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Baghestani S, Haldin C, Kosijer P, Alam CM, Toivola DM. β-Cell keratin 8 maintains islet mechanical integrity, mitochondrial ultrastructure, and β-cell glucose transporter 2 plasma membrane targeting. Am J Physiol Cell Physiol 2024; 327:C462-C476. [PMID: 38912736 DOI: 10.1152/ajpcell.00123.2024] [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: 02/21/2024] [Revised: 05/31/2024] [Accepted: 06/12/2024] [Indexed: 06/25/2024]
Abstract
Islet β-cell dysfunction is an underlying factor for type I diabetes (T1D) development. Insulin sensing and secretion are tightly regulated in β-cells at multiple subcellular levels. The epithelial intermediate filament (IF) protein keratin (K) 8 is the main β-cell keratin, constituting the filament network with K18. To identify the cell-autonomous functions of K8 in β-cells, mice with targeted deletion of β-cell K8 (K8flox/flox; Ins-Cre) were analyzed for islet morphology, ultrastructure, and integrity, as well as blood glucose regulation and streptozotocin (STZ)-induced diabetes development. Glucose transporter 2 (GLUT2) localization was studied in β-cells in vivo and in MIN6 cells with intact or disrupted K8/K18 filaments. Loss of β-cell K8 leads to a major reduction in K18. Islets without β-cell K8 are more fragile, and these β-cells display disjointed plasma membrane organization with less membranous E-cadherin and smaller mitochondria with diffuse cristae. Lack of β-cell K8 also leads to a reduced glucose-stimulated insulin secretion (GSIS) response in vivo, despite undisturbed systemic blood glucose regulation. K8flox/flox, Ins-Cre mice have a decreased sensitivity to STZ compared with K8 wild-type mice, which is in line with decreased membranous GLUT2 expression observed in vivo, as GLUT2 is required for STZ uptake in β-cells. In vitro, MIN6 cell plasma membrane GLUT2 is rescued in cells overexpressing K8/K18 filaments but mistargeted in cells with disrupted K8/K18 filaments. β-Cell K8 is required for islet and β-cell structural integrity, normal mitochondrial morphology, and GLUT2 plasma membrane targeting, and has implications on STZ sensitivity as well as systemic insulin responses.NEW & NOTEWORTHY Keratin 8 is the main cytoskeletal protein in the cytoplasmic intermediate filament network in β-cells. Here for the first time, we assessed the β-cell autonomous mechanical and nonmechanical roles of keratin 8 in β-cell function. We demonstrated the importance of keratin 8 in islet and β-cell structural integrity, maintaining mitochondrial morphology and GLUT2 plasma membrane targeting.
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Affiliation(s)
- Sarah Baghestani
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship, Åbo Akademi University, Turku, Finland
| | - Caroline Haldin
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship, Åbo Akademi University, Turku, Finland
| | - Petar Kosijer
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship, Åbo Akademi University, Turku, Finland
| | - Catharina M Alam
- School of Applied Sciences, Edinburgh Napier University, Edinburg, United Kingdom
| | - Diana M Toivola
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship, Åbo Akademi University, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
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Siewe N, Friedman A. A mathematical model of obesity-induced type 2 diabetes and efficacy of anti-diabetic weight reducing drug. J Theor Biol 2024; 581:111756. [PMID: 38307451 DOI: 10.1016/j.jtbi.2024.111756] [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: 08/17/2023] [Revised: 11/04/2023] [Accepted: 01/26/2024] [Indexed: 02/04/2024]
Abstract
The dominant paradigm for modeling the obesity-induced T2DM (type 2 diabetes mellitus) today focuses on glucose and insulin regulatory systems, diabetes pathways, and diagnostic test evaluations. The problem with this approach is that it is not possible to explicitly account for the glucose transport mechanism from the blood to the liver, where the glucose is stored, and from the liver to the blood. This makes it inaccurate, if not incorrect, to properly model the concentration of glucose in the blood in comparison to actual glycated hemoglobin (A1C) test results. In this paper, we develop a mathematical model of glucose dynamics by a system of ODEs. The model includes the mechanism of glucose transport from the blood to the liver, and from the liver to the blood, and explains how obesity is likely to lead to T2DM. We use the model to evaluate the efficacy of an anti-T2DM drug that also reduces weight.
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Affiliation(s)
- Nourridine Siewe
- School of Mathematics and Statistics, College of Science, Rochester Institute of Technology, Rochester, NY, USA.
| | - Avner Friedman
- Department of Mathematics, The Ohio State University, Columbus, OH, USA
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Morrice N, Vainio S, Mikkola K, van Aalten L, Gallagher JR, Ashford MLJ, McNeilly AD, McCrimmon RJ, Grosfeld A, Serradas P, Koffert J, Pearson ER, Nuutila P, Sutherland C. Metformin increases the uptake of glucose into the gut from the circulation in high-fat diet-fed male mice, which is enhanced by a reduction in whole-body Slc2a2 expression. Mol Metab 2023; 77:101807. [PMID: 37717665 PMCID: PMC10550722 DOI: 10.1016/j.molmet.2023.101807] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/28/2023] [Accepted: 09/12/2023] [Indexed: 09/19/2023] Open
Abstract
OBJECTIVES Metformin is the first line therapy recommended for type 2 diabetes. However, the precise mechanism of action remains unclear and up to a quarter of patients show some degree of intolerance to the drug, with a similar number showing poor response to treatment, limiting its effectiveness. A better understanding of the mechanism of action of metformin may improve its clinical use. SLC2A2 (GLUT2) is a transmembrane facilitated glucose transporter, with important roles in the liver, gut and pancreas. Our group previously identified single nucleotide polymorphisms in the human SLC2A2 gene, which were associated with reduced transporter expression and an improved response to metformin treatment. The aims of this study were to model Slc2a2 deficiency and measure the impact on glucose homoeostasis and metformin response in mice. METHODS We performed extensive metabolic phenotyping and 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG)-positron emission tomography (PET) analysis of gut glucose uptake in high-fat diet-fed (HFD) mice with whole-body reduced Slc2a2 (Slc2a2+/-) and intestinal Slc2a2 KO, to assess the impact of metformin treatment. RESULTS Slc2a2 partial deficiency had no major impact on body weight and insulin sensitivity, however mice with whole-body reduced Slc2a2 expression (Slc2a2+/-) developed an age-related decline in glucose homoeostasis (as measured by glucose tolerance test) compared to wild-type (Slc2a2+/+) littermates. Glucose uptake into the gut from the circulation was enhanced by metformin exposure in Slc2a2+/+ animals fed HFD and this action of the drug was significantly higher in Slc2a2+/- animals. However, there was no effect of specifically knocking-out Slc2a2 in the mouse intestinal epithelial cells. CONCLUSIONS Overall, this work identifies a differential metformin response, dependent on expression of the SLC2A2 glucose transporter, and also adds to the growing evidence that metformin efficacy includes modifying glucose transport in the gut. We also describe a novel and important role for this transporter in maintaining efficient glucose homoeostasis during ageing.
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Affiliation(s)
- Nicola Morrice
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Susanne Vainio
- Turku PET Centre, University of Turku, Turku, Finland; MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Kirsi Mikkola
- Turku PET Centre, University of Turku, Turku, Finland; MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Lidy van Aalten
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Jennifer R Gallagher
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Michael L J Ashford
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Alison D McNeilly
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Rory J McCrimmon
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Alexandra Grosfeld
- Sorbonne Université, Inserm, Centre de Recherche Saint-Antoine, CRSA, F-75012, Paris, France
| | - Patricia Serradas
- Sorbonne Université, INSERM, Nutrition and Obesities: Systemic approaches, NutriOmics, Research group, F-75013, Paris, France
| | - Jukka Koffert
- Turku PET Centre, University of Turku, Turku, Finland; Department of Gastroenterology, Turku University Hospital, Turku, Finland
| | - Ewan R Pearson
- Division of Population Health and Genomics, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland; Department of Endocrinology, Turku University Hospital, Turku, Finland
| | - Calum Sutherland
- Division of Cellular and Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, DD1 9SY, UK.
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Bourebaba L, Serwotka-Suszczak A, Bourebaba N, Zyzak M, Marycz K. The PTP1B Inhibitor Trodusquemine (MSI-1436) Improves Glucose Uptake in Equine Metabolic Syndrome Affected Liver through Anti-Inflammatory and Antifibrotic Activity. Int J Inflam 2023; 2023:3803056. [PMID: 37808009 PMCID: PMC10560121 DOI: 10.1155/2023/3803056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 08/12/2023] [Accepted: 09/08/2023] [Indexed: 10/10/2023] Open
Abstract
Background Hyperactivation of protein tyrosine phosphatase (PTP1B) has been associated with several metabolic malfunctions ranging from insulin resistance, metaflammation, lipotoxicity, and hyperglycaemia. Liver metabolism failure has been proposed as a core element in underlying endocrine disorders through persistent inflammation and highly fibrotic phenotype. Methods In this study, the outcomes of PTP1B inhibition using trodusquemine (MSI-1436) on key equine metabolic syndrome (EMS)-related alterations including inflammation, fibrosis, and glucose uptake have been analyzed in liver explants collected from EMS-affected horses using various analytical techniques, namely, flow cytometry, RT-qPCR, and Western blot. Results PTP1B inhibition using trodusquemine resulted in decreased proinflammatory cytokines (IL-1β, TNF-α, and IL-6) release from liver and PBMC affected by EMS and regulated expression of major proinflammatory microRNAs such as miR-802 and miR-211. Moreover, MSI-1436 enhanced the anti-inflammatory profile of livers by elevating the expression of IL-10 and IL-4 and activating CD4+CD25+Foxp3+ regulatory T cells in treated PBMC. Similarly, the inhibitor attenuated fibrogenic pathways in the liver by downregulating TGF-β/NOX1/4 axis and associated MMP-2/9 overactivation. Interestingly, PTP1B inhibition ameliorated the expression of TIMP-1 and Smad7, both important antifibrotic mediators. Furthermore, application of MSI-1436 was found to augment the abundance of glycosylated Glut-2, which subsequently expanded the glucose absorption in the EMS liver, probably due to an enhanced Glut-2 stability and half-life onto the plasma cell membranes. Conclusion Taken together, the presented data suggest that the PTP1B inhibition strategy and the use of its specific inhibitor MSI-1436 represents a promising option for the improvement of liver tissue integrity and homeostasis in the course of EMS and adds more insights for ongoing clinical trials for human MetS management.
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Affiliation(s)
- Lynda Bourebaba
- Department of Experimental Biology, Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Norwida 27B, Wrocław 50-375, Poland
| | - Anna Serwotka-Suszczak
- Department of Experimental Biology, Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Norwida 27B, Wrocław 50-375, Poland
| | - Nabila Bourebaba
- Department of Experimental Biology, Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Norwida 27B, Wrocław 50-375, Poland
| | - Magdalena Zyzak
- Department of Experimental Biology, Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Norwida 27B, Wrocław 50-375, Poland
| | - Krzysztof Marycz
- Department of Experimental Biology, Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Norwida 27B, Wrocław 50-375, Poland
- Department of Veterinary Medicine and Epidemiology, Veterinary Institute for Regenerative Cures, School of Veterinary Medicine, University of California, Davis, CA 95516, USA
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Saji N, Francis N, Schwarz LJ, Blanchard CL, Santhakumar AB. Rice Bran Phenolic Extracts Modulate Insulin Secretion and Gene Expression Associated with β-Cell Function. Nutrients 2020; 12:nu12061889. [PMID: 32599958 PMCID: PMC7353197 DOI: 10.3390/nu12061889] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/14/2020] [Accepted: 06/20/2020] [Indexed: 12/21/2022] Open
Abstract
Oxidative stress is known to modulate insulin secretion and initiate gene alterations resulting in impairment of β-cell function and type 2 diabetes mellitus (T2DM). Rice bran (RB) phenolic extracts contain bioactive properties that may target metabolic pathways associated with the pathogenesis of T2DM. This study aimed to examine the effect of stabilized RB phenolic extracts on the expression of genes associated with β-cell function such as glucose transporter 2 (Glut2), pancreatic and duodenal homeobox 1 (Pdx1), sirtuin 1 (Sirt1), mitochondrial transcription factor A (Tfam), and insulin 1 (Ins1) in addition to evaluating its impact on glucose-stimulated insulin secretion. It was observed that treatment with different concentrations of RB phenolic extracts (25-250 µg/mL) significantly increased the expression of Glut2, Pdx1, Sirt1, Tfam, and Ins1 genes and glucose-stimulated insulin secretion under both normal and high glucose conditions. RB phenolic extracts favourably modulated the expression of genes involved in β-cell dysfunction and insulin secretion via several mechanisms such as synergistic action of polyphenols targeting signalling molecules, decreasing free radical damage by its antioxidant activity, and stimulation of effectors or survival factors of insulin secretion.
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Affiliation(s)
- Nancy Saji
- Australian Research Council (ARC) Industrial Transformation Training Centre (ITTC) for Functional Grains, Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2650, Australia; (N.S.); (N.F.); (L.J.S.); (C.L.B.)
- School of Biomedical Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
| | - Nidhish Francis
- Australian Research Council (ARC) Industrial Transformation Training Centre (ITTC) for Functional Grains, Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2650, Australia; (N.S.); (N.F.); (L.J.S.); (C.L.B.)
- School of Animal and Veterinary Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
| | - Lachlan J. Schwarz
- Australian Research Council (ARC) Industrial Transformation Training Centre (ITTC) for Functional Grains, Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2650, Australia; (N.S.); (N.F.); (L.J.S.); (C.L.B.)
- School of Agricultural and Wine Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
| | - Christopher L. Blanchard
- Australian Research Council (ARC) Industrial Transformation Training Centre (ITTC) for Functional Grains, Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2650, Australia; (N.S.); (N.F.); (L.J.S.); (C.L.B.)
- School of Biomedical Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
| | - Abishek B. Santhakumar
- Australian Research Council (ARC) Industrial Transformation Training Centre (ITTC) for Functional Grains, Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2650, Australia; (N.S.); (N.F.); (L.J.S.); (C.L.B.)
- School of Biomedical Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
- Correspondence: ; Tel.: +61-2-6933-2678
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1-Palmitoyl-2-Linoleoyl-3-Acetyl- rac-Glycerol Attenuates Streptozotocin-Induced Pancreatic Beta Cell Damage by Promoting Glucose Transporter 2 Endocytosis. Mol Cell Biol 2019; 39:MCB.00157-19. [PMID: 31481450 PMCID: PMC6791655 DOI: 10.1128/mcb.00157-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/14/2019] [Indexed: 01/09/2023] Open
Abstract
Streptozotocin (STZ) is widely used to induce diabetic rodent models. It is specifically toxic to pancreatic beta cells and causes severe destruction and dysfunction. We investigated the effect of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) on an STZ-induced diabetic mouse model. PLAG attenuated the glucose increase and maintained serum insulin at levels similar to those seen with control mice. Streptozotocin (STZ) is widely used to induce diabetic rodent models. It is specifically toxic to pancreatic beta cells and causes severe destruction and dysfunction. We investigated the effect of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) on an STZ-induced diabetic mouse model. PLAG attenuated the glucose increase and maintained serum insulin at levels similar to those seen with control mice. In pancreatic beta cell line INS-1, STZ-induced cell apoptosis and intracellular reactive oxygen species (ROS) generation were significantly reduced to nearly normal levels after PLAG treatment. Glucose transporter 2 (GLUT2) localization analyses and glucose uptake assays showed that PLAG accelerated GLUT2 internalization, which ameliorated excessive entry of glucose, as well as STZ. STZ-induced cytotoxic effects were significantly reduced in PLAG-treated groups. The biological activity of PLAG was further confirmed in GLUT2-silenced cells, and the specificity of PLAG was verified using its derivative 1-palmitoyl-2-linoleoyl-3-hydroxyl-rac-glycerol (PLH). Our results suggest that PLAG may be a useful agent for protecting beta cells in the setting of excessive glucose influx.
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Đorđević M, Grdović N, Mihailović M, Arambašić Jovanović J, Uskoković A, Rajić J, Sinadinović M, Tolić A, Mišić D, Šiler B, Poznanović G, Vidaković M, Dinić S. Centaurium erythraea extract improves survival and functionality of pancreatic beta-cells in diabetes through multiple routes of action. JOURNAL OF ETHNOPHARMACOLOGY 2019; 242:112043. [PMID: 31252092 DOI: 10.1016/j.jep.2019.112043] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 06/09/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Centaurium erythraea Rafn (CE) is used as a traditional medicinal plant in Serbia to treat different ailments due to its antidiabetic, antipyretic, antiflatulent and detoxification effects. AIM OF THE STUDY Elucidation of the mechanisms that underlie the antioxidant and pro-survival effects of the CE extract (CEE) in beta-cells and pancreatic islets from streptozotocin (STZ)-treated diabetic rats. MATERIAL AND METHODS Diabetes was induced in rats by multiple applications of low doses of STZ (40 mg/kg intraperitoneally (i.p.), for five consecutive days). CEE (100 mg/kg) was administered orally, in the pre-treated group for two weeks before diabetes induction, during the treatments with STZ and for four weeks after diabetes onset, and in the post-treatment group for four weeks after diabetes induction. The impact of CEE on diabetic islets was estimated by histological and immunohistochemical examination of the pancreas. Molecular mechanisms of the effects of CEE were also analyzed in insulinoma Rin-5F cells treated with STZ (12 mM) and CEE (0.25 mg/mL). Oxidative stress was evaluated by assessing the levels of DNA damage, lipid peroxidation, protein S-glutathionylation and enzymatic activities and expression of CAT, MnSOD, CuZnSOD, GPx and GR in beta-cells. The presence and activities of the redox-sensitive and islet-enriched regulatory proteins were also analyzed. RESULTS Treatment with CEE ameliorated the insulin level and glycemic control in STZ-induced diabetic rats by improving the structural and functional properties of pancreatic islets through multiple routes of action. The disturbance of islet morphology and islet cell contents in diabetes was reduced by the CEE treatment and was associated with a protective effect of CEE on the levels of insulin, GLUT-2 and p-Akt in diabetic islets. The antioxidant effect of CEE on STZ-treated beta-cells was displayed as reduced DNA damage, lipid peroxidation, protein S-glutathionylation and alleviation of STZ-induced disruption in MnSOD, CuZnSOD and CAT enzyme activities. The oxidative stress-induced disturbance of the transcriptional regulation of CAT, MnSOD, CuZnSOD, GPx and GR enzymes in beta-cells was improved after the CEE treatment, and was observed as readjustment of the presence and activities of redox-sensitive NFκB-p65, FOXO3A, Sp1 and Nrf-2 transcription factors. The observed CEE-mediated induction of proliferative and pro-survival pathways and insulin expression/secretion after STZ-induced oxidative stress in beta-cells could be partially attributed to a fine-tuned modulation of the activities of pro-survival Akt, ERK and p38 kinases and islet-enriched Pdx-1 and MafA regulatory factors. CONCLUSIONS The results of this study provide evidence that CEE improves the structural and functional properties of pancreatic beta-cells by correcting the endogenous antioxidant regulatory mechanisms and by promoting proliferative and pro-survival pathways in beta-cells.
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Affiliation(s)
- Miloš Đorđević
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Nevena Grdović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Mirjana Mihailović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Jelena Arambašić Jovanović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Aleksandra Uskoković
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Jovana Rajić
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Marija Sinadinović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Anja Tolić
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Danijela Mišić
- Department of Plant Physiology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Branislav Šiler
- Department of Plant Physiology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Goran Poznanović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Melita Vidaković
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Svetlana Dinić
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
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Schmidt L, Wielsch N, Wang D, Boland W, Burse A. Tissue-specific profiling of membrane proteins in the salicin sequestering juveniles of the herbivorous leaf beetle, Chrysomela populi. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 109:81-91. [PMID: 30922827 DOI: 10.1016/j.ibmb.2019.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/21/2019] [Accepted: 03/21/2019] [Indexed: 06/09/2023]
Abstract
Sequestration of plant secondary metabolites is a detoxification strategy widespread in herbivorous insects including not only storage, but also usage of these metabolites for the insects' own benefit. Larvae of the poplar leaf beetle Chrysomela populi sequester plant-derived salicin to produce the deterrent salicylaldehyde in specialized exocrine glands. To identify putative transporters involved in the sequestration process we investigated integral membrane proteins of several tissues from juvenile C. populi by using a proteomics approach. Computational analyses led to the identification of 122 transport proteins in the gut, 105 in the Malpighian tubules, 94 in the fat body and 27 in the defensive glands. Among these, primary active transporters as well as electrochemical potential-driven transporters were most abundant in all tissues, including ABC transporters (especially subfamilies B, C and G) and sugar porters as most interesting families facilitating the sequestration of plant glycosides. Whereas ABC transporters are predominantly expressed simultaneously in several tissues, sugar porters are often expressed in only one tissue, suggesting that sugar porters govern more distinct functions than members of the ABC family. The inventory of transporters presented in this study provides the base for further functional characterizations on transport processes of sequestered glycosides in insects.
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Affiliation(s)
- Lydia Schmidt
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Natalie Wielsch
- Max Planck Institute for Chemical Ecology, Research Group Mass Spectrometry/ Proteomics, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Ding Wang
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Wilhelm Boland
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Antje Burse
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany.
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Ding L, Han L, Dube J, Billadeau DD. WASH Regulates Glucose Homeostasis by Facilitating Glut2 Receptor Recycling in Pancreatic β-Cells. Diabetes 2019; 68:377-386. [PMID: 30425062 DOI: 10.2337/db18-0189] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 10/31/2018] [Indexed: 11/13/2022]
Abstract
WASH is an endosomal protein belonging to the Wiskott-Aldrich syndrome protein superfamily that participates in endosomal receptor trafficking by facilitating tubule fission via activation of the ubiquitously expressed Arp2/3 complex. While several studies have begun to elucidate an understanding of the functions of WASH in cells lines, the in vivo function of WASH has not been fully elucidated, since total body deletion in mice leads to early embryonic lethality. To circumvent this problem, we have used a WASH conditional knockout mouse model to investigate the role of WASH in the pancreas. We find that pancreas-specific deletion of WASH leads to impaired blood glucose clearance and reduced insulin release upon glucose stimulation. Furthermore, WASH depletion results in impaired trafficking of Glut2 in pancreatic β-cells as a consequence of an intracellular accumulation of Glut2 and overall decreased levels of Glut2 protein. Taken together, these results indicate that WASH participates in pancreatic β-cell glucose sensing and whole-body glucose homeostasis. Thus, patients harboring mutations in components of the WASH complex could be at risk for developing type 2 diabetes.
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Affiliation(s)
- Li Ding
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN
| | - Lingling Han
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN
| | - John Dube
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN
| | - Daniel D Billadeau
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN
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10
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Ghezzi C, Calmettes G, Morand P, Ribalet B, John S. Real-time imaging of sodium glucose transporter (SGLT1) trafficking and activity in single cells. Physiol Rep 2018; 5:5/3/e13062. [PMID: 28193781 PMCID: PMC5309568 DOI: 10.14814/phy2.13062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 11/07/2016] [Indexed: 01/12/2023] Open
Abstract
The processes controlling targeting of glucose transporters to apical and basolateral membranes of polarized cells are complex and not-well understood. We have engineered SGLT1 and GLUT4 constructs linked to fluorescent proteins to highlight the differences in transporter expression and trafficking, in real time, in different cell types. Activity was assessed in parallel using a FRET glucose sensor. In COS cells and HEK cells, SGLT1 was distributed between the plasma membrane and intracellular compartments, but there was little expression in CHO cells. Trafficking was investigated using the lysosome inhibitors NH4Cl (10 mmol/L) and chloroquine (150 μmol/L) and the proteasome inhibitors MG-262 (1 μmol/L) and lactacystin (5 μmol/L). Lysosome inhibitors caused SGLT1 accumulation into intracellular bodies, whereas proteasome inhibitors induced SGLT1 accumulation in the plasma membrane, even in CHO cells. Our data suggest that a fraction of SGLT1 is rapidly degraded by lysosomes and never reached the plasma membrane; another fraction reaches the membrane and is subsequently degraded by lysosomes following internalization. The latter process is regulated by the ubiquitin/proteasome pathway, acting at a late stage of the lysosomal pathway. Using the cholesterol inhibitor MβCD (3 mmol/L), a dominant negative dynamin (K44A) and caveolin, we showed that SGLT1 internalization is lipid raft-mediated, but caveolin-independent. In contrast, GLUT4 internalization is dynamin-dependent, but cholesterol-independent. The physiological relevance of these data is discussed in terms of differential membrane compartmentalization of the transporters and expression under stress conditions.
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Affiliation(s)
- Chiara Ghezzi
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Guillaume Calmettes
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Pauline Morand
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Bernard Ribalet
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Scott John
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
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11
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Zafar M, Naydenova Z, Coe IR. Extended exposure to substrate regulates the human equilibrative nucleoside transporter 1 (hENT1). NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 35:631-642. [PMID: 27906634 DOI: 10.1080/15257770.2016.1200074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human equilibrative nucleoside transporter 1 (hENT1) is a major route of entry of nucleosides and nucleoside analog drugs. The regulation of hENT1 is poorly understood in spite of its clinical importance as a drug transporter. Immunofluorescence microscopy and fluorescence-activated cell sorting suggested that cytidine pre-treatment (40 μM, 6 h) promotes hENT1 internalization in a way that does not affect either hENT1-mediated nucleoside uptake or gemcitabine-induced cytotoxicity. The Scatchard plot analyses of our NBTI binding data support previous speculations that hENT1 proteins exist as two sub-populations, and suggest that cytidine pre-treatment leads to the internalization of one population.
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Affiliation(s)
- Maliha Zafar
- a Department of Chemistry and Biology , Ryerson University , Toronto , Canada
| | - Zlatina Naydenova
- a Department of Chemistry and Biology , Ryerson University , Toronto , Canada
| | - Imogen R Coe
- a Department of Chemistry and Biology , Ryerson University , Toronto , Canada
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12
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Neelankal John A, Morahan G, Jiang FX. Incomplete Re-Expression of Neuroendocrine Progenitor/Stem Cell Markers is a Key Feature of β-Cell Dedifferentiation. J Neuroendocrinol 2017; 29. [PMID: 27891681 DOI: 10.1111/jne.12450] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 01/23/2023]
Abstract
There is increasing evidence to suggest that type 2 diabetes mellitus (T2D), a pandemic metabolic disease, may be caused by β-cell dedifferentiation (βCD). However, there is currently no universal definition of βCD, and the underlying mechanism is poorly understood. We hypothesise that a high-glucose in vitro environment mimics hyperglycaemia in vivo and that β cells grown in this milieu over a long period will undergo dedifferentiation. In the present study, we report that the pancreatic β cell line mouse insulinoma 6 (MIN6) grown under a high-glucose condition did not undergo massive cell death but exhibited a glucose-stimulated insulin-secreting profile similar to that of immature β cells. The expression of insulin and the glucose-sensing molecule glucose transporter 2 (Glut2) in late passage MIN6 cells was significantly lower than the early passage at both the RNA and protein levels. Mechanistically, these cells also expressed significantly less of the 'pancreatic and duodenal homebox1' (Pdx1) β-cell transcription factor. Finally, passaged MIN6 cells dedifferentiated to demonstrate some features of β-cell precursors, as well as neuroendocrine markers, in addition to expressing both glucagon and insulin. Thus, we concluded that high-glucose passaged MIN6 cells passaged MIN6 cells. provide a cellular model of β-cell dedifferentiation that can help researchers develop a better understanding of this process. These findings provide new insights that may enhance knowledge of the pathophysiology of T2D and facilitate the establishment of a novel strategy by which this disease can be treated.
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Affiliation(s)
- A Neelankal John
- Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Australia
- School of Medicine And Pharmacology, University of Western Australia, Carwley, Australia
| | - G Morahan
- Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Australia
- School of Medicine And Pharmacology, University of Western Australia, Carwley, Australia
| | - F-X Jiang
- Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Australia
- School of Medicine And Pharmacology, University of Western Australia, Carwley, Australia
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13
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Alam K, Pahwa S, Wang X, Zhang P, Ding K, Abuznait AH, Li L, Yue W. Downregulation of Organic Anion Transporting Polypeptide (OATP) 1B1 Transport Function by Lysosomotropic Drug Chloroquine: Implication in OATP-Mediated Drug-Drug Interactions. Mol Pharm 2016; 13:839-51. [PMID: 26750564 PMCID: PMC4970216 DOI: 10.1021/acs.molpharmaceut.5b00763] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Organic anion transporting polypeptide (OATP) 1B1 mediates the hepatic uptake of many drugs including lipid-lowering statins. Decreased OATP1B1 transport activity is often associated with increased systemic exposure of statins and statin-induced myopathy. Antimalarial drug chloroquine (CQ) is also used for long-term treatment of rheumatoid arthritis and systemic lupus erythematosus. CQ is lysosomotropic and inhibits protein degradation in lysosomes. The current studies were designed to determine the effects of CQ on OATP1B1 protein degradation, OATP1B1-mediated transport in OATP1B1-overexpressing cell line, and statin uptake in human sandwich-cultured hepatocytes (SCH). Treatment with lysosome inhibitor CQ increased OATP1B1 total protein levels in HEK293-OATP1B1 cells and in human SCH as determined by OATP1B1 immunoblot. In HEK293-FLAG-tagged OATP1B1 stable cell line, co-immunofluorescence staining indicated that intracellular FLAG-OATP1B1 is colocalized with lysosomal associated membrane glycoprotein (LAMP)-2, a marker protein of late endosome/lysosome. Enlarged LAMP-2-positive vacuoles with FLAG-OATP1B1 protein retained inside were readily detected in CQ-treated cells, consistent with blocking lysosomal degradation of OATP1B1 by CQ. In HEK293-OATP1B1 cells, without pre-incubation, CQ concentrations up to 100 μM did not affect OATP1B1-mediated [(3)H]E217G accumulation. However, pre-incubation with CQ at clinically relevant concentration(s) significantly decreased [(3)H]E217G and [(3)H]pitavastatin accumulation in HEK293-OATP1B1 cells and [(3)H]pitavastatin accumulation in human SCH. CQ pretreatment (25 μM, 2 h) resulted in ∼1.9-fold decrease in Vmax without affecting Km of OATP1B1-mediated [(3)H]E217G transport in HEK293-OATP1B1 cells. Pretreatment with monensin and bafilomycin A1, which also have lysosome inhibition activity, significantly decreased OATP1B1-mediated transport in HEK293-OATP1B1 cells. Pharmacoepidemiologic studies using data from the U.S. Food and Drug Administration Adverse Event Reporting System indicated that CQ plus pitavastatin, rosuvastatin, and pravastatin, which are minimally metabolized by the cytochrome P450 enzymes, led to higher myopathy risk than these statins alone. In summary, the present studies report novel findings that lysosome is involved in degradation of OATP1B1 protein and that pre-incubation with lysosomotropic drug CQ downregulates OATP1B1 transport activity. Our in vitro data in combination with pharmacoepidemiologic studies support that CQ has potential to cause OATP-mediated drug-drug interactions.
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Affiliation(s)
- Khondoker Alam
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73117, United States
| | - Sonia Pahwa
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73117, United States
| | - Xueying Wang
- Center for Computational Biology and Bioinformatics, Indiana Institute of Personalized Medicine, Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202, United States
| | - Pengyue Zhang
- Center for Computational Biology and Bioinformatics, Indiana Institute of Personalized Medicine, Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202, United States
| | - Kai Ding
- Department of Biostatistics and Epidemiology, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73126, United States
| | - Alaa H. Abuznait
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73117, United States
| | - Lang Li
- Center for Computational Biology and Bioinformatics, Indiana Institute of Personalized Medicine, Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202, United States
| | - Wei Yue
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73117, United States
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14
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Adam SH, Giribabu N, Rao PV, Sayem ASM, Arya A, Panichayupakaranant P, Korla PK, Salleh N. Rhinacanthin C ameliorates hyperglycaemia, hyperlipidemia and pancreatic destruction in streptozotocin–nicotinamide induced adult male diabetic rats. Eur J Pharmacol 2016; 771:173-90. [PMID: 26703866 DOI: 10.1016/j.ejphar.2015.12.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/11/2015] [Accepted: 12/14/2015] [Indexed: 02/05/2023]
Affiliation(s)
- Siti Hajar Adam
- Department of Physiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Nelli Giribabu
- Department of Physiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Pasupuleti Visweswara Rao
- Faculty of Agro Based Industry, University Malaysia Kelantan, Campus Jeli, Locked Bag No. 100, 17600 Jeli, Kelantan, Malaysia
| | - Abu Sadat Md Sayem
- Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Aditya Arya
- Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Pharkphoom Panichayupakaranant
- Department of Pharmacognosy and Pharmaceutical Botany & Phytomedicine and Pharmaceutical Biotechnology Excellence Center, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
| | - Praveen Kumar Korla
- Department of Biomedical Informatics, Asia University, Taichung 41354, Taiwan
| | - Naguib Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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Abstract
Insulin is a key hormone controlling metabolic homeostasis. Loss or dysfunction of pancreatic β-cells lead to the release of insufficient insulin to cover the organism needs, promoting diabetes development. Since dietary nutrients influence the activity of β-cells, their inadequate intake, absorption and/or utilisation can be detrimental. This review will highlight the physiological and pathological effects of nutrients on insulin secretion and discuss the underlying mechanisms. Glucose uptake and metabolism in β-cells trigger insulin secretion. This effect of glucose is potentiated by amino acids and fatty acids, as well as by entero-endocrine hormones and neuropeptides released by the digestive tract in response to nutrients. Glucose controls also basal and compensatory β-cell proliferation and, along with fatty acids, regulates insulin biosynthesis. If in the short-term nutrients promote β-cell activities, chronic exposure to nutrients can be detrimental to β-cells and causes reduced insulin transcription, increased basal secretion and impaired insulin release in response to stimulatory glucose concentrations, with a consequent increase in diabetes risk. Likewise, suboptimal early-life nutrition (e.g. parental high-fat or low-protein diet) causes altered β-cell mass and function in adulthood. The mechanisms mediating nutrient-induced β-cell dysfunction include transcriptional, post-transcriptional and translational modifications of genes involved in insulin biosynthesis and secretion, carbohydrate and lipid metabolism, cell differentiation, proliferation and survival. Altered expression of these genes is partly caused by changes in non-coding RNA transcripts induced by unbalanced nutrient uptake. A better understanding of the mechanisms leading to β-cell dysfunction will be critical to improve treatment and find a cure for diabetes.
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Romero-Nava R, Rodriguez JE, Reséndiz-Albor AA, Sánchez-Muñoz F, Ruiz-Hernandéz A, Huang F, Hong E, Villafaña S. Changes in protein and gene expression of angiotensin II receptors (AT1 and AT2) in aorta of diabetic and hypertensive rats. Clin Exp Hypertens 2015; 38:56-62. [PMID: 26268856 DOI: 10.3109/10641963.2015.1060984] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Diabetes and hypertension have been associated with cardiovascular diseases and stroke. Some reports have related the coexistence of hypertension and diabetes with increase in the risk of developing vascular complications. Recently some studies have shown results suggesting that in the early stages of diabetes and hypertension exist a reduced functional response to vasopressor agents like angiotensin II (Ang II), which plays an important role in blood pressure regulation mechanism through the activation of its AT1 and AT2 receptors. For that reason, the aim of this work was to study the gene and protein expression of AT1 and AT2 receptors in aorta of diabetic SHR and WKY rats. Diabetes was induced by the administration of streptozotocin (60 mg/kg i.p.). After 4 weeks of the onset of diabetes, the protein expression was obtained by western blot and the mRNA expression by RT-PCR. Our results showed that the hypertensive rats have a higher mRNA and protein expression of AT1 receptors than normotensive rats while the AT2 expression remained unchanged. On the other hand, the combination of diabetes and hypertension increased the mRNA and protein expression of AT1 and AT2 receptors significantly. In conclusion, our results suggest that diabetes with hypertension modifies the mRNA and protein expression of AT1 and AT2 receptors. However, the overexpression of AT2 could be associated with the reduction in the response to Ang II in the early stage of diabetes.
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Affiliation(s)
- R Romero-Nava
- a Laboratorio de Señalización Intracelular , Sección de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, México D.F. , México
| | - J E Rodriguez
- a Laboratorio de Señalización Intracelular , Sección de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, México D.F. , México
| | - A A Reséndiz-Albor
- a Laboratorio de Señalización Intracelular , Sección de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, México D.F. , México
| | - F Sánchez-Muñoz
- b Departamento de Inmunología , Instituto Nacional de Cardiología Ignacio Chávez, México D.F. , México
| | - A Ruiz-Hernandéz
- a Laboratorio de Señalización Intracelular , Sección de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, México D.F. , México
| | - F Huang
- c Departamento de Farmacología y Toxicología , Hospital Infantil de México Federico Gómez (HIMFG), México D.F. , México , and
| | - E Hong
- d Departamento de Neurofarmacobiología , Centro de Investigación y de Estudios Avanzados, México D.F. , México
| | - S Villafaña
- a Laboratorio de Señalización Intracelular , Sección de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, México D.F. , México
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17
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Cohen M, Kitsberg D, Tsytkin S, Shulman M, Aroeti B, Nahmias Y. Live imaging of GLUT2 glucose-dependent trafficking and its inhibition in polarized epithelial cysts. Open Biol 2014; 4:140091. [PMID: 25056286 PMCID: PMC4118605 DOI: 10.1098/rsob.140091] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/02/2014] [Indexed: 01/20/2023] Open
Abstract
GLUT2 is a facilitative glucose transporter, expressed in polarized epithelial cells of the liver, intestine, kidney and pancreas, where it plays a critical role in glucose homeostasis. Together with SGLT1/2, it mediates glucose absorption in metabolic epithelial tissues, where it can be translocated apically upon high glucose exposure. To track the subcellular localization and dynamics of GLUT2, we created an mCherry-hGLUT2 fusion protein and expressed it in multicellular kidney cysts, a major site of glucose reabsorption. Live imaging of GLUT2 enabled us to avoid the artefactual localization of GLUT2 in fixed cells and to confirm the apical GLUT2 model. Live cell imaging showed a rapid 15 ± 3 min PKC-dependent basal-to-apical translocation of GLUT2 in response to glucose stimulation and a fourfold slower basolateral translocation under starvation. These results mark the physiological importance of responding quickly to rising glucose levels. Importantly, we show that phloretin, an apple polyphenol, inhibits GLUT2 translocation in both directions, suggesting that it exerts its effect by PKC inhibition. Subcellular localization studies demonstrated that GLUT2 is endocytosed through a caveolae-dependent mechanism, and that it is at least partly recovered in Rab11A-positive recycling endosome. Our work illuminates GLUT2 dynamics, providing a platform for drug development for diabetes and hyperglycaemia.
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Affiliation(s)
- Merav Cohen
- Department of Cell and Developmental Biology, Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel Alexander Grass Center for Bioengineering, Benin School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Daniel Kitsberg
- Department of Cell and Developmental Biology, Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel Alexander Grass Center for Bioengineering, Benin School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sabina Tsytkin
- Department of Cell and Developmental Biology, Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maria Shulman
- Department of Cell and Developmental Biology, Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel Alexander Grass Center for Bioengineering, Benin School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Benjamin Aroeti
- Department of Cell and Developmental Biology, Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yaakov Nahmias
- Department of Cell and Developmental Biology, Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel Alexander Grass Center for Bioengineering, Benin School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel
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18
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Bourzac JF, L'Ériger K, Larrivée JF, Arguin G, Bilodeau MS, Stankova J, Gendron FP. Glucose transporter 2 expression is down regulated following P2X7 activation in enterocytes. J Cell Physiol 2012; 228:120-9. [PMID: 22566162 DOI: 10.1002/jcp.24111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
With the diabetes epidemic affecting the world population, there is an increasing demand for means to regulate glycemia. Dietary glucose is first absorbed by the intestine before entering the blood stream. Thus, the regulation of glucose absorption by intestinal epithelial cells (IECs) could represent a way to regulate glycemia. Among the molecules involved in glycemia homeostasis, extracellular ATP, a paracrine signaling molecule, was reported to induce insulin secretion from pancreatic β cells by activating P2Y and P2X receptors. In rat's jejunum, P2X7 expression was previously immunolocalized to the apex of villi, where it has been suspected to play a role in apoptosis. However, using an antibody recognizing the receptor extracellular domain and thus most of the P2X7 isoforms, we showed that expression of this receptor is apparent in the top two-thirds of villi. These data suggest a different role for this receptor in IECs. Using the non-cancerous IEC-6 cells and differentiated Caco-2 cells, glucose transport was reduced by more than 30% following P2X7 stimulation. This effect on glucose transport was not due to P2X7-induced cell apoptosis, but rather was the consequence of glucose transporter 2 (Glut2)'s internalization. The signaling pathway leading to P2X7-dependent Glut2 internalization involved the calcium-independent activation of phospholipase Cγ1 (PLCγ1), PKCδ, and PKD1. Although the complete mechanism regulating Glut2 internalization following P2X7 activation is not fully understood, modulation of P2X7 receptor activation could represent an interesting approach to regulate intestinal glucose absorption.
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Affiliation(s)
- Jean-François Bourzac
- Department of Anatomy and Cell Biology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Mosedale M, Egodage S, Calma RC, Chi NW, Chessler SD. Neurexin-1α contributes to insulin-containing secretory granule docking. J Biol Chem 2012; 287:6350-61. [PMID: 22235116 DOI: 10.1074/jbc.m111.299081] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Neurexins are a family of transmembrane, synaptic adhesion molecules. In neurons, neurexins bind to both sub-plasma membrane and synaptic vesicle-associated constituents of the secretory machinery, play a key role in the organization and stabilization of the presynaptic active zone, and help mediate docking of synaptic vesicles. We have previously shown that neurexins, like many other protein constituents of the neurotransmitter exocytotic machinery, are expressed in pancreatic β cells. We hypothesized that the role of neurexins in β cells parallels their role in neurons, with β-cell neurexins helping to mediate insulin granule docking and secretion. Here we demonstrate that β cells express a more restricted pattern of neurexin transcripts than neurons, with a clear predominance of neurexin-1α expressed in isolated islets. Using INS-1E β cells, we found that neurexin-1α interacts with membrane-bound components of the secretory granule-docking machinery and with the granule-associated protein granuphilin. Decreased expression of neurexin-1α, like decreased expression of granuphilin, reduces granule docking at the β-cell membrane and improves insulin secretion. Perifusion of neurexin-1α KO mouse islets revealed a significant increase in second-phase insulin secretion with a trend toward increased first-phase secretion. Upon glucose stimulation, neurexin-1α protein levels decrease. This glucose-induced down-regulation may enhance glucose-stimulated insulin secretion. We conclude that neurexin-1α is a component of the β-cell secretory machinery and contributes to secretory granule docking, most likely through interactions with granuphilin. Neurexin-1α is the only transmembrane component of the docking machinery identified thus far. Our findings provide new insights into the mechanisms of insulin granule docking and exocytosis.
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Affiliation(s)
- Merrie Mosedale
- Pediatric Diabetes Research Center, Veterans Affairs San Diego Healthcare System, University of California San Diego, La Jolla, California 92093, USA
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20
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Gong Z, Muzumdar RH. Pancreatic function, type 2 diabetes, and metabolism in aging. Int J Endocrinol 2012; 2012:320482. [PMID: 22675349 PMCID: PMC3362843 DOI: 10.1155/2012/320482] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/15/2012] [Accepted: 03/02/2012] [Indexed: 12/21/2022] Open
Abstract
Aging is a risk factor for impaired glucose tolerance and diabetes. Of the reported 25.8 million Americans estimated to have diabetes, 26.9% are over the age of 65. In certain ethnic groups, the proportion is even higher; almost 1 in 3 older Hispanics and African Americans and 3 out of 4 Pima Indian elders have diabetes. As per the NHANES III (Third National Health and Nutrition Examination) survey, the percentage of physician-diagnosed diabetes increased from 3.9% in middle-aged adults (40-49 years) to 13.2% in elderly adults (≥75 years). The higher incidence of diabetes is especially alarming considering that diabetes in itself increases the risk for multiple other age-related diseases such as cancer, stroke, cardiovascular diseases, Parkinson's disease, and Alzheimer's disease (AD). In this review, we summarize the current evidence on how aging affects pancreatic β cell function, β cell mass, insulin secretion and insulin sensitivity. We also review the effects of aging on the relationship between insulin sensitivity and insulin secretion. Understanding the mechanisms that lead to impaired glucose homeostasis and T2D in the elderly will lead to development of novel treatments that will prevent or delay diabetes, substantially improve quality of life and ultimately increase overall life span.
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Affiliation(s)
- Zhenwei Gong
- Department of Pediatrics, Divisions of Endocrinology and Geriatrics, Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Radhika H. Muzumdar
- Department of Pediatrics, Divisions of Endocrinology and Geriatrics, Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Medicine, Divisions of Endocrinology and Geriatrics, Children's Hospital at Montefiore, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
- *Radhika H. Muzumdar:
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Ait-Omar A, Monteiro-Sepulveda M, Poitou C, Le Gall M, Cotillard A, Gilet J, Garbin K, Houllier A, Château D, Lacombe A, Veyrie N, Hugol D, Tordjman J, Magnan C, Serradas P, Clément K, Leturque A, Brot-Laroche E. GLUT2 accumulation in enterocyte apical and intracellular membranes: a study in morbidly obese human subjects and ob/ob and high fat-fed mice. Diabetes 2011; 60:2598-607. [PMID: 21852673 PMCID: PMC3178286 DOI: 10.2337/db10-1740] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE In healthy rodents, intestinal sugar absorption in response to sugar-rich meals and insulin is regulated by GLUT2 in enterocyte plasma membranes. Loss of insulin action maintains apical GLUT2 location. In human enterocytes, apical GLUT2 location has not been reported but may be revealed under conditions of insulin resistance. RESEARCH DESIGN AND METHODS Subcellular location of GLUT2 in jejunal enterocytes was analyzed by confocal and electron microscopy imaging and Western blot in 62 well-phenotyped morbidly obese subjects and 7 lean human subjects. GLUT2 locations were assayed in ob/ob and ob/+ mice receiving oral metformin or in high-fat low-carbohydrate diet-fed C57Bl/6 mice. Glucose absorption and secretion were respectively estimated by oral glucose tolerance test and secretion of [U-(14)C]-3-O-methyl glucose into lumen. RESULTS In human enterocytes, GLUT2 was consistently located in basolateral membranes. Apical GLUT2 location was absent in lean subjects but was observed in 76% of obese subjects and correlated with insulin resistance and glycemia. In addition, intracellular accumulation of GLUT2 with early endosome antigen 1 (EEA1) was associated with reduced MGAT4a activity (glycosylation) in 39% of obese subjects on a low-carbohydrate/high-fat diet. Mice on a low-carbohydrate/high-fat diet for 12 months also exhibited endosomal GLUT2 accumulation and reduced glucose absorption. In ob/ob mice, metformin promoted apical GLUT2 and improved glucose homeostasis. Apical GLUT2 in fasting hyperglycemic ob/ob mice tripled glucose release into intestinal lumen. CONCLUSIONS In morbidly obese insulin-resistant subjects, GLUT2 was accumulated in apical and/or endosomal membranes of enterocytes. Functionally, apical GLUT2 favored and endosomal GLUT2 reduced glucose transepithelial exchanges. Thus, altered GLUT2 locations in enterocytes are a sign of intestinal adaptations to human metabolic pathology.
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Affiliation(s)
- Amal Ait-Omar
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Milena Monteiro-Sepulveda
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Christine Poitou
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Nutrition and Endocrinology Department, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France; Centre Recherche en Nutrition Humaine (CRNH) Ile de France, Paris, France
| | - Maude Le Gall
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Aurélie Cotillard
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Jules Gilet
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Kevin Garbin
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Anne Houllier
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Danièle Château
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Amélie Lacombe
- Centre National de la Recherche Scientifique (EAC4413), Université Paris-Diderot, Paris, France
| | - Nicolas Veyrie
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Surgery Department, Assistance Publique-Hôpitaux de Paris, Hôtel-Dieu Hospital, Paris, France
| | - Danielle Hugol
- Pathology Department, Assistance Publique-Hôpitaux de Paris, Hôtel-Dieu Hospital, Paris, France
| | - Joan Tordjman
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Christophe Magnan
- Centre National de la Recherche Scientifique (EAC4413), Université Paris-Diderot, Paris, France
| | - Patricia Serradas
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Karine Clément
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Nutrition and Endocrinology Department, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France; Centre Recherche en Nutrition Humaine (CRNH) Ile de France, Paris, France
| | - Armelle Leturque
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Edith Brot-Laroche
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Corresponding author: Edith Brot-Laroche,
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Hůlková H, Elleder M. Adipocytes participate in storage in α-galactosidase deficiency (Fabry disease). J Inherit Metab Dis 2010; 33 Suppl 3:S297-300. [PMID: 20628902 PMCID: PMC3757258 DOI: 10.1007/s10545-010-9160-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 06/18/2010] [Accepted: 06/22/2010] [Indexed: 11/06/2022]
Abstract
Ultrastructural and histochemical studies of bioptic and postmortem tissue samples from ten Fabry hemizygotes showed lysosomal storage in adipocytes as a constant feature of the classic phenotype of α-galactosidase (GLA) deficiency. The storage was represented by a crescent-shaped line of storage lysosomes of varying thicknesses restricted to the perinuclear subplasmalemmal area. The ultrastructure of the storage lysosomes was dominated by concentric lipid membranes modified by simultaneous deposition of autofluorescent ceroid. Storage was widely expressed in adipose tissue. The number of storage lysosomes was increased, and the lysosomes were more clustered in adipocytes with less voluminous lipid content. The findings should attract interest to studies of adipose tissue biology in Fabry disease, a topic that has not been studied so far. In terms of cell biology, the observations represent indirect evidence of significant lysosomal turnover of α-galactose lipid conjugates in adipocytes demasked by GLA deficiency. The results extend the thus far limited information on the adipocyte lysosomal system and its participation in lysosomal storage disorders.
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Affiliation(s)
- Helena Hůlková
- Institute of Inherited Metabolic Disorders, Charles University, 1st Faculty of Medicine and Teaching Hospital, Prague, Czech Republic
| | - Milan Elleder
- Institute of Inherited Metabolic Disorders, Charles University, 1st Faculty of Medicine and Teaching Hospital, Prague, Czech Republic
- Institute of Inherited Metabolic Disorders, Division B, Bldg.D, Ke Karlovu 2, 128 08 Prague, Czech Republic
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