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MacDonald T, Ryback B, da Silva Pereira JA, Wei S, Mendez B, Cai E, Ishikawa Y, Weir G, Bonner-Weir S, Kissler S, Yi P. Renalase inhibition regulates β cell metabolism to defend against acute and chronic stress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598322. [PMID: 38915698 PMCID: PMC11195134 DOI: 10.1101/2024.06.11.598322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Renalase (Rnls), annotated as an oxidase enzyme, is a GWAS gene associated with Type 1 Diabetes (T1D) risk. We previously discovered that Rnls inhibition delays diabetes onset in mouse models of T1D in vivo , and protects pancreatic β cells against autoimmune killing, ER and oxidative stress in vitro . The molecular biochemistry and functions of Rnls are entirely uncharted. Here we find that Rnls inhibition defends against loss of β cell mass and islet dysfunction in chronically stressed Akita mice in vivo . We used RNA sequencing, untargeted and targeted metabolomics and metabolic function experiments in mouse and human β cells and discovered a robust and conserved metabolic shift towards glycolysis, amino acid abundance and GSH synthesis to counter protein misfolding stress, in vitro . Our work illustrates a function for Rnls in mammalian cells, and suggests an axis by which manipulating intrinsic properties of β cells can rewire metabolism to protect against diabetogenic stress.
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Muñoz F, Fex M, Moritz T, Mulder H, Cataldo LR. Unique features of β-cell metabolism are lost in type 2 diabetes. Acta Physiol (Oxf) 2024; 240:e14148. [PMID: 38656044 DOI: 10.1111/apha.14148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/28/2024] [Accepted: 04/05/2024] [Indexed: 04/26/2024]
Abstract
Pancreatic β cells play an essential role in the control of systemic glucose homeostasis as they sense blood glucose levels and respond by secreting insulin. Upon stimulating glucose uptake in insulin-sensitive tissues post-prandially, this anabolic hormone restores blood glucose levels to pre-prandial levels. Maintaining physiological glucose levels thus relies on proper β-cell function. To fulfill this highly specialized nutrient sensor role, β cells have evolved a unique genetic program that shapes its distinct cellular metabolism. In this review, the unique genetic and metabolic features of β cells will be outlined, including their alterations in type 2 diabetes (T2D). β cells selectively express a set of genes in a cell type-specific manner; for instance, the glucose activating hexokinase IV enzyme or Glucokinase (GCK), whereas other genes are selectively "disallowed", including lactate dehydrogenase A (LDHA) and monocarboxylate transporter 1 (MCT1). This selective gene program equips β cells with a unique metabolic apparatus to ensure that nutrient metabolism is coupled to appropriate insulin secretion, thereby avoiding hyperglycemia, as well as life-threatening hypoglycemia. Unlike most cell types, β cells exhibit specialized bioenergetic features, including supply-driven rather than demand-driven metabolism and a high basal mitochondrial proton leak respiration. The understanding of these unique genetically programmed metabolic features and their alterations that lead to β-cell dysfunction is crucial for a comprehensive understanding of T2D pathophysiology and the development of innovative therapeutic approaches for T2D patients.
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Affiliation(s)
- Felipe Muñoz
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
| | - Malin Fex
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
| | - Thomas Moritz
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hindrik Mulder
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
| | - Luis Rodrigo Cataldo
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Chong ACN, Vandana JJ, Jeng G, Li G, Meng Z, Duan X, Zhang T, Qiu Y, Duran-Struuck R, Coker K, Wang W, Li Y, Min Z, Zuo X, de Silva N, Chen Z, Naji A, Hao M, Liu C, Chen S. Checkpoint kinase 2 controls insulin secretion and glucose homeostasis. Nat Chem Biol 2024; 20:566-576. [PMID: 37945898 PMCID: PMC11062908 DOI: 10.1038/s41589-023-01466-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 10/03/2023] [Indexed: 11/12/2023]
Abstract
After the discovery of insulin, a century ago, extensive work has been done to unravel the molecular network regulating insulin secretion. Here we performed a chemical screen and identified AZD7762, a compound that potentiates glucose-stimulated insulin secretion (GSIS) of a human β cell line, healthy and type 2 diabetic (T2D) human islets and primary cynomolgus macaque islets. In vivo studies in diabetic mouse models and cynomolgus macaques demonstrated that AZD7762 enhances GSIS and improves glucose tolerance. Furthermore, genetic manipulation confirmed that ablation of CHEK2 in human β cells results in increased insulin secretion. Consistently, high-fat-diet-fed Chk2-/- mice show elevated insulin secretion and improved glucose clearance. Finally, untargeted metabolic profiling demonstrated the key role of the CHEK2-PP2A-PLK1-G6PD-PPP pathway in insulin secretion. This study successfully identifies a previously unknown insulin secretion regulating pathway that is conserved across rodents, cynomolgus macaques and human β cells in both healthy and T2D conditions.
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Affiliation(s)
- Angie Chi Nok Chong
- Department of Surgery, Weill Cornell Medicine, New York City, NY, USA
- Center for Genomic Health, Weill Cornell Medicine, New York City, NY, USA
| | - J Jeya Vandana
- Department of Surgery, Weill Cornell Medicine, New York City, NY, USA
- Center for Genomic Health, Weill Cornell Medicine, New York City, NY, USA
- Tri-Institutional PhD Program in Chemical Biology, New York City, NY, USA
| | - Ginnie Jeng
- Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ge Li
- Department of Medicine, Weill Cornell Medicine, New York City, NY, USA
- Department of Biological Sciences, Bronx Community College, City University of New York, Bronx, NY, USA
| | - Zihe Meng
- Department of Surgery, Weill Cornell Medicine, New York City, NY, USA
- Center for Genomic Health, Weill Cornell Medicine, New York City, NY, USA
| | - Xiaohua Duan
- Department of Surgery, Weill Cornell Medicine, New York City, NY, USA
- Center for Genomic Health, Weill Cornell Medicine, New York City, NY, USA
| | - Tuo Zhang
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York City, NY, USA
| | - Yunping Qiu
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Raimon Duran-Struuck
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA
| | - Kimberly Coker
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA
| | - Wei Wang
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Yanjing Li
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Zaw Min
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Xi Zuo
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Neranjan de Silva
- Department of Surgery, Weill Cornell Medicine, New York City, NY, USA
| | - Zhengming Chen
- Department of Population Health Sciences, Weill Cornell Medicine, New York City, NY, USA
| | - Ali Naji
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA
| | - Mingming Hao
- Department of Biochemistry, Weill Cornell Medicine, New York City, NY, USA
| | - Chengyang Liu
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
| | - Shuibing Chen
- Department of Surgery, Weill Cornell Medicine, New York City, NY, USA.
- Center for Genomic Health, Weill Cornell Medicine, New York City, NY, USA.
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Varney MJ, Benovic JL. The Role of G Protein-Coupled Receptors and Receptor Kinases in Pancreatic β-Cell Function and Diabetes. Pharmacol Rev 2024; 76:267-299. [PMID: 38351071 PMCID: PMC10877731 DOI: 10.1124/pharmrev.123.001015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/01/2023] [Accepted: 12/07/2023] [Indexed: 02/16/2024] Open
Abstract
Type 2 diabetes (T2D) mellitus has emerged as a major global health concern that has accelerated in recent years due to poor diet and lifestyle. Afflicted individuals have high blood glucose levels that stem from the inability of the pancreas to make enough insulin to meet demand. Although medication can help to maintain normal blood glucose levels in individuals with chronic disease, many of these medicines are outdated, have severe side effects, and often become less efficacious over time, necessitating the need for insulin therapy. G protein-coupled receptors (GPCRs) regulate many physiologic processes, including blood glucose levels. In pancreatic β cells, GPCRs regulate β-cell growth, apoptosis, and insulin secretion, which are all critical in maintaining sufficient β-cell mass and insulin output to ensure euglycemia. In recent years, new insights into the signaling of incretin receptors and other GPCRs have underscored the potential of these receptors as desirable targets in the treatment of diabetes. The signaling of these receptors is modulated by GPCR kinases (GRKs) that phosphorylate agonist-activated GPCRs, marking the receptor for arrestin binding and internalization. Interestingly, genome-wide association studies using diabetic patient cohorts link the GRKs and arrestins with T2D. Moreover, recent reports show that GRKs and arrestins expressed in the β cell serve a critical role in the regulation of β-cell function, including β-cell growth and insulin secretion in both GPCR-dependent and -independent pathways. In this review, we describe recent insights into GPCR signaling and the importance of GRK function in modulating β-cell physiology. SIGNIFICANCE STATEMENT: Pancreatic β cells contain a diverse array of G protein-coupled receptors (GPCRs) that have been shown to improve β-cell function and survival, yet only a handful have been successfully targeted in the treatment of diabetes. This review discusses recent advances in our understanding of β-cell GPCR pharmacology and regulation by GPCR kinases while also highlighting the necessity of investigating islet-enriched GPCRs that have largely been unexplored to unveil novel treatment strategies.
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Affiliation(s)
- Matthew J Varney
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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Pan Y, Li Y, Chhetri JK, Liu P, Li B, Liu Z, Shui G, Ma L. Dysregulation of acyl carnitines, pentose phosphate pathway and arginine and ornithine metabolism are associated with decline in intrinsic capacity in Chinese older adults. Aging Clin Exp Res 2024; 36:36. [PMID: 38345670 PMCID: PMC10861606 DOI: 10.1007/s40520-023-02654-x] [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: 07/06/2023] [Accepted: 11/03/2023] [Indexed: 02/15/2024]
Abstract
BACKGROUND Intrinsic capacity is the combination of individual physical and mental abilities, reflecting the aging degree of the older adults. However, the mechanisms and metabolic characteristics of the decline in intrinsic capacity are still unclear. AIMS To identify metabolic signatures and associated pathways of decline in intrinsic capacity based on the metabolite features. METHODS We recruited 70 participants aged 77.19 ± 8.31 years. The five domains of intrinsic capacity were assessed by Short Physical Performance Battery (for mobility), Montreal cognition assessment (for cognition), 30-Item Geriatric Depression Scale (for psychology), self-reported hearing/visual impairment (for sensory) and Nutritional risk screening (for vitality), respectively. The serum samples of participants were analyzed by liquid chromatography-mass spectrometry-based metabolomics, followed by metabolite set enrichment analysis and metabolic pathway analysis. RESULTS There were 50 participants with a decline in intrinsic capacity in at least one of the domains. A total of 349 metabolites were identified from their serum samples. Overall, 24 differential metabolites, 5 metabolite sets and 13 pathways were associated with the decline in intrinsic capacity. DISCUSSION Our results indicated that decline in intrinsic capacity had unique metabolomic profiles. CONCLUSION The specific change of acyl carnitines was observed to be a feature of decline in intrinsic capacity. Dysregulation of the pentose phosphate pathway and of arginine and ornithine metabolism was strongly associated with the decline in intrinsic capacity.
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Affiliation(s)
- Yiming Pan
- Department of Geriatrics, Xuanwu Hospital, Capital Medical University, National Research Center for Geriatric Medicine, 45 Changchun Street, Beijing, 100053, China
- National Clinical Research Center for Geriatric Diseases, Xuanwu Hospital of Capital Medical University, Beijing, 100053, China
| | - Yun Li
- Department of Geriatrics, Xuanwu Hospital, Capital Medical University, National Research Center for Geriatric Medicine, 45 Changchun Street, Beijing, 100053, China.
- National Clinical Research Center for Geriatric Diseases, Xuanwu Hospital of Capital Medical University, Beijing, 100053, China.
| | - Jagadish K Chhetri
- Department of Geriatrics, Xuanwu Hospital, Capital Medical University, National Research Center for Geriatric Medicine, 45 Changchun Street, Beijing, 100053, China
- Department of Neurology and Neurobiology, Xuanwu Hospital of Capital Medical University, Beijing, 100053, China
- National Clinical Research Center for Geriatric Diseases, Xuanwu Hospital of Capital Medical University, Beijing, 100053, China
| | - Pan Liu
- Department of Geriatrics, Xuanwu Hospital, Capital Medical University, National Research Center for Geriatric Medicine, 45 Changchun Street, Beijing, 100053, China
- National Clinical Research Center for Geriatric Diseases, Xuanwu Hospital of Capital Medical University, Beijing, 100053, China
| | - Bowen Li
- LipidALL Technologies Company Limited, Changzhou, 213022, Jiangsu, China
| | - Zuyun Liu
- Center for Clinical Big Data and Analytics, Second Affiliated Hospital and Department of Big Data in Health Science, School of Public Health, The Key Laboratory of Intelligent Preventive Medicine of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058, Zhejiang, China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Lina Ma
- Department of Geriatrics, Xuanwu Hospital, Capital Medical University, National Research Center for Geriatric Medicine, 45 Changchun Street, Beijing, 100053, China.
- National Clinical Research Center for Geriatric Diseases, Xuanwu Hospital of Capital Medical University, Beijing, 100053, China.
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Moon DO. NADPH Dynamics: Linking Insulin Resistance and β-Cells Ferroptosis in Diabetes Mellitus. Int J Mol Sci 2023; 25:342. [PMID: 38203517 PMCID: PMC10779351 DOI: 10.3390/ijms25010342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/20/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
This review offers an in-depth exploration of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) in metabolic health. It delves into how NADPH affects insulin secretion, influences insulin resistance, and plays a role in ferroptosis. NADPH, a critical cofactor in cellular antioxidant systems and lipid synthesis, plays a central role in maintaining metabolic homeostasis. In adipocytes and skeletal muscle, NADPH influences the pathophysiology of insulin resistance, a hallmark of metabolic disorders such as type 2 diabetes and obesity. The review explores the mechanisms by which NADPH contributes to or mitigates insulin resistance, including its role in lipid and reactive oxygen species (ROS) metabolism. Parallelly, the paper investigates the dual nature of NADPH in the context of pancreatic β-cell health, particularly in its relation to ferroptosis, an iron-dependent form of programmed cell death. While NADPH's antioxidative properties are crucial for preventing oxidative damage in β-cells, its involvement in lipid metabolism can potentiate ferroptotic pathways under certain pathological conditions. This complex relationship underscores the delicate balance of NADPH homeostasis in pancreatic health and diabetes pathogenesis. By integrating findings from recent studies, this review aims to illuminate the nuanced roles of NADPH in different tissues and its potential as a therapeutic target. Understanding these dynamics offers vital insights into the development of more effective strategies for managing insulin resistance and preserving pancreatic β-cell function, thereby advancing the treatment of metabolic diseases.
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Affiliation(s)
- Dong-Oh Moon
- Department of Biology Education, Daegu University, 201 Daegudae-ro, Gyeongsan-si 38453, Gyeongsangbuk-do, Republic of Korea
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7
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Ježek P. Pitfalls of Mitochondrial Redox Signaling Research. Antioxidants (Basel) 2023; 12:1696. [PMID: 37759999 PMCID: PMC10525995 DOI: 10.3390/antiox12091696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/27/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
Redox signaling from mitochondria (mt) to the cytosol and plasma membrane (PM) has been scarcely reported, such as in the case of hypoxic cell adaptation or (2-oxo-) 2-keto-isocaproate (KIC) β-like-oxidation stimulating insulin secretion in pancreatic β-cells. Mutual redox state influence between mitochondrial major compartments, the matrix and the intracristal space, and the cytosol is therefore derived theoretically in this article to predict possible conditions, when mt-to-cytosol and mt-to-PM signals may occur, as well as conditions in which the cytosolic redox signaling is not overwhelmed by the mitochondrial antioxidant capacity. Possible peroxiredoxin 3 participation in mt-to-cytosol redox signaling is discussed, as well as another specific case, whereby mitochondrial superoxide release is diminished, whereas the matrix MnSOD is activated. As a result, the enhanced conversion to H2O2 allows H2O2 diffusion into the cytosol, where it could be a predominant component of the H2O2 release. In both of these ways, mt-to-cytosol and mt-to-PM signals may be realized. Finally, the use of redox-sensitive probes is discussed, which disturb redox equilibria, and hence add a surplus redox-buffering to the compartment, where they are localized. Specifically, when attempts to quantify net H2O2 fluxes are to be made, this should be taken into account.
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Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, 14220 Prague, Czech Republic
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Barsby T, Vähäkangas E, Ustinov J, Montaser H, Ibrahim H, Lithovius V, Kuuluvainen E, Chandra V, Saarimäki-Vire J, Katajisto P, Hietakangas V, Otonkoski T. Aberrant metabolite trafficking and fuel sensitivity in human pluripotent stem cell-derived islets. Cell Rep 2023; 42:112970. [PMID: 37556323 DOI: 10.1016/j.celrep.2023.112970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 06/09/2023] [Accepted: 07/26/2023] [Indexed: 08/11/2023] Open
Abstract
Pancreatic islets regulate blood glucose homeostasis through the controlled release of insulin; however, current metabolic models of glucose-sensitive insulin secretion are incomplete. A comprehensive understanding of islet metabolism is integral to studies of endocrine cell development as well as diabetic islet dysfunction. Human pluripotent stem cell-derived islets (SC-islets) are a developmentally relevant model of human islet function that have great potential in providing a cure for type 1 diabetes. Using multiple 13C-labeled metabolic fuels, we demonstrate that SC-islets show numerous divergent patterns of metabolite trafficking in proposed insulin release pathways compared with primary human islets but are still reliant on mitochondrial aerobic metabolism to derive function. Furthermore, reductive tricarboxylic acid cycle activity and glycolytic metabolite cycling occur in SC-islets, suggesting that non-canonical coupling factors are also present. In aggregate, we show that many facets of SC-islet metabolism overlap with those of primary islets, albeit with a retained immature signature.
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Affiliation(s)
- Tom Barsby
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
| | - Eliisa Vähäkangas
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jarkko Ustinov
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Hossam Montaser
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Hazem Ibrahim
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Väinö Lithovius
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Emilia Kuuluvainen
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Vikash Chandra
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jonna Saarimäki-Vire
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Pekka Katajisto
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Ville Hietakangas
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Timo Otonkoski
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
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9
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Deepa Maheshvare M, Raha S, König M, Pal D. A pathway model of glucose-stimulated insulin secretion in the pancreatic β-cell. Front Endocrinol (Lausanne) 2023; 14:1185656. [PMID: 37600713 PMCID: PMC10433753 DOI: 10.3389/fendo.2023.1185656] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 06/08/2023] [Indexed: 08/22/2023] Open
Abstract
The pancreas plays a critical role in maintaining glucose homeostasis through the secretion of hormones from the islets of Langerhans. Glucose-stimulated insulin secretion (GSIS) by the pancreatic β-cell is the main mechanism for reducing elevated plasma glucose. Here we present a systematic modeling workflow for the development of kinetic pathway models using the Systems Biology Markup Language (SBML). Steps include retrieval of information from databases, curation of experimental and clinical data for model calibration and validation, integration of heterogeneous data including absolute and relative measurements, unit normalization, data normalization, and model annotation. An important factor was the reproducibility and exchangeability of the model, which allowed the use of various existing tools. The workflow was applied to construct a novel data-driven kinetic model of GSIS in the pancreatic β-cell based on experimental and clinical data from 39 studies spanning 50 years of pancreatic, islet, and β-cell research in humans, rats, mice, and cell lines. The model consists of detailed glycolysis and phenomenological equations for insulin secretion coupled to cellular energy state, ATP dynamics and (ATP/ADP ratio). Key findings of our work are that in GSIS there is a glucose-dependent increase in almost all intermediates of glycolysis. This increase in glycolytic metabolites is accompanied by an increase in energy metabolites, especially ATP and NADH. One of the few decreasing metabolites is ADP, which, in combination with the increase in ATP, results in a large increase in ATP/ADP ratios in the β-cell with increasing glucose. Insulin secretion is dependent on ATP/ADP, resulting in glucose-stimulated insulin secretion. The observed glucose-dependent increase in glycolytic intermediates and the resulting change in ATP/ADP ratios and insulin secretion is a robust phenomenon observed across data sets, experimental systems and species. Model predictions of the glucose-dependent response of glycolytic intermediates and biphasic insulin secretion are in good agreement with experimental measurements. Our model predicts that factors affecting ATP consumption, ATP formation, hexokinase, phosphofructokinase, and ATP/ADP-dependent insulin secretion have a major effect on GSIS. In conclusion, we have developed and applied a systematic modeling workflow for pathway models that allowed us to gain insight into key mechanisms in GSIS in the pancreatic β-cell.
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Affiliation(s)
- M. Deepa Maheshvare
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore, India
| | - Soumyendu Raha
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore, India
| | - Matthias König
- Institute for Biology, Institute for Theoretical Biology, Humboldt-University Berlin, Berlin, Germany
| | - Debnath Pal
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore, India
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10
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Zhang S, Zhang Y, Wen Z, Yang Y, Bu T, Bu X, Ni Q. Cognitive dysfunction in diabetes: abnormal glucose metabolic regulation in the brain. Front Endocrinol (Lausanne) 2023; 14:1192602. [PMID: 37396164 PMCID: PMC10312370 DOI: 10.3389/fendo.2023.1192602] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/25/2023] [Indexed: 07/04/2023] Open
Abstract
Cognitive dysfunction is increasingly recognized as a complication and comorbidity of diabetes, supported by evidence of abnormal brain structure and function. Although few mechanistic metabolic studies have shown clear pathophysiological links between diabetes and cognitive dysfunction, there are several plausible ways in which this connection may occur. Since, brain functions require a constant supply of glucose as an energy source, the brain may be more susceptible to abnormalities in glucose metabolism. Glucose metabolic abnormalities under diabetic conditions may play an important role in cognitive dysfunction by affecting glucose transport and reducing glucose metabolism. These changes, along with oxidative stress, inflammation, mitochondrial dysfunction, and other factors, can affect synaptic transmission, neural plasticity, and ultimately lead to impaired neuronal and cognitive function. Insulin signal triggers intracellular signal transduction that regulates glucose transport and metabolism. Insulin resistance, one hallmark of diabetes, has also been linked with impaired cerebral glucose metabolism in the brain. In this review, we conclude that glucose metabolic abnormalities play a critical role in the pathophysiological alterations underlying diabetic cognitive dysfunction (DCD), which is associated with multiple pathogenic factors such as oxidative stress, mitochondrial dysfunction, inflammation, and others. Brain insulin resistance is highly emphasized and characterized as an important pathogenic mechanism in the DCD.
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Affiliation(s)
| | | | | | | | | | | | - Qing Ni
- Department of Endocrinology, Guang’ anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
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11
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Deepa Maheshvare M, Raha S, König M, Pal D. A Consensus Model of Glucose-Stimulated Insulin Secretion in the Pancreatic β -Cell. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.10.532028. [PMID: 36945414 PMCID: PMC10028967 DOI: 10.1101/2023.03.10.532028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
Abstract
The pancreas plays a critical role in maintaining glucose homeostasis through the secretion of hormones from the islets of Langerhans. Glucose-stimulated insulin secretion (GSIS) by the pancreatic β -cell is the main mechanism for reducing elevated plasma glucose. Here we present a systematic modeling workflow for the development of kinetic pathway models using the Systems Biology Markup Language (SBML). Steps include retrieval of information from databases, curation of experimental and clinical data for model calibration and validation, integration of heterogeneous data including absolute and relative measurements, unit normalization, data normalization, and model annotation. An important factor was the reproducibility and exchangeability of the model, which allowed the use of various existing tools. The workflow was applied to construct the first consensus model of GSIS in the pancreatic β -cell based on experimental and clinical data from 39 studies spanning 50 years of pancreatic, islet, and β -cell research in humans, rats, mice, and cell lines. The model consists of detailed glycolysis and equations for insulin secretion coupled to cellular energy state (ATP/ADP ratio). Key findings of our work are that in GSIS there is a glucose-dependent increase in almost all intermediates of glycolysis. This increase in glycolytic metabolites is accompanied by an increase in energy metabolites, especially ATP and NADH. One of the few decreasing metabolites is ADP, which, in combination with the increase in ATP, results in a large increase in ATP/ADP ratios in the β -cell with increasing glucose. Insulin secretion is dependent on ATP/ADP, resulting in glucose-stimulated insulin secretion. The observed glucose-dependent increase in glycolytic intermediates and the resulting change in ATP/ADP ratios and insulin secretion is a robust phenomenon observed across data sets, experimental systems and species. Model predictions of the glucose-dependent response of glycolytic intermediates and insulin secretion are in good agreement with experimental measurements. Our model predicts that factors affecting ATP consumption, ATP formation, hexokinase, phosphofructokinase, and ATP/ADP-dependent insulin secretion have a major effect on GSIS. In conclusion, we have developed and applied a systematic modeling workflow for pathway models that allowed us to gain insight into key mechanisms in GSIS in the pancreatic β -cell.
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12
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Wang X, Sun J, Li J, Cai L, Chen Q, Wang Y, Yang Z, Liu W, Lv H, Wang Z. Bidirectional Mendelian randomization study of insulin-related traits and risk of ovarian cancer. Front Endocrinol (Lausanne) 2023; 14:1131767. [PMID: 36936171 PMCID: PMC10014907 DOI: 10.3389/fendo.2023.1131767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 02/09/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND It is well known that the occurrence and development of ovarian cancer are closely related to the patient's weight and various endocrine factors in the body. AIM Mendelian randomization (MR) was used to analyze the bidirectional relationship between insulin related characteristics and ovarian cancer. METHODS The data on insulin related characteristics are from up to 5567 diabetes free patients from 10 studies, mainly including fasting insulin level, insulin secretion rate, peak insulin response, etc. For ovarian cancer, UK Biobank data just updated in 2021 was selected, of which the relevant gene data was from 199741 Europeans. Mendelian randomization method was selected, with inverse variance weighting (IVW) as the main estimation, while MR Pleiotropy, MR Egger, weighted median and other methods were used to detect the heterogeneity of data and whether there was multi validity affecting conclusions. RESULTS Among all insulin related indicators (fasting insulin level, insulin secretion rate, peak insulin response), the insulin secretion rate was selected to have a causal relationship with the occurrence of ovarian cancer (IVW, P < 0.05), that is, the risk of ovarian cancer increased with the decrease of insulin secretion rate. At the same time, we tested the heterogeneity and polymorphism of this indicator, and the results were non-existent, which ensured the accuracy of the analysis results. Reverse causal analysis showed that there was no causal effect between the two (P>0.05). CONCLUSION The impairment of the insulin secretion rate has a causal effect on the risk of ovarian cancer, which was confirmed by Mendel randomization. This suggests that the human glucose metabolism cycle represented by insulin secretion plays an important role in the pathogenesis of ovarian cancer, which provides a new idea for preventing the release of ovarian cancer.
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Affiliation(s)
- Xinghao Wang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jing Sun
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jia Li
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Linkun Cai
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Qian Chen
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Yiling Wang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Zhenghan Yang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Wenjuan Liu
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Han Lv
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- *Correspondence: Han Lv, ; Zhenchang Wang,
| | - Zhenchang Wang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- *Correspondence: Han Lv, ; Zhenchang Wang,
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13
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Gelbach PE, Zheng D, Fraser SE, White KL, Graham NA, Finley SD. Kinetic and data-driven modeling of pancreatic β-cell central carbon metabolism and insulin secretion. PLoS Comput Biol 2022; 18:e1010555. [PMID: 36251711 PMCID: PMC9612825 DOI: 10.1371/journal.pcbi.1010555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/27/2022] [Accepted: 09/08/2022] [Indexed: 11/06/2022] Open
Abstract
Pancreatic β-cells respond to increased extracellular glucose levels by initiating a metabolic shift. That change in metabolism is part of the process of glucose-stimulated insulin secretion and is of particular interest in the context of diabetes. However, we do not fully understand how the coordinated changes in metabolic pathways and metabolite products influence insulin secretion. In this work, we apply systems biology approaches to develop a detailed kinetic model of the intracellular central carbon metabolic pathways in pancreatic β-cells upon stimulation with high levels of glucose. The model is calibrated to published metabolomics datasets for the INS1 823/13 cell line, accurately capturing the measured metabolite fold-changes. We first employed the calibrated mechanistic model to estimate the stimulated cell's fluxome. We then used the predicted network fluxes in a data-driven approach to build a partial least squares regression model. By developing the combined kinetic and data-driven modeling framework, we gain insights into the link between β-cell metabolism and glucose-stimulated insulin secretion. The combined modeling framework was used to predict the effects of common anti-diabetic pharmacological interventions on metabolite levels, flux through the metabolic network, and insulin secretion. Our simulations reveal targets that can be modulated to enhance insulin secretion. The model is a promising tool to contextualize and extend the usefulness of metabolomics data and to predict dynamics and metabolite levels that are difficult to measure in vitro. In addition, the modeling framework can be applied to identify, explain, and assess novel and clinically-relevant interventions that may be particularly valuable in diabetes treatment.
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Affiliation(s)
- Patrick E. Gelbach
- Department of Biomedical Engineering, USC, Los Angeles, California, United States of America
| | - Dongqing Zheng
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
| | - Scott E. Fraser
- Translational Imaging Center, University of Southern California, Los Angeles, California, United States of America
| | - Kate L. White
- Departments of Biological Sciences and Chemistry, Bridge Institute, USC Michelson Center, USC, Los Angeles, California, United States of America
| | - Nicholas A. Graham
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
| | - Stacey D. Finley
- Department of Biomedical Engineering, USC, Los Angeles, California, United States of America
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
- Department of Quantitative and Computational Biology, USC, Los Angeles, California, United States of America
- * E-mail:
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14
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Marques C, Liu L, Duncan KD, Lanekoff I. A Direct Infusion Probe for Rapid Metabolomics of Low-Volume Samples. Anal Chem 2022; 94:12875-12883. [PMID: 36070505 PMCID: PMC9494293 DOI: 10.1021/acs.analchem.2c02918] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Targeted and nontargeted metabolomics has the potential
to evaluate
and detect global metabolite changes in biological systems. Direct
infusion mass spectrometric analysis enables detection of all ionizable
small molecules, thus simultaneously providing information on both
metabolites and lipids in chemically complex samples. However, to
unravel the heterogeneity of the metabolic status of cells in culture
and tissue a low number of cells per sample should be analyzed with
high sensitivity, which requires low sample volumes. Here, we present
the design and characterization of the direct infusion probe, DIP.
The DIP is simple to build and position directly in front of a mass
spectrometer for rapid metabolomics of chemically complex biological
samples using pneumatically assisted electrospray ionization at 1
μL/min flow rate. The resulting data is acquired in a square
wave profile with minimal carryover between samples that enhances
throughput and enables several minutes of uniform MS signal from 5
μL sample volumes. The DIP was applied to study the intracellular
metabolism of insulin secreting INS-1 cells and the results show that
exposure to 20 mM glucose for 15 min significantly alters the abundance
of several small metabolites, amino acids, and lipids.
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Affiliation(s)
- Cátia Marques
- Department of Chemistry─BMC, Uppsala University, 75123 Uppsala, Sweden
| | - Liangwen Liu
- Department of Medical Cell Biology, Uppsala University, 75123 Uppsala, Sweden
| | - Kyle D Duncan
- Department of Chemistry─BMC, Uppsala University, 75123 Uppsala, Sweden
| | - Ingela Lanekoff
- Department of Chemistry─BMC, Uppsala University, 75123 Uppsala, Sweden
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15
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Metabolic cycles and signals for insulin secretion. Cell Metab 2022; 34:947-968. [PMID: 35728586 PMCID: PMC9262871 DOI: 10.1016/j.cmet.2022.06.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 06/01/2022] [Accepted: 06/04/2022] [Indexed: 02/03/2023]
Abstract
In this review, we focus on recent developments in our understanding of nutrient-induced insulin secretion that challenge a key aspect of the "canonical" model, in which an oxidative phosphorylation-driven rise in ATP production closes KATP channels. We discuss the importance of intrinsic β cell metabolic oscillations; the phasic alignment of relevant metabolic cycles, shuttles, and shunts; and how their temporal and compartmental relationships align with the triggering phase or the secretory phase of pulsatile insulin secretion. Metabolic signaling components are assigned regulatory, effectory, and/or homeostatic roles vis-à-vis their contribution to glucose sensing, signal transmission, and resetting the system. Taken together, these functions provide a framework for understanding how allostery, anaplerosis, and oxidative metabolism are integrated into the oscillatory behavior of the secretory pathway. By incorporating these temporal as well as newly discovered spatial aspects of β cell metabolism, we propose a much-refined MitoCat-MitoOx model of the signaling process for the field to evaluate.
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16
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Ishihara H. Metabolism-secretion coupling in glucose-stimulated insulin secretion. Diabetol Int 2022; 13:463-470. [PMID: 35693987 PMCID: PMC9174369 DOI: 10.1007/s13340-022-00576-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 02/27/2022] [Indexed: 01/09/2023]
Abstract
Pancreatic β-cells in the islets of Langerhans secrete insulin in response to blood glucose levels. Precise control of the amount of insulin secreted is of critical importance for maintaining systemic carbohydrate homeostasis. It is now well established that glucose induced production of ATP from ADP and the KATP channel closure elevate cytosolic Ca2+, triggering insulin exocytosis in β-cells. However, for full activation of insulin secretion by glucose, other mechanisms besides Ca2+ elevation are needed. These mechanisms are the targets of current research and include intracellular metabolic pathways branching from glycolysis. They are metabolic pathways originating from the TCA cycle intermediates, the glycerolipid/free fatty acid cycle and the pentose phosphate pathway. Signaling effects of these pathways including degradation (removal) of protein SUMOylation, modulation of insulin vesicular energetics, and lipid modulation of exocytotic machinery may converge to fulfill insulin secretion, though the precise mechanisms have yet to be elucidated. This mini-review summarize recent advances in research on metabolic coupling mechanisms functioning in insulin secretion.
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Affiliation(s)
- Hisamitsu Ishihara
- Division of Diabetes and Metabolism, Nihon University School of Medicine, 30-1 Oyaguchi-kamicho, Itabashi-ku, Tokyo, 173-8610 Japan
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17
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Rodrigues-dos-Santos K, Roy G, Binns DD, Grzemska MG, Barella LF, Armoo F, McCoy MK, Huynh AV, Yang JZ, Posner BA, Cobb MH, Kalwat MA. Small Molecule-mediated Insulin Hypersecretion Induces Transient ER Stress Response and Loss of Beta Cell Function. Endocrinology 2022; 163:6596276. [PMID: 35641126 PMCID: PMC9225822 DOI: 10.1210/endocr/bqac081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Indexed: 11/19/2022]
Abstract
Pancreatic islet beta cells require a fine-tuned endoplasmic reticulum (ER) stress response for normal function; abnormal ER stress contributes to diabetes pathogenesis. Here, we identified a small molecule, SW016789, with time-dependent effects on beta cell ER stress and function. Acute treatment with SW016789 potentiated nutrient-induced calcium influx and insulin secretion, while chronic exposure to SW016789 transiently induced ER stress and shut down secretory function in a reversible manner. Distinct from the effects of thapsigargin, SW016789 did not affect beta cell viability or apoptosis, potentially due to a rapid induction of adaptive genes, weak signaling through the eIF2α kinase PERK, and lack of oxidative stress gene Txnip induction. We determined that SW016789 acted upstream of voltage-dependent calcium channels (VDCCs) and potentiated nutrient- but not KCl-stimulated calcium influx. Measurements of metabolomics, oxygen consumption rate, and G protein-coupled receptor signaling did not explain the potentiating effects of SW016789. In chemical cotreatment experiments, we discovered synergy between SW016789 and activators of protein kinase C and VDCCs, suggesting involvement of these pathways in the mechanism of action. Finally, chronically elevated calcium influx was required for the inhibitory impact of SW016789, as blockade of VDCCs protected human islets and MIN6 beta cells from hypersecretion-induced dysfunction. We conclude that beta cells undergoing this type of pharmacological hypersecretion have the capacity to suppress their function to mitigate ER stress and avoid apoptosis. These results have the potential to uncover beta cell ER stress mitigation factors and add support to beta cell rest strategies to preserve function.
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Affiliation(s)
| | | | | | | | - Luiz F Barella
- Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Fiona Armoo
- Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Melissa K McCoy
- Departments of Biochemistry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Andy V Huynh
- Departments of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jonathan Z Yang
- Departments of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bruce A Posner
- Departments of Biochemistry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Melanie H Cobb
- Departments of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Michael A Kalwat
- Correspondence: Michael A. Kalwat, PhD, Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, 1210 Waterway Blvd Ste, 2000 Indianapolis, IN 46202, USA. or
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18
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Abstract
The ability to maintain normoglycaemia, through glucose-sensitive insulin release, is a key aspect of postnatal beta cell function. However, terminally differentiated beta cell identity does not necessarily imply functional maturity. Beta cell maturation is therefore a continuation of beta cell development, albeit a process that occurs postnatally in mammals. Although many important features have been identified in the study of beta cell maturation, as of yet no unified mechanistic model of beta cell functional maturity exists. Here, we review recent findings about the underlying mechanisms of beta cell functional maturation. These findings include systemic hormonal and nutritional triggers that operate through energy-sensing machinery shifts within beta cells, resulting in primed metabolic states that allow for appropriate glucose trafficking and, ultimately, insulin release. We also draw attention to the expansive synergistic nature of these pathways and emphasise that beta cell maturation is dependent on overlapping regulatory and metabolic networks.
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Affiliation(s)
- Tom Barsby
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
| | - Timo Otonkoski
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
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19
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Morriseau TS, Doucette CA, Dolinsky VW. More than meets the islet: aligning nutrient and paracrine inputs with hormone secretion in health and disease. Am J Physiol Endocrinol Metab 2022; 322:E446-E463. [PMID: 35373587 DOI: 10.1152/ajpendo.00411.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pancreatic islet is responsive to an array of endocrine, paracrine, and nutritional inputs that adjust hormone secretion to ensure accurate control of glucose homeostasis. Although the mechanisms governing glucose-coupled insulin secretion have received the most attention, there is emerging evidence for a multitude of physiological signaling pathways and paracrine networks that collectively regulate insulin, glucagon, and somatostatin release. Moreover, the modulation of these pathways in conditions of glucotoxicity or lipotoxicity are areas of both growing interest and controversy. In this review, the contributions of external, intrinsic, and paracrine factors in pancreatic β-, α-, and δ-cell secretion across the full spectrum of physiological (i.e., fasting and fed) and pathophysiological (gluco- and lipotoxicity; diabetes) environments will be critically discussed.
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Affiliation(s)
- Taylor S Morriseau
- Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Christine A Doucette
- Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Vernon W Dolinsky
- Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
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20
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Ježek P, Holendová B, Jabůrek M, Dlasková A, Plecitá-Hlavatá L. Contribution of Mitochondria to Insulin Secretion by Various Secretagogues. Antioxid Redox Signal 2022; 36:920-952. [PMID: 34180254 PMCID: PMC9125579 DOI: 10.1089/ars.2021.0113] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Significance: Mitochondria determine glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells by elevating ATP synthesis. As the metabolic and redox hub, mitochondria provide numerous links to the plasma membrane channels, insulin granule vesicles (IGVs), cell redox, NADH, NADPH, and Ca2+ homeostasis, all affecting insulin secretion. Recent Advances: Mitochondrial redox signaling was implicated in several modes of insulin secretion (branched-chain ketoacid [BCKA]-, fatty acid [FA]-stimulated). Mitochondrial Ca2+ influx was found to enhance GSIS, reflecting cytosolic Ca2+ oscillations induced by action potential spikes (intermittent opening of voltage-dependent Ca2+ and K+ channels) or the superimposed Ca2+ release from the endoplasmic reticulum (ER). The ATPase inhibitory factor 1 (IF1) was reported to tune the glucose sensitivity range for GSIS. Mitochondrial protein kinase A was implicated in preventing the IF1-mediated inhibition of the ATP synthase. Critical Issues: It is unknown how the redox signal spreads up to the plasma membrane and what its targets are, what the differences in metabolic, redox, NADH/NADPH, and Ca2+ signaling, and homeostasis are between the first and second GSIS phase, and whether mitochondria can replace ER in the amplification of IGV exocytosis. Future Directions: Metabolomics studies performed to distinguish between the mitochondrial matrix and cytosolic metabolites will elucidate further details. Identifying the targets of cell signaling into mitochondria and of mitochondrial retrograde metabolic and redox signals to the cell will uncover further molecular mechanisms for insulin secretion stimulated by glucose, BCKAs, and FAs, and the amplification of secretion by glucagon-like peptide (GLP-1) and metabotropic receptors. They will identify the distinction between the hub β-cells and their followers in intact and diabetic states. Antioxid. Redox Signal. 36, 920-952.
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Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Blanka Holendová
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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21
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Wang X, Luo X. Precursor Quantitation Methods for Next Generation Food Production. Front Bioeng Biotechnol 2022; 10:849177. [PMID: 35360389 PMCID: PMC8960114 DOI: 10.3389/fbioe.2022.849177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 02/22/2022] [Indexed: 11/21/2022] Open
Abstract
Food is essential for human survival. Nowadays, traditional agriculture faces challenges in balancing the need of sustainable environmental development and the rising food demand caused by an increasing population. In addition, in the emerging of consumers' awareness of health related issues bring a growing trend towards novel nature-based food additives. Synthetic biology, using engineered microbial cell factories for production of various molecules, shows great advantages for generating food alternatives and additives, which not only relieve the pressure laid on tradition agriculture, but also create a new stage in healthy and sustainable food supplement. The biosynthesis of food components (protein, fats, carbohydrates or vitamins) in engineered microbial cells often involves cellular central metabolic pathways, where common precursors are processed into different proteins and products. Quantitation of the precursors provides information of the metabolic flux and intracellular metabolic state, giving guidance for precise pathway engineering. In this review, we summarized the quantitation methods for most cellular biosynthetic precursors, including energy molecules and co-factors involved in redox-reactions. It will also be useful for studies worked on pathway engineering of other microbial-derived metabolites. Finally, advantages and limitations of each method are discussed.
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Affiliation(s)
- Xinran Wang
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Xiaozhou Luo
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- Shenzhen Institute of Advanced Technology, Shenzhen, China
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22
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Rohli KE, Boyer CK, Blom SE, Stephens SB. Nutrient Regulation of Pancreatic Islet β-Cell Secretory Capacity and Insulin Production. Biomolecules 2022; 12:335. [PMID: 35204835 PMCID: PMC8869698 DOI: 10.3390/biom12020335] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 01/27/2023] Open
Abstract
Pancreatic islet β-cells exhibit tremendous plasticity for secretory adaptations that coordinate insulin production and release with nutritional demands. This essential feature of the β-cell can allow for compensatory changes that increase secretory output to overcome insulin resistance early in Type 2 diabetes (T2D). Nutrient-stimulated increases in proinsulin biosynthesis may initiate this β-cell adaptive compensation; however, the molecular regulators of secretory expansion that accommodate the increased biosynthetic burden of packaging and producing additional insulin granules, such as enhanced ER and Golgi functions, remain poorly defined. As these adaptive mechanisms fail and T2D progresses, the β-cell succumbs to metabolic defects resulting in alterations to glucose metabolism and a decline in nutrient-regulated secretory functions, including impaired proinsulin processing and a deficit in mature insulin-containing secretory granules. In this review, we will discuss how the adaptative plasticity of the pancreatic islet β-cell's secretory program allows insulin production to be carefully matched with nutrient availability and peripheral cues for insulin signaling. Furthermore, we will highlight potential defects in the secretory pathway that limit or delay insulin granule biosynthesis, which may contribute to the decline in β-cell function during the pathogenesis of T2D.
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Affiliation(s)
- Kristen E. Rohli
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Cierra K. Boyer
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Sandra E. Blom
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Samuel B. Stephens
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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23
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Glucose-6-phosphatase catalytic subunit 2 negatively regulates glucose oxidation and insulin secretion in pancreatic β-cells. J Biol Chem 2022; 298:101729. [PMID: 35176280 PMCID: PMC8941207 DOI: 10.1016/j.jbc.2022.101729] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 12/11/2022] Open
Abstract
Elevated fasting blood glucose (FBG) is associated with increased risks of developing type 2 diabetes (T2D) and cardiovascular-associated mortality. G6PC2 is predominantly expressed in islets, encodes a glucose-6-phosphatase catalytic subunit that converts glucose-6-phosphate (G6P) to glucose, and has been linked with variations in FBG in genome-wide association studies. Deletion of G6pc2 in mice has been shown to lower FBG without affecting fasting plasma insulin levels in vivo. At 5 mM glucose, pancreatic islets from G6pc2 knockout (KO) mice exhibit no glucose cycling, increased glycolytic flux, and enhanced glucose-stimulated insulin secretion (GSIS). However, the broader effects of G6pc2 KO on β-cell metabolism and redox regulation are unknown. Here we used CRISPR/Cas9 gene editing and metabolic flux analysis in βTC3 cells, a murine pancreatic β-cell line, to examine the role of G6pc2 in regulating glycolytic and mitochondrial fluxes. We found that deletion of G6pc2 led to ∼60% increases in glycolytic and citric acid cycle (CAC) fluxes at both 5 and 11 mM glucose concentrations. Furthermore, intracellular insulin content and GSIS were enhanced by approximately two-fold, along with increased cytosolic redox potential and reductive carboxylation flux. Normalization of fluxes relative to net glucose uptake revealed upregulation in two NADPH-producing pathways in the CAC. These results demonstrate that G6pc2 regulates GSIS by modulating not only glycolysis but also, independently, citric acid cycle activity in β-cells. Overall, our findings implicate G6PC2 as a potential therapeutic target for enhancing insulin secretion and lowering FBG, which could benefit individuals with prediabetes, T2D, and obesity.
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24
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Newsholme P, Rowlands J, Rose’Meyer R, Cruzat V. Metabolic Adaptions/Reprogramming in Islet Beta-Cells in Response to Physiological Stimulators—What Are the Consequences. Antioxidants (Basel) 2022; 11:antiox11010108. [PMID: 35052612 PMCID: PMC8773416 DOI: 10.3390/antiox11010108] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/25/2022] Open
Abstract
Irreversible pancreatic β-cell damage may be a result of chronic exposure to supraphysiological glucose or lipid concentrations or chronic exposure to therapeutic anti-diabetic drugs. The β-cells are able to respond to blood glucose in a narrow concentration range and release insulin in response, following activation of metabolic pathways such as glycolysis and the TCA cycle. The β-cell cannot protect itself from glucose toxicity by blocking glucose uptake, but indeed relies on alternative metabolic protection mechanisms to avoid dysfunction and death. Alteration of normal metabolic pathway function occurs as a counter regulatory response to high nutrient, inflammatory factor, hormone or therapeutic drug concentrations. Metabolic reprogramming is a term widely used to describe a change in regulation of various metabolic enzymes and transporters, usually associated with cell growth and proliferation and may involve reshaping epigenetic responses, in particular the acetylation and methylation of histone proteins and DNA. Other metabolic modifications such as Malonylation, Succinylation, Hydroxybutyrylation, ADP-ribosylation, and Lactylation, may impact regulatory processes, many of which need to be investigated in detail to contribute to current advances in metabolism. By describing multiple mechanisms of metabolic adaption that are available to the β-cell across its lifespan, we hope to identify sites for metabolic reprogramming mechanisms, most of which are incompletely described or understood. Many of these mechanisms are related to prominent antioxidant responses. Here, we have attempted to describe the key β-cell metabolic adaptions and changes which are required for survival and function in various physiological, pathological and pharmacological conditions.
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Affiliation(s)
- Philip Newsholme
- Curtin Medical School and CHIRI, Curtin University, Perth, WA 6845, Australia
- Correspondence: (P.N.); (J.R.)
| | - Jordan Rowlands
- Curtin Medical School and CHIRI, Curtin University, Perth, WA 6845, Australia
- Correspondence: (P.N.); (J.R.)
| | - Roselyn Rose’Meyer
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Vinicius Cruzat
- Faculty of Health, Torrens University Australia, Brisbane, QLD 4006, Australia;
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Close AF, Chae H, Jonas JC. The lack of functional nicotinamide nucleotide transhydrogenase only moderately contributes to the impairment of glucose tolerance and glucose-stimulated insulin secretion in C57BL/6J vs C57BL/6N mice. Diabetologia 2021; 64:2550-2561. [PMID: 34448880 DOI: 10.1007/s00125-021-05548-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 05/26/2021] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS Nicotinamide nucleotide transhydrogenase (NNT) is involved in mitochondrial NADPH production and its spontaneous inactivating mutation (NntTr [Tr, truncated]) is usually considered to be the main cause of the lower glucose tolerance of C57BL/6J vs C57BL/6N mice. However, the impact of this mutation on glucose tolerance remains disputed. Here, we singled out the impact of NntTr from that of other genetic variants between C57BL/6J and C57BL/6N mice on mitochondrial glutathione redox state (EGSH), glucose-stimulated insulin secretion (GSIS) and glucose tolerance. METHODS Male and female N5BL/6J mice that express wild-type Nnt (NntWT) or NntTr (N5-WT and N5-Tr mice) on the C57BL/6J genetic background were obtained by crossing N5BL/6J NntWT/Tr heterozygous mice. C57BL/6J and C57BL/6N mice were from Janvier Labs. The Nnt genotype was confirmed by PCR and the genetic background by whole genome sequencing of one mouse of each type. Glucose tolerance was assessed by IPGTT, ITT and fasting/refeeding tests. Stimulus-secretion coupling events and GSIS were measured in isolated pancreatic islets. Cytosolic and mitochondrial EGSH were measured using the fluorescent redox probe GRX1-roGFP2 (glutaredoxin 1 fused to redox-sensitive enhanced GFP). RESULTS The Nnt genotype and genetic background of each type of mouse were confirmed. As reported previously in C57BL/6N vs C57BL/6J islets, the glucose regulation of mitochondrial (but not cytosolic) EGSH and of NAD(P)H autofluorescence was markedly improved in N5-WT vs N5-Tr islets, confirming the role of NNT in mitochondrial redox regulation. However, ex vivo GSIS was only 1.2-1.4-times higher in N5-WT vs N5-Tr islets, while it was 2.4-times larger in C57BL/6N vs N5-WT islets, questioning the role of NNT in GSIS. In vivo, the ITT results did not differ between N5-WT and N5-Tr or C57BL/6N mice. However, the glucose excursion during an IPGTT was only 15-20% lower in female N5-WT mice than in N5-Tr and C57BL/6J mice and remained 3.5-times larger than in female C57BL/6N mice. Similar observations were made during a fasting/refeeding test. A slightly larger (~30%) impact of NNT on glucose tolerance was found in males. CONCLUSIONS/INTERPRETATION Although our results confirm the importance of NNT in the regulation of mitochondrial redox state by glucose, they markedly downsize the role of NNT in the alteration of GSIS and glucose tolerance in C57BL/6J vs C57BL/6N mice. Therefore, documenting an NntWT genotype in C57BL/6 mice does not provide proof that their glucose tolerance is as good as in C57BL/6N mice.
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Affiliation(s)
- Anne-Françoise Close
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Heeyoung Chae
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Jean-Christophe Jonas
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium.
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The Controversial Role of Glucose-6-Phosphate Dehydrogenase Deficiency on Cardiovascular Disease: A Narrative Review. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5529256. [PMID: 34007401 PMCID: PMC8110402 DOI: 10.1155/2021/5529256] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/27/2021] [Accepted: 04/21/2021] [Indexed: 12/12/2022]
Abstract
Cardiovascular disorders (CVD) are highly prevalent and the leading cause of death worldwide. Atherosclerosis is responsible for most cases of CVD. The plaque formation and subsequent thrombosis in atherosclerosis constitute an ongoing process that is influenced by numerous risk factors such as hypertension, diabetes, dyslipidemia, obesity, smoking, inflammation, and sedentary lifestyle. Among the various risk and protective factors, the role of glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common inborn enzyme disorder across populations, is still debated. For decades, it has been considered a protective factor against the development of CVD. However, in the recent years, growing scientific evidence has suggested that this inherited condition may act as a CVD risk factor. The role of G6PD deficiency in the atherogenic process has been investigated using in vitro or ex vivo cellular models, animal models, and epidemiological studies in human cohorts of variable size and across different ethnic groups, with conflicting results. In this review, the impact of G6PD deficiency on CVD was critically reconsidered, taking into account the most recent acquisitions on molecular and biochemical mechanisms, namely, antioxidative mechanisms, glutathione recycling, and nitric oxide production, as well as their mutual interactions, which may be impaired by the enzyme defect in the context of the pentose phosphate pathway. Overall, current evidence supports the notion that G6PD downregulation may favor the onset and evolution of atheroma in subjects at risk of CVD. Given the relatively high frequency of this enzyme deficiency in several regions of the world, this finding might be of practical importance to tailor surveillance guidelines and facilitate risk stratification.
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Muñoz-Prieto A, González-Arostegui LG, Rubić I, Cerón JJ, Tvarijonaviciute A, Horvatić A, Mrljak V. Untargeted metabolomic profiling of serum in dogs with hypothyroidism. Res Vet Sci 2021; 136:6-10. [PMID: 33550147 DOI: 10.1016/j.rvsc.2021.01.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 12/26/2020] [Accepted: 01/26/2021] [Indexed: 02/06/2023]
Abstract
Hypothyroidism is one of the most commonly diagnosed endocrine disease in dogs. The clinical signs are caused by a deficiency of the active thyroid hormones triiodothyronine (T3) and thyroxine (T4) and have a negative impact on dog's quality of life. We hypothesized that serum metabolic profile varies between healthy dogs and dogs with hypothyroidism. Twenty serum samples from dogs with hypothyroidism and 20 from healthy dogs were used for untargeted metabolomics analysis performed by LC/MS analysis. Fifteen metabolites showed significant changes between hypothyroid and healthy dogs, being the pentose phosphate pathway (PPP), aminoacyl-tRNA biosynthesis and pyrimidine metabolism the principal pathways altered in hypothyroidism. Specifically, metabolites such as D-gluconic acid and L-Isoleucine may potentially act as biomarkers of disease.
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Affiliation(s)
- Alberto Muñoz-Prieto
- Clinic for Internal Diseases, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb 10000, Croatia
| | - Luis Guillermo González-Arostegui
- Interdisciplinary Laboratory of Clinical Analysis, Interlab-UMU, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain
| | - Ivana Rubić
- Clinic for Internal Diseases, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb 10000, Croatia
| | - José Joaquín Cerón
- Interdisciplinary Laboratory of Clinical Analysis, Interlab-UMU, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain
| | - Asta Tvarijonaviciute
- Interdisciplinary Laboratory of Clinical Analysis, Interlab-UMU, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain.
| | - Anita Horvatić
- Department of Chemistry and Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
| | - Vladimir Mrljak
- Clinic for Internal Diseases, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb 10000, Croatia
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Ježek P, Holendová B, Jabůrek M, Tauber J, Dlasková A, Plecitá-Hlavatá L. The Pancreatic β-Cell: The Perfect Redox System. Antioxidants (Basel) 2021; 10:antiox10020197. [PMID: 33572903 PMCID: PMC7912581 DOI: 10.3390/antiox10020197] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β-cell insulin secretion, which responds to various secretagogues and hormonal regulations, is reviewed here, emphasizing the fundamental redox signaling by NADPH oxidase 4- (NOX4-) mediated H2O2 production for glucose-stimulated insulin secretion (GSIS). There is a logical summation that integrates both metabolic plus redox homeostasis because the ATP-sensitive K+ channel (KATP) can only be closed when both ATP and H2O2 are elevated. Otherwise ATP would block KATP, while H2O2 would activate any of the redox-sensitive nonspecific calcium channels (NSCCs), such as TRPM2. Notably, a 100%-closed KATP ensemble is insufficient to reach the -50 mV threshold plasma membrane depolarization required for the activation of voltage-dependent Ca2+ channels. Open synergic NSCCs or Cl- channels have to act simultaneously to reach this threshold. The resulting intermittent cytosolic Ca2+-increases lead to the pulsatile exocytosis of insulin granule vesicles (IGVs). The incretin (e.g., GLP-1) amplification of GSIS stems from receptor signaling leading to activating the phosphorylation of TRPM channels and effects on other channels to intensify integral Ca2+-influx (fortified by endoplasmic reticulum Ca2+). ATP plus H2O2 are also required for branched-chain ketoacids (BCKAs); and partly for fatty acids (FAs) to secrete insulin, while BCKA or FA β-oxidation provide redox signaling from mitochondria, which proceeds by H2O2 diffusion or hypothetical SH relay via peroxiredoxin "redox kiss" to target proteins.
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Campbell JE, Newgard CB. Mechanisms controlling pancreatic islet cell function in insulin secretion. Nat Rev Mol Cell Biol 2021; 22:142-158. [PMID: 33398164 DOI: 10.1038/s41580-020-00317-7] [Citation(s) in RCA: 255] [Impact Index Per Article: 85.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2020] [Indexed: 02/07/2023]
Abstract
Metabolic homeostasis in mammals is tightly regulated by the complementary actions of insulin and glucagon. The secretion of these hormones from pancreatic β-cells and α-cells, respectively, is controlled by metabolic, endocrine, and paracrine regulatory mechanisms and is essential for the control of blood levels of glucose. The deregulation of these mechanisms leads to various pathologies, most notably type 2 diabetes, which is driven by the combined lesions of impaired insulin action and a loss of the normal insulin secretion response to glucose. Glucose stimulates insulin secretion from β-cells in a bi-modal fashion, and new insights about the underlying mechanisms, particularly relating to the second or amplifying phase of this secretory response, have been recently gained. Other recent work highlights the importance of α-cell-produced proglucagon-derived peptides, incretin hormones from the gastrointestinal tract and other dietary components, including certain amino acids and fatty acids, in priming and potentiation of the β-cell glucose response. These advances provide a new perspective for the understanding of the β-cell failure that triggers type 2 diabetes.
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Affiliation(s)
- Jonathan E Campbell
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA.,Department of Medicine, Endocrinology and Metabolism Division, Duke University Medical Center, Durham, NC, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Christopher B Newgard
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA. .,Department of Medicine, Endocrinology and Metabolism Division, Duke University Medical Center, Durham, NC, USA. .,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA.
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Chareyron I, Christen S, Moco S, Valsesia A, Lassueur S, Dayon L, Wollheim CB, Santo Domingo J, Wiederkehr A. Augmented mitochondrial energy metabolism is an early response to chronic glucose stress in human pancreatic beta cells. Diabetologia 2020; 63:2628-2640. [PMID: 32960311 PMCID: PMC7641954 DOI: 10.1007/s00125-020-05275-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/04/2020] [Indexed: 01/15/2023]
Abstract
AIMS/HYPOTHESIS In islets from individuals with type 2 diabetes and in islets exposed to chronic elevated glucose, mitochondrial energy metabolism is impaired. Here, we studied early metabolic changes and mitochondrial adaptations in human beta cells during chronic glucose stress. METHODS Respiration and cytosolic ATP changes were measured in human islet cell clusters after culture for 4 days in 11.1 mmol/l glucose. Metabolomics was applied to analyse intracellular metabolite changes as a result of glucose stress conditions. Alterations in beta cell function were followed using insulin secretion assays or cytosolic calcium signalling after expression of the calcium probe YC3.6 specifically in beta cells of islet clusters. RESULTS At early stages of glucose stress, mitochondrial energy metabolism was augmented in contrast to the previously described mitochondrial dysfunction in beta cells from islets of diabetic donors. Following chronic glucose stress, mitochondrial respiration increased (by 52.4%, p < 0.001) and, as a consequence, the cytosolic ATP/ADP ratio in resting human pancreatic islet cells was elevated (by 27.8%, p < 0.05). Because of mitochondrial overactivation in the resting state, nutrient-induced beta cell activation was reduced. In addition, chronic glucose stress caused metabolic adaptations that resulted in the accumulation of intermediates of the glycolytic pathway, the pentose phosphate pathway and the TCA cycle; the most strongly augmented metabolite was glycerol 3-phosphate. The changes in metabolites observed are likely to be due to the inability of mitochondria to cope with continuous nutrient oversupply. To protect beta cells from chronic glucose stress, we inhibited mitochondrial pyruvate transport. Metabolite concentrations were partially normalised and the mitochondrial respiratory response to nutrients was markedly improved. Furthermore, stimulus-secretion coupling as assessed by cytosolic calcium signalling, was restored. CONCLUSION/INTERPRETATION We propose that metabolic changes and associated mitochondrial overactivation are early adaptations to glucose stress, and may reflect what happens as a result of poor blood glucose control. Inhibition of mitochondrial pyruvate transport reduces mitochondrial nutrient overload and allows beta cells to recover from chronic glucose stress. Graphical abstract.
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Affiliation(s)
- Isabelle Chareyron
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
- Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Stefan Christen
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Sofia Moco
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Armand Valsesia
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Steve Lassueur
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Loïc Dayon
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
- Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Claes B Wollheim
- Department of Cell Physiology and Metabolism, University Medical Center, Geneva, Switzerland
| | - Jaime Santo Domingo
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Andreas Wiederkehr
- Nestlé Institute of Health Sciences, Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland.
- Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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Aghelan Z, Kiani S, Nasiri A, Sadeghi M, Farrokhi A, Khodarahmi R. Factors Influencing Mitochondrial Function as a Key Mediator of Glucose-Induced Insulin Release: Highlighting Nicotinamide Nucleotide Transhydrogenase. INTERNATIONAL JOURNAL OF MOLECULAR AND CELLULAR MEDICINE 2020; 9:107-122. [PMID: 32934948 PMCID: PMC7489113 DOI: 10.22088/ijmcm.bums.9.2.107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 08/04/2020] [Indexed: 12/13/2022]
Abstract
Pancreatic β-cells recognize blood glucose changes and release insulin that is a peptide hormone responsible for stable glycemia. Diabetes, a chronic disorder of insulin insufficiency, leads to disturbed glucose homeostasis and multi-organ problems. Glucose and insulin are key markers in the follow-up and control of this disease. Mitochondrial metabolism of pancreatic beta cells is a crucial part of glucose-stimulated cascade of insulin secretion. Effective factors on β-cells mitochondrial function in production of compounds such as tricarboxylic acid intermediates, glutamate, nicotinamide adenine dinucleotide phosphate, and reactive oxygen species can have great effects on the secretion of insulin under diabetes. This review enhances our knowledge of factors influencing mitochondrial function as a key mediator of glucose-induced insulin release that accordingly will be helpful to further our understanding of the mechanisms implicated in the progressive beta cell failure that results in diabetes.
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Affiliation(s)
- Zahra Aghelan
- Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Sara Kiani
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Abolfazl Nasiri
- Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Masoud Sadeghi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Alireza Farrokhi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Reza Khodarahmi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Li YY, Douillet C, Huang M, Beck R, Sumner SJ, Styblo M. Exposure to inorganic arsenic and its methylated metabolites alters metabolomics profiles in INS-1 832/13 insulinoma cells and isolated pancreatic islets. Arch Toxicol 2020; 94:1955-1972. [PMID: 32277266 PMCID: PMC8711643 DOI: 10.1007/s00204-020-02729-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/26/2020] [Indexed: 12/17/2022]
Abstract
Inorganic arsenic (iAs) is an environmental diabetogen, but mechanisms underlying its diabetogenic effects are poorly understood. Exposures to arsenite (iAsIII) and its methylated metabolites, methylarsonite (MAsIII) and dimethylarsinite (DMAsIII), have been shown to inhibit glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells and isolated pancreatic islets. GSIS is regulated by complex mechanisms. Increase in ATP production through metabolism of glucose and other substrates is the ultimate trigger for GSIS in β-cells. In the present study, we used metabolomics to identify metabolites and pathways perturbed in cultured INS-1 832/13 rat insulinoma cells and isolated murine pancreatic islets by exposures to iAsIII, MAsIII and DMAsIII. We found that the exposures perturbed multiple metabolites, which were enriched primarily in the pathways of amino acid, carbohydrate, phospholipid and carnitine metabolism. However, the effects of arsenicals in INS-1 832/13 cells differed from those in the islets and were exposure specific with very few overlaps between the three arsenicals. In INS-1 832/13 cells, all three arsenicals decreased succinate, a metabolite of Krebs cycle, which provides substrates for ATP synthesis in mitochondria. Acetylcarnitine was decreased consistently by exposures to arsenicals in both the cells and the islets. Acetylcarnitine is usually found in equilibrium with acetyl-CoA, which is the central metabolite in the catabolism of macronutrients and the key substrate for Krebs cycle. It is also thought to play an antioxidant function in mitochondria. Thus, while each of the three trivalent arsenicals perturbed specific metabolic pathways, which may or may not be associated with GSIS, all three arsenicals appeared to impair mechanisms that support ATP production or antioxidant defense in mitochondria. These results suggest that impaired ATP production and/or mitochondrial dysfunction caused by oxidative stress may be the mechanisms underlying the inhibition of GSIS in β-cells exposed to trivalent arsenicals.
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Affiliation(s)
- Yuan-Yuan Li
- Department of Nutrition, Nutrition Research Institute, CB# 74612, University of North Carolina at Chapel Hill School of Public Health, Chapel Hill, NC, 27599-7461, USA
- Department of Nutrition, CB# 74612, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, 27599-7461, USA
| | - Christelle Douillet
- Department of Nutrition, CB# 74612, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, 27599-7461, USA
| | - Madelyn Huang
- Curriculum in Toxicology and Environmental Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
- National Toxicology Program, National Institute of Environmental Health Science, Research Triangle Park, NC, USA
| | - Rowan Beck
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Susan Jenkins Sumner
- Department of Nutrition, Nutrition Research Institute, CB# 74612, University of North Carolina at Chapel Hill School of Public Health, Chapel Hill, NC, 27599-7461, USA.
- Department of Nutrition, CB# 74612, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, 27599-7461, USA.
| | - Miroslav Styblo
- Department of Nutrition, CB# 74612, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, 27599-7461, USA.
- Curriculum in Toxicology and Environmental Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA.
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Wu Y, Bible PW, Long S, Ming WK, Ding W, Long Y, Wen X, Li X, Deng X, Deng Y, Guo S, Doçi CL, Wei L, Chen H, Wang Z. Metagenomic analysis reveals gestational diabetes mellitus-related microbial regulators of glucose tolerance. Acta Diabetol 2020; 57:569-581. [PMID: 31820107 DOI: 10.1007/s00592-019-01434-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 10/09/2019] [Indexed: 12/14/2022]
Abstract
AIMS Recent studies have suggested a possible association between microbiota and gestational diabetes (GDM). However, the results are inconsistent. Our objective was to investigate further the relationship between GDM and microbiota and verify the potential microbial marker. METHODS Two complementary approaches were used for the demonstration. First, we compared the gut microbial composition of 23 GDM patients and 26 non-GDM ethnically Chinese Han pregnant women, by using whole-metagenome shotgun sequencing of their stool samples collected at the third trimester. Second, we used Q-PCR (quantitative polymerase chain reaction) to evaluate the gut microbial composition in the stool samples from another cohort of 150 Chinese pregnant women (113 Control and 37 GDM), to further confirm the potential microbial marker. RESULTS The gut microbiota of GDM women show lower albeit not statistically significant (p = 0.18) alpha diversity at the species level than non-GDM women. However, the species-level beta-diversity or between-sample diversity measured by Bray-Curtis distance shows significant differences (p < 2.2e-16) between the two groups. The species Bacteroides dorei positively correlated with both OGTT (oral glucose tolerance test) 0-Hour (p = 0.0099) and OGTT 1-Hour (p = 0.0070). There is a similar trend between Bacteroides sp. 3_1_33FAA and both OGTT 0-Hour (p = 0.014) and OGTT 1-Hour (p = 0.0101) response variables. The species Alistipes putredinis negatively correlated with OGTT 1-Hour (p = 0.0172) and OGTT 2-Hour (p = 0.0147). Q-PCR validation further confirmed the association between the glucose tolerance loci of Bacteroides dorei and OGTT response. CONCLUSIONS Gut microbiome is related to the diabetic status of Chinese women during pregnancy. Specific species such as Bacteroides dorei associate with glucose response and could be potential monitoring and therapeutic microbial markers for GDM.
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Affiliation(s)
- Yanxin Wu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China
| | - Paul W Bible
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China
- College of Arts and Sciences, Marian University, Indianapolis, IN, USA
| | - Sizhe Long
- Statistics Section, Center for Information Technology and Statistics, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, People's Republic of China
| | - Wai-Kit Ming
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China
| | - Wenjing Ding
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China
| | - Yuhang Long
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China
| | - Xiaofeng Wen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China
| | - Xifang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China
| | - Xiuli Deng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China
| | - Yuhua Deng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China
| | - Shixin Guo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China
| | - Colleen L Doçi
- College of Arts and Sciences, Marian University, Indianapolis, IN, USA
| | - Lai Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, People's Republic of China.
| | - Haitian Chen
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China.
| | - Zilian Wang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, People's Republic of China.
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Metabolomics Analysis of Nutrient Metabolism in β-Cells. J Mol Biol 2020; 432:1429-1445. [DOI: 10.1016/j.jmb.2019.07.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/03/2019] [Accepted: 07/11/2019] [Indexed: 01/05/2023]
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Cherkas A, Holota S, Mdzinarashvili T, Gabbianelli R, Zarkovic N. Glucose as a Major Antioxidant: When, What for and Why It Fails? Antioxidants (Basel) 2020; 9:antiox9020140. [PMID: 32033390 PMCID: PMC7070274 DOI: 10.3390/antiox9020140] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023] Open
Abstract
A human organism depends on stable glucose blood levels in order to maintain its metabolic needs. Glucose is considered to be the most important energy source, and glycolysis is postulated as a backbone pathway. However, when the glucose supply is limited, ketone bodies and amino acids can be used to produce enough ATP. In contrast, for the functioning of the pentose phosphate pathway (PPP) glucose is essential and cannot be substituted by other metabolites. The PPP generates and maintains the levels of nicotinamide adenine dinucleotide phosphate (NADPH) needed for the reduction in oxidized glutathione and protein thiols, the synthesis of lipids and DNA as well as for xenobiotic detoxification, regulatory redox signaling and counteracting infections. The flux of glucose into a PPP—particularly under extreme oxidative and toxic challenges—is critical for survival, whereas the glycolytic pathway is primarily activated when glucose is abundant, and there is lack of NADP+ that is required for the activation of glucose-6 phosphate dehydrogenase. An important role of glycogen stores in resistance to oxidative challenges is discussed. Current evidences explain the disruptive metabolic effects and detrimental health consequences of chronic nutritional carbohydrate overload, and provide new insights into the positive metabolic effects of intermittent fasting, caloric restriction, exercise, and ketogenic diet through modulation of redox homeostasis.
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Affiliation(s)
- Andriy Cherkas
- Department of Internal Medicine # 1, Lviv National Medical University, 79010 Lviv, Ukraine
- Correspondence:
| | - Serhii Holota
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Lviv National Medical University, 79010 Lviv, Ukraine;
- Department of Organic Chemistry and Pharmacy, Lesya Ukrainka Eastern European National University, 43025 Lutsk, Ukraine
| | - Tamaz Mdzinarashvili
- Institute of Medical and Applied Biophysics, I. Javakhishvili Tbilisi State University, 0128 Tbilisi, Georgia;
| | - Rosita Gabbianelli
- Unit of Molecular Biology, School of Pharmacy, University of Camerino, 62032 Camerino, Italy;
| | - Neven Zarkovic
- Laboratory for Oxidative Stress (LabOS), Institute “Rudjer Boskovic”, HR-10000 Zagreb, Croatia;
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36
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Teixeira CJ, Veras K, de Oliveira Carvalho CR. Dehydroepiandrosterone on metabolism and the cardiovascular system in the postmenopausal period. J Mol Med (Berl) 2020; 98:39-57. [PMID: 31713639 DOI: 10.1007/s00109-019-01842-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/16/2019] [Accepted: 10/09/2019] [Indexed: 12/16/2022]
Abstract
Dehydroepiandrosterone (DHEA), mostly present as its sulfated ester (DHEA-S), is an anabolic hormone that naturally declines with age. Furthermore, it is the most abundant androgen and estrogen precursor in humans. Low plasma levels of DHEA have been strongly associated with obesity, insulin resistance, dyslipidemia, and high blood pressure, increasing the risk of cardiovascular disease. In this respect, DHEA could be regarded as a promising agent against metabolic syndrome (MetS) in postmenopausal women, since several age-related metabolic diseases are reported during aging. There are plenty of experimental evidences showing beneficial effects after DHEA therapy on carbohydrate and lipid metabolism, as well as cardiovascular health. However, its potential as a therapeutic agent appears to attract controversy, due to the lack of effects on some symptoms related to MetS. In this review, we examine the available literature regarding the impact of DHEA therapy on adiposity, glucose metabolism, and the cardiovascular system in the postmenopausal period. Both clinical studies and in vitro and in vivo experimental models were selected, and where possible, the main cellular mechanisms involved in DHEA therapy were discussed. Schematic representation showing some of the general effects observed after administration DHEA therapy on target tissues of energy metabolism and the cardiovascular system. ↑ represents an increase, ↓ represents a decrease, - represents a worsening and ↔ represents no change after DHEA therapy.
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Affiliation(s)
- Caio Jordão Teixeira
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, 105 Alexander Fleming St, Campinas, SP, 13083-881, Brazil
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, 1524 Prof. Lineu Prestes Ave., ICB 1, Sao Paulo, SP, 05508-900, Brazil
| | - Katherine Veras
- Department of Nutrition, University of Mogi das Cruzes, 200 Dr. Cândido X. A. Souza Ave., Sao Paulo, SP, 08780-911, Brazil
| | - Carla Roberta de Oliveira Carvalho
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, 1524 Prof. Lineu Prestes Ave., ICB 1, Sao Paulo, SP, 05508-900, Brazil.
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Ge T, Yang J, Zhou S, Wang Y, Li Y, Tong X. The Role of the Pentose Phosphate Pathway in Diabetes and Cancer. Front Endocrinol (Lausanne) 2020; 11:365. [PMID: 32582032 PMCID: PMC7296058 DOI: 10.3389/fendo.2020.00365] [Citation(s) in RCA: 207] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 05/11/2020] [Indexed: 12/14/2022] Open
Abstract
The pentose phosphate pathway (PPP) branches from glucose 6-phosphate (G6P), produces NADPH and ribose 5-phosphate (R5P), and shunts carbons back to the glycolytic or gluconeogenic pathway. The PPP has been demonstrated to be a major regulator for cellular reduction-oxidation (redox) homeostasis and biosynthesis. Enzymes in the PPP are reported to play important roles in many human diseases. In this review, we will discuss the role of the PPP in type 2 diabetes and cancer.
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Peterson BS, Campbell JE, Ilkayeva O, Grimsrud PA, Hirschey MD, Newgard CB. Remodeling of the Acetylproteome by SIRT3 Manipulation Fails to Affect Insulin Secretion or β Cell Metabolism in the Absence of Overnutrition. Cell Rep 2019; 24:209-223.e6. [PMID: 29972782 PMCID: PMC6093627 DOI: 10.1016/j.celrep.2018.05.088] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/10/2018] [Accepted: 05/25/2018] [Indexed: 12/19/2022] Open
Abstract
SIRT3 is a nicotinamide adenine dinucleotide (NAD+)- dependent mitochondrial protein deacetylase purported to influence metabolism through post-translational modification of metabolic enzymes. Fuel-stimulated insulin secretion, which involves mitochondrial metabolism, could be susceptible to SIRT3-mediated effects. We used CRISPR/Cas9 technology to manipulate SIRT3 expression in β cells, resulting in widespread SIRT3-dependent changes in acetylation of key metabolic enzymes but no appreciable changes in glucose- or pyruvate-stimulated insulin secretion or metabolomic profile during glucose stimulation. Moreover, these broad changes in the SIRT3-targeted acetylproteome did not affect responses to nutritional or ER stress. We also studied mice with global SIRT3 knockout fed either standard chow (STD) or high-fat and high-sucrose (HFHS) diets. Only when chronically fed HFHS diet do SIRT3 KO animals exhibit a modest reduction in insulin secretion. We conclude that broad changes in mitochondrial protein acetylation in response to manipulation of SIRT3 are not sufficient to cause changes in islet function or metabolism. Peterson et al. report that ablation of SIRT3 in 832/13 β cells dramatically alters the mitochondrial acetylproteome but does not affect insulin secretion, metabolomic profile, or β cell survival. Moreover, SIRT3 knockout causes a modest reduction in insulin secretion in mice fed a high-fat and high-sucrose but not a standard chow diet.
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Affiliation(s)
- Brett S Peterson
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, NC 27710, USA
| | - Olga Ilkayeva
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27701, USA
| | - Paul A Grimsrud
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27701, USA
| | - Matthew D Hirschey
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, NC 27710, USA
| | - Christopher B Newgard
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, NC 27710, USA.
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39
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Roma LP, Jonas JC. Nutrient Metabolism, Subcellular Redox State, and Oxidative Stress in Pancreatic Islets and β-Cells. J Mol Biol 2019; 432:1461-1493. [PMID: 31634466 DOI: 10.1016/j.jmb.2019.10.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/25/2019] [Accepted: 10/10/2019] [Indexed: 01/01/2023]
Abstract
Insulin-secreting pancreatic β-cells play a critical role in blood glucose homeostasis and the development of type 2 diabetes (T2D) in the context of insulin resistance. Based on data obtained at the whole cell level using poorly specific chemical probes, reactive oxygen species (ROS) such as superoxide and hydrogen peroxide have been proposed to contribute to the stimulation of insulin secretion by nutrients (positive role) and to the alterations of cell survival and secretory function in T2D (negative role). This raised the controversial hypothesis that any attempt to decrease β-cell oxidative stress and apoptosis in T2D would further impair insulin secretion. Over the last decade, the development of genetically-encoded redox probes that can be targeted to cellular compartments of interest and are specific of redox couples allowed the evaluation of short- and long-term effects of nutrients on β-cell redox changes at the subcellular level. The data indicated that the nutrient regulation of β-cell redox signaling and ROS toxicity is far more complex than previously thought and that the subcellular compartmentation of these processes cannot be neglected when evaluating the mechanisms of ROS production or the efficacy of antioxidant enzymes and antioxidant drugs under glucolipotoxic conditions and in T2D. In this review, we present what is currently known about the compartmentation of redox homeostatic systems and tools to investigate it. We then review data about the effects of nutrients on β-cell subcellular redox state under normal conditions and in the context of T2D and discuss challenges and opportunities in the field.
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Affiliation(s)
- Leticia P Roma
- Universität des Saarlandes, Biophysics Department, Center for Human and Molecular Biology, Kirbergerstrasse Building 48, 66421, Homburg/Saar, Germany
| | - Jean-Christophe Jonas
- Université Catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Avenue Hippocrate 55 (B1.55.06), B-1200 Brussels, Belgium.
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40
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Santo-Domingo J, Dayon L, Wiederkehr A. Protein Lysine Acetylation: Grease or Sand in the Gears of β-Cell Mitochondria? J Mol Biol 2019; 432:1446-1460. [PMID: 31628953 DOI: 10.1016/j.jmb.2019.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 02/06/2023]
Abstract
Mitochondria carry out many essential functions in metabolism. A central task is the oxidation of nutrients and the generation of ATP by oxidative phosphorylation. Mitochondrial metabolism needs to be tightly regulated for the cell to respond to changes in ATP demand and nutrient supply. Here, we review how protein lysine acetylation contributes to the regulation of mitochondrial metabolism in insulin target tissues and the insulin-secreting pancreatic β-cell. We summarize recent evidence showing that in pancreatic β-cells, lysine acetylation occurs on a large number of proteins involved in metabolism. Furthermore, we give a brief overview of the molecular mechanism that controls lysine acetylation dynamics. We propose that protein lysine acetylation is an important mechanism for the fine-tuning of mitochondrial activity in β-cells during normal physiology. In contrast, nutrient oversupply, oxidative stress, or inhibition of the mitochondrial deacetylase SIRT3 leads to protein lysine hyperacetylation, which impairs mitochondrial function. By perturbing mitochondrial activity in β-cells and insulin target tissues, protein lysine hyperacetylation may contribute to the development of type 2 diabetes.
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Affiliation(s)
- Jaime Santo-Domingo
- Mitochondrial Function, Nestlé Institute of Health Sciences, 1015 Lausanne, Switzerland
| | - Loïc Dayon
- Proteomics, Nestlé Institute of Health Sciences, 1015 Lausanne, Switzerland
| | - Andreas Wiederkehr
- Mitochondrial Function, Nestlé Institute of Health Sciences, 1015 Lausanne, Switzerland.
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41
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Haythorne E, Rohm M, van de Bunt M, Brereton MF, Tarasov AI, Blacker TS, Sachse G, Silva Dos Santos M, Terron Exposito R, Davis S, Baba O, Fischer R, Duchen MR, Rorsman P, MacRae JI, Ashcroft FM. Diabetes causes marked inhibition of mitochondrial metabolism in pancreatic β-cells. Nat Commun 2019; 10:2474. [PMID: 31171772 PMCID: PMC6554411 DOI: 10.1038/s41467-019-10189-x] [Citation(s) in RCA: 200] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 04/12/2019] [Indexed: 12/21/2022] Open
Abstract
Diabetes is a global health problem caused primarily by the inability of pancreatic β-cells to secrete adequate levels of insulin. The molecular mechanisms underlying the progressive failure of β-cells to respond to glucose in type-2 diabetes remain unresolved. Using a combination of transcriptomics and proteomics, we find significant dysregulation of major metabolic pathways in islets of diabetic βV59M mice, a non-obese, eulipidaemic diabetes model. Multiple genes/proteins involved in glycolysis/gluconeogenesis are upregulated, whereas those involved in oxidative phosphorylation are downregulated. In isolated islets, glucose-induced increases in NADH and ATP are impaired and both oxidative and glycolytic glucose metabolism are reduced. INS-1 β-cells cultured chronically at high glucose show similar changes in protein expression and reduced glucose-stimulated oxygen consumption: targeted metabolomics reveals impaired metabolism. These data indicate hyperglycaemia induces metabolic changes in β-cells that markedly reduce mitochondrial metabolism and ATP synthesis. We propose this underlies the progressive failure of β-cells in diabetes.
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Affiliation(s)
- Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | - Maria Rohm
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich, Neuherberg, 85764, Germany
| | - Martijn van de Bunt
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7EL, UK
- Department of Bioinformatics and Data Mining, Novo Nordisk A/S, Måløv, 2760, Denmark
| | - Melissa F Brereton
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | - Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7EL, UK
| | - Thomas S Blacker
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Gregor Sachse
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | | | - Raul Terron Exposito
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | - Simon Davis
- Discovery Proteomics Facility, Target Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Otto Baba
- Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima, 770-8504, Japan
| | - Roman Fischer
- Discovery Proteomics Facility, Target Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Michael R Duchen
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7EL, UK
- Metabolic Research, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Göteborg, Box 433, 40530, Göteborg, Sweden
| | - James I MacRae
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK.
- Metabolic Research, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Göteborg, Box 433, 40530, Göteborg, Sweden.
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42
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Yin J, Ren W, Chen S, Li Y, Han H, Gao J, Liu G, Wu X, Li T, Woo Kim S, Yin Y. Metabolic Regulation of Methionine Restriction in Diabetes. Mol Nutr Food Res 2018; 62:e1700951. [PMID: 29603632 DOI: 10.1002/mnfr.201700951] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 01/25/2018] [Indexed: 12/16/2022]
Abstract
Although the effects of dietary methionine restriction have been investigated in the physiology of aging and diseases related to oxidative stress, the relationship between methionine restriction (MR) and the development of metabolic disorders has not been explored extensively. This review summarizes studies of the possible involvement of dietary methionine restriction in improving insulin resistance, glucose homeostasis, oxidative stress, lipid metabolism, the pentose phosphate pathway (PPP), and inflammation, with an emphasis on the fibroblast growth factor 21 and protein phosphatase 2A signals and autophagy in diabetes. Diets deficient in methionine may be a useful nutritional strategy in patients with diabetes.
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Affiliation(s)
- Jie Yin
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, Institute of Subtropical Animal Nutrition and Feed, College of Animal Science, South China Agricultural University, Guangzhou, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,University of Chinese Academy of Sciences, Beijing, PR, China
| | - Wenkai Ren
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, Institute of Subtropical Animal Nutrition and Feed, College of Animal Science, South China Agricultural University, Guangzhou, China.,Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Joint International Research Laboratory of Agriculture and Agri-Product, Safety of Ministry of Education of China, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Shuai Chen
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,University of Chinese Academy of Sciences, Beijing, PR, China
| | - Yuying Li
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,University of Chinese Academy of Sciences, Beijing, PR, China
| | - Hui Han
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,University of Chinese Academy of Sciences, Beijing, PR, China
| | - Jing Gao
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,University of Chinese Academy of Sciences, Beijing, PR, China
| | - Gang Liu
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China
| | - Xin Wu
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,Hunan Co-Innovation Center of Animal Production Safety, Changsha, PR, China
| | - Tiejun Li
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,Hunan Co-Innovation Center of Animal Production Safety, Changsha, PR, China
| | - Sung Woo Kim
- Department of Animal Science, North Carolina State University, Raleigh, NC, USA
| | - Yulong Yin
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, Institute of Subtropical Animal Nutrition and Feed, College of Animal Science, South China Agricultural University, Guangzhou, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.,Hunan Co-Innovation Center of Animal Production Safety, Changsha, PR, China
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43
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Gerencser AA. Metabolic activation-driven mitochondrial hyperpolarization predicts insulin secretion in human pancreatic beta-cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:817-828. [PMID: 29886047 DOI: 10.1016/j.bbabio.2018.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/18/2018] [Accepted: 06/05/2018] [Indexed: 12/31/2022]
Abstract
Mitochondrial metabolism plays a central role in insulin secretion in pancreatic beta-cells. Generation of protonmotive force and ATP synthesis from glucose-originated pyruvate are critical steps in the canonical pathway of glucose-stimulated insulin secretion. Mitochondrial metabolism is intertwined with pathways that are thought to amplify insulin secretion with mechanisms distinct from the canonical pathway, and the relative importance of these two pathways is controversial. Here I show that glucose-induced mitochondrial membrane potential (MMP) hyperpolarization is necessary for, and predicts, the rate of insulin secretion in primary cultured human beta-cells. When glucose concentration is elevated, increased metabolism results in a substantial MMP hyperpolarization, as well as in increased rates of ATP synthesis and turnover marked by faster cell respiration. Using modular kinetic analysis I explored what properties of cellular energy metabolism enable a large glucose-induced change in MMP in human beta-cells. I found that an ATP-dependent pathway activates glucose or substrate oxidation, acting as a positive feedback in energy metabolism. This activation mechanism is essential for concomitant fast respiration and high MMP, and for a high magnitude glucose-induced MMP hyperpolarization and therefore for insulin secretion.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Image Analyst Software, 43 Nova Lane, Novato, CA 94945, United States.
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44
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Fex M, Nicholas LM, Vishnu N, Medina A, Sharoyko VV, Nicholls DG, Spégel P, Mulder H. The pathogenetic role of β-cell mitochondria in type 2 diabetes. J Endocrinol 2018; 236:R145-R159. [PMID: 29431147 DOI: 10.1530/joe-17-0367] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/15/2018] [Indexed: 12/17/2022]
Abstract
Mitochondrial metabolism is a major determinant of insulin secretion from pancreatic β-cells. Type 2 diabetes evolves when β-cells fail to release appropriate amounts of insulin in response to glucose. This results in hyperglycemia and metabolic dysregulation. Evidence has recently been mounting that mitochondrial dysfunction plays an important role in these processes. Monogenic dysfunction of mitochondria is a rare condition but causes a type 2 diabetes-like syndrome owing to β-cell failure. Here, we describe novel advances in research on mitochondrial dysfunction in the β-cell in type 2 diabetes, with a focus on human studies. Relevant studies in animal and cell models of the disease are described. Transcriptional and translational regulation in mitochondria are particularly emphasized. The role of metabolic enzymes and pathways and their impact on β-cell function in type 2 diabetes pathophysiology are discussed. The role of genetic variation in mitochondrial function leading to type 2 diabetes is highlighted. We argue that alterations in mitochondria may be a culprit in the pathogenetic processes culminating in type 2 diabetes.
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Affiliation(s)
- Malin Fex
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Lisa M Nicholas
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Neelanjan Vishnu
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Anya Medina
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Vladimir V Sharoyko
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
| | - David G Nicholls
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Peter Spégel
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
- Department of ChemistryCenter for Analysis and Synthesis, Lund University, Sweden
| | - Hindrik Mulder
- Department of Clinical Sciences in MalmöUnit of Molecular Metabolism, Lund University Diabetes Centre, Clinical Research Center, Malmö University Hospital, Lund University, Malmö, Sweden
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45
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Andersson LE, Shcherbina L, Al-Majdoub M, Vishnu N, Arroyo CB, Aste Carrara J, Wollheim CB, Fex M, Mulder H, Wierup N, Spégel P. Glutamine-Elicited Secretion of Glucagon-Like Peptide 1 Is Governed by an Activated Glutamate Dehydrogenase. Diabetes 2018; 67:372-384. [PMID: 29229616 DOI: 10.2337/db16-1441] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 12/07/2017] [Indexed: 11/13/2022]
Abstract
Glucagon-like peptide 1 (GLP-1), secreted from intestinal L cells, glucose dependently stimulates insulin secretion from β-cells. This glucose dependence prevents hypoglycemia, rendering GLP-1 analogs a useful and safe treatment modality in type 2 diabetes. Although the amino acid glutamine is a potent elicitor of GLP-1 secretion, the responsible mechanism remains unclear. We investigated how GLP-1 secretion is metabolically coupled in L cells (GLUTag) and in vivo in mice using the insulin-secreting cell line INS-1 832/13 as reference. A membrane-permeable glutamate analog (dimethylglutamate [DMG]), acting downstream of electrogenic transporters, elicited similar alterations in metabolism as glutamine in both cell lines. Both DMG and glutamine alone elicited GLP-1 secretion in GLUTag cells and in vivo, whereas activation of glutamate dehydrogenase (GDH) was required to stimulate insulin secretion from INS-1 832/13 cells. Pharmacological inhibition in vivo of GDH blocked secretion of GLP-1 in response to DMG. In conclusion, our results suggest that nonelectrogenic nutrient uptake and metabolism play an important role in L cell stimulus-secretion coupling. Metabolism of glutamine and related analogs by GDH in the L cell may explain why GLP-1 secretion, but not that of insulin, is activated by these secretagogues in vivo.
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Affiliation(s)
- Lotta E Andersson
- Unit of Molecular Metabolism, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | - Liliya Shcherbina
- Neuroendocrine Cell Biology, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | - Mahmoud Al-Majdoub
- Unit of Molecular Metabolism, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | - Neelanjan Vishnu
- Unit of Molecular Metabolism, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | | | - Jonathan Aste Carrara
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Lund, Sweden
| | - Claes B Wollheim
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
- Department of Cell Physiology and Metabolism, University Medical Centre, Geneva, Switzerland
| | - Malin Fex
- Unit of Molecular Metabolism, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | - Hindrik Mulder
- Unit of Molecular Metabolism, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | - Nils Wierup
- Neuroendocrine Cell Biology, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
| | - Peter Spégel
- Unit of Molecular Metabolism, Department of Clinical Sciences, Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital, Malmö, Sweden
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Lund, Sweden
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46
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Montemurro C, Vadrevu S, Gurlo T, Butler AE, Vongbunyong KE, Petcherski A, Shirihai OS, Satin LS, Braas D, Butler PC, Tudzarova S. Cell cycle-related metabolism and mitochondrial dynamics in a replication-competent pancreatic beta-cell line. Cell Cycle 2017; 16:2086-2099. [PMID: 28820316 DOI: 10.1080/15384101.2017.1361069] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cell replication is a fundamental attribute of growth and repair in multicellular organisms. Pancreatic beta-cells in adults rarely enter cell cycle, hindering the capacity for regeneration in diabetes. Efforts to drive beta-cells into cell cycle have so far largely focused on regulatory molecules such as cyclins and cyclin-dependent kinases (CDKs). Investigations in cancer biology have uncovered that adaptive changes in metabolism, the mitochondrial network, and cellular Ca2+ are critical for permitting cells to progress through the cell cycle. Here, we investigated these parameters in the replication-competent beta-cell line INS 832/13. Cell cycle synchronization of this line permitted evaluation of cell metabolism, mitochondrial network, and cellular Ca2+ compartmentalization at key cell cycle stages. The mitochondrial network is interconnected and filamentous at G1/S but fragments during the S and G2/M phases, presumably to permit sorting to daughter cells. Pyruvate anaplerosis peaks at G1/S, consistent with generation of biomass for daughter cells, whereas mitochondrial Ca2+ and respiration increase during S and G2/M, consistent with increased energy requirements for DNA and lipid synthesis. This synchronization approach may be of value to investigators performing live cell imaging of Ca2+ or mitochondrial dynamics commonly undertaken in INS cell lines because without synchrony widely disparate data from cell to cell would be expected depending on position within cell cycle. Our findings also offer insight into why replicating beta-cells are relatively nonfunctional secreting insulin in response to glucose. They also provide guidance on metabolic requirements of beta-cells for the transition through the cell cycle that may complement the efforts currently restricted to manipulating cell cycle to drive beta-cells through cell cycle.
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Affiliation(s)
- Chiara Montemurro
- a Larry L. Hillblom Islet Research Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA
| | - Suryakiran Vadrevu
- b Department of Pharmacology and Brehm Diabetes Research Center , University of Michigan , Ann Arbor , MI , USA
| | - Tatyana Gurlo
- a Larry L. Hillblom Islet Research Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA
| | - Alexandra E Butler
- a Larry L. Hillblom Islet Research Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA
| | - Kenny E Vongbunyong
- a Larry L. Hillblom Islet Research Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA
| | - Anton Petcherski
- c Division of Endocrinology, Department of Medicine, David Geffen School of Medicine , University of California, Los Angeles , Los Angeles , CA , USA
| | - Orian S Shirihai
- c Division of Endocrinology, Department of Medicine, David Geffen School of Medicine , University of California, Los Angeles , Los Angeles , CA , USA
| | - Leslie S Satin
- b Department of Pharmacology and Brehm Diabetes Research Center , University of Michigan , Ann Arbor , MI , USA
| | - Daniel Braas
- d Department of Molecular and Medical Pharmacology, Crump Institute for Molecular Imaging , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA ; UCLA Metabolomics Center , University of California, Los Angeles , Los Angeles , CA , USA
| | - Peter C Butler
- a Larry L. Hillblom Islet Research Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA
| | - Slavica Tudzarova
- a Larry L. Hillblom Islet Research Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA.,e Jonsson Comprehensive Cancer Center , University of California, Los Angeles, David Geffen School of Medicine , Los Angeles , CA , USA
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47
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Jensen MV, Gooding J, Ferdaoussi M, Dai XQ, MacDonald PE, Newgard CB. Metabolomics applied to islet nutrient sensing mechanisms. Diabetes Obes Metab 2017; 19 Suppl 1:90-94. [PMID: 28880482 PMCID: PMC5929146 DOI: 10.1111/dom.13010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/09/2017] [Accepted: 05/12/2017] [Indexed: 12/16/2022]
Abstract
After multiple decades of investigation, the precise mechanisms involved in fuel-stimulated insulin secretion are still being revealed. One avenue for gaining deeper knowledge is to apply emergent tools of "metabolomics," involving mass spectrometry and nuclear magnetic resonance-based profiling of islet cells in their fuel-stimulated compared with basal states. The current article summarizes recent insights gained from application of metabolomics tools to the specific process of glucose-stimulated insulin secretion, revealing 2 new mechanisms that may provide targets for improving insulin secretion in diabetes.
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Affiliation(s)
- Mette V. Jensen
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701
| | - Jessica Gooding
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701
| | - Mourad Ferdaoussi
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada, T6G2R3
| | - Xiao-Qing Dai
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada, T6G2R3
| | - Patrick E. MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada, T6G2R3
| | - Christopher B. Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701
- Corresponding Author: Christopher B. Newgard, PhD, Duke Molecular Physiology Institute, 300 North Duke Street, Durham, NC 27701, , Phone: (919) 668-6059
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48
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Axelsson AS, Mahdi T, Nenonen HA, Singh T, Hänzelmann S, Wendt A, Bagge A, Reinbothe TM, Millstein J, Yang X, Zhang B, Gusmao EG, Shu L, Szabat M, Tang Y, Wang J, Salö S, Eliasson L, Artner I, Fex M, Johnson JD, Wollheim CB, Derry JMJ, Mecham B, Spégel P, Mulder H, Costa IG, Zhang E, Rosengren AH. Sox5 regulates beta-cell phenotype and is reduced in type 2 diabetes. Nat Commun 2017; 8:15652. [PMID: 28585545 PMCID: PMC5467166 DOI: 10.1038/ncomms15652] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 04/10/2017] [Indexed: 01/09/2023] Open
Abstract
Type 2 diabetes (T2D) is characterized by insulin resistance and impaired insulin secretion, but the mechanisms underlying insulin secretion failure are not completely understood. Here, we show that a set of co-expressed genes, which is enriched for genes with islet-selective open chromatin, is associated with T2D. These genes are perturbed in T2D and have a similar expression pattern to that of dedifferentiated islets. We identify Sox5 as a regulator of the module. Sox5 knockdown induces gene expression changes similar to those observed in T2D and diabetic animals and has profound effects on insulin secretion, including reduced depolarization-evoked Ca2+-influx and β-cell exocytosis. SOX5 overexpression reverses the expression perturbations observed in a mouse model of T2D, increases the expression of key β-cell genes and improves glucose-stimulated insulin secretion in human islets from donors with T2D. We suggest that human islets in T2D display changes reminiscent of dedifferentiation and highlight SOX5 as a regulator of β-cell phenotype and function.
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Affiliation(s)
- A S Axelsson
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - T Mahdi
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden.,Medical Research Center, Hawler Medical University, 44001 Erbil, Iraq
| | - H A Nenonen
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - T Singh
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - S Hänzelmann
- Institute of Biomedical Engineering, RWTH Aachen University Hospital, Pauwelstr 19, 52074 Aachen, Germany
| | - A Wendt
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - A Bagge
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - T M Reinbothe
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - J Millstein
- Sage Bionetworks, 1100 Fairview Avenue N, Seattle, Washington 98109, USA
| | - X Yang
- Sage Bionetworks, 1100 Fairview Avenue N, Seattle, Washington 98109, USA.,Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Dr East, Los Angeles, California 90095, USA
| | - B Zhang
- Sage Bionetworks, 1100 Fairview Avenue N, Seattle, Washington 98109, USA.,Department of Genetics and Genomic Sciences, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, New York 10029, USA
| | - E G Gusmao
- Institute of Biomedical Engineering, RWTH Aachen University Hospital, Pauwelstr 19, 52074 Aachen, Germany
| | - L Shu
- Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Dr East, Los Angeles, California 90095, USA
| | - M Szabat
- Diabetes Research Group, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 5358-2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Y Tang
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden.,Key Lab of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin 300070, China
| | - J Wang
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden.,Department of Emergency, Zhongshan Hospital, Xiamen University, Xiamen, Fujian 361004, China
| | - S Salö
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - L Eliasson
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - I Artner
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - M Fex
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - J D Johnson
- Diabetes Research Group, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 5358-2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - C B Wollheim
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden.,Department of Cell Physiology and Metabolism, University Medical Center, Rue Michel-Servet 1, 1206 Geneva, Switzerland
| | - J M J Derry
- Sage Bionetworks, 1100 Fairview Avenue N, Seattle, Washington 98109, USA
| | - B Mecham
- Trialomics, 6310 12th Avenue NE, Seattle, Washington 98115, USA
| | - P Spégel
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden.,Centre for Analysis and Synthesis, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden
| | - H Mulder
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - I G Costa
- Institute of Biomedical Engineering, RWTH Aachen University Hospital, Pauwelstr 19, 52074 Aachen, Germany
| | - E Zhang
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden
| | - A H Rosengren
- Lund University Diabetes Center, CRC 91-11 SUS, Jan Waldenströms gata 35, SE-20502 Malmö, Sweden.,Sage Bionetworks, 1100 Fairview Avenue N, Seattle, Washington 98109, USA.,Department of Neuroscience and Physiology, University of Gothenburg, Box 100, SE-405 30 Gothenburg, Sweden
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49
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Mulder H. Transcribing β-cell mitochondria in health and disease. Mol Metab 2017; 6:1040-1051. [PMID: 28951827 PMCID: PMC5605719 DOI: 10.1016/j.molmet.2017.05.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 05/13/2017] [Accepted: 05/22/2017] [Indexed: 12/17/2022] Open
Abstract
Background The recent genome-wide association studies (GWAS) of Type 2 Diabetes (T2D) have identified the pancreatic β-cell as the culprit in the pathogenesis of the disease. Mitochondrial metabolism plays a crucial role in the processes controlling release of insulin and β-cell mass. This notion implies that mechanisms controlling mitochondrial function have the potential to play a decisive pathogenetic role in T2D. Scope of the review This article reviews studies demonstrating that there is indeed mitochondrial dysfunction in islets in T2D, and that GWAS have identified a variant in the gene encoding transcription factor B1 mitochondrial (TFB1M), predisposing to T2D due to mitochondrial dysfunction and impaired insulin secretion. Mechanistic studies of the nature of this pathogenetic link, as well as of other mitochondrial transcription factors, are described. Major conclusions Based on this, it is argued that transcription and translation in mitochondria are critical processes determining mitochondrial function in β-cells in health and disease.
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Key Words
- AMPK, AMP-dependent protein kinase
- ATGL, adipocyte triglyceride lipase
- COX, Cytochrome c oxidase
- CYTB, Cytochrome b
- ERR-α, Estrogen-related receptor-α
- Expression quantitative trait locus (eQTL)
- GDH, Glutamate dehydrogenase
- GSIS, Glucose-stimulated insulin secretion
- GWAS, Genome-wide association study
- Genome-wide association study (GWAS)
- HSL, Hormone-sensitive lipase
- ICDc, Cytosolic isocitrate dehydrogenase
- Insulin secretion
- Islets
- KATP, ATP-dependent K+-channel
- MTERF, Mitochondrial transcription termination factor
- Mitochondria
- ND, NADH dehydrogenase
- NRF, Nuclear respiratory factor
- NSUN4, NOP2/Sun RNA methyltransferase family member 4
- OXPHOS, Oxidative phosphorylation
- PC, Pyruvate carboxylase
- PDH, pyruvate dehydrogenase
- PGC, Peroxisome proliferator-activated receptor-γ co-activator
- POLRMT, Mitochondrial RNA polymerase
- POLγ, DNA polymerase-γ
- PPARγ, Peroxisome proliferator-activated receptor-γ
- PRC, PGC1-related coactivator
- SENP1, Sentrin/SUMO-specific protease-1
- SNP, Single Nucleotide Polymorphism
- SUR1, Sulphonylurea receptor-1
- T2D, Type 2 Diabetes
- TCA, Tricarboxylic acid
- TEFM, Mitochondrial transcription elongation factor
- TFAM, Transcription factor A mitochondrial
- TFB1M, Transcription factor B1 mitochondrial
- TFB2M, Transcription factor B2 mitochondrial
- eQTL, Expression quantitative trait locus
- β-Cell
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Affiliation(s)
- Hindrik Mulder
- Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö, Sweden
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50
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Abstract
Pancreatic islet β cells secrete insulin in response to nutrient secretagogues, like glucose, dependent on calcium influx and nutrient metabolism. One of the most intriguing qualities of β cells is their ability to use metabolism to amplify the amount of secreted insulin independent of further alterations in intracellular calcium. Many years studying this amplifying process have shaped our current understanding of β cell stimulus-secretion coupling; yet, the exact mechanisms of amplification have been elusive. Recent studies utilizing metabolomics, computational modeling, and animal models have progressed our understanding of the metabolic amplifying pathway of insulin secretion from the β cell. New approaches will be discussed which offer in-roads to a more complete model of β cell function. The development of β cell therapeutics may be aided by such a model, facilitating the targeting of aspects of the metabolic amplifying pathway which are unique to the β cell.
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Affiliation(s)
- Michael A Kalwat
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States.
| | - Melanie H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
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