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Geiser A, Currie S, Al-Hasani H, Chadt A, McConnell G, Gould GW. A novel 3D imaging approach for quantification of GLUT4 levels across the intact myocardium. J Cell Sci 2024; 137:jcs262146. [PMID: 38958032 DOI: 10.1242/jcs.262146] [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: 03/26/2024] [Accepted: 06/24/2024] [Indexed: 07/04/2024] Open
Abstract
Cellular heterogeneity is a well-accepted feature of tissues, and both transcriptional and metabolic diversity have been revealed by numerous approaches, including optical imaging. However, the high magnification objective lenses needed for high-resolution imaging provides information from only small layers of tissue, which can result in poor cell statistics. There is therefore an unmet need for an imaging modality that can provide detailed molecular and cellular insight within intact tissue samples in 3D. Using GFP-tagged GLUT4 as proof of concept, we present here a novel optical mesoscopy approach that allows precise measurement of the spatial location of GLUT4 within specific anatomical structures across the myocardium in ultrathick sections (5 mm×5 mm×3 mm) of intact mouse heart. We reveal distinct GLUT4 distribution patterns across cardiac walls and highlight specific changes in GLUT4 expression levels in response to high fat diet-feeding, and we identify sex-dependent differences in expression patterns. This method is applicable to any target that can be labelled for light microscopy, and to other complex tissues when organ structure needs to be considered simultaneously with cellular detail.
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Affiliation(s)
- Angéline Geiser
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Susan Currie
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Hadi Al-Hasani
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz-Center for Diabetes Research at the Heinrich Heine University, Medical faculty, Düsseldorf, Germany
- German Center for Diabetes Research, Partner Düsseldorf, München-Neuherberg, Germany
| | - Alexandra Chadt
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz-Center for Diabetes Research at the Heinrich Heine University, Medical faculty, Düsseldorf, Germany
- German Center for Diabetes Research, Partner Düsseldorf, München-Neuherberg, Germany
| | - Gail McConnell
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Gwyn W Gould
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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2
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Tudurachi BS, Anghel L, Tudurachi A, Sascău RA, Zanfirescu RL, Stătescu C. Unraveling the Cardiac Matrix: From Diabetes to Heart Failure, Exploring Pathways and Potential Medications. Biomedicines 2024; 12:1314. [PMID: 38927520 PMCID: PMC11201699 DOI: 10.3390/biomedicines12061314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/08/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
Myocardial infarction (MI) often leads to heart failure (HF) through acute or chronic maladaptive remodeling processes. This establishes coronary artery disease (CAD) and HF as significant contributors to cardiovascular illness and death. Therefore, treatment strategies for patients with CAD primarily focus on preventing MI and lessening the impact of HF after an MI event. Myocardial fibrosis, characterized by abnormal extracellular matrix (ECM) deposition, is central to cardiac remodeling. Understanding these processes is key to identifying new treatment targets. Recent studies highlight SGLT2 inhibitors (SGLT2i) and GLP-1 receptor agonists (GLP1-RAs) as favorable options in managing type 2 diabetes due to their low hypoglycemic risk and cardiovascular benefits. This review explores inflammation's role in cardiac fibrosis and evaluates emerging anti-diabetic medications' effectiveness, such as SGLT2i, GLP1-RAs, and dipeptidyl peptidase-4 inhibitors (DPP4i), in preventing fibrosis in patients with diabetes post-acute MI. Recent studies were analyzed to identify effective medications in reducing fibrosis risk in these patients. By addressing these areas, we can advance our understanding of the potential benefits of anti-diabetic medications in reducing cardiac fibrosis post-MI and improve patient outcomes in individuals with diabetes at risk of HF.
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Affiliation(s)
- Bogdan-Sorin Tudurachi
- Internal Medicine Department, “Grigore T. Popa” University of Medicine and Pharmacy, 700503 Iasi, Romania; (B.-S.T.); (R.A.S.); (C.S.)
- Cardiology Department, Cardiovascular Diseases Institute “Prof. Dr. George I. M. Georgescu”, 700503 Iasi, Romania; (A.T.); (R.-L.Z.)
| | - Larisa Anghel
- Internal Medicine Department, “Grigore T. Popa” University of Medicine and Pharmacy, 700503 Iasi, Romania; (B.-S.T.); (R.A.S.); (C.S.)
- Cardiology Department, Cardiovascular Diseases Institute “Prof. Dr. George I. M. Georgescu”, 700503 Iasi, Romania; (A.T.); (R.-L.Z.)
| | - Andreea Tudurachi
- Cardiology Department, Cardiovascular Diseases Institute “Prof. Dr. George I. M. Georgescu”, 700503 Iasi, Romania; (A.T.); (R.-L.Z.)
| | - Radu Andy Sascău
- Internal Medicine Department, “Grigore T. Popa” University of Medicine and Pharmacy, 700503 Iasi, Romania; (B.-S.T.); (R.A.S.); (C.S.)
- Cardiology Department, Cardiovascular Diseases Institute “Prof. Dr. George I. M. Georgescu”, 700503 Iasi, Romania; (A.T.); (R.-L.Z.)
| | - Răzvan-Liviu Zanfirescu
- Cardiology Department, Cardiovascular Diseases Institute “Prof. Dr. George I. M. Georgescu”, 700503 Iasi, Romania; (A.T.); (R.-L.Z.)
- Physiology Department, “Grigore T. Popa” University of Medicine and Pharmacy, 700503 Iasi, Romania
| | - Cristian Stătescu
- Internal Medicine Department, “Grigore T. Popa” University of Medicine and Pharmacy, 700503 Iasi, Romania; (B.-S.T.); (R.A.S.); (C.S.)
- Cardiology Department, Cardiovascular Diseases Institute “Prof. Dr. George I. M. Georgescu”, 700503 Iasi, Romania; (A.T.); (R.-L.Z.)
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Barrett JS, Strauss JA, Chow LS, Shepherd SO, Wagenmakers AJM, Wang Y. GLUT4 localisation with the plasma membrane is unaffected by an increase in plasma free fatty acid availability. Lipids Health Dis 2024; 23:94. [PMID: 38566151 PMCID: PMC10986142 DOI: 10.1186/s12944-024-02079-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 03/13/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Insulin-stimulated glucose uptake into skeletal muscle occurs via translocation of GLUT4 from intracellular storage vesicles to the plasma membrane. Elevated free fatty acid (FFA) availability via a lipid infusion reduces glucose disposal, but this occurs in the absence of impaired proximal insulin signalling. Whether GLUT4 localisation to the plasma membrane is subsequently affected by elevated FFA availability is not known. METHODS Trained (n = 11) and sedentary (n = 10) individuals, matched for age, sex and body mass index, received either a 6 h lipid or glycerol infusion in the setting of a concurrent hyperinsulinaemic-euglycaemic clamp. Sequential muscle biopsies (0, 2 and 6 h) were analysed for GLUT4 membrane localisation and microvesicle size and distribution using immunofluorescence microscopy. RESULTS At baseline, trained individuals had more small GLUT4 spots at the plasma membrane, whereas sedentary individuals had larger GLUT4 spots. GLUT4 localisation with the plasma membrane increased at 2 h (P = 0.04) of the hyperinsulinemic-euglycemic clamp, and remained elevated until 6 h, with no differences between groups or infusion type. The number of GLUT4 spots was unchanged at 2 h of infusion. However, from 2 to 6 h there was a decrease in the number of small GLUT4 spots at the plasma membrane (P = 0.047), with no differences between groups or infusion type. CONCLUSION GLUT4 localisation with the plasma membrane increases during a hyperinsulinemic-euglycemic clamp, but this is not altered by elevated FFA availability. GLUT4 appears to disperse from small GLUT4 clusters located at the plasma membrane to support glucose uptake during a hyperinsulinaemic-euglycaemic clamp.
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Affiliation(s)
- J S Barrett
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool, L3 3AF, UK
| | - J A Strauss
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool, L3 3AF, UK
| | - L S Chow
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - S O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool, L3 3AF, UK.
| | - A J M Wagenmakers
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool, L3 3AF, UK
| | - Y Wang
- Discovery Sciences, AstraZeneca R&D, Cambridge Science Park, Milton Road, Cambridge, CB4 0WG, UK
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4
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García AP, Gaydou L, Pérez E, Barrantes FJ. Insulin resistance induced by long-term hyperinsulinemia abolishes the effects of acute insulin exposure on cell-surface nicotinic acetylcholine receptor levels and actin cytoskeleton morphology. Biochem Biophys Res Commun 2023; 685:149165. [PMID: 37922786 DOI: 10.1016/j.bbrc.2023.149165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023]
Abstract
Using CHO-K1/A5 cells, a clonal cell line that robustly expresses adult muscle-type nicotinic acetylcholine receptor (nAChR), we explored whether insulin resistance in these mammalian cells affects cell-surface expression of the nAChR, its endocytic internalization, and actin cytoskeleton integrity. Acute nanomolar insulin stimulation resulted in a slow increase in nAChR cell-surface levels, reaching maximum levels at ∼1 h. Long periods of insulin incubation caused CHO-K1/A5 cells to become insulin resistant, as previously observed with several other cell types. Furthermore, long-term insulin treatment abolished the effects of short-term insulin exposure on cell-surface nAChR levels, suggestive of a desensitization phenomenon. It also affected the kinetics of ligand-induced nAChR internalization. Since the integrity of the cortical actin cytoskeleton affects nAChR endocytosis, we also studied the effects of long-term insulin treatment on this meshwork. We found that it significantly affected the cortical actin morphology of CHO-K1/A5 cells and the response of the actin cytoskeleton to a subsequent short-term insulin stimulus. Overall, the present results show for the first time the effects of insulin signaling on cell-surface nAChR expression and actin cytoskeleton-associated internalization.
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Affiliation(s)
- Ana Paula García
- Laboratorio de Neurobiología Molecular, Instituto de Investigaciones Biomédicas (BIOMED) UCA-CONICET, Facultad de Ciencias Médicas, Universidad Católica de Argentina, Buenos Aires, Argentina; Instituto de Salud y Ambiente del Litoral (ISAL), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral-CONICET, Santa Fe, Argentina
| | - Luisa Gaydou
- Instituto de Salud y Ambiente del Litoral (ISAL), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral-CONICET, Santa Fe, Argentina; Departamento de Bioquímica Clínica y Cuantitativa, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Eugenia Pérez
- Laboratorio de Neurobiología Molecular, Instituto de Investigaciones Biomédicas (BIOMED) UCA-CONICET, Facultad de Ciencias Médicas, Universidad Católica de Argentina, Buenos Aires, Argentina
| | - Francisco J Barrantes
- Laboratorio de Neurobiología Molecular, Instituto de Investigaciones Biomédicas (BIOMED) UCA-CONICET, Facultad de Ciencias Médicas, Universidad Católica de Argentina, Buenos Aires, Argentina.
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Li J, Richmond B, Cluntun AA, Bia R, Walsh MA, Shaw K, Symons JD, Franklin S, Rutter J, Funai K, Shaw RM, Hong T. Cardiac gene therapy treats diabetic cardiomyopathy and lowers blood glucose. JCI Insight 2023; 8:e166713. [PMID: 37639557 PMCID: PMC10561727 DOI: 10.1172/jci.insight.166713] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 08/15/2023] [Indexed: 08/31/2023] Open
Abstract
Diabetic cardiomyopathy, an increasingly global epidemic and a major cause of heart failure with preserved ejection fraction (HFpEF), is associated with hyperglycemia, insulin resistance, and intracardiomyocyte calcium mishandling. Here we identify that, in db/db mice with type 2 diabetes-induced HFpEF, abnormal remodeling of cardiomyocyte transverse-tubule microdomains occurs with downregulation of the membrane scaffolding protein cardiac bridging integrator 1 (cBIN1). Transduction of cBIN1 by AAV9 gene therapy can restore transverse-tubule microdomains to normalize intracellular distribution of calcium-handling proteins and, surprisingly, glucose transporter 4 (GLUT4). Cardiac proteomics revealed that AAV9-cBIN1 normalized components of calcium handling and GLUT4 translocation machineries. Functional studies further identified that AAV9-cBIN1 normalized insulin-dependent glucose uptake in diabetic cardiomyocytes. Phenotypically, AAV9-cBIN1 rescued cardiac lusitropy, improved exercise intolerance, and ameliorated hyperglycemia in diabetic mice. Restoration of transverse-tubule microdomains can improve cardiac function in the setting of diabetic cardiomyopathy and can also improve systemic glycemic control.
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Affiliation(s)
- Jing Li
- Department of Pharmacology and Toxicology, College of Pharmacy
- Nora Eccles Harrison Cardiovascular Research and Training Institute
| | | | | | - Ryan Bia
- Nora Eccles Harrison Cardiovascular Research and Training Institute
| | - Maureen A. Walsh
- College of Health, Department of Nutrition and Integrative Physiology, Program in Molecular Medicine
| | - Kikuyo Shaw
- Department of Pharmacology and Toxicology, College of Pharmacy
| | - J. David Symons
- College of Health, Department of Nutrition and Integrative Physiology, Program in Molecular Medicine
- Diabetes & Metabolism Research Center, and
| | - Sarah Franklin
- Nora Eccles Harrison Cardiovascular Research and Training Institute
| | - Jared Rutter
- Department of Biochemistry
- College of Health, Department of Nutrition and Integrative Physiology, Program in Molecular Medicine
- Diabetes & Metabolism Research Center, and
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, USA
| | - Katsuhiko Funai
- College of Health, Department of Nutrition and Integrative Physiology, Program in Molecular Medicine
- Diabetes & Metabolism Research Center, and
| | - Robin M. Shaw
- Nora Eccles Harrison Cardiovascular Research and Training Institute
| | - TingTing Hong
- Department of Pharmacology and Toxicology, College of Pharmacy
- Nora Eccles Harrison Cardiovascular Research and Training Institute
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, USA
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6
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Huo JL, Feng Q, Pan S, Fu WJ, Liu Z, Liu Z. Diabetic cardiomyopathy: Early diagnostic biomarkers, pathogenetic mechanisms, and therapeutic interventions. Cell Death Discov 2023; 9:256. [PMID: 37479697 PMCID: PMC10362058 DOI: 10.1038/s41420-023-01553-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/06/2023] [Accepted: 07/12/2023] [Indexed: 07/23/2023] Open
Abstract
Diabetic cardiomyopathy (DCM) mainly refers to myocardial metabolic dysfunction caused by high glucose, and hyperglycemia is an independent risk factor for cardiac function in the absence of coronary atherosclerosis and hypertension. DCM, which is a severe complication of diabetes, has become the leading cause of heart failure in diabetic patients. The initial symptoms are inconspicuous, and patients gradually exhibit left ventricular dysfunction and eventually develop total heart failure, which brings a great challenge to the early diagnosis of DCM. To date, the underlying pathological mechanisms of DCM are complicated and have not been fully elucidated. Although there are therapeutic strategies available for DCM, the treatment is mainly focused on controlling blood glucose and blood lipids, and there is a lack of effective drugs targeting myocardial injury. Thus, a large percentage of patients with DCM inevitably develop heart failure. Given the neglected initial symptoms, the intricate cellular and molecular mechanisms, and the lack of available drugs, it is necessary to explore early diagnostic biomarkers, further understand the signaling pathways involved in the pathogenesis of DCM, summarize the current therapeutic strategies, and develop new targeted interventions.
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Affiliation(s)
- Jin-Ling Huo
- Traditional Chinese Medicine Integrated Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China
- Research Institute of Nephrology, Zhengzhou University, Zhengzhou, 450052, P. R. China
- Henan Province Research Center For Kidney Disease, Zhengzhou, 450052, P. R. China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, 450052, P. R. China
| | - Qi Feng
- Traditional Chinese Medicine Integrated Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China
- Research Institute of Nephrology, Zhengzhou University, Zhengzhou, 450052, P. R. China
- Henan Province Research Center For Kidney Disease, Zhengzhou, 450052, P. R. China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, 450052, P. R. China
| | - Shaokang Pan
- Traditional Chinese Medicine Integrated Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China
- Research Institute of Nephrology, Zhengzhou University, Zhengzhou, 450052, P. R. China
- Henan Province Research Center For Kidney Disease, Zhengzhou, 450052, P. R. China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, 450052, P. R. China
| | - Wen-Jia Fu
- Traditional Chinese Medicine Integrated Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China
- Research Institute of Nephrology, Zhengzhou University, Zhengzhou, 450052, P. R. China
- Henan Province Research Center For Kidney Disease, Zhengzhou, 450052, P. R. China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, 450052, P. R. China
| | - Zhangsuo Liu
- Traditional Chinese Medicine Integrated Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.
- Research Institute of Nephrology, Zhengzhou University, Zhengzhou, 450052, P. R. China.
- Henan Province Research Center For Kidney Disease, Zhengzhou, 450052, P. R. China.
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, 450052, P. R. China.
| | - Zhenzhen Liu
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.
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7
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GLUT4 translocation and dispersal operate in multiple cell types and are negatively correlated with cell size in adipocytes. Sci Rep 2022; 12:20535. [PMID: 36446811 PMCID: PMC9708847 DOI: 10.1038/s41598-022-24736-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/18/2022] [Indexed: 11/30/2022] Open
Abstract
The regulated translocation of the glucose transporter, GLUT4, to the surface of adipocytes and muscle is a key action of insulin. This is underpinned by the delivery and fusion of GLUT4-containing vesicles with the plasma membrane. Recent studies have revealed that a further action of insulin is to mediate the dispersal of GLUT4 molecules away from the site of GLUT4 vesicle fusion with the plasma membrane. Although shown in adipocytes, whether insulin-stimulated dispersal occurs in other cells and/or is exhibited by other proteins remains a matter of debate. Here we show that insulin stimulates GLUT4 dispersal in the plasma membrane of adipocytes, induced pluripotent stem cell-derived cardiomyocytes and HeLa cells, suggesting that this phenomenon is specific to GLUT4 expressed in all cell types. By contrast, insulin-stimulated dispersal of TfR was not observed in HeLa cells, suggesting that the mechanism may be unique to GLUT4. Consistent with dispersal being an important physiological mechanism, we observed that insulin-stimulated GLUT4 dispersal is reduced under conditions of insulin resistance. Adipocytes of different sizes have been shown to exhibit distinct metabolic properties: larger adipocytes exhibit reduced insulin-stimulated glucose transport compared to smaller cells. Here we show that both GLUT4 delivery to the plasma membrane and GLUT4 dispersal are reduced in larger adipocytes, supporting the hypothesis that larger adipocytes are refractory to insulin challenge compared to their smaller counterparts, even within a supposedly homogeneous population of cells.
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Chen YC, Wang QQ, Wang YH, Zhuo HL, Dai RZ. Intravenous regular insulin is an efficient and safe procedure for obtaining high-quality cardiac 18F-FDG PET images: an open-label, single-center, randomized controlled prospective trial. J Nucl Cardiol 2022; 29:239-247. [PMID: 32533427 DOI: 10.1007/s12350-020-02219-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/26/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND An open-label, single-center, randomized controlled prospective trial was performed to assess the efficiency and safety of an insulin loading procedure to obtain high-quality cardiac 18F-FDG PET/CT images for patients with coronary artery disease (CAD). METHODS Between November 22, 2018 and August 15, 2019, 60 patients with CAD scheduled for cardiac 18F-FDG PET/CT imaging in our department were randomly allocated in a 1:1 ratio to receive an insulin or standardized glucose loading procedure for cardiac 18F-FDG imaging. The primary outcome was the ratio of interpretable images (high-quality images defined as myocardium-to-liver ratios ≥ 1). The secondary outcome was the patient preparation time (time interval between administration of insulin/glucose and 18F-FDG injection). Hypoglycemia events were recorded. RESULTS The ratio of interpretable cardiac PET images in the insulin loading group surpassed the glucose loading group (30/30 vs. 25/30, P = 0.026). Preparation time was 71±2 min shorter for the insulin loading group than for the glucose loading group (P < 0.01). Two and six hypoglycemia cases occurred in the insulin and glucose loading groups, respectively. CONCLUSION The insulin loading protocol was a quicker, more efficient, and safer preparation for gaining high-quality cardiac 18F-FDG images.
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Affiliation(s)
- Yang Chun Chen
- Department of Nuclear Medicine, Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China.
- Medical College, Huaqiao University, South Anji Road 1028#, Fengze District, Quanzhou, 362000, China.
| | - Qing Qing Wang
- Department of Nuclear Medicine, Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China
| | - Yue Hui Wang
- Department of Nuclear Medicine, Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China
| | - Hui Lin Zhuo
- Department of Cardiology, Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China
| | - Ruo Zhu Dai
- Department of Cardiology, Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China
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Jankauskas SS, Kansakar U, Varzideh F, Wilson S, Mone P, Lombardi A, Gambardella J, Santulli G. Heart failure in diabetes. Metabolism 2021; 125:154910. [PMID: 34627874 PMCID: PMC8941799 DOI: 10.1016/j.metabol.2021.154910] [Citation(s) in RCA: 86] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 12/16/2022]
Abstract
Heart failure and cardiovascular disorders represent the leading cause of death in diabetic patients. Here we present a systematic review of the main mechanisms underlying the development of diabetic cardiomyopathy. We also provide an excursus on the relative contribution of cardiomyocytes, fibroblasts, endothelial and smooth muscle cells to the pathophysiology of heart failure in diabetes. After having described the preclinical tools currently available to dissect the mechanisms of this complex disease, we conclude with a section on the most recent updates of the literature on clinical management.
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Affiliation(s)
- Stanislovas S Jankauskas
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA; Department of Molecular Pharmacology, Einstein Institute for Neuroimmunology and Inflammation, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Urna Kansakar
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA; Department of Molecular Pharmacology, Einstein Institute for Neuroimmunology and Inflammation, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Fahimeh Varzideh
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA; Department of Molecular Pharmacology, Einstein Institute for Neuroimmunology and Inflammation, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Scott Wilson
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Pasquale Mone
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Angela Lombardi
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Jessica Gambardella
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA; Department of Molecular Pharmacology, Einstein Institute for Neuroimmunology and Inflammation, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA; International Translational Research and Medical Education (ITME), Department of Advanced Biomedical Science, "Federico II" University, 80131 Naples, Italy
| | - Gaetano Santulli
- Department of Medicine, Fleischer Institute for Diabetes and Metabolism (FIDAM), Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Albert Einstein College of Medicine, New York, NY 10461, USA; Department of Molecular Pharmacology, Einstein Institute for Neuroimmunology and Inflammation, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA; International Translational Research and Medical Education (ITME), Department of Advanced Biomedical Science, "Federico II" University, 80131 Naples, Italy.
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Borg ML, Massart J, De Castro Barbosa T, Archilla-Ortega A, Smith JAB, Lanner JT, Alsina-Fernandez J, Yaden B, Culver AE, Karlsson HKR, Brozinick JT, Zierath JR. Modified UCN2 peptide treatment improves skeletal muscle mass and function in mouse models of obesity-induced insulin resistance. J Cachexia Sarcopenia Muscle 2021; 12:1232-1248. [PMID: 34342159 PMCID: PMC8517345 DOI: 10.1002/jcsm.12746] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/25/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Type 2 diabetes and obesity are often seen concurrently with skeletal muscle wasting, leading to further derangements in function and metabolism. Muscle wasting remains an unmet need for metabolic disease, and new approaches are warranted. The neuropeptide urocortin 2 (UCN2) and its receptor corticotropin releasing factor receptor 2 (CRHR2) are highly expressed in skeletal muscle and play a role in regulating energy balance, glucose metabolism, and muscle mass. The aim of this study was to investigate the effects of modified UCN2 peptides as a pharmaceutical therapy to counteract the loss of skeletal muscle mass associated with obesity and casting immobilization. METHODS High-fat-fed mice (C57Bl/6J; 26 weeks old) and ob/ob mice (11 weeks old) were injected daily with a PEGylated (Compound A) and non-PEGylated (Compound B) modified human UCN2 at 0.3 mg/kg subcutaneously for 14 days. A separate group of chow-fed C57Bl/6J mice (12 weeks old) was subjected to hindlimb cast immobilization and, after 1 week, received daily injections with Compound A. In vivo functional tests were performed to measure protein synthesis rates and skeletal muscle function. Ex vivo functional and molecular tests were performed to measure contractile force and signal transduction of catabolic and anabolic pathways in skeletal muscle. RESULTS Skeletal muscles (extensor digitorum longus, soleus, and tibialis anterior) from high-fat-fed mice treated with Compound A were ~14% heavier than muscles from vehicle-treated mice. Chronic treatment with modified UCN2 peptides altered the expression of structural genes and transcription factors in skeletal muscle in high-fat diet-induced obesity including down-regulation of Trim63 and up-regulation of Nr4a2 and Igf1 (P < 0.05 vs. vehicle). Signal transduction via both catabolic and anabolic pathways was increased in tibialis anterior muscle, with increased phosphorylation of ribosomal protein S6 at Ser235/236 , FOXO1 at Ser256 , and ULK1 at Ser317 , suggesting that UCN2 treatment modulates protein synthesis and degradation pathways (P < 0.05 vs. vehicle). Acutely, a single injection of Compound A in drug-naïve mice had no effect on the rate of protein synthesis in skeletal muscle, as measured via the surface sensing of translation method, while the expression of Nr4a3 and Ppargc1a4 was increased (P < 0.05 vs. vehicle). Compound A treatment prevented the loss of force production from disuse due to casting. Compound B treatment increased time to fatigue during ex vivo contractions of fast-twitch extensor digitorum longus muscle. Compound A and B treatment increased lean mass and rates of skeletal muscle protein synthesis in ob/ob mice. CONCLUSIONS Modified human UCN2 is a pharmacological candidate for the prevention of the loss of skeletal muscle mass associated with obesity and immobilization.
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Affiliation(s)
- Melissa L Borg
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Julie Massart
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Thais De Castro Barbosa
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Adrià Archilla-Ortega
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Jonathon A B Smith
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Johanna T Lanner
- Department of Physiology and Pharmacology, Section for Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden
| | | | - Benjamin Yaden
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN, USA
| | - Alexander E Culver
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN, USA
| | - Håkan K R Karlsson
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Joseph T Brozinick
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN, USA
| | - Juleen R Zierath
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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11
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De Jong KA, Nikolaev VO. Multifaceted remodelling of cAMP microdomains driven by different aetiologies of heart failure. FEBS J 2021; 288:6603-6622. [DOI: 10.1111/febs.15706] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/22/2020] [Accepted: 01/06/2021] [Indexed: 12/14/2022]
Affiliation(s)
- Kirstie A. De Jong
- Institute of Experimental Cardiovascular Research University Medical Center Hamburg‐Eppendorf Hamburg Germany
- German Center for Cardiovascular Research (DZHK) partner site Hamburg/Kiel/Lübeck D‐20246 Hamburg Germany
| | - Viacheslav O. Nikolaev
- Institute of Experimental Cardiovascular Research University Medical Center Hamburg‐Eppendorf Hamburg Germany
- German Center for Cardiovascular Research (DZHK) partner site Hamburg/Kiel/Lübeck D‐20246 Hamburg Germany
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12
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Arkadievich OD. Metabolic markers of myocardium insulin resistance in dogs with heart failure. Open Vet J 2021; 10:363-370. [PMID: 33614430 PMCID: PMC7830177 DOI: 10.4314/ovj.v10i4.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 09/21/2020] [Indexed: 12/14/2022] Open
Abstract
Background Heart failure syndrome is an aspect of primary or secondary heart disease and is associated with decompensation, formation, and activation of pathological interactions between regulation systems. This results in myocardial energy metabolism alteration. This study was carried out to defy some metabolic aspects of myocardial tissue insulin resistance (IRM) development in canine heart failure. Aim To investigate the myocardial tissue concentration of adenosine triphosphate (ATP), glucose transporters 1 and 4, pyruvate dehydrogenase (PDH), hexokinase 2, insulin receptor (InsR), and adropin (ADR) protein and to screen metabolic changes and IRM in canine myocardium with heart failure. Methods We studied 28 dogs of different sexes, ages, and breeds. Groups were formed according to primary pathology: apparently healthy dogs (HD, n = 6); dogs with CDVD (CDVDD, n = 8); dogs with DCM (DCMD, n = 6); and dogs with doxorubicin chemotherapy and doxorubicin-induced cardiomyopathy (DoxCMD, n = 8). Animals in the study were diagnosed for primary disease by standard methods and algorithms. Animals were euthanized due to incurable neurological disease, refractory heart failure, or by owners will. The material was obtained immediately after death, fixed in liquid nitrogen, and stored in -80°C refrigerator. Studied proteins concentrations were analyzed in a specialized research laboratory, using ELISA kits, provided by Cloud-Clone Corp. Results ATP, GLUT1, and GLUT4 concentrations in myocardial tissue from the valvular disease group did not differ from the HD group. In CDVD, we found depression of PDH, hexokinase II (HX2), and ADR concentrations in comparison to HD. InsR was significantly lower in the CDVD and DoxCMD groups in comparison to the HD group, but in the DCM group, it was twofold higher than in the HD group. In the DCMD and DoxCMD groups, all parameters were lower than in the HD group. ATP, HX2, ADR, GLUT1, and GLUT4 were higher in the CDVD group, than in the DCM and DoxCM groups. PDH in the CDVD and DoxCM groups did not differ. PDH was depleted in the DCM to CDVD and DoxCM groups. InsR did not differ between the CDVD and DoxCM groups, but was upregulated in the DCM to CDVD and DoxCM groups. Conclusion Development of myocardial tissue IRM is a part of the structural, functional and metabolic remodeling in dogs with heart failure of different etiology. At the late stages, we found significant changes in energy supply availability and production in the myocardium.
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13
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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: 95] [Impact Index Per Article: 23.8] [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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14
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Camus SM, Camus MD, Figueras-Novoa C, Boncompain G, Sadacca LA, Esk C, Bigot A, Gould GW, Kioumourtzoglou D, Perez F, Bryant NJ, Mukherjee S, Brodsky FM. CHC22 clathrin mediates traffic from early secretory compartments for human GLUT4 pathway biogenesis. J Cell Biol 2020; 219:133472. [PMID: 31863584 PMCID: PMC7039200 DOI: 10.1083/jcb.201812135] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 08/02/2019] [Accepted: 10/09/2019] [Indexed: 12/29/2022] Open
Abstract
Blood glucose clearance relies on insulin-stimulated exocytosis of glucose transporter 4 (GLUT4) from sites of sequestration in muscle and fat. This work demonstrates that, in humans, CHC22 clathrin controls GLUT4 traffic from the ER-to-Golgi intermediate compartment to sites of sequestration during GLUT4 pathway biogenesis. Glucose transporter 4 (GLUT4) is sequestered inside muscle and fat and then released by vesicle traffic to the cell surface in response to postprandial insulin for blood glucose clearance. Here, we map the biogenesis of this GLUT4 traffic pathway in humans, which involves clathrin isoform CHC22. We observe that GLUT4 transits through the early secretory pathway more slowly than the constitutively secreted GLUT1 transporter and localize CHC22 to the ER-to-Golgi intermediate compartment (ERGIC). CHC22 functions in transport from the ERGIC, as demonstrated by an essential role in forming the replication vacuole of Legionella pneumophila bacteria, which requires ERGIC-derived membrane. CHC22 complexes with ERGIC tether p115, GLUT4, and sortilin, and downregulation of either p115 or CHC22, but not GM130 or sortilin, abrogates insulin-responsive GLUT4 release. This indicates that CHC22 traffic initiates human GLUT4 sequestration from the ERGIC and defines a role for CHC22 in addition to retrograde sorting of GLUT4 after endocytic recapture, enhancing pathways for GLUT4 sequestration in humans relative to mice, which lack CHC22.
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Affiliation(s)
- Stéphane M Camus
- Department of Bioengineering and Therapeutic Sciences and Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA.,Department of Microbiology and Immunology and the G.W. Hooper Foundation, University of California, San Francisco, San Francisco, CA.,Division of Biosciences, University College London, London, UK
| | - Marine D Camus
- Department of Bioengineering and Therapeutic Sciences and Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA.,Department of Microbiology and Immunology and the G.W. Hooper Foundation, University of California, San Francisco, San Francisco, CA.,Division of Biosciences, University College London, London, UK
| | | | - Gaelle Boncompain
- Institut Curie, PSL Research University, CNRS UMR 144, Paris, France
| | | | - Christopher Esk
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Anne Bigot
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Association Institut de Myologie, UMR S974 Centre for Research in Myology, Paris, France
| | - Gwyn W Gould
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Dimitrios Kioumourtzoglou
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Biology and York Biomedical Research Institute, University of York, York, UK
| | - Franck Perez
- Institut Curie, PSL Research University, CNRS UMR 144, Paris, France
| | - Nia J Bryant
- Department of Biology and York Biomedical Research Institute, University of York, York, UK
| | - Shaeri Mukherjee
- Department of Microbiology and Immunology and the G.W. Hooper Foundation, University of California, San Francisco, San Francisco, CA
| | - Frances M Brodsky
- Department of Bioengineering and Therapeutic Sciences and Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA.,Department of Microbiology and Immunology and the G.W. Hooper Foundation, University of California, San Francisco, San Francisco, CA.,Division of Biosciences, University College London, London, UK
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15
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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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16
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Woolcott OO, Ader M, Bergman RN. Glucose homeostasis during short-term and prolonged exposure to high altitudes. Endocr Rev 2015; 36:149-73. [PMID: 25675133 PMCID: PMC4399271 DOI: 10.1210/er.2014-1063] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Most of the literature related to high altitude medicine is devoted to the short-term effects of high-altitude exposure on human physiology. However, long-term effects of living at high altitudes may be more important in relation to human disease because more than 400 million people worldwide reside above 1500 m. Interestingly, individuals living at higher altitudes have a lower fasting glycemia and better glucose tolerance compared with those who live near sea level. There is also emerging evidence of the lower prevalence of both obesity and diabetes at higher altitudes. The mechanisms underlying improved glucose control at higher altitudes remain unclear. In this review, we present the most current evidence about glucose homeostasis in residents living above 1500 m and discuss possible mechanisms that could explain the lower fasting glycemia and lower prevalence of obesity and diabetes in this population. Understanding the mechanisms that regulate and maintain the lower fasting glycemia in individuals who live at higher altitudes could lead to new therapeutics for impaired glucose homeostasis.
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Affiliation(s)
- Orison O Woolcott
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048
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17
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Bradley H, Shaw CS, Worthington PL, Shepherd SO, Cocks M, Wagenmakers AJM. Quantitative immunofluorescence microscopy of subcellular GLUT4 distribution in human skeletal muscle: effects of endurance and sprint interval training. Physiol Rep 2014; 2:2/7/e12085. [PMID: 25052490 PMCID: PMC4187550 DOI: 10.14814/phy2.12085] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Increases in insulin‐mediated glucose uptake following endurance training (ET) and sprint interval training (SIT) have in part been attributed to concomitant increases in glucose transporter 4 (GLUT4) protein content in skeletal muscle. This study used an immunofluorescence microscopy method to investigate changes in subcellular GLUT4 distribution and content following ET and SIT. Percutaneous muscle biopsy samples were taken from the m. vastus lateralis of 16 sedentary males in the overnight fasted state before and after 6 weeks of ET and SIT. An antibody was fully validated and used to show large (> 1 μm) and smaller (<1 μm) GLUT4‐containing clusters. The large clusters likely represent trans‐Golgi network stores and the smaller clusters endosomal stores and GLUT4 storage vesicles (GSVs). Density of GLUT4 clusters was higher at the fibre periphery especially in perinuclear regions. A less dense punctate distribution was seen in the rest of the muscle fibre. Total GLUT4 fluorescence intensity increased in type I and type II fibres following both ET and SIT. Large GLUT4 clusters increased in number and size in both type I and type II fibres, while the smaller clusters increased in size. The greatest increases in GLUT4 fluorescence intensity occurred within the 1 μm layer immediately adjacent to the PM. The increase in peripheral localisation and protein content of GLUT4 following ET and SIT is likely to contribute to the improvements in glucose homeostasis observed after both training modes. e12085 This paper first describes the development of a novel confocal immunofluorescence microscopy method that allows quantitation of GLUT4 content in the plasma membrane and 1 µm layers below it in a muscle fibre‐type specific manner. Skeletal muscle biopsies obtained from sedentary young men before and after 6 weeks of traditional endurance training (ET) and sprint interval training (SIT) were then analysed to show for the first time increases in large and small GLUT4 clusters with greater increases in the layer within 1 µm of the plasma membrane, which is the layer from which most GLUT4 fusion events emanate. This training‐induced redistribution is likely to contribute to the increase in insulin sensitivity seen following both ET and SIT.
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Affiliation(s)
- Helen Bradley
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Christopher S Shaw
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Vic., Australia
| | - Philip L Worthington
- Computational Biology, Discovery Sciences, AstraZeneca, Alderley Park, Macclesfield, UK
| | - Sam O Shepherd
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Matthew Cocks
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Anton J M Wagenmakers
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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18
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Insulin- and contraction-induced glucose transporter 4 traffic in muscle: insights from a novel imaging approach. Exerc Sport Sci Rev 2014; 41:77-86. [PMID: 23072821 DOI: 10.1097/jes.0b013e318275574c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Insulin- and contraction-mediated glucose transporter 4 (GLUT4) trafficking have different kinetics in mature skeletal muscle. Intravital imaging indicates that insulin-stimulated GLUT4 trafficking differs between t-tubules and sarcolemma. In contrast, contraction-induced GLUT4 trafficking does not differ between membrane surfaces. This distinction likely is caused by differences in the underlying signaling pathways regulating GLUT4 vesicle depletion, GLUT4 membrane fusion, and GLUT4 reinternalization.
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19
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Hoshino S, Sakamoto K, Vassilopoulos S, Camus SM, Griffin CA, Esk C, Torres JA, Ohkoshi N, Ishii A, Tamaoka A, Funke BH, Kucherlapati R, Margeta M, Rando TA, Brodsky FM. The CHC22 clathrin-GLUT4 transport pathway contributes to skeletal muscle regeneration. PLoS One 2013; 8:e77787. [PMID: 24204966 PMCID: PMC3813726 DOI: 10.1371/journal.pone.0077787] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 09/13/2013] [Indexed: 01/08/2023] Open
Abstract
Mobilization of the GLUT4 glucose transporter from intracellular storage vesicles provides a mechanism for insulin-responsive glucose import into skeletal muscle. In humans, clathrin isoform CHC22 participates in formation of the GLUT4 storage compartment in skeletal muscle and fat. CHC22 function is limited to retrograde endosomal sorting and is restricted in its tissue expression and species distribution compared to the conserved CHC17 isoform that mediates endocytosis and several other membrane traffic pathways. Previously, we noted that CHC22 was expressed at elevated levels in regenerating rat muscle. Here we investigate whether the GLUT4 pathway in which CHC22 participates could play a role in muscle regeneration in humans and we test this possibility using CHC22-transgenic mice, which do not normally express CHC22. We observed that GLUT4 expression is elevated in parallel with that of CHC22 in regenerating skeletal muscle fibers from patients with inflammatory and other myopathies. Regenerating human myofibers displayed concurrent increases in expression of VAMP2, another regulator of GLUT4 transport. Regenerating fibers from wild-type mouse skeletal muscle injected with cardiotoxin also showed increased levels of GLUT4 and VAMP2. We previously demonstrated that transgenic mice expressing CHC22 in their muscle over-sequester GLUT4 and VAMP2 and have defective GLUT4 trafficking leading to diabetic symptoms. In this study, we find that muscle regeneration rates in CHC22 mice were delayed compared to wild-type mice, and myoblasts isolated from these mice did not proliferate in response to glucose. Additionally, CHC22-expressing mouse muscle displayed a fiber type switch from oxidative to glycolytic, similar to that observed in type 2 diabetic patients. These observations implicate the pathway for GLUT4 transport in regeneration of both human and mouse skeletal muscle, and demonstrate a role for this pathway in maintenance of muscle fiber type. Extrapolating these findings, CHC22 and GLUT4 can be considered markers of muscle regeneration in humans.
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Affiliation(s)
- Sachiko Hoshino
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
- Department of Neurology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kazuho Sakamoto
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Stéphane Vassilopoulos
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Stéphane M. Camus
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Christine A. Griffin
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Christopher Esk
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Jorge A. Torres
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Norio Ohkoshi
- Department of Health, Faculty of Health Sciences, National University Corporation Tsukuba University of Technology, Tsukuba, Ibaraki, Japan
| | - Akiko Ishii
- Department of Neurology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Akira Tamaoka
- Department of Neurology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Birgit H. Funke
- Departments of Genetics and Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Raju Kucherlapati
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, United States of America
| | - Marta Margeta
- Department of Pathology, University of California San Francisco, San Francisco, California, United States of America
| | - Thomas A. Rando
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, United States of America
| | - Frances M. Brodsky
- The G.W. Hooper Foundation, Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, and Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
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20
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Toward an understanding of the complete NCX1 lifetime in the cardiac sarcolemma. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:345-52. [PMID: 23224893 DOI: 10.1007/978-1-4614-4756-6_29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The density of Na/Ca exchangers (NCX1) in the cardiac sarcolemma, like all plasma membrane proteins, will be influenced by (and ultimately determined by) the function of membrane insertion and retrieval processes (i.e., exo- and endocytic mechanisms). Progress in understanding these processes in cardiac muscle faces many biological and methodological complexities and hurdles. As described here, we are attempting to overcome these hurdles to study more adequately the assembly and disassembly of the cardiac sarcolemma, in general, and the control of NCX1 by membrane trafficking processes in particular. First, we have developed improved noninvasive methods to monitor the cellular capacitance of cardiac tissue (NIC) over periods of hours. Thus, we can study long-term changes of total membrane area. Second, we have developed mice that express fusion proteins of NCX1 with the pHluorin green protein. Thus, we can determine the membrane disposition of NCX1, and changes thereof, on-line in intact cardiac muscle.
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21
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Dalla-Riva J, Stenkula KG, Petrlova J, Lagerstedt JO. Discoidal HDL and apoA-I-derived peptides improve glucose uptake in skeletal muscle. J Lipid Res 2013; 54:1275-82. [PMID: 23471027 PMCID: PMC3653404 DOI: 10.1194/jlr.m032904] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Lipid-free apoA-I and mature spherical HDL have been shown to induce glucose uptake in skeletal muscle. To exploit apoA-I and HDL states for diabetes therapy, further understanding of interaction between muscle and apoA-I is required. This study has examined whether nascent discoidal HDL, in which apoA-I attains a different conformation from mature HDL and lipid-free states, could induce muscle glucose uptake and whether a specific domain of apoA-I can mediate this effect. Using L6 myotubes stimulated with synthetic reconstituted discoidal HDL (rHDL), we show a glucose uptake effect comparable to insulin. Increased plasma membrane GLUT4 levels in ex vivo rHDL-stimulated myofibers from HA-GLUT4-GFP transgenic mice support this observation. rHDL increased phosphorylation of AMP kinase (AMPK) and acetyl-coA carboxylase (ACC) but not Akt. A survey of domain-specific peptides of apoA-I showed that the lipid-free C-terminal 190-243 fragment increases plasma membrane GLUT4, promotes glucose uptake, and activates AMPK signaling but not Akt. This may be explained by changes in α-helical content of 190-243 fragment versus full-length lipid-free apoA-I as assessed by circular dichroism spectroscopy. Discoidal HDL and the 190-243 peptide of apoA-I are potent agonists of glucose uptake in skeletal muscle, and the C-terminal α-helical content of apoA-I may be an important determinant of this effect.
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Affiliation(s)
- Jonathan Dalla-Riva
- Department of Experimental Medical Science, Lund University, S-221 84 Lund, Sweden
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22
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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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23
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Sussman MA, Völkers M, Fischer K, Bailey B, Cottage CT, Din S, Gude N, Avitabile D, Alvarez R, Sundararaman B, Quijada P, Mason M, Konstandin MH, Malhowski A, Cheng Z, Khan M, McGregor M. Myocardial AKT: the omnipresent nexus. Physiol Rev 2011; 91:1023-70. [PMID: 21742795 PMCID: PMC3674828 DOI: 10.1152/physrev.00024.2010] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
One of the greatest examples of integrated signal transduction is revealed by examination of effects mediated by AKT kinase in myocardial biology. Positioned at the intersection of multiple afferent and efferent signals, AKT exemplifies a molecular sensing node that coordinates dynamic responses of the cell in literally every aspect of biological responses. The balanced and nuanced nature of homeostatic signaling is particularly essential within the myocardial context, where regulation of survival, energy production, contractility, and response to pathological stress all flow through the nexus of AKT activation or repression. Equally important, the loss of regulated AKT activity is primarily the cause or consequence of pathological conditions leading to remodeling of the heart and eventual decompensation. This review presents an overview compendium of the complex world of myocardial AKT biology gleaned from more than a decade of research. Summarization of the widespread influence that AKT exerts upon myocardial responses leaves no doubt that the participation of AKT in molecular signaling will need to be reckoned with as a seemingly omnipresent regulator of myocardial molecular biological responses.
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Affiliation(s)
- Mark A Sussman
- Department of Biology, San Diego State University, SDSU Heart Institute, San Diego, California 92182, USA.
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Subcellular trafficking of the substrate transporters GLUT4 and CD36 in cardiomyocytes. Cell Mol Life Sci 2011; 68:2525-38. [PMID: 21547502 PMCID: PMC3134709 DOI: 10.1007/s00018-011-0690-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 04/01/2011] [Accepted: 04/12/2011] [Indexed: 12/16/2022]
Abstract
Cardiomyocytes use glucose as well as fatty acids for ATP production. These substrates are transported into the cell by glucose transporter 4 (GLUT4) and the fatty acid transporter CD36. Besides being located at the sarcolemma, GLUT4 and CD36 are stored in intracellular compartments. Raised plasma insulin concentrations and increased cardiac work will stimulate GLUT4 as well as CD36 to translocate to the sarcolemma. As so far studied, signaling pathways that regulate GLUT4 translocation similarly affect CD36 translocation. During the development of insulin resistance and type 2 diabetes, CD36 becomes permanently localized at the sarcolemma, whereas GLUT4 internalizes. This juxtaposed positioning of GLUT4 and CD36 is important for aberrant substrate uptake in the diabetic heart: chronically increased fatty acid uptake at the expense of glucose. To explain the differences in subcellular localization of GLUT4 and CD36 in type 2 diabetes, recent research has focused on the role of proteins involved in trafficking of cargo between subcellular compartments. Several of these proteins appear to be similarly involved in both GLUT4 and CD36 translocation. Others, however, have different roles in either GLUT4 or CD36 translocation. These trafficking components, which are differently involved in GLUT4 or CD36 translocation, may be considered novel targets for the development of therapies to restore the imbalanced substrate utilization that occurs in obesity, insulin resistance and diabetic cardiomyopathy.
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25
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Translocation of the Na+/H+ exchanger 1 (NHE1) in cardiomyocyte responses to insulin and energy-status signalling. Biochem J 2011; 432:515-23. [PMID: 20868366 PMCID: PMC2995423 DOI: 10.1042/bj20100717] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Na+/H+ exchanger NHE1 is a highly regulated membrane protein that is required for pH homoeostasis in cardiomyocytes. The activation of NHE1 leads to proton extrusion, which is essential for counteracting cellular acidity that occurs following increased metabolic activity or ischaemia. The activation of NHE1 intrinsic catalytic activity has been well characterized and established experimentally. However, we have examined in the present study whether a net translocation of NHE1 to the sarcolemma of cardiomyocytes may also be involved in the activation process. We have determined the distribution of NHE1 by means of immunofluorescence microscopy and cell-surface biotinylation. We have discovered changes in the distribution of NHE1 that occur when cardiomyocytes are stimulated with insulin that are PI3K (phosphoinositide 3-kinase)-dependent. Translocation of NHE1 also occurs when cardiomyocytes are challenged by hypoxia, or inhibition of mitochondrial oxidative metabolism or electrically induced contraction, but these responses occur through a PI3K-independent process. As the proposed additional level of control of NHE1 through translocation was unexpected, we have compared this process with the well-established translocation of the glucose transporter GLUT4. In immunofluorescence microscopy comparisons, the translocation of NHE1 and GLUT4 to the sarcolemma that occur in response to insulin appear to be very similar. However, in basal unstimulated cells the two proteins are mainly located, with the exception of some co-localization in the perinuclear region, in distinct subcellular compartments. We propose that the mechanisms of translocation of NHE1 and GLUT4 are linked such that they provide spatially and temporally co-ordinated responses to cardiac challenges that necessitate re-adjustments in glucose transport, glucose metabolism and cell pH.
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Chen S, Wasserman DH, MacKintosh C, Sakamoto K. Mice with AS160/TBC1D4-Thr649Ala knockin mutation are glucose intolerant with reduced insulin sensitivity and altered GLUT4 trafficking. Cell Metab 2011; 13:68-79. [PMID: 21195350 PMCID: PMC3081066 DOI: 10.1016/j.cmet.2010.12.005] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 07/31/2010] [Accepted: 10/12/2010] [Indexed: 01/24/2023]
Abstract
AS160 has emerged as a key player in insulin-mediated glucose transport through controlling GLUT4 trafficking, which is thought to be regulated by insulin-stimulated phosphorylation of sites including the 14-3-3 binding phospho-Thr649 (equivalent to Thr642 in human AS160). To define physiological roles of AS160-Thr649 phosphorylation and 14-3-3 binding in glucose homeostasis, we substituted this residue by a nonphosphorylatable alanine by knockin mutation in mice. The mutant protein was expressed at normal levels, while insulin-stimulated AS160 binding to 14-3-3s was abolished in homozygous knockin mice. These animals displayed impaired glucose disposal and insulin sensitivity, which were associated with decreased glucose uptake in vivo. Insulin-stimulated glucose transport and cell surface GLUT4 content were reduced in isolated muscles, but not in adipocytes. These results provide genetic evidence that insulin-induced AS160-Thr649 phosphorylation and/or its binding to 14-3-3 play an important role in regulating whole-body glucose homeostasis, at least in part through regulating GLUT4 trafficking in muscle.
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Affiliation(s)
- Shuai Chen
- MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK.
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27
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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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28
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Lauritzen HP, Galbo H, Toyoda T, Goodyear LJ. Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice. Diabetes 2010; 59:2134-44. [PMID: 20622170 PMCID: PMC2927934 DOI: 10.2337/db10-0233] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process. RESEARCH DESIGN AND METHODS Confocal imaging was used to visualize GLUT4-enhanced green fluorescent protein (EGFP) in transfected quadriceps muscle fibers in living mice subjected to contractions or the AMPK-activator AICAR. RESULTS Contraction increased GLUT4-EGFP translocation from intracellular vesicle depots to both the sarcolemma and t-tubules with similar kinetics, although translocation was greater with contractions elicited by higher voltage. Re-internalization of GLUT4 did not begin until 10 min after contractions ceased and was not complete until 130 min after contractions. AICAR increased GLUT4-EGFP translocation to both sarcolemma and t-tubules with similar kinetics. Ablation of AMPKalpha2 activity in AMPKalpha2 inactive transgenic mice did not change GLUT4-EGFP's basal localization, contraction-stimulated intracellular GLUT4-EGFP vesicle depletion, translocation, or re-internalization, but diminished AICAR-induced translocation. CONCLUSIONS We have developed a novel imaging system to study contraction-stimulated GLUT4 translocation in living mice. Contractions increase GLUT4 translocation to the sarcolemma and t-tubules with similar kinetics and do not require AMPKalpha2 activity.
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Affiliation(s)
- Hans P.M.M. Lauritzen
- Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - Henrik Galbo
- Department of Rheumatology and Institute of Inflammation Research, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Taro Toyoda
- Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - Laurie J. Goodyear
- Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
- Corresponding author: Laurie J. Goodyear,
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Abstract
Skeletal muscle is the major tissue for postprandial glucose disposal. Facilitated glucose uptake into muscle fibers is mediated by increases in surface membrane levels of the glucose transporter GLUT4 via insulin- and/or muscle contraction-mediated GLUT4 translocation. However, the regulatory mechanisms controlling GLUT4 translocation in skeletal muscle have been difficult to characterize at the cell biology level due to muscle tissue complexity. Muscle cell culture models have improved our understanding of GLUT4 translocation and glucose transport regulation, but in vitro muscle models lack many of the characteristics of mature muscle fibers. Thus, the molecular and cellular details of GLUT4 translocation in mature skeletal muscle are deficient. The objective of this review is to highlight how advances in recent experimental approaches translate into an enhanced understanding of the regulation of GLUT4 translocation and glucose transport in mature skeletal muscle.
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Affiliation(s)
- Hans P M M Lauritzen
- Integrative Physiology and Metabolism, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA.
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30
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Abstract
Skeletal muscle plays a key role in regulating whole body glucose homeostasis and severe dysfunction in insulin-mediated glucose uptake is the hallmark of insulin-resistant states and type II diabetes. Therefore it is highly pathophysiologically relevant to perform detailed studies of insulin signaling inside skeletal muscle cells in order to elucidate the specific molecular events during both normal and insulin-resistant conditions. So far, cell biology imaging techniques have been limited to in vitro cultured muscle originating from primary or cell line-based myoblasts. However, these types of cultured muscle lack many characteristics of fully differentiated muscle cells. By performing intravital protein translocation analysis directly in situ in living animals, we have been able to give a high-resolution account of the spatial and temporal details during insulin signaling in vivo in muscle that does not have the limitations of in vitro cultures. We have shown that after i.v. insulin injection, PI3-kinase activation and, in turn, GLUT4 translocation are initiated at the plasma membrane proper, the sarcolemma. Then insulin signaling progresses into the t-tubules with a velocity corresponding to the diffusion of sulforhodamine B-conjugated insulin molecules. By using intravital confocal time-lapse analysis we have revealed that the t-tubules are the membrane surface where the majority of the insulin signaling is located.
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31
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Biogenesis and regulation of insulin-responsive vesicles containing GLUT4. Curr Opin Cell Biol 2010; 22:506-12. [PMID: 20417083 DOI: 10.1016/j.ceb.2010.03.012] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 03/29/2010] [Accepted: 03/31/2010] [Indexed: 12/16/2022]
Abstract
Insulin regulates the trafficking of GLUT4 glucose transporters in fat and muscle cells. In unstimulated cells, GLUT4 is sequestered intracellularly in small, insulin-responsive vesicles. Insulin stimulates the translocation of these vesicles to the cell surface, inserting the transporters into the plasma membrane to enhance glucose uptake. Formation of the insulin-responsive vesicles requires multiple interactions among GLUT4, IRAP, LRP1, and sortilin, as well as recruitment of GGA and ACAP1 adaptors and clathrin. Once formed, the vesicles are retained within unstimulated cells by the action of TUG, Ubc9, and other proteins. In addition to acting at other steps in vesicle recycling, insulin releases this retention mechanism to promote the translocation and fusion of the vesicles at the cell surface.
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Ueda S, Kitazawa S, Ishida K, Nishikawa Y, Matsui M, Matsumoto H, Aoki T, Nozaki S, Takeda T, Tamori Y, Aiba A, Kahn CR, Kataoka T, Satoh T. Crucial role of the small GTPase Rac1 in insulin-stimulated translocation of glucose transporter 4 to the mouse skeletal muscle sarcolemma. FASEB J 2010; 24:2254-61. [PMID: 20203090 DOI: 10.1096/fj.09-137380] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The Rho family GTPase Rac1 has been implicated in the regulation of glucose uptake in myoblast cell lines. However, no evidence for the role of Rac1 has been provided by a mouse model. The purpose of this study is to test the involvement of Rac1 in insulin action in mouse skeletal muscle. Intravenous administration of insulin indeed elicited Rac1 activation in gastrocnemius muscle, suggesting the involvement of Rac1 in this signaling pathway. We then examined whether insulin-stimulated translocation of the facilitative glucose transporter GLUT4 from its storage sites to the skeletal muscle sarcolemma depends on Rac1. We show that ectopic expression of constitutively activated Rac1, as well as intravenous administration of insulin, caused translocation of GLUT4 to the gastrocnemius muscle sarcolemma, as revealed by immunofluorescent staining of a transiently expressed exofacial epitope-tagged GLUT4 reporter. Of particular note, insulin-dependent, but not constitutively activated Rac1-induced, GLUT4 translocation was markedly suppressed in skeletal muscle-specific rac1-knockout mice compared to control mice. Immunogold electron microscopic analysis of endogenous GLUT4 gave similar results. Collectively, we propose a critical role of Rac1 in insulin-dependent GLUT4 translocation to the skeletal muscle sarcolemma, which has heretofore been predicted solely by cell culture studies.
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Affiliation(s)
- Shuji Ueda
- Division of Molecular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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33
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Vassilopoulos S, Esk C, Hoshino S, Brodsky FM. [The CHC22 human clathrin heavy chain isoform, intracellular traffic of the glucose transporter GLUT4, and type 2 diabetes]. Med Sci (Paris) 2010; 26:33-6. [PMID: 20132771 DOI: 10.1051/medsci/201026133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Esk C, Chen CY, Johannes L, Brodsky FM. The clathrin heavy chain isoform CHC22 functions in a novel endosomal sorting step. ACTA ACUST UNITED AC 2010; 188:131-44. [PMID: 20065094 PMCID: PMC2812854 DOI: 10.1083/jcb.200908057] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Clathrin heavy chain 22 (CHC22) is an isoform of the well-characterized CHC17 clathrin heavy chain, a coat component of vesicles that mediate endocytosis and organelle biogenesis. CHC22 has a distinct role from CHC17 in trafficking glucose transporter 4 (GLUT4) in skeletal muscle and fat, though its transfection into HEK293 cells suggests functional redundancy. Here, we show that CHC22 is eightfold less abundant than CHC17 in muscle, other cell types have variably lower amounts of CHC22, and endogenous CHC22 and CHC17 function independently in nonmuscle and muscle cells. CHC22 was required for retrograde trafficking of certain cargo molecules from endosomes to the trans-Golgi network (TGN), defining a novel endosomal-sorting step distinguishable from that mediated by CHC17 and retromer. In muscle cells, depletion of syntaxin 10 as well as CHC22 affected GLUT4 targeting, establishing retrograde endosome-TGN transport as critical for GLUT4 trafficking. Like CHC22, syntaxin 10 is not expressed in mice but is present in humans and other vertebrates, implicating two species-restricted endosomal traffic proteins in GLUT4 transport.
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Affiliation(s)
- Christopher Esk
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
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35
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Fazakerley DJ, Holman GD, Marley A, James DE, Stöckli J, Coster ACF. Kinetic evidence for unique regulation of GLUT4 trafficking by insulin and AMP-activated protein kinase activators in L6 myotubes. J Biol Chem 2009; 285:1653-60. [PMID: 19915010 PMCID: PMC2804323 DOI: 10.1074/jbc.m109.051185] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In L6 myotubes, redistribution of a hemagglutinin (HA) epitope-tagged GLUT4 (HA-GLUT4) to the cell surface occurs rapidly in response to insulin stimulation and AMP-activated protein kinase (AMPK) activation. We have examined whether these separate signaling pathways have a convergent mechanism that leads to GLUT4 mobilization and to changes in GLUT4 recycling. HA antibody uptake on GLUT4 in the basal steady state reached a final equilibrium level that was only 81% of the insulin-stimulated level. AMPK activators (5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR) and A-769662) led to a similar level of antibody uptake to that found in insulin-stimulated cells. However, the combined responses to insulin stimulation and AMPK activation led to an antibody uptake level of ∼20% above the insulin level. Increases in antibody uptake due to insulin, but not AICAR or A-769662, treatment were reduced by both wortmannin and Akt inhibitor. The GLUT4 internalization rate constant in the basal steady state was very rapid (0.43 min−1) and was decreased during the steady-state responses to insulin (0.18 min−1), AICAR (0.16 min−1), and A-769662 (0.24 min−1). This study has revealed a nonconvergent mobilization of GLUT4 in response to activation of Akt and AMPK signaling. Furthermore, GLUT4 trafficking in L6 muscle cells is very reliant on regulated endocytosis for control of cell surface GLUT4 levels.
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Affiliation(s)
- Daniel J Fazakerley
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA27AY, United Kingdom
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36
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Cook SA, Varela-Carver A, Mongillo M, Kleinert C, Khan MT, Leccisotti L, Strickland N, Matsui T, Das S, Rosenzweig A, Punjabi P, Camici PG. Abnormal myocardial insulin signalling in type 2 diabetes and left-ventricular dysfunction. Eur Heart J 2009; 31:100-11. [PMID: 19797329 DOI: 10.1093/eurheartj/ehp396] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
AIMS Whole body and myocardial insulin resistance are features of non-insulin-dependent diabetes mellitus (NIDDM) and left-ventricular dysfunction (LVD). We determined whether abnormalities of insulin receptor substrate-1 (IRS1), IRS1-associated PI3K (IRS1-PI3K), and glucose transporter 4 (GLUT4) contribute to tissue-specific insulin resistance. METHODS AND RESULTS We collected skeletal muscle (n = 27) and myocardial biopsies (n = 24) from control patients (n = 7), patients with NIDDM (n = 9) and patients with LVD (n = 8), who were characterized by euglycaemic-hyperinsulinaemic clamp and positron emission tomography. Comparative studies were carried out in three mouse models. We demonstrate an unrecognized reduction of IRS1 in skeletal muscle of LVD patients and an unexpected increase in cardiac IRS1-PI3K activity in NIDDM and LVD patients. In NIDDM, there was a concomitant reduction in sarcolemmal GLUT4, whereas in patients with LVD sarcolemmal GLUT4 was increased. We confirm activation of IRS1-PI3K and reduction in sarcolemmal GLUT4 in the insulin resistant ob/ob mouse heart where we also demonstrate perturbation of GLUT4 docking and fusion. A direct relationship between PI3K and GLUT4 was demonstrated in mice expressing activated PI3K in the heart and increased GLUT4 at the sarcolemma was confirmed in a mouse model of LVD. CONCLUSION Our data show that the mechanisms of myocardial insulin resistance are different between NIDDM and LVD.
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Affiliation(s)
- Stuart A Cook
- Medical Research Council Clinical Sciences Centre, Imperial College, Hammersmith Hospital Campus, London W12 0NN, UK
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Klip A. The many ways to regulate glucose transporter 4. Appl Physiol Nutr Metab 2009; 34:481-7. [PMID: 19448718 DOI: 10.1139/h09-047] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Glucose uptake into skeletal muscle is primarily mediated by glucose transporter 4 (GLUT4). The number of GLUT4 polypeptides at the surface of muscle cells rises rapidly in response to insulin, contraction, depolarization, or energy deprivation. However, distinct mechanisms underlie the gain in surface GLUT4 in each case. Insulin promotes its exocytosis to the membrane, regulating vesicle movement, tethering, docking, and fusion. In contrast, muscle contraction, depolarization, and energy demand reduce GLUT4 endocytosis. The signals involved in each case also differ. Insulin utilizes Akt, Rabs, and selective actin remodelling, whereas depolarization and energy deprivation engage AMP-activated protein kinase and Ca2+-dependent signals. GLUT4 internalizes via 2 major routes that involve dynamin, but only one requires clathrin. The clathrin-independent route is slowed down by energy deprivation, and is regulated by AMP-activated protein kinase. In addition to regulation of the exocytic and endocytic movement of GLUT4, glucose uptake is also modulated through changes in the transporter's intrinsic activity. The glycolytic enzymes glyceraldehyde-3-dehydrogenase and hexokinase II contribute to such regulation, through differential binding to GLUT4.
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Affiliation(s)
- Amira Klip
- Cell Biology Program, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
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38
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Affiliation(s)
- Charisse M Orme
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8020, USA
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39
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Vassilopoulos S, Esk C, Hoshino S, Funke BH, Chen CY, Plocik AM, Wright WE, Kucherlapati R, Brodsky FM. A role for the CHC22 clathrin heavy-chain isoform in human glucose metabolism. Science 2009; 324:1192-6. [PMID: 19478182 DOI: 10.1126/science.1171529] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Intracellular trafficking of the glucose transporter GLUT4 from storage compartments to the plasma membrane is triggered in muscle and fat during the body's response to insulin. Clathrin is involved in intracellular trafficking, and in humans, the clathrin heavy-chain isoform CHC22 is highly expressed in skeletal muscle. We found a role for CHC22 in the formation of insulin-responsive GLUT4 compartments in human muscle and adipocytes. CHC22 also associated with expanded GLUT4 compartments in muscle from type 2 diabetic patients. Tissue-specific introduction of CHC22 in mice, which have only a pseudogene for this protein, caused aberrant localization of GLUT4 transport pathway components in their muscle, as well as features of diabetes. Thus, CHC22-dependent membrane trafficking constitutes a species-restricted pathway in human muscle and fat with potential implications for type 2 diabetes.
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Affiliation(s)
- Stéphane Vassilopoulos
- Department of Bioengineering and Therapeutic Sciences, University of California, School of Pharmacy, San Francisco (UCSF), San Francisco, CA 94143, USA
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40
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Lauritzen HP. In vivo imaging of GLUT4 translocationThis paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process. Appl Physiol Nutr Metab 2009; 34:420-3. [DOI: 10.1139/h09-043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In skeletal muscle, both insulin and muscle contractions mediate translocation of glucose transporter GLUT4 to the plasma membrane proper, the sarcolemma, and the specialized membrane channel network, the transverse (t)-tubules. Despite the fact that skeletal muscle glucose uptake plays a major role in normal conditions, in insulin resistance, and type II diabetes, the details of GLUT4 translocation and the intracellular signalling involved have not been fully described. A main reason is that the majority of experiments have been carried out in muscle cultures in vitro. In vitro cultured muscle is not fully differentiated and, therefore, diverges from real muscle, in that it has lower expression of GLUT4, an underdeveloped or nonexistent t-tubule network, and a reduced or nonexistent response to insulin. Thus, experiments carried out in cultured muscle cell systems might give misleading results on how GLUT4 translocation and the signalling involved takes place. To address this problem, a confocal imaging technique has been developed that allows delineation of the spartial and spatial distribution of GFP-tagged GLUT4 (GLUT4-GFP) translocation in living muscle fibers in situ in anesthetized mice. The effects of stimuli with insulin or in situ muscle contractions in fully differentiated muscle fibers can now be studied before, during, and after applying stimuli. Initial analysis of insulin-stimulated GLUT4-GFP translocation showed a delay in maximal translocation between the sarcolemma and t-tubules. Corresponding to the delay, we found that fluorescent tagged insulin reaches the sarcolemma first and then, with a delay, diffuses into the t-tubule system, enabling interaction with local insulin receptors and, in turn, triggering local insulin signalling and local GLUT4 translocation. In parallel, we showed that the majority of GLUT4 depot vesicles do not move long distances but are depleted locally in the sarcolemma or t-tubule regions. Analysis of GLUT4 translocation in insulin-resistant muscle showed that, primarily, GLUT4 recruitment in the t-tubule region is affected. We have now analysed the kinetics of contraction-mediated GLUT4 translocation and reinternalization, as well as dilineated some of the key signalling points involved in these processes.
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Affiliation(s)
- Hans P.M.M. Lauritzen
- Research Division, Joslin Diabetes Center and Harvard Medical School, One Joslin Place, Room 525, Boston, MA 02215, USA (e-mail: )
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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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