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Gogiraju R, Gachkar S, Velmeden D, Bochenek ML, Zifkos K, Hubert A, Münzel T, Offermanns S, Schäfer K. Protein Tyrosine Phosphatase 1B Deficiency in Vascular Smooth Muscle Cells Promotes Perivascular Fibrosis following Arterial Injury. Thromb Haemost 2022; 122:1814-1826. [PMID: 36075234 PMCID: PMC9512587 DOI: 10.1055/s-0042-1755329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Background
Smooth muscle cell (SMC) phenotype switching plays a central role during vascular remodeling. Growth factor receptors are negatively regulated by protein tyrosine phosphatases (PTPs), including its prototype PTP1B. Here, we examine how reduction of PTP1B in SMCs affects the vascular remodeling response to injury.
Methods
Mice with inducible PTP1B deletion in SMCs (SMC.PTP1B-KO) were generated by crossing mice expressing Cre.ER
T2
recombinase under the
Myh11
promoter with PTP1B
flox/flox
mice and subjected to FeCl
3
carotid artery injury.
Results
Genetic deletion of PTP1B in SMCs resulted in adventitia enlargement, perivascular SMA
+
and PDGFRβ
+
myofibroblast expansion, and collagen accumulation following vascular injury. Lineage tracing confirmed the appearance of
Myh11
-Cre reporter cells in the remodeling adventitia, and SCA1
+
CD45
-
vascular progenitor cells increased. Elevated mRNA expression of transforming growth factor β (TGFβ) signaling components or enzymes involved in extracellular matrix remodeling and TGFβ liberation was seen in injured SMC.PTP1B-KO mouse carotid arteries, and mRNA transcript levels of contractile SMC marker genes were reduced already at baseline. Mechanistically, Cre recombinase (mice) or siRNA (cells)-mediated downregulation of PTP1B or inhibition of ERK1/2 signaling in SMCs resulted in nuclear accumulation of KLF4, a central transcriptional repressor of SMC differentiation, whereas phosphorylation and nuclear translocation of SMAD2 and SMAD3 were reduced. SMAD2 siRNA transfection increased protein levels of PDGFRβ and MYH10 while reducing ERK1/2 phosphorylation, thus phenocopying genetic PTP1B deletion.
Conclusion
Chronic reduction of PTP1B in SMCs promotes dedifferentiation, perivascular fibrosis, and adverse remodeling following vascular injury by mechanisms involving an ERK1/2 phosphorylation-driven shift from SMAD2 to KLF4-regulated gene transcription.
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Affiliation(s)
- Rajinikanth Gogiraju
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany
| | - Sogol Gachkar
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany
| | - David Velmeden
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany
| | - Magdalena L Bochenek
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany.,Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Konstantinos Zifkos
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
| | - Astrid Hubert
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany
| | - Thomas Münzel
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Rhine-Main Site, Mainz, Germany
| | - Stefan Offermanns
- Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany.,Centre for Molecular Medicine, Medical Faculty, JW Goethe University Frankfurt, Frankfurt, Germany.,Cardiopulmonary Institute (CPI), Frankfurt, Germany.,German Center for Cardiovascular Research (DZHK e.V.), Rhine-Main Site, Frankfurt and Bad Nauheim, Germany
| | - Katrin Schäfer
- Department of Cardiology, Cardiology I, University Medical Center Mainz, Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Rhine-Main Site, Mainz, Germany
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2
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Hamel-Côté G, Gendron D, Rola-Pleszczynski M, Stankova J. Regulation of platelet-activating factor-mediated protein tyrosine phosphatase 1B activation by a Janus kinase 2/calpain pathway. PLoS One 2017; 12:e0180336. [PMID: 28686728 PMCID: PMC5501562 DOI: 10.1371/journal.pone.0180336] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 06/14/2017] [Indexed: 11/18/2022] Open
Abstract
Atherosclerosis is a pro-inflammatory condition underlying many cardiovascular diseases. Platelet-activating factor (PAF) and interleukin 6 (IL-6) are actively involved in the onset and progression of atherosclerotic plaques. The involvement of monocyte-derived macrophages is well characterized in the installation of inflammatory conditions in the plaque, but less is known about the contribution of monocyte-derived dendritic cells (Mo-DCs). In the same way, the involvement of calcium, phospholipase C and A2 in PAF-induced IL-6 production, in different cells types, has been shown; however, the importance of the Jak/STAT pathway and its regulation by protein-tyrosine phosphatases in this response have not been addressed. In this study, we report that PAF stimulates PTP1B activity via Jak2, thereby modulating PAF-induced IL-6 production. Using HEK 293 cells stably transfected with the PAF receptor in order to discriminate the pathway components, our results suggest that Jak2 modulates PAF-induced IL-6 production via both positive and negative pathways. Jak2 kinase activity was necessary for maximal transactivation of the IL-6 promoter, as seen by luciferase assays, whereas the same kinase also downregulated this promoter transactivation through the activation of a calcium/calpain/PTP1B pathway. The same pathways were operational in monocyte-derived dendritic cells, since PAF-induced PTP1B activation negatively regulated PAF-induced IL-6 mRNA production and, in addition, Jak2 activated calpain, one of the components involved in PAF-induced PTP1B activation. Results obtained in this study indicate that Jak2 activation is important for maximal IL-6 promoter transactivation by PAF and that PTP1B is involved in the negative regulation of this transactivation. However, PTP1B does not directly regulate Jak2 activation, but rather Jak2 regulates PAF-induced PTP1B activation.
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Affiliation(s)
- Geneviève Hamel-Côté
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Daniel Gendron
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Marek Rola-Pleszczynski
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Jana Stankova
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
- * E-mail:
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3
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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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4
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Zhuang D, Balani P, Pu Q, Thakran S, Hassid A. Suppression of PKG by PDGF or nitric oxide in differentiated aortic smooth muscle cells: obligatory role of protein tyrosine phosphatase 1B. Am J Physiol Heart Circ Physiol 2010; 300:H57-63. [PMID: 21057040 DOI: 10.1152/ajpheart.00225.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Treatment of aortic smooth muscle cells with PDGF induces the upregulation of protein tyrosine phosphatase 1B (PTP1B). PTP1B, in turn, decreases the function of several growth factor receptors, thus completing a negative feedback loop. Studies have reported that PDGF induces the downregulation of PKG as part of a repertoire of dedifferentiation of vascular smooth muscle cells. Other studies have reported that chronic nitric oxide (NO) treatment also induces the downregulation of PKG. In the present study, we tested the hypothesis that the downregulation of PKG by PDGF or NO in differentiated rat aortic smooth muscle cells can be attributed to the upregulation of PTP1B. We found that treatment with PDGF or NO induced an upregulation of PTP1B levels. Overexpression of PTP1B induced a marked downregulation of PKG mRNA and protein levels, whereas the expression of dominant negative PTP1B or short interfering RNA directed against PTP1B blocked the capacity of PDGF or NO to decrease PKG levels. We conclude that the upregulation of PTP1B by PDGF or NO is both necessary and sufficient to induce the downregulation of PKG via an effect on PKG mRNA levels.
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Affiliation(s)
- Daming Zhuang
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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5
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Pu Q, Zhuang D, Thakran S, Hassid A. Mechanisms related to NO-induced motility in differentiated rat aortic smooth muscle cells. Am J Physiol Heart Circ Physiol 2010; 300:H101-8. [PMID: 21037226 DOI: 10.1152/ajpheart.00342.2010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) is thought to play an important role as an inhibitor of vascular cell proliferation, motility, and neointima formation. This effect is mediated, in part, via the upregulation of protein tyrosine phosphatase (PTP)1B. Conversely, studies have reported that in presumably hyperinsulinemic mice fed a high-fat diet, NO enhances vascular remodeling, whereas a deficit of NO attenuates vascular remodeling. We have reported that in differentiated cultured smooth muscle cells treated with insulin, NO induces a motogenic effect that is dependent on Src homology-2 domain PTP 2 (SHP2) upregulation. In the present study, we describe novel mechanisms relevant to the motogenic effect of NO. Treatment of cultured cells with the selective angiontensin type 1 receptor antagonist losartan, but not with the selective angiotensin type 2 receptor antagonist PD-123319, blocked the comotogenic capacity of NO and insulin. Insulin and NO increased the secretion of ANG II into the culture media by 2- and 2.5-fold (P < 0.05), respectively, whereas treatment of cells with ANG II uncovered the motogenic effect of NO (1.4-fold above control, P < 0.05) and decreased the levels of PTP1B to 45% of control (P < 0.05). Suppression of PTP1B function was sufficient to uncover the motogenic effect of NO. The capacity of insulin to suppress PTP1B activity was blocked by losartan, implicating ANG II function in mediating this effect. Both insulin and ANG II induced the upregulation of phosphatidyl inositol 3-kinase (PI3K)-δ by two- to threefold (P < 0.05), and this effect was both necessary and sufficient to uncover NO-induced motogenesis. Finally, suppression of PTP1B function potentiated, whereas overexpression of PTP1B inhibited, SHP2-induced motogenesis. These results support the hypothesis that the comotogenic effect of insulin and NO occurs via an ANG II-mediated effect involving the suppression of PTP1B and upregulation of PI3K-δ and SHP2.
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Affiliation(s)
- Qinghua Pu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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6
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Postprocedure Administration of Insulin in Canine Autologous Vein Grafting: A Potential Strategy to Attenuate Intimal Hyperplasia. J Cardiovasc Pharmacol 2010; 56:402-12. [DOI: 10.1097/fjc.0b013e3181f09ba8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Varu VN, Ahanchi SS, Hogg ME, Bhikhapurwala HA, Chen A, Popowich DA, Vavra AK, Martinez J, Jiang Q, Saavedra JE, Hrabie JA, Keefer LK, Kibbe MR. Insulin enhances the effect of nitric oxide at inhibiting neointimal hyperplasia in a rat model of type 1 diabetes. Am J Physiol Heart Circ Physiol 2010; 299:H772-9. [PMID: 20562340 PMCID: PMC2944486 DOI: 10.1152/ajpheart.01234.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 06/17/2010] [Indexed: 11/22/2022]
Abstract
Diabetes confers greater restenosis from neointimal hyperplasia following vascular interventions. While localized administration of nitric oxide (NO) is known to inhibit neointimal hyperplasia, the effect of NO in type 1 diabetes is unknown. Thus the aim of this study was to determine the efficacy of NO following arterial injury, with and without exogenous insulin administration. Vascular smooth muscle cells (VSMC) from lean Zucker (LZ) rats were exposed to the NO donor, DETA/NO, following treatment with different glucose and/or insulin concentrations. DETA/NO inhibited VSMC proliferation in a concentration-dependent manner to a greater extent in VSMC exposed to normal-glucose vs. high-glucose environments, and even more effectively in normal-glucose/high-insulin and high-glucose/high-insulin environments. G(0)/G(1) cell cycle arrest and cell death were not responsible for the enhanced efficacy of NO in these environments. Next, type 1 diabetes was induced in LZ rats with streptozotocin. The rat carotid artery injury model was performed. Type 1 diabetic rats experienced no significant reduction in neointimal hyperplasia following arterial injury and treatment with the NO donor PROLI/NO. However, daily administration of insulin to type 1 diabetic rats restored the efficacy of NO at inhibiting neointimal hyperplasia (60% reduction, P < 0.05). In conclusion, these data demonstrate that NO is ineffective at inhibiting neointimal hyperplasia in an uncontrolled rat model of type 1 diabetes; however, insulin administration restores the efficacy of NO at inhibiting neointimal hyperplasia. Thus insulin may play a role in regulating the downstream beneficial effects of NO in the vasculature.
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MESH Headings
- Analysis of Variance
- Animals
- Aorta/drug effects
- Aorta/metabolism
- Aorta/pathology
- Carotid Arteries/drug effects
- Carotid Arteries/metabolism
- Carotid Arteries/pathology
- Cell Death/drug effects
- Cell Proliferation/drug effects
- Cells, Cultured
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Drug Interactions
- Flow Cytometry
- Hyperplasia/metabolism
- Hyperplasia/pathology
- Insulin/metabolism
- Insulin/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- Nitric Oxide/metabolism
- Nitric Oxide/pharmacology
- Rats
- Tunica Intima/drug effects
- Tunica Intima/metabolism
- Tunica Intima/pathology
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Affiliation(s)
- Vinit N Varu
- Division of Vascular Surgery and Institute for BioNanotechnology in Medicine, Northwestern University, Chicago, IL 60611, USA
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8
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Grissa O, Yessoufou A, Mrisak I, Hichami A, Amoussou-Guenou D, Grissa A, Djrolo F, Moutairou K, Miled A, Khairi H, Zaouali M, Bougmiza I, Zbidi A, Tabka Z, Khan NA. Growth factor concentrations and their placental mRNA expression are modulated in gestational diabetes mellitus: possible interactions with macrosomia. BMC Pregnancy Childbirth 2010; 10:7. [PMID: 20144210 PMCID: PMC2830966 DOI: 10.1186/1471-2393-10-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Accepted: 02/09/2010] [Indexed: 12/21/2022] Open
Abstract
Background Gestational diabetes mellitus (GDM) is a form of diabetes that occurs during pregnancy. GDM is a well known risk factor for foetal overgrowth, termed macrosomia which is influenced by maternal hypergycemia and endocrine status through placental circulation. The study was undertaken to investigate the implication of growth factors and their receptors in GDM and macrosomia, and to discuss the role of the materno-foeto-placental axis in the in-utero regulation of foetal growth. Methods 30 women with GDM and their 30 macrosomic babies (4.75 ± 0.15 kg), and 30 healthy age-matched pregnant women and their 30 newborns (3.50 ± 0.10 kg) were recruited in the present study. Serum concentrations of GH and growth factors, i.e., IGF-I, IGF-BP3, FGF-2, EGF and PDGF-B were determined by ELISA. The expression of mRNA encoding for GH, IGF-I, IGF-BP3, FGF-2, PDGF-B and EGF, and their receptors, i.e., GHR, IGF-IR, FGF-2R, EGFR and PDGFR-β were quantified by using RT-qPCR. Results The serum concentrations of IGF-I, IGF-BP3, EGF, FGF-2 and PDGF-B were higher in GDM women and their macrosomic babies as compared to their respective controls. The placental mRNA expression of the growth factors was either upregulated (FGF-2 or PDGF-B) or remained unaltered (IGF-I and EGF) in the placenta of GDM women. The mRNA expression of three growth factor receptors, i.e., IGF-IR, EGFR and PDGFR-β, was upregulated in the placenta of GDM women. Interestingly, serum concentrations of GH were downregulated in the GDM women and their macrosomic offspring. Besides, the expression of mRNAs encoding for GHR was higher, but that encoding for GH was lower, in the placenta of GDM women than control women. Conclusions Our results demonstrate that growth factors might be implicated in GDM and, in part, in the pathology of macrosomia via materno-foeto-placental axis.
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Affiliation(s)
- Oussama Grissa
- University of Burgundy, UPRES EA4183 Lipids and Cell Signaling, Faculty of Life Sciences, Dijon, France
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9
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Popov D. Vascular PTPs: current developments and challenges for exploitation in Type 2 diabetes-associated vascular dysfunction. Biochem Biophys Res Commun 2009; 389:1-4. [PMID: 19715673 DOI: 10.1016/j.bbrc.2009.08.110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 08/21/2009] [Indexed: 12/21/2022]
Abstract
Protein Tyrosine Phosphatases (PTPs) are important contributors to vascular cells normal function, by balancing signaling proteins activation exerted by phosphorylating kinases. Type 2 diabetes related insults, such as hyperglycemia, oxidative stress, and insulin resistance disturb the phosphorylation/dephosphorylation equilibrium towards an abnormal augmented phosphorylation of signaling proteins associated with changes in PTPs expression, enzymatic activity and interaction with cellular substrates. We briefly review here: (i) the new findings on receptor and non-receptor PTPs and their role in vascular cells, (ii) several data on oxidation and phosphorylation of these molecules in endothelial and smooth muscle cells, (iii) vascular PTPs intrinsic activity and dysregulation under the insults of diabetic milieu, and (iv) the potential use of PTPs and their inhibitors as therapeutic targets in Type 2 diabetes-associated vascular dysfunction.
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Affiliation(s)
- Doina Popov
- Institute of Cellular Biology and Pathology N. Simionescu, 050568 Bucharest, Romania.
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10
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Popov D, Nemecz M, Dumitrescu M, Georgescu A, Böhmer FD. Long-term high glucose concentration influences Akt, ERK1/2, and PTP1B protein expression in human aortic smooth muscle cells. Biochem Biophys Res Commun 2009; 388:51-5. [PMID: 19647719 DOI: 10.1016/j.bbrc.2009.07.141] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 07/22/2009] [Indexed: 11/26/2022]
Abstract
Hyperglycemia stimulates a plethora of intracellular signaling pathways within the cells of the vascular wall resulting in dysfunction-associated pathologies. Most of the studies reported so far explored the effect of rather short-time exposure of smooth muscle cells to high glucose concentrations. To mimic situation in Type 2 diabetes in which vascular wall is constantly exposed to circulating hyperglycemia, we report here the long-term (7days) effect of high glucose concentration on human media artery smooth muscle cells. This consists in up-regulation of PTP1B protein expression, down-regulation of basal Akt phosphorylation, and elevation of basal ERK1/2 activation. Acute stimulation of cells in high glucose with insulin down-regulated PTP1B expression, slightly decreased ERK1/2 activity, and activated Akt, whereas oxidative stress up-regulated Akt and ERK1/2 phosphorylation. In conclusion, long-term high glucose and acute oxidative stress and insulin stimulation imbalance the expression of activated kinases Akt and ERK1/2 and of dephosphorylating PTP1B in the insulin signaling pathway.
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Affiliation(s)
- Doina Popov
- Institute of Cellular Biology and Pathology "N. Simionescu", Bucharest, Romania.
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11
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Micke P, Hackbusch D, Mercan S, Stawowy P, Tsuprykov O, Unger T, Östman A, Kappert K. Regulation of tyrosine phosphatases in the adventitia during vascular remodelling. Biochem Biophys Res Commun 2009; 382:678-84. [DOI: 10.1016/j.bbrc.2009.03.078] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 03/12/2009] [Indexed: 10/21/2022]
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12
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Pu Q, Chang Y, Zhang C, Cai Y, Hassid A. Chronic insulin treatment suppresses PTP1B function, induces increased PDGF signaling, and amplifies neointima formation in the balloon-injured rat artery. Am J Physiol Heart Circ Physiol 2008; 296:H132-9. [PMID: 19011046 DOI: 10.1152/ajpheart.00370.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We tested the hypothesis that hyperinsulinemia induces the suppression of protein tyrosine phosphatase 1B (PTP1B) function, leading to enhanced PDGF receptor (PDGFR) signaling and neointimal hyperplasia. Rats were implanted with insulin-releasing pellets or sham pellets. Blood glucose levels, insulin levels, food and water intake, body weights, and blood pressures were measured. Neointimal hyperplasia was assessed by computerized morphometry 14 days after carotid balloon injury. PTP1B protein expression in injured arteries was determined via Western blot analysis, whereas PTP1B activity was determined via an immunophosphatase assay. Serum insulin levels were two- to threefold greater in hyperinsulinemic rats, whereas systolic blood pressures, food and water intake, serum triglyceride levels, plasma cortisol levels, and urinary catecholamine levels were not affected. Fourteen days after injury, neointima-to-media area ratios were 0.89 +/- 0.23 and 1.35 +/- 0.22 in control and hyperinsulinemic rats, respectively (P < 0.01). PTP1B protein levels and total PTP1B activity in injured carotid arteries from the insulin-treated group were significantly decreased 7 or 14 days after injury, whereas PTP1B specific activity was decreased only 14 days after injury. These findings were associated with decreased PTP1B mRNA levels and increased PDGFR tyrosyl phosphorylation in insulin-treated rats. These observations support the hypothesis that hyperinsulinemia induces the suppression of PTP1B function, leading to enhanced PDGFR signaling and neointimal hyperplasia.
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Affiliation(s)
- Qinghua Pu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
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