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Selvaraj K, Katare DP, Chand S, Chaudhary N. Trachyspermum ammi and Cinnamomum verum as nutraceuticals: Spices rich in therapeutically significant protein tyrosine phosphatases. J Food Biochem 2021; 45:e13750. [PMID: 33954990 DOI: 10.1111/jfbc.13750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/05/2021] [Accepted: 04/19/2021] [Indexed: 11/29/2022]
Abstract
Nutraceuticals need special attention as preventive molecules to create a natural barrier against various dreadful diseases like cancer and to regulate metabolism. In the present study, two spices, Trachyspermum ammi and Cinnamomum verum, been identified as excellent Protein Tyrosine Phosphatases (PTPases) sources that play significant role in the regulation of cell signal transduction and developmental processes in plants as well as animals, being lucrative and potential targets for pharmacological modulation. PTPases from both cases were partially purified into 0%-40% and 40%-80% fractions based on ammonium sulfate saturation levels. Fraction (40%-80%) exhibited a purification level of 4.44-fold and 2.86-fold with specific activity of 44.06 and 23.33 U/mg for PTPases from T. ammi and C. verum, respectively. PTPases being found to be thermally stable up to 70°C imply their industrial significance. Kinetic studies showed Km values to be 7.14 and 8.33 mM, whereas the activation energy (Ea ) values were 25.89 and 29.13 kJ/mol, respectively. Divalent cations: Cu2+ , Zn2+ , and Mn2+ acted as inhibitors of PTPases, from both sources. The Ki values of inhibitors varied from 0.014-0.125 mM in the descending order Cu2+ > Zn2+ > Mn2+ and Mn2+ > Cu2+ > Zn2+ for PTPases from T. ammi and C. verum, respectively. The inhibitory effect of sodium metavanadate aligns with prominent PTPase characteristics. In addition to these properties, the thermostability of PTPases from two spices enhances their significance in industries with therapeutically vital products. Although the source of PTPases is culinary spices, further studies are required to establish the utilization of PTPases as nutraceuticals and in therapeutic formulations. PRACTICAL APPLICATIONS: For a healthy lifestyle, awareness needs to be created by humankind towards food habits to minimize illnesses. Numerous studies have explored the consumption of nutraceutical products acts as a natural barrier and immune booster for various human ailments including SARS-COV-2. PTPases play important roles in regulating intracellular signaling and, ultimately, biological function along with their structural features. The importance of PTPases and their inhibitors has been implicated in various diseases like cancer, diabetes, and obesity. Further investigations need to be undertaken to explore the therapeutic properties of PTPases in both in vivo and in vitro for their clinical significance.
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Affiliation(s)
- Kanagarethinam Selvaraj
- Centre for Biotechnology and Biochemical Engineering, Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Deepshikha Pande Katare
- Centre for Biotechnology and Biochemical Engineering, Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Subhash Chand
- Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, India
| | - Nidhee Chaudhary
- Centre for Biotechnology and Biochemical Engineering, Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
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Castro-Sanchez P, Teagle AR, Prade S, Zamoyska R. Modulation of TCR Signaling by Tyrosine Phosphatases: From Autoimmunity to Immunotherapy. Front Cell Dev Biol 2020; 8:608747. [PMID: 33425916 PMCID: PMC7793860 DOI: 10.3389/fcell.2020.608747] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/18/2020] [Indexed: 02/06/2023] Open
Abstract
Early TCR signaling is dependent on rapid phosphorylation and dephosphorylation of multiple signaling and adaptor proteins, leading to T cell activation. This process is tightly regulated by an intricate web of interactions between kinases and phosphatases. A number of tyrosine phosphatases have been shown to modulate T cell responses and thus alter T cell fate by negatively regulating early TCR signaling. Mutations in some of these enzymes are associated with enhanced predisposition to autoimmunity in humans, and mouse models deficient in orthologous genes often show T cell hyper-activation. Therefore, phosphatases are emerging as potential targets in situations where it is desirable to enhance T cell responses, such as immune responses to tumors. In this review, we summarize the current knowledge about tyrosine phosphatases that regulate early TCR signaling and discuss their involvement in autoimmunity and their potential as targets for tumor immunotherapy.
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Affiliation(s)
- Patricia Castro-Sanchez
- Ashworth Laboratories, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Alexandra R Teagle
- Ashworth Laboratories, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Sonja Prade
- Ashworth Laboratories, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Rose Zamoyska
- Ashworth Laboratories, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
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Fu W, Sun H, Zhao Y, Chen M, Yang X, Liu Y, Jin W. BCAP31 drives TNBC development by modulating ligand-independent EGFR trafficking and spontaneous EGFR phosphorylation. Am J Cancer Res 2019; 9:6468-6484. [PMID: 31588230 PMCID: PMC6771250 DOI: 10.7150/thno.35383] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/27/2019] [Indexed: 12/14/2022] Open
Abstract
Identification of novel targets for triple-negative breast cancer (TNBC) is an urgent task as targeted therapies have increased the lifespans of Oestrogen Receptor +/ Progesterone Receptor + and HER2+ cancer patients. Methods: genes involved in protein processing in the endoplasmic reticulum, which have been reported to be key players in cancer, were used in loss-of-function screening to evaluate the oncogenic roles of these genes to identify candidate target genes in TNBC. In vitro and in vivo function assays as well as clinical prognostic analysis were used to study the oncogenic role of the gene. Molecular and cell based assays were further employed to investigate the mechanisms. Results: B Cell Receptor Associated Protein 31 (BCAP31), the expression of which is correlated with early recurrence and poor survival among patients, was identified an oncogene in our assay. In vitro studies further suggested that BCAP31 acts as a key oncogene by promoting TNBC development. We also showed that BCAP31 interacts with epidermal growth factor receptor (EGFR) and serves as an inhibitor of ligand-independent EGFR recycling, sustaining EGFR autophosphorylation and activation of downstream signalling. Conclusion: These findings reveal the functional role of BCAP31, an ER-related protein, in EGFR dysregulation and TNBC development.
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Hon J, Hwang MS, Charnetzki MA, Rashed IJ, Brady PB, Quillin S, Makinen MW. Kinetic characterization of the inhibition of protein tyrosine phosphatase-1B by Vanadyl (VO 2+) chelates. J Biol Inorg Chem 2017; 22:1267-1279. [PMID: 29071441 PMCID: PMC5671894 DOI: 10.1007/s00775-017-1500-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 10/12/2017] [Indexed: 10/18/2022]
Abstract
Protein tyrosine phosphatases (PTPases) are a prominent focus of drug design studies because of their roles in homeostasis and disorders of metabolism. These studies have met with little success because (1) virtually all inhibitors hitherto exhibit only competitive behavior and (2) a consensus sequence H/V-C-X5-R-S/T characterizes the active sites of PTPases, leading to low specificity of active site directed inhibitors. With protein tyrosine phosphatase-1B (PTP1B) identifed as the target enzyme of the vanadyl (VO2+) chelate bis(acetylacetonato)oxidovanadium(IV) [VO(acac)2] in 3T3-L1 adipocytes [Ou et al. J Biol Inorg Chem 10: 874-886, 2005], we compared the inhibition of PTP1B by VO(acac)2 with other VO2+-chelates, namely, bis(2-ethyl-maltolato)oxidovanadium(IV) [VO(Et-malto)2] and bis(3-hydroxy-2-methyl-4(1H)pyridinonato)oxidovanadium(IV) [VO(mpp)2] under steady-state conditions, using the soluble portion of the recombinant human enzyme (residues 1-321). Our results differed from those of previous investigations because we compared inhibition in the presence of the nonspecific substrate p-nitrophenylphosphate and the phosphotyrosine-containing undecapeptide DADEpYLIPQQG mimicking residues 988-998 of the epidermal growth factor receptor, a relevant, natural substrate. While VO(Et-malto)2 acts only as a noncompetitive inhibitor in the presence of either subtrate, VO(acac)2 exhibits classical uncompetitive inhibition in the presence of DADEpYLIPQQG but only apparent competitive inhibition with p-nitrophenylphosphate as substrate. Because uncompetitive inhibitors are more potent pharmacologically than competitive inhibitors, structural characterization of the site of uncompetitive binding of VO(acac)2 may provide a new direction for design of inhibitors for therapeutic purposes. Our results suggest also that the true behavior of other inhibitors may have been masked when assayed with only p-nitrophenylphosphate as substrate.
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Affiliation(s)
- Jason Hon
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA
| | - Michelle S Hwang
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA
| | - Meara A Charnetzki
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA
| | - Issra J Rashed
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA
| | - Patrick B Brady
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA
| | - Sarah Quillin
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA
| | - Marvin W Makinen
- Department of Biochemistry and Molecular Biology Center for Integrative Science, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, USA.
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Chapter Six - The Ubiquitin Network in the Control of EGFR Endocytosis and Signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:225-76. [DOI: 10.1016/bs.pmbts.2016.03.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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6
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Baumdick M, Brüggemann Y, Schmick M, Xouri G, Sabet O, Davis L, Chin JW, Bastiaens PIH. EGF-dependent re-routing of vesicular recycling switches spontaneous phosphorylation suppression to EGFR signaling. eLife 2015; 4. [PMID: 26609808 PMCID: PMC4716840 DOI: 10.7554/elife.12223] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 11/25/2015] [Indexed: 11/17/2022] Open
Abstract
Autocatalytic activation of epidermal growth factor receptor (EGFR) coupled to dephosphorylating activity of protein tyrosine phosphatases (PTPs) ensures robust yet diverse responses to extracellular stimuli. The inevitable tradeoff of this plasticity is spontaneous receptor activation and spurious signaling. We show that a ligand-mediated switch in EGFR trafficking enables suppression of spontaneous activation while maintaining EGFR’s capacity to transduce extracellular signals. Autocatalytic phosphorylation of tyrosine 845 on unliganded EGFR monomers is suppressed by vesicular recycling through perinuclear areas with high PTP1B activity. Ligand-binding results in phosphorylation of the c-Cbl docking tyrosine and ubiquitination of the receptor. This secondary signal relies on EGF-induced EGFR self-association and switches suppressive recycling to directional trafficking. The re-routing regulates EGFR signaling response by the transit-time to late endosomes where it is switched-off by high PTP1B activity. This ubiquitin-mediated switch in EGFR trafficking is a uniquely suited solution to suppress spontaneous activation while maintaining responsiveness to EGF. DOI:http://dx.doi.org/10.7554/eLife.12223.001 In living tissue, the ability of individual cells to grow is influenced by signal molecules in the environment around each cell. For example, after an injury, a molecule called epidermal growth factor can stimulate cells to grow to repair the wound. Epidermal growth factor binds to and activates a receptor protein called EGFR, which faces outwards from the cell surface. However, this signal needs to be switched off again afterwards to prevent the cells from growing too much. Epidermal growth factor activates EGFR by triggering a process called “autophosphorylation”, in which EGFR attaches molecules called phosphates to itself. To quench the signal, EGFRs that are bound to growth factors are removed from the cell surface and taken into the cell in small membrane bubbles called vesicles. Enzymes called phosphatases near the cell nucleus remove the phosphate groups and thereby switch the receptors off, before the receptors are ultimately destroyed. However, EGFR autophosphorylation can also happen spontaneously in the absence of growth factor, so it was not clear how the cell is able to distinguish between this spontaneous activation and a genuine signal. Baumdick, Brüggemann, Schmick, Xouri et al. used biochemical techniques to address this question. The experiments show that EGFRs that have become spontaneously active are also removed from the cell surface in vesicles. However, unlike the EGFRs that are bound to growth factors, the spontaneously active receptors are recycled back to the membrane. On the way, their activity is also switched off by encountering phosphatases so that they are not active when they reach the cell surface again. The experiments also show that EGFRs are targeted for destruction by the presence of a tag called ubiquitin, which is added to the receptor in response to the binding of growth factor. Therefore, Baumdick et al.’s findings show that epidermal growth factor controls a switch that alters the way active EGFRs are processed in cells. This system acts to suppress the spontaneous activation of EGFRs, whilst maintaining the ability of the cell to respond to epidermal growth factor. The next challenge is to understand how the location of the phosphatases inside the cell influences when and how the EGFRs respond to this external signal. DOI:http://dx.doi.org/10.7554/eLife.12223.002
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Affiliation(s)
- Martin Baumdick
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Yannick Brüggemann
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Faculty of Chemistry and Chemical Biology, Technical University of Dortmund, Dortmund, Germany
| | - Malte Schmick
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Georgia Xouri
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Ola Sabet
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Lloyd Davis
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Philippe I H Bastiaens
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Faculty of Chemistry and Chemical Biology, Technical University of Dortmund, Dortmund, Germany
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Li Z, Wang Z, Peng G, Yin Y, Zhao H, Cao Y, Xia Y. Purification and Characterization of a Novel Thermostable Extracellular Protein Tyrosine Phosphatase fromMetarhizium anisopliaeStrain CQMa102. Biosci Biotechnol Biochem 2014; 70:1961-8. [PMID: 16926509 DOI: 10.1271/bbb.60136] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An extracellular phosphatase was purified to homogeneity from the entomopathogenic fungus Metarhizium anisopliae with a 41.0% yield. The molecular mass and isoelectric point of the purified enzyme were about 82.5 kDa and 9.5 respectively. The optimum pH and temperature were about 5.5 and 75 degrees C when using O-phospho-L-tyrosine as substrate. The protein displayed high stability in a pH range 3.0-9.5 at 30 degrees C and was remarkably thermostable at 70 degrees C. The purified enzyme showed high activity on O-phospho-L-tyrosine and protein tyrosine phosphatase substrate monophosphate (a specific substrate of protein tyrosine phosphatase). Although one peptide of the phosphatase shared identity with one alkaline phosphatase of Neurospora crassa, its substrate specificity and inhibitor sensitivity indicate that the enzyme is a protein tyrosine phosphatase.
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Affiliation(s)
- Zhenlun Li
- Genetic Engineering Research Center, Bioengineering College, Chongqing University, R. P. China
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Chen Z, Sun X, Shen S, Zhang H, Ma X, Liu J, Kuang S, Yu Q. Wedelolactone, a naturally occurring coumestan, enhances interferon-γ signaling through inhibiting STAT1 protein dephosphorylation. J Biol Chem 2013; 288:14417-14427. [PMID: 23580655 DOI: 10.1074/jbc.m112.442970] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signal transducers and activators of transcription 1 (STAT1) transduces signals from cytokines and growth factors, particularly IFN-γ, and regulates expression of genes involved in cell survival/death, proliferation, and migration. STAT1 is activated through phosphorylation on its tyrosine 701 by JAKs and is inactivated through dephosphorylation by tyrosine phosphatases. We discovered a natural compound, wedelolactone, that increased IFN-γ signaling by inhibiting STAT1 dephosphorylation and prolonging STAT1 activation through specific inhibition of T-cell protein tyrosine phosphatase (TCPTP), an important tyrosine phosphatase for STAT1 dephosphorylation. More interestingly, wedelolactone inhibited TCPTP through interaction with the C-terminal autoinhibition domain of TCPTP. We also found that wedelolactone synergized with IFN-γ to induce apoptosis of tumor cells. Our data suggest a new target for anticancer or antiproliferation drugs, a new mechanism to regulate PTPs specifically, and a new drug candidate for treating cancer or other proliferation disorders.
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Affiliation(s)
- Zhimin Chen
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Xiaoxiao Sun
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Shensi Shen
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Haohao Zhang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Xiuquan Ma
- Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Jingli Liu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Shan Kuang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China
| | - Qiang Yu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203 Shanghai, China.
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Li L, Wang Q, Yang Y, Wu G, Xin X, Aisa HA. Chemical components and antidiabetic activity of essential oils obtained by hydrodistillation and three solvent extraction methods fromCarthamus tinctoriusL. ACTA CHROMATOGR 2012. [DOI: 10.1556/achrom.24.2012.4.11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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10
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The tyrosine phosphatase TC48 interacts with and inactivates the oncogenic fusion protein BCR-Abl but not cellular Abl. Biochim Biophys Acta Mol Basis Dis 2012; 1832:275-84. [PMID: 23124138 DOI: 10.1016/j.bbadis.2012.10.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 10/25/2012] [Accepted: 10/26/2012] [Indexed: 11/20/2022]
Abstract
The chimeric oncoprotein BCR-Abl exhibits deregulated protein tyrosine kinase activity and is responsible for the pathogenesis of certain human leukemias, such as chronic myelogenous leukemia. The activities of cellular Abl (c-Abl) and BCR-Abl are stringently regulated and the cellular mechanisms involved in their inactivation are poorly understood. Protein tyrosine phosphatases can negatively regulate Abl mediated signaling by dephosphorylating the kinase and/or its substrates. This study investigated the ability of the intracellular T cell protein tyrosine phosphatase (TCPTP/PTPN2) to dephosphorylate and regulate the functions of BCR-Abl and c-Abl. TCPTP is expressed as two alternately spliced isoforms - TC48 and TC45, which differ in their C-termini and localize to the cytoplasm and nucleus respectively. We show that TC48 dephosphorylates BCR-Abl but not c-Abl and inhibits its activity towards its substrate, CrkII. Y1127 and Y1294 residues whose phosphorylation corresponds with BCR-Abl activation status were the primary sites targeted by TC48. Co-localization and immunoprecipitation experiments showed that TC48 interacted with BCR-Abl but not with c-Abl, and BCR domain was sufficient for interaction. TC48 expression resulted in the stabilization of Bcr-Abl protein dependent on its phosphatase activity. Inactivation of cellular TC48 in K562 cells by stable expression of a dominant negative catalytically inactive mutant TC48, enhanced proliferation. TC48 expressing K562 clones showed reduced proliferation and enhanced sensitivity to STI571 compared to control clones suggesting that TC48 can repress the growth of CML cells. This study identifies a novel cellular regulator that specifically inhibits the activity of oncogenic BCR-Abl but not that of the cellular Abl kinase.
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Doody KM, Bourdeau A, Tremblay ML. T-cell protein tyrosine phosphatase is a key regulator in immune cell signaling: lessons from the knockout mouse model and implications in human disease. Immunol Rev 2009; 228:325-41. [PMID: 19290937 DOI: 10.1111/j.1600-065x.2008.00743.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The immune system requires for its proper ontogeny, differentiation, and maintenance the function of several tyrosine kinases and adapters that create and modify tyrosine phosphorylation sites. Tyrosine phosphorylation is a crucial protein modification in immune cell signaling and can be reversed by protein tyrosine phosphatases (PTPs). Much progress has been made in identifying and understanding PTP function in the immune system. In this review, we present one of these proteins, named T-cell PTPs (TC-PTP) (gene name PTPN2), a classical, non-receptor PTP that is ubiquitously expressed with particularly high expression in hematopoietic tissues. TC-PTP is remarkable not only by the fact that it appears to influence most, if not all, cells involved in the development of the immune system, from stem cells to differentiated lineages, but also recent findings have positioned it at the core of several human diseases from autoimmune disease to cancer.
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Affiliation(s)
- Karen M Doody
- Department of Biochemistry, McGill University, Montreal, QC, Canada
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2-Aryl-3,3,3-trifluoro-2-hydroxypropionic acids: A new class of protein tyrosine phosphatase 1B inhibitors. Bioorg Med Chem Lett 2007; 17:6579-83. [DOI: 10.1016/j.bmcl.2007.09.069] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 09/19/2007] [Accepted: 09/20/2007] [Indexed: 11/23/2022]
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13
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Marlo JE, Desai CJ. Loss of phosphatase activity in Ptp69D alleles supporting axon guidance defects. J Cell Biochem 2006; 98:1296-307. [PMID: 16514605 DOI: 10.1002/jcb.20862] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PTP69D is a receptor protein tyrosine phosphatase that was identified as a key regulator of neuromuscular axon guidance in Drosophila, and has subsequently been shown to play a similar role in the central nervous system and retina. Three Ptp69D alleles with mutations involving catalytically important residues exhibit a high degree of phenotypic variation with viability of mutant adult flies ranging from 0 to 96%, and ISNb motor nerve defects ranging from 11 to 57% [Desai and Purdy, 2003]. To determine whether mutations in Ptp69D affecting axon guidance and viability demonstrate losses of phosphatase activity and whether differences in catalytic potential underlie phenotypic variability, we expressed full-length wild-type and mutant PTP69D protein in Schneider 2 cells, and assessed phosphatase activity using the fluorogenic substrate 6,8-difluoro-4-methylumbelliferone phosphate (DiFMUP). Detailed biochemical characterization of wild-type PTP69D, including an examination of sensitivity to various inhibitors, in vitro catalytic efficiency, and the pH-k(cat) profile of the enzyme, suggests a common tyrosine phosphatase reaction mechanism despite lack of sequence conservation in the WPD loop. Analysis of mutant proteins revealed that every mutant had less than 1% activity relative to the wild-type enzyme, and these rates did not differ significantly from one another. These results indicate that mutations in Ptp69D resulting in axon guidance defects and lethality significantly compromise catalytic activity, yet the range of biological activity exhibited by Ptp69D mutants cannot be explained by differences in catalytic activity, as gauged by their ability to hydrolyze the substrate DiFMUP.
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Affiliation(s)
- Joy E Marlo
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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14
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Worby CA, Gentry MS, Dixon JE. Laforin, a dual specificity phosphatase that dephosphorylates complex carbohydrates. J Biol Chem 2006; 281:30412-8. [PMID: 16901901 PMCID: PMC2774450 DOI: 10.1074/jbc.m606117200] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Laforin is the only phosphatase in the animal kingdom that contains a carbohydrate-binding module. Mutations in the gene encoding laforin result in Lafora disease, a fatal autosomal recessive neurodegenerative disorder, which is diagnosed by the presence of intracellular deposits of insoluble complex carbohydrates known as Lafora bodies. We demonstrate that laforin interacts with proteins known to be involved in glycogen metabolism and rule out several of these proteins as potential substrates. Surprisingly, we find that laforin displays robust phosphatase activity against a phosphorylated complex carbohydrate. Furthermore, this activity is unique to laforin, since several other phosphatases are unable to dephosphorylate polysaccharides. Finally, fusing the carbohydrate-binding module of laforin to the dual specific phosphatase VHR does not result in the ability of this phosphatase to dephosphorylate polysaccharides. Therefore, we hypothesize that laforin is unique in its ability to utilize a phosphorylated complex carbohydrate as a substrate and that this function may be necessary for the maintenance of normal cellular glycogen.
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Affiliation(s)
- Carolyn A Worby
- Department of Pharmacology, University of California at San Diego, La Jolla, California 92093-0721, USA
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15
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Asante-Appiah E, Patel S, Desponts C, Taylor JM, Lau C, Dufresne C, Therien M, Friesen R, Becker JW, Leblanc Y, Kennedy BP, Scapin G. Conformation-assisted Inhibition of Protein-tyrosine Phosphatase-1B Elicits Inhibitor Selectivity over T-cell Protein-tyrosine Phosphatase. J Biol Chem 2006; 281:8010-5. [PMID: 16407290 DOI: 10.1074/jbc.m511827200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PTP-1B represents an attractive target for the treatment of type 2 diabetes and obesity. Given the role that protein phosphatases play in the regulation of many biologically relevant processes, inhibitors against PTP-1B must be not only potent, but also selective. It has been extremely difficult to synthesize inhibitors that are selective over the highly homologous TCPTP. We have successfully exploited the conservative Leu119 to Val substitution between the two enzymes to synthesize a PTP-1B inhibitor that is an order of magnitude more selective over TCPTP. Structural analyses of PTP-1B/inhibitor complexes show a conformation-assisted inhibition mechanism as the basis for selectivity. Such an inhibitory mechanism may be applicable to other homologous enzymes.
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Affiliation(s)
- Ernest Asante-Appiah
- Department of Biochemistry and Molecular Biology, Merck Frosst Center for Therapeutic Research, Pointe-Claire, Dorval, Quebec H9R 4P8, Canada.
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16
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Torres E, Rosen MK. Protein-tyrosine Kinase and GTPase Signals Cooperate to Phosphorylate and Activate Wiskott-Aldrich Syndrome Protein (WASP)/Neuronal WASP. J Biol Chem 2006; 281:3513-20. [PMID: 16293614 DOI: 10.1074/jbc.m509416200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein-tyrosine kinases and Rho GTPases regulate many cellular processes, including the reorganization and dynamics of the actin cytoskeleton. The Wiskott-Aldrich syndrome protein (WASP) and its homolog neuronal WASP (N-WASP) are effectors of the Rho GTPase Cdc42 and provide a direct link between activated membrane receptors and the actin cytoskeleton. WASP and N-WASP are also regulated by a large number of other activators, including protein-tyrosine kinases, phosphoinositides, and Src homology 3-containing adaptor proteins, and can therefore serve as signal integrators inside cells. Here we show that Cdc42 and the Src family kinase Lck cooperate at two levels to enhance WASP activation. First, autoinhibition in N-WASP decreases the efficiency (kcat/Km) of phosphorylation and dephosphorylation of the GTPase binding domain by 30- and 40-fold, respectively, and this effect is largely reversed by Cdc42. Second, Cdc42 and the Src homology 3-Src homology 2 module of Lck cooperatively stimulate the activity of phosphorylated WASP, with coupling energy of approximately 2.4 kcal/mol between the two activators. These combined effects provide mechanisms for high specificity in WASP activation by coincident GTPase and kinase signals.
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Affiliation(s)
- Eduardo Torres
- Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Nichols AJ, Mashal RD, Balkan B. Toward the discovery of small molecule PTP1B inhibitors for the treatment of metabolic diseases. Drug Dev Res 2006. [DOI: 10.1002/ddr.20122] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Lu X, Nechushtan H, Ding F, Rosado MF, Singal R, Alizadeh AA, Lossos IS. Distinct IL-4-induced gene expression, proliferation, and intracellular signaling in germinal center B-cell-like and activated B-cell-like diffuse large-cell lymphomas. Blood 2004; 105:2924-32. [PMID: 15591113 DOI: 10.1182/blood-2004-10-3820] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diffuse large B-cell lymphomas (DLBCLs) can be subclassified into germinal center B-cell (GCB)-like and activated B-cell (ABC)-like tumors characterized by long and short survival, respectively. In contrast to ABC-like DLBCL, GCB-like tumors exhibit high expression of components of the interleukin 4 (IL-4) signaling pathway and of IL-4 target genes such as BCL6 and HGAL, whose high expression independently predicts better survival. These observations suggest distinct activity of the IL-4 signaling pathway in DLBCL subtypes. Herein, we demonstrate similar IL-4 expression but qualitatively different IL-4 effects on GCB-like and ABC-like DLBCL. In GCB-like DLBCL, IL-4 induces expression of its target genes, activates signal transducers and activators of transcription 6 (STAT6) signaling, and increases cell proliferation. In contrast, in the ABC-like DLBCL, IL-4 activates AKT, decreases cell proliferation by cell cycle arrest, and does not induce gene expression due to aberrant Janus kinase (JAK)-STAT6 signaling attributed to STAT6 dephosphorylation. We found distinct expression profiles of tyrosine phosphatases in DLBCL subtypes and identified putative STAT6 tyrosine phosphatases-protein tyrosine phosphatase nonreceptor type 1 (PTPN1) and PTPN2, whose expression is significantly higher in ABC-like DLBCL. These differences in tyrosine phosphatase expression might underlie distinct expression profiles of some of the IL-4 target genes and could contribute to a different clinical outcome of patients with GCB-like and ABC-like DLBCLs.
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MESH Headings
- Active Transport, Cell Nucleus
- B-Lymphocytes/pathology
- B-Lymphocytes/physiology
- Cell Division/immunology
- Cell Nucleus/metabolism
- Cell Nucleus/pathology
- Gene Expression Regulation, Neoplastic
- Germinal Center/pathology
- Humans
- Interleukin-4/genetics
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/pathology
- Lymphoma, B-Cell/physiopathology
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/pathology
- Lymphoma, Large B-Cell, Diffuse/physiopathology
- Oligonucleotide Array Sequence Analysis
- Phosphorylation
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatases/metabolism
- STAT6 Transcription Factor
- Signal Transduction/immunology
- Trans-Activators/metabolism
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Affiliation(s)
- Xiaoqing Lu
- Sylvester Comprehensive Cancer Center, Division of Hematology-Oncology, Department of Medicine, University of Miami, 1475 NW 12th Ave (D8-4), Miami, FL 33136, USA
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19
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Shiraishi I, Melendez J, Ahn Y, Skavdahl M, Murphy E, Welch S, Schaefer E, Walsh K, Rosenzweig A, Torella D, Nurzynska D, Kajstura J, Leri A, Anversa P, Sussman MA. Nuclear targeting of Akt enhances kinase activity and survival of cardiomyocytes. Circ Res 2004; 94:884-91. [PMID: 14988230 DOI: 10.1161/01.res.0000124394.01180.be] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Heart failure is associated with death of cardiomyocytes leading to loss of contractility. Previous studies using membrane-targeted Akt (myristolated-Akt), an enzyme involved in antiapoptotic signaling, showed inhibition of cell death and prevention of pathogenesis induced by cardiomyopathic stimuli. However, recent studies by our group have found accumulation of activated Akt in the nucleus, suggesting that biologically relevant target(s) of Akt activity may be located there. To test this hypothesis, a targeted Akt construct was created to determine the antiapoptotic action of nuclear Akt accumulation. Nuclear localization of the adenovirally encoded Akt construct was confirmed by confocal microscopy. Cardiomyocytes expressing nuclear-targeted Akt showed no evidence of morphological remodeling such as altered myofibril density or hypertrophy. Nuclear-targeted Akt significantly elevated levels of phospho-Akt and kinase activity and inhibited apoptosis as effectively as myristolated-Akt in hypoxia-induced cell death. Transgenic overexpression of nuclear-targeted Akt did not result in hypertrophic remodeling, altered cardiomyocyte DNA content or nucleation, or enhanced phosphorylation of typical cytoplasmic Akt substrates, yet transgenic hearts were protected from ischemia-reperfusion injury. Gene array analyses demonstrated changes in the transcriptional profile of Akt/nuc hearts compared with nontransgenic controls distinct from prior characterizations of Akt expression in transgenic hearts. Collectively, these experiments show that targeting of Akt to the nucleus mediates inhibition of apoptosis without hypertrophic remodeling, opening new possibilities for therapeutic applications of nuclear-targeted Akt to inhibit cell death associated with heart disease.
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Affiliation(s)
- Isao Shiraishi
- The Children's Hospital Research Foundation, Division of Molecular Cardiovascular Biology; Cincinnati, Ohio, USA
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Romsicki Y, Reece M, Gauthier JY, Asante-Appiah E, Kennedy BP. Protein tyrosine phosphatase-1B dephosphorylation of the insulin receptor occurs in a perinuclear endosome compartment in human embryonic kidney 293 cells. J Biol Chem 2004; 279:12868-75. [PMID: 14722096 DOI: 10.1074/jbc.m309600200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein tyrosine phosphatase-1B (PTP-1B) is a negative regulator of insulin signaling. It is thought to carry out this role by interacting with and dephosphorylating the activated insulin receptor (IR). However, little is known regarding the nature of the cellular interaction between these proteins, especially because the IR is localized to the plasma membrane and PTP-1B to the endoplasmic reticulum. Using confocal microscopy and fluorescence resonance energy transfer (FRET), the interaction between PTP-1B and the IR was examined in co-transfected human embryonic kidney 293 cells. Biological activities were not significantly affected for either PTP-1B or the IR with the fusion of W1B-green fluorescent protein (GFP) to the N terminus of PTP-1B (W1B-PTP-1B) or the fusion of Topaz-GFP to the C terminus of the IR (Topaz-IR). FRET between W1B and Topaz was monitored in cells transfected with either wild type PTP-1B (W1B-PTP-1B) or the substrate-trapping form PTP-1B(D181A) (W1B-PTP-1B(D181A)) and Topaz-IR. Co-expression of W1B-PTP-1B with Topaz-IR resulted in distribution of Topaz-IR to the plasma membrane, but no FRET was obtained upon insulin treatment. In contrast, co-expression of W1B-PTP-1B(D181A) with Topaz-IR caused an increase in cytosolic Topaz-IR fluorescence and, in some cells, a significant basal FRET signal, suggesting that PTP-1B is interacting with the IR during its synthesis. Stimulation of these cells with insulin resulted in a rapid induction of FRET that increased over time and was localized to a perinuclear spot. Co-expression of Topaz-IR with a GFP-labeled RhoB endosomal marker and treatment of the cells with insulin identified a perinuclear endosome compartment as the site of localization. Furthermore, the insulin-induced FRET could be prevented by the treatment of the cells with a specific PTP-1B inhibitor. These results suggest that PTP-1B appears not only to interact with and dephosphorylate the insulin-stimulated IR in a perinuclear endosome compartment but is also involved in maintaining the IR in a dephosphorylated state during its biosynthesis.
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MESH Headings
- Blotting, Western
- Cell Line
- Cell Membrane/metabolism
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Endoplasmic Reticulum/metabolism
- Endosomes/metabolism
- Enzyme Inhibitors/pharmacology
- Fluorescence Resonance Energy Transfer
- Genetic Vectors
- Green Fluorescent Proteins
- Humans
- Image Processing, Computer-Assisted
- Insulin/metabolism
- Kinetics
- Luminescent Proteins/metabolism
- Microscopy, Confocal
- Microscopy, Fluorescence
- Models, Chemical
- Phosphorylation
- Precipitin Tests
- Protein Binding
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/metabolism
- Receptor, Insulin/chemistry
- Receptor, Insulin/metabolism
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
- Transfection
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Affiliation(s)
- Yolanda Romsicki
- Department of Biochemistry & Molecular Biology, Merck Frosst Centre for Therapeutic Research, Pointe-Claire-Dorval, Quebec H9R 4P8, Canada
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