | - Robert G Gilbert
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia; Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China
| | - Chen Shi
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| | - Bin Deng
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
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10
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Fastman NM, Liu Y, Ramanan V, Merritt H, Ambing E, DePaoli-Roach AA, Roach PJ, Hurley TD, Mellem KT, Ullman JC, Green E, Morgans D, Tzitzilonis C. The structural mechanism of human glycogen synthesis by the GYS1-GYG1 complex. Cell Rep 2022; 40:111041. [PMID: 35793618 DOI: 10.1016/j.celrep.2022.111041] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/15/2022] [Accepted: 06/11/2022] [Indexed: 11/03/2022] Open
Abstract
Glycogen is the primary energy reserve in mammals, and dysregulation of glycogen metabolism can result in glycogen storage diseases (GSDs). In muscle, glycogen synthesis is initiated by the enzymes glycogenin-1 (GYG1), which seeds the molecule by autoglucosylation, and glycogen synthase-1 (GYS1), which extends the glycogen chain. Although both enzymes are required for proper glycogen production, the nature of their interaction has been enigmatic. Here, we present the human GYS1:GYG1 complex in multiple conformations representing different functional states. We observe an asymmetric conformation of GYS1 that exposes an interface for close GYG1 association, and propose this state facilitates handoff of the GYG1-associated glycogen chain to a GYS1 subunit for elongation. Full activation of GYS1 widens the GYG1-binding groove, enabling GYG1 release concomitant with glycogen chain growth. This structural mechanism connecting chain nucleation and extension explains the apparent stepwise nature of glycogen synthesis and suggests distinct states to target for GSD-modifying therapeutics.
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Affiliation(s)
- Nathan M Fastman
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Yuxi Liu
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Vyas Ramanan
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Hanne Merritt
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Eileen Ambing
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Anna A DePaoli-Roach
- Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46220, USA
| | - Peter J Roach
- Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46220, USA
| | - Thomas D Hurley
- Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46220, USA
| | - Kevin T Mellem
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Julie C Ullman
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Eric Green
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - David Morgans
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA
| | - Christos Tzitzilonis
- Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA.
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11
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Wang Z, Hu Z, Deng B, Gilbert RG, Sullivan MA. The effect of high-amylose resistant starch on the glycogen structure of diabetic mice. Int J Biol Macromol 2022; 200:124-131. [PMID: 34968551 DOI: 10.1016/j.ijbiomac.2021.12.071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/24/2021] [Accepted: 12/11/2021] [Indexed: 12/13/2022]
Abstract
Glycogen is a complex branched glucose polymer found in many tissues and acts as a blood-glucose buffer. In the liver, smaller β glycogen particles can bind into larger composite α particles. In mouse models of diabetes, these liver glycogen particles are molecularly fragile, breaking up into smaller particles in the presence of solvents such as dimethyl sulfoxide (DMSO). If this occurs in vivo, such a rapid enzymatic degradation of these smaller particles into glucose could exacerbate the poor blood-glucose control that is characteristic of the disease. High-amylose resistant starch (RS) can escape digestion in the small intestine and ferment in the large intestine, which elicits positive effects on glycemic response and type 2 diabetes. Here we postulate that RS would help attenuate diabetes-related liver glycogen fragility. Normal maize starch and two types of high-amylose starch were fed to diabetic and non-diabetic mice. Molecular size distributions and chain-length distributions of liver glycogen from both groups were characterized to test glycogen fragility before and after DMSO treatment. Consistent with the hypothesis that high blood glucose is associated with glycogen fragility, a high-amylose RS diet prevented the fragility of liver-glycogen α particles. The diets had no significant effect on the glycogen chain-length distributions.
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Affiliation(s)
- Ziyi Wang
- Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China; School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia; Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Zhenxia Hu
- Department of Pharmacy, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, China
| | - Bin Deng
- Department of Pharmacy, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Robert G Gilbert
- Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, College of Agriculture, Yangzhou University, Yangzhou 225009, China; Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China; School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia; Department of Pharmacy, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| | - Mitchell A Sullivan
- Glycation and Diabetes, Mater Research Institute - The University of Queensland, Translational Research Institute, Brisbane, Qld 4102, Australia.
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12
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Liu QH, Tang JW, Wen PB, Wang MM, Zhang X, Wang L. From Prokaryotes to Eukaryotes: Insights Into the Molecular Structure of Glycogen Particles. Front Mol Biosci 2021; 8:673315. [PMID: 33996916 PMCID: PMC8116748 DOI: 10.3389/fmolb.2021.673315] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 04/07/2021] [Indexed: 12/25/2022] Open
Abstract
Glycogen is a highly-branched polysaccharide that is widely distributed across the three life domains. It has versatile functions in physiological activities such as energy reserve, osmotic regulation, blood glucose homeostasis, and pH maintenance. Recent research also confirms that glycogen plays important roles in longevity and cognition. Intrinsically, glycogen function is determined by its structure that has been intensively studied for many years. The recent association of glycogen α-particle fragility with diabetic conditions further strengthens the importance of glycogen structure in its function. By using improved glycogen extraction procedures and a series of advanced analytical techniques, the fine molecular structure of glycogen particles in human beings and several model organisms such as Escherichia coli, Caenorhabditis elegans, Mus musculus, and Rat rattus have been characterized. However, there are still many unknowns about the assembly mechanisms of glycogen particles, the dynamic changes of glycogen structures, and the composition of glycogen associated proteins (glycogen proteome). In this review, we explored the recent progresses in glycogen studies with a focus on the structure of glycogen particles, which may not only provide insights into glycogen functions, but also facilitate the discovery of novel drug targets for the treatment of diabetes mellitus.
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Affiliation(s)
- Qing-Hua Liu
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau, China.,Faculty of Chinese Medicine, Macau University of Science and Technology, Macau, China
| | - Jia-Wei Tang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Peng-Bo Wen
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Meng-Meng Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Xiao Zhang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Liang Wang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China.,Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
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13
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Optimization of liver glycogen extraction when considering the fine molecular structure. Carbohydr Polym 2021; 261:117887. [PMID: 33766374 DOI: 10.1016/j.carbpol.2021.117887] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/17/2021] [Accepted: 02/28/2021] [Indexed: 12/16/2022]
Abstract
Liver glycogen is a branched glucose polymer that functions as a blood-sugar buffer in animals. Previous studies have shown that glycogen's molecular structure affects its properties. This makes it important to develop a technique that extracts and purifies a representative sample of glycogen. Here we aim to optimize the sucrose density gradient centrifugation method for preserving glycogen's molecular structure by varying the density of the sucrose solution. The preservation of glycogen's structure involves: 1) minimizing molecular damage and 2) obtaining a structurally representative sample of glycogen. The addition of a 10-minute boiling step was also tested as a means for denaturing any glycogen degrading enzymes. Lower sucrose concentrations and the introduction of the boiling step were shown to be beneficial in obtaining a more structurally representative sample, with the preservation of smaller glycogen particles and decreased glycogen chain degradation.
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14
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The dynamic changes of glycogen molecular structure in Escherichia coli BL21(DE3). Carbohydr Polym 2021; 259:117773. [PMID: 33674016 DOI: 10.1016/j.carbpol.2021.117773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/30/2021] [Accepted: 02/02/2021] [Indexed: 01/12/2023]
Abstract
Diurnal alteration of glycogen molecular structure has been identified in healthy mice. Recently, both fragile (disintegration in dimethyl sulfoxide) and stable (not disintegrating in DMSO) glycogen particles were found in Escherichia coli. However, how glycogen structure changes dynamically in E. coli is not clear. The question examined here is whether fragile, stable glycogen α particles occur in bacteria, following a similar pattern as in mice. In this study, we examine the dynamic changes of glycogen molecular structure over 24-h in E. coli BL21(DE3), using transmission electron microscopy, size exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis at representative time points. It was found that glycogen structure was mainly fragile at the synthesis stage and largely stable during the degradation stage. qRT-PCR results indicated that balance of anabolic and catabolic gene expression levels in glycogen metabolism could be a key factor affecting the fragility of glycogen α particles in bacteria.
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15
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Besford QA, Cavalieri F, Caruso F. Glycogen as a Building Block for Advanced Biological Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904625. [PMID: 31617264 DOI: 10.1002/adma.201904625] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/15/2019] [Indexed: 06/10/2023]
Abstract
Biological nanoparticles found in living systems possess distinct molecular architectures and diverse functions. Glycogen is a unique biological polysaccharide nanoparticle fabricated by nature through a bottom-up approach. The biocatalytic synthesis of glycogen has evolved over time to form a nanometer-sized dendrimer-like structure (20-150 nm) with a highly branched surface and a dense core. This makes glycogen markedly different from other natural linear or branched polysaccharides and particularly attractive as a platform for biomedical applications. Glycogen is inherently biodegradable, nontoxic, and can be functionalized with diverse surface and internal motifs for enhanced biofunctional properties. Recently, there has been growing interest in glycogen as a natural alternative to synthetic polymers and nanoparticles in a range of applications. Herein, the recent literature on glycogen in the material-based sciences, including its use as a constituent in biodegradable hydrogels and fibers, drug delivery vectors, tumor targeting and penetrating nanoparticles, immunomodulators, vaccine adjuvants, and contrast agents, is reviewed. The various methods of chemical functionalization and physical assembly of glycogen nanoparticles into multicomponent nanodevices, which advance glycogen toward a functional therapeutic nanoparticle from nature and back again, are discussed in detail.
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Affiliation(s)
- Quinn A Besford
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Francesca Cavalieri
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
- Dipartimento di Scienze e Tecnologie Chimiche, Università degli Studi di Roma Tor Vergata, via della Ricerca Scientifica 1, 00133, Rome, Italy
| | - Frank Caruso
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
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16
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Liu Q, Zhu Z, Wang M, Wang Y, Zhang P, Wang H, Liang M, Li Y, Deng B, Tang D, Gilbert RG, Wang L. Characterization of glycogen molecular structure in the worm Caenorhabditis elegans. Carbohydr Polym 2020; 237:116181. [PMID: 32241425 DOI: 10.1016/j.carbpol.2020.116181] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/13/2020] [Accepted: 03/13/2020] [Indexed: 12/21/2022]
Abstract
Glycogen, a glucose homopolymer with many glucose chains, is the primary blood-sugar reservoir in many organisms. It comprises β particles (∼20 nm) which can bind together to form large α particles with a rosette morphology. When dimethyl sulfoxide (DMSO) is added to glycogen from diabetic livers, α particles break apart to β particles ('fragility'), possibly due to H-bond disruption; this is not seen in healthy livers. Glycogen α and β particles, and α-particle fragility, are observed in mammals and bacteria, and are examined here in the worm Caenorhabditis elegans, with glycogen from two C. elegans strains, cultured in normal and high-glucose conditions. There were mainly β particles, with some large α particles. Most particles were fragile in DMSO. Growing in a high-glucose medium results in more long chains and more fragility, consistent with previous observations in diabetic animal models. Why high glucose levels facilitate fragility is worthy of further investigation.
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Affiliation(s)
- Qinghua Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China; Department of Pharmaceutical Analysis, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Zuobin Zhu
- Department of Genetics, School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Mengmeng Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China; Department of Pharmaceutical Analysis, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Yuechen Wang
- Department of Genetics, School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Peng Zhang
- School of Electronic Information and Engineering, Yangtze Normal University, Chongqing, 408003, China
| | - Hao Wang
- School of The First Clinical Medicine, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Mengyu Liang
- School of The First Clinical Medicine, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Ying Li
- Department of Clinical Microbiology, School of Medical Laboratory, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Bin Deng
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Daoquan Tang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China; Department of Pharmaceutical Analysis, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China
| | - Robert G Gilbert
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia; Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland, 4072, Australia; Joint International Research Laboratory of Agriculture and Agri-Product Safety, College of Agriculture, Yangzhou University, Yangzhou, 225009, Jiangsu, China.
| | - Liang Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China; Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, Jiangsu, 221000, China.
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17
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Some molecular structural features of glycogen in the kidneys of diabetic rats. Carbohydr Polym 2019; 229:115526. [PMID: 31826402 DOI: 10.1016/j.carbpol.2019.115526] [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: 08/01/2019] [Revised: 10/09/2019] [Accepted: 10/22/2019] [Indexed: 12/27/2022]
Abstract
Glycogen, a highly-branched glucose polymer, functions as a sugar reservoir in many organs and tissues. Liver glycogen comprises small β particles which can bind to form into large agglomerates (α particles) which readily degrade to β particles in diabetic livers. Muscle glycogen has only β particles, optimal for quick energy release. Healthy kidney contains negligible glycogen, but there is an abnormally high accumulation in diabetic kidneys. We here compare the molecular structure of glycogen in diabetic kidneys with that in liver and muscle, using a diabetic rat model. This involved exploring extraction techniques to minimize glycogen degradation. Using size exclusion chromatography and transmission electron microscopy, it was found that there were only β particles in diabetic kidneys. These are postulated to form during periods of abnormally high blood sugar, the driving force being the need to reduce blood sugar under such circumstances.
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18
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Brewer MK, Gentry MS. Brain Glycogen Structure and Its Associated Proteins: Past, Present and Future. ADVANCES IN NEUROBIOLOGY 2019; 23:17-81. [PMID: 31667805 PMCID: PMC7239500 DOI: 10.1007/978-3-030-27480-1_2] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This chapter reviews the history of glycogen-related research and discusses in detail the structure, regulation, chemical properties and subcellular distribution of glycogen and its associated proteins, with particular focus on these aspects in brain tissue.
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Affiliation(s)
- M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Center, Lafora Epilepsy Cure Initiative, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Center, Lafora Epilepsy Cure Initiative, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, USA.
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19
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Big data can cause big mistakes: using the Societas Europaea Herpetologica atlas by Sillero et al. (2014), the distribution of Emys orbicularis will be misunderstood. Biologia (Bratisl) 2018. [DOI: 10.1007/bf00341563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Abstract
Glycogen, the primary storage form of glucose, is a rapid and accessible form of energy that can be supplied to tissues on demand. Each glycogen granule, or "glycosome," is considered an independent metabolic unit composed of a highly branched polysaccharide and various proteins involved in its metabolism. In this Minireview, we review the literature to follow the dynamic life of a glycogen granule in a multicompartmentalized system, i.e. the cell, and how and where glycogen granules appear and the factors governing its degradation. A better understanding of the importance of cellular compartmentalization as a regulator of glycogen metabolism is needed to unravel its role in brain energetics.
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Affiliation(s)
- Clara Prats
- Center for Healthy Aging, Copenhagen 2200, Denmark; Core Facility for Integrated Microscopy, Department of Biomedical Sciences, University of Copenhagen, Copenhagen 2200, Denmark.
| | - Terry E Graham
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Jane Shearer
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Calgary, Alberta T2N 1N4, Canada; Faculty of Kinesiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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21
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Hu Z, Deng B, Tan X, Gan H, Li C, Nada SS, Sullivan MA, Li J, Jiang X, Li E, Gilbert RG. Diurnal changes of glycogen molecular structure in healthy and diabetic mice. Carbohydr Polym 2018; 185:145-152. [PMID: 29421051 DOI: 10.1016/j.carbpol.2018.01.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 12/20/2017] [Accepted: 01/01/2018] [Indexed: 12/28/2022]
Abstract
Glycogen is a complex branched glucose polymer functioning as a blood-sugar reservoir in animals. Liver glycogen β particles can bind together to form α particles, which have a slower enzymatic degradation to glucose. The linkage between β particles in α particles in diabetic liver breaks (is fragile) in dimethyl sulfoxide (DMSO), a H-bond disruptor, consistent with blood-sugar homeostasis loss in diabetes. We examined diurnal changes in the molecular structure of healthy and diabetic mouse-liver glycogen. Healthy mouse glycogen was fragile to DMSO during glycogen synthesis but not degradation; diabetic glycogen was always fragile. Two alternative mechanisms for this are suggested: healthy glycogen is fragile when formed and becomes stable during subsequent degradation, a process damaged in diabetes; alternatively, there are two types of glycogen: one compact but fragile and the other loose but non-fragile. This suggests potential types of diabetes drug targets through modifying the activities of glycogen synthesis enzymes.
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Affiliation(s)
- Zhenxia Hu
- Department of Pharmacy, Renmin Hospital of Wuhan University, Wuhan, Hubei 430030, China
| | - Bin Deng
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| | - Xinle Tan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, 4072, Australia
| | - Hua Gan
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Cheng Li
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, College of Agriculture, Yangzhou University, Yangzhou 225009, Jiangsu Province, China
| | - Sharif S Nada
- The University of Queensland, Centre for Nutrition and Food Science, Queensland Alliance for Agriculture and Food Innovation, Brisbane, QLD 4072, Australia
| | - Mitchell A Sullivan
- Glycation and Diabetes, Mater Research Institute, Translational Research Institute, The University of Queensland, Brisbane, QLD 4102, Australia
| | - Jialun Li
- Department of Plastic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Xiaoyin Jiang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Enpeng Li
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, College of Agriculture, Yangzhou University, Yangzhou 225009, Jiangsu Province, China
| | - Robert G Gilbert
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, College of Agriculture, Yangzhou University, Yangzhou 225009, Jiangsu Province, China; School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; The University of Queensland, Centre for Nutrition and Food Science, Queensland Alliance for Agriculture and Food Innovation, Brisbane, QLD 4072, Australia
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22
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Hu Z, Tan X, Deng B, Gan H, Jiang X, Wang K, Li C, Li E, Gilbert RG, Sullivan MA. Implications for biological function of lobe dependence of the molecular structure of liver glycogen. Eur Polym J 2017. [DOI: 10.1016/j.eurpolymj.2017.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Deng B, Sullivan MA, Chen C, Li J, Powell PO, Hu Z, Gilbert RG. Molecular Structure of Human-Liver Glycogen. PLoS One 2016; 11:e0150540. [PMID: 26934359 PMCID: PMC4775040 DOI: 10.1371/journal.pone.0150540] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/15/2016] [Indexed: 01/08/2023] Open
Abstract
Glycogen is a highly branched glucose polymer which is involved in maintaining blood-sugar homeostasis. Liver glycogen contains large composite α particles made up of linked β particles. Previous studies have shown that the binding which links β particles into α particles is impaired in diabetic mice. The present study reports the first molecular structural characterization of human-liver glycogen from non-diabetic patients, using transmission electron microscopy for morphology and size-exclusion chromatography for the molecular size distribution; the latter is also studied as a function of time during acid hydrolysis in vitro, which is sensitive to certain structural features, particularly glycosidic vs. proteinaceous linkages. The results are compared with those seen in mice and pigs. The molecular structural change during acid hydrolysis is similar in each case, and indicates that the linkage of β into α particles is not glycosidic. This result, and the similar morphology in each case, together imply that human liver glycogen has similar molecular structure to those of mice and pigs. This knowledge will be useful for future diabetes drug targets.
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Affiliation(s)
- Bin Deng
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Mitchell A. Sullivan
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
- Centre for Nutrition and Food Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, 4072, Australia
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada
| | - Cheng Chen
- Department of Endocrinology, Wuhan General Hospital of Guangzhou Military Command, Wuluo Road 627, Wuhan, Hubei, 430070, China
| | - Jialun Li
- Department of Plastic Surgery, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Prudence O. Powell
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
- Centre for Nutrition and Food Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Zhenxia Hu
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Robert G. Gilbert
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
- Centre for Nutrition and Food Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, 4072, Australia
- * E-mail:
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Liver glycogen in type 2 diabetic mice is randomly branched as enlarged aggregates with blunted glucose release. Glycoconj J 2015; 33:41-51. [PMID: 26521055 DOI: 10.1007/s10719-015-9631-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 12/28/2022]
Abstract
Glycogen is a vital highly branched polymer of glucose that is essential for blood glucose homeostasis. In this article, the structure of liver glycogen from mice is investigated with respect to size distributions, degradation kinetics, and branching structure, complemented by a comparison of normal and diabetic liver glycogen. This is done to screen for differences that may result from disease. Glycogen α-particle (diameter ∼ 150 nm) and β-particle (diameter ∼ 25 nm) size distributions are reported, along with in vitro γ-amylase degradation experiments, and a small angle X-ray scattering analysis of mouse β-particles. Type 2 diabetic liver glycogen upon extraction was found to be present as large loosely bound, aggregates, not present in normal livers. Liver glycogen was found to aggregate in vitro over a period of 20 h, and particle size is shown to be related to rate of glucose release, allowing a structure-function relationship to be inferred for the tissue specific distribution of particle types. Application of branching theories to small angle X-ray scattering data for mouse β-particles revealed these particles to be randomly branched polymers, not fractal polymers. Together, this article shows that type 2 diabetic liver glycogen is present as large aggregates in mice, which may contribute to the inflexibility of interconversion between glucose and glycogen in type 2 diabetes, and further that glycogen particles are randomly branched with a size that is related to the rate of glucose release.
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26
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Chandramouli C, Varma U, Stevens EM, Xiao RP, Stapleton DI, Mellor KM, Delbridge LMD. Myocardial glycogen dynamics: New perspectives on disease mechanisms. Clin Exp Pharmacol Physiol 2015; 42:415-25. [DOI: 10.1111/1440-1681.12370] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 12/29/2014] [Accepted: 01/06/2015] [Indexed: 11/26/2022]
Affiliation(s)
| | - Upasna Varma
- Department of Physiology; University of Melbourne; Melbourne Vic. Australia
| | - Ellie M Stevens
- Department of Physiology; University of Auckland; Auckland New Zealand
| | - Rui-Ping Xiao
- Institute of Molecular Medicine; Peking University; Beijing China
| | - David I Stapleton
- Department of Physiology; University of Melbourne; Melbourne Vic. Australia
- The Florey Institute of Neuroscience; Melbourne Vic. Australia
| | - Kimberley M Mellor
- Department of Physiology; University of Melbourne; Melbourne Vic. Australia
- Department of Physiology; University of Auckland; Auckland New Zealand
| | - Lea MD Delbridge
- Department of Physiology; University of Melbourne; Melbourne Vic. Australia
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27
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Sullivan MA, Powell PO, Witt T, Vilaplana F, Roura E, Gilbert RG. Improving size-exclusion chromatography separation for glycogen. J Chromatogr A 2014; 1332:21-9. [PMID: 24508396 DOI: 10.1016/j.chroma.2014.01.053] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 12/23/2013] [Accepted: 01/20/2014] [Indexed: 10/25/2022]
Abstract
Glycogen is a hyperbranched glucose polymer comprised of glycogen β particles, which can also form much larger composite α particles. The recent discovery using size-exclusion chromatography (SEC) that fewer, smaller, α particles are found in diabetic-mouse liver compared to healthy mice highlights the need to achieve greater accuracy in the size separation methods used to analyze α and β particles. While past studies have used dimethyl sulfoxide as the SEC eluent to analyze the molecular size and structure of native glycogen, an aqueous eluent has not been rigorously tested and compared with dimethyl sulfoxide. The conditions for SEC of pig-liver glycogen, phytoglycogen and oyster glycogen were optimized by comparing two different eluents, aqueous 50 mM NH₄NO₃/0.02% NaN₃ and dimethyl sulfoxide/0.5% LiBr, run through different column materials and pore sizes at various flow rates. The aqueous system gave distinct size separation of α- and β-particle peaks, allowing for a more detailed and quantitative analysis and comparison between liver glycogen samples. This greater resolution has also revealed key differences between the structure of liver glycogen and phytoglycogen.
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Affiliation(s)
- Mitchell A Sullivan
- Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, Queensland 4072, Australia
| | - Prudence O Powell
- Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, Queensland 4072, Australia
| | - Torsten Witt
- Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, Queensland 4072, Australia
| | - Francisco Vilaplana
- The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, Queensland 4072, Australia; Division of Glycoscience, School of Biotechnology and Wallenberg Wood Science Centre (WWSC), KTH Royal Institute of Technology, AlbaNova University Centre, SE-106 91 Stockholm, Sweden
| | - Eugeni Roura
- The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, Queensland 4072, Australia
| | - Robert G Gilbert
- Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, Queensland 4072, Australia.
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Sullivan MA, Aroney STN, Li S, Warren FJ, Joo JS, Mak KS, Stapleton DI, Bell-Anderson KS, Gilbert RG. Changes in glycogen structure over feeding cycle sheds new light on blood-glucose control. Biomacromolecules 2014; 15:660-5. [PMID: 24372590 DOI: 10.1021/bm401714v] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Liver glycogen, a highly branched polymer of glucose, is important for maintaining blood-glucose homeostasis. It was recently shown that db/db mice, a model for Type 2 diabetes, are unable to form the large composite glycogen α particles present in normal, healthy mice. In this study, the structure of healthy mouse-liver glycogen over the diurnal cycle was characterized using size exclusion chromatography and transmission electron microscopy. Glycogen was found to be formed as smaller β particles, and then only assembled into large α particles, with a broad size distribution, significantly after the time when glycogen content had reached a maximum. This pathway, missing in diabetic animals, is likely to give optimal blood-glucose control during the daily feeding cycle. Lack of this control may contribute to, or result from, diabetes. This discovery suggests novel approaches to diabetes management.
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Affiliation(s)
- Mitchell A Sullivan
- Tongji School of Pharmacy, Huazhong University of Science and Technology , Wuhan, Hubei 430030, China
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Gilbert RG, Sullivan MA. The Molecular Size Distribution of Glycogen and its Relevance to Diabetes. Aust J Chem 2014. [DOI: 10.1071/ch13573] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Glycogen is a highly branched polymer of glucose, functioning as a blood-glucose buffer. It comprises relatively small β-particles, which may be joined as larger aggregate α-particles. The size distributions from size-exclusion chromatography (SEC, also known as GPC) of liver glycogen from non-diabetic and diabetic mice show that diabetic mice have impaired α-particle formation, shedding new light on diabetes. SEC data also suggest the type of bonding holding β-particles together in α-particles. SEC characterisation of liver glycogen at various time points in a day/night cycle indicates that liver glycogen is initially synthesised as β-particles, and then joined by an unknown process to form α-particles. These α-particles are more resistant to degradation, presumably because of their lower surface area-to-volume ratio. These findings have important implications for new drug targets for diabetes management.
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Timmes AG, Moore RA, Fischer ER, Priola SA. Recombinant prion protein refolded with lipid and RNA has the biochemical hallmarks of a prion but lacks in vivo infectivity. PLoS One 2013; 8:e71081. [PMID: 23936256 PMCID: PMC3728029 DOI: 10.1371/journal.pone.0071081] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 06/24/2013] [Indexed: 11/21/2022] Open
Abstract
During prion infection, the normal, protease-sensitive conformation of prion protein (PrPC) is converted via seeded polymerization to an abnormal, infectious conformation with greatly increased protease-resistance (PrPSc). In vitro, protein misfolding cyclic amplification (PMCA) uses PrPSc in prion-infected brain homogenates as an initiating seed to convert PrPC and trigger the self-propagation of PrPSc over many cycles of amplification. While PMCA reactions produce high levels of protease-resistant PrP, the infectious titer is often lower than that of brain-derived PrPSc. More recently, PMCA techniques using bacterially derived recombinant PrP (rPrP) in the presence of lipid and RNA but in the absence of any starting PrPSc seed have been used to generate infectious prions that cause disease in wild-type mice with relatively short incubation times. These data suggest that lipid and/or RNA act as cofactors to facilitate the de novo formation of high levels of prion infectivity. Using rPrP purified by two different techniques, we generated a self-propagating protease-resistant rPrP molecule that, regardless of the amount of RNA and lipid used, had a molecular mass, protease resistance and insolubility similar to that of PrPSc. However, we were unable to detect prion infectivity in any of our reactions using either cell-culture or animal bioassays. These results demonstrate that the ability to self-propagate into a protease-resistant insoluble conformer is not unique to infectious PrP molecules. They suggest that the presence of RNA and lipid cofactors may facilitate the spontaneous refolding of PrP into an infectious form while also allowing the de novo formation of self-propagating, but non-infectious, rPrP-res.
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Affiliation(s)
- Andrew G. Timmes
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, Montana, United States of America
| | - Roger A. Moore
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, Montana, United States of America
| | - Elizabeth R. Fischer
- Electron Microscopy Unit, Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, Montana, United States of America
| | - Suzette A. Priola
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, Montana, United States of America
- * E-mail:
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Gilbert RG, Wu AC, Sullivan MA, Sumarriva GE, Ersch N, Hasjim J. Improving human health through understanding the complex structure of glucose polymers. Anal Bioanal Chem 2013; 405:8969-80. [DOI: 10.1007/s00216-013-7129-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 06/01/2013] [Accepted: 06/06/2013] [Indexed: 10/26/2022]
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Sullivan MA, O'Connor MJ, Umana F, Roura E, Jack K, Stapleton DI, Gilbert RG. Molecular insights into glycogen α-particle formation. Biomacromolecules 2012; 13:3805-13. [PMID: 23004915 DOI: 10.1021/bm3012727] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glycogen, a hyperbranched complex glucose polymer, is an intracellular glucose store that provides energy for cellular functions, with liver glycogen involved in blood-glucose regulation. Liver glycogen comprises complex α particles made up of smaller β particles. The recent discovery that these α particles are smaller and fewer in diabetic, compared with healthy, mice highlights the need to elucidate the nature of α-particle formation; this paper tests various possibilities for binding within α particles. Acid hydrolysis effects, examined using dynamic light scattering and size exclusion chromatography, showed that the binding is not simple α-(1→4) or α-(1→6) glycosidic linkages. There was no significant change in α particle size after the addition of various reagents, which disrupt disulfide, protein, and hydrogen bonds and hydrophobic interactions. The results are consistent with proteinaceous binding between β particles in α particles, with the inability of protease to break apart particles being attributed to steric hindrance.
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Affiliation(s)
- Mitchell A Sullivan
- Centre for Nutrition & Food Sciences (Building 83/S434), Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Qld 4072, Australia
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Besford QA, Sullivan MA, Zheng L, Gilbert RG, Stapleton D, Gray-Weale A. The structure of cardiac glycogen in healthy mice. Int J Biol Macromol 2012; 51:887-91. [PMID: 22782068 DOI: 10.1016/j.ijbiomac.2012.06.037] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 05/06/2012] [Accepted: 06/26/2012] [Indexed: 12/12/2022]
Abstract
Transmission electron micrographs of glycogen extracted from healthy mouse hearts reveal aggregate structures around 133 nm in diameter. These structures are similar to, but on average somewhat smaller than, the α-particles of glycogen found in mammalian liver. Like the larger liver glycogens, these new particles in cardiac tissue appear to be aggregates of β-particles. Free β-particles are also present in liver, and are the only type of particle seen in skeletal muscle. They have diameters from 20 to 50 nm. We discuss the number distributions of glycogen particle diameters and the implications for the structure-function relationship of glycogens in these tissues. We point out the possible implications for the study of glycogen storage diseases, and of non-insulin dependent diabetes mellitus.
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Affiliation(s)
- Quinn A Besford
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
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Abstract
Glycogen is a branched polymer of glucose that acts as a store of energy in times of nutritional sufficiency for utilization in times of need. Its metabolism has been the subject of extensive investigation and much is known about its regulation by hormones such as insulin, glucagon and adrenaline (epinephrine). There has been debate over the relative importance of allosteric compared with covalent control of the key biosynthetic enzyme, glycogen synthase, as well as the relative importance of glucose entry into cells compared with glycogen synthase regulation in determining glycogen accumulation. Significant new developments in eukaryotic glycogen metabolism over the last decade or so include: (i) three-dimensional structures of the biosynthetic enzymes glycogenin and glycogen synthase, with associated implications for mechanism and control; (ii) analyses of several genetically engineered mice with altered glycogen metabolism that shed light on the mechanism of control; (iii) greater appreciation of the spatial aspects of glycogen metabolism, including more focus on the lysosomal degradation of glycogen; and (iv) glycogen phosphorylation and advances in the study of Lafora disease, which is emerging as a glycogen storage disease.
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Montori-Grau M, Guitart M, García-Martínez C, Orozco A, Gómez-Foix AM. Differential pattern of glycogen accumulation after protein phosphatase 1 glycogen-targeting subunit PPP1R6 overexpression, compared to PPP1R3C and PPP1R3A, in skeletal muscle cells. BMC BIOCHEMISTRY 2011; 12:57. [PMID: 22054094 PMCID: PMC3240831 DOI: 10.1186/1471-2091-12-57] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 11/04/2011] [Indexed: 01/17/2023]
Abstract
BACKGROUND PPP1R6 is a protein phosphatase 1 glycogen-targeting subunit (PP1-GTS) abundant in skeletal muscle with an undefined metabolic control role. Here PPP1R6 effects on myotube glycogen metabolism, particle size and subcellular distribution are examined and compared with PPP1R3C/PTG and PPP1R3A/G(M). RESULTS PPP1R6 overexpression activates glycogen synthase (GS), reduces its phosphorylation at Ser-641/0 and increases the extracted and cytochemically-stained glycogen content, less than PTG but more than G(M). PPP1R6 does not change glycogen phosphorylase activity. All tested PP1-GTS-cells have more glycogen particles than controls as found by electron microscopy of myotube sections. Glycogen particle size is distributed for all cell-types in a continuous range, but PPP1R6 forms smaller particles (mean diameter 14.4 nm) than PTG (36.9 nm) and G(M) (28.3 nm) or those in control cells (29.2 nm). Both PPP1R6- and G(M)-derived glycogen particles are in cytosol associated with cellular structures; PTG-derived glycogen is found in membrane- and organelle-devoid cytosolic glycogen-rich areas; and glycogen particles are dispersed in the cytosol in control cells. A tagged PPP1R6 protein at the C-terminus with EGFP shows a diffuse cytosol pattern in glucose-replete and -depleted cells and a punctuate pattern surrounding the nucleus in glucose-depleted cells, which colocates with RFP tagged with the Golgi targeting domain of β-1,4-galactosyltransferase, according to a computational prediction for PPP1R6 Golgi location. CONCLUSIONS PPP1R6 exerts a powerful glycogenic effect in cultured muscle cells, more than G(M) and less than PTG. PPP1R6 protein translocates from a Golgi to cytosolic location in response to glucose. The molecular size and subcellular location of myotube glycogen particles is determined by the PPP1R6, PTG and G(M) scaffolding.
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Affiliation(s)
- Marta Montori-Grau
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain.
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36
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37
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Gilbert RG. Size-separation characterization of starch and glycogen for biosynthesis-structure-property relationships. Anal Bioanal Chem 2010; 399:1425-38. [PMID: 21107973 DOI: 10.1007/s00216-010-4435-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Revised: 11/07/2010] [Accepted: 11/09/2010] [Indexed: 10/18/2022]
Abstract
Starch and glycogen are highly branched polymers of glucose of great importance to humans in managing and mitigating nutrition-related diseases, especially diabetes and obesity, and in industrial uses, for example in food and paper-making. Size-separation characterization using multiple-detection size-exclusion chromatography (SEC, also known as gel-permeation chromatography, GPC) is able to furnish substantial amounts of information on the relationships between the biosynthesis, processing, structure, and properties of these biopolymers, and achieves superior characterization for use in industrial product and process improvements. Multi-detector SEC is able to give much more information about structure than simple averages such as total molecular weight or size; the detailed information yielded by this technique has already given new information on important biosynthesis-structure-property reactions, and has considerable potential in this field in the future. However, it must be used with care to avoid artifacts arising from incomplete dissolution of the substrate and shear scission during separation. It is also essential in interpreting data to appreciate that this size-separation technique can only ever give size distributions, never true molecular weight distributions. Other size-separation techniques, particularly field-flow fractionation, require substantial technical development to be used on undegraded native starches.
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Affiliation(s)
- Robert G Gilbert
- Centre for Nutrition & Food Sciences (LCAFS), The University of Queensland, Brisbane, Qld 4072, Australia.
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Sullivan MA, Vilaplana F, Cave RA, Stapleton D, Gray-Weale AA, Gilbert RG. Nature of alpha and beta particles in glycogen using molecular size distributions. Biomacromolecules 2010; 11:1094-100. [PMID: 20196533 DOI: 10.1021/bm100074p] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glycogen is a randomly hyperbranched glucose polymer. Complex branched polymers have two structural levels: individual branches and the way these branches are linked. Liver glycogen has a third level: supramolecular clusters of beta particles which form larger clusters of alpha particles. Size distributions of native glycogen were characterized using size exclusion chromatography (SEC) to find the number and weight distributions and the size dependences of the number- and weight-average masses. These were fitted to two distinct randomly joined reference structures, constructed by random attachment of individual branches and as random aggregates of beta particles. The z-average size of the alpha particles in dimethylsulfoxide does not change significantly with high concentrations of LiBr, a solvent system that would disrupt hydrogen bonding. These data reveal that the beta particles are covalently bonded to form alpha particles through a hitherto unsuspected enzyme process, operative in the liver on particles above a certain size range.
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Affiliation(s)
- Mitchell A Sullivan
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
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39
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Ryu JH, Drain J, Kim JH, McGee S, Gray-Weale A, Waddington L, Parker GJ, Hargreaves M, Yoo SH, Stapleton D. Comparative structural analyses of purified glycogen particles from rat liver, human skeletal muscle and commercial preparations. Int J Biol Macromol 2009; 45:478-82. [DOI: 10.1016/j.ijbiomac.2009.08.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 08/19/2009] [Accepted: 08/20/2009] [Indexed: 10/20/2022]
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40
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Tagliabracci VS, Girard JM, Segvich D, Meyer C, Turnbull J, Zhao X, Minassian BA, Depaoli-Roach AA, Roach PJ. Abnormal metabolism of glycogen phosphate as a cause for Lafora disease. J Biol Chem 2008; 283:33816-25. [PMID: 18852261 PMCID: PMC2590708 DOI: 10.1074/jbc.m807428200] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 10/09/2008] [Indexed: 12/25/2022] Open
Abstract
Lafora disease is a progressive myoclonus epilepsy with onset in the teenage years followed by neurodegeneration and death within 10 years. A characteristic is the widespread formation of poorly branched, insoluble glycogen-like polymers (polyglucosan) known as Lafora bodies, which accumulate in neurons, muscle, liver, and other tissues. Approximately half of the cases of Lafora disease result from mutations in the EPM2A gene, which encodes laforin, a member of the dual specificity protein phosphatase family that is able to release the small amount of covalent phosphate normally present in glycogen. In studies of Epm2a(-/-) mice that lack laforin, we observed a progressive change in the properties and structure of glycogen that paralleled the formation of Lafora bodies. At three months, glycogen metabolism remained essentially normal, even though the phosphorylation of glycogen has increased 4-fold and causes altered physical properties of the polysaccharide. By 9 months, the glycogen has overaccumulated by 3-fold, has become somewhat more phosphorylated, but, more notably, is now poorly branched, is insoluble in water, and has acquired an abnormal morphology visible by electron microscopy. These glycogen molecules have a tendency to aggregate and can be recovered in the pellet after low speed centrifugation of tissue extracts. The aggregation requires the phosphorylation of glycogen. The aggregrated glycogen sequesters glycogen synthase but not other glycogen metabolizing enzymes. We propose that laforin functions to suppress excessive glycogen phosphorylation and is an essential component of the metabolism of normally structured glycogen.
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Affiliation(s)
- Vincent S Tagliabracci
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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41
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Parker GJ, Koay A, Gilbert-Wilson R, Waddington LJ, Stapleton D. AMP-activated protein kinase does not associate with glycogen alpha-particles from rat liver. Biochem Biophys Res Commun 2007; 362:811-5. [PMID: 17767922 DOI: 10.1016/j.bbrc.2007.08.080] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/07/2007] [Indexed: 11/28/2022]
Abstract
The AMP-activated protein kinase (AMPK) is heterotrimer consisting of alpha catalytic subunit and beta/gamma regulatory subunits. It acts as a critical focal point for whole body and cellular mechanisms maintaining energy homeostasis by regulating carbohydrate and lipid metabolism, food intake, gene transcription, and protein synthesis. The AMPK beta subunit contains a glycogen-binding domain that has been shown to associate with glycogen particles in vitro and glycogen phosphorylase and glycogen synthase in cultured cells. To determine whether AMPK associates with glycogen particles in vivo, we developed a procedure to purify glycogen alpha-particles to apparent homogeneity from rat liver. Using immunoreactivity and mass spectrometry we determined that AMPK does not associate with the glycogen particle in livers from random-fed rats. This surprising finding indicates that the glycogen-binding properties of the AMPK beta subunit are likely regulated and responsive to the metabolic status of the hepatocyte.
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Affiliation(s)
- Glendon J Parker
- Department of Medicine, Rm 4C464B SOM, 30 N 1900 E, 84132, School of Medicine, University of Utah, Salt Lake City, UT, USA
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42
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Konkolewicz D, Gilbert RG, Gray-Weale A. Randomly hyperbranched polymers. PHYSICAL REVIEW LETTERS 2007; 98:238301. [PMID: 17677941 DOI: 10.1103/physrevlett.98.238301] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Indexed: 05/16/2023]
Abstract
We describe a model for the structures of randomly hyperbranched polymers in solution, and find a logarithmic growth of radius with polymer mass. We include segmental overcrowding, which puts an upper limit on the density. The model is tested against simulations, against data on amylopectin, a major component of starch, on glycogen, and on polyglycerols. For samples of synthetic polyglycerol and glycogen, our model holds well for all the available data. The model reveals higher-level scaling structure in glycogen, related to the beta particles seen in electron microscopy.
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43
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Larner J. Insulin and the stimulation of glycogen synthesis. The road from glycogen structure to glycogen synthase to cyclic AMP-dependent protein kinase to insulin mediators. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 63:173-231. [PMID: 2154910 DOI: 10.1002/9780470123096.ch3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The enhanced phosphorylations via cAMP, Ca2+ mobilization, and diacyl glycerol formation via the activation of the respective kinases is now classical. The decreased phosphorylation via inhibition of adenylate cyclase via the alpha adrenergic receptor is also becoming understood. What the insulin studies on the control of glycogen synthesis have taught us is that the rate limiting enzyme glycogen synthase is regulated by multiple covalent phosphorylation in an elegant but complex manner. The overall pattern of dephosphorylation is influenced by effecting both phosphatase and kinase activities in a set of interrelated mechanisms. In the presence of glucose, in muscle, fat, and liver under physiological conditions G-6-P acts as a signal to stimulate the phosphatase. An additional stimulation could occur via a novel insulin phosphatase stimulatory mediator. The phosphatase is also stimulated by at least three covalent mechanisms involving altered phosphorylation state. In one there is a decreased phosphorylation of the phosphatase inhibitor 1 potentially related to decreased cAMP-dependent protein kinase activity. In the second, there is decreased phosphorylation of the deinhibitor also potentially related to decreased cAMP-dependent protein kinase phosphorylation. In the third, an increased activity of casein kinase 2 could activate the ATP-Mg dependent phosphatase by an increased phosphorylation of phosphatase inhibitor 2 (modulatory subunit). In the liver, allosteric control of the phosphatase by G-6-P and nucleotides is of great importance. Insulin also stimulates the phosphatase in long-term experiments via increased protein synthesis. It is clear that future work will be required to determine which species of the various classes of phosphatases are regulated in short-term and long-term regulation by insulin. In terms of kinases, the effects of insulin to inactivate and desensitize the cAMP-dependent protein kinase are established. The molecular mechanisms of this effect remain to be worked out. The enhanced activity of MAP and S-6 kinase would appear to be part of a cascade of reactions perhaps originating in the autophosphorylation and activation of the insulin receptor tyrosine kinase. The mechanism of the short-term activation of casein kinase 2 remains to be elucidated. A cAMP-dependent protein kinase inhibitory mediator, which also inhibits adenylate cyclase is an important element in the regulation of kinase and adenylate cyclase activity by insulin. Its physiological significance must be established in the future, in terms of its control of glycogen synthase activation by insulin. Clearly this kinase inhibitor as well as the phosphatase stimulator are potential regulators of glycogen synthase activity by insulin.
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Affiliation(s)
- J Larner
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908
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44
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Putaux JL, Potocki-Véronèse G, Remaud-Simeon M, Buleon A. Alpha-D-glucan-based dendritic nanoparticles prepared by in vitro enzymatic chain extension of glycogen. Biomacromolecules 2006; 7:1720-8. [PMID: 16768390 DOI: 10.1021/bm050988v] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The recombinant amylosucrase from Neisseria polysaccharea was used to glucosylate glycogen particles in vitro in the presence of sucrose as the glucosyl donor. The morphology and structure of the resulting insoluble products were shown to strongly depend on the initial sucrose/glycogen weight ratio. For the lower ratio (1.14), all glucose molecules produced from sucrose were transferred onto glycogen, yielding a slight elongation of the external chains and their organization into small crystallites at the surface of the glycogen particles. With a high initial sucrose/glycogen ratio (342), the external glycogen chains were extended by amylosucrase, yielding dendritic nanoparticles with a diameter 4-5 times that of the initial particle. A partial crystallization of the elongated chains induced a "shrinkage" of the nanospheres. The synthesis of linear alpha-(1,4) chains occurred simultaneously, yielding semicrystalline fibrous entities. All products displayed a B-type crystal structure. The kinetics of chain elongation and aggregation were thoroughly investigated in order to explain how the action of amylosucrase resulted in such different structures. These results emphasize the potentiality of amylosucrase in the design of original carbohydrate-based dendritic nanoparticles.
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Affiliation(s)
- Jean-Luc Putaux
- Centre de Recherches sur les Macromolécules Végétales, ICMG-CNRS, BP 53, F-38041 Grenoble Cedex 9, France
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45
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Chaigneau J, Besse C, Jaros PP, Martin G, Wägele JW, Willig A. Organ of Bellonci of an Antarctic crustacean, the marine isopod Glyptonotus antarcticus. J Morphol 2005; 207:119-128. [PMID: 29865497 DOI: 10.1002/jmor.1052070202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The paired organ of Bellonci protrudes from the optic lobe of the giant Antarctic isopod, Glyptonotus antarcticus. It is linked to the cortex by a broad peduncle. No connection to the cuticle or "sensory pore organ" was found. A cluster of sensory-like cells forms two outer ciliary segments branching into numerous microvilli with microtubules. The putative sensory somata are irregular in shape and contain a very high density of glycogen granules. The two outer segments sprout from two pits of the soma in different directions, forming a right angle. Glial cells wrap around the sensory cells and also delimit lacunae into which bundles of microvilli project. These lacunae contain electron-dense granules of small size and with species-specific patterns. Lacunae and dense granules show features typical of a degeneration process in the sensory cells. This general morphology corresponds to the unilobular type of organ of Bellonci, known in other isopods; it differs from the plurilobular type with onion bodies found in other Crustacea.
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Affiliation(s)
- Jean Chaigneau
- Laboratoire de Biologie Animale de l'Université de Poitiers, F-86022 Poitiers, France.,Service Universitaire de Microscopie Electronique Biologique (S.U.M.E.B), de l'Université de Poitiers, F-86022 Poitiers, France
| | - Colette Besse
- Service Universitaire de Microscopie Electronique Biologique (S.U.M.E.B), de l'Université de Poitiers, F-86022 Poitiers, France
| | - Peter P Jaros
- Universität Oldenburg, Fachbereich Biologie, D-2900 Oldenburg, Federal Republic of Germany
| | - Gilbert Martin
- Laboratoire de Biologie Animale de l'Université de Poitiers, F-86022 Poitiers, France
| | - J Wolfgang Wägele
- Universität Oldenburg, Fachbereich Biologie, D-2900 Oldenburg, Federal Republic of Germany
| | - Axel Willig
- Universität Oldenburg, Fachbereich Biologie, D-2900 Oldenburg, Federal Republic of Germany
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46
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Marchand I, Chorneyko K, Tarnopolsky M, Hamilton S, Shearer J, Potvin J, Graham TE. Quantification of subcellular glycogen in resting human muscle: granule size, number, and location. J Appl Physiol (1985) 2002; 93:1598-607. [PMID: 12381743 DOI: 10.1152/japplphysiol.00585.2001] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A few qualitative investigations suggested that location of muscle glycogen (G) granules in specific sites may be associated with distinct metabolic roles. Similarly, it has been suggested that the acid-soluble and -insoluble G fractions (macro- and proglycogen, respectively) are different metabolic pools and also could exist as separate entities. We employed a transmission electron microscopic technique to quantify subcellular G particle size, number, and location in human vastus lateralis biopsies of 11 resting men. The intra- and interobserver variability for the various measures was generally <4%. Granule size and number were quantified in subcellular compartments (subsarcolemmal, intra- and intermyofibrillar). Subcellular location was critical: G was more densely concentrated in the subsarcolemmal than in the myofibrillar space, whereas the single-particle volume was greater in the latter. Single-particle diameter ranged from 10 to 44 etam and followed a continuous, normal distribution. This implies that proglycogen is not a distinct entity, but rather that pro- and macroglycogen are divisions of smaller and larger molecules. These results demonstrate a compartmentalized pattern of subcellular G deposition in human skeletal muscle for both the size and density of granules.
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Affiliation(s)
- I Marchand
- Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, N1G 2W1, Ontario, Canada
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47
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Abstract
In Ascaris suum, muscle glycogen is synthesized during host feeding intervals and degraded during nonfeeding intervals. Glycogen accumulation is up to 12-fold greater than that observed in mammalian muscle. Previous studies have established that many aspects of the parasite glycogen metabolism are comparable with the host, but a novel form of glycogen synthase designated GSII also occurs in the parasite. In this report glycogenin has been identified as the core protein in both mature glycogen and the GSII complex. Digestion of GSII complex glycogen generates discreet intermediates that may correspond to a proglycogen pool, whereas digestion of mature glycogen does not generate these intermediates. Because both GSII complex glycogen and mature glycogen serve as GSII substrates, the GSII complex likely represents an intermediate between glycogenin and mature glycogen. The regulation of glycogenin synthesis or the regulation of GSII activity that converts glycogenin to proglycogen, or both, may account for high levels of polysaccharide accumulation that are essential for A. suum survival.
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Affiliation(s)
- R A Masaracchia
- Department of Biological Sciences. University of North Texas, Denton 76203, USA
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48
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Hélary-Bernard K, Ardourel MY, Cloix JF, Hevor T. The xenobiotic methionine sulfoximine modulates carbohydrate anabolism and related genes expression in rodent brain. Toxicology 2000; 153:179-87. [PMID: 11090956 DOI: 10.1016/s0300-483x(00)00313-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Methionine sulfoximine is a xenobiotic amino acid derived from methionine. One of its major properties is to display a glycogenic activity in the brain. After studying this property, we investigate here a possible action of this xenobiotic on the expression of genes related to carbohydrate anabolism in the brain. Glycogen was studied by the means of electron microscopy. Astrocytes were cultured and the influence of methionine sulfoximine on carbohydrate anabolism in these cells was investigated. In vivo, methionine sulfoximine induced a large increase in glycogen accumulation. It also enhanced the glycogen accumulation in cultured astrocytes principally, when the medium was enriched in glucose. The gluconeogenic enzyme fructose-1,6-bisphosphatase may account for glycogen accumulation. Plasmids were built using antisens cDNA to permanently block the expression of fructose-1,6-bisphosphatase. An eukaryotic vector was used and the expression of fructose-1,6-bisphosphatase gene was under the control of the promoter of the glial fibrillary acidic protein. In this case, the glycogen content in cultured astrocytes largely decreased. This work shows that methionine sulfoximine enhances energy carbohydrate synthesis in the brain. Since this xenobiotic also enhances the expression of some genes related to one of the key step of glucose synthesis, it is possible that genes may be one target of methionine sulfoximine. Next investigations will study the actual effect of methionine sulfoximine in the cells.
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Affiliation(s)
- K Hélary-Bernard
- Laboratoire de Métabolisme Cérébral et Neuropathologies-E.A. 2633, Université d'Orléans, B.P. 6759, F-45067 Cedex 2, Orléans, France.
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49
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Putaux JL, Buléon A, Borsali R, Chanzy H. Ultrastructural aspects of phytoglycogen from cryo-transmission electron microscopy and quasi-elastic light scattering data. Int J Biol Macromol 1999; 26:145-50. [PMID: 10517521 DOI: 10.1016/s0141-8130(99)00076-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Phytoglycogen particles extracted from the sugary maize mutant su 1 and dispersed in water were studied using transmission electron microscopy (TEM) and light scattering. Dried specimens were either negatively stained with uranyl acetate or shadowed with W/Ta. Frozen-hydrated unstained particles embedded in a thin film of vitreous ice were also observed using cryo-TEM. The particles exhibited a spheroidal shape, with a diameter ranging from 30 to 100 nm. Some of them presented a multilobular morphology and appeared to be formed by smaller subunits, 20-30 nm in diameter, resembling the described beta-particles for animal glycogen. The diameter of stained and ice-embedded particles was measured from electron micrographs. The corresponding size distribution histograms showed that the average weight diameter of ice-embedded particles was higher than that of stained ones. In the latter case, a shrinkage of the particle was believed to occur during the drying process. Light scattering experiments confirmed the diameter of ice-embedded particles and indicated that they could be considered as uniformly dense spheroidal objects.
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Affiliation(s)
- J L Putaux
- Centre de Recherches sur les Macromolécules Végétales-CNRS, Grenoble, France.
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50
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Wary C, Desvaux H, Van Cauteren M, Vanstapel F, Carlier PG, Jehenson P. 1H NMR spectroscopy study of the dynamic properties of glycogen in solution by steady-state magnetisation measurement with off-resonance irradiation. Carbohydr Res 1998; 306:479-91. [PMID: 9679273 DOI: 10.1016/s0008-6215(98)00005-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The dynamics of size-selected fractions of glycogen in solution have been investigated by proton NMR spectroscopy, using a recently described relaxation study method which relies on strong offresonance irradiation. The dependence of the steady-state magnetisation on angle and intensity of the effective radio-frequency field was measured and compared to theoretical curves derived from different models of motion. Absence or presence of contributions to relaxation from molecular motions on the microsecond time scale can be tested with this method, without having to resort to models. We found that glycogen dipolar relaxation did not result from isotropic Brownian rotation, and despite some contribution from slow motion (> 1 microsecond) to relaxation in glycogen alpha-particles extracted from rat liver, bulk movement of the molecules did not appear to participate in averaging the dipolar term to zero. Whereas hepatic glycogen rat beta-particles and commercial oyster glycogen displayed very similar relaxation properties, alpha-particles showed significantly different behaviour. However, all results were compatible with a diversity of movements within the molecule, ranging from freely rotating pyranoside rings through collective chain motion and possibly to bulk movement of the beta sub-units within the alpha-particle.
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Affiliation(s)
- C Wary
- Service Hospitalier Frédéric Joliot, C.E.A., Orsay, France.
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