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Masson SWC, Madsen S, Cooke KC, Potter M, Vegas AD, Carroll L, Thillainadesan S, Cutler HB, Walder KR, Cooney GJ, Morahan G, Stöckli J, James DE. Leveraging genetic diversity to identify small molecules that reverse mouse skeletal muscle insulin resistance. eLife 2023; 12:RP86961. [PMID: 37494090 PMCID: PMC10371229 DOI: 10.7554/elife.86961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023] Open
Abstract
Systems genetics has begun to tackle the complexity of insulin resistance by capitalising on computational advances to study high-diversity populations. 'Diversity Outbred in Australia (DOz)' is a population of genetically unique mice with profound metabolic heterogeneity. We leveraged this variance to explore skeletal muscle's contribution to whole-body insulin action through metabolic phenotyping and skeletal muscle proteomics of 215 DOz mice. Linear modelling identified 553 proteins that associated with whole-body insulin sensitivity (Matsuda Index) including regulators of endocytosis and muscle proteostasis. To enrich for causality, we refined this network by focusing on negatively associated, genetically regulated proteins, resulting in a 76-protein fingerprint of insulin resistance. We sought to perturb this network and restore insulin action with small molecules by integrating the Broad Institute Connectivity Map platform and in vitro assays of insulin action using the Prestwick chemical library. These complementary approaches identified the antibiotic thiostrepton as an insulin resistance reversal agent. Subsequent validation in ex vivo insulin-resistant mouse muscle and palmitate-induced insulin-resistant myotubes demonstrated potent insulin action restoration, potentially via upregulation of glycolysis. This work demonstrates the value of a drug-centric framework to validate systems-level analysis by identifying potential therapeutics for insulin resistance.
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Affiliation(s)
- Stewart W C Masson
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Søren Madsen
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Kristen C Cooke
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Meg Potter
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Alexis Diaz Vegas
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Luke Carroll
- Australian Proteome Analysis Facility, Macquarie University, Macquarie Park, Australia
| | - Senthil Thillainadesan
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Harry B Cutler
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Ken R Walder
- School of Medicine, Deakin University, Geelong, Australia
| | - Gregory J Cooney
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - Grant Morahan
- Centre for Diabetes Research, Harry Perkins Institute of Medical Research, Murdoch, Australia
| | - Jacqueline Stöckli
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
| | - David E James
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Camperdown, Australia
- School of Medical Sciences University of Sydney, Sydney, Australia
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2
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Gilleron J, Zeigerer A. Endosomal trafficking in metabolic homeostasis and diseases. Nat Rev Endocrinol 2023; 19:28-45. [PMID: 36216881 DOI: 10.1038/s41574-022-00737-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/09/2022] [Indexed: 12/14/2022]
Abstract
The global prevalences of obesity and type 2 diabetes mellitus have reached epidemic status, presenting a heavy burden on society. It is therefore essential to find novel mechanisms and targets that could be utilized in potential treatment strategies and, as such, intracellular membrane trafficking has re-emerged as a regulatory tool for controlling metabolic homeostasis. Membrane trafficking is an essential physiological process that is responsible for the sorting and distribution of signalling receptors, membrane transporters and hormones or other ligands between different intracellular compartments and the plasma membrane. Dysregulation of intracellular transport is associated with many human diseases, including cancer, neurodegeneration, immune deficiencies and metabolic diseases, such as type 2 diabetes mellitus and its associated complications. This Review focuses on the latest advances on the role of endosomal membrane trafficking in metabolic physiology and pathology in vivo, highlighting the importance of this research field in targeting metabolic diseases.
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Affiliation(s)
- Jerome Gilleron
- Université Côte d'Azur, Institut National de la Santé et de la Recherche Médicale (Inserm), UMR1065 C3M, Team Cellular and Molecular Pathophysiology of Obesity, Nice, France.
| | - Anja Zeigerer
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
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3
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Fazakerley DJ, Koumanov F, Holman GD. GLUT4 On the move. Biochem J 2022; 479:445-462. [PMID: 35147164 PMCID: PMC8883492 DOI: 10.1042/bcj20210073] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 01/11/2022] [Accepted: 01/14/2022] [Indexed: 12/16/2022]
Abstract
Insulin rapidly stimulates GLUT4 translocation and glucose transport in fat and muscle cells. Signals from the occupied insulin receptor are translated into downstream signalling changes in serine/threonine kinases within timescales of seconds, and this is followed by delivery and accumulation of the glucose transporter GLUT4 at the plasma membrane. Kinetic studies have led to realisation that there are distinct phases of this stimulation by insulin. There is a rapid initial burst of GLUT4 delivered to the cell surface from a subcellular reservoir compartment and this is followed by a steady-state level of continuing stimulation in which GLUT4 recycles through a large itinerary of subcellular locations. Here, we provide an overview of the phases of insulin stimulation of GLUT4 translocation and the molecules that are currently considered to activate these trafficking steps. Furthermore, we suggest how use of new experimental approaches together with phospho-proteomic data may help to further identify mechanisms for activation of these trafficking processes.
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Affiliation(s)
- Daniel J Fazakerley
- Metabolic Research Laboratories, Wellcome-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, U.K
| | - Francoise Koumanov
- Department for Health, Centre for Nutrition, Exercise, and Metabolism, University of Bath, Bath, Somerset BA2 7AY, U.K
| | - Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, Bath, Somerset BA2 7AY, U.K
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4
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McNay EC, Pearson-Leary J. GluT4: A central player in hippocampal memory and brain insulin resistance. Exp Neurol 2020; 323:113076. [PMID: 31614121 PMCID: PMC6936336 DOI: 10.1016/j.expneurol.2019.113076] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/19/2019] [Accepted: 10/01/2019] [Indexed: 12/24/2022]
Abstract
Insulin is now well-established as playing multiple roles within the brain, and specifically as regulating hippocampal cognitive processes and metabolism. Impairments to insulin signaling, such as those seen in type 2 diabetes and Alzheimer's disease, are associated with brain hypometabolism and cognitive impairment, but the mechanisms of insulin's central effects are not determined. Several lines of research converge to suggest that the insulin-responsive glucose transporter GluT4 plays a central role in hippocampal memory processes, and that reduced activation of this transporter may underpin the cognitive impairments seen as a consequence of insulin resistance.
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Affiliation(s)
- Ewan C McNay
- Behavioral Neuroscience, University at Albany, Albany, NY, USA.
| | - Jiah Pearson-Leary
- Department of Anesthesiology, Abramson Research Center, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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5
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Novel Roles for the Insulin-Regulated Glucose Transporter-4 in Hippocampally Dependent Memory. J Neurosci 2017; 36:11851-11864. [PMID: 27881773 DOI: 10.1523/jneurosci.1700-16.2016] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/15/2016] [Accepted: 09/20/2016] [Indexed: 11/21/2022] Open
Abstract
The insulin-regulated glucose transporter-4 (GluT4) is critical for insulin- and contractile-mediated glucose uptake in skeletal muscle. GluT4 is also expressed in some hippocampal neurons, but its functional role in the brain is unclear. Several established molecular modulators of memory processing regulate hippocampal GluT4 trafficking and hippocampal memory formation is limited by both glucose metabolism and insulin signaling. Therefore, we hypothesized that hippocampal GluT4 might be involved in memory processes. Here, we show that, in male rats, hippocampal GluT4 translocates to the plasma membrane after memory training and that acute, selective intrahippocampal inhibition of GluT4-mediated glucose transport impaired memory acquisition, but not memory retrieval. Other studies have shown that prolonged systemic GluT4 blockade causes insulin resistance. Unexpectedly, we found that prolonged hippocampal blockade of glucose transport through GluT4-upregulated markers of hippocampal insulin signaling prevented task-associated depletion of hippocampal glucose and enhanced both working and short-term memory while also impairing long-term memory. These effects were accompanied by increased expression of hippocampal AMPA GluR1 subunits and the neuronal GluT3, but decreased expression of hippocampal brain-derived neurotrophic factor, consistent with impaired ability to form long-term memories. Our findings are the first to show the cognitive impact of brain GluT4 modulation. They identify GluT4 as a key regulator of hippocampal memory processing and also suggest differential regulation of GluT4 in the hippocampus from that in peripheral tissues. SIGNIFICANCE STATEMENT The role of insulin-regulated glucose transporter-4 (GluT4) in the brain is unclear. In the current study, we demonstrate that GluT4 is a critical component of hippocampal memory processes. Memory training increased hippocampal GluT4 translocation and memory acquisition was impaired by GluT4 blockade. Unexpectedly, whereas long-term inhibition of GluT4 impaired long-term memory, short-term memory was enhanced. These data further our understanding of the molecular mechanisms of memory and have particular significance for type 2 diabetes (in which GluT4 activity in the periphery is impaired) and Alzheimer's disease (which is linked to impaired brain insulin signaling and for which type 2 diabetes is a key risk factor). Both diseases cause marked impairment of hippocampal memory linked to hippocampal hypometabolism, suggesting the possibility that brain GluT4 dysregulation may be one cause of cognitive impairment in these disease states.
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Nishina A, Itagaki M, Suzuki Y, Koketsu M, Ninomiya M, Sato D, Suzuki T, Hayakawa S, Kuroda M, Kimura H. Effects of Flavonoids and Triterpene Analogues from Leaves of Eleutherococcus sieboldianus (Makino) Koidz. 'Himeukogi' in 3T3-L1 Preadipocytes. Molecules 2017; 22:molecules22040671. [PMID: 28441735 PMCID: PMC6154646 DOI: 10.3390/molecules22040671] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/16/2017] [Accepted: 04/19/2017] [Indexed: 12/28/2022] Open
Abstract
Eleutherococcus sieboldianus (Makino) Koidz. is a local product from the area in and around Yonezawa City in Yamagata Prefecture, Japan. It has been used as a medicinal plant for a long time. We isolated and identified four types of flavonoid glycosides [astragalin (1), isoquercetin (2), rhamnocitrin 3-O-glucoside (3), and nicotiflorin (4)], a triterpene [methyl hederagenin (5)], and three types of triterpene glycosides [δ-hederin (6), echinocystic acid 3-O-arabinoside (7), and cauloside B (8)] from the methanol extract of E. sieboldianus, which regulates lipid accumulation in 3T3-L1 preadipocytes. Among the compounds isolated, 2 and 8 up- and down-regulated lipid accumulation and insulin induced adipocyte differentiation in 3T3-L1 preadipocytes. Compound 2 induced up-regulation of lipid accumulation and decreased adipocyte size, while 8 down-regulated lipid accumulations without decreasing cell size. Additionally, 2 increased adipogenic proteins [peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and fatty-acid-binding protein 4 (FABP4)]. In contrast, 8 decreased the levels of all adipogenic proteins and glucose transporter type 4 (GLUT4), but increased adiponectin.
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Affiliation(s)
- Atsuyoshi Nishina
- College of Science and Technology, Nihon University, 1-5-1 Kandasurugadai, Chiyoda, Tokyo 101-0062, Japan.
| | - Masaya Itagaki
- College of Science and Technology, Nihon University, 1-5-1 Kandasurugadai, Chiyoda, Tokyo 101-0062, Japan.
| | - Yuusuke Suzuki
- College of Science and Technology, Nihon University, 1-5-1 Kandasurugadai, Chiyoda, Tokyo 101-0062, Japan.
| | - Mamoru Koketsu
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
| | - Masayuki Ninomiya
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
| | - Daisuke Sato
- Department of Biomedical Information Engineering, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan.
| | - Takashi Suzuki
- School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba 274-8555, Japan.
| | - Satoshi Hayakawa
- Department of Pathology and Microbiology ,School of Medicine, Nihon University, 30-1 Ohotaniguchi-kamicho, Itabashi, Tokyo 173-8610, Japan.
| | - Makoto Kuroda
- National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
| | - Hirokazu Kimura
- National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
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Nishina A, Ukiya M, Fukatsu M, Koketsu M, Ninomiya M, Sato D, Yamamoto J, Kobayashi-Hattori K, Okubo T, Tokuoka H, Kimura H. Effects of Various 5,7-Dihydroxyflavone Analogs on Adipogenesis in 3T3-L1 Cells. Biol Pharm Bull 2016; 38:1794-800. [PMID: 26521830 DOI: 10.1248/bpb.b15-00489] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We studied the effects of twelve 5,7-dihydroxyflavone analogs on adipogenesis in 3T3-L1 cells. Among the compounds, luteolin, diosmetin, and chrysoeriol partly inhibited adipogenesis by blocking the accumulation of triacylglycerol in the cells. Conversely, tricetin facilitated triacylglycerol accumulation in the cells. The induction of lipogenesis or lipolysis may depend on the number and bonding position of hydroxyl or methoxy groups on the B ring of 5,7-dihydroxyflavone. The mRNA expression levels of adipogenic and lipogenic genes were suppressed by luteolin treatment in the cells, while the mRNA levels of lipolytic genes were not affected. However, the expression levels of the adipogenic, lipogenic, and lipolytic genes, except for adipocyte protein 2 (aP2), were not affected by the addition of tricetin. Moreover, luteolin suppressed glucose transporter type 4 (GLUT4) gene and protein levels. These results indicate that luteolin decreased triacylglycerol levels in 3T3-L1 cells during adipogenesis through the suppression of adipogenic/lipogenic and GLUT4 genes and GLUT4 protein.
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8
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Carrig S, Bijjiga E, Wopat MJ, Martino AT. Insulin Therapy Improves Adeno-Associated Virus Transduction of Liver and Skeletal Muscle in Mice and Cultured Cells. Hum Gene Ther 2016; 27:892-905. [PMID: 27358030 DOI: 10.1089/hum.2016.073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Adeno-associated virus (AAV) gene transfer is a promising treatment for genetic abnormalities. Optimal AAV vectors are showing success in clinical trials. Gene transfer to skeletal muscle and liver is being explored as a potential therapy for some conditions, that is, α1-antitrypsin (AAT) disorder and hemophilia B. Exploring approaches that enhance transduction of liver and skeletal muscle, using these vectors, is beneficial for gene therapy. Regulating hormones as an approach to improve AAV transduction is largely unexplored. In this study we tested whether insulin therapy improves liver and skeletal muscle gene transfer. In vitro studies demonstrated that the temporary coadministration (2, 8, and 24 hr) of insulin significantly improves AAV2-CMV-LacZ transduction of cultured liver cells and differentiated myofibers, but not of lung cells. In addition, there was a dose response related to this improved transduction. Interestingly, when insulin was not coadministered with the virus but given 24 hr afterward, there was no increase in the transgene product. Insulin receptor gene (INSR) expression levels were increased 5- to 13-fold in cultured liver cells and differentiated myofibers when compared with lung cells. Similar INSR gene expression profiles occurred in mouse tissues. Insulin therapy was performed in mice, using a subcutaneously implanted insulin pellet or a high-carbohydrate diet. Insulin treatment began just before intramuscular delivery of AAV1-CMV-schFIX or liver-directed delivery of AAV8-CMV-schFIX and continued for 28 days. Both insulin augmentation therapies improved skeletal muscle- and liver-directed gene transduction in mice as seen by a 3.0- to 4.5-fold increase in human factor IX (hFIX) levels. The improvement was observed even after the insulin therapy ended. Monitoring insulin showed that insulin levels increased during the brief period of rAAV delivery and during the entire insulin augmentation period (28 days). This study demonstrates that AAV transduction of liver or skeletal muscle can be improved by insulin therapy.
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Affiliation(s)
- Sean Carrig
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University , Queens, New York
| | - Enoch Bijjiga
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University , Queens, New York
| | - Mitchell J Wopat
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University , Queens, New York
| | - Ashley T Martino
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University , Queens, New York
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9
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Anti-diabetic effect of 3-hydroxy-2-naphthoic acid, an endoplasmic reticulum stress-reducing chemical chaperone. Eur J Pharmacol 2016; 779:157-67. [PMID: 26983645 DOI: 10.1016/j.ejphar.2016.03.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/11/2016] [Accepted: 03/11/2016] [Indexed: 01/22/2023]
Abstract
Lots of experimental and clinical evidences indicate that chronic exposure to saturated fatty acids and high level of glucose is implicated in insulin resistance, beta cell failure and ultimately type 2 diabetes. In this study, we set up cell-based experimental conditions to induce endoplasmic reticulum (ER) stress and insulin resistance using high concentration of palmitate (PA). Hydroxynaphthoic acids (HNAs) were formerly identified as novel chemical chaperones to resolve ER stress induced by tunicamycin. In this study, we found the compounds have the same suppressive effect on PA-induced ER stress in HepG2 cells. The representing compound, 3-HNA reduced PA-induced phosphorylation of JNK, IKKβ and IRS1 (S307) and restored insulin signaling cascade which involves insulin receptor β, IRS1 and Akt. The insulin sensitizing effect of 3-HNA was confirmed in 3T3-L1 adipocytes, where the compound augmented insulin signaling and glucose transporter 4 (GLUT4) membrane translocation. 3-HNA also protected the pancreatic beta cells from PA-induced apoptosis by reducing ER stress. Upon 3-HNA treatment to ob/ob mice at 150mg/kg/day dosage, the diabetic parameters including glucose tolerance and systemic insulin sensitivity were significantly improved. Postmortem examination showed that 3-HNA markedly reduced ER stress and insulin resistance in the liver tissues and it sensitized insulin signaling in the liver and the skeletal muscle. Our results demonstrated that 3-HNA can sensitize insulin signaling by coping with lipotoxicity-induced ER stress as a chemical chaperone and suggested it holds therapeutic potential for insulin resistance and type 2 diabetes.
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Mitsuhashi K, Senmaru T, Fukuda T, Yamazaki M, Shinomiya K, Ueno M, Kinoshita S, Kitawaki J, Katsuyama M, Tsujikawa M, Obayashi H, Nakamura N, Fukui M. Testosterone stimulates glucose uptake and GLUT4 translocation through LKB1/AMPK signaling in 3T3-L1 adipocytes. Endocrine 2016; 51:174-84. [PMID: 26100787 DOI: 10.1007/s12020-015-0666-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/12/2015] [Indexed: 10/23/2022]
Abstract
Decreases in serum testosterone concentrations in aging men are associated with metabolic disorders. Testosterone has been reported to increase GLUT4-dependent glucose uptake in skeletal muscle cells and cardiomyocytes. However, studies on glucose uptake occurring in response to testosterone stimulation in adipocytes are currently not available. This study was designed to determine the effects of testosterone on glucose uptake in adipocytes. Glucose uptake was assessed with 2-[(3)H] deoxyglucose in 3T3-L1 adipocytes. GLUT4 translocation was evaluated in plasma membrane (PM) sheets and PM fractions by immunofluorescence and immunoblotting, respectively. Activation of GLUT4 translocation-related protein kinases, including Akt, AMPK, LKB1, CaMKI, CaMKII, and Cbl was followed by immunoblotting. Expression levels of androgen receptor (AR) mRNA and AR translocation to the PM were assessed by real-time RT-PCR and immunoblotting, respectively. The results showed that both high-dose (100 nM) testosterone and testosterone-BSA increased glucose uptake and GLUT4 translocation to the PM, independently of the intracellular AR. Testosterone and testosterone-BSA stimulated the phosphorylation of AMPK, LKB1, and CaMKII. The knockdown of LKB1 by siRNA attenuated testosterone- and testosterone-BSA-stimulated AMPK phosphorylation and glucose uptake. These results indicate that high-dose testosterone and testosterone-BSA increase GLUT4-dependent glucose uptake in 3T3-L1 adipocytes by inducing the LKB1/AMPK signaling pathway.
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Affiliation(s)
- Kazuteru Mitsuhashi
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
| | - Takafumi Senmaru
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan.
| | - Takuya Fukuda
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
| | - Masahiro Yamazaki
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
| | - Katsuhiko Shinomiya
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Morio Ueno
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Shigeru Kinoshita
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Jo Kitawaki
- Department of Obstetrics and Gynecology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Masato Katsuyama
- Radioisotope Center, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | | | | | - Naoto Nakamura
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
| | - Michiaki Fukui
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
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11
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Ohta M, Fujinami A, Kobayashi N, Amano A, Ishigami A, Tokuda H, Suzuki N, Ito F, Mori T, Sawada M, Iwasa K, Kitawaki J, Ohnishi K, Tsujikawa M, Obayashi H. Two chalcones, 4-hydroxyderricin and xanthoangelol, stimulate GLUT4-dependent glucose uptake through the LKB1/AMP-activated protein kinase signaling pathway in 3T3-L1 adipocytes. Nutr Res 2015; 35:618-25. [PMID: 26077869 DOI: 10.1016/j.nutres.2015.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/15/2015] [Accepted: 05/27/2015] [Indexed: 01/01/2023]
Abstract
4-Hydroxyderricin (4HD) and xanthoangelol (XAG) are major components of n-hexane/ethyl acetate (5:1) extract of the yellow-colored stem juice of Angelica keiskei. 4-Hydroxyderricin and XAG have been reported to increase glucose transporter 4 (GLUT4)-dependent glucose uptake in 3T3-L1 adipocytes, but the detailed mechanism of this phenomenon remains unknown. This present study was aimed at clarifying the detailed mechanism by which 4HD and XAG increase GLUT4-dependent glucose uptake in 3T3-L1 adipocytes. Both 4HD and XAG increased glucose uptake and GLUT4 translocation to the plasma membrane. 4-Hydroxyderricin and XAG also stimulated the phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK) and its downstream target acetyl-CoA carboxylase. In addition, phosphorylation of liver kinase B1 (LKB1), which acts upstream of AMPK, was also increased by 4HD and XAG treatment. Small interfering RNA knockdown of LKB1 attenuated 4HD- and XAG-stimulated AMPK phosphorylation and suppressed glucose uptake. These findings demonstrate that 4HD and XAG can increase GLUT4-dependent glucose uptake through the LKB1/AMPK signaling pathway in 3T3-L1 adipocytes.
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Affiliation(s)
- Mitsuhiro Ohta
- Department of Medical Biochemistry, Kobe Pharmaceutical University, Kobe, 658-8558, Japan.
| | - Aya Fujinami
- Department of Medical Biochemistry, Kobe Pharmaceutical University, Kobe, 658-8558, Japan
| | - Norihiro Kobayashi
- Department of Bioanalytical Chemistry, Kobe Pharmaceutical University, Kobe, 658-8558, Japan
| | - Akiko Amano
- Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Akihito Ishigami
- Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Harukuni Tokuda
- Department of Complementary and Alternative Medicine, Clinical R&D, Kanazawa University of Graduate School of Medical Science, Kanazawa, 920-8640, Japan
| | - Nobutaka Suzuki
- Department of Complementary and Alternative Medicine, Clinical R&D, Kanazawa University of Graduate School of Medical Science, Kanazawa, 920-8640, Japan
| | - Fumitake Ito
- Department of Obstetrics and Gynecology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Taisuke Mori
- Department of Obstetrics and Gynecology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Morio Sawada
- Department of Obstetrics and Gynecology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Koichi Iwasa
- Department of Obstetrics and Gynecology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Jo Kitawaki
- Department of Obstetrics and Gynecology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | | | - Muneo Tsujikawa
- Institute of Bio-Response Informatics, Kyoto, 602-8566, Japan
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12
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Yao Y, Tsirka SE. Mouse monocyte chemoattractant protein 1 (MCP1) functions as a monomer. Int J Biochem Cell Biol 2014; 55:51-9. [PMID: 25130440 DOI: 10.1016/j.biocel.2014.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/13/2014] [Accepted: 08/04/2014] [Indexed: 11/28/2022]
Abstract
Monocyte chemoattractant protein 1 (MCP1) is an important chemoattractant for microglia. Rodent MCP1 carries a heavily glycosylated C-terminus, which has been predicted to increase local MCP1 concentration, promote MCP1 dimerization/oligomerization, and facilitate receptor engagement. Previous studies have shown that MCP1 mutant lacking the glycosylated C-terminus cannot dimerize/oligomerize, but has higher chemotactic potency than the wild-type (full-length) MCP1, suggesting that rodent MCP1 may function as a monomer. Although many groups support this hypothesis, there is no direct evidence on whether rodent MCP1 dimer is functional. In this paper, using forced recombinant dimeric MCP1 proteins we show that mouse MCP1 dimer is unable to activate Rac1, promote protrusion of lamellipodia, or induce microglial migration, although it can bind to CCR2 and mediate its internalization. These results support the idea that signaling events mediated by MCP1 require the presence of the monomeric form of this chemokine.
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Affiliation(s)
- Yao Yao
- Department of Pharmacology, Stony Brook University, Stony Brook, NY 11794-8651, USA.
| | - Stella E Tsirka
- Department of Pharmacology, Stony Brook University, Stony Brook, NY 11794-8651, USA
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13
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A Method for the Simultaneous Determination of 3T3-L1 Adipocyte Metabolites by Liquid Chromatography/Mass Spectrometry Using [13C]-stable Isotopes. Biosci Biotechnol Biochem 2014; 75:1485-9. [DOI: 10.1271/bbb.110192] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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14
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Mohan S S, Perry JJP, Poulose N, Nair BG, Anilkumar G. Homology modeling of GLUT4, an insulin regulated facilitated glucose transporter and docking studies with ATP and its inhibitors. J Biomol Struct Dyn 2013; 26:455-64. [PMID: 19108584 DOI: 10.1080/07391102.2009.10507260] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
GLUT4 is a 12 transmembrane (TM) protein belonging to the Class I facilitated glucose transporter family that transports glucose into the cells in an insulin regulated manner. GLUT4 plays a key role in the maintenance of blood glucose homeostasis and inhibition of glucose transporter activity may lead to insulin resistance, hallmark of type 2 diabetes. No crystal structure data is available for any members of the facilitated glucose transporter family. Here, in this paper, we have generated a homology model of GLUT4 based on experimental data available on GLUT1, a Class I facilitated glucose transporter and the crystal structure data obtained from the Glycerol 3-phosphate transporter. The model identified regions in GLUT4 that form a channel for the transport of glucose along with the substrate interacting residues. Docking and electrostatic potential data analysis of GLUT4 model has mapped an ATP binding region close to the binding site of cytochalasin B and genistein, two GLUT4 inhibitors, and this may explain the mechanism by which these inhibitors could potentially affect the GLUT4 function.
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Affiliation(s)
- Suma Mohan S
- School of Biotechnology, Amrita University, Kollam, Kerala 690525, India
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15
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Olson AL. Regulation of GLUT4 and Insulin-Dependent Glucose Flux. ISRN MOLECULAR BIOLOGY 2012; 2012:856987. [PMID: 27335671 PMCID: PMC4890881 DOI: 10.5402/2012/856987] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 09/24/2012] [Indexed: 12/21/2022]
Abstract
GLUT4 has long been known to be an insulin responsive glucose transporter. Regulation of GLUT4 has been a major focus of research on the cause and prevention of type 2 diabetes. Understanding how insulin signaling alters the intracellular trafficking of GLUT4 as well as understanding the fate of glucose transported into the cell by GLUT4 will be critically important for seeking solutions to the current rise in diabetes and metabolic disease.
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Affiliation(s)
- Ann Louise Olson
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, P.O. Box 26901, BMSB 964, Oklahoma City, OK 73190, USA
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16
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Wang H, Wang AX, Barrett EJ. Insulin-induced endothelial cell cortical actin filament remodeling: a requirement for trans-endothelial insulin transport. Mol Endocrinol 2012; 26:1327-38. [PMID: 22734037 DOI: 10.1210/me.2012-1003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Insulin's trans-endothelial transport (TET) is critical for its metabolic action on muscle and involves trafficking of insulin bound to its receptor (or at high insulin concentrations, the IGF-I receptor) via caveolae. However, whether caveolae-mediated insulin TET involves actin cytoskeleton organization is unknown. Here we address whether insulin regulates actin filament organization in bovine aortic endothelial cells (bAEC) and whether this affects insulin uptake and TET. We found that insulin induced extensive cortical actin filament remodeling within 5 min. This remodeling was inhibited not only by disruption of actin microfilament organization but also by inhibition of phosphatidylinositol 3-kinase (PI3K) or by disruption of lipid rafts using respective specific inhibitors. Knockdown of either caveolin-1 or Akt using specific small interfering RNA also eliminated the insulin-induced cortical actin filament remodeling. Blocking either actin microfilament organization or PI3K pathway signaling inhibited both insulin uptake and TET. Disruption of actin microfilament organization also reduced the caveolin-1, insulin receptor, and IGF-I receptor located at the plasma membrane. Exposing bAEC for 6 h to either TNFα or IL-6 blocked insulin-induced cortical actin remodeling. Extended exposure (24 h) also inhibited actin expression at both mRNA and protein levels. We conclude that insulin-induced cortical actin filament remodeling in bAEC is required for insulin's TET in a PI3K/Akt and plasma membrane lipid rafts/caveolae-dependent fashion, and proinflammatory cytokines TNFα and IL-6 block this process.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
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17
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Iwashita M, Sakoda H, Kushiyama A, Fujishiro M, Ohno H, Nakatsu Y, Fukushima T, Kumamoto S, Tsuchiya Y, Kikuchi T, Kurihara H, Akazawa H, Komuro I, Kamata H, Nishimura F, Asano T. Valsartan, independently of AT1 receptor or PPARγ, suppresses LPS-induced macrophage activation and improves insulin resistance in cocultured adipocytes. Am J Physiol Endocrinol Metab 2012; 302:E286-96. [PMID: 22045314 DOI: 10.1152/ajpendo.00324.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Macrophages are integrated into adipose tissues and interact with adipocytes in obese subjects, thereby exacerbating adipose insulin resistance. This study aimed to elucidate the molecular mechanism underlying the insulin-sensitizing effect of the angiotensin II receptor blocker (ARB) valsartan, as demonstrated in clinical studies. Insulin signaling, i.e., insulin receptor substrate-1 and Akt phosphorylations, in 3T3-L1 adipocytes was impaired markedly by treatment with tumor necrosis factor-α (TNFα) or in the culture medium of lipopolysaccharide (LPS)-stimulated RAW 264.7 murine macrophages, and valsartan had no effects on these impairments. However, in contrast, when cocultured with RAW 264.7 cells using a transwell system, the LPS-induced insulin signaling impairment in 3T3-L1 adipocytes showed almost complete normalization with coaddition of valsartan. Furthermore, valsartan strongly suppressed LPS-induced productions of cytokines such as interleukin (IL)-1β, IL-6, and TNFα with nuclear factor-κB activation and c-Jun NH(2)-terminal kinase phosphorylation in RAW 264.7 and primary murine macrophages. Very interestingly, this effect of valsartan was also observed in THP-1 cells treated with angiotensin II type 1 (AT1) siRNA or a peroxisome proliferator-activated receptor-γ (PPARγ) antagonist as well as macrophages from AT1a receptor-knockout mice. We conclude that valsartan suppresses the inflammatory response of macrophages, albeit not via PPARγ or the AT1a receptor. This suppression appears to secondarily improve adipose insulin resistance.
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MESH Headings
- 3T3-L1 Cells
- Adipocytes, White/drug effects
- Adipocytes, White/immunology
- Adipocytes, White/metabolism
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Anti-Inflammatory Agents, Non-Steroidal/pharmacology
- Cell Line
- Cells, Cultured
- Coculture Techniques
- Humans
- Insulin Resistance
- Macrophage Activation/drug effects
- Macrophages/drug effects
- Macrophages/immunology
- Macrophages/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- PPAR gamma/antagonists & inhibitors
- PPAR gamma/metabolism
- RNA Interference
- RNA, Small Interfering
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Tetrazoles/pharmacology
- Valine/analogs & derivatives
- Valine/pharmacology
- Valsartan
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Affiliation(s)
- Misaki Iwashita
- Department of Biomedical Chemistry, Division of Molecular Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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18
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Strålfors P. Caveolins and Caveolae, Roles in Insulin Signalling and Diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 729:111-26. [DOI: 10.1007/978-1-4614-1222-9_8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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19
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Basic fibroblast growth factor regulates glucose metabolism through glucose transporter 1 induced by hypoxia-inducible factor-1α in adipocytes. Int J Biochem Cell Biol 2011; 43:1602-11. [DOI: 10.1016/j.biocel.2011.07.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/15/2011] [Accepted: 07/20/2011] [Indexed: 02/06/2023]
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20
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Lin Y, Sun Z. Thyroid hormone promotes insulin-induced glucose uptake by enhancing Akt phosphorylation and VAMP2 translocation in 3T3-L1 adipocytes. J Cell Physiol 2011; 226:2625-32. [PMID: 21792921 DOI: 10.1002/jcp.22613] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The purpose of this study was to test a hypothesis that T3 promotes glucose uptake via enhancing insulin-induced Akt phosphorylation and VAMP2 translocation in 3T3-L1 adipocytes. T3 significantly enhanced insulin-induced phosphorylation of Akt, cytoplasma to cell membrane translocations of vesicle-associated membrane protein 2 (VAMP2) and glucose transporter 4 (GLUT4), and glucose uptake in adipocytes. Akt inhibitor X abolished the promoting effects of T3, suggesting that Akt activation is essential for T3 to enhance these insulin-induced events in adipocytes. Knockdown of VAMP2 using siRNA abrogated the effects of T3 on insulin-induced GLUT4 translocation and glucose uptake, suggesting that VAMP2 is an important mediator of these processes. These data suggest that T3 may promote glucose uptake via enhancing insulin-induced phosphorylation of Akt and subsequent translocations of VAMP2 and GLUT4 in 3T3-L1 adipocytes. Akt phosphorylation is necessary for the promoting effects of T3 on insulin-stimulated VAMP2 translocation. Further, VAMP2 is essential for T3 to increase insulin-stimulated translocation of GLUT4 and subsequent uptake of glucose in adipocytes.
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Affiliation(s)
- Yi Lin
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73126-0901, USA
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21
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STAGSTED JAN. Journey beyond immunology. Regulation of receptor internalization by major histocompatibility complex class I (MHC-I) and effect of peptides derived from MHC-I. APMIS 2011. [DOI: 10.1111/j.1600-0463.1998.tb05657.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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22
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Zhang Q, Zhang Y, Feng H, Guo R, Jin L, Wan R, Wang L, Chen C, Li S. High density lipoprotein (HDL) promotes glucose uptake in adipocytes and glycogen synthesis in muscle cells. PLoS One 2011; 6:e23556. [PMID: 21886796 PMCID: PMC3158770 DOI: 10.1371/journal.pone.0023556] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 07/20/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND High density lipoprotein (HDL) was reported to decrease plasma glucose and promote insulin secretion in type 2 diabetes patients. This investigation was designed to determine the effects and mechanisms of HDL on glucose uptake in adipocytes and glycogen synthesis in muscle cells. METHODS AND RESULTS Actions of HDL on glucose uptake and GLUT4 translocation were assessed with 1-[(3)H]-2-deoxyglucose and plasma membrane lawn, respectively, in 3T3-L1 adipocytes. Glycogen analysis was performed with amyloglucosidase and glucose oxidase-peroxidase methods in normal and palmitate-treated L6 cells. Small interfering RNA was used to observe role of scavenger receptor type I (SR-BI) in glucose uptake of HDL. Corresponding signaling molecules were detected by immunoblotting. HDL stimulated glucose uptake in a time- and concentration-dependent manner in 3T3-L1 adipocytes. GLUT4 translocation was significantly increased by HDL. Glycogen deposition got enhanced in L6 muscle cells paralleling with elevated glycogen synthase kinase3 (GSK3) phosphorylation. Meanwhile, increased phosphorylations of Akt-Ser473 and AMP activated protein kinase (AMPK) α were detected in 3T3-L1 adipocytes. Glucose uptake and Akt-Ser473 activation but not AMPK-α were diminished in SR-BI knock-down 3T3-L1 cells. CONCLUSIONS HDL stimulates glucose uptake in 3T3-L1 adipocytes through enhancing GLUT4 translocation by mechanisms involving PI3K/Akt via SR-BI and AMPK signaling pathways, and increases glycogen deposition in L6 muscle cells through promoting GSK3 phosphorylation.
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Affiliation(s)
- Qichun Zhang
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, People's Republic of China
| | - Yun Zhang
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Haihua Feng
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Rui Guo
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Lai Jin
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Rong Wan
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Lina Wang
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Cheng Chen
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
| | - Shengnan Li
- Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China
- * E-mail:
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23
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Stöckli J, Fazakerley DJ, Coster ACF, Holman GD, James DE. Muscling in on GLUT4 kinetics. Commun Integr Biol 2011; 3:260-2. [PMID: 20714409 DOI: 10.4161/cib.3.3.11457] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 02/10/2010] [Indexed: 01/14/2023] Open
Abstract
Insulin triggers glucose uptake into muscle and adipose tissue by stimulating the translocation of the glucose transporter glut4 from intracellular vesicles to the plasma membrane (pm). insulin leads to a rapid increase in glut4 at the pm from approximately 5% to 40-50%. this effect is time and dose-dependent, reaching a new steady state after 30 min of insulin stimulation. previous kinetic analyses in adipocytes has revealed that this is regulated by two mechanisms-increasing the amount of glut4 in the endosomal recycling system and increasing the exocytosis rate constant. fazakerley et al.1 focuses on GLUT4 kinetics in the L6 skeletal muscle cell line. Despite displaying a similar redistribution of GLUT4 to the cell surface with insulin to that seen in adipocytes, the mechanism for this effect in L6 cells was completely different. Insulin had a modest effect to increase the amount of GLUT4 in the recycling system with the dominant effect being on reduction of the endocytosis rate constant. Similar findings were observed with AMPK agonists. These studies indicate that different cell types are capable of achieving the same cell biological endpoint but using completely distinct mechanisms.
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24
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Abstract
One of the most important metabolic actions of insulin is catalysing glucose uptake into skeletal muscle and adipose tissue. This is accomplished via activation of the phosphatidylinositol-3-kinase/Akt signalling pathway and subsequent translocation of GLUT4 from intracellular storage vesicles to the plasma membrane. As such, this represents an ideal system for studying the convergence of signal transduction and protein trafficking. The GLUT4 translocation process is complex, but can be dissected into at least four discrete trafficking steps. This raises the question as to which of these is the major regulated step in insulin-stimulated GLUT4 translocation. Numerous molecules have been reported to regulate GLUT4 trafficking. However, with the exception of TBC1D4, the molecular details of these distal signalling arms of the insulin signalling network and how they modify distinct steps of GLUT4 trafficking have not been established. We discuss the need to adopt a more global approach to expand and deepen our understanding of the molecular processes underpinning this system. Strategies that facilitate the generation of detailed models of the entire insulin signalling network will enable us to identify the critical nodes that control GLUT4 traffic and decipher emergent properties of the system that are not currently apparent.
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Affiliation(s)
- Alexander F Rowland
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, New South Wales 2010, Australia
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25
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Habtemichael EN, Brewer PD, Romenskaia I, Mastick CC. Kinetic evidence that Glut4 follows different endocytic pathways than the receptors for transferrin and alpha2-macroglobulin. J Biol Chem 2011; 286:10115-25. [PMID: 21252237 DOI: 10.1074/jbc.m111.217935] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin regulates glucose uptake through effects on the trafficking of the glucose transporter Glut4. To investigate the degree of overlap between Glut4 and the general endocytic pathways, the kinetics of trafficking of Glut4 and the receptors for transferrin (Tf) and α(2)-macroglobulin (α-2-M; LRP-1) were compared using quantitative flow cytometric assays. Insulin increased the exocytic rate constant (k(ex)) for both Glut4 and Tf. However, the k(ex) of Glut4 was 5-15 times slower than Tf in both basal and insulin-stimulated cells. The endocytic rate constant (k(en)) of Glut4 was also five times slower than Tf. Insulin did not affect the k(en) of either protein. In basal cells, the k(en) for α-2-M/LRP-1 was similar to Glut4 but 5-fold slower than Tf. Insulin increased k(en) for α-2-M/LRP-1 by 30%. In contrast, the k(ex) for LRP-1 was five times faster than Glut4 in basal cells, and insulin did not increase this rate constant. Thus, although there is overlap in the protein machineries/compartments utilized, the differences in trafficking kinetics indicate that Glut4, the Tf receptor, and LRP-1 are differentially processed both within the cell and at the plasma membrane. It has been reported that insulin decreases the k(en) of Glut4 in adipocytes. However, the effect of exocytosis on the "internalization" assays was not considered. Because it is counterintuitive, the effect of exocytosis on these assays is often overlooked in endocytosis studies. Using mathematical modeling and simulation, we show that the reported decrease in Glut4 k(en) can be entirely accounted for by the well established increase in Glut4 k(ex).
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Affiliation(s)
- Estifanos N Habtemichael
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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26
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27
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Yao Y, Tsirka SE. The C terminus of mouse monocyte chemoattractant protein 1 (MCP1) mediates MCP1 dimerization while blocking its chemotactic potency. J Biol Chem 2010; 285:31509-16. [PMID: 20682771 DOI: 10.1074/jbc.m110.124891] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The extracellular protease plasmin cleaves mouse MCP1 (monocyte chemoattractant protein 1) at lysine 104, releasing a 50-amino acid C-terminal domain. The cleavage event increases the chemotactic activity of MCP1 and, by doing so, promotes the progression of excitotoxic injury in the central nervous system in pathological settings. The mechanism through which the cleavage event enhances MCP1-mediated chemoattraction is unknown; to investigate it, we use wild-type and mutant forms of recombinant MCP1. Full-length MCP1 (FL-MCP1) is secreted by cells as a dimer or multimer. We show that a mutant truncated at the C terminus, K104Stop-MCP1, does not dimerize, revealing that the C terminus mediates the interaction. MCP1 interacts with the monocyte/microglia receptor CCR2. The interaction is critical to the function of MCP1 because CCR2(-/-) microglia do not undergo chemotaxis in response to MCP1 stimulation. We show that stimulation of microglia with FL-MCP1 or K104Stop-MCP1 triggers CCR2 internalization, whereas a mutant form unable to be cleaved at lysine 104 (K104A-MCP1) is relatively ineffective in this assay, suggesting that the C-terminal region interferes with the MCP1-CCR2 interaction. Moreover, FL-MCP1 and K104Stop-MCP1 stimulation leads to activation of Rac1, a small GTPase involved in cell migration. Conversely, MCP1-stimulated microglial migration is blocked by the Rac1 inhibitor, NSC23766, demonstrating the requirement for Rac1 effector pathways in this response. Taken together, we propose a model for MCP1 localization, activation, and function based on the initial presence and then removal of its C terminus, coupled with a requisite downstream signaling pathway from CCR2 stimulation to Rac1 activation.
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Affiliation(s)
- Yao Yao
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794-8651, USA
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28
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Stimulation of GLUT4 (glucose transporter isoform 4) storage vesicle formation by sphingolipid depletion. Biochem J 2010; 427:143-50. [PMID: 20085539 DOI: 10.1042/bj20091529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Insulin stimulates glucose transport in fat and skeletal muscle cells primarily by inducing the translocation of GLUT4 (glucose transporter isoform 4) to the PM (plasma membrane) from specialized GSVs (GLUT4 storage vesicles). Glycosphingolipids are components of membrane microdomains and are involved in insulin-regulated glucose transport. Cellular glycosphingolipids decrease during adipocyte differentiation and have been suggested to be involved in adipocyte function. In the present study, we investigated the role of glycosphingolipids in regulating GLUT4 translocation. We decreased glycosphingolipids in 3T3-L1 adipocytes using glycosphingolipid synthesis inhibitors and investigated the effects on GLUT4 translocation using immunocytochemistry, preparation of PM sheets, isolation of GSVs and FRAP (fluorescence recovery after photobleaching) of GLUT4-GFP (green fluorescent protein) in intracellular structures. Glycosphingolipids were located in endosomal vesicles in pre-adipocytes and redistributed to the PM with decreased expression at day 2 after initiation of differentiation. In fully differentiated adipocytes, depletion of glycosphingolipids dramatically accelerated insulin-stimulated GLUT4 translocation. Although insulin-induced phosphorylation of IRS (insulin receptor substrate) and Akt remained intact in glycosphingolipid-depleted cells, both in vitro budding of GLUT4 vesicles and FRAP of GLUT4-GFP on GSVs were stimulated. Glycosphingolipid depletion also enhanced the insulin-induced translocation of VAMP2 (vesicle-associated membrane protein 2), but not the transferrin receptor or cellubrevin, indicating that the effect of glycosphingolipids was specific to VAMP2-positive GSVs. Our results strongly suggest that decreasing glycosphingolipid levels promotes the formation of GSVs and, thus, GLUT4 translocation. These studies provide a mechanistic basis for recent studies showing that inhibition of glycosphingolipid synthesis improves glycaemic control and enhances insulin sensitivity in animal models of Type 2 diabetes.
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29
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Inder KL, Lau C, Loo D, Chaudhary N, Goodall A, Martin S, Jones A, van der Hoeven D, Parton RG, Hill MM, Hancock JF. Nucleophosmin and nucleolin regulate K-Ras plasma membrane interactions and MAPK signal transduction. J Biol Chem 2009; 284:28410-28419. [PMID: 19661056 PMCID: PMC2788890 DOI: 10.1074/jbc.m109.001537] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 08/06/2009] [Indexed: 01/07/2023] Open
Abstract
The spatial organization of Ras proteins into nanoclusters on the inner leaflet of the plasma membrane is essential for high fidelity signaling through the MAPK pathway. Here we identify two selective regulators of K-Ras nanoclustering from a proteomic screen for K-Ras interacting proteins. Nucleophosmin (NPM) and nucleolin are predominantly localized to the nucleolus but also have extranuclear functions. We show that a subset of NPM and nucleolin localizes to the inner leaflet of plasma membrane and forms specific complexes with K-Ras but not other Ras isoforms. Active GTP-loaded and inactive GDP-loaded K-Ras both interact with NPM, although NPM-K-Ras binding is increased by growth factor receptor activation. NPM and nucleolin both stabilize K-Ras levels on the plasma membrane, but NPM concurrently increases the clustered fraction of GTP-K-Ras. The increase in nanoclustered GTP-K-Ras in turn enhances signal gain in the MAPK pathway. In summary these results reveal novel extranucleolar functions for NPM and nucleolin as regulators of K-Ras nanocluster formation and activation of the MAPK pathway. The study also identifies a new class of K-Ras nanocluster regulator that operates independently of the structural scaffold galectin-3.
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Affiliation(s)
- Kerry L Inder
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia
| | - Chiyan Lau
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia
| | - Dorothy Loo
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia; Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane 4102, Australia
| | - Natasha Chaudhary
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia
| | - Andrew Goodall
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia
| | - Sally Martin
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia
| | - Alun Jones
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia
| | - Dharini van der Hoeven
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77030
| | - Robert G Parton
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia; Centre for Microscopy and Microanalysis, University of Queensland, Brisbane 4072, Australia
| | - Michelle M Hill
- Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia; Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane 4102, Australia.
| | - John F Hancock
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77030.
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González-Muñoz E, López-Iglesias C, Calvo M, Palacín M, Zorzano A, Camps M. Caveolin-1 loss of function accelerates glucose transporter 4 and insulin receptor degradation in 3T3-L1 adipocytes. Endocrinology 2009; 150:3493-502. [PMID: 19406948 DOI: 10.1210/en.2008-1520] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Caveolae are a specialized type of lipid rafts that are stabilized by oligomers of caveolin protein. Caveolae are particularly enriched in adipocytes. Here we analyzed the effects of caveolin-1 knockdown and caveolae ablation on adipocyte function. To this end, we obtained several multiclonal mouse 3T3-L1 cell lines with a reduced expression of caveolin-1 (95% reduction) by a small interfering RNA approach using lentiviral vectors. Control cell lines were obtained by lentiviral infection with lentiviral vectors encoding appropriate scrambled RNAs. Caveolin-1 knockdown adipocytes showed a drastic reduction in the number of caveolae (95% decrease) and cholera toxin labeling was reorganized in dynamic plasma membrane microdomains. Caveolin-1 depletion caused a specific decrease in glucose transporter 4 (GLUT4) and insulin receptor protein levels. This reduction was not the result of a generalized defect in adipocyte differentiation or altered gene expression but was explained by faster degradation of these proteins. Caveolin-1 knockdown adipocytes showed reductions in insulin-stimulated glucose transport, insulin-triggered GLUT4 recruitment to the cell surface, and insulin receptor activation. In all, our data indicate that caveolin-1 loss of function reduces maximal insulin response through lowered stability and diminished expression of insulin receptors and GLUT4. We propose that caveolin-1/caveolae control insulin action in adipose cells.
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Affiliation(s)
- Elena González-Muñoz
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Institute for Research in Biomedicine (IRB Barcelona), Serveis Cientifico-Tècnics, Universitat de Barcelona, 08028 Barcelona, Spain
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31
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Muruáis G, Lalioti V, Sandoval IV. The Cdk5 inhibitor roscovitine strongly inhibits glucose uptake in 3T3-L1 adipocytes without altering GLUT4 translocation from internal pools to the cell surface. J Cell Physiol 2009; 220:238-44. [DOI: 10.1002/jcp.21758] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Muretta JM, Mastick CC. How insulin regulates glucose transport in adipocytes. VITAMINS AND HORMONES 2009; 80:245-86. [PMID: 19251041 DOI: 10.1016/s0083-6729(08)00610-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Insulin stimulates glucose storage and metabolism by the tissues of the body, predominantly liver, muscle and fat. Storage in muscle and fat is controlled to a large extent by the rate of facilitative glucose transport across the plasma membrane of the muscle and fat cells. Insulin controls this transport. Exactly how remains debated. Work presented in this review focuses on the pathways responsible for the regulation of glucose transport by insulin. We present some historical work to show how the prevailing model for regulation of glucose transport by insulin was originally developed, then some more recent data challenging this model. We finish describing a unifying model for the control of glucose transport, and some very recent data illustrating potential molecular machinery underlying this regulation. This review is meant to give an overview of our current understanding of the regulation of glucose transport through the regulation of the trafficking of Glut4, highlighting important questions that remain to be answered. A more detailed treatment of specific aspects of this pathway can be found in several excellent recent reviews (Brozinick et al., 2007 Hou and Pessin, 2007; Huang and Czech, 2007;Larance et al., 2008 Sakamoto and Holman, 2008; Watson and Pessin, 2007; Zaid et al., 2008)One of the main objectives of this review is to discuss the results of the experiments measuring the kinetics of Glut4 movement between subcellular compartments in the context of our emerging model of the Glut4 trafficking pathway.
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Affiliation(s)
- Joseph M Muretta
- Department of Biochemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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33
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Compartmentalization and regulation of insulin signaling to GLUT4 by the cytoskeleton. VITAMINS AND HORMONES 2009; 80:193-215. [PMID: 19251039 DOI: 10.1016/s0083-6729(08)00608-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
One of the early events in the development of Type 2 diabetes appears to be an inhibition of insulin-mediated GLUT4 redistribution to the cell surface in tissues that express GLUT4. Understanding this process, and how it begins to breakdown in the development of insulin resistance is quite important as we face treatment and prevention of metabolic diseases. Over the past few years, and increasing number of laboratories have produced compelling data to demonstrate a role for both the actin and microtubule networks in the regulation of insulin-mediated GLUT4 redistribution to the cell surface. In this review, we explore this process from insulin-signal transduction to fusion of GLUT4 membrane vesicles, focusing on studies that have implicated a role for the cytoskeleton. We see from this body of work that both the actin network and the microtubule cytoskeleton play roles as targets of insulin action and effectors of insulin signaling leading to changes in GLUT4 redistribution to the cell surface and insulin-mediated glucose uptake.
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34
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The CREB coactivator CRTC2 links hepatic ER stress and fasting gluconeogenesis. Nature 2009; 460:534-7. [PMID: 19543265 PMCID: PMC2730924 DOI: 10.1038/nature08111] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 05/07/2009] [Indexed: 01/11/2023]
Abstract
In fasted mammals, circulating pancreatic glucagon stimulates hepatic gluconeogenesis in part through the CREB Regulated Transcription Coactivator 2 (CRTC2; also referred to as TORC2) 1,2. Hepatic glucose production is elevated in obesity, reflecting chronic increases in endoplasmic reticulum (ER) stress that promote insulin resistance 3. Whether ER stress also modulates the gluconeogenic program directly, however, is unclear. Here we show that CRTC2 functions as a dual sensor for ER stress and fasting signals in liver. Acute increases in ER stress triggered the dephosphorylation and nuclear entry of CRTC2, which in turn promoted the expression of ER quality control genes through an association with Activating Transcription Factor 6 alpha (ATF6α), an integral branch of the unfolded protein response 4–9. In addition to mediating CRTC2 recruitment to ER stress inducible promoters, ATF6α also reduced hepatic glucose output by disrupting the CREB:CRTC2 interaction and thereby inhibiting CRTC2 occupancy over gluconeogenic genes. Conversely, hepatic glucose output was upregulated when hepatic ATF6α protein amounts were reduced, either by RNAi-mediated knockdown or as a result of persistent stress in obesity. As ATF6α over-expression in livers of obese mice reversed CRTC2 effects on the gluconeogenic program and lowered hepatic glucose output, our results demonstrate how cross-talk between ER stress and fasting pathways at the level of a transcriptional coactivator contributes to glucose homeostasis.
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35
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Hartig SM, Ishikura S, Hicklen RS, Feng Y, Blanchard EG, Voelker KA, Pichot CS, Grange RW, Raphael RM, Klip A, Corey SJ. The F-BAR protein CIP4 promotes GLUT4 endocytosis through bidirectional interactions with N-WASp and Dynamin-2. J Cell Sci 2009; 122:2283-91. [PMID: 19509061 DOI: 10.1242/jcs.041343] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
F-BAR proteins are a newly described family of proteins with unknown physiological significance. Because F-BAR proteins, including Cdc42 interacting protein-4 (CIP4), drive membrane deformation and affect endocytosis, we investigated the role of CIP4 in GLUT4 traffic by flow cytometry in GLUT4myc-expressing L6 myoblasts (L6 GLUT4myc). L6 GLUT4myc cells express CIP4a as the predominant F-BAR protein. siRNA knockdown of CIP4 increased insulin-stimulated (14)C-deoxyglucose uptake by elevating cell-surface GLUT4. Enhanced surface GLUT4 was due to decreased endocytosis, which correlated with lower transferrin internalization. Immunoprecipitation of endogenous CIP4 revealed that CIP4 interacted with N-WASp and Dynamin-2 in an insulin-dependent manner. FRET confirmed the insulin-dependent, subcellular properties of these interactions. Insulin exposure stimulated specific interactions in plasma membrane and cytosolic compartments, followed by a steady-state response that underlies the coordination of proteins needed for GLUT4 traffic. Our findings reveal a physiological function for F-BAR proteins, supporting a previously unrecognized role for the F-BAR protein CIP4 in GLUT4 endocytosis, and show that interactions between CIP4 and Dynamin-2 and between CIP4 and NWASp are spatially coordinated to promote function.
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Affiliation(s)
- Sean M Hartig
- Division of Pediatrics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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36
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Konstantopoulos N, Molero-Navajas JC. The measurement of GLUT4 translocation in 3T3-L1 adipocytes. Methods Mol Biol 2009; 560:111-135. [PMID: 19504248 DOI: 10.1007/978-1-59745-448-3_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Type 2 diabetes (T2D) is one of the fastest growing threats to human health in westernised and developing countries and is associated with central obesity, atherosclerosis, dyslipidaemia, hyperinsulinaemia and hypertension. Insulin resistance, defined as a diminished response to ordinary levels of circulating insulin in one or more peripheral tissues, is an integral feature of T2D pathophysiology. This includes an impairment of insulin to inhibit hepatic glucose output and to stimulate glucose disposal into muscle and fat. While insulin is responsible for a number of specific biological responses, stimulation of glucose transport is critical for the maintenance of glucose homeostasis. The primary mechanism for insulin stimulation of glucose uptake into muscle and fat is the translocation of glucose transporter 4 (GLUT4) to the cell surface from intracellular storage vesicles within the cell. A major advantage in focussing on insulin regulation of glucose transport is that this represents the endpoint of multiple upstream signalling pathways. This chapter describes the measurement of GLUT4 translocation in cultured cells and its potential application for both mechanistic and therapeutic studies.
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Affiliation(s)
- Nicky Konstantopoulos
- Metabolic Research Unit, Deakin University, Pigdons Road, Waurn Ponds, Geelong, VIC 3217, Australia.
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37
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Abstract
The facilitative glucose transporter GLUT4, a recycling membrane protein, is required for dietary glucose uptake into muscle and fat cells. GLUT4 is also responsible for the increased glucose uptake by myofibres during muscle contraction. Defects in GLUT4 membrane traffic contribute to loss of insulin-stimulated glucose uptake in insulin resistance and Type 2 diabetes. Numerous studies have analysed the intracellular membrane compartments occupied by GLUT4 and the mechanisms by which insulin regulates GLUT4 exocytosis. However, until recently, GLUT4 internalization was less well understood. In the present paper, we review: (i) evidence supporting the co-existence of clathrin-dependent and independent GLUT4 internalization in adipocytes and muscle cells; (ii) the contrasting regulation of GLUT4 internalization by insulin in these cells; and (iii) evidence suggesting regulation of GLUT4 endocytosis in muscle cells by signals associated with muscle contraction.
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38
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Iaccio A, Cattaneo F, Mauro M, Ammendola R. FPRL1-mediated induction of superoxide in LL-37-stimulated IMR90 human fibroblast. Arch Biochem Biophys 2008; 481:94-100. [PMID: 18996352 DOI: 10.1016/j.abb.2008.10.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 10/16/2008] [Accepted: 10/23/2008] [Indexed: 12/25/2022]
Abstract
Molecular mechanisms underlying the generation of reactive oxygen species in LL-37-stimulated cells are poorly understood. Previously, we demonstrated that in human fibroblasts the exposure to WKYMVm induced p47(phox) phosphorylation and translocation and, in turn, NADPH oxidase activation. These effects were mediated by the activation of the Formyl-peptide receptor-like 1 (FPRL1) and the downstream signaling involved ERKs phosphorylation and PKCalpha- and PKCdelta-activation. Since LL-37 uses FPRL1 as a receptor to mediate its action on several cell types, we investigated in LL-37-stimulated IMR90 cells molecular mechanisms involved in NADPH-dependent superoxide generation. The exposure to LL-37, which is expressed in fibroblasts, induced ERKs activation, p47(phox) phosphorylation and translocation as well as NADPH oxidase activation. These effects were prevented by pertussis toxin, PD098059 and WRWWWW, a FPRL1-selective antagonist. Furthermore, the stimulation with LL-37 of HEK293 cells, transfected to stably express FPRL1, induced a rapid activation of ERKs and p47(phox) phosphorylation.
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Affiliation(s)
- Annalisa Iaccio
- Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy
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Application of immunocytochemistry and immunofluorescence techniques to adipose tissue and cell cultures. Methods Mol Biol 2008; 456:285-97. [PMID: 18516569 DOI: 10.1007/978-1-59745-245-8_21] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
When isolated from tissue, white adipose cells are round, and their interior is filled with a large (80-120 microm) droplet of stored triglyceride, leaving a thin (1-2-microm) layer of cytoplasm between the lipid droplet and the plasma membrane. Their three-dimensional architecture, together with the fact that these cells ordinarily float in medium, have created major challenges when one attempts to perform microscopy techniques with these cells. Adipocytes serve as the principal energy reservoir in the body, and it is essential to overcome these difficulties to be able to study hormone-mediated responses in real adipose cells, which convey physiological significance that cannot be readily duplicated by the use of cultured model adipocytes. This chapter focuses on the use of confocal microscopy optical sectioning and computer-assisted image reconstruction in the whole adipose cell in the study of insulin-regulated protein trafficking. In addition, we illustrate the possibility to image whole-mount preparations of living adipose tissue, opening new ways to probe adipose cells in situ without disrupting their cellular interactions within living adipose tissue. Confocal microscopy constitutes an effective morphological approach to investigating adipose cell physiology and pathophysiology.
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40
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Antonescu CN, Díaz M, Femia G, Planas JV, Klip A. Clathrin-dependent and independent endocytosis of glucose transporter 4 (GLUT4) in myoblasts: regulation by mitochondrial uncoupling. Traffic 2008; 9:1173-90. [PMID: 18435821 DOI: 10.1111/j.1600-0854.2008.00755.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In myocytes and adipocytes, insulin increases glucose transporter 4 (GLUT4) exocytosis by promoting GLUT4 vesicle docking/fusion with the membrane. Less is known about the mechanism and regulation of GLUT4 endocytosis, particularly in myocytes. Here, we show that GLUT4 internalization in L6 myoblasts was inhibited in part by hypertonicity or clathrin heavy chain knockdown and in part by cholesterol depletion. Both strategies had additive effects, abolishing GLUT4 endocytosis. GLUT4 internalization was abrogated by expressing dominant-negative dynamin-2 but unaffected by inhibiting caveolar-dependent endocytosis through syntaxin-6 knockdown or caveolin mutants (which reduced lactosylceramide endocytosis). Insulin did not affect GLUT4 internalization rate or sensitivity to clathrin or cholesterol depletion. In contrast, the mitochondrial uncoupler dinitrophenol (DNP), which like insulin increases surface GLUT4, reduced GLUT4 (but not transferrin) internalization, an effect additive to that of depleting clathrin but not cholesterol. Trout GLUT4 (a natural variant of GLUT4 bearing different endocytic motifs) exogenously expressed in mammalian L6 cells internalized only through the cholesterol-dependent route that also included the non-clathrin-dependent cargo interleukin-2 receptor beta, and DNP reduced internalization of both proteins. These results suggest that in muscle cells, GLUT4 internalizes simultaneously through clathrin-mediated endocytosis and a caveolae-independent but cholesterol- and dynamin-dependent route. Manipulating GLUT4 endocytosis to maintain surface GLUT4 may bypass insulin resistance.
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Affiliation(s)
- Costin N Antonescu
- Program in Cell Biology, The Hospital For Sick Children, Toronto, Ontario, Canada
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41
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Pilch PF. The mass action hypothesis: formation of Glut4 storage vesicles, a tissue-specific, regulated exocytic compartment. Acta Physiol (Oxf) 2008; 192:89-101. [PMID: 18171432 DOI: 10.1111/j.1748-1716.2007.01788.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Insulin stimulates glucose uptake into the target tissues of fat and muscle by recruiting or translocating Glut4 glucose transport proteins to their functional location at the cell surface. In the basal state, Glut4 is sequestered intracellularly in several vesicular compartments, one of which has come to be known as Glut4 storage vesicles (GSVs). The GSVs represent a tissue-specific compartment that is an ultimate target of the insulin signalling cascade. Glut4 translocation has been extensively studied because of its intrinsic scientific importance to cell biology as well as its relevance to the pathology of type 2 diabetes mellitus. I review herein the ontogeny of GSVs and their composition as it relates to a tissue-specific, hormone-sensitive exocytic compartment and propose a mechanism for their formation.
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Affiliation(s)
- P F Pilch
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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42
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Jiang L, Fan J, Bai L, Wang Y, Chen Y, Yang L, Chen L, Xu T. Direct quantification of fusion rate reveals a distal role for AS160 in insulin-stimulated fusion of GLUT4 storage vesicles. J Biol Chem 2007; 283:8508-16. [PMID: 18063571 DOI: 10.1074/jbc.m708688200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-stimulated GLUT4 translocation to the plasma membrane constitutes a key process for blood glucose control. However, convenient and robust assays to monitor this dynamic process in real time are lacking, which hinders current progress toward elucidation of the underlying molecular events as well as screens for drugs targeting this particular pathway. Here, we have developed a novel dual colored probe to monitor the translocation process of GLUT4 based on dual color fluorescence measurement. We demonstrate that this probe is more than an order of magnitude more sensitive than the current technology for detecting fusion events from single GLUT4 storage vesicles (GSVs). A small fraction of fusion events were found to be of the "kiss-and-run" type. For the first time, we show that insulin stimulation evokes a approximately 40-fold increase in the fusion of GSVs in 3T3-L1 adipocytes, compared with basal conditions. The probe can also be used to monitor the prefusion behavior of GSVs. By quantifying both the docking and fusion rates simultaneously, we demonstrate a proportional inhibition in both docking and fusion of GSVs by a dominant negative mutant of AS160, indicating a role for AS160 in the docking of GSVs but not in the regulation of GSV fusion after docking.
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Affiliation(s)
- Li Jiang
- Joint Laboratory of Institute of Biophysics & Huazhong University of Science and Technology, National Laboratory of Biomacromolecules, Chinese Academy of Sciences, Beijing, China
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43
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Ortegren U, Aboulaich N, Ost A, Strålfors P. A new role for caveolae as metabolic platforms. Trends Endocrinol Metab 2007; 18:344-9. [PMID: 17936007 DOI: 10.1016/j.tem.2007.08.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 08/14/2007] [Accepted: 08/14/2007] [Indexed: 11/19/2022]
Abstract
The plasma membrane of cells functions as a barrier to the environment. Caveolae are minute invaginations of the membrane that selectively carry out the exchange of information and materials with the environment, by functioning as organizers of signal transduction and through endocytosis. Recent findings of uptake of different metabolites and of lipid metabolism occurring in caveolae, point to a new general function of caveolae. As gateways for the uptake of nutrients across the plasma membrane, and as platforms for the metabolic conversion of nutrients, especially in adipocytes, caveolae are now emerging as active centers for many aspects of intermediary metabolism, with implications for our understanding of obesity, diabetes and other metabolic disorders.
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Affiliation(s)
- Unn Ortegren
- Department of Cell Biology and Diabetes Research Centre, Linköping University, SE58185, Linköping, Sweden
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44
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Fu Y, Luo L, Luo N, Zhu X, Garvey WT. NR4A orphan nuclear receptors modulate insulin action and the glucose transport system: potential role in insulin resistance. J Biol Chem 2007; 282:31525-33. [PMID: 17785466 DOI: 10.1074/jbc.m701132200] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
After observing that expression of two NR4A orphan nuclear receptors, NR4A3 and NR4A1, was altered by insulin in cDNA microarray analyses of human skeletal muscle, we studied whether these receptors could modulate insulin sensitivity. We found that both NR4A3 and NR4A1 were induced by insulin and by thiazolidinedione drugs (pioglitazone and troglitazone) in 3T3-L1 adipocytes. Furthermore, gene expression of NR4A3 and NR4A1 was reduced in skeletal muscles and adipose tissues from multiple rodent models of insulin resistance. To determine whether NR4A3 could modulate insulin sensitivity, 3T3-L1 adipocytes were stably transduced with NR4A3 or LacZ (control) lentiviral vectors. Compared with LacZ expressing cells, hyperexpression of NR4A3 increased the ability of insulin to augment glucose transport activity, and the mechanism involved increased recruitment of GLUT4 glucose transporters to the plasma membrane. NR4A3 hyperexpression also led to an increase in insulin-mediated tyrosine phosphorylation of insulin receptor substrate-1 as well as Akt phosphorylation. Suppression of NR4A3 using lentiviral short hairpin RNA constructs reduced the ability of insulin to stimulate glucose transport and phosphorylate Insulin receptor substrate-1 and Akt. Thus, NR4A3 and NR4A1 are attractive novel therapeutic targets for potential amelioration of insulin resistance, and treatment and prevention of type 2 diabetes and the metabolic syndrome.
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Affiliation(s)
- Yuchang Fu
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294-3360, USA.
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45
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Abstract
Despite being one of the first recognized targets of insulin action, the acceleration of glucose transport into muscle and fat tissue remains one of the most enigmatic processes in the insulin action cascade. Glucose transport is accomplished by a shift in the distribution of the insulin-responsive glucose transporter GLUT4 from intracellular compartments to the plasma membrane in the presence of insulin. The complexity in deciphering the molecular blueprint of insulin regulation of glucose transport arises because it represents a convergence of two convoluted biological systems-vesicular transport and signal transduction. Whereas more than 60 molecular players have been implicated in this orchestral performance, it has been difficult to distinguish between mainly passive participants vs. those that are clearly driving the process. The maze-like nature of the endosomal system makes it almost impossible to dissect the anatomical nature of what appears to be a medley of many overlapping and rapidly changing transitions. A major limitation is technology. It is clear that further progress in teasing apart the GLUT4 code will require the development and application of novel and advanced technologies that can discriminate one molecule from another in the living cell and to superimpose this upon a system in which the molecular environment can be carefully manipulated. Many are now taking on this challenge.
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Affiliation(s)
- Mark Larance
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Sydney 2010, Australia
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46
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Franck N, Stenkula KG, Ost A, Lindström T, Strålfors P, Nystrom FH. Insulin-induced GLUT4 translocation to the plasma membrane is blunted in large compared with small primary fat cells isolated from the same individual. Diabetologia 2007; 50:1716-22. [PMID: 17572871 DOI: 10.1007/s00125-007-0713-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 04/12/2007] [Indexed: 11/25/2022]
Abstract
AIMS/HYPOTHESIS Several studies have suggested that large fat cells are less responsive to insulin than small fat cells. However, in these studies, large fat cells from obese individuals were compared with smaller fat cells from leaner participants, in effect making it impossible to draw conclusions about whether there is a causal relationship between fat cell size and insulin sensitivity. We hypothesised that small fat cells might be more insulin-responsive than large adipocytes when obtained from the same individual. MATERIALS AND METHODS We developed a method of sorting isolated primary human fat cells by using nylon filters of two different pore sizes. The cells were stained to visualise DNA, which allowed discrimination from artefacts such as lipid droplets. The sorted cells were left to recover overnight, since we had previously demonstrated that this is necessary for correct assessment of insulin response. RESULTS We found similar amounts of the insulin receptor (IR), IRS-1 and GLUT4 when we compared small and large adipocytes from the same volunteer by immunoblotting experiments using the same total cell volume from both cell populations. Activation of IR, IRS-1 and Akt1 (also known as protein kinase B) by insulin was similar in the two cell populations. However, immunofluorescence confocal microscopy of plasma membrane sheets did not reveal any increase in the amount of GLUT4 in the plasma membrane following insulin stimulation in the large fat cells, whereas we saw a twofold increase in the amount of GLUT4 in the small fat cells. CONCLUSIONS/INTERPRETATION Our results support a causal relationship between the accumulation of large fat cells in obese individuals and reduced insulin responsiveness.
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Affiliation(s)
- N Franck
- Department of Medicine and Care, Linkoping University, Linkoping, Sweden
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47
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Hou JC, Pessin JE. Ins (endocytosis) and outs (exocytosis) of GLUT4 trafficking. Curr Opin Cell Biol 2007; 19:466-73. [PMID: 17644329 PMCID: PMC2041936 DOI: 10.1016/j.ceb.2007.04.018] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 04/17/2007] [Indexed: 12/21/2022]
Abstract
Glucose transporter 4 (GLUT4) is the major insulin-regulated glucose transporter expressed mainly in muscle and adipose tissue. GLUT4 is stored in a poorly characterized intracellular vesicular compartment and translocates to the cell surface in response to insulin stimulation resulting in an increased glucose uptake. This process is essential for the maintenance of normal glucose homeostasis and involves a complex interplay of trafficking events and intracellular signaling cascades. Recent studies have identified sortilin as an essential element for the formation of GLUT4 storage vesicles during adipogenesis and Golgi-localized gamma-ear-containing Arf-binding protein (GGA) as a key coat adaptor for the entry of newly synthesized GLUT4 into the specialized compartment. Insulin-stimulated GLUT4 translocation from this compartment to the plasma membrane appears to require the Akt/protein kinase B substrate termed AS160 (Akt substrate of 160kDa). In addition, the VPS9 domain-containing protein Gapex-5 in complex with CIP4 appears to function as a Rab31 guanylnucleotide exchange factor that is necessary for insulin-stimulated GLUT4 translocation. Here, we attempt to summarize recent advances in GLUT4 vesicle biogenesis, intracellular trafficking and membrane fusion.
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Affiliation(s)
- June Chunqiu Hou
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
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48
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Niu W, Ishiki M, Bilan PJ, Yao Z. Glucose transporter 4 can be inserted in the membrane without exposing its catalytic site for photolabeling from the medium. ACTA ACUST UNITED AC 2007; 50:147-54. [PMID: 17447020 DOI: 10.1007/s11427-007-0026-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 09/14/2006] [Indexed: 12/25/2022]
Abstract
Insulin stimulates the production of PI(3,4,5)P(3) in muscle cells, and this is required to stimulate GLUT4 fusion with the plasma membrane. Introduction of exogenous PI(3,4,5)P(3) to muscle cells recapitulates insulin's effects on GLUT4 fusion with the plasma membrane, but not glucose uptake. This study aims to explore the mechanism behind this difference. In L6-GLUT4myc muscle cells, the availability of the GLUT4 intracellular C-terminus and extracellular myc epitopes for immunoreactivity on plasma membrane lawns was detected with the corresponding antibody. The availability of the active site of GLUT4 from extracellular medium was assessed by affinity photolabeling with the cell impermeant compound Bio-LC-ATB-BMPA. 100 nmol/L insulin and 10 mumol/L PI(3,4,5)P(3) caused myc signal gain on the plasma membrane lawns by 1.64-fold and 1.58-fold over basal, respectively. Insulin, but not PI(3,4,5)P(3), increased photolabeling of GLUT4 and immunolabeling with C-terminus antibody by 2.47-fold and 2.04-fold over basal, respectively. Upon insulin stimulation, the C-terminus signal gain was greater than myc signal gain (2.04-fold vs. 1.64-fold over basal, respectively) in plasma membrane lawns. These results indicate that (i) PI(3,4,5)P(3) does not make the active site of GLUT4 available from the extracellular surface despite causing GLUT4 fusion with the plasma membrane; (ii) the availability of the active site of GLUT4 from the extracellular medium and availability of the C-terminus from the cytosolic site are correlated; (iii) in addition to stimulating GLUT4 translocation, insulin stimulation displaces a protein which masks the GLUT4 C-terminus. We propose that a protein which masks the C-terminus also prevents the active site from being available for photolabelling and possibly glucose uptake after treatment with PI(3,4,5)P(3).
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Affiliation(s)
- WenYan Niu
- Department of Immunology, Tianjin Medical University, Tianjin 300070, China.
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Huang S, Lifshitz LM, Jones C, Bellve KD, Standley C, Fonseca S, Corvera S, Fogarty KE, Czech MP. Insulin stimulates membrane fusion and GLUT4 accumulation in clathrin coats on adipocyte plasma membranes. Mol Cell Biol 2007; 27:3456-69. [PMID: 17339344 PMCID: PMC1899973 DOI: 10.1128/mcb.01719-06] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Total internal reflection fluorescence (TIRF) microscopy reveals highly mobile structures containing enhanced green fluorescent protein-tagged glucose transporter 4 (GLUT4) within a zone about 100 nm beneath the plasma membrane of 3T3-L1 adipocytes. We developed a computer program (Fusion Assistant) that enables direct analysis of the docking/fusion kinetics of hundreds of exocytic fusion events. Insulin stimulation increases the fusion frequency of exocytic GLUT4 vesicles by approximately 4-fold, increasing GLUT4 content in the plasma membrane. Remarkably, insulin signaling modulates the kinetics of the fusion process, decreasing the vesicle tethering/docking duration prior to membrane fusion. In contrast, the kinetics of GLUT4 molecules spreading out in the plasma membrane from exocytic fusion sites is unchanged by insulin. As GLUT4 accumulates in the plasma membrane, it is also immobilized in punctate structures on the cell surface. A previous report suggested these structures are exocytic fusion sites (Lizunov et al., J. Cell Biol. 169:481-489, 2005). However, two-color TIRF microscopy using fluorescent proteins fused to clathrin light chain or GLUT4 reveals these structures are clathrin-coated patches. Taken together, these data show that insulin signaling accelerates the transition from docking of GLUT4-containing vesicles to their fusion with the plasma membrane and promotes GLUT4 accumulation in clathrin-based endocytic structures on the plasma membrane.
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Affiliation(s)
- Shaohui Huang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Bai L, Wang Y, Fan J, Chen Y, Ji W, Qu A, Xu P, James DE, Xu T. Dissecting multiple steps of GLUT4 trafficking and identifying the sites of insulin action. Cell Metab 2007; 5:47-57. [PMID: 17189206 DOI: 10.1016/j.cmet.2006.11.013] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 10/17/2006] [Accepted: 11/17/2006] [Indexed: 01/24/2023]
Abstract
Insulin-stimulated GLUT4 translocation is central to glucose homeostasis. Functional assays to distinguish individual steps in the GLUT4 translocation process are lacking, thus limiting progress toward elucidation of the underlying molecular mechanism. Here we have developed a robust method, which relies on dynamic tracking of single GLUT4 storage vesicles (GSVs) in real time, for dissecting and systematically analyzing the docking, priming, and fusion steps of GSVs with the cell surface in vivo. Using this method, we have shown that the preparation of GSVs for fusion competence after docking at the surface is a key step regulated by insulin, whereas the docking step is regulated by PI3K and its downstream effector, the Rab GAP AS160. These data show that Akt-dependent phosphorylation of AS160 is not the major regulated step in GLUT4 trafficking, implicating alternative Akt substrates or alternative signaling pathways downstream of GSV docking at the cell surface as the major regulatory node.
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Affiliation(s)
- Li Bai
- Joint Laboratory of Institute of Biophysics and Huazhong University of Science and Technology, National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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