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Zhang X, Kupczyk E, Schmitt-Kopplin P, Mueller C. Current and future approaches for in vitro hit discovery in diabetes mellitus. Drug Discov Today 2022; 27:103331. [PMID: 35926826 DOI: 10.1016/j.drudis.2022.07.016] [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: 02/04/2022] [Revised: 06/10/2022] [Accepted: 07/26/2022] [Indexed: 12/15/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a serious public health problem. In this review, we discuss current and promising future drugs, targets, in vitro assays and emerging omics technologies in T2DM. Importantly, we open the perspective to image-based high-content screening (HCS), with the focus of combining it with metabolomics or lipidomics. HCS has become a strong technology in phenotypic screens because it allows comprehensive screening for the cell-modulatory activity of small molecules. Metabolomics and lipidomics screen for perturbations at the molecular level. The combination of these data-intensive comprehensive technologies is enabled by the rapid development of artificial intelligence. It promises a deep cellular and molecular phenotyping directly linked to chemical information about the applied drug candidates or complex mixtures.
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Affiliation(s)
- Xin Zhang
- Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany
| | - Erwin Kupczyk
- Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany; Comprehensive Foodomics Platform, Chair of Analytical Food Chemistry, TUM School of Life Sciences, Technical University of Munich, Maximus-von-Imhof-Forum 2, 85354 Freising, Germany
| | - Philippe Schmitt-Kopplin
- Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany; Comprehensive Foodomics Platform, Chair of Analytical Food Chemistry, TUM School of Life Sciences, Technical University of Munich, Maximus-von-Imhof-Forum 2, 85354 Freising, Germany.
| | - Constanze Mueller
- Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany.
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Jia JD, Jiang WG, Luo X, Li RR, Zhao YC, Tian G, Li YN. Vascular endothelial growth factor B inhibits insulin secretion in MIN6 cells and reduces Ca 2+ and cyclic adenosine monophosphate levels through PI3K/AKT pathway. World J Diabetes 2021; 12:480-498. [PMID: 33889292 PMCID: PMC8040075 DOI: 10.4239/wjd.v12.i4.480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/25/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Type 2 diabetes (T2D) is characterized by insufficient insulin secretion caused by defective pancreatic β-cell function or insulin resistance, resulting in an increase in blood glucose. However, the mechanism involved in this lack of insulin secretion is unclear. The level of vascular endothelial growth factor B (VEGF-B) is significantly increased in T2D patients. The inactivation of VEGF-B could restore insulin sensitivity in db/db mice by reducing fatty acid accumulation. It is speculated that VEGF-B is related to pancreatic β-cell dysfunction and is an important factor affecting β-cell secretion of insulin. As an in vitro model of normal pancreatic β-cells, the MIN6 cell line can be used to analyze the mechanism of insulin secretion and related biological effects.
AIM To study the role of VEGF-B in the insulin secretion signaling pathway in MIN6 cells and explore the effect of VEGF-B on blood glucose regulation.
METHODS The MIN6 mouse pancreatic islet β-cell line was used as the model system. By administering exogenous VEGF-B protein or knocking down VEGF-B expression in MIN6 cells, we examined the effects of VEGF-B on insulin secretion, Ca2+ and cyclic adenosine monophosphate (cAMP) levels, and the insulin secretion signaling pathway.
RESULTS Exogenous VEGF-B inhibited the secretion of insulin and simultaneously reduced the levels of Ca2+ and cAMP in MIN6 cells. Exogenous VEGF-B also reduced the expression of phospholipase C gamma 1 (PLCγ1), phosphatidylinositol 3-kinase (PI3K), serine/threonine kinase (AKT), and other proteins in the insulin secretion pathway. Upon knockdown of VEGF-B, MIN6 cells exhibited increased insulin secretion and Ca2+ and cAMP levels and upregulated expression of PLCγ1, PI3K, AKT, and other proteins.
CONCLUSION VEGF-B can regulate insulin secretion by modulating the levels of Ca2+ and cAMP. VEGF-B involvement in insulin secretion is related to the expression of PLCγ1, PI3K, AKT, and other signaling proteins. These results provide theoretical support and an experimental basis for the study of VEGF-B in the pathogenesis of T2D.
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Affiliation(s)
- Jing-Dan Jia
- Department of Pathophysiology, School of Basic Medicine, Binzhou Medical University, Yantai 264003, Shandong Province, China
| | - Wen-Guo Jiang
- Department of Pharmacy, Binzhou Medical University, Yantai 264003, Shandong Province, China
| | - Xu Luo
- Department of Pathophysiology, School of Basic Medicine, Binzhou Medical University, Yantai 264003, Shandong Province, China
| | - Rong-Rong Li
- Department of Pathophysiology, School of Basic Medicine, Binzhou Medical University, Yantai 264003, Shandong Province, China
| | - Yu-Chi Zhao
- Department of Surgery, Yantaishan Hospital, Yantai 264001, Shandong Province, China
| | - Geng Tian
- Department of Pharmacy, Binzhou Medical University, Yantai 264003, Shandong Province, China
| | - Ya-Na Li
- Department of Pathophysiology, School of Basic Medicine, Binzhou Medical University, Yantai 264003, Shandong Province, China
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Pillai RA, Islam MO, Selvam P, Sharma N, Chu AHY, Watkins OC, Godfrey KM, Lewis RM, Chan SY. Placental Inositol Reduced in Gestational Diabetes as Glucose Alters Inositol Transporters and IMPA1 Enzyme Expression. J Clin Endocrinol Metab 2021; 106:e875-e890. [PMID: 33165596 PMCID: PMC7116629 DOI: 10.1210/clinem/dgaa814] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Indexed: 02/08/2023]
Abstract
CONTEXT Perturbed inositol physiology in insulin-resistant conditions has led to proposals of inositol supplementation for gestational diabetes (GDM) prevention, but placental inositol biology is poorly understood. OBJECTIVE Investigate associations of maternal glycemia with placental inositol content, determine glucose effects on placental expression of inositol enzymes and transporters, and examine relations with birthweight. DESIGN AND PARTICIPANTS Case-control study of placentae from term singleton pregnancies (GDM n = 24, non-GDM n = 26), and culture of another 9 placentae in different concentrations of glucose and myo-inositol for 48 hours. MAIN OUTCOME MEASURES Placental inositol was quantified by the Megazyme assay. Relative expression of enzymes involved in myo-inositol metabolism and plasma membrane inositol transport was determined by quantitative RT-PCR and immunoblotting. Linear regression analyses were adjusted for maternal age, body mass index, ethnicity, gestational age, and sex. RESULTS Placental inositol content was 17% lower in GDM compared with non-GDM. Higher maternal mid-gestation glycemia were associated with lower placental inositol. Increasing fasting glycemia was associated with lower protein levels of the myo-inositol synthesis enzyme, IMPA1, and the inositol transporters, SLC5A11 and SLC2A13, the expression of which also correlated with placental inositol content. In vitro, higher glucose concentrations reduced IMPA1 and SLC5A11 mRNA expression. Increasing fasting glycemia positively associated with customized birthweight percentile as expected in cases with low placental inositol, but this association was attenuated with high placental inositol. CONCLUSION Glycemia-induced dysregulation of placental inositol synthesis and transport may be implicated in reduced placental inositol content in GDM, and this may in turn be permissive to accelerated fetal growth.
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Affiliation(s)
- Reshma A Pillai
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Mohammed O Islam
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Preben Selvam
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Neha Sharma
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Anne H Y Chu
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Oliver C Watkins
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Keith M Godfrey
- MRC Lifecourse Epidemiology Unit and NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Rohan M Lewis
- Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Shiao Y Chan
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
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Watkins OC, Yong HEJ, Sharma N, Chan SY. A review of the role of inositols in conditions of insulin dysregulation and in uncomplicated and pathological pregnancy. Crit Rev Food Sci Nutr 2020; 62:1626-1673. [PMID: 33280430 DOI: 10.1080/10408398.2020.1845604] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Inositols, a group of 6-carbon polyols, are highly bioactive molecules derived from diet and endogenous synthesis. Inositols and their derivatives are involved in glucose and lipid metabolism and participate in insulin-signaling, with perturbations in inositol processing being associated with conditions involving insulin resistance, dysglycemia and dyslipidemia such as polycystic ovary syndrome and diabetes. Pregnancy is similarly characterized by substantial and complex changes in glycemic and lipidomic regulation as part of maternal adaptation and is also associated with physiological alterations in inositol processing. Disruptions in maternal adaptation are postulated to have a critical pathophysiological role in pregnancy complications such as gestational diabetes and pre-eclampsia. Inositol supplementation has shown promise as an intervention for the alleviation of symptoms in conditions of insulin resistance and for gestational diabetes prevention. However, the mechanisms behind these affects are not fully understood. In this review, we explore the role of inositols in conditions of insulin dysregulation and in pregnancy, and identify priority areas for research. We particularly examine the role and function of inositols within the maternal-placental-fetal axis in both uncomplicated and pathological pregnancies. We also discuss how inositols may mediate maternal-placental-fetal cross-talk, and regulate fetal growth and development, and suggest that inositols play a vital role in promoting healthy pregnancy.
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Affiliation(s)
- Oliver C Watkins
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Hannah E J Yong
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore, Singapore
| | - Neha Sharma
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Shiao-Yng Chan
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore, Singapore
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5
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Parandeh F, Amisten S, Verma G, Mohammed Al-Amily I, Dunér P, Salehi A. Inhibitory effect of UDP-glucose on cAMP generation and insulin secretion. J Biol Chem 2020; 295:15245-15252. [PMID: 32855238 DOI: 10.1074/jbc.ra120.012929] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 08/21/2020] [Indexed: 12/27/2022] Open
Abstract
Type-2 diabetes (T2D) is a global disease caused by the inability of pancreatic β-cells to secrete adequate insulin. However, the molecular mechanisms underlying the failure of β-cells to respond to glucose in T2D remains unknown. Here, we investigated the relative contribution of UDP-glucose (UDP-G), a P2Y14-specific agonist, in the regulation of insulin release using human isolated pancreatic islets and INS-1 cells. P2Y14 was expressed in both human and rodent pancreatic β-cells. Dose-dependent activation of P2Y14 by UDP-G suppressed glucose-stimulated insulin secretion (GSIS) and knockdown of P2Y14 abolished the UDP-G effect. 12-h pretreatment of human islets with pertussis-toxin (PTX) improved GSIS and prevented the inhibitory effect of UDP-G on GSIS. UDP-G on GSIS suppression was associated with suppression of cAMP in INS-1 cells. UDP-G decreased the reductive capacity of nondiabetic human islets cultured at 5 mm glucose for 72 h and exacerbated the negative effect of 20 mm glucose on the cell viability during culture period. T2D donor islets displayed a lower reductive capacity when cultured at 5 mm glucose for 72 h that was further decreased in the presence of 20 mm glucose and UDP-G. Presence of a nonmetabolizable cAMP analog during culture period counteracted the effect of glucose and UDP-G. Islet cultures at 20 mm glucose increased apoptosis, which was further amplified when UDP-G was present. UDP-G modulated glucose-induced proliferation of INS-1 cells. The data provide intriguing evidence for P2Y14 and UDP-G's role in the regulation of pancreatic β-cell function.
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Affiliation(s)
- Fariborz Parandeh
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Stefan Amisten
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Gaurav Verma
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Israa Mohammed Al-Amily
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Pontus Dunér
- Experimental Cardiovascular Research Unit Clinical Research Centre, UMAS University of Lund, Malmö, Sweden
| | - Albert Salehi
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden.
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Li SYT, Cheng STW, Zhang D, Leung PS. Identification and Functional Implications of Sodium/ Myo-Inositol Cotransporter 1 in Pancreatic β-Cells and Type 2 Diabetes. Diabetes 2017; 66:1258-1271. [PMID: 28202581 DOI: 10.2337/db16-0880] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 02/07/2017] [Indexed: 11/13/2022]
Abstract
Myo-inositol (MI), the precursor of the second messenger phosphoinositide (PI), mediates multiple cellular events. Rat islets exhibit active transport of MI, although the mechanism involved remains elusive. Here, we report, for the first time, the expression of sodium/myo-inositol cotransporter 1 (SMIT1) in rat islets and, specifically, β-cells. Genetic or pharmacological inhibition of SMIT1 impaired glucose-stimulated insulin secretion by INS-1E cells, probably via downregulation of PI signaling. In addition, SMIT1 expression in INS-1E cells and isolated islets was augmented by acute high-glucose exposure and reduced in chronic hyperglycemia conditions. In corroboration, chronic MI treatment improved the disease phenotypes of diabetic rats and islets. On the basis of our results, we postulate that the MI transporter SMIT1 is required to maintain a stable PI pool in β-cells in order that PI remains available despite its rapid turnover.
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Affiliation(s)
- Stephen Yu Ting Li
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Sam Tsz Wai Cheng
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Dan Zhang
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Po Sing Leung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
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Santo-Domingo J, Chareyron I, Dayon L, Núñez Galindo A, Cominetti O, Pilar Giner Giménez M, De Marchi U, Canto C, Kussmann M, Wiederkehr A. Coordinated activation of mitochondrial respiration and exocytosis mediated by PKC signaling in pancreatic β cells. FASEB J 2016; 31:1028-1045. [PMID: 27927723 DOI: 10.1096/fj.201600837r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/22/2016] [Indexed: 12/17/2022]
Abstract
Mitochondria play a central role in pancreatic β-cell nutrient sensing by coupling their metabolism to plasma membrane excitability and insulin granule exocytosis. Whether non-nutrient secretagogues stimulate mitochondria as part of the molecular mechanism to promote insulin secretion is not known. Here, we show that PKC signaling, which is employed by many non-nutrient secretagogues, augments mitochondrial respiration in INS-1E (rat insulinoma cell line clone 1E) and human pancreatic β cells. The phorbol ester, phorbol 12-myristate 13-acetate, accelerates mitochondrial respiration at both resting and stimulatory glucose concentrations. A range of inhibitors of novel PKC isoforms prevent phorbol ester-induced respiration. Respiratory response was blocked by oligomycin that demonstrated PKC-dependent acceleration of mitochondrial ATP synthesis. Enhanced respiration was observed even when glycolysis was bypassed or fatty acid transport was blocked, which suggested that PKC regulates mitochondrial processes rather than upstream catabolic fluxes. A phosphoproteome study of phorbol ester-stimulated INS-1E cells maintained under resting (2.5 mM) glucose revealed a large number of phosphorylation sites that were altered during short-term activation of PKC signaling. The data set was enriched for proteins that are involved in gene expression, cytoskeleton remodeling, secretory vesicle transport, and exocytosis. Interactome analysis identified PKC, C-Raf, and ERK1/2 as the central phosphointeraction cluster. Prevention of ERK1/2 signaling by using a MEK1 inhibitor caused a marked decreased in phorbol 12-myristate 13-acetate-induced mitochondrial respiration. ERK1/2 signaling module therefore links PKC activation to downstream mitochondrial activation. We conclude that non-nutrient secretagogues act, in part, via PKC and downstream ERK1/2 signaling to stimulate mitochondrial energy production to compensate for energy expenditure that is linked to β-cell activation.-Santo-Domingo, J., Chareyron, I., Dayon, L., Galindo, A. N., Cominetti, O., Giménez, M. P. G., De Marchi, U., Canto, C., Kussmann, M., Wiederkehr, A. Coordinated activation of mitochondrial respiration and exocytosis mediated by PKC signaling in pancreatic β cells.
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Affiliation(s)
- Jaime Santo-Domingo
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Isabelle Chareyron
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Loïc Dayon
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Antonio Núñez Galindo
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Ornella Cominetti
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - María Pilar Giner Giménez
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Umberto De Marchi
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Carles Canto
- Diabetes and Metabolic Health, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Martin Kussmann
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Andreas Wiederkehr
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland;
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Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis. PLoS One 2016; 11:e0152869. [PMID: 27138453 PMCID: PMC4854486 DOI: 10.1371/journal.pone.0152869] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/21/2016] [Indexed: 12/17/2022] Open
Abstract
Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger pathway interactions will improve understanding of critical regulatory sites, how different GPCRs interact and pharmacological targets for modulating insulin secretion in type 2 diabetes.
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Jayanarayanan S, Anju TR, Smijin S, Paulose CS. Vitamin D3 supplementation increases insulin level by regulating altered IP3 and AMPA receptor expression in the pancreatic islets of streptozotocin-induced diabetic rat. J Nutr Biochem 2015; 26:1041-9. [PMID: 26054778 DOI: 10.1016/j.jnutbio.2015.04.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 04/13/2015] [Accepted: 04/26/2015] [Indexed: 12/17/2022]
Abstract
Pancreatic islets, particularly insulin-secreting β cells, share common characteristics with neurons. Glutamate is one of the major excitatory neurotransmitter in the brain and pancreas, and its action is mediated through glutamate receptors. In the present work, we analysed the role of vitamin D3 in the modulation of AMPA receptor subunit and their functional role in insulin release. Radio receptor binding study in diabetic rats showed a significant increase in AMPA receptor density. Insulin AMPA colabelling study showed an altered AMPA GluR2 and GluR4 subunit expression in the pancreatic beta cells. We also found lowered IP3 content and decreased IP3 receptor in pancreas of diabetic rats. The alterations in AMPA and IP3 receptor resulted in reduced cytosolic calcium level concentration, which further blocks Ca(2+)-mediated insulin release. Vitamin D3 supplementation restored the alteration in vitamin D receptor expression, AMPA receptor density and AMPA and IP3 receptor expression in the pancreatic islets that helps to restore the calcium-mediated insulin secretion. Our study reveals the antidiabetic property of vitamin D3 that is suggested to have therapeutic role through regulating glutamatergic function in diabetic rats.
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Affiliation(s)
- Sadanandan Jayanarayanan
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India
| | - Thoppil R Anju
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India
| | - Soman Smijin
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India
| | - Cheramadathikudiyil Skaria Paulose
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India.
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10
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Kyriazis GA, Smith KR, Tyrberg B, Hussain T, Pratley RE. Sweet taste receptors regulate basal insulin secretion and contribute to compensatory insulin hypersecretion during the development of diabetes in male mice. Endocrinology 2014; 155:2112-21. [PMID: 24712876 PMCID: PMC4020927 DOI: 10.1210/en.2013-2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
β-Cells rapidly secrete insulin in response to acute increases in plasma glucose but, upon further continuous exposure to glucose, insulin secretion progressively decreases. Although the mechanisms are unclear, this mode of regulation suggests the presence of a time-dependent glucosensory system that temporarily attenuates insulin secretion. Interestingly, early-stage β-cell dysfunction is often characterized by basal (ie, fasting) insulin hypersecretion, suggesting a disruption of these related mechanisms. Because sweet taste receptors (STRs) on β-cells are implicated in the regulation of insulin secretion and glucose is a bona fide STR ligand, we tested whether STRs mediate this sensory mechanism and participate in the regulation of basal insulin secretion. We used mice lacking STR signaling (T1R2(-/-) knockout) and pharmacologic inhibition of STRs in human islets. Mouse and human islets deprived of STR signaling hypersecrete insulin at short-term fasting glucose concentrations. Accordingly, 5-hour fasted T1R2(-/-) mice have increased plasma insulin and lower glucose. Exposure of isolated wild-type islets to elevated glucose levels reduced STR expression, whereas islets from diabetic (db/db) or diet-induced obese mouse models show similar down-regulation. This transcriptional reprogramming in response to hyperglycemia correlates with reduced STR function in these mouse models, leading to insulin hypersecretion. These findings reveal a novel mechanism by which insulin secretion is physiologically regulated by STRs and also suggest that, during the development of diabetes, STR function is compromised by hyperglycemia leading to hyperinsulinemia. These observations further suggest that STRs might be a promising therapeutic target to prevent and treat type 2 diabetes.
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Affiliation(s)
- George A Kyriazis
- Diabetes and Obesity Research Center (G.A.K., K.R.S., B.T., T.H., R.E.P.) Sanford-Burnham Medical Research Institute, Orlando, Florida 32827; Translational Research Institute for Metabolism and Diabetes (G.A.K., R.E.P.), Florida Hospital, Orlando, Florida 32804; and Translational Science (B.T.), Cardiovascular and Metabolic Disease, Mölndal, AstraZeneca, Sweden
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11
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Madec AM, Cassel R, Dubois S, Ducreux S, Vial G, Chauvin MA, Mesnier A, Chikh K, Bosco D, Rieusset J, Van Coppenolle F, Thivolet C. Losartan, an angiotensin II type 1 receptor blocker, protects human islets from glucotoxicity through the phospholipase C pathway. FASEB J 2013; 27:5122-30. [PMID: 24008754 DOI: 10.1096/fj.13-234104] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
As shown in a large clinical prospective trial, inhibition of the renin-angiotensin system (RAS) can delay the onset of type 2 diabetes in high-risk individuals. We evaluated the beneficial effects of RAS inhibition on β-cell function under glucotoxic conditions. Human islets from 13 donors were cultured in 5.5 mM (controls) or 16.7 mM glucose [high glucose (HG)] for 4 d with or without losartan (5 μM), a selective AT1R blocker, and/or U73122 (2 μM), a selective PLC inhibitor, during the last 2 d. HG induced RAS activation with overexpression of AT1R (P<0.05) and angiotensinogen (P<0.001) mRNAs. HG increased endoplasmic reticulum (ER) stress markers (P<0.001) such as GRP78, sXBP1, and ATF4 mRNAs and Grp78 protein levels (P<0.01). HG also decreased reticular calcium concentration (P<0.0001) and modified protein expressions of ER calcium pumps with reduction of SERCA2b (P<0.01) and increase of IP3R2 (P<0.05). Losartan prevented these deleterious effects and was associated with improved insulin secretion despite HG exposure. AT1R activation triggers the PLC-IP3-calcium pathway. Losartan prevented the increase of PLC β1 and γ1 protein levels induced by HG (P<0.05). U73122 reproduced all the protective effects of losartan. AT1R blockade protects human islets from the deleterious effects of glucose through inhibition of the PLC-IP3-calcium pathway.
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Affiliation(s)
- Anne-Marie Madec
- 2INSERM U1060/University Lyon 1/Inra 1235, Lyon-Sud Medicine, Faculty, 165 Chemin du Grand Revoyet-BP 12, 69921 Oullins Cedex, France.
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Beaudry JL, D'souza AM, Teich T, Tsushima R, Riddell MC. Exogenous glucocorticoids and a high-fat diet cause severe hyperglycemia and hyperinsulinemia and limit islet glucose responsiveness in young male Sprague-Dawley rats. Endocrinology 2013; 154:3197-208. [PMID: 23766132 DOI: 10.1210/en.2012-2114] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Corticosterone (CORT) and other glucocorticoids cause peripheral insulin resistance and compensatory increases in β-cell mass. A prolonged high-fat diet (HFD) induces insulin resistance and impairs β-cell insulin secretion. This study examined islet adaptive capacity in rats treated with CORT and a HFD. Male Sprague-Dawley rats (age ∼6 weeks) were given exogenous CORT (400 mg/rat) or wax (placebo) implants and placed on a HFD (60% calories from fat) or standard diet (SD) for 2 weeks (N = 10 per group). CORT-HFD rats developed fasting hyperglycemia (>11 mM) and hyperinsulinemia (∼5-fold higher than controls) and were 15-fold more insulin resistant than placebo-SD rats by the end of ∼2 weeks (Homeostatic Model Assessment for Insulin Resistance [HOMA-IR] levels, 15.08 ± 1.64 vs 1.0 ± 0.12, P < .05). Pancreatic β-cell function, as measured by HOMA-β, was lower in the CORT-HFD group as compared to the CORT-SD group (1.64 ± 0.22 vs 3.72 ± 0.64, P < .001) as well as acute insulin response (0.25 ± 0.22 vs 1.68 ± 0.41, P < .05). Moreover, β- and α-cell mass were 2.6- and 1.6-fold higher, respectively, in CORT-HFD animals compared to controls (both P < .05). CORT treatment increased p-protein kinase C-α content in SD but not HFD-fed rats, suggesting that a HFD may lower insulin secretory capacity via impaired glucose sensing. Isolated islets from CORT-HFD animals secreted more insulin in both low and high glucose conditions; however, total insulin content was relatively depleted after glucose challenge. Thus, CORT and HFD, synergistically not independently, act to promote severe insulin resistance, which overwhelms islet adaptive capacity, thereby resulting in overt hyperglycemia.
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Affiliation(s)
- Jacqueline L Beaudry
- School of Kinesiology and Health Science, Faculty of Health, Muscle Health Research Center and Physical Activity and Chronic Disease Unit, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3
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Jiménez-González M, Jaques F, Rodríguez S, Porciuncula A, Principe RM, Abizanda G, Iñiguez M, Escalada J, Salvador J, Prósper F, Halban PA, Barajas M. Cardiotrophin 1 protects beta cells from apoptosis and prevents streptozotocin-induced diabetes in a mouse model. Diabetologia 2013; 56:838-46. [PMID: 23358882 DOI: 10.1007/s00125-012-2822-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 12/05/2012] [Indexed: 11/29/2022]
Abstract
AIMS/HYPOTHESIS Cardiotrophin 1 (CT-1) is a recently described cytokine originally isolated from the heart where it has been shown to play an important role in apoptotic protection of cardiomyocytes and heart hypertrophy. Its beneficial properties have also been described in other organs such as liver and neuromuscular tissue. In the present study, we investigated whether CT-1 can confer protection against pro-apoptotic stimuli in pancreatic beta cells, and its role in insulin secretion and diabetes development. METHODS The effects of CT-1 on apoptosis and function were studied using MIN6B1 cells and freshly isolated murine pancreatic islets. The impact on the development of diabetes was evaluated in Ct1-null (Ct1 (-/-)) mice (the gene Ct1 is also known as Ctf1) using two streptozotocin (STZ)-induced models of diabetes. RESULTS CT-1 has a protective effect in MIN6B1 cells and murine islets under the pro-apoptotic stimulus of serum deprivation, which correlates with the expression of B cell lymphoma-extra large, or following exposure to a mixture of cytokines. In addition, CT-1 enhances glucose-stimulated insulin secretion in MIN6B1 cells and this was repressed by inhibitors of phospholipase C. Furthermore, Ct1 (-/-) mice were more prone to develop diabetes, and their glucose tolerance test showed impaired plasma glucose clearance which correlated with decreased pancreatic insulin secretion. CONCLUSIONS/INTERPRETATION The results obtained from both in vitro and in vivo experiments show that CT-1 improves beta cell function and survival, and protects mice against STZ-induced diabetes.
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Affiliation(s)
- M Jiménez-González
- Division of Oncology, Foundation for Applied Medical Research, University of Navarra, Pamplona, Spain
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Barker CJ, Berggren PO. New Horizons in Cellular Regulation by Inositol Polyphosphates: Insights from the Pancreaticβ-Cell. Pharmacol Rev 2013; 65:641-69. [DOI: 10.1124/pr.112.006775] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Barker CJ, Berggren PO. The pancreatic beta cell as a paradigm for advances in inositide research. Adv Biol Regul 2012; 52:361-368. [PMID: 22884029 DOI: 10.1016/j.jbior.2012.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 05/16/2012] [Indexed: 06/01/2023]
Abstract
In a previous review for Advances in Enzyme Research (Berggren and Barker, 2008) we outlined the history of our involvement in discovering important roles for inositides in the insulin secreting pancreatic beta cell. In this current appraisal we bring the work up to date and project how we believe this field will continue to develop in the future. Recently, we have seen an important synergism between the growth in our understanding of inositide function and our knowledge of beta cell stimulus-secretion coupling in both physiological and pathophysiological contexts. Important advances have been made in three areas. 1. The classic regulation of cytoplasmic free Ca(2+) concentration [Ca(2+)](i) by Inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) and its receptor, 2. A novel role of the inositol pyrophosphates, especially 5-diphosphoinositol pentakisphosphate (5-PP-InsP(5)), in exocytosis, and 3. The unique signaling roles of PI3K pathways instituted by the engagement of the insulin receptor in an autocrine, positive feed-back loop. We examine each of these in turn and close with an assessment of the likely future directions the research will take.
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Affiliation(s)
- Christopher J Barker
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
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Tomas NM, Masur K, Piecha JC, Niggemann B, Zänker KS. Akt and phospholipase Cγ are involved in the regulation of growth and migration of MDA-MB-468 breast cancer and SW480 colon cancer cells when cultured with diabetogenic levels of glucose and insulin. BMC Res Notes 2012; 5:214. [PMID: 22554284 PMCID: PMC3393613 DOI: 10.1186/1756-0500-5-214] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 05/03/2012] [Indexed: 12/11/2022] Open
Abstract
Background Epidemiological studies revealed a strong correlation between the metabolic syndrome/diabetes mellitus type 2 (DM2) and higher incidence and faster progression of breast and colon cancer. However, the underlying molecular mechanisms are widely unknown. Akt and phospholipase Cγ (PLCγ) are involved in tyrosine kinase signaling and promote tumor cell growth and migration. Therefore, we examined regulatory functions and expression of Akt and PLCγ in a simplified in vitro diabetogenic model. Findings Protein expression was determined by western blot analysis in MDA-MB-468 breast cancer and SW480 colon cancer cells previously cultured under physiologic (5.5 mM) and diabetogenic (11 mM) glucose concentrations (without and with 100 ng/ml insulin). We studied the culture effects on proliferation and migration of these cells, especially after inhibiting Akt and PLCγ. We found that Akt expression was up-regulated with high glucose and insulin in both cell lines, whereas PLCγ expression was enhanced in colon cancer cells only. High levels of glucose and insulin increased cell proliferation and migration in both cell lines in vitro, mediated by Akt and PLCγ, as shown through the specific pharmacological inhibitors A6730 and U73122. Conclusions Our molecular data explain glucose- and insulin-induced changes in a cancer cell and help to understand what might trigger tumor cell proliferation and migration in DM2 patients, too.
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Affiliation(s)
- Nicola M Tomas
- Institute of Immunology and Experimental Oncology, Witten/Herdecke University, Stockumer Str, 10, D-58448, Witten, Germany.
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Chan CB, Ye K. Phosphoinositide 3-kinase enhancer (PIKE) in the brain: is it simply a phosphoinositide 3-kinase/Akt enhancer? Rev Neurosci 2012; 23:153-61. [PMID: 22499674 DOI: 10.1515/revneuro-2011-0066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 12/12/2011] [Indexed: 02/06/2023]
Abstract
Since its discovery in 2000, phosphoinositide 3-kinase enhancer (PIKE) has been recognized as a class of GTPase that controls the enzymatic activities of phosphoinositide 3-kinase (PI3K) and Akt in the central nervous system (CNS). However, recent studies suggest that PIKEs are not only enhancers to PI3K/Akt but also modulators to other kinases including insulin receptor tyrosine kinase and focal adhesion kinases. Moreover, they regulate transcription factors such as signal transducer and activator of transcription and nuclear factor κB. Indeed, PIKE proteins participate in multiple cellular processes including control of cell survival, brain development, memory formation, gene transcription, and metabolism. In this review, we have summarized the functions of PIKE proteins in CNS and discussed their potential implications in various neurological disorders.
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Affiliation(s)
- Chi Bun Chan
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA.
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Fiume R, Ramazzotti G, Faenza I, Piazzi M, Bavelloni A, Billi AM, Cocco L. Nuclear PLCs affect insulin secretion by targeting PPARγ in pancreatic β cells. FASEB J 2011; 26:203-10. [PMID: 21974932 DOI: 10.1096/fj.11-186510] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Type 2 diabetes is a heterogeneous disorder caused by concomitant impairment of insulin secretion by pancreatic β cells and of insulin action in peripheral target tissues. Studies with inhibitors and agonists established a role for PLC in the regulation of insulin secretion but did not distinguish between effects due to nuclear or cytoplasmic PLC signaling pathways that act in a distinct fashion. We report that in MIN6 β cells, PLCβ1 localized in both nucleus and cytoplasm, PLCδ4 in the nucleus, and PLCγ1 in the cytoplasm. By silencing each isoform, we observed that they all affected glucose-induced insulin release both at basal and high glucose concentrations. To elucidate the molecular basis of PLC regulation, we focused on peroxisome proliferator-activated receptor-γ (PPARγ), a nuclear receptor transcription factor that regulates genes critical to β-cell maintenance and functions. Silencing of PLCβ1 and PLCδ4 resulted in a decrease in the PPARγ mRNA level. By means of a PPARγ-promoter-luciferase assay, the decrease could be attributed to a PLC action on the PPARγ-promoter region. The effect was specifically observed on silencing of the nuclear and not the cytoplasmic PLC. These findings highlight a novel pathway by which nuclear PLCs affect insulin secretion and identify PPARγ as a novel molecular target of nuclear PLCs.
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Affiliation(s)
- Roberta Fiume
- Department of Human Anatomy, University of Bologna, Bologna, Italy
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Bimboese P, Gibson CJ, Schmidt S, Xiang W, Ehrlich BE. Isoform-specific regulation of the inositol 1,4,5-trisphosphate receptor by O-linked glycosylation. J Biol Chem 2011; 286:15688-97. [PMID: 21383013 DOI: 10.1074/jbc.m110.206482] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The inositol 1,4,5-trisphosphate receptor (InsP(3)R), an intracellular calcium channel, has three isoforms with >65% sequence homology, yet the isoforms differ in their function and regulation by post-translational modifications. We showed previously that InsP(3)R-1 is functionally modified by O-linked β-N-acetylglucosamine glycosylation (O-GlcNAcylation) (Rengifo, J., Gibson, C. J., Winkler, E., Collin, T., and Ehrlich, B. E. (2007) J. Neurosci. 27, 13813-13821). We now report the effect of O-GlcNAcylation on InsP(3)R-2 and InsP(3)R-3. Analysis of AR4-2J cells, a rat pancreatoma cell line expressing predominantly InsP(3)R-2, showed no detectable O-GlcNAcylation of InsP(3)R-2 and no significant functional changes despite the presence of the enzymes for addition (O-β-N-acetylglucosaminyltransferase) and removal (O-β-N-acetylglucosaminidase) of the monosaccharide. In contrast, InsP(3)R-3 in Mz-ChA-1 cells, a human cholangiocarcinoma cell line expressing predominantly InsP(3)R-3, was functionally modified by O-GlcNAcylation. Interestingly, the functional impact of O-GlcNAcylation on the InsP(3)R-3 channel was opposite the effect measured with InsP(3)R-1. Addition of O-GlcNAc by O-β-N-acetylglucosaminyltransferase increased InsP(3)R-3 single channel open probability. Incubation of Mz-ChA-1 cells in hyperglycemic medium caused an increase in the InsP(3)-dependent calcium release from the endoplasmic reticulum. The dynamic and inducible nature of O-GlcNAcylation and the InsP(3)R isoform specificity suggest that this form of modification of InsP(3)R and subsequent changes in intracellular calcium transients are important in physiological and pathophysiological processes.
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Affiliation(s)
- Patricia Bimboese
- Department of Pharmacology, Yale University, New Haven, Connecticut 06520-8066, USA
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