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Sherlock BD, Boon MAA, Vlasiou M, Coster ACF. The Distance Between: An Algorithmic Approach to Comparing Stochastic Models to Time-Series Data. Bull Math Biol 2024; 86:111. [PMID: 39060776 PMCID: PMC11282162 DOI: 10.1007/s11538-024-01331-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 06/21/2024] [Indexed: 07/28/2024]
Abstract
While mean-field models of cellular operations have identified dominant processes at the macroscopic scale, stochastic models may provide further insight into mechanisms at the molecular scale. In order to identify plausible stochastic models, quantitative comparisons between the models and the experimental data are required. The data for these systems have small sample sizes and time-evolving distributions. The aim of this study is to identify appropriate distance metrics for the quantitative comparison of stochastic model outputs and time-evolving stochastic measurements of a system. We identify distance metrics with features suitable for driving parameter inference, model comparison, and model validation, constrained by data from multiple experimental protocols. In this study, stochastic model outputs are compared to synthetic data across three scales: that of the data at the points the system is sampled during the time course of each type of experiment; a combined distance across the time course of each experiment; and a combined distance across all the experiments. Two broad categories of comparators at each point were considered, based on the empirical cumulative distribution function (ECDF) of the data and of the model outputs: discrete based measures such as the Kolmogorov-Smirnov distance, and integrated measures such as the Wasserstein-1 distance between the ECDFs. It was found that the discrete based measures were highly sensitive to parameter changes near the synthetic data parameters, but were largely insensitive otherwise, whereas the integrated distances had smoother transitions as the parameters approached the true values. The integrated measures were also found to be robust to noise added to the synthetic data, replicating experimental error. The characteristics of the identified distances provides the basis for the design of an algorithm suitable for fitting stochastic models to real world stochastic data.
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Affiliation(s)
- Brock D Sherlock
- School of Mathematics and Statistics, University of New South Wales, Sydney, NSW, 2052, Australia
- Department of Mathematics and Computer Science, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Marko A A Boon
- Department of Mathematics and Computer Science, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Maria Vlasiou
- Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Adelle C F Coster
- School of Mathematics and Statistics, University of New South Wales, Sydney, NSW, 2052, Australia.
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2
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Geiser A, Foylan S, Tinning PW, Bryant NJ, Gould GW. GLUT4 dispersal at the plasma membrane of adipocytes: a super-resolved journey. Biosci Rep 2023; 43:BSR20230946. [PMID: 37791639 PMCID: PMC10600063 DOI: 10.1042/bsr20230946] [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: 09/07/2023] [Revised: 10/03/2023] [Accepted: 10/04/2023] [Indexed: 10/05/2023] Open
Abstract
In adipose tissue, insulin stimulates glucose uptake by mediating the translocation of GLUT4 from intracellular vesicles to the plasma membrane. In 2010, insulin was revealed to also have a fundamental impact on the spatial distribution of GLUT4 within the plasma membrane, with the existence of two GLUT4 populations at the plasma membrane being defined: (1) as stationary clusters and (2) as diffusible monomers. In this model, in the absence of insulin, plasma membrane-fused GLUT4 are found to behave as clusters. These clusters are thought to arise from exocytic events that retain GLUT4 at their fusion sites; this has been proposed to function as an intermediate hub between GLUT4 exocytosis and re-internalisation. By contrast, insulin stimulation induces the dispersal of GLUT4 clusters into monomers and favours a distinct type of GLUT4-vesicle fusion event, known as fusion-with-release exocytosis. Here, we review how super-resolution microscopy approaches have allowed investigation of the characteristics of plasma membrane-fused GLUT4 and further discuss regulatory step(s) involved in the GLUT4 dispersal machinery, introducing the scaffold protein EFR3 which facilitates localisation of phosphatidylinositol 4-kinase type IIIα (PI4KIIIα) to the cell surface. We consider how dispersal may be linked to the control of transporter activity, consider whether macro-organisation may be a widely used phenomenon to control proteins within the plasma membrane, and speculate on the origin of different forms of GLUT4-vesicle exocytosis.
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Affiliation(s)
- Angéline Geiser
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - Shannan Foylan
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - Peter W Tinning
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - Nia J Bryant
- Department of Biology, University of York, Heslington, York, U.K
| | - Gwyn W Gould
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
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3
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Matsui K, Emoto M, Fukuda N, Nomiyama R, Yamada K, Tanizawa Y. SNARE-binding protein synaptosomal-associated protein of 29 kDa (SNAP29) regulates the intracellular sequestration of glucose transporter 4 (GLUT4) vesicles in adipocytes. J Diabetes Investig 2022; 14:19-27. [PMID: 36181414 PMCID: PMC9807150 DOI: 10.1111/jdi.13912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 08/16/2022] [Accepted: 09/07/2022] [Indexed: 01/07/2023] Open
Abstract
AIMS/INTRODUCTION Insulin stimulates translocation of glucose transporter 4 (GLUT4) from the perinuclear location to the plasma membrane. In the unstimulated state, intracellular vesicles containing GLUT4 are sequestered into specialized storage vesicles that have come to be known as the insulin-responsive compartment (IRC). The IRC is a functional compartment in the perinuclear region that is a target of the insulin signaling cascade, although its precise nature is unclear. Here, we report a novel molecular mechanism facilitating formation of the IRC. MATERIALS AND METHODS We determined synaptosomal-associated protein of 29 kDa (SNAP29) by mass spectrometry to be an EH domain-containing protein 1 (EHD1)-binding protein. Then, its expression was confirmed by western blotting. Subcellular localization of SNAP29 was determined by immunofluorescent microscopy. Interactions between SNAP29 and syntaxins were determined by immunoprecipitation. We measured glucose uptake and GLUT4 translocation in 3T3-L1 adipocyte expressing SNAP29 or silencing SNAP29. RESULTS We found SNAP29 to be localized in the perinuclear region and to show partial co-localization with GLUT4 under basal conditions. We also found that SNAP29 binds to syntaxin6, a Qc-SNARE, in adipocytes. In SNAP29-expressing cells, vesicles containing GLUT4 were observed to aggregate around the perinuclear region. In contrast, when SNAP29 was silenced, perinuclear GLUT4 vesicles were dispersed throughout the cytosol. Insulin-stimulated glucose uptake was inhibited in both SNAP29-expressing and SNAP29-silenced cells. CONCLUSIONS These data suggest that SNAP29 sequesters and anchors GLUT4-containing vesicles in the perinuclear region, and might have a role in the biogenesis of the perinuclear IRC.
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Affiliation(s)
- Kumiko Matsui
- Department of Endocrinology, Metabolism, Hematological Sciences and TherapeuticsYamaguchi University Graduate School of MedicineUbeJapan
| | - Masahiro Emoto
- Department of Endocrinology, Metabolism, Hematological Sciences and TherapeuticsYamaguchi University Graduate School of MedicineUbeJapan,Emoto ClinicUbeJapan
| | - Naofumi Fukuda
- Department of Endocrinology, Metabolism, Hematological Sciences and TherapeuticsYamaguchi University Graduate School of MedicineUbeJapan
| | - Ryuta Nomiyama
- Department of Endocrinology, Metabolism, Hematological Sciences and TherapeuticsYamaguchi University Graduate School of MedicineUbeJapan
| | - Kyoko Yamada
- Department of Endocrinology, Metabolism, Hematological Sciences and TherapeuticsYamaguchi University Graduate School of MedicineUbeJapan
| | - Yukio Tanizawa
- Department of Endocrinology, Metabolism, Hematological Sciences and TherapeuticsYamaguchi University Graduate School of MedicineUbeJapan
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4
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Fazakerley DJ, Koumanov F, Holman GD. GLUT4 On the move. Biochem J 2022; 479:445-462. [PMID: 35147164 PMCID: PMC8883492 DOI: 10.1042/bcj20210073] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 01/11/2022] [Accepted: 01/14/2022] [Indexed: 12/16/2022]
Abstract
Insulin rapidly stimulates GLUT4 translocation and glucose transport in fat and muscle cells. Signals from the occupied insulin receptor are translated into downstream signalling changes in serine/threonine kinases within timescales of seconds, and this is followed by delivery and accumulation of the glucose transporter GLUT4 at the plasma membrane. Kinetic studies have led to realisation that there are distinct phases of this stimulation by insulin. There is a rapid initial burst of GLUT4 delivered to the cell surface from a subcellular reservoir compartment and this is followed by a steady-state level of continuing stimulation in which GLUT4 recycles through a large itinerary of subcellular locations. Here, we provide an overview of the phases of insulin stimulation of GLUT4 translocation and the molecules that are currently considered to activate these trafficking steps. Furthermore, we suggest how use of new experimental approaches together with phospho-proteomic data may help to further identify mechanisms for activation of these trafficking processes.
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Affiliation(s)
- Daniel J Fazakerley
- Metabolic Research Laboratories, Wellcome-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, U.K
| | - Francoise Koumanov
- Department for Health, Centre for Nutrition, Exercise, and Metabolism, University of Bath, Bath, Somerset BA2 7AY, U.K
| | - Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, Bath, Somerset BA2 7AY, U.K
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5
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Rawat A, Morrison BM. Metabolic Transporters in the Peripheral Nerve-What, Where, and Why? Neurotherapeutics 2021; 18:2185-2199. [PMID: 34773210 PMCID: PMC8804006 DOI: 10.1007/s13311-021-01150-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 12/18/2022] Open
Abstract
Cellular metabolism is critical not only for cell survival, but also for cell fate, function, and intercellular communication. There are several different metabolic transporters expressed in the peripheral nervous system, and they each play important roles in maintaining cellular energy. The major source of energy in the peripheral nervous system is glucose, and glucose transporters 1 and 3 are expressed and allow blood glucose to be imported and utilized by peripheral nerves. There is also increasing evidence that other sources of energy, particularly monocarboxylates such as lactate that are transported primarily by monocarboxylate transporters 1 and 2 in peripheral nerves, can be efficiently utilized by peripheral nerves. Finally, emerging evidence supports an important role for connexins and possibly pannexins in the supply and regulation of metabolic energy. In this review, we will first define these critical metabolic transporter subtypes and then examine their localization in the peripheral nervous system. We will subsequently discuss the evidence, which comes both from experiments in animal models and observations from human diseases, supporting critical roles played by these metabolic transporters in the peripheral nervous system. Despite progress made in understanding the function of these transporters, many questions and some discrepancies remain, and these will also be addressed throughout this review. Peripheral nerve metabolism is fundamentally important and renewed interest in these pathways should help to answer many of these questions and potentially provide new treatments for neurologic diseases that are partly, or completely, caused by disruption of metabolism.
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Affiliation(s)
- Atul Rawat
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Brett M Morrison
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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6
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Holman GD. Structure, function and regulation of mammalian glucose transporters of the SLC2 family. Pflugers Arch 2020; 472:1155-1175. [PMID: 32591905 PMCID: PMC7462842 DOI: 10.1007/s00424-020-02411-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 12/12/2022]
Abstract
The SLC2 genes code for a family of GLUT proteins that are part of the major facilitator superfamily (MFS) of membrane transporters. Crystal structures have recently revealed how the unique protein fold of these proteins enables the catalysis of transport. The proteins have 12 transmembrane spans built from a replicated trimer substructure. This enables 4 trimer substructures to move relative to each other, and thereby alternately opening and closing a cleft to either the internal or the external side of the membrane. The physiological substrate for the GLUTs is usually a hexose but substrates for GLUTs can include urate, dehydro-ascorbate and myo-inositol. The GLUT proteins have varied physiological functions that are related to their principal substrates, the cell type in which the GLUTs are expressed and the extent to which the proteins are associated with subcellular compartments. Some of the GLUT proteins translocate between subcellular compartments and this facilitates the control of their function over long- and short-time scales. The control of GLUT function is necessary for a regulated supply of metabolites (mainly glucose) to tissues. Pathophysiological abnormalities in GLUT proteins are responsible for, or associated with, clinical problems including type 2 diabetes and cancer and a range of tissue disorders, related to tissue-specific GLUT protein profiles. The availability of GLUT crystal structures has facilitated the search for inhibitors and substrates and that are specific for each GLUT and that can be used therapeutically. Recent studies are starting to unravel the drug targetable properties of each of the GLUT proteins.
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Affiliation(s)
- Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK.
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7
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D'Alessandro R, Meldolesi J. News about non-secretory exocytosis: mechanisms, properties, and functions. J Mol Cell Biol 2020; 11:736-746. [PMID: 30605539 PMCID: PMC6821209 DOI: 10.1093/jmcb/mjy084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 11/14/2018] [Accepted: 01/02/2019] [Indexed: 12/22/2022] Open
Abstract
The fusion by exocytosis of many vesicles to the plasma membrane induces the discharge to the extracellular space of their abundant luminal cargoes. Other exocytic vesicles, however, do not contain cargoes, and thus, their fusion is not followed by secretion. Therefore, two distinct processes of exocytosis exist, one secretory and the other non-secretory. The present review deals with the knowledge of non-secretory exocytosis developed during recent years. Among such developments are the dual generation of the exocytic vesicles, initially released either from the trans-Golgi network or by endocytosis; their traffic with activation of receptors, channels, pumps, and transporters; the identification of their tethering and soluble N-ethylmaleimide-sensitive factor attachment protein receptor complexes that govern membrane fusions; the growth of axons and the membrane repair. Examples of potential relevance of these processes for pathology and medicine are also reported. The developments presented here offer interesting chances for future progress in the field.
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Affiliation(s)
| | - Jacopo Meldolesi
- Scientific Institute San Raffaele and Vita Salute San Raffaele University, Via Olgettina 58, Milan, Italy
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8
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Liu Z, Xu L, Xing M, Xu X, Wei J, Wang J, Kang W. Trelagliptin succinate: DPP-4 inhibitor to improve insulin resistance in adipocytes. Biomed Pharmacother 2020; 125:109952. [PMID: 32036216 DOI: 10.1016/j.biopha.2020.109952] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 01/18/2020] [Accepted: 01/23/2020] [Indexed: 02/07/2023] Open
Abstract
Trelagliptin inhibits the enzyme dipeptidyl-4 (DPP-4) to treat type 2 diabetes and it may possess the potential to improve insulin resistance. However, the molecular mechanism is not known. In this study, the effect of trelagliptin succinate in improving insulin resistance was investigated. The differentiation system of 3T3-L1 mouse preadipocytes was used to determine the content of adipokines and the content of GLUT4 in the outer membrane. The expression of AKT, P-AKT, IRS-1 and P-IRS-1 in differentiated 3T3-L1 adipocytes was determined by western blotting. Our results demonstrated that trelagliptin succinate increased the expression of AKT, P-AKT, IRS-1 and P-IRS-1 in the PI-3K/AKT insulin signaling pathway. These events promote the trans-membrane function of GLUT4 and concomitant glucose intake in adipocytes. In addition, the secretion of free fatty acids and resistin were decreased. In conclusion, our study suggested that trelagliptin succinate improved insulin resistance in adipocytes via regulation of PI-3K/AKT/GLUT4 insulin signaling pathway.
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Affiliation(s)
- Zhenhua Liu
- National R & D Center for Edible Fungus Processing Technology, Henan University, Kaifeng 475004, China; Joint International Research Laboratory of Food & Medicine Resource Function, Henan Province, Kaifeng 475004, China
| | - Lanting Xu
- National R & D Center for Edible Fungus Processing Technology, Henan University, Kaifeng 475004, China; Joint International Research Laboratory of Food & Medicine Resource Function, Henan Province, Kaifeng 475004, China
| | - Meimei Xing
- National R & D Center for Edible Fungus Processing Technology, Henan University, Kaifeng 475004, China; Joint International Research Laboratory of Food & Medicine Resource Function, Henan Province, Kaifeng 475004, China
| | - Xiaojie Xu
- Zhengzhou Mingze Pharmaceutical Technology Co., Ltd. Zhengzhou, 450000, China
| | - Jinfeng Wei
- National R & D Center for Edible Fungus Processing Technology, Henan University, Kaifeng 475004, China; Joint International Research Laboratory of Food & Medicine Resource Function, Henan Province, Kaifeng 475004, China
| | - Jinmei Wang
- National R & D Center for Edible Fungus Processing Technology, Henan University, Kaifeng 475004, China; Joint International Research Laboratory of Food & Medicine Resource Function, Henan Province, Kaifeng 475004, China.
| | - Wenyi Kang
- National R & D Center for Edible Fungus Processing Technology, Henan University, Kaifeng 475004, China; Joint International Research Laboratory of Food & Medicine Resource Function, Henan Province, Kaifeng 475004, China.
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9
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Abstract
A pivotal metabolic function of insulin is the stimulation of glucose uptake into muscle and adipose tissues. The discovery of the insulin-responsive glucose transporter type 4 (GLUT4) protein in 1988 inspired its molecular cloning in the following year. It also spurred numerous cellular mechanistic studies laying the foundations for how insulin regulates glucose uptake by muscle and fat cells. Here, we reflect on the importance of the GLUT4 discovery and chronicle additional key findings made in the past 30 years. That exocytosis of a multispanning membrane protein regulates cellular glucose transport illuminated a novel adaptation of the secretory pathway, which is to transiently modulate the protein composition of the cellular plasma membrane. GLUT4 controls glucose transport into fat and muscle tissues in response to insulin and also into muscle during exercise. Thus, investigation of regulated GLUT4 trafficking provides a major means by which to map the essential signaling components that transmit the effects of insulin and exercise. Manipulation of the expression of GLUT4 or GLUT4-regulating molecules in mice has revealed the impact of glucose uptake on whole-body metabolism. Remaining gaps in our understanding of GLUT4 function and regulation are highlighted here, along with opportunities for future discoveries and for the development of therapeutic approaches to manage metabolic disease.
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Affiliation(s)
- Amira Klip
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Timothy E McGraw
- Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10065
| | - David E James
- Charles Perkins Centre, School of Life and Environmental Sciences, Sydney Medical School, University of Sydney, Camperdown, New South Wales 2050, Australia
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10
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Sousa Fialho MDL, Abd Jamil AH, Stannard GA, Heather LC. Hypoxia-inducible factor 1 signalling, metabolism and its therapeutic potential in cardiovascular disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:831-843. [DOI: 10.1016/j.bbadis.2018.09.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/24/2018] [Accepted: 09/18/2018] [Indexed: 12/20/2022]
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11
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Chemical biology probes of mammalian GLUT structure and function. Biochem J 2018; 475:3511-3534. [PMID: 30459202 PMCID: PMC6243331 DOI: 10.1042/bcj20170677] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/11/2018] [Accepted: 10/11/2018] [Indexed: 12/14/2022]
Abstract
The structure and function of glucose transporters of the mammalian GLUT family of proteins has been studied over many decades, and the proteins have fascinated numerous research groups over this time. This interest is related to the importance of the GLUTs as archetypical membrane transport facilitators, as key limiters of the supply of glucose to cell metabolism, as targets of cell insulin and exercise signalling and of regulated membrane traffic, and as potential drug targets to combat cancer and metabolic diseases such as type 2 diabetes and obesity. This review focusses on the use of chemical biology approaches and sugar analogue probes to study these important proteins.
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12
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Bergqvist N, Nyman E, Cedersund G, Stenkula KG. A systems biology analysis connects insulin receptor signaling with glucose transporter translocation in rat adipocytes. J Biol Chem 2017; 292:11206-11217. [PMID: 28495883 DOI: 10.1074/jbc.m117.787515] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/03/2017] [Indexed: 12/26/2022] Open
Abstract
Type 2 diabetes is characterized by insulin resistance, which arises from malfunctions in the intracellular insulin signaling network. Knowledge of the insulin signaling network is fragmented, and because of the complexity of this network, little consensus has emerged for the structure and importance of the different branches of the network. To help overcome this complexity, systems biology mathematical models have been generated for predicting both the activation of the insulin receptor (IR) and the redistribution of glucose transporter 4 (GLUT4) to the plasma membrane. Although the insulin signal transduction between IR and GLUT4 has been thoroughly studied with modeling and time-resolved data in human cells, comparable analyses in cells from commonly used model organisms such as rats and mice are lacking. Here, we combined existing data and models for rat adipocytes with new data collected for the signaling network between IR and GLUT4 to create a model also for their interconnections. To describe all data (>140 data points), the model needed three distinct pathways from IR to GLUT4: (i) via protein kinase B (PKB) and Akt substrate of 160 kDa (AS160), (ii) via an AS160-independent pathway from PKB, and (iii) via an additional pathway from IR, e.g. affecting the membrane constitution. The developed combined model could describe data not used for training the model and was used to generate predictions of the relative contributions of the pathways from IR to translocation of GLUT4. The combined model provides a systems-level understanding of insulin signaling in rat adipocytes, which, when combined with corresponding models for human adipocytes, may contribute to model-based drug development for diabetes.
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Affiliation(s)
| | - Elin Nyman
- From the Departments of Biomedical Engineering and.,Cardiovascular and Metabolic Diseases Innovative Medicines and Early Development Biotech Unit, AstraZeneca R&D, SE431 83 Gothenburg, Sweden, and
| | - Gunnar Cedersund
- From the Departments of Biomedical Engineering and .,Clinical and Experimental Medicine and Biomedical Engineering, Linköping University, SE581 85 Linköping, Sweden
| | - Karin G Stenkula
- Glucose Transport and Protein Trafficking, Department of Experimental Medical Sciences, Biomedical Centre, Lund University, SE221 84 Lund, Sweden
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13
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Defries DM, Taylor CG, Zahradka P. GLUT3 is present in Clone 9 liver cells and translocates to the plasma membrane in response to insulin. Biochem Biophys Res Commun 2016; 477:433-9. [PMID: 27320866 DOI: 10.1016/j.bbrc.2016.06.081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 06/15/2016] [Indexed: 11/29/2022]
Abstract
Clone 9 cells have been reported to express only the GLUT1 facilitative glucose transporter; however, previous studies have not examined Clone 9 cells for GLUT3 content. The current study sought to profile the presence of glucose transporters in Clone 9 cells, H4IIE hepatoma cells, and L6 myoblasts and myotubes. While the other cell types contained the expected complement of transporters, Clone 9 cells had GLUT3 which was previously not reported. Interestingly, both GLUT3 mRNA and protein were detected in Clone 9 cells, but only mRNA for GLUT1 was detected. Glucose transport in Clone 9 cells was insulin-sensitive in a concentration-dependent manner, concomitant with the presence of GLUT3 in the plasma membrane after insulin treatment. Although basal glucose uptake was unaffected, insulin-stimulated glucose uptake was abolished with siRNA-mediated GLUT3 knockdown. These results contradict previous reports that Clone 9 cells exclusively express GLUT1 and suggest GLUT3 is a key insulin-sensitive glucose transporter required for insulin-stimulated glucose uptake by Clone 9 cells.
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Affiliation(s)
- Danielle M Defries
- Department of Human Nutritional Sciences, University of Manitoba, 209 Human Ecology Building, Winnipeg, Manitoba R3T 292, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, Manitoba R2H 2A6, Canada; Department of Kinesiology and Applied Health, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba R3B 2E9, Canada.
| | - Carla G Taylor
- Department of Human Nutritional Sciences, University of Manitoba, 209 Human Ecology Building, Winnipeg, Manitoba R3T 292, Canada; Department of Physiology and Pathophysiology, University of Manitoba, 432 Basic Medical Sciences Building, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, Manitoba R2H 2A6, Canada.
| | - Peter Zahradka
- Department of Human Nutritional Sciences, University of Manitoba, 209 Human Ecology Building, Winnipeg, Manitoba R3T 292, Canada; Department of Physiology and Pathophysiology, University of Manitoba, 432 Basic Medical Sciences Building, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, Manitoba R2H 2A6, Canada.
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14
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Vazirani RP, Verma A, Sadacca LA, Buckman MS, Picatoste B, Beg M, Torsitano C, Bruno JH, Patel RT, Simonyte K, Camporez JP, Moreira G, Falcone DJ, Accili D, Elemento O, Shulman GI, Kahn BB, McGraw TE. Disruption of Adipose Rab10-Dependent Insulin Signaling Causes Hepatic Insulin Resistance. Diabetes 2016; 65:1577-89. [PMID: 27207531 PMCID: PMC4878419 DOI: 10.2337/db15-1128] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 03/21/2016] [Indexed: 12/31/2022]
Abstract
Insulin controls glucose uptake into adipose and muscle cells by regulating the amount of GLUT4 in the plasma membrane. The effect of insulin is to promote the translocation of intracellular GLUT4 to the plasma membrane. The small Rab GTPase, Rab10, is required for insulin-stimulated GLUT4 translocation in cultured 3T3-L1 adipocytes. Here we demonstrate that both insulin-stimulated glucose uptake and GLUT4 translocation to the plasma membrane are reduced by about half in adipocytes from adipose-specific Rab10 knockout (KO) mice. These data demonstrate that the full effect of insulin on adipose glucose uptake is the integrated effect of Rab10-dependent and Rab10-independent pathways, establishing a divergence in insulin signal transduction to the regulation of GLUT4 trafficking. In adipose-specific Rab10 KO female mice, the partial inhibition of stimulated glucose uptake in adipocytes induces insulin resistance independent of diet challenge. During euglycemic-hyperinsulinemic clamp, there is no suppression of hepatic glucose production despite normal insulin suppression of plasma free fatty acids. The impact of incomplete disruption of stimulated adipocyte GLUT4 translocation on whole-body glucose homeostasis is driven by a near complete failure of insulin to suppress hepatic glucose production rather than a significant inhibition in muscle glucose uptake. These data underscore the physiological significance of the precise control of insulin-regulated trafficking in adipocytes.
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Affiliation(s)
- Reema P Vazirani
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | - Akanksha Verma
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY
| | - L Amanda Sadacca
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | - Melanie S Buckman
- Department of Cardiothoracic Surgery, Weill Cornell Medical College, New York, NY
| | - Belen Picatoste
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | - Muheeb Beg
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | | | - Joanne H Bruno
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | - Rajesh T Patel
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | - Kotryna Simonyte
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Joao P Camporez
- Departments of Internal Medicine and Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT
| | - Gabriela Moreira
- Departments of Internal Medicine and Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT
| | | | - Domenico Accili
- Department of Medicine and Naomi Berrie Diabetes Center, Columbia University, New York, NY
| | - Olivier Elemento
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY
| | - Gerald I Shulman
- Department of Pathology, Weill Cornell Medical College, New York, NY Howard Hughes Medical Institute, Yale University, New Haven, CT
| | - Barbara B Kahn
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Timothy E McGraw
- Department of Biochemistry, Weill Cornell Medical College, New York, NY Department of Cardiothoracic Surgery, Weill Cornell Medical College, New York, NY
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15
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Khalique A, Sarwade RD, Pandey PR, Vijayakumar MV, Bhat MK, Seshadri V. Prolonged exposure to insulin with insufficient glucose leads to impaired Glut4 translocation. Biochem Biophys Res Commun 2016; 474:64-70. [PMID: 27105912 DOI: 10.1016/j.bbrc.2016.04.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 04/13/2016] [Indexed: 11/29/2022]
Abstract
Insulin maintains glucose homeostasis by stimulating glucose uptake from extracellular environment to adipose and muscle tissue through glucose transporter (GLUT4). Insulin resistance plays a significant role in pathologies associated with type2 diabetes. It has been previously shown that hyperinsulinemia can lead to insulin resistance. In these studies very high levels of insulin was used to achieve insulin resistance. We hypothesized that one of the causes of type 2 diabetes could be insulin synthesis in the absence of glucose stimulation. We used CHO cell line, stably expressing Myc-GLUT4-GFP along with human insulin receptor to study the effect of hyperinsulinemia in the presence of low glucose (6.5 mM) or high glucose (20 mM). The insulin responsiveness of these cells was assessed by FRAP, FACS and subcellular fractionation. The results suggest that exposure of cells to insulin in low glucose conditions made these cells insulin resistant within 10 passages, while the same level of insulin in the presence of high glucose did not result in insulin resistance. These results clearly suggest that hyperinsulinemia combined with hypoglycaemia may lead to insulin resistance and may be one of the causes for the typ2 diabetes.
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Affiliation(s)
- Abdul Khalique
- Biotechnology Department, Savitribai Phule Pune University, Pune 411007 India; National Centre for Cell Science, Pune 411007 India
| | - Rucha D Sarwade
- Biotechnology Department, Savitribai Phule Pune University, Pune 411007 India; National Centre for Cell Science, Pune 411007 India
| | - Poonam R Pandey
- Biotechnology Department, Savitribai Phule Pune University, Pune 411007 India; National Centre for Cell Science, Pune 411007 India
| | | | - Manoj K Bhat
- National Centre for Cell Science, Pune 411007 India
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16
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Brewer PD, Habtemichael EN, Romenskaia I, Mastick CC, Coster ACF. Insulin-regulated Glut4 translocation: membrane protein trafficking with six distinctive steps. J Biol Chem 2014; 289:17280-98. [PMID: 24778187 DOI: 10.1074/jbc.m114.555714] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The trafficking kinetics of Glut4, the transferrin (Tf) receptor, and LRP1 were quantified in adipocytes and undifferentiated fibroblasts. Six steps were identified that determine steady state cell surface Glut4: (i) endocytosis, (ii) degradation, (iii) sorting, (iv) sequestration, (v) release, and (vi) tethering/docking/fusion. Endocytosis of Glut4 is 3 times slower than the Tf receptor in fibroblasts (ken = 0.2 min(-1) versus 0.6 min(-1)). Differentiation decreases Glut4 ken 40% (ken = 0.12 min(-1)). Differentiation also decreases Glut4 degradation, increasing total and cell surface Glut4 3-fold. In fibroblasts, Glut4 is recycled from endosomes through a slow constitutive pathway (kex = 0.025-0.038 min(-1)), not through the fast Tf receptor pathway (kex = 0.2 min(-1)). The kex measured in adipocytes after insulin stimulation is similar (kex = 0.027 min(-1)). Differentiation decreases the rate constant for sorting into the Glut4 recycling pathway (ksort) 3-fold. In adipocytes, Glut4 is also sorted from endosomes into a second exocytic pathway through Glut4 storage vesicles (GSVs). Surprisingly, transfer from endosomes into GSVs is highly regulated; insulin increases the rate constant for sequestration (kseq) 8-fold. Release from sequestration in GSVs is rate-limiting for Glut4 exocytosis in basal adipocytes. AS160 regulates this step. Tethering/docking/fusion of GSVs to the plasma membrane is regulated through an AS160-independent process. Insulin increases the rate of release and fusion of GSVs (kfuseG) 40-fold. LRP1 cycles with the Tf receptor and Glut4 in fibroblasts but predominantly with Glut4 after differentiation. Surprisingly, AS160 knockdown accelerated LRP1 exocytosis in basal and insulin-stimulated adipocytes. These data indicate that AS160 may regulate trafficking into as well as release from GSVs.
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Affiliation(s)
- Paul Duffield Brewer
- From the Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557
| | - Estifanos N Habtemichael
- the Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, and
| | - Irina Romenskaia
- From the Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557
| | - Cynthia Corley Mastick
- From the Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557,
| | - Adelle C F Coster
- the School of Mathematics and Statistics, University of New South Wales, Sydney, New South Wales 2052, Australia
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17
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Abstract
Insulin regulates glucose uptake by controlling the subcellular location of GLUT4 glucose transporters. GLUT4 is sequestered within fat and muscle cells during low-insulin states, and is translocated to the cell surface upon insulin stimulation. The TUG protein is a functional tether that sequesters GLUT4 at the Golgi matrix. To stimulate glucose uptake, insulin triggers TUG endoproteolytic cleavage. Cleavage accounts for a large proportion of the acute effect of insulin to mobilize GLUT4 to the cell surface. During ongoing insulin exposure, endocytosed GLUT4 recycles to the plasma membrane directly from endosomes, and bypasses a TUG-regulated trafficking step. Insulin acts through the TC10α GTPase and its effector protein, PIST, to stimulate TUG cleavage. This action is coordinated with insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases, and with other signals to direct overall GLUT4 targeting. Data support the idea that the N-terminal TUG cleavage product, TUGUL, functions as a novel ubiquitin-like protein modifier to facilitate GLUT4 movement to the cell surface. The C-terminal TUG cleavage product is extracted from the Golgi matrix, which vacates an "anchoring" site to permit subsequent cycles of GLUT4 retention and release. Together, GLUT4 vesicle translocation and TUG cleavage may coordinate glucose uptake with physiologic effects of other proteins present in the GLUT4-containing vesicles, and with potential additional effects of the TUG C-terminal product. Understanding this TUG pathway for GLUT4 retention and release will shed light on the regulation of glucose uptake and the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Jonathan P Belman
- Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, Box 208020, New Haven, CT, 06520-8020, USA
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18
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Olson AL. Regulation of GLUT4 and Insulin-Dependent Glucose Flux. ISRN MOLECULAR BIOLOGY 2012; 2012:856987. [PMID: 27335671 PMCID: PMC4890881 DOI: 10.5402/2012/856987] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 09/24/2012] [Indexed: 12/21/2022]
Abstract
GLUT4 has long been known to be an insulin responsive glucose transporter. Regulation of GLUT4 has been a major focus of research on the cause and prevention of type 2 diabetes. Understanding how insulin signaling alters the intracellular trafficking of GLUT4 as well as understanding the fate of glucose transported into the cell by GLUT4 will be critically important for seeking solutions to the current rise in diabetes and metabolic disease.
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Affiliation(s)
- Ann Louise Olson
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, P.O. Box 26901, BMSB 964, Oklahoma City, OK 73190, USA
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19
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Lizunov VA, Stenkula KG, Lisinski I, Gavrilova O, Yver DR, Chadt A, Al-Hasani H, Zimmerberg J, Cushman SW. Insulin stimulates fusion, but not tethering, of GLUT4 vesicles in skeletal muscle of HA-GLUT4-GFP transgenic mice. Am J Physiol Endocrinol Metab 2012; 302:E950-60. [PMID: 22297303 PMCID: PMC3330721 DOI: 10.1152/ajpendo.00466.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Insulin regulates glucose uptake into fat and muscle by modulating the subcellular distribution of GLUT4 between the cell surface and intracellular compartments. However, quantification of these translocation processes in muscle by classical subcellular fractionation techniques is confounded by contaminating microfibrillar protein; dynamic studies at the molecular level are almost impossible. In this study, we introduce a muscle-specific transgenic mouse model in which HA-GLUT4-GFP is expressed under the control of the MCK promoter. HA-GLUT4-GFP was found to translocate to the plasma membrane and T-tubules after insulin stimulation, thus mimicking endogenous GLUT4. To investigate the dynamics of GLUT4 trafficking in skeletal muscle, we quantified vesicles containing HA-GLUT4-GFP near the sarcolemma and T-tubules and analyzed insulin-stimulated exocytosis at the single vesicle level by total internal reflection fluorescence and confocal microscopy. We found that only 10% of the intracellular GLUT4 pool comprised mobile vesicles, whereas most of the GLUT4 structures remained stationary or tethered at the sarcolemma or T-tubules. In fact, most of the insulin-stimulated exocytosis emanated from pretethered vesicles, whereas the small pool of mobile GLUT4 vesicles was not significantly affected by insulin. Our data strongly suggest that the mobile pool of GLUT4 vesicles is not a major site of insulin action but rather locally distributed. Most likely, pretethered GLUT4 structures are responsible for the initial phase of insulin-stimulated exocytosis.
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Affiliation(s)
- Vladimir A Lizunov
- Program in Physical Biology, National Institute of Child Health and Human Development/National Institutes of Health, Bethesda, MD, USA
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20
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Abstract
To enhance glucose uptake into muscle and fat cells, insulin stimulates the translocation of GLUT4 glucose transporters from intracellular membranes to the cell surface. This response requires the intersection of insulin signaling and vesicle trafficking pathways, and it is compromised in the setting of overnutrition to cause insulin resistance. Insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases and through the Rho GTPase TC10α to act on other targets. In unstimulated cells, GLUT4 is incorporated into specialized storage vesicles containing IRAP, LRP1, sortilin, and VAMP2, which are sequestered by TUG, Ubc9, and other proteins. Insulin mobilizes these vesicles directly to the plasma membrane, and it modulates the trafficking itinerary so that cargo recycles from endosomes during ongoing insulin exposure. Knowledge of how signaling and trafficking pathways are coordinated will be essential to understanding the pathogenesis of diabetes and the metabolic syndrome and may also inform a wide range of other physiologies.
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Affiliation(s)
- Jonathan S Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA.
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21
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STAGSTED JAN. Journey beyond immunology. Regulation of receptor internalization by major histocompatibility complex class I (MHC-I) and effect of peptides derived from MHC-I. APMIS 2011. [DOI: 10.1111/j.1600-0463.1998.tb05657.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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22
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Stöckli J, Fazakerley DJ, Coster ACF, Holman GD, James DE. Muscling in on GLUT4 kinetics. Commun Integr Biol 2011; 3:260-2. [PMID: 20714409 DOI: 10.4161/cib.3.3.11457] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 02/10/2010] [Indexed: 01/14/2023] Open
Abstract
Insulin triggers glucose uptake into muscle and adipose tissue by stimulating the translocation of the glucose transporter glut4 from intracellular vesicles to the plasma membrane (pm). insulin leads to a rapid increase in glut4 at the pm from approximately 5% to 40-50%. this effect is time and dose-dependent, reaching a new steady state after 30 min of insulin stimulation. previous kinetic analyses in adipocytes has revealed that this is regulated by two mechanisms-increasing the amount of glut4 in the endosomal recycling system and increasing the exocytosis rate constant. fazakerley et al.1 focuses on GLUT4 kinetics in the L6 skeletal muscle cell line. Despite displaying a similar redistribution of GLUT4 to the cell surface with insulin to that seen in adipocytes, the mechanism for this effect in L6 cells was completely different. Insulin had a modest effect to increase the amount of GLUT4 in the recycling system with the dominant effect being on reduction of the endocytosis rate constant. Similar findings were observed with AMPK agonists. These studies indicate that different cell types are capable of achieving the same cell biological endpoint but using completely distinct mechanisms.
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23
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Brewer PD, Romenskaia I, Kanow MA, Mastick CC. Loss of AS160 Akt substrate causes Glut4 protein to accumulate in compartments that are primed for fusion in basal adipocytes. J Biol Chem 2011; 286:26287-97. [PMID: 21613213 DOI: 10.1074/jbc.m111.253880] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Akt substrate AS160 (TCB1D4) regulates Glut4 exocytosis; shRNA knockdown of AS160 increases surface Glut4 in basal adipocytes. AS160 knockdown is only partially insulin-mimetic; insulin further stimulates Glut4 translocation in these cells. Insulin regulates translocation as follows: 1) by releasing Glut4 from retention in a slowly cycling/noncycling storage pool, increasing the actively cycling Glut4 pool, and 2) by increasing the intrinsic rate constant for exocytosis of the actively cycling pool (k(ex)). Kinetic studies were performed in 3T3-L1 adipocytes to measure the effects of AS160 knockdown on the rate constants of exocytosis (k(ex)), endocytosis (k(en)), and release from retention into the cycling pool. AS160 knockdown released Glut4 into the actively cycling pool without affecting k(ex) or k(en). Insulin increased k(ex) in the knockdown cells, further increasing cell surface Glut4. Inhibition of phosphatidylinositol 3-kinase or Akt affected both k(ex) and release from retention in control cells but only k(ex) in AS160 knockdown cells. Glut4 vesicles accumulate in a primed pre-fusion pool in basal AS160 knockdown cells. Akt regulates the rate of exocytosis of the primed vesicles through an AS160-independent mechanism. Therefore, there is an additional Akt substrate that regulates the fusion of Glut4 vesicles that remain to be identified. Mathematical modeling was used to test the hypothesis that this substrate regulates vesicle priming (release from retention), whereas AS160 regulates the reverse step by stimulating GTP turnover of a Rab protein required for vesicle tethering/docking/fusion. Our analysis indicates that fusion of the primed vesicles with the plasma membrane is an additional non-Akt-dependent insulin-regulated step.
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Affiliation(s)
- Paul Duffield Brewer
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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24
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Habtemichael EN, Brewer PD, Romenskaia I, Mastick CC. Kinetic evidence that Glut4 follows different endocytic pathways than the receptors for transferrin and alpha2-macroglobulin. J Biol Chem 2011; 286:10115-25. [PMID: 21252237 DOI: 10.1074/jbc.m111.217935] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin regulates glucose uptake through effects on the trafficking of the glucose transporter Glut4. To investigate the degree of overlap between Glut4 and the general endocytic pathways, the kinetics of trafficking of Glut4 and the receptors for transferrin (Tf) and α(2)-macroglobulin (α-2-M; LRP-1) were compared using quantitative flow cytometric assays. Insulin increased the exocytic rate constant (k(ex)) for both Glut4 and Tf. However, the k(ex) of Glut4 was 5-15 times slower than Tf in both basal and insulin-stimulated cells. The endocytic rate constant (k(en)) of Glut4 was also five times slower than Tf. Insulin did not affect the k(en) of either protein. In basal cells, the k(en) for α-2-M/LRP-1 was similar to Glut4 but 5-fold slower than Tf. Insulin increased k(en) for α-2-M/LRP-1 by 30%. In contrast, the k(ex) for LRP-1 was five times faster than Glut4 in basal cells, and insulin did not increase this rate constant. Thus, although there is overlap in the protein machineries/compartments utilized, the differences in trafficking kinetics indicate that Glut4, the Tf receptor, and LRP-1 are differentially processed both within the cell and at the plasma membrane. It has been reported that insulin decreases the k(en) of Glut4 in adipocytes. However, the effect of exocytosis on the "internalization" assays was not considered. Because it is counterintuitive, the effect of exocytosis on these assays is often overlooked in endocytosis studies. Using mathematical modeling and simulation, we show that the reported decrease in Glut4 k(en) can be entirely accounted for by the well established increase in Glut4 k(ex).
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Affiliation(s)
- Estifanos N Habtemichael
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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25
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Stenkula KG, Lizunov VA, Cushman SW, Zimmerberg J. Insulin controls the spatial distribution of GLUT4 on the cell surface through regulation of its postfusion dispersal. Cell Metab 2010; 12:250-9. [PMID: 20816091 PMCID: PMC3427691 DOI: 10.1016/j.cmet.2010.08.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/19/2010] [Accepted: 06/07/2010] [Indexed: 01/06/2023]
Abstract
While the glucose transporter-4 (GLUT4) is fundamental to insulin-regulated glucose metabolism, its dynamic spatial organization in the plasma membrane (PM) is unclear. Here, using multicolor TIRF microscopy in transfected adipose cells, we demonstrate that insulin regulates not only the exocytosis of GLUT4 storage vesicles but also PM distribution of GLUT4 itself. In the basal state, domains (clusters) of GLUT4 molecules in PM are created by an exocytosis that retains GLUT4 at the fusion site. Surprisingly, when insulin induces a burst of GLUT4 exocytosis, it does not merely accelerate this basal exocytosis but rather stimulates approximately 60-fold another mode of exocytosis that disperses GLUT4 into PM. In contradistinction, internalization of most GLUT4, regardless of insulin, occurs from pre-existing clusters via the subsequent recruitment of clathrin. The data fit a new kinetic model that features multifunctional clusters as intermediates of exocytosis and endocytosis.
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Affiliation(s)
- Karin G Stenkula
- Experimental Diabetes, Metabolism, and Nutrition Section, Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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26
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Muretta JM, Mastick CC. How insulin regulates glucose transport in adipocytes. VITAMINS AND HORMONES 2009; 80:245-86. [PMID: 19251041 DOI: 10.1016/s0083-6729(08)00610-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Insulin stimulates glucose storage and metabolism by the tissues of the body, predominantly liver, muscle and fat. Storage in muscle and fat is controlled to a large extent by the rate of facilitative glucose transport across the plasma membrane of the muscle and fat cells. Insulin controls this transport. Exactly how remains debated. Work presented in this review focuses on the pathways responsible for the regulation of glucose transport by insulin. We present some historical work to show how the prevailing model for regulation of glucose transport by insulin was originally developed, then some more recent data challenging this model. We finish describing a unifying model for the control of glucose transport, and some very recent data illustrating potential molecular machinery underlying this regulation. This review is meant to give an overview of our current understanding of the regulation of glucose transport through the regulation of the trafficking of Glut4, highlighting important questions that remain to be answered. A more detailed treatment of specific aspects of this pathway can be found in several excellent recent reviews (Brozinick et al., 2007 Hou and Pessin, 2007; Huang and Czech, 2007;Larance et al., 2008 Sakamoto and Holman, 2008; Watson and Pessin, 2007; Zaid et al., 2008)One of the main objectives of this review is to discuss the results of the experiments measuring the kinetics of Glut4 movement between subcellular compartments in the context of our emerging model of the Glut4 trafficking pathway.
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Affiliation(s)
- Joseph M Muretta
- Department of Biochemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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27
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Compartmentalization and regulation of insulin signaling to GLUT4 by the cytoskeleton. VITAMINS AND HORMONES 2009; 80:193-215. [PMID: 19251039 DOI: 10.1016/s0083-6729(08)00608-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
One of the early events in the development of Type 2 diabetes appears to be an inhibition of insulin-mediated GLUT4 redistribution to the cell surface in tissues that express GLUT4. Understanding this process, and how it begins to breakdown in the development of insulin resistance is quite important as we face treatment and prevention of metabolic diseases. Over the past few years, and increasing number of laboratories have produced compelling data to demonstrate a role for both the actin and microtubule networks in the regulation of insulin-mediated GLUT4 redistribution to the cell surface. In this review, we explore this process from insulin-signal transduction to fusion of GLUT4 membrane vesicles, focusing on studies that have implicated a role for the cytoskeleton. We see from this body of work that both the actin network and the microtubule cytoskeleton play roles as targets of insulin action and effectors of insulin signaling leading to changes in GLUT4 redistribution to the cell surface and insulin-mediated glucose uptake.
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28
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Birtwistle MR, Kholodenko BN. Endocytosis and signalling: a meeting with mathematics. Mol Oncol 2009; 3:308-20. [PMID: 19596615 DOI: 10.1016/j.molonc.2009.05.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022] Open
Abstract
Although endocytosis has traditionally been understood as a signal attenuation mechanism, an emerging view considers endocytosis as an integral part of signal propagation and processing. On the short time scale, trafficking of endocytic vesicles contributes to signal propagation from the surface to distant targets, with bi-directional communication between signalling and trafficking. Mathematical modelling helps combine the mechanistic, molecular knowledge with rigorous analysis of the complex output dynamics of endocytosis in time and space. Simulations reveal novel roles for endocytosis, including the control of cell polarity, enhancing the spatial signal propagation, and controlling the signal magnitudes, kinetics, and synchronization with stimulus dynamics.
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Affiliation(s)
- Marc R Birtwistle
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland
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29
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Chew YH, Shia YL, Lee CT, Majid FAA, Chua LS, Sarmidi MR, Aziz RA. Modeling of glucose regulation and insulin-signaling pathways. Mol Cell Endocrinol 2009; 303:13-24. [PMID: 19428987 DOI: 10.1016/j.mce.2009.01.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 12/22/2008] [Accepted: 01/26/2009] [Indexed: 01/31/2023]
Abstract
A model of glucose regulation system was combined with a model of insulin-signaling pathways in this study. A feedback loop was added to link the transportation of glucose into cells (by GLUT4 in the insulin-signaling pathways) and the insulin-dependent glucose uptake in the glucose regulation model using the Michaelis-Menten kinetic model. A value of K(m) for GLUT4 was estimated using Genetic Algorithm. The estimated value was found to be 25.3 mM, which was in the range of K(m) values found experimentally from in vivo and in vitro human studies. Based on the results of this study, the combined model enables us to understand the overall dynamics of glucose at the systemic level, monitor the time profile of components in the insulin-signaling pathways at the cellular level and gives a good estimate of the K(m) value of glucose transportation by GLUT4. In conclusion, metabolic modeling such as displayed in this study provides a good predictive method to study the step-by-step reactions in an organism at different levels and should be used in combination with experimental approach to increase our understanding of metabolic disorders such as type 2 diabetes.
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Affiliation(s)
- Yin Hoon Chew
- Department of Bioprocess Engineering, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
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30
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Karlsson HK, Chibalin AV, Koistinen HA, Yang J, Koumanov F, Wallberg-Henriksson H, Zierath JR, Holman GD. Kinetics of GLUT4 trafficking in rat and human skeletal muscle. Diabetes 2009; 58:847-54. [PMID: 19188436 PMCID: PMC2661600 DOI: 10.2337/db08-1539] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE In skeletal muscle, insulin stimulates glucose transport activity three- to fourfold, and a large part of this stimulation is associated with a net translocation of GLUT4 from an intracellular compartment to the cell surface. We examined the extent to which insulin or the AMP-activated protein kinase activator AICAR can lead to a stimulation of the exocytosis limb of the GLUT4 translocation pathway and thereby account for the net increase in glucose transport activity. RESEARCH DESIGN AND METHODS Using a biotinylated photoaffinity label, we tagged endogenous GLUT4 and studied the kinetics of exocytosis of the tagged protein in rat and human skeletal muscle in response to insulin or AICAR. Isolated epitrochlearis muscles were obtained from male Wistar rats. Vastus lateralis skeletal muscle strips were prepared from open muscle biopsies obtained from six healthy men (age 39 +/- 11 years and BMI 25.8 +/- 0.8 kg/m2). RESULTS In rat epitrochlearis muscle, insulin exposure leads to a sixfold stimulation of the GLUT4 exocytosis rate (with basal and insulin-stimulated rate constants of 0.010 and 0.067 min(-1), respectively). In human vastus lateralis muscle, insulin stimulates GLUT4 translocation by a similar sixfold increase in the exocytosis rate constant (with basal and insulin-stimulated rate constants of 0.011 and 0.075 min(-1), respectively). In contrast, AICAR treatment does not markedly increase exocytosis in either rat or human muscle. CONCLUSIONS Insulin stimulation of the GLUT4 exocytosis rate constant is sufficient to account for most of the observed increase in glucose transport activity in rat and human muscle.
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Affiliation(s)
- Håkan K.R. Karlsson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Alexander V. Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Heikki A. Koistinen
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Department of Medicine, Division of Cardiology, Helsinki University Central Hospital, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Biomedicum 2U Helsinki, Helsinki, Finland
| | - Jing Yang
- Department of Biology and Biochemistry, University of Bath, Bath, U.K
| | | | | | - Juleen R. Zierath
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Geoffrey D. Holman
- Department of Biology and Biochemistry, University of Bath, Bath, U.K
- Corresponding author: Geoffrey D. Holman,
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31
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Lalioti VS, Vergarajauregui S, Tsuchiya Y, Hernandez-Tiedra S, Sandoval IV. Daxx functions as a scaffold of a protein assembly constituted by GLUT4, JNK1 and KIF5B. J Cell Physiol 2009; 218:416-26. [DOI: 10.1002/jcp.21614] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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32
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Rubin BR, Bogan JS. Intracellular retention and insulin-stimulated mobilization of GLUT4 glucose transporters. VITAMINS AND HORMONES 2009; 80:155-92. [PMID: 19251038 DOI: 10.1016/s0083-6729(08)00607-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
GLUT4 glucose transporters are expressed nearly exclusively in adipose and muscle cells, where they cycle to and from the plasma membrane. In cells not stimulated with insulin, GLUT4 is targeted to specialized GLUT4 storage vesicles (GSVs), which sequester it away from the cell surface. Insulin acts within minutes to mobilize these vesicles, translocating GLUT4 to the plasma membrane to enhance glucose uptake. The mechanisms controlling GSV sequestration and mobilization are poorly understood. An insulin-regulated aminopeptidase that cotraffics with GLUT4, IRAP, is required for basal GSV retention and insulin-stimulated mobilization. TUG and Ubc9 bind GLUT4, and likely retain GSVs within unstimulated cells. These proteins may be components of a retention receptor, which sequesters GLUT4 and IRAP away from recycling vesicles. Insulin may then act on this protein complex to liberate GLUT4 and IRAP, discharging GSVs into a recycling pathway for fusion at the cell surface. How GSVs are anchored intracellularly, and how insulin mobilizes these vesicles, are the important topics for ongoing research. Regulation of GLUT4 trafficking is tissue-specific, perhaps in part because the formation of GSVs requires cell type-specific expression of sortilin. Proteins controlling GSV retention and mobilization can then be more widely expressed. Indeed, GLUT4 likely participates in a general mechanism by which the cell surface delivery of various membrane proteins can be controlled by extracellular stimuli. Finally, it is not known if defects in the formation or intracellular retention of GSVs contribute to human insulin resistance, or play a role in the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Bradley R Rubin
- Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06520-8020, USA
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33
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Abstract
Many integral membrane proteins synthesized in the endoplasmic reticulum ultimately arrive at the cell surface to contact the cell environment. During transit through the Golgi and trans-Golgi network, proteins acquire post-translational modifications that can be used to track the appearance of such modified proteins at the cell surface. Cellular proteins can be treated with enzymes--e.g., sialidase or protease--or antibodies, or biotinylated to identify molecules that have reached the cell surface. Some proteins first enter the endocytic pathway before appearing at the cell surface; this is detected by treating the cells at 4 degrees and 37 degrees C. Analysis of the number of sialic acids on proteins of cells treated at 4 degrees C identifies proteins resident at the cell surface, while cells treated at 37 degrees C internalize the sialidase, which can then act with proteins in the endocytic compartments.
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Affiliation(s)
- T E McGraw
- Weill Medical School of Cornell University, New York, New York, USA
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34
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Chen Y, Wang Y, Ji W, Xu P, Xu T. A pre-docking role for microtubules in insulin-stimulated glucose transporter 4 translocation. FEBS J 2008; 275:705-12. [PMID: 18190526 DOI: 10.1111/j.1742-4658.2007.06232.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Insulin stimulates glucose uptake by inducing translocation of glucose transporter 4 (GLUT4) from intracellular resides to the plasma membrane. How GLUT4 storage vesicles are translocated from the cellular interior to the plasma membrane remains to be elucidated. In the present study, intracellular transport of GLUT4 storage vesicles and the kinetics of their docking at the plasma membrane were comprehensively investigated at single vesicle level in control and microtubule-disrupted 3T3-L1 adipocytes by time-lapse total internal reflection fluorescence microscopy. It is demonstrated that microtubule disruption substantially inhibited insulin-stimulated GLUT4 translocation. Detailed analysis reveals that microtubule disruption blocked the recruitment of GLUT4 storage vesicles to underneath the plasma membrane and abolished the docking of them at the plasma membrane. These data suggest that transport of GLUT4 storage vesicles to the plasma membrane takes place along microtubules and that this transport is obligatory for insulin-stimulated GLUT4 translocation.
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Affiliation(s)
- Yu Chen
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
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35
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Muretta JM, Romenskaia I, Mastick CC. Insulin releases Glut4 from static storage compartments into cycling endosomes and increases the rate constant for Glut4 exocytosis. J Biol Chem 2007; 283:311-323. [PMID: 17967900 DOI: 10.1074/jbc.m705756200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In adipocytes, insulin triggers the redistribution of Glut4 from intracellular compartments to the plasma membrane. Two models have been proposed to explain the effect of insulin on Glut4 localization. In the first, termed dynamic exchange, Glut4 continually cycles between the plasma membrane and intracellular compartments in basal cells, and the major effect of insulin is through changes in the exocytic and endocytic rate constants, k(ex) and k(en). In the second model, termed static retention, Glut4 is packaged in specialized storage vesicles (GSVs) in basal cells and does not traffic through the plasma membrane or endosomes. Insulin triggers GSV exocytosis, increasing the amount of Glut4 in the actively cycling pool. Using a flow cytometry-based assay, we found that Glut4 is regulated by both static and dynamic retention mechanisms. In basal cells, 75-80% of the Glut4 is packaged in noncycling GSVs. Insulin increased the amount of Glut4 in the actively cycling pool 4-5-fold. Insulin also increased k(ex) in the cycling pool 3-fold. After insulin withdrawal, Glut4 is rapidly cleared from the plasma membrane (t((1/2)) of 20 min) by rapid adjustments in k(ex) and k(en) and recycled into static compartments. Complete recovery of the static pool required more than 3 h, however. We conclude that in fully differentiated confluent adipocytes, both the dynamic and static retention mechanisms are important for the regulation of plasma membrane Glut4 content. However, cell culture conditions affect Glut4 trafficking. For example, replating after differentiation inhibited the static retention of Glut4, which may explain differences in previous reports.
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Affiliation(s)
- Joseph M Muretta
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557
| | - Irina Romenskaia
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557
| | - Cynthia Corley Mastick
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557.
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36
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Xu YK, Xu KD, Li JY, Feng LQ, Lang D, Zheng XX. Bi-directional transport of GLUT4 vesicles near the plasma membrane of primary rat adipocytes. Biochem Biophys Res Commun 2007; 359:121-8. [PMID: 17532293 DOI: 10.1016/j.bbrc.2007.05.075] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 05/11/2007] [Indexed: 01/05/2023]
Abstract
Insulin stimulates glucose uptake into adipocytes by mobilizing intracellular membrane vesicles containing GLUT4 proteins to the plasma membrane. Here we applied time-lapse total internal reflection fluorescence microscopy to study moving parameters and characters of exogenously expressed GLUT4 vesicles in basal, insulin and nocodazole treated primary rat adipocytes. Our results showed that microtubules were essential for long-range transport of GLUT4 vesicles but not obligatory for GLUT4 distribution in rat adipocytes. Insulin reduced the mobility of the vesicles, made them tethered/docked to the PM and finally had constitutive exocytosis. Moreover, long-range bi-directional movements of GLUT4 vesicles were visualized for the first time by TIRFM. It is likely that there are interactions between insulin signaling and microtubules, to regulating GLUT4 translocation in rat adipocytes.
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Affiliation(s)
- Ying-Ke Xu
- Key Laboratory for Biomedical Engineering of Ministry of China, Department of Biomedical Engineering, Zhejiang University, Zhejiang 310027, PR China
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37
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Kevorkova O, Ethier-Chiasson M, Lafond J. Differential Expression of Glucose Transporters in Rabbit Placenta: Effect of Hypercholesterolemia in Dams1. Biol Reprod 2007; 76:487-95. [PMID: 17135483 DOI: 10.1095/biolreprod.106.055285] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Low birth weight is observed in rabbit offspring when maternal hypercholesterolemia is induced during gestation, but the related etiology is still unknown. Glucose is one of the most important substances during fetal development, and defect in glucose supply to fetus was related to pathophysiological mechanisms in intrauterine growth restriction. Thus, the aim of this work was to evaluate the impact of maternal hypercholesterolemia during rabbit gestation on the glucose metabolism and the routing of glucose transporters (SLC2 and SLC5 [previously known as GLUT and SGLT]) in placenta. In this study, maternal and offspring serum levels of glucose and insulin were evaluated for control and hypercholesterolemic groups, and the mRNA and protein expressions of placental SLCs were quantified by real-time RT-PCR and Western immunoblot, respectively. Our data demonstrate that maternal hypercholesterolemia during gestation: 1) induces offspring hypoglycemia; 2) does not modify the genetic and protein expressions of SLC2A1 and SLC2A4 (previously GLUT1 and GLUT4) in total placental extract; 3) downregulates the placental SLC5A1 (previously SGLT1) protein expression without affecting its mRNA levels; 4) impairs the translocation of SLC2A1 but not SLC2A4 from cytoplasmatic pool to the cell membrane surface. Then we assume that reduction of offspring birth weight in presence of maternal hypercholesterolemia may be related to the offspring's hypoglycemia and the reduction of the cell surface expression of placental SLC2A1.
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Affiliation(s)
- Olha Kevorkova
- Laboratoire de Physiologie Materno-Foetale, and Centre de Recherche BioMed, Université du Québec à Montréal, Montréal, Québec, Canada H3C 3P8
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38
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Bai L, Wang Y, Fan J, Chen Y, Ji W, Qu A, Xu P, James DE, Xu T. Dissecting multiple steps of GLUT4 trafficking and identifying the sites of insulin action. Cell Metab 2007; 5:47-57. [PMID: 17189206 DOI: 10.1016/j.cmet.2006.11.013] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 10/17/2006] [Accepted: 11/17/2006] [Indexed: 01/24/2023]
Abstract
Insulin-stimulated GLUT4 translocation is central to glucose homeostasis. Functional assays to distinguish individual steps in the GLUT4 translocation process are lacking, thus limiting progress toward elucidation of the underlying molecular mechanism. Here we have developed a robust method, which relies on dynamic tracking of single GLUT4 storage vesicles (GSVs) in real time, for dissecting and systematically analyzing the docking, priming, and fusion steps of GSVs with the cell surface in vivo. Using this method, we have shown that the preparation of GSVs for fusion competence after docking at the surface is a key step regulated by insulin, whereas the docking step is regulated by PI3K and its downstream effector, the Rab GAP AS160. These data show that Akt-dependent phosphorylation of AS160 is not the major regulated step in GLUT4 trafficking, implicating alternative Akt substrates or alternative signaling pathways downstream of GSV docking at the cell surface as the major regulatory node.
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Affiliation(s)
- Li Bai
- Joint Laboratory of Institute of Biophysics and Huazhong University of Science and Technology, National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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39
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Eyster CA, Duggins QS, Gorbsky GJ, Olson AL. Microtubule network is required for insulin signaling through activation of Akt/protein kinase B: evidence that insulin stimulates vesicle docking/fusion but not intracellular mobility. J Biol Chem 2006; 281:39719-27. [PMID: 17068336 DOI: 10.1074/jbc.m607101200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The microtubule network has been shown to be required for insulin-dependent GLUT4 redistribution; however, the precise molecular function has not been elucidated. In this article, we used fluorescence recovery after photobleaching (FRAP) to evaluate the role of microtubules in intracellular GLUT4 vesicle mobility. A comparison of the rate of fluorescence recovery (t((1/2))), and the maximum fluorescence recovered (F(max)) was made between basal and insulin-treated cells with or without nocodazole treatment to disrupt microtubules. We found that intracellular mobility of fluorescently tagged GLUT4 (HA-GLUT4-GFP) was high in basal cells. Mobility was not increased by insulin treatment. Basal mobility was dependent upon an intact microtubule network. Using a constitutively active Akt to signal GLUT4 redistribution, we found that microtubule-based GLUT4 vesicle mobility was not obligatory for GLUT4 plasma membrane insertion. Our findings suggest that microtubules organize the insulin-signaling complex and provide a surface for basal mobility of GLUT4 vesicles. Our data do not support an obligatory requirement for long range microtubule-based movement of GLUT4 vesicles for insulin-mediated GLUT4 redistribution to the cell surface. Taken together, these findings suggest a model in which insulin signaling targets membrane docking and/or fusion rather than GLUT4 trafficking to the cell surface.
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Affiliation(s)
- Craig A Eyster
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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40
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Liu G, Hou JC, Watson RT, Pessin JE. Initial entry of IRAP into the insulin-responsive storage compartment occurs prior to basal or insulin-stimulated plasma membrane recycling. Am J Physiol Endocrinol Metab 2005; 289:E746-52. [PMID: 15928022 DOI: 10.1152/ajpendo.00175.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To examine the acquisition of insulin sensitivity after the initial biosynthesis of the insulin-responsive aminopeptidase (IRAP), 3T3-L1 adipocytes were transfected with an enhanced green fluorescent protein-IRAP (EGFP-IRAP) fusion protein. In the absence of insulin, IRAP was rapidly localized (1-3 h) to secretory membranes and retained in these intracellular membrane compartments with little accumulation at the plasma membrane. However, insulin was unable to induce translocation to the plasma membrane until 6-9 h after biosynthesis. This was in marked contrast to another type II membrane protein (syntaxin 3) that rapidly defaulted to the plasma membrane 3 h after expression. In parallel with the time-dependent acquisition of insulin responsiveness, the newly synthesized IRAP protein converted from a brefeldin A-sensitive to a brefeldin A-insensitive state. The initial trafficking of IRAP to the insulin-responsive compartment was independent of plasma membrane endocytosis, as expression of a dominant-interfering dynamin mutant (Dyn/K44A) inhibited transferrin receptor endocytosis but had no effect on the insulin-stimulated translocation of the newly synthesized IRAP protein.
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Affiliation(s)
- Gang Liu
- Dept. of Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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41
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Lizunov VA, Matsumoto H, Zimmerberg J, Cushman SW, Frolov VA. Insulin stimulates the halting, tethering, and fusion of mobile GLUT4 vesicles in rat adipose cells. ACTA ACUST UNITED AC 2005; 169:481-9. [PMID: 15866888 PMCID: PMC2171949 DOI: 10.1083/jcb.200412069] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucose transport in adipose cells is regulated by changing the distribution of glucose transporter 4 (GLUT4) between the cell interior and the plasma membrane (PM). Insulin shifts this distribution by augmenting the rate of exocytosis of specialized GLUT4 vesicles. We applied time-lapse total internal reflection fluorescence microscopy to dissect intermediates of this GLUT4 translocation in rat adipose cells in primary culture. Without insulin, GLUT4 vesicles rapidly moved along a microtubule network covering the entire PM, periodically stopping, most often just briefly, by loosely tethering to the PM. Insulin halted this traffic by tightly tethering vesicles to the PM where they formed clusters and slowly fused to the PM. This slow release of GLUT4 determined the overall increase of the PM GLUT4. Thus, insulin initially recruits GLUT4 sequestered in mobile vesicles near the PM. It is likely that the primary mechanism of insulin action in GLUT4 translocation is to stimulate tethering and fusion of trafficking vesicles to specific fusion sites in the PM.
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Affiliation(s)
- Vladimir A Lizunov
- Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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42
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Eyster CA, Duggins QS, Olson AL. Expression of Constitutively Active Akt/Protein Kinase B Signals GLUT4 Translocation in the Absence of an Intact Actin Cytoskeleton. J Biol Chem 2005; 280:17978-85. [PMID: 15738003 DOI: 10.1074/jbc.m409806200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The actin cytoskeleton has been shown to be required for insulin-dependent GLUT4 translocation; however, the role that the actin network plays is unknown. Actin may play a role in formation of an active signaling complex, or actin may be required for movement of vesicles to the plasma membrane surface. To distinguish between these possibilities, we examined the ability of myr-Akt, a constitutively active form of Akt that signals GLUT4 translocation to the plasma membrane in the absence of insulin, to signal translocation of an HA-GLUT4-GFP reporter protein in the presence or absence of an intact cytoskeleton in 3T3-L1 adipocytes. Expression of myr-Akt signaled the redistribution of the GLUT4 reporter protein to the cell surface in the absence or presence of 10 microm latrunculin B, a concentration sufficient to completely inhibit insulin-dependent redistribution of the GLUT4 reporter to the cell surface. These data suggest that the actin network plays a primary role in organization of the insulin-signaling complex. To further support this conclusion, we measured the activation of known signaling proteins using a saturating concentration of insulin in cells pretreated without or with 10 microm latrunculin B. We found that latrunculin treatment did not affect insulin-dependent tyrosine phosphorylation of the insulin receptor beta-subunit and IRS-1 but completely inhibited activation of Akt/PKB enzymatic activity. Phosphorylation of Akt/PKB at Ser-473 and Thr-308 was inhibited by latrunculin B treatment, indicating that the defect in signaling lies prior to Akt/PKB activation. In summary, our data support the hypothesis that the actin network plays a role in organization of the insulin-signaling complex but is not required for vesicle trafficking and/or fusion.
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Affiliation(s)
- Craig A Eyster
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA
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43
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van Dam EM, Govers R, James DE. Akt Activation Is Required at a Late Stage of Insulin-Induced GLUT4 Translocation to the Plasma Membrane. Mol Endocrinol 2005; 19:1067-77. [PMID: 15650020 DOI: 10.1210/me.2004-0413] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
AbstractInsulin stimulates the translocation of glucose transporter GLUT4 from intracellular vesicles to the plasma membrane (PM). This involves multiple steps as well as multiple intracellular compartments. The Ser/Thr kinase Akt has been implicated in this process, but its precise role is ill defined. To begin to dissect the role of Akt in these different steps, we employed a low-temperature block. Upon incubation of 3T3-L1 adipocytes at 19 C, GLUT4 accumulated in small peripheral vesicles with a slight increase in PM labeling concomitant with reduced trans-Golgi network labeling. Although insulin-dependent translocation of GLUT4 to the PM was impaired at 19 C, we still observed movement of vesicles toward the surface. Strikingly, insulin-stimulated Akt activity, but not phosphatidylinositol 3 kinase activity, was blocked at 19 C. Consistent with a multistep process in GLUT4 trafficking, insulin-stimulated GLUT4 translocation could be primed by treating cells with insulin at 19 C, whereas this was not the case for Akt activation. These data implicate two insulin-regulated steps in GLUT4 translocation: 1) redistribution of GLUT4 vesicles toward the cell cortex—this process is Akt-independent and is not blocked at 19 C; and 2) docking and/or fusion of GLUT4 vesicles with the PM—this process may be the major Akt-dependent step in the insulin regulation of glucose transport.
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Affiliation(s)
- Ellen M van Dam
- Garvan Institute of Medical Research, St. Vincent's Hospital, 384 Victoria Street, Darlinghurst, 2010 New South Wales, Australia
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44
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Bazuine M, Carlotti F, Rabelink MJWE, Vellinga J, Hoeben RC, Maassen JA. The p38 mitogen-activated protein kinase inhibitor SB203580 reduces glucose turnover by the glucose transporter-4 of 3T3-L1 adipocytes in the insulin-stimulated state. Endocrinology 2005; 146:1818-24. [PMID: 15665038 DOI: 10.1210/en.2004-1347] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Insulin induces a profound increase in glucose uptake in 3T3-L1 adipocytes through the activity of the glucose transporter-4 (GLUT4). Apart from GLUT4 translocation toward the plasma membrane, there is also an insulin-induced p38 MAPK-dependent step involved in the regulation of glucose uptake. Consequently, treatment with the p38 MAPK inhibitor SB203580 reduces insulin-induced glucose uptake by approximately 30%. Pretreatment with SB203580 does not alter the apparent K(m) of GLUT4-mediated glucose uptake but reduces the maximum velocity by approximately 30%. Insulin-induced GLUT4 translocation and exposure of the transporter to the extracellular environment was not altered by pretreatment with SB203580, as evidenced by a lack of effect of the inhibitor on the amount of GLUT4 present in the plasma membrane, as assessed by subcellular fractionation, the amount of GLUT4 that is able to undergo biotinylation on intact adipocytes and the level of extracellular exposure of an ectopically expressed GLUT-green fluorescence protein construct with a hemagglutinin tag in its first extracellular loop. In contrast, labeling of GLUT4 after insulin stimulation by a membrane-impermeable, mannose moiety-containing, photoaffinity-labeling agent [2-N-4(1-azido-2,2,2-trifluoroethyl)benzoyl-1,3-bis(d-mannose-4-yloxy)-2-propylamine] that binds to the extracellular glucose acceptor domain was markedly reduced by SB203580, although photolabeling with this compound in the absence of insulin was unaffected by SB203580. These data suggest that SB203580 affects glucose turnover by the insulin-responsive GLUT4 transporter in 3T3-L1 adipocytes.
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Affiliation(s)
- Merlijn Bazuine
- Signal Transduction Laboratory, Department of Molecular Cell Biology, Leiden University Medical Center, Wassenaarseweg 72, P.O. Box 9503, 2333 AL Leiden, The Netherlands
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45
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Yang J, Holman GD. Insulin and Contraction Stimulate Exocytosis, but Increased AMP-activated Protein Kinase Activity Resulting from Oxidative Metabolism Stress Slows Endocytosis of GLUT4 in Cardiomyocytes. J Biol Chem 2005; 280:4070-8. [PMID: 15557332 DOI: 10.1074/jbc.m410213200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Stimulations of glucose transport produced by insulin action, contraction, or through a change in cell energy status are mediated by separate signaling pathways. These are the wortmannin-sensitive phosphatidylinositol 3-kinase pathway leading to the intermediate Akt and the wortmannin-insensitive AMP-activated protein kinase (AMPK) pathway. Electrical stimulation of cardiomyocytes produced a rapid, insulin-like, wortmannin-sensitive stimulation of glucose transport activity, but this occurred without extensive activation of Akt. Although AMPK phosphorylation was increased by contraction, this response was not wortmannin-inhibitable and consequently did not correlate with the wortmannin sensitivity of the transport stimulation. Oxidative metabolism stress due to hypoxia or treatment with oligomycin led to increased AMPK activity with a corresponding increase in glucose transport activity. We show here that these separate signaling pathways converge on GLUT4 trafficking at separate steps. The rate of exocytosis of GLUT4 was rapidly stimulated by insulin, but insulin treatment did not alter the endocytosis rate. Like insulin stimulation, electrical stimulation of contraction led to a stimulation of GLUT4 exocytosis without any marked change in endocytosis. By contrast, after oxidative metabolism stress, no stimulation of GLUT4 exocytosis occurred; instead, this treatment led to a reduction in GLUT4 endocytosis.
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Affiliation(s)
- Jing Yang
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom
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46
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Bazuine M, van den Broek PJA, Maassen JA. Genistein directly inhibits GLUT4-mediated glucose uptake in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2005; 326:511-4. [PMID: 15582607 DOI: 10.1016/j.bbrc.2004.11.055] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2004] [Indexed: 11/29/2022]
Abstract
The isoflavone-derivative genistein is commonly applied as an inhibitor of tyrosine kinases. In this report we analyze the effect of genistein on insulin-stimulated glucose uptake in 3T3-L1 adipocytes. In these cells insulin-induced glucose uptake is primarily mediated by the GLUT4 glucose transporter. We observed that pre-treatment with genistein did not affect insulin-induced tyrosine kinase activity of the insulin receptor or activation of protein kinase B. On the other hand, genistein acted as a direct inhibitor of insulin-induced glucose uptake in 3T3-L1 adipocytes with an IC(50) of 20 microM. We conclude that apart from acting as a general tyrosine kinase inhibitor, genistein also affects the function of other proteins such as the GLUT4 transporter. These data suggest that caution must be applied when interpreting data on the involvement of tyrosine kinase activity in glucose uptake in 3T3-L1 adipocytes.
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Affiliation(s)
- Merlijn Bazuine
- Department of Molecular Cell Biology, Leiden University Medical Center, P.O. Box 9503, 2333 AL, Leiden, The Netherlands
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47
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Sögård P, Harlén M, Svensson LT, Zierath JR, Nilsson P. Integration of mathematical and experimental approaches to resolve insulin signalling. ACTA PHYSIOLOGICA SCANDINAVICA 2005; 183:125-6. [PMID: 15654926 DOI: 10.1111/j.1365-201x.2004.01409.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
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48
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Wertheim N, Cai Z, McGraw TE. The Transcription Factor CCAAT/Enhancer-binding Protein α Is Required for the Intracellular Retention of GLUT4. J Biol Chem 2004; 279:41468-76. [PMID: 15277525 DOI: 10.1074/jbc.m405088200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin modulates glucose uptake into adipocytes by regulating the trafficking of the GLUT4 glucose transporter. GLUT4 is mostly excluded from the surface of unstimulated cells because it is much more slowly exocytosed than it is endocytosed. GLUT4 traffics through an adipocyte-specific, specialized endosomal recycling pathway that only partially overlaps with compartments of the general endosomal recycling pathway. Insulin stimulates GLUT4 exocytosis and partially inhibits its endocytosis, resulting in GLUT4 redistribution to the cell surface. Insulin does not stimulate glucose uptake into adipocytes lacking the CCAAT/enhancer-binding protein alpha (C/EBPalpha) transcription factor. Here we show that these adipocytes do not properly traffic GLUT4. In these adipocytes, GLUT4 was rapidly exocytosed in basal conditions, resulting in an accumulation of GLUT4 on the plasma membrane. Although the kinetics of GLUT4 trafficking were altered, GLUT4 was still targeted to specialized intracellular compartments in adipocytes lacking C/EBPalpha, demonstrating an uncoupling of the targeting of GLUT4 to a specialized, adipocyte-specific insulin-regulated pathway from the regulation of the movement of GLUT4 through this pathway. Re-expression of C/EBPalpha in adipocytes lacking C/EBPalpha restored normal GLUT4 trafficking. We propose that C/EBPalpha controls the expression of the proteins that determine the basal, slow exocytosis of GLUT4, but not the proteins required to make the adipocyte-specific compartments through which GLUT4 traffics. Furthermore, these data support a model in which insulin stimulates GLUT4 exocytosis by releasing an inhibitor of GLUT4 movement to the cell surface, and it is this clamp on basal exocytosis that is missing in adipocytes lacking C/EBPalpha.
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Affiliation(s)
- Nadine Wertheim
- Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10021, USA
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Coster ACF, Govers R, James DE. Insulin Stimulates the Entry of GLUT4 into the Endosomal Recycling Pathway by a Quantal Mechanism. Traffic 2004; 5:763-71. [PMID: 15355512 DOI: 10.1111/j.1600-0854.2004.00218.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The insulin-sensitive glucose transporter GLUT4 mediates the uptake of glucose into adipocytes and muscle cells. In this study we have used a novel 96-well plate fluorescence assay to study the kinetics of GLUT4 trafficking in 3T3-L1 adipocytes. We have found evidence for a graded release mechanism whereby GLUT4 is released into the plasma membrane recycling system in a nonkinetic manner as follows: the kinetics of appearance of GLUT4 at the plasma membrane is independent of the insulin concentration; a large proportion of GLUT4 molecules do not participate in plasma membrane recycling in the absence of insulin; and with increasing insulin there is an incremental increase in the total number of GLUT4 molecules participating in the recycling pathway rather than simply an increased rate of recycling. We propose a model whereby GLUT4 is stored in a compartment that is disengaged from the plasma membrane recycling system in the basal state. In response to insulin, GLUT4 is quantally released from this compartment in a pulsatile manner, leaving some sequestered from the recycling pathway even in conditions of excess insulin. Once disengaged from this location we suggest that in the continuous presence of insulin this quanta of GLUT4 continuously recycles to the plasma membrane, possibly via non-endosomal carriers that are formed at the perinuclear region.
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Affiliation(s)
- Adelle C F Coster
- School of Mathematics, University of New South Wales, Sydney 2052, Australia.
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Zeigerer A, McBrayer MK, McGraw TE. Insulin stimulation of GLUT4 exocytosis, but not its inhibition of endocytosis, is dependent on RabGAP AS160. Mol Biol Cell 2004; 15:4406-15. [PMID: 15254270 PMCID: PMC519136 DOI: 10.1091/mbc.e04-04-0333] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Insulin maintains whole body blood glucose homeostasis, in part, by regulating the amount of the GLUT4 glucose transporter on the cell surface of fat and muscle cells. Insulin induces the redistribution of GLUT4 from intracellular compartments to the plasma membrane, by stimulating a large increase in exocytosis and a smaller inhibition of endocytosis. A considerable amount is known about the molecular events of insulin signaling and the complex itinerary of GLUT4 trafficking, but less is known about how insulin signaling is transmitted to GLUT4 trafficking. Here, we show that the AS160 RabGAP, a substrate of Akt, is required for insulin stimulation of GLUT4 exocytosis. A dominant-inhibitory mutant of AS160 blocks insulin stimulation of exocytosis at a step before the fusion of GLUT4-containing vesicles with the plasma membrane. This mutant, however, does not block insulin-induced inhibition of GLUT4 endocytosis. These data support a model in which insulin signaling to the exocytosis machinery (AS160 dependent) is distinct from its signaling to the internalization machinery (AS160 independent).
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Affiliation(s)
- Anja Zeigerer
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021, USA
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