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Bishop EL, Gudgeon N, Fulton-Ward T, Stavrou V, Roberts J, Boufersaoui A, Tennant DA, Hewison M, Raza K, Dimeloe S. TNF-α signals through ITK-Akt-mTOR to drive CD4 + T cell metabolic reprogramming, which is dysregulated in rheumatoid arthritis. Sci Signal 2024; 17:eadg5678. [PMID: 38652761 DOI: 10.1126/scisignal.adg5678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 04/08/2024] [Indexed: 04/25/2024]
Abstract
Upon activation, T cells undergo metabolic reprogramming to meet the bioenergetic demands of clonal expansion and effector function. Because dysregulated T cell cytokine production and metabolic phenotypes coexist in chronic inflammatory disease, including rheumatoid arthritis (RA), we investigated whether inflammatory cytokines released by differentiating T cells amplified their metabolic changes. We found that tumor necrosis factor-α (TNF-α) released by human naïve CD4+ T cells upon activation stimulated the expression of a metabolic transcriptome and increased glycolysis, amino acid uptake, mitochondrial oxidation of glutamine, and mitochondrial biogenesis. The effects of TNF-α were mediated by activation of Akt-mTOR signaling by the kinase ITK and did not require the NF-κB pathway. TNF-α stimulated the differentiation of naïve cells into proinflammatory T helper 1 (TH1) and TH17 cells, but not that of regulatory T cells. CD4+ T cells from patients with RA showed increased TNF-α production and consequent Akt phosphorylation upon activation. These cells also exhibited increased mitochondrial mass, particularly within proinflammatory T cell subsets implicated in disease. Together, these findings suggest that T cell-derived TNF-α drives their metabolic reprogramming by promoting signaling through ITK, Akt, and mTOR, which is dysregulated in autoinflammatory disease.
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Affiliation(s)
- Emma L Bishop
- Institute of Immunology and Immunotherapy, University of Birmingham, B15 2TT Birmingham, UK
| | - Nancy Gudgeon
- Institute of Immunology and Immunotherapy, University of Birmingham, B15 2TT Birmingham, UK
| | - Taylor Fulton-Ward
- Institute of Immunology and Immunotherapy, University of Birmingham, B15 2TT Birmingham, UK
- Institute of Metabolism and Systems Research, University of Birmingham, B15 2TT Birmingham, UK
| | - Victoria Stavrou
- Institute of Immunology and Immunotherapy, University of Birmingham, B15 2TT Birmingham, UK
| | - Jennie Roberts
- Institute of Metabolism and Systems Research, University of Birmingham, B15 2TT Birmingham, UK
| | - Adam Boufersaoui
- Institute of Metabolism and Systems Research, University of Birmingham, B15 2TT Birmingham, UK
| | - Daniel A Tennant
- Institute of Metabolism and Systems Research, University of Birmingham, B15 2TT Birmingham, UK
| | - Martin Hewison
- Institute of Metabolism and Systems Research, University of Birmingham, B15 2TT Birmingham, UK
| | - Karim Raza
- Research into Inflammatory Arthritis Centre Versus Arthritis, Institute of Inflammation and Ageing, University of Birmingham, B15 2TT Birmingham, UK
- Sandwell and West Birmingham NHS Trust, B18 7QH Birmingham, UK
| | - Sarah Dimeloe
- Institute of Immunology and Immunotherapy, University of Birmingham, B15 2TT Birmingham, UK
- Institute of Metabolism and Systems Research, University of Birmingham, B15 2TT Birmingham, UK
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Dvorak NM, Domingo ND, Tapia CM, Wadsworth PA, Marosi M, Avchalumov Y, Fongsaran C, Koff L, Di Re J, Sampson CM, Baumgartner TJ, Wang P, Villarreal PP, Solomon OD, Stutz SJ, Aditi, Porter J, Gbedande K, Prideaux B, Green TA, Seeley EH, Samir P, Dineley KT, Vargas G, Zhou J, Cisneros I, Stephens R, Laezza F. TNFR1 signaling converging on FGF14 controls neuronal hyperactivity and sickness behavior in experimental cerebral malaria. J Neuroinflammation 2023; 20:306. [PMID: 38115011 PMCID: PMC10729485 DOI: 10.1186/s12974-023-02992-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/11/2023] [Indexed: 12/21/2023] Open
Abstract
BACKGROUND Excess tumor necrosis factor (TNF) is implicated in the pathogenesis of hyperinflammatory experimental cerebral malaria (eCM), including gliosis, increased levels of fibrin(ogen) in the brain, behavioral changes, and mortality. However, the role of TNF in eCM within the brain parenchyma, particularly directly on neurons, remains underdefined. Here, we investigate electrophysiological consequences of eCM on neuronal excitability and cell signaling mechanisms that contribute to observed phenotypes. METHODS The split-luciferase complementation assay (LCA) was used to investigate cell signaling mechanisms downstream of tumor necrosis factor receptor 1 (TNFR1) that could contribute to changes in neuronal excitability in eCM. Whole-cell patch-clamp electrophysiology was performed in brain slices from eCM mice to elucidate consequences of infection on CA1 pyramidal neuron excitability and cell signaling mechanisms that contribute to observed phenotypes. Involvement of identified signaling molecules in mediating behavioral changes and sickness behavior observed in eCM were investigated in vivo using genetic silencing. RESULTS Exploring signaling mechanisms that underlie TNF-induced effects on neuronal excitability, we found that the complex assembly of fibroblast growth factor 14 (FGF14) and the voltage-gated Na+ (Nav) channel 1.6 (Nav1.6) is increased upon tumor necrosis factor receptor 1 (TNFR1) stimulation via Janus Kinase 2 (JAK2). On account of the dependency of hyperinflammatory experimental cerebral malaria (eCM) on TNF, we performed patch-clamp studies in slices from eCM mice and showed that Plasmodium chabaudi infection augments Nav1.6 channel conductance of CA1 pyramidal neurons through the TNFR1-JAK2-FGF14-Nav1.6 signaling network, which leads to hyperexcitability. Hyperexcitability of CA1 pyramidal neurons caused by infection was mitigated via an anti-TNF antibody and genetic silencing of FGF14 in CA1. Furthermore, knockdown of FGF14 in CA1 reduced sickness behavior caused by infection. CONCLUSIONS FGF14 may represent a therapeutic target for mitigating consequences of TNF-mediated neuroinflammation.
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Affiliation(s)
- Nolan M Dvorak
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Nadia D Domingo
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX, 77555, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Cynthia M Tapia
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Paul A Wadsworth
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Mate Marosi
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Yosef Avchalumov
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Chanida Fongsaran
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Leandra Koff
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Jessica Di Re
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Catherine M Sampson
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Timothy J Baumgartner
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Pingyuan Wang
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Paula P Villarreal
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX, 77555, USA
- Clinical Sciences Program, The Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Olivia D Solomon
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Sonja J Stutz
- Center for Addiction Sciences and Therapeutics, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Aditi
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Jacob Porter
- Department of Chemistry, University of Texas, Austin, TX, 78712, USA
| | - Komi Gbedande
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX, 77555, USA
- Center for Immunity and Inflammation and Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, 07301, USA
| | - Brendan Prideaux
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Thomas A Green
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Erin H Seeley
- Department of Chemistry, University of Texas, Austin, TX, 78712, USA
| | - Parimal Samir
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Kelley T Dineley
- Center for Addiction Sciences and Therapeutics, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Gracie Vargas
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Jia Zhou
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Irma Cisneros
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Robin Stephens
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Center for Immunity and Inflammation and Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, 07301, USA.
| | - Fernanda Laezza
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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Majdoubi A, Lee JS, Kishta OA, Balood M, Moulefera MA, Ishido S, Talbot S, Cheong C, Alquier T, Thibodeau J. Lack of the E3 Ubiquitin Ligase March1 Affects CD8 T Cell Fate and Exacerbates Insulin Resistance in Obese Mice. Front Immunol 2020; 11:1953. [PMID: 32973799 PMCID: PMC7461985 DOI: 10.3389/fimmu.2020.01953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 07/20/2020] [Indexed: 01/08/2023] Open
Abstract
Obesity is a major risk factor for the development of insulin resistance and type 2 diabetes. However, the mechanisms that trigger the underlying adipose tissues inflammation are not completely understood. Here, we show that the E3 ubiquitin ligase March1 controls the phenotypic and functional properties of CD8+ T cells in mice white adipose tissue. In a diet-induced obesity model, mice lacking March1 [March1 knockout (KO)] show increased insulin resistance compared to their WT counterparts. Also, in obese March1 KO mice, the proportions of effector/memory (Tem) and resident/memory (Trm) CD8+ T cells were higher in the visceral adipose tissue, but not in the spleen. The effect of March1 on insulin resistance and on the phenotype of adipose tissue CD8+ T cells was independent of major histocompatibility complex class II ubiquitination. Interestingly, we adoptively transferred either WT or March1 KO splenic CD8+ T cells into obese WT chimeras that had been reconstituted with Rag1-deficient bone marrow. We observed an enrichment of Tem and Trm cells and exacerbated insulin resistance in mice that received March1 KO CD8 T cells. Mechanistically, we found that March1 deficiency alters the metabolic activity of CD8+ T cells. Our results provide additional evidence of the involvement of CD8+ T cells in adipose tissue inflammation and suggest that March1 controls the metabolic reprogramming of these cells.
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Affiliation(s)
- Abdelilah Majdoubi
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC, Canada
| | - Jun Seong Lee
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC, Canada
| | - Osama A Kishta
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC, Canada
| | - Mohammad Balood
- Département de Pharmacologie et Physiologie, Université de Montréal, Montreal, QC, Canada
| | | | - Satoshi Ishido
- Department of Microbiology, Hyogo College of Medicine, Nishinomiya, Japan
| | - Sébastien Talbot
- Département de Pharmacologie et Physiologie, Université de Montréal, Montreal, QC, Canada
| | - Cheolho Cheong
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, QC, Canada
| | - Thierry Alquier
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal Diabetes Research Center, and Département de Médicine, Université de Montréal, Montreal, QC, Canada
| | - Jacques Thibodeau
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC, Canada
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4
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Inokuchi JI, Inamori KI, Kabayama K, Nagafuku M, Uemura S, Go S, Suzuki A, Ohno I, Kanoh H, Shishido F. Biology of GM3 Ganglioside. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 156:151-195. [PMID: 29747813 DOI: 10.1016/bs.pmbts.2017.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Since the successful molecular cloning in 1998 of GM3 synthase (GM3S, ST3GAL5), the enzyme responsible for initiating biosynthesis of all complex gangliosides, the efforts of our research group have been focused on clarifying the physiological and pathological implications of gangliosides, particularly GM3. We have identified isoforms of GM3S proteins having distinctive lengths of N-terminal cytoplasmic tails, and found that these cytoplasmic tails define subcellular localization, stability, and in vivo activity of GM3S isoforms. Our studies of the molecular pathogenesis of type 2 diabetes, focused on interaction between insulin receptor and GM3 in membrane microdomains, led to a novel concept: type 2 diabetes and certain other lifestyle-related diseases are membrane microdomain disorders resulting from aberrant expression of gangliosides. This concept has enhanced our understanding of the pathophysiological roles of GM3 and related gangliosides in various diseases involving chronic inflammation, such as insulin resistance, leptin resistance, and T-cell function and immune disorders (e.g., allergic asthma). We also demonstrated an essential role of GM3 in murine and human auditory systems; a common pathological feature of GM3S deficiency is deafness. This is the first direct link reported between gangliosides and auditory functions.
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Affiliation(s)
- Jin-Ichi Inokuchi
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan.
| | - Kei-Ichiro Inamori
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | | | - Masakazu Nagafuku
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Satoshi Uemura
- Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Shinji Go
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Akemi Suzuki
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Isao Ohno
- Center for Medical Education, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Hirotaka Kanoh
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Fumi Shishido
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
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5
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Franklin JL, Bennett WL, Messina JL. Insulin attenuates TNFα-induced hemopexin mRNA: An anti-inflammatory action of insulin in rat H4IIE hepatoma cells. Biochem Biophys Rep 2017; 9:211-216. [PMID: 28956007 PMCID: PMC5614554 DOI: 10.1016/j.bbrep.2016.12.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 11/15/2016] [Accepted: 12/21/2016] [Indexed: 12/20/2022] Open
Abstract
Proinflammatory cytokines, including TNF-α and IL-6, can contribute to insulin resistance. Conversely, insulin has some actions that can be considered anti-inflammatory. Hemopexin is a Class 2 acute phase reactant and control of its transcription is predominantly regulated by IL-6, with TNF-α and IL-1β also inducing hemopexin gene expression. Thus, we asked whether insulin could inhibit the ability of TNF-α to stimulate hemopexin mRNA expression. In cultured rat hepatoma (H4IIE) cells, TNF-α significantly increased hemopexin mRNA accumulation. The TNF-α-induced increase of hemopexin mRNA was dramatically attenuated by insulin, even though TNF-α reduced peak insulin activation of ERK. Thus, even though TNF-α can contribute to insulin resistance, the residual insulin response was still able to counteract TNF-α actions. The TNF-α-induced increase of hemopexin mRNA was dramatically attenuated by insulin. This occurred even though TNF-α significantly decreased insulin activation of ERK. This suggests an additional mechanism for the anti-inflammatory action of insulin. Cytokine-induced insulin resistance does not abolish insulin’s anti-inflammatory effect.
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Affiliation(s)
- J Lee Franklin
- University of Alabama at Birmingham, Department of Pathology, Division of Molecular and Cellular Pathology, Birmingham, AL 35294, United States
| | - William L Bennett
- Yale University, Interventional Cardiology, New Haven, CT 06510, United States
| | - Joseph L Messina
- University of Alabama at Birmingham, Department of Pathology, Division of Molecular and Cellular Pathology, Birmingham, AL 35294, United States.,Veterans Administration Medical Center, Birmingham, AL 35294, United States
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6
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Rogers SW, Gahring LC. Upregulation of Nicotinic Acetylcholine Receptor alph4+beta2 through a Ligand-Independent PI3Kbeta Mechanism That Is Enhanced by TNFalpha and the Jak2/p38Mapk Pathways. PLoS One 2015; 10:e0143319. [PMID: 26619345 PMCID: PMC4664291 DOI: 10.1371/journal.pone.0143319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/03/2015] [Indexed: 11/17/2022] Open
Abstract
High affinity nicotine-binding sites in the mammalian brain are neuronal nicotinic acetylcholine receptors (nAChR) assembled from at least alpha4 and beta2 subunits into pentameric ion channels. When exposed to ligands such as nicotine, these receptors respond by undergoing upregulation, a correlate of nicotine addiction. Upregulation can be measured using HEK293 (293) cells that stably express alpha4 and beta2 subunits using quantification of [3H]epibatidine ([3H]Eb) binding to measure mature receptors. Treatment of these cells with choline also produces upregulation through a hemicholinium3 (HC3)-sensitive (choline kinase) and an HC3-insensitive pathway which are both independent of the mechanism used by nicotine for upregulation. In both cases, upregulation is significantly enhanced by the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα) which signals through its receptor Tnfr1 to activate p38Mapk. Here we report that the inhibition of class1 phosphoinositide 3-kinases isoform PI3Kbeta using the selective antagonist PI828 is alone sufficient to produce upregulation and enhance both nicotine and choline HC3-sensitive mediated upregulation. Further, these processes are impacted upon by an AG-490 sensitive Jak2-associated pathway. Both PI3Kbeta (negative) and Jak2 (positive) modulation of upregulation converge through p38Mapk and both overlap with TNFalpha enhancement of this process. Upregulation through the PI3Kbeta pathway did not require Akt. Collectively these findings support upregulation of endogenous alpha4beta2 as a balance among cellular signaling networks that are highly responsive to multiple environmental, inflammatory and metabolic agents. The findings also suggest how illness and metabolic stress could alter the expression of this important nicotinic receptor and novel avenues to intercede in modifying its expression.
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Affiliation(s)
- Scott W Rogers
- Salt Lake City Veteran's Administration Geriatric Research, Education and Clinical Center, Salt Lake City, Utah, 84148, United States of America.,Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, 84132, United States of America
| | - Lorise C Gahring
- Salt Lake City Veteran's Administration Geriatric Research, Education and Clinical Center, Salt Lake City, Utah, 84148, United States of America.,Department of Internal Medicine, Division of Geriatrics, University of Utah School of Medicine, Salt Lake City, Utah, 84132, United States of America
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Taher M, Mohamed Amiroudine MZA, Tengku Zakaria TMFS, Susanti D, Ichwan SJA, Kaderi MA, Ahmed QU, Zakaria ZA. α-Mangostin Improves Glucose Uptake and Inhibits Adipocytes Differentiation in 3T3-L1 Cells via PPARγ, GLUT4, and Leptin Expressions. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2015; 2015:740238. [PMID: 25873982 PMCID: PMC4385643 DOI: 10.1155/2015/740238] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 02/06/2023]
Abstract
Obesity has been often associated with the occurrence of cardiovascular diseases, type 2 diabetes, and cancer. The development of obesity is also accompanied by significant differentiation of preadipocytes into adipocytes. In this study, we investigated the activity of α-mangostin, a major xanthone component isolated from the stem bark of G. malaccensis, on glucose uptake and adipocyte differentiation of 3T3-L1 cells focusing on PPARγ, GLUT4, and leptin expressions. α-Mangostin was found to inhibit cytoplasmic lipid accumulation and adipogenic differentiation. Cells treated with 50 μM of α-mangostin reduced intracellular fat accumulation dose-dependently up to 44.4% relative to MDI-treated cells. Analyses of 2-deoxy-D-[(3)H] glucose uptake activity showed that α-mangostin significantly improved the glucose uptake (P < 0.05) with highest activity found at 25 μM. In addition, α-mangostin increased the amount of free fatty acids (FFA) released. The highest glycerol release level was observed at 50 μM of α-mangostin. qRT-PCR analysis showed reduced lipid accumulation via inhibition of PPARγ gene expression. Induction of glucose uptake and free fatty acid release by α-mangostin were accompanied by increasing mRNA expression of GLUT4 and leptin. These evidences propose that α-mangostin might be possible candidate for the effective management of obesity in future.
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Affiliation(s)
- Muhammad Taher
- Department of Pharmaceutical Technology, Faculty of Pharmacy, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Mohamed Zaffar Ali Mohamed Amiroudine
- Department of Pharmaceutical Technology, Faculty of Pharmacy, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Tengku Muhamad Faris Syafiq Tengku Zakaria
- Department of Pharmaceutical Technology, Faculty of Pharmacy, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Deny Susanti
- Department of Chemistry, Faculty of Science, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Solachuddin J. A. Ichwan
- Faculty of Dentistry, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Pahang, Malaysia
| | - Mohd Arifin Kaderi
- Faculty of Allied Health Science, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Qamar Uddin Ahmed
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, International Islamic University Malaysia, Jalan Istana, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Zainul Amiruddin Zakaria
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
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8
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Andrographolide inhibits nuclear factor-κB activation through JNK-Akt-p65 signaling cascade in tumor necrosis factor-α-stimulated vascular smooth muscle cells. ScientificWorldJournal 2014; 2014:130381. [PMID: 25114952 PMCID: PMC4121194 DOI: 10.1155/2014/130381] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 06/30/2014] [Indexed: 11/24/2022] Open
Abstract
Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Andrographolide is the most active and critical constituent isolated from the leaves of Andrographis paniculata, a herbal medicine widely used for treating anti-inflammation in Asia. In this study, we investigated the mechanisms of the inhibitory effects of andrographolide in vascular smooth muscle cells (VSMCs) exposed to a proinflammatory stimulus, tumor necrosis factor-α (TNF-α). Treating TNF-α-stimulated VSMCs with andrographolide suppressed the expression of inducible nitric oxide synthase in a concentration-dependent manner. A reduction in TNF-α-induced c-Jun N-terminal kinase (JNK), Akt, and p65 phosphorylation was observed in andrographolide-treated VSMCs. However, andrographolide affected neither IκBα degradation nor p38 mitogen-activated protein kinase or extracellular signal-regulated kinase 1/2 phosphorylation under these conditions. Both treatment with LY294002, a phosphatidylinositol 3-kinase/Akt inhibitor, and treatment with SP600125, a JNK inhibitor, markedly reversed the andrographolide-mediated inhibition of p65 phosphorylation. In addition, LY294002 and SP600125 both diminished Akt phosphorylation, whereas LY294002 had no effects on JNK phosphorylation. These results collectively suggest that therapeutic interventions using andrographolide can benefit the treatment of vascular inflammatory diseases, and andrographolide-mediated inhibition of NF-κB activity in TNF-α-stimulated VSMCs occurs through the JNK-Akt-p65 signaling cascade, an IκBα-independent mechanism.
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Abstract
We demonstrated the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and GM3 ganglioside in adipocytes and propose a working hypothesis "metabolic disorders, such as type 2 diabetes, are membrane microdomain disorders caused by aberrant expression of gangliosides". It is expected that the development of novel diagnosis of metabolic syndrome by identifying the specific ganglioside species and a therapeutic strategy "membrane microdomain ortho-signaling therapy".
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Affiliation(s)
- Jin-ichi Inokuchi
- Division of Glycopathology, Institute of Molecular Biomembranes and Glycobiology, Tohoku Pharmaceutical University, 4-4-1, komatsushima, Aoba-ku, Sendai, 981-8558, Miyagi, Japan,
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10
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Nohara A, Okada S, Ohshima K, Pessin JE, Mori M. Cyclin-dependent kinase-5 is a key molecule in tumor necrosis factor-α-induced insulin resistance. J Biol Chem 2011; 286:33457-65. [PMID: 21813649 DOI: 10.1074/jbc.m111.231431] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of TNF-α-induced insulin resistance has remained unresolved with evidence for down-regulation of insulin effector targets effects or blockade of proximal as well as distal insulin signaling events depending upon the dose, time, and cell type examined. To address this issue we examined the acute actions of TNF-α in differentiated 3T3L1 adipocytes. Acute (5-15 min) treatment with 20 ng/ml (~0.8 nm) TNF-α had no significant effect on IRS1-associated phosphatidylinositol 3-kinase. In contrast, TNF-α increased insulin-stimulated cyclin-dependent kinase-5 (CDK5) phosphorylation on tyrosine residue 15 through an Erk-dependent pathway and up-regulated the expression of the CDK5 regulator protein p35. In parallel, TNF-α stimulation also resulted in the phosphorylation and GTP loading of the Rho family GTP-binding protein, TC10α. TNF-α enhanced the depolymerization of cortical F-actin and inhibited insulin-stimulated glucose transporter-4 (GLUT4) translocation. Treatment with the MEK inhibitor, PD98059, blocked the TNF-α-induced increase in CDK5 phosphorylation and the depolymerization of cortical F-actin. Conversely, siRNA-mediated knockdown of CDK5 or treatment with the MEK inhibitor restored the impaired insulin-stimulated GLUT4 translocation induced by TNF-α. Furthermore, siRNA-mediated knockdown of p44/42 Erk also rescued the TNF-α inhibition of insulin-stimulated GLUT4 translocation. Together, these data demonstrate that TNF-α-mediated insulin resistance of glucose uptake can occur through a MEK/Erk-dependent activation of CDK5.
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Affiliation(s)
- Atsushi Nohara
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Japan
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11
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Inhibition of human in-stent restenosis: a molecular view. Curr Opin Pharmacol 2011; 11:372-7. [DOI: 10.1016/j.coph.2011.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Accepted: 03/21/2011] [Indexed: 12/20/2022]
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12
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Chang CZ, Wu SC, Kwan AL, Lin CL, Hwang SL. 6-Mercaptopurine reverses experimental vasospasm and alleviates the production of endothelins in NO-independent mechanism-a laboratory study. Acta Neurochir (Wien) 2011; 153:939-49. [PMID: 21170559 DOI: 10.1007/s00701-010-0865-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 10/29/2010] [Indexed: 10/18/2022]
Abstract
INTRODUCTION Increased endothelin-1 (ET-1) production and diminished nitric oxide synthase (NOS) bioavailability has been observed in aneurysmal subarachnoid hemorrhage (SAH). The authors previously found that 6-mercaptopurine (6-mp) is effective in preventing and reversing arterial narrowing in a rodent SAH model. This present study is of interest to examine the effect of 6-mp on ET-1/endothelial nitric oxide synthase (eNOS) in this animal model. METHODS A rodent double hemorrhage SAH model was employed. Animals were randomly assigned to six groups (sham, SAH only, vehicle, 0.5, 1.0 and 2 mg kg(-1) day(-1) 6-mp treatment). Monoclonal CD45 immunostaining was utilized to evaluate monocytes and microglia. The level of pro-inflammatory cytokines, such as IL-1, IL-6 and TNF-α(RT-PCR), and ET-1 (ELISA) was measured. The basilar arteries (BAs) were harvested and sliced, and their cross-sectional areas were determined. Radiolabeled NOS assay kit was applied to detect eNOS. RESULTS Morphologically, convolution of internal elastic lamina, endothelial cells distortion, and necrotic smooth muscle were prevalently present in the basilar artery of SAH groups, which was absent in the 1 and 2 mg kg(-1) day(-1) 6-mp plus SAH group or the healthy controls. Significant vasospasm was noted in the vehicle group (lumen patency, 54.6%, p ≤ 0.01 compared with the sham group), but it was less prominent in the 2 mg kg(-1) day(-1) 6-mp treatment group (lumen patency, 87.6%, p < 0.05). In addition, administration with 2 mg kg(-1) day(-1) 6-mp reduced cytokine levels by 11%, 47%, and 34% for IL-1, IL-6, and TNF-α, respectively, and increased ET-1 levels were found in all the animals subject to SAH (SAH only, SAH plus vehicle, SAH plus 0.5 and 1.0 mg kg(-1) day(-1) 6-mp) except in the 2 mg kg(-1) day(-1) 6-mp SAH group, when compared with the healthy controls (no SAH). Meanwhile, treatment with 6-mp did not induce the levels of expressed eNOS in BAs in the 6-mp groups (0.5, 1.0, and 2 mg kg(-1) day(-1) 6-mp plus SAH) when compared with that in the SAH groups (p > 0.1). CONCLUSION In summary, treatment with 6-mp decreased the release of pro-inflammatory cytokines and diminished experimental vasospasm. This study offered first evidence that 6-mp dose-dependently reduces the level of ET-1 in a NO-independent mechanism, which corresponds to its antivasospastic effect in the condition of chronic vasospasm.
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MESH Headings
- Aneurysm, Ruptured/pathology
- Aneurysm, Ruptured/physiopathology
- Animals
- Chemotaxis/drug effects
- Connective Tissue/drug effects
- Connective Tissue/pathology
- Cytokines/metabolism
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Endothelin-1/metabolism
- Immunosuppressive Agents/pharmacology
- Inflammation Mediators/metabolism
- Intracranial Aneurysm/pathology
- Intracranial Aneurysm/physiopathology
- Male
- Mercaptopurine/pharmacology
- Microglia/drug effects
- Microglia/pathology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/pathology
- Nitric Oxide/physiology
- Nitric Oxide Synthase/metabolism
- Rats
- Rats, Sprague-Dawley
- Subarachnoid Hemorrhage/pathology
- Subarachnoid Hemorrhage/physiopathology
- Vasospasm, Intracranial/pathology
- Vasospasm, Intracranial/physiopathology
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Affiliation(s)
- Chih-Zen Chang
- Department of Surgery, College of Medicine, Kaohsiung Medical University, Taiwan, Republic of China.
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13
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Inokuchi JI. Physiopathological function of hematoside (GM3 ganglioside). PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2011; 87:179-98. [PMID: 21558756 PMCID: PMC3149380 DOI: 10.2183/pjab.87.179] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Since I was involved in the molecular cloning of GM3 synthase (SAT-I), which is the primary enzyme for the biosynthesis of gangliosides in 1998, my research group has been concentrating on our efforts to explore the physiological and pathological implications of gangliosides especially for GM3. During the course of study, we demonstrated the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and gangliosides in membrane microdomains and propose a new concept: Life style-related diseases, such as type 2 diabetes, are a membrane microdomain disorder caused by aberrant expression of gangliosides. We also encountered an another interesting aspect indicating the indispensable role of gangliosides in auditory system. After careful behavioral examinations of SAT-I knockout mice, their hearing ability was seriously impaired with selective degeneration of the stereocilia of hair cells in the organ of Corti. This is the first observation demonstrating a direct link between gangliosides and hearing functions.
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Affiliation(s)
- Jin-ichi Inokuchi
- Division of Glycopathology, Institute of Molecular Biomembranes and Glycobiology, Tohoku Pharmaceutical University, Miyagi, Japan.
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14
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Inhibition of ganglioside biosynthesis as a novel therapeutic approach in insulin resistance. Handb Exp Pharmacol 2011:165-78. [PMID: 21484572 DOI: 10.1007/978-3-642-17214-4_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A new concept "Life style-related diseases, such as type 2 diabetes, are a membrane microdomain disorder caused by aberrant expression of gangliosides" has arisen. By examining this working hypothesis, we demonstrate the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and gangliosides in microdomains microdomains and propose the new therapeutic strategy "membrane microdomain ortho-signaling therapy".
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15
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Ye J, Keller JN. Regulation of energy metabolism by inflammation: a feedback response in obesity and calorie restriction. Aging (Albany NY) 2010; 2:361-8. [PMID: 20606248 PMCID: PMC2919256 DOI: 10.18632/aging.100155] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Caloric
restriction (CR), in the absence of malnutrition, delays aging and prevents
aging-related diseases through multiple mechanisms. A reduction in chronic
inflammation is widely observed in experimental models of caloric
restriction. The low inflammation status may contribute to the reduced
incidence of osteoporosis, Alzheimer's disease, cardiovascular diseases and
cancer in the aging subjects. The association of caloric restriction with
low inflammation suggests a role of energy accumulation in the origin of
the chronic inflammation. This point is enforced by recent advances in
obesity research. Abundant literature on obesity suggests that chronic
inflammation is a consequence of energy accumulation in the body. The
emerging evidence strongly supports that the inflammatory response induces
energy expenditure in a feedback manner to fight against energy surplus in
obesity.
If
this feedback system is deficient (Inflammation Resistance), energy
expenditure will be reduced and energy accumulation will lead to obesity. In this perspective, we propose
that an increase in inflammation in obesity promotes energy expenditure
with a goal to get rid of energy surplus. A decrease in inflammation under
caloric restriction contributes to energy saving. Inflammation is a
mechanism for energy balance in the body. Inflammation resistance will lead
to obesity. We will review the recent literature in support of the
viewpoints.
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Affiliation(s)
- Jianping Ye
- Pennington Biomedical Research Center, Louisiana State University System, LA 70808, USA
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16
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Mehta NN, McGillicuddy FC, Anderson PD, Hinkle CC, Shah R, Pruscino L, Tabita-Martinez J, Sellers KF, Rickels MR, Reilly MP. Experimental endotoxemia induces adipose inflammation and insulin resistance in humans. Diabetes 2010; 59:172-81. [PMID: 19794059 PMCID: PMC2797919 DOI: 10.2337/db09-0367] [Citation(s) in RCA: 256] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE An emerging model of metabolic syndrome and type 2 diabetes is of adipose dysfunction with leukocyte recruitment into adipose leading to chronic inflammation and insulin resistance (IR). This study sought to explore potential mechanisms of inflammatory-induced IR in humans with a focus on adipose tissue. RESEARCH DESIGN AND METHODS We performed a 60-h endotoxemia protocol (3 ng/kg intravenous bolus) in healthy adults (n = 20, 50% male, 80% Caucasian, aged 27.3 +/- 4.8 years). Before and after endotoxin, whole-blood sampling, subcutaneous adipose biopsies, and frequently sampled intravenous glucose tolerance (FSIGT) testing were performed. The primary outcome was the FSIGT insulin sensitivity index (S(i)). Secondary measures included inflammatory and metabolic markers and whole-blood and adipose mRNA and protein expression. RESULTS Endotoxemia induced systemic IR as demonstrated by a 35% decrease in S(i) (3.17 +/- 1.66 to 2.06 +/- 0.73 x 10(-4) [microU * ml(-1) * min(-1)], P < 0.005), while there was no effect on pancreatic beta-cell function. In adipose, endotoxemia suppressed insulin receptor substrate-1 and markedly induced suppressor of cytokine signaling proteins (1 and 3) coincident with local activation of innate (interleukin-6, tumor necrosis factor) and adaptive (monocyte chemoattractant protein-1 and CXCL10 chemokines) inflammation. These changes are known to attenuate insulin receptor signaling in model systems. CONCLUSIONS We demonstrate, for the first time in humans, that acute inflammation induces systemic IR following modulation of specific adipose inflammatory and insulin signaling pathways. It also provides a rationale for focused mechanistic studies and a model for human proof-of-concept trials of novel therapeutics targeting adipose inflammation in IR and related consequences in humans.
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Affiliation(s)
- Nehal N. Mehta
- the Cardiovascular Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- the Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Institute for Diabetes Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Fiona C. McGillicuddy
- the Cardiovascular Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- the Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Paul D. Anderson
- Department of Medicine, Darthmouth Hitchcock Medical Center, Lebanon, New Hampshire
| | - Christine C. Hinkle
- the Cardiovascular Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- the Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Rachana Shah
- Institute for Diabetes Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Leticia Pruscino
- the Cardiovascular Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- the Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Jennifer Tabita-Martinez
- the Cardiovascular Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Kim F. Sellers
- Department of Biostatistics, Georgetown University Medical School, Washington, D.C
| | - Michael R. Rickels
- the Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Institute for Diabetes Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Muredach P. Reilly
- the Cardiovascular Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- the Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Institute for Diabetes Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Corresponding author: Muredach P. Reilly,
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17
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Inokuchi JI. Membrane microdomains and insulin resistance. FEBS Lett 2009; 584:1864-71. [PMID: 19822143 DOI: 10.1016/j.febslet.2009.10.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 10/03/2009] [Accepted: 10/06/2009] [Indexed: 11/18/2022]
Abstract
A new concept, that "metabolic disorders, such as type 2 diabetes, are membrane microdomain disorders caused by aberrant expression of gangliosides", has arisen. By examining this working hypothesis, we demonstrate the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and gangliosides in microdomains and propose the new therapeutic strategy "membrane microdomain ortho-signaling therapy".
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Affiliation(s)
- Jin-ichi Inokuchi
- Division of Glycopathology, Institute of Molecular Biomembranes and Glycobiology, Tohoku Pharmaceutical University, Aoba-ku, Sendai, Miyagi, Japan.
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18
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Kroczynska B, Kaur S, Platanias LC. Growth suppressive cytokines and the AKT/mTOR pathway. Cytokine 2009; 48:138-43. [PMID: 19682919 DOI: 10.1016/j.cyto.2009.07.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 07/06/2009] [Indexed: 11/29/2022]
Abstract
The mTOR signaling pathway plays a very important role in the transmission of signals for initiation of mRNA translation and protein expression in mammalian cells. mTOR activates various downstream effectors to promote initiation of cap-dependent mRNA translation and mediate pro-mitogenic and pro-survival signals. Recent evidence has implicated effectors of this signaling cascade in mRNA translation for interferon stimulated genes (ISGs). In addition, it was recently shown that AKT/mTOR-mediated signals play important roles in the generation of IFN-dependent antiviral and growth inhibitory responses, suggesting that mTOR and its effectors can mediate diverse biological responses, depending on the cellular context and the triggering stimuli. In this review, the regulatory effects of various growth suppressive cytokines on the mTOR pathway are summarized and the emerging new functions of mTOR are discussed.
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Affiliation(s)
- Barbara Kroczynska
- Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School, 303 East Superior Street, Lurie 3-107, Chicago, IL 60611, USA
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19
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Aga M, Arai N, Ohashi E, Ariyasu T, Arai S, Iwaki K, Ohta T, Fukuda S. Propolis Enhances Adipocyte Differentiation and Prevents Insulin Resistance in 3T3-L1 cells (Propolis improves insulin resistance in vitro). J JPN SOC FOOD SCI 2009. [DOI: 10.3136/nskkk.56.31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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20
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Ito Y, Daitoku H, Fukamizu A. Foxo1 increases pro-inflammatory gene expression by inducing C/EBPbeta in TNF-alpha-treated adipocytes. Biochem Biophys Res Commun 2008; 378:290-5. [PMID: 19026986 DOI: 10.1016/j.bbrc.2008.11.043] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 11/12/2008] [Indexed: 01/09/2023]
Abstract
Obesity is associated with a low-grade inflammation in adipose tissue resulting from increased production of pro-inflammatory cytokines and which can subsequently contribute to the development of insulin resistance. However, the mechanisms underlying the transcriptional regulation of pro-inflammatory genes are still unclear. Here we show that tumor necrosis factor (TNF)-alpha treatment attenuated Akt-dependent phosphorylation of Foxo1 and enhanced transcriptional activity of Foxo1. We found that Foxo1 increased the expression of CCAAT/enhancer binding protein (C/EBPbeta, a positive regulator of monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-6 genes, through directly binding to its promoter. Furthermore, knockdown of Foxo1 as well as C/EBPbeta inhibits TNF-alpha-induced expression of MCP-1 and IL-6 in 3T3-L1 adipocytes. These findings suggest that activation of Foxo1 triggered by TNF-alpha up-regulates the expression of C/EBPbeta in 3T3-L1 adipocytes, thereby leading to an increased production of pro-inflammatory cytokines, MCP-1 and IL-6.
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Affiliation(s)
- Yu Ito
- Center for Tsukuba Advanced Research Alliance, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8577, Japan
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21
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The adipose triglyceride lipase, adiponectin and visfatin are downregulated by tumor necrosis factor-alpha (TNF-alpha) in vivo. Cytokine 2008; 45:12-9. [PMID: 19026557 DOI: 10.1016/j.cyto.2008.10.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 08/03/2008] [Accepted: 10/10/2008] [Indexed: 11/22/2022]
Abstract
Inflammatory cytokines have been linked to obesity-related insulin resistance. To investigate the effect of TNF-alpha, an inflammatory cytokine, on insulin action, C57BL/6J mice were treated with TNF-alpha for 7 days after which we examined the in vivo effects of TNF-alpha on glucose tolerance and insulin sensitivity with IV glucose tolerance tests and hyperinsulinemic-euglycemic clamps. In addition, we analyzed the in vivo effect of TNF-alpha on several metabolism-related genes and adipocytokines implicated in the development of insulin resistance. TNF-alpha treatment resulted in markedly increased fasting blood glucose, insulin and free fatty acids (FFA) levels and reduced glucose tolerance. During the clamps, the rates insulin-stimulated whole body (G(Rd)) and skeletal muscle glucose uptake (MGU) and insulin's ability to suppress hepatic glucose production (HGP) were decreased in TNF-alpha treated animals, indicating insulin resistance. In addition, both PPARgamma and ATGL mRNA expression in adipose tissues as well as ATGL protein levels in plasma were downregulated. Moreover, adipose mRNA expression and plasma protein levels of adiponectin and visfatin were significantly down-regulated. We conclude that the alterations of PPARgamma, ATGL, adiponectin and visfatin may contribute to the development of insulin resistance mediated by TNF-alpha.
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22
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Pincheira R, Castro AF, Ozes ON, Idumalla PS, Donner DB. Type 1 TNF Receptor Forms a Complex with and Uses Jak2 and c-Src to Selectively Engage Signaling Pathways That Regulate Transcription Factor Activity. THE JOURNAL OF IMMUNOLOGY 2008; 181:1288-98. [DOI: 10.4049/jimmunol.181.2.1288] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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23
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TNFalpha is a potent inducer of platelet-activating factor synthesis in adipocytes but not in preadipocytes. Differential regulation by PI3K. Cytokine 2008; 41:174-81. [PMID: 18180165 DOI: 10.1016/j.cyto.2007.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 10/15/2007] [Accepted: 11/19/2007] [Indexed: 11/20/2022]
Abstract
Tumour necrosis factor alpha (TNFalpha) induces platelet-activating factor (PAF) synthesis in many inflammatory cells. Here, we investigate the possibility that TNFalpha stimulates PAF synthesis in rat adipocytes and preadipocytes and that phosphoinositide 3-kinase (PI3K) and extracellular signal-regulated kinase 1/2 (ERK1/2) are implicated in this process. Primary cultures were incubated with [3H]lyso-PAF and stimulated by TNFalpha in the presence or absence of wortmannin. We found that, although both cultures synthesized PAF at a similar basal rate, TNFalpha-induced PAF synthesis in adipocytes was 7-fold higher than in preadipocytes. This suggested a maturation of PAF-TNFalpha interrelationship during adipocyte differentiation. Wortmannin enhanced TNFalpha-dependent PAF synthesis in adipocytes but not in preadipocytes, indicating the negative control by PI3K in mature cells. PAF increase was due to the regulation of its biosynthesis since PAF-acetylhydrolase (PAF-AH) activity was TNFalpha- and wortmannin-independent. Our hypothesis is that PAF mediates TNFalpha inflammatory effects in both adipocytes and preadipocytes and that this pathway is enhanced during adipocyte differentiation, a mechanism which is highly active during the development of obesity.
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Kabayama K, Sato T, Saito K, Loberto N, Prinetti A, Sonnino S, Kinjo M, Igarashi Y, Inokuchi JI. Dissociation of the insulin receptor and caveolin-1 complex by ganglioside GM3 in the state of insulin resistance. Proc Natl Acad Sci U S A 2007; 104:13678-83. [PMID: 17699617 PMCID: PMC1949342 DOI: 10.1073/pnas.0703650104] [Citation(s) in RCA: 293] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Membrane microdomains (lipid rafts) are now recognized as critical for proper compartmentalization of insulin signaling. We previously demonstrated that, in adipocytes in a state of TNFalpha-induced insulin resistance, the inhibition of insulin metabolic signaling and the elimination of insulin receptors (IR) from the caveolae microdomains were associated with an accumulation of the ganglioside GM3. To gain insight into molecular mechanisms behind interactions of IR, caveolin-1 (Cav1), and GM3 in adipocytes, we have performed immunoprecipitations, cross-linking studies of IR and GM3, and live cell studies using total internal reflection fluorescence microscopy and fluorescence recovery after photobleaching techniques. We found that (i) IR form complexes with Cav1 and GM3 independently; (ii) in GM3-enriched membranes the mobility of IR is increased by dissociation of the IR-Cav1 interaction; and (iii) the lysine residue localized just above the transmembrane domain of the IR beta-subunit is essential for the interaction of IR with GM3. Because insulin metabolic signal transduction in adipocytes is known to be critically dependent on caveolae, we propose a pathological feature of insulin resistance in adipocytes caused by dissociation of the IR-Cav1 complex by the interactions of IR with GM3 in microdomains.
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Affiliation(s)
- Kazuya Kabayama
- *Division of Glycopathology, Institute of Molecular Biomembranes and Glycobiology, Tohoku Pharmaceutical University, 4-4-1, Komatsushima, Aoba-ku, Sendai 981-8558, Miyagi, Japan
| | - Takashige Sato
- Department of Biomembrane and Biofunctional Chemistry, School of Pharmaceutical Sciences and Pharmacy, and
| | - Kumiko Saito
- Department of Biomembrane and Biofunctional Chemistry, School of Pharmaceutical Sciences and Pharmacy, and
| | - Nicoletta Loberto
- Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, Via Fratelli Cervi 93, Segrate 20090, Milan, Italy; and
| | - Alessandro Prinetti
- Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, Via Fratelli Cervi 93, Segrate 20090, Milan, Italy; and
| | - Sandro Sonnino
- Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, Via Fratelli Cervi 93, Segrate 20090, Milan, Italy; and
| | - Masataka Kinjo
- Laboratory of Supramolecular Biophysics, Research Institute for Electronic Science, Hokkaido University, Nishi 6, Kita 12, Kita-ku, Sapporo 060-0812, Japan
| | - Yasuyuki Igarashi
- Department of Biomembrane and Biofunctional Chemistry, School of Pharmaceutical Sciences and Pharmacy, and
| | - Jin-ichi Inokuchi
- *Division of Glycopathology, Institute of Molecular Biomembranes and Glycobiology, Tohoku Pharmaceutical University, 4-4-1, Komatsushima, Aoba-ku, Sendai 981-8558, Miyagi, Japan
- Core Research for Evolutional Science and Technology Program, Japan Science and Technology Agency, 4-1-8, Honcho Kawaguchi, Saitama 332-0012, Japan
- To whom correspondence should be addressed. E-mail:
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25
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Abstract
Membrane microdomains (lipid rafts) are now recognized as critical for proper compartmentalization of insulin signaling, but their role in the pathogenesis of insulin resistance has not been investigated. Detergent-resistant membrane microdomains (DRMs), isolated in the low density fractions, are highly enriched in cholesterol, glycosphingolipids and various signaling molecules. TNFalpha induces insulin resistance in type 2 diabetes, but its mechanism of action is not fully understood. We have found a selective increase in the acidic glycosphingolipid ganglioside GM3 in 3T3-L1 adipocytes treated with TNFalpha, suggesting a specific function for GM3. We were able to extend these in vitro observations to living animals using obese Zucker fa/fa rats and ob/ob mice, in which the GM3 synthase mRNA levels in the white adipose tissues are significantly higher than in their lean controls. In the DRMs from TNFalpha-treated 3T3-L1 adipocytes, GM3 levels were doubled, compared to results in normal adipocytes. Additionally, insulin receptor (IR) accumulations in the DRMs were diminished, while caveolin and flotillin levels were unchanged. GM3 depletion was able to counteract the TNFalpha-induced inhibition of IR accumulation into DRMs. Together, these findings provide compelling evidence that in insulin resistance the insulin metabolic signaling defect can be attributed to a loss of IRs in the microdomains due to an accumulation of GM3.
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Affiliation(s)
- Jin-ichi Inokuchi
- Division of Glycopathology and CREST, Japan Science and Technology Agency, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai, Japan.
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26
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Visigalli R, Barilli A, Bussolati O, Sala R, Gazzola GC, Parolari A, Tremoli E, Simon A, Closs EI, Dall'Asta V. Rapamycin stimulates arginine influx through CAT2 transporters in human endothelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1479-87. [PMID: 17397797 DOI: 10.1016/j.bbamem.2007.02.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 01/25/2007] [Accepted: 02/15/2007] [Indexed: 01/03/2023]
Abstract
In endothelial cells Tumor Necrosis Factor-alpha (TNFalpha) stimulates arginine transport through the increased expression of SLC7A2/CAT2 transcripts. Here we show that also rapamycin, an inhibitor of mTOR kinase, stimulates system y(+)-mediated arginine uptake in human endothelial cells derived from either saphenous (HSVECs) or umbilical veins (HUVECs). When used together with TNFalpha, rapamycin produces an additive stimulation of arginine transport in both cell models. These effects are observed also upon incubation with AICAR, a stimulator of Adenosine-Monophosphate-dependent-Protein Kinase (AMPK) that produces a rapamycin-independent inhibition of the mTOR pathway. Rapamycin increases the V(max) of high affinity arginine transport and causes the appearance of a low affinity component that is particularly evident if the treatment is carried out in the presence of TNFalpha. RT-qPCR studies have demonstrated that these kinetic changes correspond to the induction of both the high affinity transporter CAT2B and the low affinity isoform CAT2A. Western blot and immunocytochemical analyses indicate that, consistently, the expression of CAT2 proteins is also stimulated under the same conditions. These changes are associated with an increase of the intracellular arginine concentration but with a decrease of NO production. Thus, our data suggest that mTOR activity is associated with the repression of CAT2 expression at mRNA and protein level.
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Affiliation(s)
- Rossana Visigalli
- Department of Experimental Medicine, Unit of General and Clinical Pathology, University of Parma, via Volturno 39, 43100 Parma, Italy
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27
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Floyd ZE, Segura BM, He F, Stephens JM. Degradation of STAT5 proteins in 3T3-L1 adipocytes is induced by TNF-{alpha} and cycloheximide in a manner independent of STAT5A activation. Am J Physiol Endocrinol Metab 2007; 292:E461-8. [PMID: 16985255 DOI: 10.1152/ajpendo.00334.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine that has been implicated as a causative factor in obesity-linked insulin resistance. It is commonly accepted that macrophage-derived TNF-alpha acts in a paracrine manner on adjacent adipocytes to inhibit the expression of various adipocyte genes and to attenuate insulin signaling. Several studies have revealed that signal transducer and activator of transcription (STAT)5 proteins are modulated during adipogenesis and can modulate the transcription of some adipocyte genes. In this study, we demonstrate that TNF-alpha treatment, in the presence of cycloheximide, also results in the rapid turnover of STAT5A and STAT5B in a process that is independent of STAT5 activation by tyrosine phosphorylation. In addition, STAT5B is more labile than STAT5A under these conditions, suggesting that the COOH terminus of STAT5 may be involved in the turnover of each protein. Initial characterization of the TNF-alpha and cycloheximide-mediated degradation of STAT5 indicates that inhibition of the proteasome stabilizes both forms of STAT5 in the presence of TNF-alpha. In addition, the use of an NF-kappaB inhibitor results in the stabilization of STAT5A in the presence of TNF-alpha and cycloheximide, indicating that the degradation of STAT5 proteins under these conditions may involve the NF-kappaB pathway. STAT5 proteins are abundantly expressed in mature adipocytes and are normally extremely stable proteins under a wide range of conditions. However, our results demonstrate that the potentiation of TNF-alpha-mediated signaling in the presence of cyclohexmide is associated with a significant increase in the degradation of STAT5 proteins in 3T3-L1 adipocytes.
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Affiliation(s)
- Z Elizabeth Floyd
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA
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Gupta D, Varma S, Khandelwal RL. Long-term effects of tumor necrosis factor-α treatment on insulin signaling pathway in HepG2 cells and HepG2 cells overexpressing constitutively active Akt/PKB. J Cell Biochem 2007; 100:593-607. [PMID: 16960890 DOI: 10.1002/jcb.21080] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) mediated attenuation of insulin signaling pathway is an important cause in several disorders like obesity, obesity linked diabetes mellitus. TNF-alpha actions vary depending upon concentration and time of exposure in various cells. In the present study, the effects of long-term TNF-alpha (1 ng/ml) exposure on the components of insulin signaling pathway in HepG2 and HepG2 cells overexpressing constitutively active Akt1/PKB-alpha (HepG2-CA-Akt/PKB) have been investigated. In parental HepG2 cells, TNF-alpha treatment for 24 h reduced the phosphorylation of Akt1/PKB-alpha and GSK-3beta and under these conditions cells also showed reduced insulin responsiveness in terms of Akt1/PKB-alpha and GSK-3beta phosphorylation. TNF-alpha pre-incubated HepG2-CA-Akt/PKB cells showed lower reduction in Akt1/PKB-alpha and GSK-3beta phosphorylation and insulin responsiveness after 24 h as compared to parental HepG2 cells. We report that the long-term TNF-alpha pre-incubation in both parental HepG2 and HepG2-CA-Akt/PKB-alpha cells leads to the reduction in the levels of IRS-1 without altering the levels of IRS-2. In order to understand the reason for the differential insulin resistance in both the cell types, the effect of long-term TNF-alpha treatment on the proteins upstream to Akt/PKB was investigated. TNF-alpha pre-incubation also showed reduced insulin-stimulated Tyr phosphorylation of insulin receptor (IR-beta) in both the cell types, moreover hyperphosphorylation of IRS-1 at Ser 312 residue was observed in TNF-alpha pre-incubated cells. As hyperphosphorylation of IRS-1 at Ser 312 can induce its degradation, it is possible that reduced insulin responsiveness after long-term TNF-alpha pre-incubation observed in this study is due to the decrease in IRS-1 levels.
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Affiliation(s)
- Dhananjay Gupta
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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29
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Abstract
Membrane microdomains (lipid rafts) are now recognized as critical for proper compartmentalization of insulin signaling, but their role in the pathogenesis of insulin resistance has not been investigated. Detergent-resistant membrane microdomains (DRMs), isolated in the low density fractions, are highly enriched in cholesterol, glycosphingolipids and various signaling molecules. TNFalpha induces insulin resistance in type 2 diabetes, but its mechanism of action is not fully understood. We have found a selective increase in the acidic glycosphingolipid ganglioside GM3 in 3T3-L1 adipocytes treated with TNFalpha, suggesting a specific function for GM3. We were able to extend these in vitro observations to living animals using obese Zucker fa/fa rats and ob/ob mice, in which the GM3 synthase mRNA levels in the white adipose tissues are significantly higher than in their lean controls. In the DRMs from TNFalpha-treated 3T3-L1 adipocytes, GM3 levels were doubled, compared to results in normal adipocytes. Additionally, insulin receptor (IR) accumulations in the DRMs were diminished, while caveolin and flotillin levels were unchanged. GM3 depletion was able to counteract the TNFalpha-induced inhibition of IR accumulation into DRMs. Together, these findings provide compelling evidence that in insulin resistance the insulin metabolic signaling defect can be attributed to a loss of IRs in the microdomains due to an accumulation of GM3.
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Affiliation(s)
- Jin-ichi Inokuchi
- Department of Biomembrane and Biofunctional Chemistry and CREST, Japan Science and Technology Agency, Graduate School of Pharmaceutical Sciences, Hokkaido University, Japan.
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Inokuchi JI. Membrane microdomain malfunction and insulin resistance in type 2 diabetes. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.11.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Yamada T, Ozaki N, Kato Y, Miura Y, Oiso Y. Insulin downregulates angiopoietin-like protein 4 mRNA in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2006; 347:1138-44. [PMID: 16870142 DOI: 10.1016/j.bbrc.2006.07.032] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Accepted: 07/09/2006] [Indexed: 10/24/2022]
Abstract
Angiopoietin-like protein 4 (angptl4) is mainly secreted from adipose tissue and inhibits lipoprotein lipase activity. The expression and plasma levels of angptl4 are increased by fasting. To clarify its regulation in diabetes and metabolic syndrome, we investigated the effect of insulin on angptl4 mRNA expression in 3T3-L1 adipocytes by using quantitative real-time PCR. Insulin suppressed angptl4 mRNA expression in time- and dose-dependent manners, and the inhibitory effect was attenuated by a RNA synthesis inhibitor actinomycin D and a phosphoinositide 3-kinase (PI3K) inhibitor LY294002. Adenoviral-mediated overexpression of forkhead transcription factor Foxo1 increased angptl4 mRNA expression, and insulin significantly suppressed its effect. In addition, insulin failed to decrease angptl4 mRNA expression in an insulin-resistant state induced by TNF-alpha in 3T3-L1 adipocytes. These results suggest that insulin downregulates angptl4 mRNA expression via PI3K/Foxo1 pathway in 3T3-L1 adipocytes, and that the reduction of angptl4 mRNA by insulin is attenuated in insulin resistance.
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Affiliation(s)
- Tsutomu Yamada
- Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Kralisch S, Klein J, Lossner U, Blüher M, Paschke R, Stumvoll M, Fasshauer M. Plasminogen activator inhibitor-1 expression and secretion are stimulated by growth hormone and interleukin-6 in 3T3-L1 adipocytes. Mol Cell Endocrinol 2006; 253:56-62. [PMID: 16713670 DOI: 10.1016/j.mce.2006.04.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 04/21/2006] [Accepted: 04/27/2006] [Indexed: 11/26/2022]
Abstract
Various adipocytokines have been described which influence insulin sensitivity and vascular function profoundly and might, therefore, potentially link obesity, insulin resistance, and atherosclerosis. Among those, plasminogen activator inhibitor (PAI)-1 is an adipose-secreted factor upregulated in obesity and insulin resistance that inhibits fibrinolysis. Furthermore, recent studies in knockout mice suggest that PAI-1 directly impairs insulin sensitivity. In the current study, the impact of growth hormone (GH) and interleukin (IL)-6 on PAI-1 mRNA synthesis and secretion was determined in 3T3-L1 adipocytes. Interestingly, 500 ng/ml GH and 30 ng/ml IL-6 increased PAI-1 secretion five-fold and 3.6-fold, respectively. Furthermore, GH and IL-6 induced PAI-1 mRNA by up to 7.3-fold, and 3.6-fold, respectively, in a time-dependent fashion with significant stimulation seen at concentrations as low as 5 ng/ml GH and 10 ng/ml IL-6. Other insulin resistance-inducing hormones which stimulated PAI-1 synthesis included insulin, TNFalpha, and dexamethasone. Studies using pharmacological inhibitors suggested that basal and GH-induced PAI-1 synthesis were at least in part mediated by p44/42 mitogen-activated protein kinase but not janus kinase 2 and phosphatidylinositol 3-kinase. Taken together, our results show a differential regulation of PAI-1 mRNA by insulin resistance-inducing hormones including GH and IL-6.
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Affiliation(s)
- Susan Kralisch
- University of Leipzig, Department of Internal Medicine III, Ph.-Rosenthal-Str. 27, 04103 Leipzig, Germany
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33
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Ijzerman RG, Voordouw JJ, Van Weissenbruch MM, Yudkin JS, Serné EH, Delemarre-van de Waal HA, Stehouwer CDA. TNF-α levels are associated with skin capillary recruitment in humans: a potential explanation for the relationship between TNF-α and insulin resistance. Clin Sci (Lond) 2006; 110:361-8. [PMID: 16316318 DOI: 10.1042/cs20050314] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The mechanism by which TNF-α (tumour necrosis factor-α) may cause insulin resistance is not clear. On the basis of experiments in rats, TNF-α has been suggested to cause defects in capillary function, with a decreased access of insulin and glucose to tissues. To test this hypothesis in humans, we assessed serum TNF-α concentrations, skin capillary recruitment and insulin sensitivity in a group of 37 healthy adults. In addition, we measured these variables in 21 of their prepubertal children. Serum TNF-α levels were measured by sandwich enzyme immunoassay, and insulin sensitivity was assessed with the hyperinsulinaemic euglycaemic clamp technique. Capillary recruitment during post-occlusive reactive hyperaemia was evaluated by videomicroscopy. In the adults, serum TNF-α levels were associated with both capillary recruitment (r=−0.40, P=0.02) and insulin sensitivity (r=−0.33, P=0.05). In addition, capillary recruitment was associated with insulin sensitivity (r=0.34, P=0.04). Regression analysis showed that the association between TNF-α and insulin sensitivity [−0.527 mg·kg−1 of body weight·min−1 per pmol/l per pg/ml TNF-α (95% confidence interval, −1.066 to 0.011); P=0.05] decreased by 30% after adjustment for capillary recruitment. In the children, neither capillary recruitment (r=0.33, P=0.2) nor insulin sensitivity (r=−0.24, P=0.4) was significantly associated with TNF-α. In conclusion, in adults, but not in children, serum TNF-α levels are associated with capillary recruitment during post-occlusive hyperaemia, which, in part, can explain the relationship between TNF-α and insulin resistance. Our data suggest that these relationships are initiated during growth from childhood to adulthood.
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Affiliation(s)
- Richard G Ijzerman
- Department of Internal Medicine, Institute for Cardiovascular Research-Vrije Universiteit, VU University Medical Center, De Boelelaan 1117, 1007 MB Amsterdam, The Netherlands
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Giordano A, Avellino R, Ferraro P, Romano S, Corcione N, Romano MF. Rapamycin antagonizes NF-kappaB nuclear translocation activated by TNF-alpha in primary vascular smooth muscle cells and enhances apoptosis. Am J Physiol Heart Circ Physiol 2006; 290:H2459-65. [PMID: 16428340 DOI: 10.1152/ajpheart.00750.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Several lines of evidence support the view that rapamycin inhibits NF-kappaB. TNF-alpha, a potent inducer of NF-kappaB, is released after artery injury (e.g., balloon angioplasty) and plays an important role in inflammation and restenosis. We investigated the effect of rapamycin on NF-kappaB activation and apoptosis in vascular smooth muscle cells (VSMCs) stimulated with TNF-alpha. Using EMSA, we found that TNF-alpha caused NF-kappaB nuclear translocation in VSMCs after 1 h of incubation. Rapamycin inhibited IkappaBalpha degradation, thereby preventing nuclear translocation. Activation of NF-kappaB was accompanied by an increase of Bcl-xL and Bfl-1/A1 proteins, detected by Western blot assay, whereas rapamycin prevented the TNF-alpha-induced enhancement of these antiapoptotic proteins. The extent of apoptosis of VSMCs exposed to TNF-alpha was significantly enhanced by rapamycin. The effect of rapamycin appeared to be independent of the phosphatidylinositol 3-kinase/Akt-protein kinase B survival pathway, because the phosphatidylinositol 3-kinase inhibitor wortmannin neither prevented IkappaBalpha degradation nor increased apoptosis of cells incubated with TNF-alpha. Finally, we demonstrate that the large immunophilin FK-506 binding protein FKBP51 is essential for TNF-alpha-induced NF-kappaB activation in VSMCs. Our findings show that rapamycin inhibits NF-kappaB activation and acts in concert with TNF-alpha in induction of VSMC apoptosis.
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Affiliation(s)
- Arturo Giordano
- Department of Biochemistry and Medical Biotechnology, University of Naples Federico II, via S. Pansini 5, 80131 Naples, Italy
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Grohmann M, Stewart C, Welsh G, Hunt L, Tavaré J, Holly J, Shield J, Sabin M, Crowne E. Site-specific differences of insulin action in adipose tissue derived from normal prepubertal children. Exp Cell Res 2005; 308:469-78. [PMID: 15936753 DOI: 10.1016/j.yexcr.2005.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 05/03/2005] [Accepted: 05/06/2005] [Indexed: 01/22/2023]
Abstract
Body fat distribution determines obesity-related morbidity in adults but little is known of the aetiology or pathophysiology in children. This study investigates differences in insulin-mediated metabolism in primary cell cultures of subcutaneous and visceral preadipocytes derived from prepubertal children. The impact of differentiation and responses to TNFalpha exposure was also investigated. Proliferation rates were greater in subcutaneous versus visceral preadipocytes (41 h3 versus 69 h4; P=0.008). Insulin caused a dose-dependent increase in GSK-3 phosphorylation and an increase in MAPK phosphorylation over time, with increased sensitivity in subcutaneous preadipocytes. Post-differentiation, dose-dependent increases in GSK-3 phosphorylation were maintained, while MAPK phosphorylation was identical in both subtypes. No changes were observed in insulin receptor abundance pre-/post-differentiation. GLUT4 abundance was significantly increased in visceral versus subcutaneous adipocytes by 76(4)%; P=0.03), coincidental with increased insulin-stimulated 2-deoxy-glucose transport (+150(26)% versus +79(10)%; P=0.014) and further elevated by acute exposure to TNFalpha (+230(52)%; P=0.019 versus +123(24)%; P=0.025, respectively). TNFalpha also significantly increased basal glucose transport rates (+44(14)%; P=0.006 versus +34(11)%; P=0.007) and GLUT1 localisation to the plasma membrane. These data establish site-specific differences in subcutaneous and visceral fat cells from children. Responses to insulin varied with differentiation and TNFalpha exposure in the two depots, consistent with parallel changes in GLUT1/4 abundance and localisation.
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Affiliation(s)
- Malcolm Grohmann
- Department of Surgery, University of Bristol, Bristol Royal Infirmary, Upper Maudlin Street, Bristol, UK
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36
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Medina EA, Afsari RR, Ravid T, Castillo SS, Erickson KL, Goldkorn T. Tumor necrosis factor-{alpha} decreases Akt protein levels in 3T3-L1 adipocytes via the caspase-dependent ubiquitination of Akt. Endocrinology 2005; 146:2726-35. [PMID: 15746249 DOI: 10.1210/en.2004-1074] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TNF-alpha is a mediator of insulin resistance in sepsis, obesity, and type 2 diabetes and is known to impair insulin signaling in adipocytes. Akt (protein kinase B) is a crucial signaling mediator for insulin. In the present study we examined the posttranslational mechanisms by which short-term (<6-h) exposure of 3T3-L1 adipocytes to TNF-alpha decreases Akt levels. TNF-alpha treatment both increased the ubiquitination of Akt and decreased its protein level. The decrease in protein was associated with the presence of an (immunoreactive) Akt fragment after TNF-alpha treatment, indicative of Akt cleavage. The broad-spectrum caspase inhibitor t-butoxycarbonyl-Asp(O-Me)-fluoromethyl ketone markedly suppressed these effects of TNF-alpha. The caspase-6 inhibitor Z-Val-Glu(OMe)-Ile-Asp(OMe)-CH(2)F potently suppressed Akt ubiquitination, degradation, and fragment formation, whereas the proteasome inhibitor Z-Leu-Leu-Leu-CHO modestly attenuated the decline in Akt levels. Exposure to TNF-alpha also enhanced the association of Akt with an E3 ligase activity. Adipocytes preexposed to TNF-alpha for 5 h and then stimulated with insulin for 30 min exhibited decreased levels of Akt, phosphorylated Akt, as well as phosphorylated Mdm2, which is a known direct substrate of Akt, and glucose uptake. Caspase inhibition attenuated these inhibitory effects of TNF-alpha. Collectively, our results suggest that TNF-alpha induces the caspase-dependent degradation of Akt via the cleavage and ubiquitination of Akt, which results in its degradation through the 26S proteasome. Furthermore, the caspase- and proteasome-mediated degradation of Akt due to TNF-alpha exposure leads to impaired Akt-dependent insulin signaling in adipocytes. These findings expand the mechanism by which TNF-alpha impairs insulin signaling.
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Affiliation(s)
- Edward A Medina
- Signal Transduction, Department of Internal Medicine, University of California School of Medicine, 6510 Genome and Bioscience Facility Building, 451 East Health Sciences Drive, Davis, California 95616, USA
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Kokta TA, Dodson MV, Gertler A, Hill RA. Intercellular signaling between adipose tissue and muscle tissue. Domest Anim Endocrinol 2004; 27:303-31. [PMID: 15519037 DOI: 10.1016/j.domaniend.2004.05.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2003] [Accepted: 05/12/2004] [Indexed: 11/22/2022]
Abstract
Adipose and muscle tissues undergo regulated growth and differentiation processes that are modulated by a wide range of factors. The interactions between myogenic cells and adipocytes play a significant role in growth and development, including the rate and extent of myogenesis, muscle growth, adipogenesis, lipogenesis/lipolysis, and in the utilization of energy substrates. Important hormones and growth factors involved in the regulation of these processes include glucocorticoids, insulin-like growth factors, various cytokines, insulin, and leptin. Interactions among these axes have important implications in their influence on relative fat and lean deposition and the efficiency of energy utilization in growth and development. As research progresses to better clarify the interactions among adipose tissue depots and muscle of different fiber types, pathways will become better understood, ultimately leading to the optimized management of fat and lean growth in domestic livestock species. This review will focus on elements of intercellular signaling, using data from cell culture studies to illustrate specific examples of signaling pathways between cells.
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Affiliation(s)
- T A Kokta
- Department of Animal and Veterinary Science, University of Idaho, 311 Agricultural Biotechnology Building, P.O. Box 442330, Moscow, ID 83844-2330, USA
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Rosenson RS, Tangney CC, Levine DM, Parker TS, Gordon BR. Elevated soluble tumor necrosis factor receptor levels in non-obese adults with the atherogenic dyslipoproteinemia. Atherosclerosis 2004; 177:77-81. [PMID: 15488868 DOI: 10.1016/j.atherosclerosis.2004.05.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Revised: 05/04/2004] [Accepted: 05/17/2004] [Indexed: 11/22/2022]
Abstract
Adipose tissue expression of tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of obesity-linked insulin resistance and the dyslipoproteinemia of insulin resistance. This study has two aims: (1) to compare select inflammatory mediators in non-smoking, normoglycemic male subjects with and without the atherogenic dyslipoproteinemia (ADL), and (2) to determine the effects of statin therapy on select inflammatory mediators. ADL subjects had higher levels of insulin (16.7 +/- 7.5 versus 11.6 +/- 5.9 microIU/mL, P=0.008), soluble TNF receptor superfamily 1B (sTNFRSF1B) (3.3 +/- 0.7 versus 2.7 +/- 0.5 ng/mL, P=0.005), and interleukin-6 (IL-6) (2.6 +/- 2.2 versus 1.3 +/- 1.8 pg/mL, P=0.006) as compared to those of the non-ADL subjects. After adjustment for age, sTNFRSF1B (P=0.003) was more predictive of ADL than high-sensitivity C-reactive protein (hs-CRP) (P=0.047). Statin therapy did not change sTNFRSF1B, TNF-alpha, IL-6, hs-CRP, whereas soluble TNF receptor superfamily 1A (sTNFRSF1A) increased slightly (P=0.048). A high level of sTNFRSF1B is a strong marker of the pro-inflammatory state in this sample of male ADL subjects.
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Affiliation(s)
- Robert S Rosenson
- Department of Medicine, Division of Cardiology, Preventive Cardiology Center, The Feinberg School of Medicine, Northwestern University, 201 East Huron Street, Galter Pavilion, Suite 11-120, Chicago, IL 60611, USA.
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Wheatley CM, Rattigan S, Richards SM, Barrett EJ, Clark MG. Skeletal muscle contraction stimulates capillary recruitment and glucose uptake in insulin-resistant obese Zucker rats. Am J Physiol Endocrinol Metab 2004; 287:E804-9. [PMID: 15213062 DOI: 10.1152/ajpendo.00077.2004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exercise and insulin increase muscle glucose uptake by different mechanisms and also increase capillary recruitment, which is proposed to facilitate access for hormones and nutrients. The genetically obese Zucker rat shows impaired insulin- but not contraction-mediated glucose uptake in muscle. Recently, we have shown the genetically obese Zucker rats to have impaired insulin-mediated capillary recruitment and proposed that this contributes to the insulin resistance of muscle in vivo. Because this might imply a general loss of recruitable capillaries, we now assess responses to contraction in muscles of 18 +/- 3-wk-old lean and obese Zucker rats in vivo. Field stimulation (2 Hz, 0.1 ms) was conducted for 1 h on one leg of anesthetized instrumented rats, and measurements were made of femoral blood flow (FBF), heart rate (HR), blood pressure (BP), hindleg metabolism of 1-methylxanthine (a measure of capillary recruitment), hindleg glucose uptake (HGU), and lower leg muscle glucose uptake by 2-deoxyglucose (R'g). Lean animals (311 +/- 9 g) developed tension at 219 +/- 27 g/g muscle with no change in BP but with significant increases in HR, FBF, HGU, 1-MX metabolism, and R'g (P < 0.05), compared with nonstimulated control leans. Obese animals (469 +/- 7 g) developed tension at 265 +/- 31 g/g muscle with no change in HR or BP but with significant increases in FBF, HGU, 1-MX metabolism, and R'g (P < 0.05) compared with nonstimulated control obese rats. Muscle contraction of lean animals led to a greater increase in lower leg R'g, similar responses in HGU and 1-MX, and a smaller increase in FBF than in obese animals. A tight correlation between FBF and capillary recruitment was noted for all data (P < 0.001). It is concluded that contraction-mediated muscle capillary recruitment and glucose uptake are essentially normal in the obese Zucker rat and that control of FBF and capillary recruitment in exercise is closely linked.
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Affiliation(s)
- Catherine M Wheatley
- Department of Biochemistry, Medical School, University of Tasmania, Hobart, Australia, 7001
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40
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Gupta D, Khandelwal RL. Modulation of insulin effects on phosphorylation of protein kinase B and glycogen synthesis by tumor necrosis factor-α in HepG2 cells. Biochim Biophys Acta Gen Subj 2004; 1671:51-8. [PMID: 15026145 DOI: 10.1016/j.bbagen.2004.01.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Revised: 01/07/2004] [Accepted: 01/09/2004] [Indexed: 02/08/2023]
Abstract
The effects of tumor necrosis factor-alpha (TNF-alpha) on insulin-induced phosphorylation of protein kinase B-alpha (PKB-alpha) and downstream enzyme glycogen synthase kinase-3 beta (GSK-3 beta) was examined in HepG2 liver cells. The exogenous treatment of HepG2 cells with TNF-alpha for 1 h caused phosphorylation of Ser473 and Thr308 residues of PKB-alpha. The maximal phosphorylation (approximately 4-fold) was obtained with 1 ng/ml TNF-alpha and no further increase was observed with higher concentrations of this cytokine. The cells pretreated with TNF-alpha for 1 h followed by incubation with insulin (10 nM) showed near additive effect on phosphorylation of PKB-alpha and downstream enzyme GSK-3 beta. The long-term (4, 8, 24 h) exogenous treatment of cells with optimal (1 ng/ml) concentration of TNF-alpha also caused phosphorylation of PKB-alpha, albeit to a lesser degree. However, long-term pretreatments of cells with TNF-alpha reduced insulin-stimulated phosphorylation of PKB-alpha and GSK-3 beta. Short- and long-term preincubation of HepG2 cells with TNF-alpha also resulted in parallel changes in glycogen synthesis in the presence of insulin. In fact, long-term preincubation with TNF-alpha completely abolished the insulin-induced glycogen synthesis. These results suggest that short-term exposure to TNF-alpha augments insulin effects whereas long-term exposure causes insulin resistance in HepG2 cells.
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Affiliation(s)
- Dhananjay Gupta
- Department of Biochemistry, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada, S7N 5E5
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Kim S, Domon-Dell C, Kang J, Chung DH, Freund JN, Evers BM. Down-regulation of the tumor suppressor PTEN by the tumor necrosis factor-alpha/nuclear factor-kappaB (NF-kappaB)-inducing kinase/NF-kappaB pathway is linked to a default IkappaB-alpha autoregulatory loop. J Biol Chem 2004; 279:4285-91. [PMID: 14623898 DOI: 10.1074/jbc.m308383200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PTEN (phosphatase and tensin homolog deleted on chromosome ten) tumor suppressor gene affects multiple cellular processes including cell growth, proliferation, and cell migration by antagonizing phosphatidylinositol 3-kinase (PI3K). However, mechanisms by which PTEN expression is regulated have not been studied extensively. Similar to PTEN, tumor necrosis factor-alpha (TNF-alpha) affects a wide spectrum of diseases including inflammatory processes and cancer by acting as a mediator of apoptosis, inflammation, and immunity. In this study, we show that treatment of cancer cell lines with TNF-alpha decreases PTEN expression. In addition, overexpression of TNF-alpha downstream signaling targets, nuclear factor-kappaB (NF-kappaB)-inducing kinase (NIK) and p65 nuclear factor NF-kappaB, lowers PTEN expression, suggesting that TNF-alpha-induced down-regulation of PTEN is mediated through a TNF-alpha/NIK/NF-kappaB pathway. Down-regulation of PTEN by NIK/NF-kappaB results in activation of the PI3K/Akt pathway and augmentation of TNF-alpha-induced PI3K/Akt stimulation. Importantly, we demonstrate that this effect is associated with a lack of an inhibitor of kappaB (IkappaB)-alpha autoregulatory loop. Moreover, these findings suggest the interaction between PI3K/Akt and NF-kappaB via transcriptional regulation of PTEN and offer one possible explanation for increased tumorigenesis in systems in which NF-kappaB is chronically activated. In such a tumor system, these findings suggest a positive feedback loop whereby Akt activation of NF-kappaB further stimulates Akt via down-regulation of the PI3K inhibitor PTEN.
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Affiliation(s)
- Sunghoon Kim
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas 77555-0536, USA
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42
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Zhang L, Wheatley CM, Richards SM, Barrett EJ, Clark MG, Rattigan S. TNF-alpha acutely inhibits vascular effects of physiological but not high insulin or contraction. Am J Physiol Endocrinol Metab 2003; 285:E654-60. [PMID: 12759220 DOI: 10.1152/ajpendo.00119.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TNF-alpha is elevated in many states of insulin resistance, and acutely administered TNF-alpha in vivo inhibits insulin-mediated hemodynamic effects and glucose uptake in muscle. In this study, we assess whether the inhibitory effects of TNF-alpha are affected by insulin dose or muscle contraction. Whole body glucose infusion rate (GIR), femoral blood flow (FBF), hindleg vascular resistance, hindleg glucose uptake (HGU), 2-deoxyglucose uptake into muscles of the lower leg (R'g) and hindleg metabolism of infused 1-methylxanthine (1-MX), a measure of capillary recruitment, were determined. Three groups were studied with and without infusion of TNF-alpha: euglycemic insulin-clamped, one-leg field-stimulated (2 Hz, 0.1 ms at 30 V), and saline-infused control anesthetized rats. Insulin infusions were 3, 10, or 30 mU x kg-1 x min-1 for 2 h x 1-MX metabolism was maximally increased by all three doses of insulin. GIR, HGU, and R'g were maximal at 10 mU and FBF was maximal at 30 mU of insulin. Contraction increased FBF, HGU, and 1-MX. TNF-alpha (0.5 microg x kg-1 x h-1) totally blocked the 3 and 10 mU insulin-mediated increases in FBF and 1-MX, and partly blocked GIR, HGU, and R'g. None of the increases due to twitch contraction was affected by TNF-alpha, and only the increase in FBF due to 30 mU of insulin was partly affected. We conclude that muscle capillary recruitment and glucose uptake due to high levels of insulin or muscle contraction under twitch stimuli at 2 Hz are resistant to TNF-alpha. These findings may have implications for ameliorating muscle insulin resistance resulting from increased plasma TNF-alpha and for the differing mechanisms by which contraction and insulin recruit capillary flow in muscle.
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Affiliation(s)
- Lei Zhang
- Department of Biochemistry, University of Tasmania, Hobart 7001, Australia
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43
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Wiedmann M, Tamaki S, Silberman R, de la Monte SM, Cousens L, Wands JR. Constitutive over-expression of the insulin receptor substrate-1 causes functional up-regulation of Fas receptor. J Hepatol 2003; 38:803-10. [PMID: 12763374 DOI: 10.1016/s0168-8278(03)00117-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND/AIMS Insulin- and insulin growth factor-1 stimulated signaling through the insulin receptor substrate-1 (IRS-1) promotes hepatocellular proliferation and survival. IRS-1 over-expression in transgenic (Tg) mouse livers caused constitutive activation of Erk mitogen activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K) resulting in significantly increased levels of DNA synthesis and larger hepatic masses relative to non-transgenic (non-Tg) littermates. However, the livers eventually ceased to grow but remained approximately 25% larger than non-Tg livers. We hypothesized that this growth homeostasis was achieved by parallel activation of pro-apoptosis pathways. METHODS Since Fas-mediated apoptosis is a common mechanism of hepatocyte destruction, we investigated the potential role of Fas receptor as a regulator of hepatic mass in IRS-1 transgenic mice. RESULTS Significantly increased Fas-receptor levels were detected in the livers of IRS-1 Tg compared to non-Tg mice by Western blot analysis. Functional activation of Fas-receptor in IRS-1 Tg livers was demonstrated by increased hepatocellular apoptosis caused by intravenous injection of anti-Fas (Jo-2). CONCLUSIONS These findings suggest that the increased growth caused by IRS-1 over-expression is balanced by constitutive activation of pro-death mechanisms. Failure of the IRS-1 Tg mice to develop liver cancer may be due to preservation of pro-growth, pro-death homeostasis mechanisms.
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Affiliation(s)
- Marcus Wiedmann
- Department of Medicine, Liver Research Center, Rhode Island Hospital, Brown University School of Medicine, 55 Claverick Street 4th floor, Providence, RI 02903, USA
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44
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Wybrańska I, Malczewska-Malec M, Niedbał S, Naskalski JW, Dembińska-Kieć A. The TNF-alpha gene NcoI polymorphism at position -308 of the promoter influences insulin resistance, and increases serum triglycerides after postprandial lipaemia in familiar obesity. Clin Chem Lab Med 2003; 41:501-10. [PMID: 12747594 DOI: 10.1515/cclm.2003.076] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Tumour necrosis factor alpha (TNF-alpha), acting as a modulator of gene expression in adipocytes, has been linked to the development of insulin resistance and obesity. The aim of this study was to investigate whether the A/G variation at position -308 in the TNF-alpha promoter influences the body weight, insulin resistance, and postprandial lipaemia in Polish Caucasians. One hundred twenty one subjects, 38 men and 83 women, representing 40 obese families, were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). TNF-1 (GG) and TNF-2 (GA and AA) allele carriers were compared with respect to body mass index, fat/lean body mass composition, waist-to-hip ratio, as well as fasting lipids, glucose, leptin, and insulin fasting, and during the oral glucose tolerance test (4 points within 2 hours) and oral lipid tolerance test (OLTT; 5 points within 8 hours). The insulin sensitivity indices HOMA-IR (homeostasis model assessment of insulin resistance), ISI-COMP (whole body insulin sensitivity index), ISI-HOMA (hepatic insulin sensitivity), and DELTA (early secretory response to an oral glucose load) were calculated. We detected 64 GG, 56 GA, and 1 AA genotypes. Significant increases of insulin resistance parameters in obese female TNF-2 allele carriers were observed (significantly increased HOMA-IR and decreased ISI-HOMA, ISI-composite). The male TNF-2 carriers were characterised by significantly increased levels of triglyceride and free fatty acids during OLTT as well as fasting glucose. The A/G variation at position -308 in the promoter region of the TNF-alpha gene could be an important genetic factor predisposing to insulin resistance in obese women and increased levels of glucose, triglyceride, and free fatty acids in men.
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Affiliation(s)
- Iwona Wybrańska
- Department of Clinical Biochemistry, The Jagiellonian University Medical College, Kraków, Kopernika, Poland.
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45
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Mei J, Wang CN, O'Brien L, Brindley DN. Cell-permeable ceramides increase basal glucose incorporation into triacylglycerols but decrease the stimulation by insulin in 3T3-L1 adipocytes. Int J Obes (Lond) 2003; 27:31-9. [PMID: 12532151 DOI: 10.1038/sj.ijo.0802183] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2002] [Revised: 07/10/2002] [Accepted: 07/16/2002] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To investigate mechanisms for the regulation of glucose incorporation into triacylgycerols in adipocytes by ceramides, which mediate some actions of tumour necrosis factor-alpha (TNFalpha). DESIGN The effects of C(2)- and C(6)-ceramides (N-acetyl- and N-hexanoyl-sphingosines, respectively) on glucose uptake and incorporation into triacylglycerols and pathways of signal tansduction were measured in 3T3-L1 adipocytes. RESULTS C(6)-ceramide increased basal 2-deooxyglucose uptake but decreased insulin-stimulated uptake without changing the EC(50) for insulin. Incubating 3T3-L1 adipocytes from 2 to 24 h with C(2)-ceramide progressively increased glucose incorporation into the fatty acid and especially the glycerol moieties of triacylglycerol. These effects were accompanied by increased GLUT1 synthesis resulting from ceramide-induced activation phosphatidylinositol 3-kinase, ribosomal S6 kinase and mitogen-activated protein kinase. C(2)-ceramide also increased p21-activated kinase and protein kinase B activities. However, C(2)-ceramide decreased the insulin-stimulated component of these signalling pathways and also glucose incorporation into triacylglycerol after 2 h. CONCLUSIONS Cell-permeable ceramides can mimic some effects of TNFalpha in producing insulin resistance. However, ceramides also mediate long-term effects that enable 3T3 L1 adipocytes to take up glucose and store triacylglycerols in the absence of insulin. These observations help to explain part of the nature and consequence of TNFalpha-induced insulin resistance and the control of fat accumulation in adipocytes in insulin resistance and obesity.
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Affiliation(s)
- J Mei
- Department of Biochemistry (Signal Transduction Research Group), University of Alberta, Edmonton, Alberta, Canada
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46
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Blagoev B, Kratchmarova I, Nielsen MM, Fernandez MM, Voldby J, Andersen JS, Kristiansen K, Pandey A, Mann M. Inhibition of adipocyte differentiation by resistin-like molecule alpha. Biochemical characterization of its oligomeric nature. J Biol Chem 2002; 277:42011-6. [PMID: 12189153 DOI: 10.1074/jbc.m206975200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel family of cysteine-rich secreted proteins with unique tissue distribution has recently been identified. One of the members, resistin (for "resistance to insulin"), also called FIZZ3, was identified in a screen for molecules that are down-regulated in mature adipocytes upon administration of thiazolidinediones. The prototypical member of this family was originally identified from bronchoalveolar lavage fluid of inflamed lungs and designated FIZZ1 ("found in inflammatory zone"). This molecule was also found to be highly expressed in adipose tissue and was named resistin-like molecule alpha (RELMalpha). Here we demonstrate that RELMalpha inhibits the differentiation of 3T3-L1 preadipocytes into adipocytes. RELMalpha has no effect on proliferation of 3T3-L1 preadipocytes. Pretreatment of 3T3-L1 preadipocytes with RELMalpha does not affect insulin- or platelet-derived growth factor-induced mitogenesis. IRS-1 phosphorylation and glucose transport stimulated by insulin in mature adipocytes were also unaffected by RELMalpha. We show that RELMalpha forms disulfide-linked homooligomers based on results from electrophoresis under reducing and nonreducing conditions, coimmunoprecipitation experiments as well as by mass spectrometry. In addition, RELMalpha is able to form heterooligomers with resistin but not RELMbeta. Since RELMalpha is expressed by adipose tissue and it is a secreted factor, our findings suggest that RELMalpha may be involved in the control of the adipogenesis as well as in the process of muscle differentiation.
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Affiliation(s)
- Blagoy Blagoev
- Center for Experimental Bioinformatics, University of Southern Denmark, Odense M DK-5230, Denmark
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47
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Hanna AN, Xu J, Brindley DN. Tumor necrosis factor-alpha, sphingomyelinase and ceramides activate tyrosine kinase, p21Ras and phosphatidylinositol 3-kinase: implications for glucose transport and insulin resistance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 498:191-200. [PMID: 11900368 DOI: 10.1007/978-1-4615-1321-6_25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Affiliation(s)
- A N Hanna
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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48
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Ruan H, Hacohen N, Golub TR, Van Parijs L, Lodish HF. Tumor necrosis factor-alpha suppresses adipocyte-specific genes and activates expression of preadipocyte genes in 3T3-L1 adipocytes: nuclear factor-kappaB activation by TNF-alpha is obligatory. Diabetes 2002; 51:1319-36. [PMID: 11978627 DOI: 10.2337/diabetes.51.5.1319] [Citation(s) in RCA: 390] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is a contributing cause of the insulin resistance seen in obesity and obesity-linked type 2 diabetes, but the mechanism(s) by which TNF-alpha induces insulin resistance is not understood. By using 3T3-L1 adipocytes and oligonucleotide microarrays, we identified 142 known genes reproducibly upregulated by at least threefold after 4 h and/or 24 h of TNF-alpha treatment, and 78 known genes downregulated by at least twofold after 24 h of TNF-alpha incubation. TNF-alpha-induced genes include transcription factors implicated in preadipocyte gene expression or NF-kappaB activation, cytokines and cytokine-induced proteins, growth factors, enzymes, and signaling molecules. Importantly, a number of adipocyte-abundant genes, including GLUT4, hormone sensitive lipase, long-chain fatty acyl-CoA synthase, adipocyte complement-related protein of 30 kDa, and transcription factors CCAAT/enhancer binding protein-alpha, receptor retinoid X receptor-alpha, and peroxisome profilerator-activated receptor gamma were significantly downregulated by TNF-alpha treatment. Correspondingly, 24-h exposure of 3T3-L1 adipocytes to TNF-alpha resulted in reduced protein levels of GLUT4 and several insulin signaling proteins, including the insulin receptor, insulin receptor substrate 1 (IRS-1), and protein kinase B (AKT). Nuclear factor-kappaB (NF-kappaB) was activated within 15 min of TNF-alpha addition. 3T3-L1 adipocytes expressing IkappaBalpha-DN, a nondegradable NF-kappaB inhibitor, exhibited normal morphology, global gene expression, and insulin responses. However, absence of NF-kappaB activation abolished suppression of >98% of the genes normally suppressed by TNF-alpha and induction of 60-70% of the genes normally induced by TNF-alpha. Moreover, extensive cell death occurred in IkappaBalpha-DN-expressing adipocytes after 2 h of TNF-alpha treatment. Thus the changes in adipocyte gene expression induced by TNF-alpha could lead to insulin resistance. Further, NF-kappaB is an obligatory mediator of most of these TNF-alpha responses.
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Affiliation(s)
- Hong Ruan
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
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49
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Abstract
Phosphoinositide 3-kinases (PI3Ks) are an evolutionarily conserved family of signal transducing enzymes. A great variety of stimuli activate PI3K, leading to the transient accumulation of its lipid products in cell membranes. These lipids serve as second messengers to regulate the location and activity of an array of downstream effector molecules. In cells of the mammalian immune system, PI3K is activated by receptors for antigen, cytokines, costimulatory molecules, immunoglobulins and chemoattractants. Signaling via PI3K regulates immune cell proliferation, survival, differentiation, chemotaxis, phagocytosis, degranulation, and respiratory burst. Here we review our current understanding of PI3K signaling in leukocytes.
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Affiliation(s)
- David A Fruman
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
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50
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Tagami S, Inokuchi Ji JI, Kabayama K, Yoshimura H, Kitamura F, Uemura S, Ogawa C, Ishii A, Saito M, Ohtsuka Y, Sakaue S, Igarashi Y. Ganglioside GM3 participates in the pathological conditions of insulin resistance. J Biol Chem 2002; 277:3085-92. [PMID: 11707432 DOI: 10.1074/jbc.m103705200] [Citation(s) in RCA: 278] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Gangliosides are known as modulators of transmembrane signaling by regulating various receptor functions. We have found that insulin resistance induced by tumor necrosis factor-alpha (TNF-alpha) in 3T3-L1 adipocytes was accompanied by increased GM3 ganglioside expression caused by elevating GM3 synthase activity and its mRNA. We also demonstrated that TNF-alpha simultaneously produced insulin resistance by uncoupling insulin receptor activity toward insulin receptor substrate-1 (IRS-1) and suppressing insulin-sensitive glucose transport. Pharmacological depletion of GM3 in adipocytes by an inhibitor of glucosylceramide synthase prevented the TNF-alpha-induced defect in insulin-dependent tyrosine phosphorylation of IRS-1 and also counteracted the TNF-alpha-induced serine phosphorylation of IRS-1. Moreover, when the adipocytes were incubated with exogenous GM3, suppression of tyrosine phosphorylation of insulin receptor and IRS-1 and glucose uptake in response to insulin stimulation was observed, demonstrating that GM3 itself is able to mimic the effects of TNF on insulin signaling. We used the obese Zucker fa/fa rat and ob/ob mouse, which are known to overproduce TNF-alpha mRNA in adipose tissues, as typical models of insulin resistance. We found that the levels of GM3 synthase mRNA in adipose tissues of these animals were significantly higher than in their lean counterparts. Taken together, the increased synthesis of cellular GM3 by TNF may participate in the pathological conditions of insulin resistance in type 2 diabetes.
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Affiliation(s)
- Seiichi Tagami
- First Department of Medicine, Hokkaido University School of Medicine, Kita 15-jo, Nishi 7-chome, Kita-ku, Japan
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