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Eskandari F, Salimi M, Binayi F, Abdollahifar MA, Eftekhary M, Hedayati M, Ghanbarian H, Zardooz H. Investigating the Effects of Maternal Separation on Hypothalamic-Pituitary-Adrenal Axis and Glucose Homeostasis under Chronic Social Defeat Stress in Young Adult Male Rat Offspring. Neuroendocrinology 2022; 113:361-380. [PMID: 36088912 DOI: 10.1159/000526989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 09/05/2022] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Given the suggested metabolic regulatory effects of stress-responsive genes and based on the impacts of early-life stress on HPA axis development, this study aimed to characterize the maternal separation (MS) impact on the communication between glucose metabolism and HPA axis dysregulations under chronic social defeat stress (CSDS). METHODS During the first 2 weeks of life, male Wistar rats were either exposed to MS or left undisturbed with their mothers (Std). Starting on postnatal day 50, the animals of each group were either left undisturbed in the standard group housing (Con) or underwent CSDS for 3 weeks. There were four groups (n = 10/group): Std-Con, MS-Con, Std-CSDS, and MS-CSDS. RESULTS Early and/or adult life adversity reduced β-cell number, muscular FK506-binding protein 51 (FKBP51) content, and BMI in adulthood. The reduction of β-cell number and BMI in the MS-CSDS rats were more profound than MS-Con group. CSDS either alone or in combination with MS reduced locomotor activity and increased and decreased corticotropin-releasing factor type 1 receptor (CRFR1) content, respectively, in hypothalamus and pancreas. Although, under CSDS, MS intensified HPA axis overactivity and reduced isolated islets' insulin secretion, it could promote resilience to depression symptoms. No differences were observed in hypothalamic Fkbp5 gene DNA methylation and glucose tolerance among groups. CONCLUSION MS exacerbated HPA axis overactivity and the endocrine pancreas dysfunctions under CSDS. The intensified corticosterone secretion and the diminished content of pancreatic CRFR1 protein could be involved in the reduced β-cell number and islets' insulin secretion under CSDS. The decreased muscular FKBP51 content might be a homeostatic response to slow down insulin resistance development under chronic stress.
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Affiliation(s)
- Farzaneh Eskandari
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mina Salimi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fateme Binayi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad-Amin Abdollahifar
- Department of Biology and Anatomical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohamad Eftekhary
- Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehdi Hedayati
- Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Ghanbarian
- Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Homeira Zardooz
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Manning AK, Goustin AS, Kleinbrink EL, Thepsuwan P, Cai J, Ju D, Leong A, Udler MS, Brown JB, Goodarzi MO, Rotter JI, Sladek R, Meigs JB, Lipovich L. A Long Non-coding RNA, LOC157273, Is an Effector Transcript at the Chromosome 8p23.1- PPP1R3B Metabolic Traits and Type 2 Diabetes Risk Locus. Front Genet 2020; 11:615. [PMID: 32754192 PMCID: PMC7367044 DOI: 10.3389/fgene.2020.00615] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 05/20/2020] [Indexed: 01/08/2023] Open
Abstract
AIMS Causal transcripts at genomic loci associated with type 2 diabetes (T2D) are mostly unknown. The chr8p23.1 variant rs4841132, associated with an insulin-resistant diabetes risk phenotype, lies in the second exon of a long non-coding RNA (lncRNA) gene, LOC157273, located 175 kilobases from PPP1R3B, which encodes a key protein regulating insulin-mediated hepatic glycogen storage in humans. We hypothesized that LOC157273 regulates expression of PPP1R3B in human hepatocytes. METHODS We tested our hypothesis using Stellaris fluorescent in situ hybridization to assess subcellular localization of LOC157273; small interfering RNA (siRNA) knockdown of LOC157273, followed by RT-PCR to quantify LOC157273 and PPP1R3B expression; RNA-seq to quantify the whole-transcriptome gene expression response to LOC157273 knockdown; and an insulin-stimulated assay to measure hepatocyte glycogen deposition before and after knockdown. RESULTS We found that siRNA knockdown decreased LOC157273 transcript levels by approximately 80%, increased PPP1R3B mRNA levels by 1.7-fold, and increased glycogen deposition by >50% in primary human hepatocytes. An A/G heterozygous carrier (vs. three G/G carriers) had reduced LOC157273 abundance due to reduced transcription of the A allele and increased PPP1R3B expression and glycogen deposition. CONCLUSION We show that the lncRNA LOC157273 is a negative regulator of PPP1R3B expression and glycogen deposition in human hepatocytes and a causal transcript at an insulin-resistant T2D risk locus.
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Affiliation(s)
- Alisa K. Manning
- Clinical and Translational Epidemiology Unit, Mongan Institute, Massachusetts General Hospital, Boston, MA, United States
- Department of Medicine, Harvard Medical School, Boston, MA, United States
- Programs in Metabolism and Medical & Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - Anton Scott Goustin
- Center for Molecular Medicine & Genetics, Wayne State University, Detroit, MI, United States
| | - Erica L. Kleinbrink
- Center for Molecular Medicine & Genetics, Wayne State University, Detroit, MI, United States
| | - Pattaraporn Thepsuwan
- Center for Molecular Medicine & Genetics, Wayne State University, Detroit, MI, United States
| | - Juan Cai
- Center for Molecular Medicine & Genetics, Wayne State University, Detroit, MI, United States
| | - Donghong Ju
- Center for Molecular Medicine & Genetics, Wayne State University, Detroit, MI, United States
- Karmanos Cancer Institute at Wayne State University, Detroit, MI, United States
| | - Aaron Leong
- Programs in Metabolism and Medical & Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, United States
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, United States
- Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, United States
| | - Miriam S. Udler
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, United States
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, United States
| | - James Bentley Brown
- Department of Statistics, University of California, Berkeley, Berkeley, CA, United States
- Centre for Computational Biology, University of Birmingham, Birmingham, United Kingdom
- Computational Biosciences Group, Biosciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Mark O. Goodarzi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Jerome I. Rotter
- The Institute for Translational Genomics and Population Sciences, Department of Pediatrics, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Robert Sladek
- Department of Human Genetics, McGill University, Montréal, QC, Canada
- Department of Medicine, McGill University, Montréal, QC, Canada
- McGill University and Genome Québec Innovation Centre, Montréal, QC, Canada
| | - James B. Meigs
- Department of Medicine, Harvard Medical School, Boston, MA, United States
- Programs in Metabolism and Medical & Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, United States
- Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, United States
| | - Leonard Lipovich
- Center for Molecular Medicine & Genetics, Wayne State University, Detroit, MI, United States
- Department of Neurology, School of Medicine, Wayne State University, Detroit, MI, United States
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3
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Cortes-Selva D, Elvington AF, Ready A, Rajwa B, Pearce EJ, Randolph GJ, Fairfax KC. Schistosoma mansoni Infection-Induced Transcriptional Changes in Hepatic Macrophage Metabolism Correlate With an Athero-Protective Phenotype. Front Immunol 2018; 9:2580. [PMID: 30483256 PMCID: PMC6240656 DOI: 10.3389/fimmu.2018.02580] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/19/2018] [Indexed: 01/22/2023] Open
Abstract
Hepatic macrophages play an essential role in the granulomatous response to infection with the parasitic helminth Schistosoma mansoni, but the transcriptional changes that underlie this effect are poorly understood. To explore this, we sorted the two previously recognized hepatic macrophage populations (perivascular and Kupffer cells) from naïve and S. mansoni-infected male mice and performed microarray analysis as part of the Immunological Genome Project. The two hepatic macrophage populations exhibited remarkably different genomic profiles. However, this diversity was substantially reduced following infection with S. mansoni, and in fact, both populations demonstrated increases in transcripts of the monocyte lineage, suggesting that both populations may be replenished by monocytes following infection. Pathway analysis showed a profound alteration in global metabolic pathways, including changes to phospholipid and cholesterol metabolism, as well as amino acid biosynthesis and glucagon signaling. These changes suggest a possible mechanism for the previously reported athero-protective effects of S. mansoni infection. Indeed, we find that male ApoE null mice fed a high-fat diet in combination with S. mansoni infection have reduced plaque area and increased glucose tolerance as compared to control mice. Transcript analysis of infected and control high-fat diet fed ApoE−/− mice confirm that ApoC1, Psat1, and Gys1 are all altered by infection, suggesting that altered hepatic macrophage metabolism is associated with S. mansoni- induced protection from hyperlipidemia, atherosclerosis, and glucose intolerance. These results suggest a previously unknown and unreported role of hepatic macrophages in the modulation of whole body lipid and glucose metabolism during infection and provide a template for examining the role of immunomodulation on the long-term metabolism of the host.
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Affiliation(s)
- Diana Cortes-Selva
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States
| | - Andrew F Elvington
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, United States.,Division of Health and Sport Sciences, Missouri Baptist University, St. Louis, MO, United States
| | - Andrew Ready
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States
| | - Bartek Rajwa
- Department of Basic Medical Sciences, Bindley Bioscience Center, College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States
| | - Edward J Pearce
- Department of Immunometabolism, Faculty of Biology, Max Planck Institute of Immunobiology and Epigenetics, University of Freiburg, Freiburg, Germany
| | - Gwendalyn J Randolph
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, United States
| | - Keke C Fairfax
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States.,Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, United States
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4
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Stender S, Smagris E, Lauridsen BK, Kofoed KF, Nordestgaard BG, Tybjærg-Hansen A, Pennacchio LA, Dickel DE, Cohen JC, Hobbs HH. Relationship between genetic variation at PPP1R3B and levels of liver glycogen and triglyceride. Hepatology 2018; 67:2182-2195. [PMID: 29266543 PMCID: PMC5991995 DOI: 10.1002/hep.29751] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/31/2017] [Accepted: 12/18/2017] [Indexed: 12/15/2022]
Abstract
UNLABELLED Genetic variation at rs4240624 on chromosome 8 is associated with an attenuated signal on hepatic computerized tomography, which has been attributed to changes in hepatic fat. The closest coding gene to rs4240624, PPP1R3B, encodes a protein that promotes hepatic glycogen synthesis. Here, we performed studies to determine whether the x-ray attenuation associated with rs4240624 is due to differences in hepatic glycogen or hepatic triglyceride content (HTGC). A sequence variant in complete linkage disequilibrium with rs4240624, rs4841132, was genotyped in the Dallas Heart Study (DHS), the Dallas Liver Study, and the Copenhagen Cohort (n = 112,428) of whom 1,539 had nonviral liver disease. The minor A-allele of rs4841132 was associated with increased hepatic x-ray attenuation (n = 1,572; P = 4 × 10-5 ), but not with HTGC (n = 2,674; P = 0.58). Rs4841132-A was associated with modest, but significant, elevations in serum alanine aminotransferase (ALT) in the Copenhagen Cohort (P = 3 × 10-4 ) and the DHS (P = 0.004), and with odds ratios for liver disease of 1.13 (95% CI, 0.97-1.31) and 1.23 (1.01-1.51), respectively. Mice lacking protein phosphatase 1 regulatory subunit 3B (PPP1R3B) were deficient in hepatic glycogen, whereas HTGC was unchanged. Hepatic overexpression of PPP1R3B caused accumulation of hepatic glycogen and elevated plasma levels of ALT, but did not change HTGC. CONCLUSION These observations are consistent with the notion that the minor allele of rs4841132 promotes a mild form of hepatic glycogenosis that is associated with hepatic injury. (Hepatology 2018;67:2182-2195).
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Affiliation(s)
- Stefan Stender
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390,Department of McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Eriks Smagris
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Bo K. Lauridsen
- Department of Clinical Biochemistry, Copenhagen University Hospital, Copenhagen University Hospital, Copenhagen, DK
| | - Klaus F. Kofoed
- Department of Cardiology and Radiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen University Hospital, Copenhagen, DK
| | - Børge G. Nordestgaard
- Department of Clinical Biochemistry and Copenhagen General Population Study, Herlev and Gentofte Hospital, Copenhagen University Hospital, Copenhagen University Hospital, Copenhagen, DK,The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen University Hospital, Copenhagen, DK
| | - Anne Tybjærg-Hansen
- Department of Clinical Biochemistry, Copenhagen University Hospital, Copenhagen University Hospital, Copenhagen, DK,Department of Clinical Biochemistry and Copenhagen General Population Study, Herlev and Gentofte Hospital, Copenhagen University Hospital, Copenhagen University Hospital, Copenhagen, DK,The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen University Hospital, Copenhagen, DK
| | | | | | - Jonathan C. Cohen
- Department of McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Helen H. Hobbs
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390,Department of McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390
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López-Soldado I, Zafra D, Duran J, Adrover A, Calbó J, Guinovart JJ. Liver glycogen reduces food intake and attenuates obesity in a high-fat diet-fed mouse model. Diabetes 2015; 64:796-807. [PMID: 25277398 DOI: 10.2337/db14-0728] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We generated mice that overexpress protein targeting to glycogen (PTG) in the liver (PTG(OE)), which results in an increase in liver glycogen. When fed a high-fat diet (HFD), these animals reduced their food intake. The resulting effect was a lower body weight, decreased fat mass, and reduced leptin levels. Furthermore, PTG overexpression reversed the glucose intolerance and hyperinsulinemia caused by the HFD and protected against HFD-induced hepatic steatosis. Of note, when fed an HFD, PTG(OE) mice did not show the decrease in hepatic ATP content observed in control animals and had lower expression of neuropeptide Y and higher expression of proopiomelanocortin in the hypothalamus. Additionally, after an overnight fast, PTG(OE) animals presented high liver glycogen content, lower liver triacylglycerol content, and lower serum concentrations of fatty acids and β-hydroxybutyrate than control mice, regardless of whether they were fed an HFD or a standard diet. In conclusion, liver glycogen accumulation caused a reduced food intake, protected against the deleterious effects of an HFD, and diminished the metabolic impact of fasting. Therefore, we propose that hepatic glycogen content be considered a potential target for the pharmacological manipulation of diabetes and obesity.
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Affiliation(s)
- Iliana López-Soldado
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain CIBERDEM, Madrid, Spain
| | - Delia Zafra
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain CIBERDEM, Madrid, Spain
| | - Jordi Duran
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain CIBERDEM, Madrid, Spain
| | - Anna Adrover
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | - Joaquim Calbó
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain CIBERDEM, Madrid, Spain
| | - Joan J Guinovart
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain CIBERDEM, Madrid, Spain Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
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Salm MPA, Horswell SD, Hutchison CE, Speedy HE, Yang X, Liang L, Schadt EE, Cookson WO, Wierzbicki AS, Naoumova RP, Shoulders CC. The origin, global distribution, and functional impact of the human 8p23 inversion polymorphism. Genome Res 2012; 22:1144-53. [PMID: 22399572 PMCID: PMC3371712 DOI: 10.1101/gr.126037.111] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Genomic inversions are an increasingly recognized source of genetic variation. However, a lack of reliable high-throughput genotyping assays for these structures has precluded a full understanding of an inversion's phylogenetic, phenotypic, and population genetic properties. We characterize these properties for one of the largest polymorphic inversions in man (the ∼4.5-Mb 8p23.1 inversion), a structure that encompasses numerous signals of natural selection and disease association. We developed and validated a flexible bioinformatics tool that utilizes SNP data to enable accurate, high-throughput genotyping of the 8p23.1 inversion. This tool was applied retrospectively to diverse genome-wide data sets, revealing significant population stratification that largely follows a clinal “serial founder effect” distribution model. Phylogenetic analyses establish the inversion's ancestral origin within the Homo lineage, indicating that 8p23.1 inversion has occurred independently in the Pan lineage. The human inversion breakpoint was localized to an inverted pair of human endogenous retrovirus elements within the large, flanking low-copy repeats; experimental validation of this breakpoint confirmed these elements as the likely intermediary substrates that sponsored inversion formation. In five data sets, mRNA levels of disease-associated genes were robustly associated with inversion genotype. Moreover, a haplotype associated with systemic lupus erythematosus was restricted to the derived inversion state. We conclude that the 8p23.1 inversion is an evolutionarily dynamic structure that can now be accommodated into the understanding of human genetic and phenotypic diversity.
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Affiliation(s)
- Maximilian P A Salm
- Centre for Endocrinology, Barts & the London School of Medicine & Dentistry, Queen Mary University of London, London, United Kingdom.
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Ros S, García-Rocha M, Calbó J, Guinovart JJ. Restoration of hepatic glycogen deposition reduces hyperglycaemia, hyperphagia and gluconeogenic enzymes in a streptozotocin-induced model of diabetes in rats. Diabetologia 2011; 54:2639-48. [PMID: 21811873 DOI: 10.1007/s00125-011-2238-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 06/10/2011] [Indexed: 01/28/2023]
Abstract
AIMS/HYPOTHESIS Glycogen deposition is impaired in diabetes, thus contributing to the development of hyperglycaemia. Several glucose-lowering strategies have attempted to increase liver glycogen deposition by modulating targets, which eventually trigger the activation of liver glycogen synthase (LGS). However, these targets also alter several other biological processes, and therefore their therapeutic use may be limited. Here we tested the approach of directly activating LGS and evaluated the potential of this strategy as a possible treatment for diabetes. METHODS In this study, we examined the efficacy of directly overproducing a constitutively active form of LGS in the liver to ameliorate streptozotocin-induced diabetes in rats. RESULTS Activated mutant LGS overproduction in the liver of streptozotocin-induced diabetic rats normalised liver glycogen content, despite low levels of glucokinase and circulating insulin. Moreover, this overproduction led to a decrease in food intake and in the production of the main gluconeogenic enzymes, glucose-6-phosphatase, fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase. The resulting combined effect was a reduction in hyperglycaemia. CONCLUSIONS/INTERPRETATION The restoration of liver glycogen ameliorated diabetes and therefore is considered a potential strategy for the treatment of this disease.
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Affiliation(s)
- S Ros
- Institute for Research in Biomedicine (IRB Barcelona), Baldiri Reixac 10, 08028 Barcelona, Spain
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8
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Ros S, Zafra D, Valles-Ortega J, García-Rocha M, Forrow S, Domínguez J, Calbó J, Guinovart JJ. Hepatic overexpression of a constitutively active form of liver glycogen synthase improves glucose homeostasis. J Biol Chem 2010; 285:37170-7. [PMID: 20841354 DOI: 10.1074/jbc.m110.157396] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we tested the efficacy of increasing liver glycogen synthase to improve blood glucose homeostasis. The overexpression of wild-type liver glycogen synthase in rats had no effect on blood glucose homeostasis in either the fed or the fasted state. In contrast, the expression of a constitutively active mutant form of the enzyme caused a significant lowering of blood glucose in the former but not the latter state. Moreover, it markedly enhanced the clearance of blood glucose when fasted rats were challenged with a glucose load. Hepatic glycogen stores in rats overexpressing the activated mutant form of liver glycogen synthase were enhanced in the fed state and in response to an oral glucose load but showed a net decline during fasting. In order to test whether these effects were maintained during long term activation of liver glycogen synthase, we generated liver-specific transgenic mice expressing the constitutively active LGS form. These mice also showed an enhanced capacity to store glycogen in the fed state and an improved glucose tolerance when challenged with a glucose load. Thus, we conclude that the activation of liver glycogen synthase improves glucose tolerance in the fed state without compromising glycogenolysis in the postabsorptive state. On the basis of these findings, we propose that the activation of liver glycogen synthase may provide a potential strategy for improvement of glucose tolerance in the postprandial state.
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Affiliation(s)
- Susana Ros
- Department of Biochemistry and Molecular Biology, Institute for Research in Biomedicine, University of Barcelona, Baldiri Reixac 10, E-08028 Barcelona, Spain
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Pautsch A, Stadler N, Wissdorf O, Langkopf E, Moreth W, Streicher R. Molecular recognition of the protein phosphatase 1 glycogen targeting subunit by glycogen phosphorylase. J Biol Chem 2008; 283:8913-8. [PMID: 18198182 DOI: 10.1074/jbc.m706612200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Disrupting the interaction between glycogen phosphorylase and the glycogen targeting subunit (G(L)) of protein phosphatase 1 is emerging as a novel target for the treatment of type 2 diabetes. To elucidate the molecular basis of binding, we have determined the crystal structure of liver phosphorylase bound to a G(L)-derived peptide. The structure reveals the C terminus of G(L) binding in a hydrophobically collapsed conformation to the allosteric regulator-binding site at the phosphorylase dimer interface. G(L) mimics interactions that are otherwise employed by the activator AMP. Functional studies show that G(L) binds tighter than AMP and confirm that the C-terminal Tyr-Tyr motif is the major determinant for G(L) binding potency. Our study validates the G(L)-phosphorylase interface as a novel target for small molecule interaction.
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Affiliation(s)
- Alexander Pautsch
- Department of Lead Discovery, Boehringer Ingelheim GmbH & Co. KG, Birkendorferstrasse 65, Biberach, Germany.
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10
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Kadotani A, Fujimura M, Nakamura T, Ohyama S, Harada N, Maruki H, Tamai Y, Kanatani A, Eiki JI, Nagata Y. Metabolic impact of overexpression of liver glycogen synthase with serine-to-alanine substitutions in rat primary hepatocytes. Arch Biochem Biophys 2007; 466:283-9. [PMID: 17880910 DOI: 10.1016/j.abb.2007.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 07/28/2007] [Accepted: 08/01/2007] [Indexed: 11/24/2022]
Abstract
To investigate the effect of elevation of liver glycogen synthase (GYS2) activity on glucose and glycogen metabolism, we performed adenoviral overexpression of the mutant GYS2 with six serine-to-alanine substitutions in rat primary hepatocytes. Cell-free assays demonstrated that the serine-to-alanine substitutions caused constitutive activity and electrophoretic mobility shift. In rat primary hepatocytes, overexpression of the mutant GYS2 significantly reduced glucose production by 40% and dramatically induced glycogen synthesis via the indirect pathway rather than the direct pathway. Thus, we conclude that elevation of glycogen synthase activity has an inhibitory effect on glucose production in hepatocytes by shunting gluconeogenic precursors into glycogen. In addition, although intracellular compartmentation of glucose-6-phosphate (G6P) remains unclear in hepatocytes, our results imply that there are at least two G6P pools via gluconeogenesis and due to glucose phosphorylation, and that G6P via gluconeogenesis is preferentially used for glycogen synthesis in hepatocytes.
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Affiliation(s)
- Akito Kadotani
- Tsukuba Research Institute, Banyu Pharmaceutical Co Ltd, 3 Okubo, Tsukuba, Ibaraki, Japan
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11
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Montori-Grau M, Guitart M, Lerin C, Andreu A, Newgard C, García-Martínez C, Gómez-Foix A. Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle. Biochem J 2007; 405:107-13. [PMID: 17555403 PMCID: PMC1925244 DOI: 10.1042/bj20061572] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Glycogen-targeting PP1 (protein phosphatase 1) subunit G(L) (coded for by the PPP1R3B gene) is expressed in human, but not rodent, skeletal muscle. Its effects on muscle glycogen metabolism are unknown. We show that G(L) mRNA levels in primary cultured human myotubes are similar to those in freshly excised muscle, unlike subunits G(M) (gene PPP1R3A) or PTG (protein targeting to glycogen; gene PPP1R3C), which decrease strikingly. In cultured myotubes, expression of the genes coding for G(L), G(M) and PTG is not regulated by glucose or insulin. Overexpression of G(L) activates myotube GS (glycogen synthase), glycogenesis in glucose-replete and -depleted cells and glycogen accumulation. Compared with overexpressed G(M), G(L) has a more potent activating effect on glycogenesis, while marked enhancement of their combined action is only observed in glucose-replete cells. G(L) does not affect GP (glycogen phosphorylase) activity, while co-overexpression with muscle GP impairs G(L) activation of GS in glucose-replete cells. G(L) enhances long-term glycogenesis additively to glucose depletion and insulin, although G(L) does not change the phosphorylation of GSK3 (GS kinase 3) on Ser9 or its upstream regulator kinase Akt/protein kinase B on Ser473, nor its response to insulin. In conclusion, in cultured human myotubes, the G(L) gene is expressed as in muscle tissue and is unresponsive to glucose or insulin, as are G(M) and PTG genes. G(L) activates GS regardless of glucose, does not regulate GP and stimulates glycogenesis in combination with insulin and glucose depletion.
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Affiliation(s)
- Marta Montori-Grau
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Maria Guitart
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Carles Lerin
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Antonio L. Andreu
- †Centre d’Investigació en Bioquímica i Biologia Molecular (A.L.A.), University Hospital Vall d'Hebron, 08035-Barcelona, Spain
| | - Christopher B. Newgard
- ‡Sarah W. Stedman Nutrition and Metabolism Center and Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27704, U.S.A
| | - Cèlia García-Martínez
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Anna M. Gómez-Foix
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
- To whom correspondence should be addressed (email )
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Kim YB, Peroni OD, Aschenbach WG, Minokoshi Y, Kotani K, Zisman A, Kahn CR, Goodyear LJ, Kahn BB. Muscle-specific deletion of the Glut4 glucose transporter alters multiple regulatory steps in glycogen metabolism. Mol Cell Biol 2005; 25:9713-23. [PMID: 16227617 PMCID: PMC1265843 DOI: 10.1128/mcb.25.21.9713-9723.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mice with muscle-specific knockout of the Glut4 glucose transporter (muscle-G4KO) are insulin resistant and mildly diabetic. Here we show that despite markedly reduced glucose transport in muscle, muscle glycogen content in the fasted state is increased. We sought to determine the mechanism(s). Basal glycogen synthase activity is increased by 34% and glycogen phosphorylase activity is decreased by 17% (P < 0.05) in muscle of muscle-G4KO mice. Contraction-induced glycogen breakdown is normal. The increased glycogen synthase activity occurs in spite of decreased signaling through the insulin receptor substrate 1 (IRS-1)-phosphoinositide (PI) 3-kinase-Akt pathway and increased glycogen synthase kinase 3beta (GSK3beta) activity in the basal state. Hexokinase II is increased, leading to an approximately twofold increase in glucose-6-phosphate levels. In addition, the levels of two scaffolding proteins that are glycogen-targeting subunits of protein phosphatase 1 (PP1), the muscle-specific regulatory subunit (RGL) and the protein targeting to glycogen (PTG), are strikingly increased by 3.2- to 4.2-fold in muscle of muscle-G4KO mice compared to wild-type mice. The catalytic activity of PP1, which dephosphorylates and activates glycogen synthase, is also increased. This dominates over the GSK3 effects, since glycogen synthase phosphorylation on the GSK3-regulated site is decreased. Thus, the markedly reduced glucose transport in muscle results in increased glycogen synthase activity due to increased hexokinase II, glucose-6-phosphate, and RGL and PTG levels and enhanced PP1 activity. This, combined with decreased glycogen phosphorylase activity, results in increased glycogen content in muscle in the fasted state when glucose transport is reduced.
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Affiliation(s)
- Young-Bum Kim
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, 99 Brookline Avenue, Boston, MA 02215, USA
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Ceulemans H, Bollen M. Functional diversity of protein phosphatase-1, a cellular economizer and reset button. Physiol Rev 2004; 84:1-39. [PMID: 14715909 DOI: 10.1152/physrev.00013.2003] [Citation(s) in RCA: 490] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The protein serine/threonine phosphatase protein phosphatase-1 (PP1) is a ubiquitous eukaryotic enzyme that regulates a variety of cellular processes through the dephosphorylation of dozens of substrates. This multifunctionality of PP1 relies on its association with a host of function-specific targetting and substrate-specifying proteins. In this review we discuss how PP1 affects the biochemistry and physiology of eukaryotic cells. The picture of PP1 that emerges from this analysis is that of a "green" enzyme that promotes the rational use of energy, the recycling of protein factors, and a reversal of the cell to a basal and/or energy-conserving state. Thus PP1 promotes a shift to the more energy-efficient fuels when nutrients are abundant and stimulates the storage of energy in the form of glycogen. PP1 also enables the relaxation of actomyosin fibers, the return to basal patterns of protein synthesis, and the recycling of transcription and splicing factors. In addition, PP1 plays a key role in the recovery from stress but promotes apoptosis when cells are damaged beyond repair. Furthermore, PP1 downregulates ion pumps and transporters in various tissues and ion channels that are involved in the excitation of neurons. Finally, PP1 promotes the exit from mitosis and maintains cells in the G1 or G2 phases of the cell cycle.
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Affiliation(s)
- Hugo Ceulemans
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, Leuven, Belgium
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Greenberg CC, Meredith KN, Yan L, Brady MJ. Protein targeting to glycogen overexpression results in the specific enhancement of glycogen storage in 3T3-L1 adipocytes. J Biol Chem 2003; 278:30835-42. [PMID: 12805359 DOI: 10.1074/jbc.m303846200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase-1 (PP1) plays an important role in the regulation of glycogen synthesis by insulin. Protein targeting to glycogen (PTG) enhances glycogen accumulation by increasing PP1 activity against glycogen-metabolizing enzymes. However, the specificity of PTG's effects on cellular dephosphorylation and glucose metabolism is unclear. Overexpression of PTG in 3T3-L1 adipocytes using a doxycycline-controllable adenoviral construct resulted in a 10-20-fold increase in PTG levels and an 8-fold increase in glycogen levels. Inclusion of 1 microg/ml doxycycline in the media suppressed PTG expression, and fully reversed all PTG-dependent effects. Infection of 3T3-L1 adipocytes with the PTG adenovirus caused a marked dephosphorylation and activation of glycogen synthase. The effects of PTG seemed specific, because basal and insulin-stimulated phosphorylation of a variety of signaling proteins was unaffected. Indeed, glycogen synthase was the predominant protein whose phosphorylation state was decreased in 32P-labeled cells. PTG overexpression did not alter PP1 protein levels but increased PP1 activity 6-fold against phosphorylase in vitro. In contrast, there was no change in PP1 activity measured using myelin basic protein, suggesting that PTG overexpression specifically directed PP1 activity against glycogen-metabolizing enzymes. To investigate the metabolic consequences of altering PTG levels, glucose uptake and storage in 3T3-L1 adipocytes was measured. PTG overexpression did not affect 2-deoxy-glucose transport rates in basal and insulin-stimulated cells but dramatically enhanced glycogen synthesis rates under both conditions. Despite the large increases in cellular glucose flux upon PTG overexpression, basal and insulin-stimulated glucose incorporation into lipid were unchanged. Cumulatively, these data indicate that PTG overexpression in 3T3-L1 adipocytes discretely stimulates PP1 activity against glycogen synthase and phosphorylase, resulting in a marked and specific increase in glucose uptake and storage as glycogen.
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Affiliation(s)
- Cynthia C Greenberg
- Department of Medicine, The University of Chicago, Chicago, Illinois 60637, USA
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Abstract
PURPOSE OF REVIEW This review depicts recent developments concerning the role of the liver in control of carbohydrate and lipid utilization from ingestion to storage; it covers the liver's influence on food intake, post-absorptive nutrient metabolism and body weight. The mechanisms involved have implications for the pathogenesis of obesity and type II diabetes. RECENT FINDINGS Recent studies have identified some of the molecular and biochemical mechanisms which control whole body and hepatic carbohydrate and lipid metabolism, thus providing the basis of the liver's role in the control of food intake, metabolism, and body weight. Fatty acids are known to effect gene transcription in various ways. Advances in our understanding of the control of glucose and lipid utilization by the liver include (1). a better functional characterization of some newly discovered transcription factors, (2). new discoveries concerning the physiological and pathophysiological role of hepatic glucokinase and of the glycogen-targeting subunits of protein phosphatase-1, and (3). the demonstration of substantial overlap in the molecular control mechanisms of glucose-lipid utilization. Also, impaired insulin signaling due to a certain gene (Foxo1) has emerged as a possible unifying mechanism for various common metabolic abnormalities of type II diabetes. Finally, recent findings confirm and extend previous knowledge about the important role of hepatic nerves in the control of liver and whole body glucose-lipid utilization. SUMMARY The identification of new molecular and neural mechanisms of the hepatic control of glucose-lipid utilization and body weight provides a focus for future studies and may eventually help to develop new treatments for obesity and type II diabetes.
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Affiliation(s)
- Wolfgang Langhans
- Physiology and Animal Husbandry, Institute of Animal Sciences, Schwerzenbach, Switzerland.
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Yang R, Newgard CB. Hepatic expression of a targeting subunit of protein phosphatase-1 in streptozotocin-diabetic rats reverses hyperglycemia and hyperphagia despite depressed glucokinase expression. J Biol Chem 2003; 278:23418-25. [PMID: 12697773 DOI: 10.1074/jbc.m213112200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogen-targeting subunits of protein phosphatase-1 (PP-1) are scaffolding proteins that facilitate the regulation of key enzymes of glycogen metabolism by PP-1. In the current study, we have tested the effects of hepatic expression of GMDeltaC, a truncated version of the muscle-targeting subunit isoform, in rats rendered insulin-deficient via injection of a single moderate dose of streptozotocin (STZ). Three key findings emerged. First, GMDeltaC expression in liver was sufficient to fully normalize blood glucose levels (from 335 +/- 31 mg/dl prior to viral injection to 109 +/- 28 mg/dl 6 days after injection) and liver glycogen content in STZ-injected rats. Second, this normalization occurred despite very low levels of liver glucokinase expression in the insulin-deficient STZ-injected rats. Finally, the hyperphagia induced by STZ injection was completely reversed by GMDeltaC expression in liver. In contrast to these findings with GMDeltaC, overexpression of another targeting subunit, GL, in STZ-injected rats caused a large increase in liver glycogen stores but only a transient decrease in food intake and blood glucose levels. The surprising demonstration of a glucose-lowering effect of GMDeltaC in the background of depressed hepatic glucokinase expression suggests that controlled stimulation of liver glycogen storage may be an effective mechanism for improving glucose homeostasis, even when normal pathways of glucose disposal are impaired.
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Affiliation(s)
- Ruojing Yang
- Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA
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