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Fu F, Liu C, Shi R, Li M, Zhang M, Du Y, Wang Q, Li J, Wang G, Pei J, Ding M. Punicalagin Protects Against Diabetic Cardiomyopathy by Promoting Opa1-Mediated Mitochondrial Fusion via Regulating PTP1B-Stat3 Pathway. Antioxid Redox Signal 2021; 35:618-641. [PMID: 33906428 DOI: 10.1089/ars.2020.8248] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Aims: This study aims to explore the efficacy of punicalagin (PG) on diabetic cardiomyopathy (DCM), with a specific focus on the mechanisms underlying the effects of PG on mitochondrial fusion/fission dynamics. Results: Cardiac structural and functional abnormalities were ameliorated in diabetic rats receiving PG administration as evidenced by increased ejection fraction, and attenuated myocardial fibrosis and hypertrophy. PG enhanced mitochondrial function and inhibited mitochondria-derived oxidative stress by promoting Opa1-mediated mitochondrial fusion. The benefits of PG could be abrogated by knockdown of Opa1 in vivo and in vitro. Inhibitor screening and chromatin immunoprecipitation analysis showed that Stat3 directly regulated the transcriptional expression of Opa1 by binding to its promoter and was responsible for PG-induced Opa1-mediated mitochondrial fusion. Moreover, pharmmapper screening and molecular docking studies revealed that PG embedded into the activity pocket of PTP1B and inhibited the activity of PTP1B. Overexpression of PTP1B blocked the promoting effect of PG on Stat3 phosphorylation and Opa1-mediated mitochondrial fusion, whereas knockdown of PTP1B mimicked the benefits of PG in high-glucose-treated cardiomyocytes. Innovation: Our study is the first to identify PG as a novel mitochondrial fusion promoter against hyperglycemia-induced mitochondrial oxidative injury and cardiomyopathy by upregulating Opa1 via regulating PTP1B-Stat3 pathway. Conclusion: PG protects against DCM by promoting Opa1-mediated mitochondrial fusion, a process in which PG interacts with PTP1B and inhibits its activity, which in turn increases Stat3 phosphorylation and then enhances the transcriptional expression of Opa1. These results suggest that PG might be a promising new therapeutic approach against diabetic cardiac complication. Antioxid. Redox Signal. 35, 618-641.
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Affiliation(s)
- Feng Fu
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Chaoyang Liu
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Rui Shi
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Man Li
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Min Zhang
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Yanyan Du
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Qiaojuan Wang
- School of Life Sciences, Northwest University, Xi'an, China.,Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Jun Li
- Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Guoen Wang
- Department of Geriatrics Cardiology, The Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, China
| | - Jianming Pei
- Department of Physiology and Pathophysiology, National Key Discipline of Cell Biology, Fourth Military Medical University, Xi'an, China
| | - Mingge Ding
- Department of Geriatrics Cardiology, The Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, China
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Thiebaut PA, Besnier M, Gomez E, Richard V. Role of protein tyrosine phosphatase 1B in cardiovascular diseases. J Mol Cell Cardiol 2016; 101:50-57. [DOI: 10.1016/j.yjmcc.2016.09.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/31/2016] [Accepted: 09/01/2016] [Indexed: 12/14/2022]
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Khodabandehloo H, Gorgani-Firuzjaee S, Panahi G, Meshkani R. Molecular and cellular mechanisms linking inflammation to insulin resistance and β-cell dysfunction. Transl Res 2016; 167:228-56. [PMID: 26408801 DOI: 10.1016/j.trsl.2015.08.011] [Citation(s) in RCA: 193] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/29/2015] [Accepted: 08/31/2015] [Indexed: 12/13/2022]
Abstract
Obesity is a major public health problem worldwide, and it is associated with an increased risk of developing type 2 diabetes. It is now commonly accepted that chronic inflammation associated with obesity induces insulin resistance and β-cell dysfunction in diabetic patients. Obesity-associated inflammation is characterized by increased abundance of macrophages and enhanced production of inflammatory cytokines in adipose tissue. Adipose tissue macrophages are suggested to be the major source of local and systemic inflammatory mediators such as tumor necrosis factor α, interleukin (IL)-1β, and IL-6. These cytokines induce insulin resistance in insulin target tissues by activating the suppressors of cytokine signaling proteins, several kinases such as c-Jun N-terminal kinase, IκB kinase β, and protein kinase C, inducible nitric oxide synthase, extracellular signal-regulated kinase, and protein tyrosine phosphatases such as protein tyrosine phosphatase 1B. These activated factors impair the insulin signaling at the insulin receptor and the insulin receptor substrates levels. The same process most likely occurs in the pancreas as it contains a pool of tissue-resident macrophages. High concentrations of glucose or palmitate via the chemokine production promote further immune cell migration and infiltration into the islets. These events ultimately induce inflammatory responses leading to the apoptosis of the pancreatic β cells. In this review, the cellular and molecular players that participate in the regulation of obesity-induced inflammation are discussed, with particular attention being placed on the roles of the molecular players linking inflammation to insulin resistance and β-cell dysfunction.
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Affiliation(s)
- Hadi Khodabandehloo
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Sattar Gorgani-Firuzjaee
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Ghodratollah Panahi
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Reza Meshkani
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran.
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González-Rodríguez Á, Santamaría B, Mas-Gutierrez JA, Rada P, Fernández-Millán E, Pardo V, Álvarez C, Cuadrado A, Ros M, Serrano M, Valverde ÁM. Resveratrol treatment restores peripheral insulin sensitivity in diabetic mice in a sirt1-independent manner. Mol Nutr Food Res 2015; 59:1431-42. [DOI: 10.1002/mnfr.201400933] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/18/2015] [Accepted: 03/20/2015] [Indexed: 12/31/2022]
Affiliation(s)
- Águeda González-Rodríguez
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM); Madrid Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII; Spain
| | - Beatriz Santamaría
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM); Madrid Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII; Spain
| | | | - Patricia Rada
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM); Madrid Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), ISCIII; Spain
| | - Elisa Fernández-Millán
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII; Spain
- Departamento de Bioquímica y Biología Molecular II; Facultad de Farmacia; Universidad Complutense de Madrid; Madrid Spain
| | - Virginia Pardo
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM); Madrid Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII; Spain
| | - Carmen Álvarez
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII; Spain
- Departamento de Bioquímica y Biología Molecular II; Facultad de Farmacia; Universidad Complutense de Madrid; Madrid Spain
| | - Antonio Cuadrado
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM); Madrid Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), ISCIII; Spain
- Instituto de Investigacion Sanitaria La Paz (IdiPaz); Madrid Spain
| | - Manuel Ros
- Facultad de Ciencias; Universidad Rey Juan Carlos; Madrid Spain
| | - Manuel Serrano
- Spanish National Cancer Research Centre (CNIO); Madrid Spain
| | - Ángela M. Valverde
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM); Madrid Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII; Spain
- Instituto de Investigacion Sanitaria La Paz (IdiPaz); Madrid Spain
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Penque BA, Hoggatt AM, Herring BP, Elmendorf JS. Hexosamine biosynthesis impairs insulin action via a cholesterolgenic response. Mol Endocrinol 2013; 27:536-47. [PMID: 23315940 DOI: 10.1210/me.2012-1213] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Plasma membrane cholesterol accumulation has been implicated in cellular insulin resistance. Given the role of the hexosamine biosynthesis pathway (HBP) as a sensor of nutrient excess, coupled to its involvement in the development of insulin resistance, we delineated whether excess glucose flux through this pathway provokes a cholesterolgenic response induced by hyperinsulinemia. Exposing 3T3-L1 adipocytes to physiologically relevant doses of hyperinsulinemia (250pM-5000pM) induced a dose-dependent gain in the mRNA/protein levels of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGR). These elevations were associated with elevated plasma membrane cholesterol. Mechanistically, hyperinsulinemia increased glucose flux through the HBP and O-linked β-N-acetylglucosamine (O-GlcNAc) modification of specificity protein 1 (Sp1), known to activate cholesterolgenic gene products such as the sterol response element-binding protein (SREBP1) and HMGR. Chromatin immunoprecipitation demonstrated that increased O-GlcNAc modification of Sp1 resulted in a higher binding affinity of Sp1 to the promoter regions of SREBP1 and HMGR. Luciferase assays confirmed that HMGR promoter activity was elevated under these conditions and that inhibition of the HBP with 6-diazo-5-oxo-l-norleucine (DON) prevented hyperinsulinemia-induced activation of the HMGR promoter. In addition, both DON and the Sp1 DNA-binding inhibitor mithramycin prevented the hyperinsulinemia-induced increases in HMGR mRNA/protein and plasma membrane cholesterol. In these mithramycin-treated cells, both cortical filamentous actin structure and insulin-stimulated glucose transport were restored. Together, these data suggest a novel mechanism whereby increased HBP activity increases Sp1 transcriptional activation of a cholesterolgenic program, thereby elevating plasma membrane cholesterol and compromising cytoskeletal structure essential for insulin action.
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Affiliation(s)
- Brent A Penque
- Departments of Cellular and Integrative Physiology, Indiana UniversitySchool of Medicine, Indianapolis, IN 46202, USA
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6
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Yang YM, Seo SY, Kim TH, Kim SG. Decrease of microRNA-122 causes hepatic insulin resistance by inducing protein tyrosine phosphatase 1B, which is reversed by licorice flavonoid. Hepatology 2012; 56:2209-20. [PMID: 22807119 DOI: 10.1002/hep.25912] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 06/07/2012] [Indexed: 12/28/2022]
Abstract
UNLABELLED Protein tyrosine phosphatase 1B (PTP1B) inhibits hepatic insulin signaling by dephosphorylating tyrosine residues in insulin receptor (IR) and insulin receptor substrate (IRS). MicroRNAs may modulate metabolic functions. In view of the lack of understanding of the regulatory mechanism of PTP1B and its chemical inhibitors, this study investigated whether dysregulation of specific microRNA causes PTP1B-mediated hepatic insulin resistance, and if so, what the underlying basis is. In high-fat-diet-fed mice or hepatocyte models with insulin resistance, the expression of microRNA-122 (miR-122), the most abundant microRNA in the liver, was substantially down-regulated among those predicted to interact with the 3'-untranslated region of PTP1B messenger RNA (mRNA). Experiments using miR-122 mimic and its inhibitor indicated that miR-122 repression caused PTP1B induction. Overexpression of c-Jun N-terminal kinase 1 (JNK1) resulted in miR-122 down-regulation with the induction of PTP1B. A dominant-negative mutant of JNK1 had the opposite effect. JNK1 facilitated inactivating phosphorylation of hepatocyte nuclear factor 4α (HNF4α) responsible for miR-122 expression, as verified by the lack of HNF4α binding to the gene promoter. The regulatory role of JNK1 in PTP1B induction by a decrease in miR-122 level was strengthened by cell-based assays using isoliquiritigenin and liquiritigenin (components in Glycyrrhizae radix) as functional JNK inhibitors; JNK inhibition enabled cells to restore IR and IRS1/2 tyrosine phosphorylation and insulin signaling against tumor necrosis factor alpha, and prevented PTP1B induction. Moreover, treatment with each of the agents increased miR-122 levels and abrogated hepatic insulin resistance in mice fed a high-fat diet, causing a glucose-lowering effect. CONCLUSION Decreased levels of miR-122 as a consequence of HNF4α phosphorylation by JNK1 lead to hepatic insulin resistance through PTP1B induction, which may be overcome by chemical inhibition of JNK.
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Affiliation(s)
- Yoon Mee Yang
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea
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7
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Protein tyrosine phosphatase 1B (PTP1B) modulates palmitate-induced cytokine production in macrophage cells. Inflamm Res 2012; 62:239-46. [DOI: 10.1007/s00011-012-0573-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 10/09/2012] [Accepted: 10/28/2012] [Indexed: 12/20/2022] Open
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MohammadTaghvaei N, Taheripak G, Taghikhani M, Meshkani R. Palmitate-induced PTP1B expression is mediated by ceramide-JNK and nuclear factor κB (NF-κB) activation. Cell Signal 2012; 24:1964-70. [DOI: 10.1016/j.cellsig.2012.04.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 04/25/2012] [Indexed: 10/28/2022]
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Abstract
Type 2 Diabetes mellitus (T2D) is the most common endocrine disorder associated to metabolic syndrome (MS) and occurs when insulin secretion can no compensate peripheral insulin resistance. Among peripheral tissues, the liver controls glucose homeostasis due to its ability to consume and produce glucose. The molecular mechanism underlying hepatic insulin resistance is not completely understood; however, it involves the impairment of the insulin signalling network. Among the critical nodes of hepatic insulin signalling, insulin receptor substrate 2 (IRS2) and protein tyrosine phosphatase 1B (PTP1B) modulate the phosphatidylinositol (PI) 3-kinase/Akt/Foxo1 pathway that controls the suppression of gluconeogenic genes. In this review, we will focus on recent findings regarding the molecular mechanism by which IRS2 and PTP1B elicit opposite effects on carbohydrate metabolism in the liver in response to insulin. Finally, we will discuss the involvement of the critical nodes of insulin signalling in non-alcoholic fatty liver disease (NAFLD) in humans.
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Affiliation(s)
- Angela M Valverde
- Instituto de Investigaciones Biomédicas Alberto Sols (CSIC/UAM), C/Arturo Duperier 4, 28029 Madrid, Spain.
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10
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Calcium as a mediator between erythropoietin and protein tyrosine phosphatase 1B. Arch Biochem Biophys 2011; 505:242-9. [DOI: 10.1016/j.abb.2010.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 09/28/2010] [Accepted: 10/02/2010] [Indexed: 01/09/2023]
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11
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González-Rodríguez Á, Gutierrez JAM, Sanz-González S, Ros M, Burks DJ, Valverde ÁM. Inhibition of PTP1B restores IRS1-mediated hepatic insulin signaling in IRS2-deficient mice. Diabetes 2010; 59:588-99. [PMID: 20028942 PMCID: PMC2828646 DOI: 10.2337/db09-0796] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Mice with complete deletion of insulin receptor substrate 2 (IRS2) develop hyperglycemia, impaired hepatic insulin signaling, and elevated gluconeogenesis, whereas mice deficient for protein tyrosine phosphatase (PTP)1B display an opposing hepatic phenotype characterized by increased sensitivity to insulin. To define the relationship between these two signaling pathways in the regulation of liver metabolism, we used genetic and pharmacological approaches to study the effects of inhibiting PTP1B on hepatic insulin signaling and expression of gluconeogenic enzymes in IRS2(-/-) mice. RESEARCH DESIGN AND METHODS We analyzed glucose homeostasis and insulin signaling in liver and isolated hepatocytes from IRS2(-/-) and IRS2(-/-)/PTP1B(-/-) mice. Additionally, hepatic insulin signaling was assessed in control and IRS2(-/-) mice treated with resveratrol, an antioxidant present in red wine. RESULTS In livers of hyperglycemic IRS2(-/-) mice, the expression levels of PTP1B and its association with the insulin receptor (IR) were increased. The absence of PTP1B in the double-mutant mice restored hepatic IRS1-mediated phosphatidylinositol (PI) 3-kinase/Akt/Foxo1 signaling. Moreover, resveratrol treatment of hyperglycemic IRS2(-/-) mice decreased hepatic PTP1B mRNA and inhibited PTP1B activity, thereby restoring IRS1-mediated PI 3-kinase/Akt/Foxo1 signaling and peripheral insulin sensitivity. CONCLUSIONS By regulating the phosphorylation state of IR, PTB1B determines sensitivity to insulin in liver and exerts a unique role in the interplay between IRS1 and IRS2 in the modulation of hepatic insulin action.
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Affiliation(s)
- Águeda González-Rodríguez
- Institute of Biomedicine Alberto Sols, Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Spain
| | | | - Silvia Sanz-González
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Spain
- Research Center Príncipe Felipe, Valencia, Spain
| | - Manuel Ros
- Faculty of Health Sciences, University Rey Juan Carlos, Madrid, Spain
| | - Deborah J. Burks
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Spain
- Research Center Príncipe Felipe, Valencia, Spain
| | - Ángela M. Valverde
- Institute of Biomedicine Alberto Sols, Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Spain
- Corresponding author: Ángela M. Valverde,
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Lessard L, Stuible M, Tremblay ML. The two faces of PTP1B in cancer. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:613-9. [PMID: 19782770 DOI: 10.1016/j.bbapap.2009.09.018] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 09/11/2009] [Accepted: 09/18/2009] [Indexed: 10/25/2022]
Abstract
PTP1B is a classical non-transmembrane protein tyrosine phosphatase that plays a key role in metabolic signaling and is a promising drug target for type 2 diabetes and obesity. Accumulating evidence also indicates that PTP1B is involved in cancer, but contrasting findings suggest that it can exert both tumor suppressing and tumor promoting effects depending on the substrate involved and the cellular context. In this review, we will discuss the diverse mechanisms by which PTP1B may influence tumorigenesis as well as recent in vivo data on the impact of PTP1B deficiency in murine cancer models. Together, these results highlight not only the great potential of PTP1B inhibitors in cancer therapy but also the need for a better understanding of PTP1B function prior to use of these compounds in human patients.
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Affiliation(s)
- Laurent Lessard
- Goodman Cancer Centre and Department of Biochemistry, McGill University, 1160 Pine Avenue, Montréal, Québec, Canada H3G 0B1
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Wang N, Zhang D, Mao X, Zou F, Jin H, Ouyang J. Astragalus polysaccharides decreased the expression of PTP1B through relieving ER stress induced activation of ATF6 in a rat model of type 2 diabetes. Mol Cell Endocrinol 2009; 307:89-98. [PMID: 19524131 DOI: 10.1016/j.mce.2009.03.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 12/03/2008] [Accepted: 03/02/2009] [Indexed: 11/16/2022]
Abstract
Protein tyrosine phosphatase 1B (PTP1B) was considered as a potential therapeutic target of type 2 diabetes (T2DM) because of its negative regulation of insulin signaling. It located on the cytosolic surface of endoplasmic reticulum (ER) and played an essential role in the ER stress signaling. Activating transcription factor 6 (ATF6) was an ER stress regulated transmembrane transcription factor that activated the transcription of ER molecular chaperones. We hypothesized that the expression of PTP1B may be regulated by ATF6 when ER stress happened. Our previous studies showed that Astragalus polysaccharide (APS) increased the insulin sensitivity through decreasing the overexpression of PTP1B in T2DM animal models. In this study, we intended to investigate the possible mechanisms involved in this effect. A rat model of T2DM was established using high fat diet associated with intraperitoneal injection of 25 mg/kg streptozocin; 25 mmol/l D-glucose and 5x10(-7) mol/l insulin were used as in vitro investigations to mimic T2DM-like environment. 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF) and pCI-Flag-ATF6(N)(2-366) plasmid were treated separately on human hepatocyte line HL-7702 to observe the effect of ATF6 on the expression of PTP1B. The results suggested that APS not only restored the glucose homeostasis but also reduced the ER stress in this rat model of T2DM; ATF6 was involved in mediating the expression of PTP1B when ER stress happened; APS decreased the expression of PTP1B at least partly through inhibiting the activation of ATF6.
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Affiliation(s)
- Nian Wang
- Department of Pathophysiology, Medical College of Wuhan University, Hubei Provincial Key Laboratory of Allergy and Immune-Related Diseases, Wuhan, People's Republic of China
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