1
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Zhou N, Chen J, Ling Z, Zhang C, Zhou Y, Wang D, Zhou L, Wang Z, Sun N, Wang X, Zhang H, Tang K, Ma J, Lv J, Huang B. Aryl hydrocarbon receptor sulfenylation promotes glycogenolysis and rescues cancer chemoresistance. J Clin Invest 2023; 133:e170753. [PMID: 38099490 PMCID: PMC10721154 DOI: 10.1172/jci170753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 10/17/2023] [Indexed: 12/18/2023] Open
Abstract
Elevation of reactive oxygen species (ROS) levels is a general consequence of tumor cells' response to treatment and may cause tumor cell death. Mechanisms by which tumor cells clear fatal ROS, thereby rescuing redox balance and entering a chemoresistant state, remain unclear. Here, we show that cysteine sulfenylation by ROS confers on aryl hydrocarbon receptor (AHR) the ability to dissociate from the heat shock protein 90 complex but to bind to the PPP1R3 family member PPP1R3C of the glycogen complex in drug-treated tumor cells, thus activating glycogen phosphorylase to initiate glycogenolysis and the subsequent pentose phosphate pathway, leading to NADPH production for ROS clearance and chemoresistance formation. We found that basic ROS levels were higher in chemoresistant cells than in chemosensitive cells, guaranteeing the rapid induction of AHR sulfenylation for the clearance of excess ROS. These findings reveal that AHR can act as an ROS sensor to mediate chemoresistance, thus providing a potential strategy to reverse chemoresistance in patients with cancer.
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Affiliation(s)
- Nannan Zhou
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Jie Chen
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Zheng Ling
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Chaoqi Zhang
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
- Department of Thoracic Surgery, National Cancer Center/Cancer Hospital; and
| | - Yabo Zhou
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Dianheng Wang
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Li Zhou
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Zhenfeng Wang
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Nan Sun
- Department of Thoracic Surgery, National Cancer Center/Cancer Hospital; and
| | - Xin Wang
- Department of Breast Surgical Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College, Beijing, China
| | | | - Ke Tang
- Department of Biochemistry and Molecular Biology, and
| | - Jingwei Ma
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiadi Lv
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
| | - Bo Huang
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences
- Department of Pathology
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2
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Detering NT, Schüning T, Hensel N, Claus P. The phospho-landscape of the survival of motoneuron protein (SMN) protein: relevance for spinal muscular atrophy (SMA). Cell Mol Life Sci 2022; 79:497. [PMID: 36006469 PMCID: PMC11071818 DOI: 10.1007/s00018-022-04522-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 07/27/2022] [Accepted: 08/09/2022] [Indexed: 11/03/2022]
Abstract
Spinal muscular atrophy (SMA) is caused by low levels of the survival of motoneuron (SMN) Protein leading to preferential degeneration of lower motoneurons in the ventral horn of the spinal cord and brain stem. However, the SMN protein is ubiquitously expressed and there is growing evidence of a multisystem phenotype in SMA. Since a loss of SMN function is critical, it is important to decipher the regulatory mechanisms of SMN function starting on the level of the SMN protein itself. Posttranslational modifications (PTMs) of proteins regulate multiple functions and processes, including activity, cellular trafficking, and stability. Several PTM sites have been identified within the SMN sequence. Here, we map the identified SMN PTMs highlighting phosphorylation as a key regulator affecting localization, stability and functions of SMN. Furthermore, we propose SMN phosphorylation as a crucial factor for intracellular interaction and cellular distribution of SMN. We outline the relevance of phosphorylation of the spinal muscular atrophy (SMA) gene product SMN with regard to basic housekeeping functions of SMN impaired in this neurodegenerative disease. Finally, we compare SMA patient mutations with putative and verified phosphorylation sites. Thus, we emphasize the importance of phosphorylation as a cellular modulator in a clinical perspective as a potential additional target for combinatorial SMA treatment strategies.
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Affiliation(s)
- Nora Tula Detering
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Tobias Schüning
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Niko Hensel
- Ottawa Hospital Research Institute (OHRI), Ottawa, Canada
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Peter Claus
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany.
- Center for Systems Neuroscience (ZSN), Hannover, Germany.
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3
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Nitschke S, Sullivan MA, Mitra S, Marchioni C, Lee JP Y, Smith BH, Ahonen S, Wu J, Chown E, Wang P, Petković S, Zhao X, DiGiovanni LF, Perri AM, Israelian L, Grossman TR, Kordasiewicz H, Vilaplana F, Iwai K, Nitschke F, Minassian BA. Glycogen synthase downregulation rescues the amylopectinosis of murine RBCK1 deficiency. Brain 2022; 145:2361-2377. [PMID: 35084461 PMCID: PMC9612801 DOI: 10.1093/brain/awac017] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/17/2021] [Accepted: 01/09/2022] [Indexed: 12/06/2023] Open
Abstract
Longer glucan chains tend to precipitate. Glycogen, by far the largest mammalian glucan and the largest molecule in the cytosol with up to 55 000 glucoses, does not, due to a highly regularly branched spherical structure that allows it to be perfused with cytosol. Aberrant construction of glycogen leads it to precipitate, accumulate into polyglucosan bodies that resemble plant starch amylopectin and cause disease. This pathology, amylopectinosis, is caused by mutations in a series of single genes whose functions are under active study toward understanding the mechanisms of proper glycogen construction. Concurrently, we are characterizing the physicochemical particularities of glycogen and polyglucosans associated with each gene. These genes include GBE1, EPM2A and EPM2B, which respectively encode the glycogen branching enzyme, the glycogen phosphatase laforin and the laforin-interacting E3 ubiquitin ligase malin, for which an unequivocal function is not yet known. Mutations in GBE1 cause a motor neuron disease (adult polyglucosan body disease), and mutations in EPM2A or EPM2B a fatal progressive myoclonus epilepsy (Lafora disease). RBCK1 deficiency causes an amylopectinosis with fatal skeletal and cardiac myopathy (polyglucosan body myopathy 1, OMIM# 615895). RBCK1 is a component of the linear ubiquitin chain assembly complex, with unique functions including generating linear ubiquitin chains and ubiquitinating hydroxyl (versus canonical amine) residues, including of glycogen. In a mouse model we now show (i) that the amylopectinosis of RBCK1 deficiency, like in adult polyglucosan body disease and Lafora disease, affects the brain; (ii) that RBCK1 deficiency glycogen, like in adult polyglucosan body disease and Lafora disease, has overlong branches; (iii) that unlike adult polyglucosan body disease but like Lafora disease, RBCK1 deficiency glycogen is hyperphosphorylated; and finally (iv) that unlike laforin-deficient Lafora disease but like malin-deficient Lafora disease, RBCK1 deficiency's glycogen hyperphosphorylation is limited to precipitated polyglucosans. In summary, the fundamental glycogen pathology of RBCK1 deficiency recapitulates that of malin-deficient Lafora disease. Additionally, we uncover sex and genetic background effects in RBCK1 deficiency on organ- and brain-region specific amylopectinoses, and in the brain on consequent neuroinflammation and behavioural deficits. Finally, we exploit the portion of the basic glycogen pathology that is common to adult polyglucosan body disease, both forms of Lafora disease and RBCK1 deficiency, namely overlong branches, to show that a unified approach based on downregulating glycogen synthase, the enzyme that elongates glycogen branches, can rescue all four diseases.
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Affiliation(s)
- Silvia Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mitchell A Sullivan
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
- Glycation and Diabetes Complications, Mater Research Institute–The University of Queensland, Translational Research Institute, Brisbane, QLD, 4102, Australia
| | - Sharmistha Mitra
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Charlotte R Marchioni
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jennifer P Y Lee
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Brandon H Smith
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Saija Ahonen
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Jun Wu
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Erin E Chown
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Peixiang Wang
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Sara Petković
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Laura F DiGiovanni
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Lori Israelian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Tamar R Grossman
- Department of Antisense Drug Discovery, Ionis Pharmaceuticals, Carlsbad, California, USA
| | - Holly Kordasiewicz
- Department of Antisense Drug Discovery, Ionis Pharmaceuticals, Carlsbad, California, USA
| | - Francisco Vilaplana
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm 10691, Sweden
| | - Kazuhiro Iwai
- Department of Molecular and Cellular Physiology, Kyoto University School of Medicine, Kyoto 606-8501, Japan
| | - Felix Nitschke
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Berge A Minassian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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4
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McCorvie TJ, Loria PM, Tu M, Han S, Shrestha L, Froese DS, Ferreira IM, Berg AP, Yue WW. Molecular basis for the regulation of human glycogen synthase by phosphorylation and glucose-6-phosphate. Nat Struct Mol Biol 2022; 29:628-638. [PMID: 35835870 PMCID: PMC9287172 DOI: 10.1038/s41594-022-00799-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 05/02/2022] [Indexed: 11/17/2022]
Abstract
Glycogen synthase (GYS1) is the central enzyme in muscle glycogen biosynthesis. GYS1 activity is inhibited by phosphorylation of its amino (N) and carboxyl (C) termini, which is relieved by allosteric activation of glucose-6-phosphate (Glc6P). We present cryo-EM structures at 3.0-4.0 Å resolution of phosphorylated human GYS1, in complex with a minimal interacting region of glycogenin, in the inhibited, activated and catalytically competent states. Phosphorylations of specific terminal residues are sensed by different arginine clusters, locking the GYS1 tetramer in an inhibited state via intersubunit interactions. The Glc6P activator promotes conformational change by disrupting these interactions and increases the flexibility of GYS1, such that it is poised to adopt a catalytically competent state when the sugar donor UDP-glucose (UDP-glc) binds. We also identify an inhibited-like conformation that has not transitioned into the activated state, in which the locking interaction of phosphorylation with the arginine cluster impedes subsequent conformational changes due to Glc6P binding. Our results address longstanding questions regarding the mechanism of human GYS1 regulation.
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Affiliation(s)
- Thomas J McCorvie
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Paula M Loria
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Groton, CT, USA
| | - Meihua Tu
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA
| | - Seungil Han
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Groton, CT, USA
| | - Leela Shrestha
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - D Sean Froese
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Division of Metabolism and Children's Research Center, University Children's Hospital Zürich, University of Zürich, Zürich, Switzerland
| | - Igor M Ferreira
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Allison P Berg
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA.
| | - Wyatt W Yue
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
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5
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Liu Q, Li J, Zhang W, Xiao C, Zhang S, Nian C, Li J, Su D, Chen L, Zhao Q, Shao H, Zhao H, Chen Q, Li Y, Geng J, Hong L, Lin S, Wu Q, Deng X, Ke R, Ding J, Johnson RL, Liu X, Chen L, Zhou D. Glycogen accumulation and phase separation drives liver tumor initiation. Cell 2021; 184:5559-5576.e19. [PMID: 34678143 DOI: 10.1016/j.cell.2021.10.001] [Citation(s) in RCA: 124] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 05/31/2021] [Accepted: 09/30/2021] [Indexed: 12/16/2022]
Abstract
Glucose consumption is generally increased in tumor cells to support tumor growth. Interestingly, we report that glycogen accumulation is a key initiating oncogenic event during liver malignant transformation. We found that glucose-6-phosphatase (G6PC) catalyzing the last step of glycogenolysis is frequently downregulated to augment glucose storage in pre-malignant cells. Accumulated glycogen undergoes liquid-liquid phase separation, which results in the assembly of the Laforin-Mst1/2 complex and consequently sequesters Hippo kinases Mst1/2 in glycogen liquid droplets to relieve their inhibition on Yap. Moreover, G6PC or another glycogenolysis enzyme-liver glycogen phosphorylase (PYGL) deficiency in both human and mice results in glycogen storage disease along with liver enlargement and tumorigenesis in a Yap-dependent manner. Consistently, elimination of glycogen accumulation abrogates liver growth and cancer incidence, whereas increasing glycogen storage accelerates tumorigenesis. Thus, we concluded that cancer-initiating cells adapt a glycogen storing mode, which blocks Hippo signaling through glycogen phase separation to augment tumor incidence.
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Affiliation(s)
- Qingxu Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Jiaxin Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Weiji Zhang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Chen Xiao
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Shihao Zhang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Cheng Nian
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Junhong Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Dongxue Su
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Lihong Chen
- Department of Pathology, School of Basic Medical Sciences of Fujian Medical University, Fuzhou, Fujian 350004, China
| | - Qian Zhao
- Eastern Hepatobiliary Surgery Hospital/Institute, Second Military Medical University, Shanghai 200433, China
| | - Hui Shao
- School of Biomedical Sciences and School of Medicine, Huaqiao University, Quanzhou, Fujian 362021, China
| | - Hao Zhao
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Qinghua Chen
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Yuxi Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Jing Geng
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Lixin Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Shuhai Lin
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Qiao Wu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Xianming Deng
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Rongqin Ke
- School of Biomedical Sciences and School of Medicine, Huaqiao University, Quanzhou, Fujian 362021, China
| | - Jin Ding
- Eastern Hepatobiliary Surgery Hospital/Institute, Second Military Medical University, Shanghai 200433, China
| | - Randy L Johnson
- Department of Biochemistry and Molecular Biology, University of Texas, M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Xiaolong Liu
- The United Innovation of Mengchao Hepatobiliary Technology Key Laboratory of Fujian Province, Mengchao Hepatobiliary Hospital of Fujian Medical University, The Liver Center of Fujian Province, Fuzhou 350025, P.R. China
| | - Lanfen Chen
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
| | - Dawang Zhou
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
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6
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Lannoy V, Côté-Biron A, Asselin C, Rivard N. Phosphatases in toll-like receptors signaling: the unfairly-forgotten. Cell Commun Signal 2021; 19:10. [PMID: 33494775 PMCID: PMC7829650 DOI: 10.1186/s12964-020-00693-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 12/01/2020] [Indexed: 02/07/2023] Open
Abstract
Over the past 2 decades, pattern recognition receptors (PRRs) have been shown to be on the front line of many illnesses such as autoimmune, inflammatory, and neurodegenerative diseases as well as allergies and cancer. Among PRRs, toll-like receptors (TLRs) are the most studied family. Dissecting TLRs signaling turned out to be advantageous to elaborate efficient treatments to cure autoimmune and chronic inflammatory disorders. However, a broad understanding of TLR effectors is required to propose a better range of cures. In addition to kinases and E3 ubiquitin ligases, phosphatases emerge as important regulators of TLRs signaling mediated by NF-κB, type I interferons (IFN I) and Mitogen-Activated Protein Kinases signaling pathways. Here, we review recent knowledge on TLRs signaling modulation by different classes and subclasses of phosphatases. Thus, it becomes more and more evident that phosphatases could represent novel therapeutic targets to control pathogenic TLRs signaling. Video Abstract.
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Affiliation(s)
- Valérie Lannoy
- Department of Immunology and Cell Biology, Cancer Research Pavilion, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC, J1E4K8, Canada
| | - Anthony Côté-Biron
- Department of Immunology and Cell Biology, Cancer Research Pavilion, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC, J1E4K8, Canada
| | - Claude Asselin
- Department of Immunology and Cell Biology, Cancer Research Pavilion, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC, J1E4K8, Canada
| | - Nathalie Rivard
- Department of Immunology and Cell Biology, Cancer Research Pavilion, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201, rue Jean Mignault, Sherbrooke, QC, J1E4K8, Canada.
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7
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The Protein Phosphatase 1 Complex Is a Direct Target of AKT that Links Insulin Signaling to Hepatic Glycogen Deposition. Cell Rep 2020; 28:3406-3422.e7. [PMID: 31553910 DOI: 10.1016/j.celrep.2019.08.066] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 06/02/2019] [Accepted: 08/21/2019] [Indexed: 11/24/2022] Open
Abstract
Insulin-stimulated hepatic glycogen synthesis is central to glucose homeostasis. Here, we show that PPP1R3G, a regulatory subunit of protein phosphatase 1 (PP1), is directly phosphorylated by AKT. PPP1R3G phosphorylation fluctuates with fasting-refeeding cycle and is required for insulin-stimulated dephosphorylation, i.e., activation of glycogen synthase (GS) in hepatocytes. In this study, we demonstrate that knockdown of PPP1R3G significantly inhibits insulin response. The introduction of wild-type PPP1R3G, and not phosphorylation-defective mutants, increases hepatic glycogen deposition, blood glucose clearance, and insulin sensitivity in vivo. Mechanistically, phosphorylated PPP1R3G displays increased binding for, and promotes dephosphorylation of, phospho-GS. Furthermore, PPP1R3B, another regulatory subunit of PP1, binds to the dephosphorylated GS, thereby relaying insulin stimulation to hepatic glycogen deposition. Importantly, this PP1-mediated signaling cascade is independent of GSK3. Therefore, we reveal a regulatory axis consisting of insulin/AKT/PPP1R3G/PPP1R3B that operates in parallel to the GSK3-dependent pathway, controlling glycogen synthesis and glucose homeostasis in insulin signaling.
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8
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Casamayor A, Ariño J. Controlling Ser/Thr protein phosphatase PP1 activity and function through interaction with regulatory subunits. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2020; 122:231-288. [PMID: 32951813 DOI: 10.1016/bs.apcsb.2020.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protein phosphatase 1 is a major Ser/Thr protein phosphatase activity in eukaryotic cells. It is composed of a catalytic polypeptide (PP1C), with little substrate specificity, that interacts with a large variety of proteins of diverse structure (regulatory subunits). The diversity of holoenzymes that can be formed explain the multiplicity of cellular functions under the control of this phosphatase. In quite a few cases, regulatory subunits have an inhibitory role, downregulating the activity of the phosphatase. In this chapter we shall introduce PP1C and review the most relevant families of PP1C regulatory subunits, with particular emphasis in describing the structural basis for their interaction.
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Affiliation(s)
- Antonio Casamayor
- Institut de Biotecnologia i Biomedicina & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola, del Vallès, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola, del Vallès, Spain
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9
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Ma LY, Liu SF, Du JH, Niu Y, Hou PF, Shu Q, Ma RR, Wu SD, Qu QM, Lv YL. Chronic ghrelin administration suppresses IKK/NF-κB/BACE1 mediated Aβ production in primary neurons and improves cognitive function via upregulation of PP1 in STZ-diabetic rats. Neurobiol Learn Mem 2020; 169:107155. [PMID: 31904547 DOI: 10.1016/j.nlm.2019.107155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 11/19/2019] [Accepted: 12/31/2019] [Indexed: 01/19/2023]
Abstract
Diabetic rats display cognition impairments accompanied by activation of NF-κB signalling and increased Aβ expression. Ghrelin has been suggested to improve cognition in diabetic rats. In this study, we investigated the role of ghrelin on cognition and NF-κB mediated Aβ production in diabetic rats. A diabetic rat model was established with streptozotocin (STZ) injection, and diabetic rats were intracerebroventricularly administered with ghrelin or (D-lys3)-GHRP-6 (DG). Our results showed that diabetic rats had cognition impairment in the Morris water maze test, accompanied by the higher expression of Aβ in the hippocampus. Western blot analysis showed that diabetic rats exhibited significantly decreased levels of GHSR-1a and protein phosphatase 1 (PP1) in the hippocampus and increased activation of the IKK/NF-κB/BACE1 pathway. Chronic ghrelin administration upregulated hippocampal PP1 expression, suppressed IKK/NF-κB/BACE1 mediated Aβ production, and improved cognition in STZ-induced diabetic rats. These effects were reversed by DG. Then, primary rat hippocampal neurons were isolated and treated with high glucose, followed by Ghrelin and DG, PP1 or IKK. Similar to the in vivo results, high glucose suppressed the expression levels of GHSR-1a and PP1, activated the IKK/NF-κB/BACE1 pathway, increased Aβ production. Ghrelin suppressed IKK/NF-κB/BACE1 induced Aβ production. This improvement was reversed by DG and a PP1 antagonist and was enhanced by the IKK antagonist. Our findings indicated that chronic ghrelin administration can suppress IKK/NF-κB/BACE1 mediated Aβ production in primary neurons with high glucose treatment and improve the cognition via PP1 upregulation in diabetic rats.
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Affiliation(s)
- Lou-Yan Ma
- The Second Department of Geriatrics, Ninth Hospital of Xi'an, Xi'an, China
| | - Song-Fang Liu
- Department of Endocrinology, Ninth Hospital of Xi'an, Xi'an, China
| | - Jun-Hui Du
- Department of Ophthalmology, Ninth Hospital of Xi'an, Xi'an, China
| | - Yu Niu
- Department of Endocrinology, Ninth Hospital of Xi'an, Xi'an, China
| | - Peng-Fei Hou
- Department of Neurosurgery, Ninth Hospital of Xi'an, Xi'an, China
| | - Qing Shu
- Department of Pharmacy, Ninth Hospital of Xi'an, Xi'an, China
| | - Ran-Ran Ma
- Department of Neurology, Ninth Hospital of Xi'an, Xi'an, China
| | - Song-Di Wu
- Department of Neurology, First Hospital of Xi'an, Xi'an, China.
| | - Qiu-Min Qu
- Department of Neurology, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
| | - Ya-Li Lv
- Department of Neurology, Fourth Hospital of Xi'an, Xi'an, China.
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10
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Ochsner SA, Abraham D, Martin K, Ding W, McOwiti A, Kankanamge W, Wang Z, Andreano K, Hamilton RA, Chen Y, Hamilton A, Gantner ML, Dehart M, Qu S, Hilsenbeck SG, Becnel LB, Bridges D, Ma'ayan A, Huss JM, Stossi F, Foulds CE, Kralli A, McDonnell DP, McKenna NJ. The Signaling Pathways Project, an integrated 'omics knowledgebase for mammalian cellular signaling pathways. Sci Data 2019; 6:252. [PMID: 31672983 PMCID: PMC6823428 DOI: 10.1038/s41597-019-0193-4] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 09/11/2019] [Indexed: 12/28/2022] Open
Abstract
Mining of integrated public transcriptomic and ChIP-Seq (cistromic) datasets can illuminate functions of mammalian cellular signaling pathways not yet explored in the research literature. Here, we designed a web knowledgebase, the Signaling Pathways Project (SPP), which incorporates community classifications of signaling pathway nodes (receptors, enzymes, transcription factors and co-nodes) and their cognate bioactive small molecules. We then mapped over 10,000 public transcriptomic or cistromic experiments to their pathway node or biosample of study. To enable prediction of pathway node-gene target transcriptional regulatory relationships through SPP, we generated consensus 'omics signatures, or consensomes, which ranked genes based on measures of their significant differential expression or promoter occupancy across transcriptomic or cistromic experiments mapped to a specific node family. Consensomes were validated using alignment with canonical literature knowledge, gene target-level integration of transcriptomic and cistromic data points, and in bench experiments confirming previously uncharacterized node-gene target regulatory relationships. To expose the SPP knowledgebase to researchers, a web browser interface was designed that accommodates numerous routine data mining strategies. SPP is freely accessible at https://www.signalingpathways.org .
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Affiliation(s)
- Scott A Ochsner
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - David Abraham
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Kirt Martin
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Wei Ding
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Apollo McOwiti
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Wasula Kankanamge
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Zichen Wang
- Icahn School of Medicine, Mount Sinai University, New York, NY, 10029, USA
| | - Kaitlyn Andreano
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Ross A Hamilton
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Yue Chen
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Angelica Hamilton
- Diabetes & Metabolism Research Institute, City of Hope, Duarte, CA, 91010, USA
| | - Marin L Gantner
- Department of Chemical Physiology, Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Michael Dehart
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Shijing Qu
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Susan G Hilsenbeck
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Lauren B Becnel
- Duncan NCI Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Dave Bridges
- University of Michigan School of Public Health, Ann Arbor, MI, 48109, USA
| | - Avi Ma'ayan
- Icahn School of Medicine, Mount Sinai University, New York, NY, 10029, USA
| | - Janice M Huss
- Diabetes & Metabolism Research Institute, City of Hope, Duarte, CA, 91010, USA
| | - Fabio Stossi
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Charles E Foulds
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Anastasia Kralli
- Department of Chemical Physiology, Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Donald P McDonnell
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Neil J McKenna
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA.
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11
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Abstract
Lafora disease is a severe, autosomal recessive, progressive myoclonus epilepsy. The disease usually manifests in previously healthy adolescents, and death commonly occurs within 10 years of symptom onset. Lafora disease is caused by loss-of-function mutations in EPM2A or NHLRC1, which encode laforin and malin, respectively. The absence of either protein results in poorly branched, hyperphosphorylated glycogen, which precipitates, aggregates and accumulates into Lafora bodies. Evidence from Lafora disease genetic mouse models indicates that these intracellular inclusions are a principal driver of neurodegeneration and neurological disease. The integration of current knowledge on the function of laforin-malin as an interacting complex suggests that laforin recruits malin to parts of glycogen molecules where overly long glucose chains are forming, so as to counteract further chain extension. In the absence of either laforin or malin function, long glucose chains in specific glycogen molecules extrude water, form double helices and drive precipitation of those molecules, which over time accumulate into Lafora bodies. In this article, we review the genetic, clinical, pathological and molecular aspects of Lafora disease. We also discuss traditional antiseizure treatments for this condition, as well as exciting therapeutic advances based on the downregulation of brain glycogen synthesis and disease gene replacement.
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12
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Milotic M, Milotic D, Koprivnikar J. Effects of a Cyanobacterial Toxin on Trematode Cercariae. J Parasitol 2019. [DOI: 10.1645/18-170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Marin Milotic
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
| | - Dino Milotic
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
| | - Janet Koprivnikar
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
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13
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NURR1 activation in skeletal muscle controls systemic energy homeostasis. Proc Natl Acad Sci U S A 2019; 116:11299-11308. [PMID: 31110021 DOI: 10.1073/pnas.1902490116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Skeletal muscle plays a central role in the control of metabolism and exercise tolerance. Analysis of muscle enhancers activated after exercise in mice revealed the orphan nuclear receptor NURR1/NR4A2 as a prominent component of exercise-responsive enhancers. We show that exercise enhances the expression of NURR1, and transgenic overexpression of NURR1 in skeletal muscle enhances physical performance in mice. NURR1 expression in skeletal muscle is also sufficient to prevent hyperglycemia and hepatic steatosis, by enhancing muscle glucose uptake and storage as glycogen. Furthermore, treatment of obese mice with putative NURR1 agonists increases energy expenditure, improves glucose tolerance, and confers a lean phenotype, mimicking the effects of exercise. These findings identify a key role for NURR1 in governance of skeletal muscle glucose metabolism, and reveal a transcriptional link between exercise and metabolism. Our findings also identify NURR1 agonists as possible exercise mimetics with the potential to ameliorate obesity and other metabolic abnormalities.
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14
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Liu S, Li L, Meng J, Song K, Huang B, Wang W, Zhang G. Association and Functional Analyses Revealed That PPP1R3B Plays an Important Role in the Regulation of Glycogen Content in the Pacific Oyster Crassostrea gigas. Front Genet 2019; 10:106. [PMID: 30853975 PMCID: PMC6396720 DOI: 10.3389/fgene.2019.00106] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/30/2019] [Indexed: 12/15/2022] Open
Abstract
The Pacific oyster (Crassostrea gigas) is one of the most important aquaculture species worldwide. Glycogen contributes greatly to the special taste and creamy white color of oysters. Previous genome-wide association studies (GWAS) identified several single nucleotide polymorphism (SNP) sites that were strongly related to glycogen content. Genes within 100 kb upstream and downstream of the associated SNPs were screened. One gene annotated as protein phosphatase 1 regulatory subunit 3B (PPP1R3B), which can promote glycogen synthesis together with protein phosphatase 1 catalytic subunit (PPP1C) in mammals, was selected as a candidate gene in this study. First, full-length CgPPP1R3B was cloned and its function was characterized. The gene expression profiles of CgPPP1R3B in different tissues and seasons showed a close relationship to glycogen content. RNA interference (RNAi) experiments of this gene in vivo showed that decreased CgPPP1R3B levels resulted in lower glycogen contents in the experimental group than in the control group. Co-immunoprecipitation (Co-IP) and yeast two-hybrid (Y2H) assays indicated that CgPPP1R3B can interact with CgPPP1C, glycogen synthase (CgGS) and glycogen phosphorylase (CgGP), thus participating in glycogen metabolism. Co-sedimentation analysis in vitro demonstrated that the CgPPP1R3B protein can bind to glycogen molecules directly, and these results indicated the conserved function of the CgPPP1R3B protein compared to that of mammals. In addition, thirteen SNPs were precisely mapped in this gene. Ten of the thirteen SNPs were confirmed to be significantly (p < 0.05) related to glycogen content in an independent wild population (n = 288). The CgPPP1R3B levels in oysters with high glycogen content were significantly higher than those of oysters with low glycogen content, and gene expression levels were significantly associated with various genotypes of four associated SNPs (p < 0.05). The data indicated that the associated SNPs may control glycogen content by regulating CgPPP1R3B expression. These results suggest that CgPPP1R3B is an important gene for glycogen metabolic regulation and that the associated SNPs of this gene are potential markers for oyster molecular breeding for increased glycogen content.
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Affiliation(s)
- Sheng Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Li Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,National and Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Jie Meng
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,National and Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Kai Song
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,National and Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Baoyu Huang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,National and Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Wei Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,National and Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Guofan Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,National and Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
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15
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Yu J, Deng T, Xiang S. Structural basis for protein phosphatase 1 recruitment by glycogen‐targeting subunits. FEBS J 2018; 285:4646-4659. [DOI: 10.1111/febs.14699] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 10/15/2018] [Accepted: 11/09/2018] [Indexed: 10/27/2022]
Affiliation(s)
- Jun Yu
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety Shanghai Institute of Nutrition and Health Shanghai Institutes for Biological Sciences University of Chinese Academy of Sciences Chinese Academy of Sciences Shanghai China
| | - Tingting Deng
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety Shanghai Institute of Nutrition and Health Shanghai Institutes for Biological Sciences University of Chinese Academy of Sciences Chinese Academy of Sciences Shanghai China
| | - Song Xiang
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety Shanghai Institute of Nutrition and Health Shanghai Institutes for Biological Sciences University of Chinese Academy of Sciences Chinese Academy of Sciences Shanghai China
- Key laboratory of Immune Microenvironment and Disease (Ministry of Education) Tianjin Medical University China
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16
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Kumar GS, Choy MS, Koveal DM, Lorinsky MK, Lyons SP, Kettenbach AN, Page R, Peti W. Identification of the substrate recruitment mechanism of the muscle glycogen protein phosphatase 1 holoenzyme. SCIENCE ADVANCES 2018; 4:eaau6044. [PMID: 30443599 PMCID: PMC6235537 DOI: 10.1126/sciadv.aau6044] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/15/2018] [Indexed: 05/04/2023]
Abstract
Glycogen is the primary storage form of glucose. Glycogen synthesis and breakdown are tightly controlled by glycogen synthase (GYS) and phosphorylase, respectively. The enzyme responsible for dephosphorylating GYS and phosphorylase, which results in their activation (GYS) or inactivation (phosphorylase) to robustly stimulate glycogen synthesis, is protein phosphatase 1 (PP1). However, our understanding of how PP1 recruits these substrates is limited. Here, we show how PP1, together with its muscle glycogen-targeting (GM) regulatory subunit, recruits and selectively dephosphorylates its substrates. Our molecular data reveal that the GM carbohydrate binding module (GM CBM21), which is amino-terminal to the GM PP1 binding domain, has a dual function in directing PP1 substrate specificity: It either directly recruits substrates (i.e., GYS) or recruits them indirectly by localization (via glycogen for phosphorylase). Our data provide the molecular basis for PP1 regulation by GM and reveal how PP1-mediated dephosphorylation is driven by scaffolding-based substrate recruitment.
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Affiliation(s)
- Ganesan Senthil Kumar
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Meng S. Choy
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Dorothy M. Koveal
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Michael K. Lorinsky
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA
| | - Scott P. Lyons
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Arminja N. Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Rebecca Page
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Wolfgang Peti
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Corresponding author.
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17
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Kakhlon O, Ferreira I, Solmesky LJ, Khazanov N, Lossos A, Alvarez R, Yetil D, Pampou S, Weil M, Senderowitz H, Escriba P, Yue WW, Akman HO. Guaiacol as a drug candidate for treating adult polyglucosan body disease. JCI Insight 2018; 3:99694. [PMID: 30185673 DOI: 10.1172/jci.insight.99694] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 07/31/2018] [Indexed: 12/29/2022] Open
Abstract
Adult polyglucosan body disease (APBD) is a late-onset disease caused by intracellular accumulation of polyglucosan bodies, formed due to glycogen-branching enzyme (GBE) deficiency. To find a treatment for APBD, we screened 1,700 FDA-approved compounds in fibroblasts derived from APBD-modeling GBE1-knockin mice. Capitalizing on fluorescent periodic acid-Schiff reagent, which interacts with polyglucosans in the cell, this screen discovered that the flavoring agent guaiacol can lower polyglucosans, a result also confirmed in APBD patient fibroblasts. Biochemical assays showed that guaiacol lowers basal and glucose 6-phosphate-stimulated glycogen synthase (GYS) activity. Guaiacol also increased inactivating GYS1 phosphorylation and phosphorylation of the master activator of catabolism, AMP-dependent protein kinase. Guaiacol treatment in the APBD mouse model rescued grip strength and shorter lifespan. These treatments had no adverse effects except making the mice slightly hyperglycemic, possibly due to the reduced liver glycogen levels. In addition, treatment corrected penile prolapse in aged GBE1-knockin mice. Guaiacol's curative effects can be explained by its reduction of polyglucosans in peripheral nerve, liver, and heart, despite a short half-life of up to 60 minutes in most tissues. Our results form the basis to use guaiacol as a treatment and prepare for the clinical trials in APBD.
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Affiliation(s)
- Or Kakhlon
- Department of Neurology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Igor Ferreira
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Leonardo J Solmesky
- Cell Screening Facility for Personalized Medicine, Department of Cell Research and Immunology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Netaly Khazanov
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Alexander Lossos
- Department of Neurology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Rafael Alvarez
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Palma de Mallorca, Spain
| | - Deniz Yetil
- Connecticut College, Newington, Connecticut USA
| | - Sergey Pampou
- Columbia University Department of Systems Biology Irving Cancer Research Center, New York, New York, USA
| | - Miguel Weil
- Cell Screening Facility for Personalized Medicine, Department of Cell Research and Immunology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Laboratory for Neurodegenerative Diseases and Personalized Medicine, Department of Cell Research and Immunology, The George S. Wise Faculty for Life Sciences, Sagol School of Neurosciences, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | | | - Pablo Escriba
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Palma de Mallorca, Spain
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - H Orhan Akman
- Columbia University Medical Center Department of Neurology, Houston Merritt Neuromuscular diseases research center, New York, New York, USA
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18
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Exposure to a cyanobacterial toxin increases larval amphibian susceptibility to parasitism. Parasitol Res 2017; 117:513-520. [PMID: 29270769 DOI: 10.1007/s00436-017-5727-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 12/15/2017] [Indexed: 10/18/2022]
Abstract
Anthropogenic activities are promoting the proliferation of aquatic primary producers in freshwater habitats, including cyanobacteria. Among various problems stemming from eutrophication, cyanobacterial blooms can be toxic due to the production of secondary compounds, including microcystins such as microcystin-LR (MC-LR); however, it is unknown whether cyanotoxins can affect the susceptibility of aquatic vertebrates such as fish and larval amphibians to parasites or pathogens even though infectious diseases can significantly affect natural populations. Here, we examined how exposure to environmentally relevant concentrations of MC-LRs affected the resistance of larval amphibians (northern leopard frog, Rana pipiens) to infection by a helminth parasite (the trematode Echinostoma sp.), and whether this was manifested by reductions in host anti-parasite behavior. Exposure to a relatively high (82 μg L-1) concentration of MC-LR caused over 70% mortality, and tadpoles that survived exposure to the low MC-LR (11 μg L-1) treatment had significantly higher infection intensities than those in the control; however, anti-parasite behavior was not affected by treatment. Our results indicate that MC-LR can have both direct and indirect negative effects on larval amphibians by increasing their mortality and susceptibility to parasitism, which may have implications for other aquatic vertebrates in eutrophic habitats dominated by cyanobacteria as well.
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19
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Pathogenesis of Lafora Disease: Transition of Soluble Glycogen to Insoluble Polyglucosan. Int J Mol Sci 2017; 18:ijms18081743. [PMID: 28800070 PMCID: PMC5578133 DOI: 10.3390/ijms18081743] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 08/04/2017] [Accepted: 08/06/2017] [Indexed: 02/07/2023] Open
Abstract
Lafora disease (LD, OMIM #254780) is a rare, recessively inherited neurodegenerative disease with adolescent onset, resulting in progressive myoclonus epilepsy which is fatal usually within ten years of symptom onset. The disease is caused by loss-of-function mutations in either of the two genes EPM2A (laforin) or EPM2B (malin). It characteristically involves the accumulation of insoluble glycogen-derived particles, named Lafora bodies (LBs), which are considered neurotoxic and causative of the disease. The pathogenesis of LD is therefore centred on the question of how insoluble LBs emerge from soluble glycogen. Recent data clearly show that an abnormal glycogen chain length distribution, but neither hyperphosphorylation nor impairment of general autophagy, strictly correlates with glycogen accumulation and the presence of LBs. This review summarizes results obtained with patients, mouse models, and cell lines and consolidates apparent paradoxes in the LD literature. Based on the growing body of evidence, it proposes that LD is predominantly caused by an impairment in chain-length regulation affecting only a small proportion of the cellular glycogen. A better grasp of LD pathogenesis will further develop our understanding of glycogen metabolism and structure. It will also facilitate the development of clinical interventions that appropriately target the underlying cause of LD.
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20
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Kecmanović M, Keckarević-Marković M, Keckarević D, Stevanović G, Jović N, Romac S. Genetics of Lafora progressive myoclonic epilepsy: current perspectives. APPLICATION OF CLINICAL GENETICS 2016; 9:49-53. [PMID: 27194917 PMCID: PMC4859416 DOI: 10.2147/tacg.s57890] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Lafora disease (LD) is a fatal neurodegenerative disorder caused by loss-of-function mutations in either laforin glycogen phosphatase gene (EPM2A) or malin E3 ubiquitin ligase gene (NHLRC1). LD is associated with gradual accumulation of Lafora bodies (LBs). LBs are aggregates of polyglucosan, a long, linear, poorly branched, hyperphosphorylated, insoluble form of glycogen. Loss-of-function mutations either in the EPM2A or in the NHLRC1 gene lead to polyglucosan formation. One hypothesis on LB formation is based on findings that laforin–malin complex downregulates glycogen synthase (GS) through malin-mediated ubiquitination, and the other one is based on findings that laforin dephosphorylates glycogen. According to the first hypothesis, polyglucosan formation is a result of increased GS activity, and according to the second, an increased glycogen phosphate leads to glycogen conformational change, unfolding, precipitation, and conversion to polyglucosan, while GS remains bound to the precipitating glycogen. In this review, we summarize all the recent findings that have important implications for the treatment of LD, all of them showing that partial inhibition of GS activity may be sufficient to prevent the progression of the disease. The current perspective in LD is high-throughput screening for small molecules that act on the disease pathway, that is, partial inhibitors of GS, which opens a therapeutic window for potential treatment of this fatal disease.
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Affiliation(s)
- Miljana Kecmanović
- Faculty of Biology, Center for Human Molecular Genetics, University of Belgrade, Belgrade, Serbia
| | | | - Dušan Keckarević
- Faculty of Biology, Center for Human Molecular Genetics, University of Belgrade, Belgrade, Serbia
| | - Galina Stevanović
- Clinic of Neurology and Psychiatry for Children and Youth, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Nebojša Jović
- Clinic of Neurology and Psychiatry for Children and Youth, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Stanka Romac
- Faculty of Biology, Center for Human Molecular Genetics, University of Belgrade, Belgrade, Serbia
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21
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The interaction between AMPKβ2 and the PP1-targeting subunit R6 is dynamically regulated by intracellular glycogen content. Biochem J 2016; 473:937-47. [DOI: 10.1042/bj20151035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 02/01/2016] [Indexed: 11/17/2022]
Abstract
Breakdown of intracellular glycogen enhances interaction of the AMPKβ2 subunit and the R6 glycogen-targeting subunit of protein phosphatase type 1 (PP1), which occurs in conjunction with increased β2-Thr-148 phosphorylation.
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22
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Role of glycogen phosphorylase in liver glycogen metabolism. Mol Aspects Med 2015; 46:34-45. [PMID: 26519772 DOI: 10.1016/j.mam.2015.09.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 02/05/2023]
Abstract
Liver glycogen is synthesized after a meal in response to an increase in blood glucose concentration in the portal vein and endocrine and neuroendocrine signals, and is degraded to glucose between meals to maintain blood glucose homeostasis. Glycogen degradation and synthesis during the diurnal cycle are mediated by changes in the activities of phosphorylase and glycogen synthase. Phosphorylase is regulated by phosphorylation of serine-14. Only the phosphorylated form of liver phosphorylase (GPa) is catalytically active. Interconversion between GPa and GPb (unphosphorylated) is dependent on the activities of phosphorylase kinase and of phosphorylase phosphatase. The latter comprises protein phosphatase-1 in conjunction with a glycogen-targeting protein (G-subunit) of the PPP1R3 family. At least two of six G-subunits (GL and PTG) expressed in liver are involved in GPa dephosphorylation. GPa to GPb interconversion is dependent on the conformational state of phosphorylase which can be relaxed (R) or tense (T) depending on the concentrations of allosteric effectors such as glucose, glucose 6-phosphate and adenine nucleotides and on the acetylation state of lysine residues. The G-subunit, GL, encoded by PPP1R3B gene is expressed at high levels in liver and can function as a phosphorylase phosphatase and a synthase phosphatase and has an allosteric binding site for GPa at the C-terminus which inhibits synthase phosphatase activity. GPa to GPb conversion is a major upstream event in the regulation of glycogen synthesis by glucose, its downstream metabolites and extracellular signals such as insulin and neurotransmitters.
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Rubio-Villena C, Sanz P, Garcia-Gimeno MA. Structure-Function Analysis of PPP1R3D, a Protein Phosphatase 1 Targeting Subunit, Reveals a Binding Motif for 14-3-3 Proteins which Regulates its Glycogenic Properties. PLoS One 2015; 10:e0131476. [PMID: 26114292 PMCID: PMC4482762 DOI: 10.1371/journal.pone.0131476] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/01/2015] [Indexed: 01/20/2023] Open
Abstract
Protein phosphatase 1 (PP1) is one of the major protein phosphatases in eukaryotic cells. It plays a key role in regulating glycogen synthesis, by dephosphorylating crucial enzymes involved in glycogen homeostasis such as glycogen synthase (GS) and glycogen phosphorylase (GP). To play this role, PP1 binds to specific glycogen targeting subunits that, on one hand recognize the substrates to be dephosphorylated and on the other hand recruit PP1 to glycogen particles. In this work we have analyzed the functionality of the different protein binding domains of one of these glycogen targeting subunits, namely PPP1R3D (R6) and studied how binding properties of different domains affect its glycogenic properties. We have found that the PP1 binding domain of R6 comprises a conserved RVXF motif (R102VRF) located at the N-terminus of the protein. We have also identified a region located at the C-terminus of R6 (W267DNND) that is involved in binding to the PP1 glycogenic substrates. Our results indicate that although binding to PP1 and glycogenic substrates are independent processes, impairment of any of them results in lack of glycogenic activity of R6. In addition, we have characterized a novel site of regulation in R6 that is involved in binding to 14-3-3 proteins (RARS74LP). We present evidence indicating that when binding of R6 to 14-3-3 proteins is prevented, R6 displays hyper-glycogenic activity although is rapidly degraded by the lysosomal pathway. These results define binding to 14-3-3 proteins as an additional pathway in the control of the glycogenic properties of R6.
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Affiliation(s)
- Carla Rubio-Villena
- Instituto de Biomedicina de Valencia, CSIC, and Centro de Investigación en Red de Enfermedades Raras (CIBERER), Jaime Roig 11, Valencia, Spain
| | - Pascual Sanz
- Instituto de Biomedicina de Valencia, CSIC, and Centro de Investigación en Red de Enfermedades Raras (CIBERER), Jaime Roig 11, Valencia, Spain
- * E-mail:
| | - Maria Adelaida Garcia-Gimeno
- Instituto de Biomedicina de Valencia, CSIC, and Centro de Investigación en Red de Enfermedades Raras (CIBERER), Jaime Roig 11, Valencia, Spain
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Pederson BA, Turnbull J, Epp JR, Weaver SA, Zhao X, Pencea N, Roach PJ, Frankland PW, Ackerley CA, Minassian BA. Inhibiting glycogen synthesis prevents Lafora disease in a mouse model. Ann Neurol 2014; 74:297-300. [PMID: 23913475 DOI: 10.1002/ana.23899] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/05/2013] [Accepted: 03/15/2013] [Indexed: 11/10/2022]
Abstract
Lafora disease (LD) is a fatal progressive myoclonus epilepsy characterized neuropathologically by aggregates of abnormally structured glycogen and proteins (Lafora bodies [LBs]), and neurodegeneration. Whether LBs could be prevented by inhibiting glycogen synthesis and whether they are pathogenic remain uncertain. We genetically eliminated brain glycogen synthesis in LD mice. This resulted in long-term prevention of LB formation, neurodegeneration, and seizure susceptibility. This study establishes that glycogen synthesis is requisite for LB formation and that LBs are pathogenic. It opens a therapeutic window for potential treatments in LD with known and future small molecule inhibitors of glycogen synthesis.
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25
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Leiherer A, Geiger K, Muendlein A, Drexel H. Hypoxia induces a HIF-1α dependent signaling cascade to make a complex metabolic switch in SGBS-adipocytes. Mol Cell Endocrinol 2014; 383:21-31. [PMID: 24275182 PMCID: PMC3969228 DOI: 10.1016/j.mce.2013.11.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/18/2013] [Accepted: 11/15/2013] [Indexed: 12/11/2022]
Abstract
To elucidate the complex impact of hypoxia on adipose tissue, resulting in biased metabolism, insulin resistance and finally diabetes we used mature adipocytes derived from a Simpson-Golabi-Behmel syndrome patient for microarray analysis. We found a significantly increased transcription rate of genes involved in glycolysis and a striking association between the pattern of upregulated genes and disease biomarkers for diabetes mellitus and insulin resistance. Although their upregulation turned out to be HIF-1α-dependent, we identified further transcription factors mainly AP-1 components to play also an important role in hypoxia response. Analyzing the regulatory network of mentioned transcription factors and glycolysis targets we revealed a clear hint for directing glycolysis to glutathione and glycogen synthesis. This metabolic switch in adipocytes enables the cell to prevent oxidative damage in the short term but might induce lipogenesis and establish systemic metabolic disorders in the long run.
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MESH Headings
- Adipocytes/metabolism
- Adipocytes/pathology
- Adipogenesis
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/pathology
- Biomarkers/metabolism
- Cell Hypoxia/genetics
- Gene Expression Profiling
- Gene Expression Regulation
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- Genetic Diseases, X-Linked/pathology
- Gigantism/genetics
- Gigantism/metabolism
- Gigantism/pathology
- Glutathione/biosynthesis
- Glycogen/biosynthesis
- Glycolysis
- Heart Defects, Congenital/genetics
- Heart Defects, Congenital/metabolism
- Heart Defects, Congenital/pathology
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Insulin Resistance
- Intellectual Disability/genetics
- Intellectual Disability/metabolism
- Intellectual Disability/pathology
- Oligonucleotide Array Sequence Analysis
- Protein Interaction Mapping
- Signal Transduction/genetics
- Transcription Factor AP-1/genetics
- Transcription Factor AP-1/metabolism
- Transcription, Genetic
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Affiliation(s)
- Andreas Leiherer
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria; Private University of the Principality of Liechtenstein, Triesen, Liechtenstein; Medical Central Laboratories, Feldkirch, Austria
| | - Kathrin Geiger
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria; Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Axel Muendlein
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria; Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Heinz Drexel
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria; Department of Medicine and Cardiology, Academic Teaching Hospital Feldkirch, Feldkirch, Austria; Private University of the Principality of Liechtenstein, Triesen, Liechtenstein; Drexel University College of Medicine, Philadelphia, USA.
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26
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Magnetite- and maghemite-induced different toxicity in murine alveolar macrophage cells. Arch Toxicol 2014; 88:1607-18. [PMID: 24525745 DOI: 10.1007/s00204-014-1210-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 01/29/2014] [Indexed: 12/14/2022]
Abstract
The unique properties of nanoparticles and biological systems are important factors affecting the biological response following nanoparticle exposure. Iron oxide nanoparticles are classified mainly as magnetite (M-FeNPs) and maghemite (NM-FeNPs). In our previous study, NM-FeNPs induced autophagic cell death in RAW264.7, a murine peritoneal macrophage cell line, which has excellent lysosomal activity. In this study, we compared the toxicity of M-FeNPs and NM-FeNPs in MH-S, a murine alveolar macrophage cell line, which has relatively low lysosomal activity. At 24 h post-exposure, M-FeNPs decreased cell viability and ATP production, and elevated the levels of reactive oxygen species, nitric oxide, and pro-inflammatory cytokines to a higher extent than NM-FeNPs. Damage of mitochondria and the endoplasmic reticulum and the down-regulation of mitochondrial function and transcription-related genes were also higher in cells exposed to M-FeNPs than in cells exposed to NM-FeNPs (50 μg/ml). In addition, cells exposed to M-FeNPs (50 μg/ml) showed an increase in the number of autophagosome-like vacuoles, whereas cells exposed to NM-FeNPs formed large vacuoles in the cytosol. However, an autophagy-related molecular response was not induced by exposure to either FeNPs, unlike the results seen in our previous study with RAW264.7 cells. We suggest that M-FeNPs induced higher toxicity compared to NM-FeNPs in MH-S cells, and lysosomal activity plays an important role in determining cell death pathway.
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27
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Identification of cellular proteins that interact with human cytomegalovirus immediate-early protein 1 by protein array assay. Viruses 2013; 6:89-105. [PMID: 24385082 PMCID: PMC3917433 DOI: 10.3390/v6010089] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 12/10/2013] [Accepted: 12/20/2013] [Indexed: 12/13/2022] Open
Abstract
Human cytomegalovirus (HCMV) gene expression during infection is characterized as a sequential process including immediate-early (IE), early (E), and late (L)-stage gene expression. The most abundantly expressed gene at the IE stage of infection is the major IE (MIE) gene that produces IE1 and IE2. IE1 has been the focus of study because it is an important protein, not only for viral gene expression but also for viral replication. It is believed that IE1 plays important roles in viral gene regulation by interacting with cellular proteins. In the current study, we performed protein array assays and identified 83 cellular proteins that interact with IE1. Among them, seven are RNA-binding proteins that are important in RNA processing; more than half are nuclear proteins that are involved in gene regulations. Tumorigenesis-related proteins are also found to interact with IE1, implying that the role of IE1 in tumorigenesis might need to be reevaluated. Unexpectedly, cytoplasmic proteins, such as Golgi autoantigen and GGA1 (both related to the Golgi trafficking protein), are also found to be associated with IE1. We also employed a coimmunoprecipitation assay to test the interactions of IE1 and some of the proteins identified in the protein array assays and confirmed that the results from the protein array assays are reliable. Many of the proteins identified by the protein array assay have not been previously reported. Therefore, the functions of the IE1-protein interactions need to be further explored in the future.
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Turnbull J, Tiberia E, Pereira S, Zhao X, Pencea N, Wheeler AL, Yu WQ, Ivovic A, Naranian T, Israelian N, Draginov A, Piliguian M, Frankland PW, Wang P, Ackerley CA, Giacca A, Minassian BA. Deficiency of a glycogen synthase-associated protein, Epm2aip1, causes decreased glycogen synthesis and hepatic insulin resistance. J Biol Chem 2013; 288:34627-37. [PMID: 24142699 DOI: 10.1074/jbc.m113.483198] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogen synthesis is a major component of the insulin response, and defective glycogen synthesis is a major portion of insulin resistance. Insulin regulates glycogen synthase (GS) through incompletely defined pathways that activate the enzyme through dephosphorylation and, more potently, allosteric activation. We identify Epm2aip1 as a GS-associated protein. We show that the absence of Epm2aip1 in mice impairs allosteric activation of GS by glucose 6-phosphate, decreases hepatic glycogen synthesis, increases liver fat, causes hepatic insulin resistance, and protects against age-related obesity. Our work identifies a novel GS-associated GS activity-modulating component of insulin resistance.
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29
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Hiong KC, Ip YK, Wong WP, Chew SF. Differential gene expression in the brain of the African lungfish, Protopterus annectens, after six days or six months of aestivation in air. PLoS One 2013; 8:e71205. [PMID: 23976998 PMCID: PMC3745453 DOI: 10.1371/journal.pone.0071205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 07/03/2013] [Indexed: 11/18/2022] Open
Abstract
The African lungfish, Protopterus annectens, can undergo aestivation during drought. Aestivation has three phases: induction, maintenance and arousal. The objective of this study was to examine the differential gene expression in the brain of P. annectens during the induction (6 days) and maintenance (6 months) phases of aestivation as compared with the freshwater control using suppression subtractive hybridization. During the induction phase of aestivation, the mRNA expression of prolactin (prl) and growth hormone were up-regulated in the brain of P. annectens, which indicate for the first time the possible induction role of these two hormones in aestivation. Also, the up-regulation of mRNA expression of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein γ polypeptide and the down-regulation of phosphatidylethanolamine binding protein, suggest that there could be a reduction in biological and neuronal activities in the brain. The mRNA expression of cold inducible RNA-binding protein and glucose regulated protein 58 were also up-regulated in the brain, probably to enhance their cytoprotective effects. Furthermore, the down-regulation of prothymosin α expression suggests that there could be a suppression of transcription and cell proliferation in preparation for the maintenance phase. In general, the induction phase appeared to be characterized by reduction in glycolytic capacity and metabolic activity, suppression of protein synthesis and degradation, and an increase in defense against ammonia toxicity. In contrast, there was a down-regulation in the mRNA expression of prl in the brain of P. annectens during the maintenance phase of aestivation. In addition, there could be an increase in oxidative defense capacity, and up-regulation of transcription, translation, and glycolytic capacities in preparation for arousal. Overall, our results signify the importance of reconstruction of protein structures and regulation of energy expenditure during the induction phase, and the needs to suppress protein degradation and conserve metabolic fuel stores during the maintenance phase of aestivation.
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Affiliation(s)
- Kum C. Hiong
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
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30
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Mohindra V, Tripathi RK, Singh RK, Lal KK. Molecular characterization and expression analysis of PPP1R3C in hypoxia-tolerant Indian catfish, Clarias batrachus (Linnaeus, 1758) under hypoxia. Gene 2013; 530:127-33. [PMID: 23948083 DOI: 10.1016/j.gene.2013.07.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 07/03/2013] [Accepted: 07/08/2013] [Indexed: 01/09/2023]
Abstract
Hypoxia is an important environmental stressor that leads to rapid adaptive changes in metabolic organization. However, the molecular mechanisms of hypoxia tolerance in fish remain largely unknown. The present work was focused on understanding the molecular mechanisms and signaling pathways that may lead to tolerance of Clarias batrachus to hypoxic stress. Protein phosphatase 1 regulatory subunit 3C (PPP1R3C) is a new hypoxia-inducible factor (HIF) targeted gene and is regulated by HIF-1 under hypoxic conditions. Overexpression of PPP1R3C increases glycogen accumulation through activation of several enzymes and processes. In this study, for the first time, full length cDNA of PPP1R3C from C. batrachus was characterized and its expression pattern in the brain, liver, muscle and spleen under short (progressive hypoxia; PH, 1h, 6h and 12h) and long-term (natural) hypoxic conditions was investigated. The complete cDNA of PPP1R3C was of 1499 bp, encoding 285 amino acid residues. The identified protein had a protein phosphatase 1 binding motif and a carbohydrate binding domain, thought to be involved in the regulation of glycogen metabolism. Short-term hypoxia exposure caused significant increase in PPP1R3C transcripts in the liver (6h; 6.96 fold and 12h; 3.91 fold) and muscle (progressive hypoxia; 3.46 fold), while, after long-term hypoxia exposure, significant up-regulation in the liver (7.77 fold) and spleen (6.59 fold) tissues was observed. No significant differences were observed in the brain for any time periods. Thus PPP1R3C may play an important role in the tolerance of C. batrachus to hypoxia.
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Affiliation(s)
- Vindhya Mohindra
- National Bureau of Fish Genetic Resources (ICAR), Canal Ring Road, P.O. Dilkusha, Lucknow 226002, UP, India.
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31
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Abstract
Manganese is an important metal for human health, being absolutely necessary for development, metabolism, and the antioxidant system. Nevertheless, excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and parkinsonian-like symptoms. Hence, Mn has a paradoxal effect in animals, a Janus-faced metal. Extensive work has been carried out to understand Mn-induced neurotoxicity and to find an effective treatment. This review focuses on the requirement for Mn in human health as well as the diseases associated with excessive exposure to this metal.
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Affiliation(s)
- Daiana Silva Avila
- Biochemistry Graduation Program, Universidade Federal do Pampa, Uruguaiana, Rio Grande do Sul, Brazil,
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32
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Zhang Y, Xu D, Huang H, Chen S, Wang L, Zhu L, Jiang X, Ruan X, Luo X, Cao P, Liu W, Pan Y, Wang Z, Chen Y. Regulation of glucose homeostasis and lipid metabolism by PPP1R3G-mediated hepatic glycogenesis. Mol Endocrinol 2013; 28:116-26. [PMID: 24264575 DOI: 10.1210/me.2013-1268] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Liver glycogen metabolism plays an important role in glucose homeostasis. Glycogen synthesis is mainly regulated by glycogen synthase that is dephosphorylated and activated by protein phosphatase 1 (PP1) in combination with glycogen-targeting subunits or G subunits. There are seven G subunits (PPP1R3A to G) that control glycogenesis in different organs. PPP1R3G is a recently discovered G subunit whose expression is changed along the fasting-feeding cycle and is proposed to play a role in postprandial glucose homeostasis. In this study, we analyzed the physiological function of PPP1R3G using a mouse model with liver-specific overexpression of PPP1R3G. PPP1R3G overexpression increases hepatic glycogen accumulation, stimulates glycogen synthase activity, elevates fasting blood glucose level, and accelerates postprandial blood glucose clearance. In addition, the transgenic mice have a reduced fat composition, together with decreased hepatic triglyceride level. Fasting-induced hepatic steatosis is relieved by PPP1R3G overexpression. In addition, PPP1R3G overexpression is able to elevate glycogenesis in primary hepatocytes. The glycogen-binding domain is indispensable for the physiological activities of PPP1R3G on glucose metabolism and triglyceride accumulation in the liver. Cumulatively, these data indicate that PPP1R3G plays a critical role in postprandial glucose homeostasis and liver triglyceride metabolism via its regulation on hepatic glycogenesis.
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Affiliation(s)
- Yongxian Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, China
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Bowman AB, Kwakye GF, Herrero Hernández E, Aschner M. Role of manganese in neurodegenerative diseases. J Trace Elem Med Biol 2011; 25:191-203. [PMID: 21963226 PMCID: PMC3230726 DOI: 10.1016/j.jtemb.2011.08.144] [Citation(s) in RCA: 238] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 08/16/2011] [Indexed: 12/17/2022]
Abstract
Manganese (Mn) is an essential ubiquitous trace element that is required for normal growth, development and cellular homeostasis. Exposure to high Mn levels causes a clinical disease characterized by extrapyramidal symptom resembling idiopathic Parkinson's disease (IPD). The present review focuses on the role of various transporters in maintaining brain Mn homeostasis along with recent methodological advances in real-time measurements of intracellular Mn levels. We also provide an overview on the role for Mn in IPD, discussing the similarities (and differences) between manganism and IPD, and the relationship between α-synuclein and Mn-related protein aggregation, as well as mitochondrial dysfunction, Mn and PD. Additional sections of the review discuss the link between Mn and Huntington's disease (HD), with emphasis on huntingtin function and the potential role for altered Mn homeostasis and toxicity in HD. We conclude with a brief survey on the potential role of Mn in the etiologies of Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and prion disease. Where possible, we discuss the mechanistic commonalities inherent to Mn-induced neurotoxicity and neurodegenerative disorders.
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Affiliation(s)
- Aaron B Bowman
- Department of Neurology, Vanderbilt Kennedy Center, Center for Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN 37232-8552, United States
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Puri R, Jain N, Ganesh S. Increased glucose concentration results in reduced proteasomal activity and the formation of glycogen positive aggresomal structures. FEBS J 2011; 278:3688-98. [PMID: 21815999 DOI: 10.1111/j.1742-4658.2011.08287.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent studies indicate that glycogen, besides being a principal storage product, confers protection against cellular stress through an unknown physiological pathway. Abnormal glycogen inclusions have also been considered to underlie pathology in a few neurodegenerative disorders that are caused by proteolytic dysfunctions, although a link between proteolytic pathways and glycogen accumulation is yet to be established. In the present study, we investigated the subcellular localization of glycogen particles and report that their distribution is altered under physiological stress. Using a cellular model, we show that glycogen particles are recruited to the centrosomal aggresomal structures upon proteasomal or lysosomal blockade, and that this recruitment is dependent on the microtubule function. We also show that an increase in the glucose concentration leads to decreased cellular proteasomal activity and the formation of glycogen positive aggresomal structures. Proteasomal blockade also leads to the formation of diastase-resistant polyglucosan bodies. The glycogen particles in aggresomes might provide energy to the proteolytic process and/or function as a scaffold. Taken together, the findings of the present study suggest a functional link between proteasomal function and polyglucosan bodies, and also suggest that these two physiological processes could be linked in neurodegenerative disorders.
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Affiliation(s)
- Rajat Puri
- Department of Biological Sciences and Bioengineering, India Institute of Technology, Kanpur, India
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Kelsall IR, Voss M, Munro S, Cuthbertson DJR, Cohen PTW. R3F, a novel membrane-associated glycogen targeting subunit of protein phosphatase 1 regulates glycogen synthase in astrocytoma cells in response to glucose and extracellular signals. J Neurochem 2011; 118:596-610. [DOI: 10.1111/j.1471-4159.2011.07345.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Guerrero R, Vernia S, Sanz R, Abreu-Rodríguez I, Almaraz C, García-Hoyos M, Michelucci R, Tassinari CA, Riguzzi P, Nobile C, Sanz P, Serratosa JM, Gómez-Garre P. A PTG variant contributes to a milder phenotype in Lafora disease. PLoS One 2011; 6:e21294. [PMID: 21738631 PMCID: PMC3127956 DOI: 10.1371/journal.pone.0021294] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 05/25/2011] [Indexed: 11/18/2022] Open
Abstract
Lafora disease is an autosomal recessive form of progressive myoclonus epilepsy with no effective therapy. Although the outcome is always unfavorable, onset of symptoms and progression of the disease may vary. We aimed to identify modifier genes that may contribute to the clinical course of Lafora disease patients with EPM2A or EPM2B mutations. We established a list of 43 genes coding for proteins related to laforin/malin function and/or glycogen metabolism and tested common polymorphisms for possible associations with phenotypic differences using a collection of Lafora disease families. Genotype and haplotype analysis showed that PPP1R3C may be associated with a slow progression of the disease. The PPP1R3C gene encodes protein targeting to glycogen (PTG). Glycogen targeting subunits play a major role in recruiting type 1 protein phosphatase (PP1) to glycogen-enriched cell compartments and in increasing the specific activity of PP1 toward specific glycogenic substrates (glycogen synthase and glycogen phosphorylase). Here, we report a new mutation (c.746A>G, N249S) in the PPP1R3C gene that results in a decreased capacity to induce glycogen synthesis and a reduced interaction with glycogen phosphorylase and laforin, supporting a key role of this mutation in the glycogenic activity of PTG. This variant was found in one of two affected siblings of a Lafora disease family characterized by a remarkable mild course. Our findings suggest that variations in PTG may condition the course of Lafora disease and establish PTG as a potential target for pharmacogenetic and therapeutic approaches.
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Affiliation(s)
- Rosa Guerrero
- Laboratorio de Neurología-Unidad de Epilepsia, Servicio de Neurología, Instituto Investigación Sanitaria Fundación Jiménez Díaz, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Santiago Vernia
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Raúl Sanz
- Laboratorio de Neurología-Unidad de Epilepsia, Servicio de Neurología, Instituto Investigación Sanitaria Fundación Jiménez Díaz, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Irene Abreu-Rodríguez
- Laboratorio de Investigaciones Biomédicas, Instituto de Biomedicina de Sevilla (IBiS), Sevilla, Spain
| | - Carmen Almaraz
- Laboratorio de Neurología-Unidad de Epilepsia, Servicio de Neurología, Instituto Investigación Sanitaria Fundación Jiménez Díaz, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - María García-Hoyos
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Roberto Michelucci
- Unit of Neurology, Department of Neurosciences, Bellaria Hospital, Bologna, Italy
| | | | - Patrizia Riguzzi
- Unit of Neurology, Department of Neurosciences, Bellaria Hospital, Bologna, Italy
| | - Carlo Nobile
- Section of Padua, CNR-Institute of Neurosciences, Padua, Italy
| | - Pascual Sanz
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
| | - José M. Serratosa
- Laboratorio de Neurología-Unidad de Epilepsia, Servicio de Neurología, Instituto Investigación Sanitaria Fundación Jiménez Díaz, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- * E-mail: (JMS); (PG-G)
| | - Pilar Gómez-Garre
- Laboratorio de Neurología-Unidad de Epilepsia, Servicio de Neurología, Instituto Investigación Sanitaria Fundación Jiménez Díaz, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- Unidad de Trastornos del Movimiento, Servicio de Neurología y Neurofisiología Clínica, Instituto de Biomedicina de Sevilla (IBiS), Sevilla, Spain
- * E-mail: (JMS); (PG-G)
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PTG depletion removes Lafora bodies and rescues the fatal epilepsy of Lafora disease. PLoS Genet 2011; 7:e1002037. [PMID: 21552327 PMCID: PMC3084203 DOI: 10.1371/journal.pgen.1002037] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 02/11/2011] [Indexed: 11/24/2022] Open
Abstract
Lafora disease is the most common teenage-onset neurodegenerative disease, the main teenage-onset form of progressive myoclonus epilepsy (PME), and one of the severest epilepsies. Pathologically, a starch-like compound, polyglucosan, accumulates in neuronal cell bodies and overtakes neuronal small processes, mainly dendrites. Polyglucosan formation is catalyzed by glycogen synthase, which is activated through dephosphorylation by glycogen-associated protein phosphatase-1 (PP1). Here we remove PTG, one of the proteins that target PP1 to glycogen, from mice with Lafora disease. This results in near-complete disappearance of polyglucosans and in resolution of neurodegeneration and myoclonic epilepsy. This work discloses an entryway to treating this fatal epilepsy and potentially other glycogen storage diseases. Lafora disease (LD) is a fatal epilepsy that afflicts previously normal teenagers. It is caused by mutations in the EPM2A or EPM2B genes encoding the laforin carbohydrate-binding phosphatase and the malin E3 ubiquitin ligase. LD is the most common neurodegenerative epilepsy of adolescents. Affected children suffer an ordeal lasting 10 years, consisting of escalating seizures, constant body jerking, particularly frightening epileptic visual hallucinations, and later on dementia. They die of massive convulsion. Brain biopsies reveal accumulation of a starch-like compound, polyglucosan, overtaking dendrites and likely causing the disease, and neurodegeneration. Glycogen synthase (GS), the enzyme that forms normal glycogen, is also responsible for synthesizing these polyglucosans. We reasoned that reducing GS activity might prevent polyglucosan formation. Mice deficient of Epm2a replicate LD and are a standard model. Members of our group generated mice deficient of PTG, a protein involved in activating GS. By breeding LD mice with PTG-lacking mice, we generated LD mice lacking the GS-activating effect of PTG. This resulted in a cure. The double knockout mice have almost no polyglucosan, no neurodegeneration, and no seizures. Our work opens an avenue of treatment for this fatal epilepsy, which may also be applicable to other glycogen storage diseases.
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Karthik D, Ravikumar S. Characterization of the brain proteome of rats with diabetes mellitus through two-dimensional electrophoresis and mass spectrometry. Brain Res 2011; 1371:171-9. [DOI: 10.1016/j.brainres.2010.11.066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 11/18/2010] [Indexed: 01/28/2023]
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Shen GM, Zhang FL, Liu XL, Zhang JW. Hypoxia-inducible factor 1-mediated regulation of PPP1R3C promotes glycogen accumulation in human MCF-7 cells under hypoxia. FEBS Lett 2010; 584:4366-72. [PMID: 20888814 DOI: 10.1016/j.febslet.2010.09.040] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 09/10/2010] [Accepted: 09/24/2010] [Indexed: 12/11/2022]
Abstract
Hundreds of genes can be regulated by hypoxia-inducible factor 1 (HIF1) under hypoxia. Here we demonstrated a HIF1-mediated induction of protein phosphatase 1, regulatory subunit 3C gene (PPP1R3C) in human MCF7 cells under hypoxia. By mutation analysis we confirmed the presence of a functional hypoxia response element that is located 229bp upstream from the PPP1R3C gene. PPP1R3C induction correlates with a significant glycogen accumulation in MCF7 cells under hypoxia. Knockdown of either HIF1α or PPP1R3C attenuated hypoxia-induced glycogen accumulation significantly. Knockdown of HIF2α reduced hypoxia-induced glycogen accumulation slightly (but not significantly). Our results demonstrated that HIF1 promotes glycogen accumulation through regulating PPP1R3C expression under hypoxia, which revealed a novel metabolic adaptation of cells to hypoxia.
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Affiliation(s)
- Guo-Min Shen
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Jurczak MJ, Zapater JL, Greenberg CC, Brady MJ. Generation of a dominant-negative glycogen targeting subunit for protein phosphatase-1. Obesity (Silver Spring) 2010; 18:1881-7. [PMID: 20203631 DOI: 10.1038/oby.2010.32] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Modulation of the expression of the protein phosphatase-1 (PP1) glycogen-targeting subunit PTG exerts profound effects on cellular glycogen metabolism in vitro and in vivo. PTG contains three distinct binding domains for glycogen, PP1, and a common site for glycogen synthase and phosphorylase. The impact of disrupting the PP1-binding domain on PTG function was examined in 3T3-L1 adipocytes. A full-length PTG mutant was generated as an adenoviral construct in which the valine and phenylalanine residues in the conserved PP1-binding domain were mutated to alanine (PTG-VF). Infection of fully differentiated 3T3-L1 adipocytes with the PTG-VF adenovirus reduced glycogen stores by over 50%. In vitro, PTG-VF competitively interfered with wild-type PTG action, suggesting that the mutant construct acted as a dominant-negative molecule. The reduction in cellular glycogen storage was due to a significantly increased rate of glycogen turnover. Interestingly, acute basal and insulin-stimulated glucose uptake and glycogen synthesis rates were enhanced in PTG-VF expressing cells vs. control 3T3-L1 adipocytes, likely as a compensatory response to the loss of glycogen stores. These results indicate that the mutation of the PP1-binding domain on PTG resulted in the generation of a dominant-negative molecule that impeded endogenous PTG action and reduced cellular glycogen levels, through enhancement of glycogenolysis rather than impairment of glycogen synthesis.
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Affiliation(s)
- Michael J Jurczak
- Department of Medicine, Section of Endocrinology, Diabetes, and Metabolism and the Committee on Molecular Metabolism and Nutrition, The University of Chicago, Chicago, Illinois, USA
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Ezra DG, Ellis JS, Beaconsfield M, Collin R, Bailly M. Changes in fibroblast mechanostat set point and mechanosensitivity: an adaptive response to mechanical stress in floppy eyelid syndrome. Invest Ophthalmol Vis Sci 2010; 51:3853-63. [PMID: 20220050 PMCID: PMC2910631 DOI: 10.1167/iovs.09-4724] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 02/04/2010] [Accepted: 02/05/2010] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Floppy eyelid syndrome (FES) is an acquired hyperelasticity disorder affecting the upper eyelid. The tarsal plate becomes hyperelastic with a loss of intrinsic rigidity. As a result, the eyelid is subjected to cyclic mechanical stress. This condition was used as a model to investigate changes in dynamic fibroblast contractility in the context of chronic cyclic mechanical stress. METHODS Contractile efficiency was investigated in a free-floating, three-dimensional collagen matrix model. Intrinsic cellular force measurements and responses to changes in gel tension were explored using a tensioning culture force monitor (t-CFM). Gene expression differences between cell lines exhibiting differences in contractile phenotype were explored with a genome level microarray platform and RT-PCR. RESULTS FES tarsal plate fibroblasts (TFs) showed an increased contractile efficiency compared with the control, and t-CFM measurements confirmed a higher intrinsic cellular force at plateau levels. Cyclic stretch/relaxation experiments determined that TFs in FES maintained a functional tensional homeostasis response but with an altered sensitivity, operating around a higher mechanostat set point. Gene expression array and RT-PCR analysis identified V-CAM1 and PPP1R3C as being upregulated in FES TFs. CONCLUSIONS These changes may represent an adaptive response that allows tensional homeostasis to be maintained at the high levels of tissue stress experienced in FES. Gene expression studies point to a role for V-CAM1 and PPP1R3C in mediating changes in the dynamic range of mechanosensitivity of TFs. This work identifies FES as a useful model for the study of adaptive physiological responses to mechanical stress.
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Affiliation(s)
- Daniel G Ezra
- National Institute of Health Research Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.
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Petit JM, Tobler I, Kopp C, Morgenthaler F, Borbély AA, Magistretti PJ. Metabolic response of the cerebral cortex following gentle sleep deprivation and modafinil administration. Sleep 2010; 33:901-8. [PMID: 20614850 DOI: 10.1093/sleep/33.7.901] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
STUDY OBJECTIVES The main energy reserve of the brain is glycogen, which is almost exclusively localized in astrocytes. We previously reported that cerebral expression of certain genes related to glycogen metabolism changed following instrumental sleep deprivation in mice. Here, we extended our investigations to another set of genes related to glycogen and glucose metabolism. We also compared the effect of instrumentally and pharmacologically induced prolonged wakefulness, followed (or not) by 3 hours of sleep recovery, on the expression of genes related to brain energy metabolism. DESIGN Sleep deprivation for 6-7 hours. SETTING Animal sleep research laboratory. PARTICIPANTS Adults OF1 mice. INTERVENTIONS Wakefulness was maintained by "gentle sleep deprivation" method (GSD) or by administration of the wakefulness-promoting drug modafinil (MOD) (200 mg/kg i.p.). MEASUREMENTS AND RESULTS Levels of mRNAs encoding proteins related to energy metabolism were measured by quantitative real-time PCR in the cerebral cortex. The mRNAs encoding protein targeting to glycogen (PTG) and the glial glucose transporter were significantly increased following both procedures used to prolong wakefulness. Glycogenin mRNA levels were increased only after GSD, while neuronal glucose transporter mRNA only after MOD. These effects were reversed after sleep recovery. A significant enhancement of glycogen synthase activity without any changes in glycogen levels was observed in both conditions. CONCLUSIONS These results indicate the existence of a metabolic adaptation of astrocytes aimed at maintaining brain energy homeostasis during the sleep-wake cycle.
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Affiliation(s)
- Jean-Marie Petit
- Laboratory of Neuroenergetic and Cellular Dynamics, Brain Mind Institute, Life Science Faculty, EPFL, Lausanne, Switzerland.
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Stapleton D, Nelson C, Parsawar K, McClain D, Gilbert-Wilson R, Barker E, Rudd B, Brown K, Hendrix W, O’Donnell P, Parker G. Analysis of hepatic glycogen-associated proteins. Proteomics 2010; 10:2320-9. [PMID: 20391537 PMCID: PMC2892038 DOI: 10.1002/pmic.200900628] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Accepted: 03/24/2010] [Indexed: 12/25/2022]
Abstract
Glycogen particles are associated with a population of proteins that mediate its biological functions, including: management of glucose flux into and out of the glycogen particle, maintenance of glycogen structure and regulation of particle size, number, and cellular location. A survey of the glycogen-associated proteome would be predicted to identify the relative representation of known members of this population, and associations with unexpected proteins that have the potential to mediate other functions of the glycogen particle. We therefore purified glycogen particles from both mouse and rat liver, using different techniques, and analyzed the resulting tryptic peptides by MS. We also specifically eluted glycogen-binding proteins from the pellet using malto-oligosaccharides. Comparison of the rat and mouse populations, and analysis of specifically eluted proteins allow some conclusions to be made about the hepatic glycogen sub-proteome. With the exception of glycogen branching enzyme all glycogen metabolic proteins were detected. Novel associations were identified, including ferritin and starch-binding domain protein 1, a protein that contains both a transmembrane endoplasmic reticulum signal peptide and a carbohydrate-binding module. This study therefore provides insight into the organization of the glycogen proteome, identifies other associated proteins and provides a starting point to explore the dynamic nature and cellular distribution of this metabolically important protein population.
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Affiliation(s)
- David Stapleton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Chad Nelson
- University of Utah, Mass Spectrometry and Proteomics Core Facility, University of Utah, Salt Lake City, Utah, 84132, USA
| | - Krishna Parsawar
- University of Utah, Mass Spectrometry and Proteomics Core Facility, University of Utah, Salt Lake City, Utah, 84132, USA
| | - Donald McClain
- Department of Medicine, Division of Endocrinology, University of Utah School of Medicine, Salt Lake City, Utah, 84132, USA
| | - Ryan Gilbert-Wilson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Elizabeth Barker
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Brant Rudd
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Kevin Brown
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Wayne Hendrix
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
| | - Paul O’Donnell
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Glendon Parker
- Department of Medicine, Division of Endocrinology, University of Utah School of Medicine, Salt Lake City, Utah, 84132, USA
- Department of Biology, College of Science and Health, Utah Valley University, Orem, Utah, 84058, USA
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Markan KR, Jurczak MJ, Brady MJ. Stranger in a strange land: roles of glycogen turnover in adipose tissue metabolism. Mol Cell Endocrinol 2010; 318:54-60. [PMID: 19703517 PMCID: PMC2826604 DOI: 10.1016/j.mce.2009.08.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/14/2009] [Accepted: 08/16/2009] [Indexed: 01/03/2023]
Abstract
Triglyceride storage in adipose tissue comprises the principal energy reserve in mammals. Additionally glucose can be stored as glycogen in the fed state, primarily in liver and skeletal muscle, for mobilization during times of energy deficit. Adipose tissue also contains glycogen stores albeit at very low levels. The physiological role of glycogen metabolism in adipocytes remains unclear. However, both classical literature and more recent work demonstrate that the dynamic regulation of adipose glycogen may serve as an energy sensing modality in the coordination of glucose and lipid metabolism in adipose tissue, especially during the fasted to fed transition.
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Affiliation(s)
- Kathleen R. Markan
- Department of Medicine, Section of Endocrinology, Diabetes and Metabolism and the Committee on Molecular Metabolism and Nutrition, 5841 South Maryland Avenue, The University of Chicago, Chicago, Illinois 60637, USA
| | - Michael J. Jurczak
- Department of Internal Medicine, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06-536-8012, USA
| | - Matthew J. Brady
- Department of Medicine, Section of Endocrinology, Diabetes and Metabolism and the Committee on Molecular Metabolism and Nutrition, 5841 South Maryland Avenue, The University of Chicago, Chicago, Illinois 60637, USA
- Corresponding author at: Department of Medicine, Section of Adult and Pediatric, Endocrinology, Diabetes, & Metabolism, The University of Chicago, 5841 South, Maryland Avenue, MC 1027, Chicago, IL 60637 USA., Tel.: 773-702-2346; fax: 773-834-0486., (M. Brady)
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Danos AM, Osmanovic S, Brady MJ. Differential regulation of glycogenolysis by mutant protein phosphatase-1 glycogen-targeting subunits. J Biol Chem 2009; 284:19544-53. [PMID: 19487702 DOI: 10.1074/jbc.m109.015073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PTG and G(L) are hepatic protein phosphatase-1 (PP1) glycogen-targeting subunits, which direct PP1 activity against glycogen synthase (GS) and/or phosphorylase (GP). The C-terminal 16 amino residues of G(L) comprise a high affinity binding site for GP that regulates bound PP1 activity against GS. In this study, a truncated G(L) construct lacking the GP-binding site (G(L)tr) and a chimeric PTG molecule containing the C-terminal site (PTG-G(L)) were generated. As expected, GP binding to glutathione S-transferase (GST)-G(L)tr was reduced, whereas GP binding to GST-PTG-G(L) was increased 2- to 3-fold versus GST-PTG. In contrast, PP1 binding to all proteins was equivalent. Primary mouse hepatocytes were infected with adenoviral constructs for each subunit, and their effects on glycogen metabolism were investigated. G(L)tr expression was more effective at promoting GP inactivation, GS activation, and glycogen accumulation than G(L). Removal of the regulatory GP-binding site from G(L)tr completely blocked the inactivation of GS seen in G(L)-expressing cells following a drop in extracellular glucose. As a result, G(L)tr expression prevented glycogen mobilization under 5 mm glucose conditions. In contrast, equivalent overexpression of PTG or PTG-G(L) caused a similar increase in glycogen-targeted PP1 levels and GS dephosphorylation. Surprisingly, GP dephosphorylation was significantly reduced in PTG-G(L)-overexpressing cells. As a result, PTG-G(L) expression permitted glycogenolysis under 5 mm glucose conditions that was prevented in PTG-expressing cells. Thus, expression of constructs that contained the high affinity GP-binding site (G(L) and PTG-G(L)) displayed reduced glycogen accumulation and enhanced glycogenolysis compared with their respective controls, albeit via different mechanisms.
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Affiliation(s)
- Arpad M Danos
- Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois 60637, USA
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Boulatnikov IG, Nadeau OW, Daniels PJ, Sage JM, Jeyasingham MD, Villar MT, Artigues A, Carlson GM. The regulatory beta subunit of phosphorylase kinase interacts with glyceraldehyde-3-phosphate dehydrogenase. Biochemistry 2008; 47:7228-36. [PMID: 18549242 DOI: 10.1021/bi800681g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Skeletal muscle phosphorylase kinase (PhK) is an (alphabetagammadelta) 4 hetero-oligomeric enzyme complex that phosphorylates and activates glycogen phosphorylase b (GP b) in a Ca (2+)-dependent reaction that couples muscle contraction with glycogen breakdown. GP b is PhK's only known in vivo substrate; however, given the great size and multiple subunits of the PhK complex, we screened muscle extracts for other potential targets. Extracts of P/J (control) and I/lnJ (PhK deficient) mice were incubated with [gamma- (32)P]ATP with or without Ca (2+) and compared to identify potential substrates. Candidate targets were resolved by two-dimensional polyacrylamide gel electrophoresis, and phosphorylated glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was identified by matrix-assisted laser desorption ionization mass spectroscopy. In vitro studies showed GAPDH to be a Ca (2+)-dependent substrate of PhK, although the rate of phosphorylation is very slow. GAPDH does, however, bind tightly to PhK, inhibiting at low concentrations (IC 50 approximately 0.45 microM) PhK's conversion of GP b. When a short synthetic peptide substrate was substituted for GP b, the inhibition was negligible, suggesting that GAPDH may inhibit predominantly by binding to the PhK complex at a locus distinct from its active site on the gamma subunit. To test this notion, the PhK-GAPDH complex was incubated with a chemical cross-linker, and a dimer between the regulatory beta subunit of PhK and GAPDH was formed. This interaction was confirmed by the fact that a subcomplex of PhK missing the beta subunit, specifically an alphagammadelta subcomplex, was unable to phosphorylate GAPDH, even though it is catalytically active toward GP b. Moreover, GAPDH had no effect on the conversion of GP b by the alphagammadelta subcomplex. The interactions described herein between the beta subunit of PhK and GAPDH provide a possible mechanism for the direct linkage of glycogenolysis and glycolysis in skeletal muscle.
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Affiliation(s)
- Igor G Boulatnikov
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Worby CA, Gentry MS, Dixon JE. Malin decreases glycogen accumulation by promoting the degradation of protein targeting to glycogen (PTG). J Biol Chem 2008; 283:4069-76. [PMID: 18070875 PMCID: PMC2251628 DOI: 10.1074/jbc.m708712200] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Lafora disease (LD) is an autosomal recessive neurodegenerative disease that results in progressive myoclonus epilepsy and death. LD is caused by mutations in either the E3 ubiquitin ligase malin or the dual specificity phosphatase laforin. A hallmark of LD is the accumulation of insoluble glycogen in the cytoplasm of cells from most tissues. Glycogen metabolism is regulated by phosphorylation of key metabolic enzymes. One regulator of this phosphorylation is protein targeting to glycogen (PTG/R5), a scaffold protein that binds both glycogen and many of the enzymes involved in glycogen synthesis, including protein phosphatase 1 (PP1), glycogen synthase, phosphorylase, and laforin. Overexpression of PTG markedly increases glycogen accumulation, and decreased PTG expression decreases glycogen stores. To investigate if malin and laforin play a role in glycogen metabolism, we overexpressed PTG, malin, and laforin in tissue culture cells. We found that expression of malin or laforin decreased PTG-stimulated glycogen accumulation by 25%, and co-expression of malin and laforin abolished PTG-stimulated glycogen accumulation. Consistent with this result, we found that malin ubiquitinates PTG in a laforin-dependent manner, both in vivo and in vitro, and targets PTG for proteasome-dependent degradation. These results suggest an additional mechanism, involving laforin and malin, in regulating glycogen metabolism.
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Affiliation(s)
- Carolyn A Worby
- Department of Pharmacology, University of California at San Diego, La Jolla, California 92093-0721, USA
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Solaz-Fuster MC, Gimeno-Alcañiz JV, Ros S, Fernandez-Sanchez ME, Garcia-Fojeda B, Garcia OC, Vilchez D, Dominguez J, Garcia-Rocha M, Sanchez-Piris M, Aguado C, Knecht E, Serratosa J, Guinovart JJ, Sanz P, de Córdoba SR. Regulation of glycogen synthesis by the laforin–malin complex is modulated by the AMP-activated protein kinase pathway. Hum Mol Genet 2007; 17:667-78. [DOI: 10.1093/hmg/ddm339] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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49
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Mechanism suppressing glycogen synthesis in neurons and its demise in progressive myoclonus epilepsy. Nat Neurosci 2007; 10:1407-13. [PMID: 17952067 DOI: 10.1038/nn1998] [Citation(s) in RCA: 266] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 09/21/2007] [Indexed: 11/08/2022]
Abstract
Glycogen synthesis is normally absent in neurons. However, inclusion bodies resembling abnormal glycogen accumulate in several neurological diseases, particularly in progressive myoclonus epilepsy or Lafora disease. We show here that mouse neurons have the enzymatic machinery for synthesizing glycogen, but that it is suppressed by retention of muscle glycogen synthase (MGS) in the phosphorylated, inactive state. This suppression was further ensured by a complex of laforin and malin, which are the two proteins whose mutations cause Lafora disease. The laforin-malin complex caused proteasome-dependent degradation both of the adaptor protein targeting to glycogen, PTG, which brings protein phosphatase 1 to MGS for activation, and of MGS itself. Enforced expression of PTG led to glycogen deposition in neurons and caused apoptosis. Therefore, the malin-laforin complex ensures a blockade of neuronal glycogen synthesis even under intense glycogenic conditions. Here we explain the formation of polyglucosan inclusions in Lafora disease by demonstrating a crucial role for laforin and malin in glycogen synthesis.
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50
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Winter SL, Bosnoyan-Collins L, Pinnaduwage D, Andrulis IL. The interaction of PP1 with BRCA1 and analysis of their expression in breast tumors. BMC Cancer 2007; 7:85. [PMID: 17511879 PMCID: PMC1906825 DOI: 10.1186/1471-2407-7-85] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Accepted: 05/19/2007] [Indexed: 11/18/2022] Open
Abstract
Background The breast cancer susceptibility gene, BRCA1, is implicated in multiple cellular processes including DNA repair, the transactivation of genes, and the ubiquitination of proteins; however its precise functions remain to be fully understood. Identification and characterization of BRCA1 protein interactions may help to further elucidate the function and regulation of BRCA1. Additionally, detection of changes in the expression levels of BRCA1 and its interacting proteins in primary human breast tumors may further illuminate their role in the development of breast cancer. Methods We performed a yeast two-hybrid study to identify proteins that interact with exon11 of BRCA1 and identified Protein Phosphatase 1β (PP1β), an isoform of the serine threonine phosphatase, PP1. GST-pull down and co-immunoprecipitation assays were performed to further characterize this interaction. Additionally, Real-Time PCR was utilized to determine the expression of BRCA1, PP1α, β and γ in primary human breast tumors and normal breast tissue to identify alterations in the expression of these genes in breast cancer. Results PP1 and BRCA1 co-immunoprecipitate and the region within BRCA1 as well as the specific PP1 interacting domain mediating this interaction were identified. Following mRNA expression analysis, we identified low levels of BRCA1 and variable levels of PP1α and β in primary sporadic human breast tumors. Furthermore, BRCA1, PP1β and PP1γ were significantly higher in normal tissue specimens (BRCA1 p = 0.01, PP1β: p = 0.03, PP1γ, p = 1.9 × 10-6) compared to sporadic breast tumor samples. Interestingly, we also identified that ER negative tumors are associated with low levels of PP1α expression. Conclusion The identification and characterization of the interaction of BRCA1 with PP1 and detection of changes in the expression of PP1 and genes encoding other BRCA1 associated proteins identifies important genetic pathways that may be significant to breast tumorigenesis. Alterations in the expression of genes, particularly phosphatases that operate in association with BRCA1, could negatively affect the function of BRCA1 or BRCA1 associated proteins, contributing to the development of breast cancer.
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Affiliation(s)
- Sherry L Winter
- Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Lucine Bosnoyan-Collins
- Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Dushanthi Pinnaduwage
- Division of Epidemiology and Biostatistics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Irene L Andrulis
- Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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