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Kurita H, Ueda M, Kimura M, Okuda A, Ohuchi K, Hozumi I, Inden M. Zinc Deficiency Decreases Neurite Extension via CRMP2 Signal Pathway. Biol Pharm Bull 2024; 47:796-800. [PMID: 38583951 DOI: 10.1248/bpb.b24-00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Previous reports indicated that zinc deficiency could increase the risk of infectious diseases and developmental retardation in children. In experimental study, it has been reported that zinc deficiency during the embryonic period inhibited fetal growth, and disturbed neural differentiation and higher brain function later in adulthood. Although it has been suggested that zinc deficiency during development can have significant effects on neuronal differentiation and maturation, the molecular mechanisms of the effects of low zinc on neuronal differentiation during development have not been elucidated in detail. This study was performed to determine the effects of low zinc status on neurite outgrowth and collapsin response mediator protein 2 (CRMP2) signal pathway. Low zinc suppressed neurite outgrowth, and caused increase levels of phosphorylated CRMP2 (pCRMP2) relative to CRMP2, and decrease levels of phosphorylated glycogen synthase kinase 3β (pGSK3β) relative to GSK3β in human neuroblastoma cell line (SH-SY5Y) cells on days 1, 2, and 3 of neuronal differentiation induction. Neurite outgrowth inhibited by low zinc was restored by treatment with the GSK3β inhibitor CHIR99021. These results suggested that low zinc causes neurite outgrowth inhibition via phosphorylation of CRMP2 by GSK3β. In conclusion, this study is the first to demonstrate that CRMP signaling is involved in the suppression of neurite outgrowth by low zinc.
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Affiliation(s)
- Hisaka Kurita
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
| | - Misa Ueda
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
| | - Miyu Kimura
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
| | - Ayu Okuda
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
| | - Kazuki Ohuchi
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
| | - Isao Hozumi
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
| | - Masatoshi Inden
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University
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2
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Arad E, Yosefi G, Kolusheva S, Bitton R, Rapaport H, Jelinek R. Native Glucagon Amyloids Catalyze Key Metabolic Reactions. ACS NANO 2022; 16:12889-12899. [PMID: 35866668 DOI: 10.1021/acsnano.2c05166] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Glucagon is a prominent peptide hormone, playing central roles in the regulation of glucose blood-level and lipid metabolism. Formation of glucagon amyloid fibrils has been previously reported, although no biological functions of such fibrils are known. Here, we demonstrate that glucagon amyloid fibrils catalyze biologically important reactions, including esterolysis, lipid hydrolysis, and dephosphorylation. In particular, we found that glucagon fibrils catalyze dephosphorylation of adenosine triphosphate (ATP), a core metabolic reaction in cell biology. Comparative analysis of several glucagon variants allowed mapping the catalytic activity to an enzymatic pocket-like triad formed at the glucagon fibril surface, comprising the histidyl-serine domain at the N-terminus of the peptide. This study may point to previously unknown physiological roles and pathological consequences of glucagon fibrillation and supports the hypothesis that catalytic activities of native amyloid fibrils play functional roles in human physiology and disease.
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Affiliation(s)
- Elad Arad
- Ilse Katz Institute (IKI) for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Gal Yosefi
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Sofiya Kolusheva
- Ilse Katz Institute (IKI) for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Ronit Bitton
- Ilse Katz Institute (IKI) for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Hanna Rapaport
- Ilse Katz Institute (IKI) for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Raz Jelinek
- Ilse Katz Institute (IKI) for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
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Messersmith EM, Smerchek DT, Hansen SL. The Crossroads between Zinc and Steroidal Implant-Induced Growth of Beef Cattle. Animals (Basel) 2021; 11:1914. [PMID: 34199133 PMCID: PMC8300159 DOI: 10.3390/ani11071914] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/24/2021] [Accepted: 06/24/2021] [Indexed: 12/17/2022] Open
Abstract
Growth-promoting technologies such as steroidal implants have been utilized in the beef industry for over 60 years and remain an indispensable tool for improving economic returns through consistently improved average daily gain via increased skeletal muscle hypertrophy. Zinc has been implicated in skeletal muscle growth through protein synthesis, satellite cell function, and many other growth processes. Therefore, the objective of this review was to present the available literature linking Zn to steroidal implant-induced protein synthesis and other metabolic processes. Herein, steroidal implants and their mode of action, the biological importance of Zn, and several connections between steroidal implants and Zn related to growth processes are discussed. These include the influence of Zn on hormone receptor signaling, circulating insulin-like growth factor-1 concentrations, glucose metabolism, protein synthesis via mTOR, and satellite cell proliferation and differentiation. Supplemental Zn has also been implicated in improved growth rates of cattle utilizing growth-promoting technologies, and steroidal implants appear to alter liver and circulating Zn concentrations. Therefore, this review provides evidence of the role of Zn in steroidal implant-induced growth yet reveals gaps in the current knowledge base related to optimizing Zn supplementation strategies to best capture growth performance improvements offered through steroidal implants.
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Affiliation(s)
| | | | - Stephanie L. Hansen
- Department of Animal Science, Iowa State University, Ames, IA 50011, USA; (E.M.M.); (D.T.S.)
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4
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Vahidi Ferdowsi P, Ng R, Adulcikas J, Sohal SS, Myers S. Zinc Modulates Several Transcription-Factor Regulated Pathways in Mouse Skeletal Muscle Cells. Molecules 2020; 25:E5098. [PMID: 33153045 PMCID: PMC7663025 DOI: 10.3390/molecules25215098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 10/28/2020] [Indexed: 02/07/2023] Open
Abstract
Zinc is an essential metal ion involved in many biological processes. Studies have shown that zinc can activate several molecules in the insulin signalling pathway and the concomitant uptake of glucose in skeletal muscle cells. However, there is limited information on other potential pathways that zinc can activate in skeletal muscle. Accordingly, this study aimed to identify other zinc-activating pathways in skeletal muscle cells to further delineate the role of this metal ion in cellular processes. Mouse C2C12 skeletal muscle cells were treated with insulin (10 nM), zinc (20 µM), and the zinc chelator TPEN (various concentrations) over 60 min. Western blots were performed for the zinc-activation of pAkt, pErk, and pCreb. A Cignal 45-Reporter Array that targets 45 signalling pathways was utilised to test the ability of zinc to activate pathways that have not yet been described. Zinc and insulin activated pAkt over 60 min as expected. Moreover, the treatment of C2C12 skeletal muscle cells with TPEN reduced the ability of zinc to activate pAkt and pErk. Zinc also activated several associated novel transcription factor pathways including Nrf1/Nrf2, ATF6, CREB, EGR1, STAT1, AP-1, PPAR, and TCF/LEF, and pCREB protein over 120 min of zinc treatment. These studies have shown that zinc's activity extends beyond that of insulin signalling and plays a role in modulating novel transcription factor activated pathways. Further studies to determine the exact role of zinc in the activation of transcription factor pathways will provide novel insights into this metal ion actions.
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Affiliation(s)
| | | | | | | | - Stephen Myers
- College of Health and Medicine, School of Health Sciences, University of Tasmania, Newnham Campus, Launceston 7250, Australia; (P.V.F.); (R.N.); (J.A.); (S.S.S.)
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5
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Wu J, Tao W, Bu D, Zhao Y, Zhang T, Chong D, Xue B, Xing Z, Li C. Egr-1 transcriptionally activates protein phosphatase PTP1B to facilitate hyperinsulinemia-induced insulin resistance in the liver in type 2 diabetes. FEBS Lett 2019; 593:3054-3063. [PMID: 31309546 DOI: 10.1002/1873-3468.13537] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/26/2019] [Accepted: 07/04/2019] [Indexed: 01/14/2023]
Abstract
During the development of type 2 diabetes mellitus (T2DM), hyperinsulinemia is the earliest symptom. It is believed that long-term high insulin stimulation might facilitate insulin resistance in the liver, but the underlying mechanism remains unknown. Herein, we report that hyperinsulinemia could induce persistent early growth response gene-1 (Egr-1) activation in hepatocytes, which provides negative feedback inhibition of insulin sensitivity by inducing the expression of protein tyrosine phosphatase-1B (PTP1B). Deletion of Egr-1 in the liver remarkably decreases glucose production, thus improving systemic glucose tolerance and insulin sensitivity. Mechanistic analysis indicates that Egr-1 inhibits insulin receptor phosphorylation by directly activating PTP1B transcription in the liver. Our results reveal the molecular mechanism by which hyperinsulinemia accelerates insulin resistance in hepatocytes during the progression of T2DM.
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Affiliation(s)
- Jing Wu
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Weiwei Tao
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Dandan Bu
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Yue Zhao
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Tongyu Zhang
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Danyang Chong
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Bin Xue
- Core Laboratory, Sir Run Run Hospital, Nanjing Medical University, China
| | - Zheng Xing
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
| | - Chaojun Li
- Medical School of Nanjing University, China.,Model Animal Research Center, Nanjing University, China
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6
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Lu H, Bogdanovic E, Yu Z, Cho C, Liu L, Ho K, Guo J, Yeung LSN, Lehmann R, Hundal HS, Giacca A, Fantus IG. Combined Hyperglycemia- and Hyperinsulinemia-Induced Insulin Resistance in Adipocytes Is Associated With Dual Signaling Defects Mediated by PKC-ζ. Endocrinology 2018; 159:1658-1677. [PMID: 29370351 PMCID: PMC5939637 DOI: 10.1210/en.2017-00312] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 01/03/2018] [Indexed: 12/27/2022]
Abstract
A hyperglycemic and hyperinsulinemic environment characteristic of type 2 diabetes causes insulin resistance. In adipocytes, defects in both insulin sensitivity and maximum response of glucose transport have been demonstrated. To investigate the molecular mechanisms, freshly isolated rat adipocytes were incubated in control (5.6 mM glucose, no insulin) and high glucose (20 mM)/high insulin (100 nM) (HG/HI) for 18 hours to induce insulin resistance. Insulin-resistant adipocytes manifested decreased sensitivity of glucose uptake associated with defects in insulin receptor substrate (IRS)-1 Tyr phosphorylation, association of p85 subunit of phosphatidylinositol-3-kinase, Akt Ser473 and Thr308 phosphorylation, accompanied by impaired glucose transporter 4 translocation. In contrast, protein kinase C (PKC)-ζ activity was augmented by chronic HG/HI. Inhibition of PKC-ζ with a specific cell-permeable peptide reversed the signaling defects and insulin sensitivity of glucose uptake. Transfection of dominant-negative, kinase-inactive PKC-ζ blocked insulin resistance, whereas constitutively active PKC-ζ recapitulated the defects. The HG/HI incubation was associated with stimulation of IRS-1 Ser318 and Akt Thr34 phosphorylation, targets of PKC-ζ. Transfection of IRS-1 S318A and Akt T34A each partially corrected insulin signaling, whereas combined transfection of both completely normalized insulin signaling. In vivo hyperglycemia/hyperinsulinemia in rats for 48 hours similarly resulted in activation of PKC-ζ and increased phosphorylation of IRS-1 Ser318 and Akt Thr34. These data indicate that impairment of insulin signaling by chronic HG/HI is mediated by dual defects at IRS-1 and Akt mediated by PKC-ζ.
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Affiliation(s)
- Huogen Lu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Elena Bogdanovic
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Zhiwen Yu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Charles Cho
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lijiang Liu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Karen Ho
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - June Guo
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lucy S N Yeung
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Reiner Lehmann
- Department of Internal Medicine IV, Endocrinology, Metabolism, Pathobiochemistry and Clinical Chemistry, University Hospital Tuebingen, Tuebingen, Germany
| | - Harinder S Hundal
- Division of Molecular Physiology Unit, Faculty of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Adria Giacca
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - I George Fantus
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Correspondence: I. George Fantus, MD, Departments of Medicine and Physiology, Mount Sinai Hospital, Joseph and Wolfe Lebovic Building, 60 Murray Street, 5th Floor, Room 5028, Toronto, Ontario M5T 3L9, Canada. E-mail:
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7
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Norouzi S, Adulcikas J, Sohal SS, Myers S. Zinc stimulates glucose oxidation and glycemic control by modulating the insulin signaling pathway in human and mouse skeletal muscle cell lines. PLoS One 2018; 13:e0191727. [PMID: 29373583 PMCID: PMC5786307 DOI: 10.1371/journal.pone.0191727] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 01/10/2018] [Indexed: 01/01/2023] Open
Abstract
Zinc is a metal ion that is an essential cell signaling molecule. Highlighting this, zinc is an insulin mimetic, activating cellular pathways that regulate cellular homeostasis and physiological responses. Previous studies have linked dysfunctional zinc signaling with several disease states including cancer, obesity, cardiovascular disease and type 2 diabetes. The present study evaluated the insulin-like effects of zinc on cell signaling molecules including tyrosine, PRSA40, Akt, ERK1/2, SHP-2, GSK-3β and p38, and glucose oxidation in human and mouse skeletal muscle cells. Insulin and zinc independently led to the phosphorylation of these proteins over a 60-minute time course in both mouse and human skeletal muscle cells. Similarly, utilizing a protein array we identified that zinc could active the phosphorylation of p38, ERK1/2 and GSK-3B in human and ERK1/2 and GSK-3B in mouse skeletal muscle cells. Glucose oxidation assays were performed on skeletal muscle cells treated with insulin, zinc, or a combination of both and resulted in a significant induction of glucose consumption in mouse (p<0.01) and human (p<0.05) skeletal muscle cells when treated with zinc alone. Insulin, as expected, increased glucose oxidation in mouse (p<0.001) and human (0.001) skeletal muscle cells, however the combination of zinc and insulin did not augment glucose consumption in these cells. Zinc acts as an insulin mimetic, activating key molecules implicated in cell signaling to maintain glucose homeostasis in mouse and human skeletal muscle cells. Zinc is an important metal ion implicated in several biological processes. The role of zinc as an insulin memetic in activating key signaling molecules involved in glucose homeostasis could provide opportunities to utilize this ion therapeutically in treating disorders associated with dysfunctional zinc signaling.
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Affiliation(s)
- Shaghayegh Norouzi
- College of Health and Medicine, School of Health Sciences, University of Tasmania, Newnham Campus, Launceston, Tasmania, Australia
| | - John Adulcikas
- College of Health and Medicine, School of Health Sciences, University of Tasmania, Newnham Campus, Launceston, Tasmania, Australia
| | - Sukhwinder Singh Sohal
- College of Health and Medicine, School of Health Sciences, University of Tasmania, Newnham Campus, Launceston, Tasmania, Australia
| | - Stephen Myers
- College of Health and Medicine, School of Health Sciences, University of Tasmania, Newnham Campus, Launceston, Tasmania, Australia
- * E-mail:
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8
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Frigolet ME, Thomas G, Beard K, Lu H, Liu L, Fantus IG. The bradykinin-cGMP-PKG pathway augments insulin sensitivity via upregulation of MAPK phosphatase-5 and inhibition of JNK. Am J Physiol Endocrinol Metab 2017; 313:E321-E334. [PMID: 28679626 DOI: 10.1152/ajpendo.00298.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 01/13/2023]
Abstract
Bradykinin (BK) promotes insulin sensitivity and glucose uptake in adipocytes and other cell types. We demonstrated that in rat adipocytes BK enhances insulin-stimulated glucose transport via endothelial nitric oxide synthase, nitric oxide (NO) generation, and decreased activity of the mitogen-activated protein kinase (MAPK) JNK (c-Jun NH2-terminal kinase). In endothelial cells, NO increases soluble guanylate cyclase (sGC) activity, which, in turn, activates protein kinase G (PKG) by increasing cGMP levels. In this study, we investigated whether BK acts via the sGC-cGMP-PKG pathway to inhibit the negative effects of JNK on insulin signaling and glucose uptake in rat adipocytes. BK augmented cGMP concentrations. The BK-induced enhancement of insulin-stimulated glucose uptake was mimicked by the sGC activator YC-1 and a cell-permeable cGMP analog, CPT-cGMP, and inhibited by the sGC inhibitor ODQ and the PKG inhibitor KT 5823. Transfection of dominant-negative PKG reduced the BK augmentation of insulin-induced Akt phosphorylation. The activation of JNK and ERK1/2 by insulin was attenuated by BK, which was mediated by the sGC-cGMP-PKG pathway. Whereas insulin-stimulated phosphorylation of upstream activators of JNK and ERK, i.e., MKK4 and MEK1/2, was unaffected, BK augmented insulin-mediated induction of MKP-5 mRNA and protein levels. Furthermore, zaprinast, a phosphodiesterase inhibitor, enhanced cGMP and MKP-5 and prolonged the action of BK. These data indicate that BK enhances insulin action by inhibition of negative feedback by JNK and ERK via upregulation of MKP-5, mediated by the sGC-cGMP-PKG signaling pathway.
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Affiliation(s)
- María E Frigolet
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, Toronto, Ontario, Canada; and
| | - Garry Thomas
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, Toronto, Ontario, Canada; and
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Kristin Beard
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, Toronto, Ontario, Canada; and
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Huogen Lu
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Lijiang Liu
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - I George Fantus
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada;
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, Toronto, Ontario, Canada; and
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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9
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Katsoulieris EN, Drossopoulou GI, Kotsopoulou ES, Vlahakos DV, Lianos EA, Tsilibary EC. High Glucose Impairs Insulin Signaling in the Glomerulus: An In Vitro and Ex Vivo Approach. PLoS One 2016; 11:e0158873. [PMID: 27434075 PMCID: PMC4951020 DOI: 10.1371/journal.pone.0158873] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/23/2016] [Indexed: 01/14/2023] Open
Abstract
Objective Chronic hyperglycaemia, as seen in type II diabetes, results in both morphological and functional impairments of podocytes in the kidney. We investigated the effects of high glucose (HG) on the insulin signaling pathway, focusing on cell survival and apoptotic markers, in immortalized human glomerular cells (HGEC; podocytes) and isolated glomeruli from healthy rats. Methods and Findings HGEC and isolated glomeruli were cultured for various time intervals under HG concentrations in the presence or absence of insulin. Our findings indicated that exposure of HGEC to HG led to downregulation of all insulin signaling markers tested (IR, p-IR, IRS-1, p-Akt, p-Fox01,03), as well as to increased sensitivity to apoptosis (as seen by increased PARP cleavage, Casp3 activation and DNA fragmentation). Short insulin pulse caused upregulation of insulin signaling markers (IR, p-IR, p-Akt, p-Fox01,03) in a greater extent in normoglycaemic cells compared to hyperglycaemic cells and for the case of p-Akt, in a PI3K-dependent manner. IRS-1 phosphorylation of HG-treated podocytes was negatively regulated, favoring serine versus tyrosine residues. Prolonged insulin treatment caused a significant decrease of IR levels, while alterations in glucose concentrations for various time intervals demonstrated changes of IR, p-IR and p-Akt levels, suggesting that the IR signaling pathway is regulated by glucose levels. Finally, HG exerted similar effects in isolated glomeruli. Conclusions These results suggest that HG compromises the insulin signaling pathway in the glomerulus, promoting a proapoptotic environment, with a possible critical step for this malfunction lying at the level of IRS-1 phosphorylation; thus we herein demonstrate glomerular insulin signaling as another target for investigation for the prevention and/ or treatment of diabetic nephropathy.
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Affiliation(s)
- Elias N. Katsoulieris
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
| | - Garyfalia I. Drossopoulou
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
- * E-mail: (GID); (ECT)
| | - Eleni S. Kotsopoulou
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
| | - Dimitrios V. Vlahakos
- 2nd Department of Propaedeutic Medicine, Attikon University Hospital, Athens, Greece
| | - Elias A. Lianos
- Department of Pathology, National and Kapodistrian University of Athens, Medical School, Athens, Greece
| | - Effie C. Tsilibary
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
- * E-mail: (GID); (ECT)
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10
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Palacios-Ortega S, Varela-Guruceaga M, Martínez JA, de Miguel C, Milagro FI. Effects of high glucose on caveolin-1 and insulin signaling in 3T3-L1 adipocytes. Adipocyte 2016; 5:65-80. [PMID: 27144098 DOI: 10.1080/21623945.2015.1122856] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/29/2015] [Accepted: 11/12/2015] [Indexed: 12/17/2022] Open
Abstract
Adipocytes exposed to high glucose concentrations exhibit impaired metabolic function, including an increase of oxidative and proinflammatory factors that might favor the development of insulin resistance. Caveolin-1 (Cav-1) is a key mediator of the insulin transduction pathway whose expression is significantly enhanced during adipocyte differentiation. In this work, we studied the effects of high glucose concentration on the regulation of Cav-1 expression and activation and its relation to the insulin signaling pathway during the adipogenic process and in long-term differentiated adipocytes. Both, long-term high glucose exposure during adipogenesis and short-term glucose incubation of mature adipocytes, promoted triglyceride accumulation in 3T3-L1 cells. The short-term exposure of mature adipocytes to high glucose significantly reduced the sensitivity to insulin of Cav-1, insulin receptor (IR) and potein kinase B (AKT-2) phosphorylation, as well as insulin-induced deoxyglucose uptake. Adipocytes differentiated in the presence of high glucose lost Cav-1 and IR response to insulin-stimulated phosphorylation, but maintained the insulin sensitivity of AKT-2 phosphorylation and deoxyglucose uptake. Although long-term high glucose exposure increased DNA methylation in Cav-1 promoter, Cav-1 expression was not affected. Moreover, these cells showed an increase of Cav-1, IR and AKT-2 protein content, pointing to an adaptive response induced by the long-term high glucose exposure.
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11
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Varinli H, Osmond-McLeod MJ, Molloy PL, Vallotton P. LipiD-QuanT: a novel method to quantify lipid accumulation in live cells. J Lipid Res 2015; 56:2206-16. [PMID: 26330056 DOI: 10.1194/jlr.d059758] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Indexed: 12/17/2022] Open
Abstract
Lipid droplets (LDs) are the main storage organelles for triglycerides. Elucidation of lipid accumulation mechanisms and metabolism are essential to understand obesity and associated diseases. Adipogenesis has been well studied in murine 3T3-L1 and human Simpson-Golabi-Behmel syndrome (SGBS) preadipocyte cell lines. However, most techniques for measuring LD accumulation are either not quantitative or can be destructive to samples. Here, we describe a novel, label-free LD quantification technique (LipiD-QuanT) to monitor lipid dynamics based on automated image analysis of phase contrast microscopy images acquired during in vitro human adipogenesis. We have applied LipiD-QuanT to measure LD accumulation during differentiation of SGBS cells. We demonstrate that LipiD-QuanT is a robust, nondestructive, time- and cost-effective method compared with other triglyceride accumulation assays based on enzymatic digest or lipophilic staining. Further, we applied LipiD-QuanT to measure the effect of four potential pro- or antiobesogenic substances: DHA, rosiglitazone, elevated levels of D-glucose, and zinc oxide nanoparticles. Our results revealed that 2 µmol/l rosiglitazone treatment during adipogenesis reduced lipid production and caused a negative shift in LD diameter size distribution, but the other treatments showed no effect under the conditions used here.
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Affiliation(s)
- Hilal Varinli
- CSIRO Food and Nutrition Flagship, North Ryde, New South Wales, Australia Department of Biological Sciences, Macquarie University, North Ryde, New South Wales, Australia Genomics and Epigenetics Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Megan J Osmond-McLeod
- CSIRO Food and Nutrition Flagship, North Ryde, New South Wales, Australia CSIRO Advanced Materials TCP (Nanosafety), North Ryde, New South Wales, Australia
| | - Peter L Molloy
- CSIRO Food and Nutrition Flagship, North Ryde, New South Wales, Australia
| | - Pascal Vallotton
- CSIRO Digital Productivity Flagship, North Ryde, New South Wales, Australia
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Liu L, Ke W, Wan X, Zhang P, Cao X, Deng W, Li Y. Insulin requirement profiles of short-term intensive insulin therapy in patients with newly diagnosed type 2 diabetes and its association with long-term glycemic remission. Diabetes Res Clin Pract 2015; 108:250-7. [PMID: 25765670 DOI: 10.1016/j.diabres.2015.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/23/2014] [Accepted: 02/13/2015] [Indexed: 01/19/2023]
Abstract
AIMS To investigate the insulin requirement profiles during short-term intensive continuous subcutaneous insulin infusion (CSII) in patients with newly diagnosed type 2 diabetes and its relationship with long-term glycemic remission. METHODS CSII was applied in 104 patients with newly diagnosed type 2 diabetes. Daily insulin doses were titrated and recorded to achieve and maintain euglycemia for 2 weeks. Measurements of blood glucose, lipid profiles as well as intravenous glucose tolerance tests were performed before and after the therapy. Afterwards, patients were followed up for 1 year. RESULTS Total daily insulin dose (TDD) was 56.6±16.1IU at the first day when euglycemia was achieved (TDD-1). Thereafter, TDD progressively decreased at a rate of 1.4±1.0IU/day to 36.2±16.5IU at the end of the therapy. TDD-1 could be estimated with body weight, FPG, triglyceride and waist circumference in a multiple linear regression model. Decrement of TDD after euglycemia was achieved (ΔTDD) was associated with reduction of HOMA-IR (r=0.27, P=0.008) but not with improvement in β cell function. Patients in the lower tertile of ΔTDD had a significantly higher risk of hyperglycemia relapse than those in the upper tertile within 1 year (HR 3.4, 95%CI [1.4, 8.4], P=0.008). CONCLUSIONS There is a steady decline of TDD after euglycemia is achieved in patients with newly diagnosed type 2 diabetes treated with CSII, and ΔTDD is associated with a better long-term glycemic outcome.
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Affiliation(s)
- Liehua Liu
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China
| | - Weijian Ke
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China
| | - Xuesi Wan
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China
| | - Pengyuan Zhang
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China
| | - Xiaopei Cao
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China
| | - Wanping Deng
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China
| | - Yanbing Li
- Department of Endocrinology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58, Zhongshan er Road, Guangzhou 510080, China.
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13
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Myers SA. Zinc transporters and zinc signaling: new insights into their role in type 2 diabetes. Int J Endocrinol 2015; 2015:167503. [PMID: 25983752 PMCID: PMC4423030 DOI: 10.1155/2015/167503] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 04/07/2015] [Accepted: 04/12/2015] [Indexed: 12/13/2022] Open
Abstract
Zinc is an essential trace element that plays a vital role in many biological processes including growth and development, immunity, and metabolism. Recent studies have highlighted zinc's dynamic role as a "cellular second messenger" in the control of insulin signaling and glucose homeostasis. Accordingly, mechanisms that contribute to dysfunctional zinc signaling are suggested to be associated with metabolic disease states including cancer, cardiovascular disease, Alzheimer's disease, and diabetes. The actions of the proteins that control the uptake, storage, and distribution of zinc, the zinc transporters, are under intense investigation due to their emerging role in type 2 diabetes. The synthesis, secretion, and action of insulin are dependent on zinc and the transporters that make this ion available to cellular processes. This suggests that zinc plays a previously unidentified role where changes in zinc status over time may affect insulin activity. This previously unexplored concept would raise a whole new area of research into the pathophysiology of insulin resistance and introduce a new class of drug target with utility for diabetes pharmacotherapy.
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Affiliation(s)
- Stephen A. Myers
- University of Tasmania (UTAS), School of Health Sciences, Newnham Campus, Launceston, TAS 7250, Australia
- *Stephen A. Myers:
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Oxidative stress and metabolic pathologies: from an adipocentric point of view. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:908539. [PMID: 25143800 PMCID: PMC4131099 DOI: 10.1155/2014/908539] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/20/2014] [Accepted: 06/26/2014] [Indexed: 02/07/2023]
Abstract
Oxidative stress plays a pathological role in the development of various diseases including diabetes, atherosclerosis, or cancer. Systemic oxidative stress results from an imbalance between oxidants derivatives production and antioxidants defenses. Reactive oxygen species (ROS) are generally considered to be detrimental for health. However, evidences have been provided that they can act as second messengers in adaptative responses to stress. Obesity represents a major risk factor for deleterious associated pathologies such as type 2 diabetes, liver, and coronary heart diseases. Many evidences regarding obesity-induced oxidative stress accumulated over the past few years based on established correlations of biomarkers or end-products of free-radical-mediated oxidative stress with body mass index. The hypothesis that oxidative stress plays a significant role in the development of metabolic disorders, especially insulin-resistance state, is supported by several studies where treatments reducing ROS production reverse metabolic alterations, notably through improvement of insulin sensitivity, hyperlipidemia, or hepatic steatosis. In this review, we will develop the mechanistic links between oxidative stress generated by adipose tissue in the context of obesity and its impact on metabolic complications development. We will also attempt to discuss potential therapeutic approaches targeting obesity-associated oxidative stress in order to prevent associated-metabolic complications.
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15
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Myers SA, Nield A, Myers M. Zinc transporters, mechanisms of action and therapeutic utility: implications for type 2 diabetes mellitus. J Nutr Metab 2012; 2012:173712. [PMID: 23304467 PMCID: PMC3530793 DOI: 10.1155/2012/173712] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/07/2012] [Accepted: 11/07/2012] [Indexed: 12/29/2022] Open
Abstract
Zinc is an essential trace element that plays a vital role in maintaining many biological processes and cellular homeostasis. Dysfunctional zinc signaling is associated with a number of chronic disease states including cancer, cardiovascular disease, Alzheimer's disease, and diabetes. Cellular homeostasis requires mechanisms that tightly control the uptake, storage, and distribution of zinc. This is achieved through the coordinated actions of zinc transporters and metallothioneins. Evidence on the role of these proteins in type 2 diabetes mellitus (T2DM) is now emerging. Zinc plays a key role in the synthesis, secretion and action of insulin in both physiological and pathophysiological states. Moreover, recent studies highlight zinc's dynamic role as a "cellular second messenger" in the control of insulin signaling and glucose homeostasis. This suggests that zinc plays an unidentified role as a novel second messenger that augments insulin activity. This previously unexplored concept would raise a whole new area of research into the pathophysiology of insulin resistance and introduce a new class of drug target with utility for diabetes pharmacotherapy.
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Affiliation(s)
- Stephen A. Myers
- School of Health Sciences, University of Ballarat, University Drive, Mount Helen, VIC 3350, Australia
- Collaborative Research Network, University of Ballarat, Mount Helen, VIC 3350, Australia
| | - Alex Nield
- School of Health Sciences, University of Ballarat, University Drive, Mount Helen, VIC 3350, Australia
| | - Mark Myers
- School of Health Sciences, University of Ballarat, University Drive, Mount Helen, VIC 3350, Australia
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16
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Skrzypski M, T Le T, Kaczmarek P, Pruszynska-Oszmalek E, Pietrzak P, Szczepankiewicz D, Kolodziejski PA, Sassek M, Arafat A, Wiedenmann B, Nowak KW, Strowski MZ. Orexin A stimulates glucose uptake, lipid accumulation and adiponectin secretion from 3T3-L1 adipocytes and isolated primary rat adipocytes. Diabetologia 2011; 54:1841-52. [PMID: 21505958 DOI: 10.1007/s00125-011-2152-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 03/17/2011] [Indexed: 10/18/2022]
Abstract
AIMS/HYPOTHESIS Orexin A (OXA) modulates body weight, food intake and energy expenditure. In vitro, OXA increases PPARγ (also known as PPARG) expression and inhibits lipolysis, suggesting direct regulation of lipid metabolism. Here, we characterise the metabolic effects and mechanisms of OXA action in adipocytes. METHODS Isolated rat adipocytes and differentiated murine 3T3-L1 adipocytes were exposed to OXA in the presence or absence of phosphoinositide 3-kinase (PI3K) inhibitors. Pparγ expression was silenced using small interfering RNA. Glucose uptake, GLUT4 translocation, phosphatidylinositol (3,4,5)-trisphosphate production, lipogenesis, lipolysis, and adiponectin secretion were measured. Adiponectin plasma levels were determined in rats treated with OXA for 4 weeks. RESULTS OXA PI3K-dependently stimulated active glucose uptake by translocating the glucose transporter GLUT4 from cytoplasm into the plasma membrane. OXA increased cellular triacylglycerol content via PI3K. Cellular triacylglycerol accumulation resulted from increased lipogenesis as well as from a decrease of lipolysis. Adiponectin levels in chow- and high-fat diet-fed rats treated chronically with OXA were increased. OXA stimulated adiponectin expression and secretion in adipocytes. Both pharmacological blockade of peroxisome proliferator-activated receptor γ (PPARγ) activity or silencing Pparγ expression prevented OXA from stimulating triacylglycerol accumulation and adiponectin production. CONCLUSIONS/INTERPRETATION Our study demonstrates that OXA stimulates glucose uptake in adipocytes and that the evolved energy is stored as lipids. OXA increases lipogenesis, inhibits lipolysis and stimulates the secretion of adiponectin. These effects are conferred via PI3K and PPARγ2. Overall, OXA's effects on lipids and adiponectin secretion resemble that of insulin sensitisers, suggesting a potential relevance of this peptide in metabolic disorders.
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Affiliation(s)
- M Skrzypski
- Department of Hepatology and Gastroenterology and Interdisciplinary Centre of Metabolism: Endocrinology, Diabetes and Metabolism, Charité-University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
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17
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Hsu MF, Meng TC. Enhancement of insulin responsiveness by nitric oxide-mediated inactivation of protein-tyrosine phosphatases. J Biol Chem 2010; 285:7919-28. [PMID: 20064934 DOI: 10.1074/jbc.m109.057513] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NO synthesis is a prerequisite for proper insulin sensitivity in insulin-targeted tissues; however, the molecular basis for this process remains unclear. Using a gain-of-function model of endothelial nitric-oxide synthase (eNOS)-transfected COS-7 cells, we have shown a critical role of NO in insulin responsiveness, as evidenced by an NO-dependent increase of tyrosine phosphorylation levels of the insulin receptor and its downstream effectors insulin receptor substrate-1 and PKB/AKT. We hypothesized that NO-induced inactivation of endogenous protein-tyrosine phosphatases (PTPs) would enhance insulin receptor-mediated signaling. To test this hypothesis, we devised a new method of the PTP labeling using a cysteine sulfhydryl-reacted probe. Under the acidic conditions employed in this study, the probe recognized the reduced and active forms but not the S-nitrosylated and inactive forms of endogenous PTPs. Our data suggest that phosphatases SHP-1, SHP-2, and PTP1B, but not TC-PTP, are likely S-nitrosylated at the active site cysteine residue concomitantly with a burst of NO production in signaling response to insulin stimulation. These results were further confirmed by phosphatase activity assays. We investigated further the role of NO as a regulator of insulin signaling by RNA interference that ablates endogenous eNOS expression in endothelial MS-1 cells. We have shown that eNOS-dependent NO production is essential for the activation of insulin signaling. Our findings demonstrate that NO mediates enhancement of insulin responsiveness via the inhibition of insulin receptor phosphatases.
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Affiliation(s)
- Ming-Fo Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
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18
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Lim GE, Huang GJ, Flora N, LeRoith D, Rhodes CJ, Brubaker PL. Insulin regulates glucagon-like peptide-1 secretion from the enteroendocrine L cell. Endocrinology 2009; 150:580-91. [PMID: 18818290 PMCID: PMC5393261 DOI: 10.1210/en.2008-0726] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Insulin resistance and type 2 diabetes mellitus are associated with impaired postprandial secretion of glucagon-like peptide-1 (GLP-1), a potent insulinotropic hormone. The direct effects of insulin and insulin resistance on the L cell are unknown. We therefore hypothesized that the L cell is responsive to insulin and that insulin resistance impairs GLP-1 secretion. The effects of insulin and insulin resistance were examined in well-characterized L cell models: murine GLUTag, human NCI-H716, and fetal rat intestinal cells. MKR mice, a model of chronic hyperinsulinemia, were used to assess the function of the L cell in vivo. In all cells, insulin activated the phosphatidylinositol 3 kinase-Akt and MAPK kinase (MEK)-ERK1/2 pathways and stimulated GLP-1 secretion by up to 275 +/- 58%. Insulin resistance was induced by 24 h pretreatment with 10(-7) m insulin, causing a marked reduction in activation of Akt and ERK1/2. Furthermore, both insulin-induced GLP-1 release and secretion in response to glucose-dependent insulinotropic peptide and phorbol-12-myristate-13-acetate were significantly attenuated. Whereas inhibition of phosphatidylinositol 3 kinase with LY294002 potentiated insulin-induced GLP-1 release, secretion was abrogated by inhibiting the MEK-ERK1/2 pathway with PD98059 or by overexpression of a kinase-dead MEK1-ERK2 fusion protein. Compared with controls, MKR mice were insulin resistant and displayed significantly higher fasting plasma insulin levels. Furthermore, they had significantly higher basal GLP-1 levels but displayed impaired GLP-1 secretion after an oral glucose challenge. These findings indicate that the intestinal L cell is responsive to insulin and that insulin resistance in vitro and in vivo is associated with impaired GLP-1 secretion.
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Affiliation(s)
- Gareth E Lim
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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19
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Ordóñez P, Moreno M, Alonso A, Fernández R, Díaz F, González C. Insulin sensitivity in streptozotocin-induced diabetic rats treated with different doses of 17beta-oestradiol or progesterone. Exp Physiol 2006; 92:241-9. [PMID: 17068109 DOI: 10.1113/expphysiol.2006.035006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It has been reported that in streptozotocin (STZ)-induced diabetes, hyperglycaemia leads to progressive insulin resistance of the peripheral tissues. In this study, we tried to elucidate the effects of hyperglycaemia on insulin sensitivity and insulin signalling in ovariectomized (STZ)-induced diabetic rats. In addition, we attempted to demonstrate the role of 17beta-oestradiol and progesterone on insulin sensitivity, focusing on their effects on key proteins of skeletal muscle, insulin receptor (IR) and glucose transporter-4 (Glut-4). Our results show that hyperglycaemia could modulate insulin signalling, at the IR and Glut-4 level, in different ways depending on exposure time. 17beta-Oestradiol and progesterone have different effects on insulin signalling. 17beta-Oestradiol treatment improves insulin sensitivity, but its action is dependent on the exposure time and its plasma level. During the early period of treatment (days 6-11), this hormone counteracts the effects of hyperglycaemia downstream of the IR, whereas during the later period of treatment (days 11-16), it may counteract the effects of hyperglycaemia by modulating IR relative tyrosine phosphorylation. By contrast, progesterone only improves insulin sensitivity during the early period of treatment (days 6-11), and this effect is not associated with changes in IR and Glut-4 content. Both hormones have a protective role in skeletal muscle against the effects of glucose toxicity, but their effects begin at different stages of treatment. These new findings improve our understanding of insulin resistance in type 1 diabetes mellitus and of the risk/benefit ratio when 17beta-oestradiol and progesterone are used in oral contraceptives or hormone replacement therapy taken by menopausal women with controlled type 1 diabetes mellitus.
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Affiliation(s)
- Patricia Ordóñez
- Department of Functional Biology, Physiology Area, University of Oviedo, C/ Julián Clavería s/n 3306, Oviedo, Spain
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20
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Beard KM, Lu H, Ho K, Fantus IG. Bradykinin augments insulin-stimulated glucose transport in rat adipocytes via endothelial nitric oxide synthase-mediated inhibition of Jun NH2-terminal kinase. Diabetes 2006; 55:2678-87. [PMID: 17003331 DOI: 10.2337/db05-1538] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
An increase in bradykinin has been suggested to contribute to the enhanced insulin sensitivity observed in the presence of ACE inhibitors. To investigate a potential direct, nonvascular effect on an insulin target tissue, the effect of bradykinin on glucose uptake and insulin signaling was studied in primary rat adipocytes. Whereas basal glucose uptake was not altered, bradykinin augmented insulin-stimulated glucose uptake twofold, which was blocked by HOE-140, a bradykinin B2 receptor antagonist. The bradykinin effect on glucose uptake was nitric oxide (NO) dependent, mimicked by NO donors and absent in adipocytes from endothelial NO synthase-/- mice. Investigation of insulin signaling revealed that bradykinin enhanced insulin receptor substrate-1 (IRS-1) Tyr phosphorylation, Akt/protein kinase B phosphorylation, and GLUT4 translocation. In contrast, insulin-stimulated extracellular signal-regulated kinase1/2 and Jun NH2-terminal kinase (JNK) activation were decreased in the presence of bradykinin, accompanied by decreased IRS-1 Ser307 phosphorylation. Furthermore, bradykinin did not enhance insulin action in the presence of the JNK inhibitor, SP-600125, or in adipocytes from JNK1-/- mice. These data indicate that bradykinin enhances insulin sensitivity in adipocytes via an NO-dependent pathway that acts by modulating the feedback inhibition of insulin signaling at the level of IRS-1.
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Affiliation(s)
- Kristin M Beard
- Department of Medicine and Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada M5G 1X6
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21
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Wu X, Zhu L, Zilbering A, Mahadev K, Motoshima H, Yao J, Goldstein BJ. Hyperglycemia potentiates H(2)O(2) production in adipocytes and enhances insulin signal transduction: potential role for oxidative inhibition of thiol-sensitive protein-tyrosine phosphatases. Antioxid Redox Signal 2005; 7:526-37. [PMID: 15889998 PMCID: PMC1435729 DOI: 10.1089/ars.2005.7.526] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Insulin signal transduction in adipocytes is accompanied by a burst of cellular hydrogen peroxide (H(2)O(2)) that facilitates insulin signaling by inhibiting thiol-dependent protein-tyrosine phosphatases (PTPs) that are negative regulators of insulin action. As hyperglycemia is associated with increased cellular reactive oxygen species, we postulated that high glucose conditions might potentiate the H(2)O(2) generated by insulin and modulate insulin-stimulated protein phosphorylation. Basal H(2)O(2) generation was increased threefold in differentiated 3T3-L1 adipocytes by growth in 25 mM glucose versus 5 mM glucose. High glucose increased the sensitivity of the insulin-stimulated H(2)O(2) signal to lower concentrations of insulin. Basal endogenous total PTP activity and the activity of PTP1B, a PTP implicated in the negative regulation of insulin signaling, were reduced in high glucose conditions, and their further reduction by insulin stimulation was more enhanced in high versus low glucose medium. Phosphorylation of the insulin receptor, IRS-1, and Akt in response to insulin was also significantly enhanced in high glucose conditions, especially at submaximal insulin concentrations. In primary rat adipocytes, high glucose increased insulin-stimulated H(2)O(2) production and potentiated the oxidative inhibition of total PTP and PTP1B activity; however, insulin signaling was not enhanced in the primary cells in high glucose apparently due to cross-regulation of insulin-stimulated protein phosphorylation by activation of protein kinase C (PKC). These studies indicate that high glucose can enhance insulin stimulated H(2)O(2) generation and augment oxidative PTP inhibition in cultured and primary adipocytes, but the overall balance of insulin signal transduction is determined by additional signal effects in high glucose, including the activation of PKC.
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Affiliation(s)
- Xiangdong Wu
- Dorrance H. Hamilton Research Laboratories, Division of Endocrinology, Diabetes and Metabolic Diseases, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107, USA
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22
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Lin Y, Berg AH, Iyengar P, Lam TKT, Giacca A, Combs TP, Rajala MW, Du X, Rollman B, Li W, Hawkins M, Barzilai N, Rhodes CJ, Fantus IG, Brownlee M, Scherer PE. The hyperglycemia-induced inflammatory response in adipocytes: the role of reactive oxygen species. J Biol Chem 2004; 280:4617-26. [PMID: 15536073 DOI: 10.1074/jbc.m411863200] [Citation(s) in RCA: 369] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Hyperglycemia is a major independent risk factor for diabetic macrovascular disease. The consequences of exposure of endothelial cells to hyperglycemia are well established. However, little is known about how adipocytes respond to both acute as well as chronic exposure to physiological levels of hyperglycemia. Here, we analyze adipocytes exposed to hyperglycemia both in vitro as well as in vivo. Comparing cells differentiated at 4 mm to cells differentiated at 25 mm glucose (the standard differentiation protocol) reveals severe insulin resistance in cells exposed to 25 mm glucose. A global assessment of transcriptional changes shows an up-regulation of a number of mitochondrial proteins. Exposure to hyperglycemia is associated with a significant induction of reactive oxygen species (ROS), both in vitro as well as in vivo in adipocytes isolated from streptozotocin-treated hyperglycemic mice. Furthermore, hyperglycemia for a few hours in a clamped setting will trigger the induction of a pro-inflammatory response in adipose tissue from rats that can effectively be reduced by co-infusion of N-acetylcysteine (NAC). ROS levels in 3T3-L1 adipocytes can be reduced significantly with pharmacological agents that lower the mitochondrial membrane potential, or by overexpression of uncoupling protein 1 or superoxide dismutase. In parallel with ROS, interleukin-6 secretion from adipocytes is significantly reduced. On the other hand, treatments that lead to a hyperpolarization of the mitochondrial membrane, such as overexpression of the mitochondrial dicarboxylate carrier result in increased ROS formation and decreased insulin sensitivity, even under normoglycemic conditions. Combined, these results highlight the importance ROS production in adipocytes and the associated insulin resistance and inflammatory response.
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Affiliation(s)
- Ying Lin
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Cruz M, Velasco E, Kumate J. Degradation of pro-insulin-receptor proteins by proteasomes. Arch Med Res 2004; 35:18-23. [PMID: 15036795 DOI: 10.1016/j.arcmed.2003.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2002] [Accepted: 08/29/2003] [Indexed: 11/21/2022]
Abstract
BACKGROUND Type-2 diabetes is characterized by hyperinsulinemia, peripheral insulin resistance, and diminished tyrosine phosphorylation activity. It has been recently shown that proteasomes are implicated in the degradation of the insulin receptor substrate-1 (IRS-1) but not in that of the insulin receptor (IR). However, it is unknown whether proteasomes are involved in pro-IR degradation. METHODS We used CHO-IR and the 3T3-L1 cells treated with insulin at different concentrations and compared the proteasome activity of IRS-1, IR, and pro-IR degradation either in presence or in absence of lactacystin. RESULTS A total of 100 nM of insulin allowed degradation of IRS-1 after 6 h of incubation. At 1,000 nM of insulin, pro-IR degradation began at 1 h of incubation, similar to IRS-1 degradation. Surprisingly, at a higher concentration (10 microM) of insulin, a drastic decrease of proteins was observed from the first minute of incubation. This activity was blocked by lactacystin, a specific proteasome inhibitor. CONCLUSIONS According to these results, we propose that pro-IR is degraded by proteasomes.
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Affiliation(s)
- Miguel Cruz
- Unidad de Investigación Medica en Bioquímica, Hospital de Especialidades, Centro Medico Nacional Siglo XXI (CMNSXXI), Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico.
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Clampit JE, Meuth JL, Smith HT, Reilly RM, Jirousek MR, Trevillyan JM, Rondinone CM. Reduction of protein-tyrosine phosphatase-1B increases insulin signaling in FAO hepatoma cells. Biochem Biophys Res Commun 2003; 300:261-7. [PMID: 12504077 DOI: 10.1016/s0006-291x(02)02839-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Protein-tyrosine phosphatase-1B (PTP1B) has been implicated as a negative regulator of insulin signaling. PTP1B dephosphorylates the insulin receptor and insulin receptor substrates (IRS-1/2), inhibiting the insulin-signaling pathway. PTP1B has been reported to be elevated in diabetes and insulin-resistant states. Conversely, PTP1B null mice have increased insulin sensitivity. To further investigate the effect of PTP1B reduction on insulin signaling, FAO rat hepatoma cells were transfected, by electroporation, with a specific PTP1B antisense oligonucleotide (ASO), or a control oligonucleotide. The PTP1B ASO caused a 50-70% reduction in PTP1B protein expression as measured by Western blot analysis. Upon insulin stimulation, an increase in the phosphorylation of the insulin receptor and insulin receptor substrates was observed, without any change in protein expression levels. Reduction of PTP1B expression in FAO cells also caused an increase in insulin-stimulated phosphorylation of PKB and GSK3, without any change in protein expression. These results demonstrate that reduction of PTP1B can modulate key insulin signaling events downstream of the insulin receptor.
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Affiliation(s)
- Jill E Clampit
- Insulin Signaling, Metabolic Diseases Research, Global Pharmaceutical Research Division, Abbott Laboratories, Department 47R, Building AP10, 100 Abbott Park Road, Abbott Park, IL 60064-6009, USA
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25
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González C, Alonso A, Grueso NA, Díaz F, Esteban MM, Fernández S, Patterson AM. Role of 17beta-estradiol administration on insulin sensitivity in the rat: implications for the insulin receptor. Steroids 2002; 67:993-1005. [PMID: 12441184 DOI: 10.1016/s0039-128x(02)00073-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of 17beta-estradiol in the early steps of insulin action is only partially known, although its effect on glucose homeostasis has been reported. In this paper, we attempt to prove the influence of 17beta-estradiol on the insulin receptor of ovariectomized rats treated with different hormonal doses. Our results show that high doses of estradiol impair insulin sensitivity while low doses improve it. We think that these results are the consequence of changes at a molecular level, because high doses of estradiol produced lower expression of the insulin receptor gene, lower content of this receptor in target tissues, and lower phosphorylation of insulin receptor in these tissues. However, low doses of estradiol seem to produce just the opposite. The possible existence of consensus response elements in the insulin receptor gene promoter to estradiol could be controlling the expression of this gene, this control being dose and timing dependent. Moreover, we cannot discard a possible effect of estradiol on the activity of protein tyrosine phosphatases, and therefore, on the activity of the insulin receptor. These new findings improve knowledge about the possible risk for insulin resistance in women taking oral contraceptives or receiving hormonal replacement therapy around the menopause, but could also open the door towards the possible utilization of 17beta-estradiol in some diabetes cases.
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Affiliation(s)
- Celestino González
- Departamento de Biología Funcional (Fisiología), Facultad de Medicina, Universidad de Oviedo, C/Julián Clavería s/n, 33006, Oviedo, Spain.
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Lu B, Ennis D, Lai R, Bogdanovic E, Nikolov R, Salamon L, Fantus C, Le-Tien H, Fantus IG. Enhanced sensitivity of insulin-resistant adipocytes to vanadate is associated with oxidative stress and decreased reduction of vanadate (+5) to vanadyl (+4). J Biol Chem 2001; 276:35589-98. [PMID: 11463798 DOI: 10.1074/jbc.m106783200] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Vanadate (sodium orthovanadate), an inhibitor of phosphotyrosine phosphatases (PTPs), mimics many of the metabolic actions of insulin in vitro and in vivo. The potential of vanadate to stimulate glucose transport independent of the early steps in insulin signaling prompted us to test its effectiveness in an in vitro model of insulin resistance. In primary rat adipocytes cultured for 18 h in the presence of high glucose (15 mm) and insulin (10(-7) m), sensitivity to insulin-stimulated glucose transport was decreased. In contrast, there was a paradoxical enhanced sensitivity to vanadate of the insulin-resistant cells (EC(50) for control, 325 +/- 7.5 microm; EC(50) for insulin-resistant, 171 +/- 32 microm; p < 0.002). Enhanced sensitivity was also present for vanadate stimulation of insulin receptor kinase activity and autophosphorylation and Akt/protein kinase B Ser-473 phosphorylation consistent with more effective PTP inhibition in the resistant cells. Investigation of this phenomenon revealed that 1) depletion of GSH with buthionine sulfoximine reproduced the enhanced sensitivity to vanadate while preincubation of resistant cells with N-acetylcysteine (NAC) prevented it, 2) intracellular GSH was decreased in resistant cells and normalized by NAC, 3) exposure to high glucose and insulin induced an increase in reactive oxygen species, which was prevented by NAC, 4) EPR (electron paramagnetic resonance) spectroscopy showed a decreased amount of vanadyl (+4) in resistant and buthionine sulfoximine-treated cells, which correlated with decreased GSH and increased vanadate sensitivity, while total vanadium uptake was not altered, and 5) inhibition of recombinant PTP1B in vitro was more sensitive to vanadate (+5) than vanadyl (+4). In conclusion, the paradoxical increased sensitivity to vanadate in hyperglycemia-induced insulin resistant adipocytes is due to oxidative stress and decreased reduction of vanadate (+5) to vanadyl (+4). Thus, sensitivity of PTP inhibition and glucose transport to vanadate is regulated by cellular redox state.
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Affiliation(s)
- B Lu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
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