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Yang MH, Jung SH, Chinnathambi A, Alahmadi TA, Alharbi SA, Sethi G, Ahn KS. Attenuation of STAT3 Signaling Cascade by Daidzin Can Enhance the Apoptotic Potential of Bortezomib against Multiple Myeloma. Biomolecules 2019; 10:biom10010023. [PMID: 31878046 PMCID: PMC7022648 DOI: 10.3390/biom10010023] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/19/2019] [Accepted: 12/19/2019] [Indexed: 12/21/2022] Open
Abstract
Daidzin (DDZ) extracted from Pueraria lobate (Fabaceae) is a widely known phytoestrogen. DDZ can display anti-cancer activities against breast and prostate cancers, but its anti-oncogenic actions in multiple myeloma (MM) cells have not been studied. The signal transducer and activator of transcription 3 (STAT3) can control key processes including proliferation, differentiation, and survival in MM cells. Here, we noted that DDZ abrogated STAT3 activation (both constitutive as well as inducible) at Tyr705 and Ser727 in MM cells. Additionally, DDZ mitigated the phosphorylation of STAT3 upstream Janus-activated kinases (JAK1/2) and c-Src kinases. Pervanadate (tyrosine phosphatase blocker) exposure altered the DDZ-induced inhibition of STAT3 activation, thus affecting the action of this phytoestrogen on apoptosis. Moreover, DDZ impeded proliferation and augmented the apoptotic effects of bortezomib (Bor) in MM cells. Overall, the data indicate that DDZ may act as a potent suppressor of STAT3 signaling cascade, and the co-treatment of DDZ and Bor could be a promising therapeutic strategy, specifically in MM.
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Affiliation(s)
- Min Hee Yang
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul 02447, Korea; (M.H.Y.); (S.H.J.)
- Department of Science in Korean Medicine, Kyung Hee University, 24 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Korea
| | - Sang Hoon Jung
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul 02447, Korea; (M.H.Y.); (S.H.J.)
| | - Arunachalam Chinnathambi
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.C.); (S.A.A.)
| | - Tahani Awad Alahmadi
- Department of Pediatrics, College of Medicine and King Khalid University Hospital, King Saud University Medical City, Riyadh 11461, Saudi Arabia;
| | - Sulaiman Ali Alharbi
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.C.); (S.A.A.)
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117600, Singapore
- Correspondence: (G.S.); (K.S.A.)
| | - Kwang Seok Ahn
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul 02447, Korea; (M.H.Y.); (S.H.J.)
- Department of Science in Korean Medicine, Kyung Hee University, 24 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Korea
- Correspondence: (G.S.); (K.S.A.)
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Lapointe F, Turcotte S, Véronneau S, Rola-Pleszczynski M, Stankova J. Role of Protein Tyrosine Phosphatase Epsilon (PTP ε) in Leukotriene D 4-Induced CXCL8 Expression. J Pharmacol Exp Ther 2019; 369:270-281. [PMID: 30867226 DOI: 10.1124/jpet.118.255422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/06/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphorylation on tyrosine residues is recognized as an important mechanism for connecting extracellular stimuli to cellular events and defines a variety of physiologic responses downstream of G protein-coupled receptor (GPCR) activation. To date, few protein tyrosine phosphatases (PTPs) have been shown to associate with GPCRs, and little is known about their role in GPCR signaling. To discover potential cysteinyl-leukotriene receptor (CysLT1R)-interacting proteins, we identified protein tyrosine phosphatase ε (PTPε) in a yeast two-hybrid assay. Since both proteins are closely linked to asthma, we further investigated their association. Using a human embryonic kidney cell line 293 (HEK-293) cell line stably transfected with the receptor (HEK-LT1), as well as human primary monocytes, we found that PTPε colocalized with CysLT1R in both resting and leukotriene D4 (LTD4)-stimulated cells. Cotransfection of HEK-LT1 with PTPε had no effect on CysLT1R expression or LTD4-induced internalization, but it inhibited LTD4-induced CXC chemokine 8 (CXCL8) promoter transactivation, protein expression, and secretion. Moreover, reduced phosphorylation of extracellular signal regulated kinase 1/2 (ERK1/2), but not of p38 or c-Jun-N-terminal kinase 1 or 2 mitogen-activated protein kinases (MAPKs), was observed upon LTD4 stimulation of HEK-LT1 coexpressing cytosolic (cyt-) PTPε, but not receptor (R) PTPε The increased interaction of cyt-PTPε and ERK1/2 after LTD4 stimulation was shown by coimmunoprecipitation. In addition, enhanced ERK1/2 phosphorylation and CXCL8 secretion were found in LTD4-stimulated human monocytes transfected with PTPε-specific siRNAs, adding support to a regulatory/inhibitory role of PTPε in CysLT1R signaling. Given that the prevalence of severe asthma is increasing, the identification of PTPε as a new potential therapeutic target may be of interest.
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Affiliation(s)
- Fanny Lapointe
- Division of Immunology and Allergy, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Sylvie Turcotte
- Division of Immunology and Allergy, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Steeve Véronneau
- Division of Immunology and Allergy, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Marek Rola-Pleszczynski
- Division of Immunology and Allergy, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jana Stankova
- Division of Immunology and Allergy, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Capsazepine inhibits JAK/STAT3 signaling, tumor growth, and cell survival in prostate cancer. Oncotarget 2017; 8:17700-17711. [PMID: 27458171 PMCID: PMC5392279 DOI: 10.18632/oncotarget.10775] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 07/14/2016] [Indexed: 11/25/2022] Open
Abstract
Persistent STAT3 activation is seen in many tumor cells and promotes malignant transformation. Here, we investigated whether capsazepine (Capz), a synthetic analogue of capsaicin, exerts anticancer effects by inhibiting STAT3 activation in prostate cancer cells. Capz inhibited both constitutive and induced STAT3 activation in human prostate carcinoma cells. Capz also inhibited activation of the upstream kinases JAK1/2 and c-Src. The phosphatase inhibitor pervanadate reversed Capz-induced STAT3 inhibition, indicating that the effect of Capz depends on a protein tyrosine phosphatase. Capz treatment increased PTPε protein and mRNA levels. Moreover, siRNA-mediated knockdown of PTPε reversed the Capz-induced induction of PTPε and inhibition of STAT3 activation, indicating that PTPε is crucial for Capz-dependent STAT3 dephosphorylation. Capz also decreased levels of the protein products of various oncogenes, which in turn inhibited proliferation and invasion and induced apoptosis. Finally, intraperitoneal Capz administration decreased tumor growth in a xenograft mouse prostate cancer model and reduced p-STAT3 and Ki-67 expression. These data suggest that Capz is a novel pharmacological inhibitor of STAT3 activation with several anticancer effects in prostate cancer cells.
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Nunes-Xavier CE, Elson A, Pulido R. Epidermal growth factor receptor (EGFR)-mediated positive feedback of protein-tyrosine phosphatase epsilon (PTPepsilon) on ERK1/2 and AKT protein pathways is required for survival of human breast cancer cells. J Biol Chem 2011; 287:3433-44. [PMID: 22117074 DOI: 10.1074/jbc.m111.293928] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Increased tyrosine phosphorylation has been correlated with human cancer, including breast cancer. In general, the activation of tyrosine kinases (TKs) can be antagonized by the action of protein-tyrosine phosphatases (PTPs). However, in some cases PTPs can potentiate the activation of TKs. In this study, we have investigated the functional role of PTPε in human breast cancer cell lines. We found the up-regulation and activation of receptor PTPε (RPTPε) in MCF-7 cells and MDA-MB-231 upon PMA, FGF, and serum stimulation, which depended on EGFR and ERK1/2 activity. Diminishing the expression of PTPε in human breast cancer cells abolished ERK1/2 and AKT activation, and decreased the viability and anchorage-independent growth of the cells. Conversely, stable MCF-7 cell lines expressing inducible high levels of ectopic PTPε displayed higher activation of ERK1/2 and anchorage-independent growth. Our results demonstrate that expression of PTPε is up-regulated and activated in breast cancer cell lines, through EGFR, by sustained activation of the ERK1/2 pathway, generating a positive feedback regulatory loop required for survival of human breast cancer cells.
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Reinhard J, Horvat-Bröcker A, Illes S, Zaremba A, Knyazev P, Ullrich A, Faissner A. Protein tyrosine phosphatases expression during development of mouse superior colliculus. Exp Brain Res 2009; 199:279-97. [PMID: 19727691 PMCID: PMC2845883 DOI: 10.1007/s00221-009-1963-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 07/22/2009] [Indexed: 01/17/2023]
Abstract
Protein tyrosine phosphatases (PTPs) are key regulators of different processes during development of the central nervous system. However, expression patterns and potential roles of PTPs in the developing superior colliculus remain poorly investigated. In this study, a degenerate primer-based reverse transcription-polymerase chain reaction (RT-PCR) approach was used to isolate seven different intracellular PTPs and nine different receptor-type PTPs (RPTPs) from embryonic E15 mouse superior colliculus. Subsequently, the expression patterns of 11 PTPs (TC-PTP, PTP1C, PTP1D, PTP-MEG2, PTP-PEST, RPTPJ, RPTPε, RPTPRR, RPTPσ, RPTPκ and RPTPγ) were further analyzed in detail in superior colliculus from embryonic E13 to postnatal P20 stages by quantitative real-time RT-PCR, Western blotting and immunohistochemistry. Each of the 11 PTPs exhibits distinct spatiotemporal regulation of mRNAs and proteins in the developing superior colliculus suggesting their versatile roles in genesis of neuronal and glial cells and retinocollicular topographic mapping. At E13, additional double-immunohistochemical analysis revealed the expression of PTPs in collicular nestin-positive neural progenitor cells and RC-2-immunoreactive radial glia cells, indicating the potential functional importance of PTPs in neurogenesis and gliogenesis.
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Affiliation(s)
- Jacqueline Reinhard
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology, Ruhr-University Bochum, Universitaetsstr 150, 44780 Bochum, Germany
| | - Andrea Horvat-Bröcker
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology, Ruhr-University Bochum, Universitaetsstr 150, 44780 Bochum, Germany
| | - Sebastian Illes
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology, Ruhr-University Bochum, Universitaetsstr 150, 44780 Bochum, Germany
- Department of Neurology, Heinrich-Heine University, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Angelika Zaremba
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology, Ruhr-University Bochum, Universitaetsstr 150, 44780 Bochum, Germany
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, PO Box 12233, Durham, NC 27709 USA
| | - Piotr Knyazev
- Department of Molecular Biology, Max-Planck-Institute, Martinsried, Germany
| | - Axel Ullrich
- Department of Molecular Biology, Max-Planck-Institute, Martinsried, Germany
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology, Ruhr-University Bochum, Universitaetsstr 150, 44780 Bochum, Germany
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Akimoto M, Mishra K, Lim KT, Tani N, Hisanaga SI, Katagiri T, Elson A, Mizuno K, Yakura H. Protein Tyrosine Phosphatase ε is a Negative Regulator of FcεRI-mediated Mast Cell Responses. Scand J Immunol 2009; 69:401-11. [DOI: 10.1111/j.1365-3083.2009.02235.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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De Franceschi L, Biondani A, Carta F, Turrini F, Laudanna C, Deana R, Brunati AM, Turretta L, Iolascon A, Perrotta S, Elson A, Bulato C, Brugnara C. PTPepsilon has a critical role in signaling transduction pathways and phosphoprotein network topology in red cells. Proteomics 2008; 8:4695-708. [PMID: 18924107 PMCID: PMC3008556 DOI: 10.1002/pmic.200700596] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Indexed: 12/31/2022]
Abstract
Protein tyrosine phosphatases (PTPs) are crucial components of cellular signal transduction pathways. Here, we report that red blood cells (RBCs) from mice lacking PTPepsilon (Ptpre(-/-)) exhibit (i) abnormal morphology; (ii) increased Ca(2+)-activated-K(+) channel activity, which was partially blocked by the Src family kinases (SFKs) inhibitor PP1; and (iii) market perturbation of the RBC membrane tyrosine (Tyr-) phosphoproteome, indicating an alteration of RBC signal transduction pathways. Using the signaling network computational analysis of the Tyr-phosphoproteomic data, we identified seven topological clusters. We studied cluster 1 containing Fyn, SFK, and Syk another tyrosine kinase. In Ptpre(-/-)mouse RBCs, the activity of Fyn was increased while Syk kinase activity was decreased compared to wild-type RBCs, validating the network computational analysis, and indicating a novel signaling pathway, which involves Fyn and Syk in regulation of red cell morphology.
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Affiliation(s)
- Lucia De Franceschi
- Department of Clinical and Experimental Medicine, Section of Internal Medicine, University of Verona, Verona, Italy.
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Berman-Golan D, Granot-Attas S, Elson A. Protein tyrosine phosphatase epsilon and Neu-induced mammary tumorigenesis. Cancer Metastasis Rev 2008; 27:193-203. [DOI: 10.1007/s10555-008-9124-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Kraut-Cohen J, Muller WJ, Elson A. Protein-tyrosine phosphatase epsilon regulates Shc signaling in a kinase-specific manner: increasing coherence in tyrosine phosphatase signaling. J Biol Chem 2007; 283:4612-21. [PMID: 18093973 DOI: 10.1074/jbc.m708822200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Individual protein tyrosine kinases and phosphatases target multiple substrates; this may generate conflicting signals, possibly within a single pathway. Protein-tyrosine phosphatase epsilon (PTPepsilon) performs two potentially opposing roles: in Neu-induced mammary tumors, PTPepsilon activates Src downstream of Neu, whereas in other systems PTPepsilon can indirectly down-regulate MAP kinase signaling. We now show that the latter effect is mediated at least in part via the adaptor protein Shc. PTPepsilon binds and dephosphorylates Shc in vivo, reducing the association of Shc with Grb2 and inhibiting downstream ERK activation. PTPepsilon binds Shc in a phosphotyrosine-independent manner mediated by the Shc PTB domain and aided by a sequence of 10 N-terminal residues in PTPepsilon. Surprisingly, PTPepsilon dephosphorylates Shc in a kinase-dependent manner; PTPepsilon targets Shc in the presence of Src but not in the presence of Neu. Using a series of point mutants of Shc and Neu, we show that Neu protects Shc from dephosphorylation by binding the PTB domain of Shc, most likely competing against PTPepsilon for binding the same domain. In agreement, PTPepsilon dephosphorylates Shc in mouse embryo fibroblasts but not in Neu-induced mammary tumor cells. We conclude that in the context of Neu-induced mammary tumor cells, Neu prevents PTPepsilon from targeting Shc and from reducing its promitogenic signal while phosphorylating PTPepsilon and directing it to activate Src in support of mitogenesis. In so doing, Neu contributes to the coherence of the promitogenic role of PTPepsilon in this system.
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Affiliation(s)
- Judith Kraut-Cohen
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
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Sines T, Granot-Attas S, Weisman-Welcher S, Elson A. Association of tyrosine phosphatase epsilon with microtubules inhibits phosphatase activity and is regulated by the epidermal growth factor receptor. Mol Cell Biol 2007; 27:7102-12. [PMID: 17709387 PMCID: PMC2168897 DOI: 10.1128/mcb.02096-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Protein tyrosine phosphatases (PTPs) are key mediators that link physiological cues with reversible changes in protein structure and function; nevertheless, significant details concerning their regulation in vivo remain unknown. We demonstrate that PTPepsilon associates with microtubules in vivo and is inhibited by them in a noncompetitive manner. Microtubule-associated proteins, which interact strongly with microtubules in vivo, significantly increase binding of PTPepsilon to tubulin in vitro and further reduce phosphatase activity. Conversely, disruption of microtubule structures in cells reduces their association with PTPepsilon, alters the subcellular localization of the phosphatase, and increases its specific activity. Activation of the epidermal growth factor receptor (EGFR) increases the PTPepsilon-microtubule association in a manner dependent upon EGFR-induced phosphorylation of PTPepsilon at Y638 and upon microtubule integrity. These events are transient and occur with rapid kinetics similar to EGFR autophosphorylation, suggesting that activation of the EGFR transiently down-regulates PTPepsilon activity near the receptor by promoting the PTPepsilon-microtubule association. Tubulin also inhibits the tyrosine phosphatase PTP1B but not receptor-type PTPmu or the unrelated alkaline phosphatase. The data suggest that reversible association with microtubules is a novel, physiologically regulated mechanism for regulation of tyrosine phosphatase activity in cells.
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Affiliation(s)
- Tal Sines
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
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Tiran Z, Peretz A, Sines T, Shinder V, Sap J, Attali B, Elson A. Tyrosine phosphatases epsilon and alpha perform specific and overlapping functions in regulation of voltage-gated potassium channels in Schwann cells. Mol Biol Cell 2006; 17:4330-42. [PMID: 16870705 PMCID: PMC1635364 DOI: 10.1091/mbc.e06-02-0151] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Tyrosine phosphatases (PTPs) epsilon and alpha are closely related and share several molecular functions, such as regulation of Src family kinases and voltage-gated potassium (Kv) channels. Functional interrelationships between PTPepsilon and PTPalpha and the mechanisms by which they regulate K+ channels and Src were analyzed in vivo in mice lacking either or both PTPs. Lack of either PTP increases Kv channel activity and phosphorylation in Schwann cells, indicating these PTPs inhibit Kv current amplitude in vivo. Open probability and unitary conductance of Kv channels are unchanged, suggesting an effect on channel number or organization. PTPalpha inhibits Kv channels more strongly than PTPepsilon; this correlates with constitutive association of PTPalpha with Kv2.1, driven by membranal localization of PTPalpha. PTPalpha, but not PTPepsilon, activates Src in sciatic nerve extracts, suggesting Src deregulation is not responsible exclusively for the observed phenotypes and highlighting an unexpected difference between both PTPs. Developmentally, sciatic nerve myelination is reduced transiently in mice lacking either PTP and more so in mice lacking both PTPs, suggesting both PTPs support myelination but are not fully redundant. We conclude that PTPepsilon and PTPalpha differ significantly in their regulation of Kv channels and Src in the system examined and that similarity between PTPs does not necessarily result in full functional redundancy in vivo.
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Affiliation(s)
| | - Asher Peretz
- Department of Physiology and Pharmacology, Tel Aviv University Medical School, Tel Aviv 69978, Israel; and
| | - Tal Sines
- Departments of *Molecular Genetics and
| | - Vera Shinder
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jan Sap
- Department of Pharmacology, New York University Medical School, New York, NY 10016
| | - Bernard Attali
- Department of Physiology and Pharmacology, Tel Aviv University Medical School, Tel Aviv 69978, Israel; and
| | - Ari Elson
- Departments of *Molecular Genetics and
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McCormack E, Bruserud O, Gjertsen BT. Animal models of acute myelogenous leukaemia - development, application and future perspectives. Leukemia 2005; 19:687-706. [PMID: 15759039 DOI: 10.1038/sj.leu.2403670] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
From the early inception of the transplant models through to contemporary genetic and xenograft models, evolution of murine leukaemic model systems have been critical to our general comprehension and treatment of cancer, and, more specifically, disease states such as acute myelogenous leukaemia (AML). However, even with modern advances in therapeutics and molecular diagnostics, the majority of AML patients die from their disease. Thus, in the absence of definitive in vitro models which precisely recapitulate the in vivo setting of human AMLs and failure of significant numbers of new drugs late in clinical trials, it is essential that murine AML models are developed to exploit more specific, targeted therapeutics. While various model systems are described and discussed in the literature from initial transplant models such as BNML and spontaneous murine leukaemia virus models, to the more definitive genetic and clinically significant NOD/SCID xenograft models, there exists no single compendium which directly assesses, reviews or compares the relevance of these models. Thus, the function of this article is to provide clinicians and experimentalists a chronological, comprehensive appraisal of all AML model systems, critical discussion on the elucidation of their roles in our understanding of AML and consideration to their efficacy in the development of AML chemotherapeutics.
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Affiliation(s)
- E McCormack
- Hematology Section, Institute of Medicine, University of Bergen, Bergen, Norway
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Chiusaroli R, Knobler H, Luxenburg C, Sanjay A, Granot-Attas S, Tiran Z, Miyazaki T, Harmelin A, Baron R, Elson A. Tyrosine phosphatase epsilon is a positive regulator of osteoclast function in vitro and in vivo. Mol Biol Cell 2003; 15:234-44. [PMID: 14528021 PMCID: PMC307543 DOI: 10.1091/mbc.e03-04-0207] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Protein tyrosine phosphorylation is a major regulator of bone metabolism. Tyrosine phosphatases participate in regulating phosphorylation, but roles of specific phosphatases in bone metabolism are largely unknown. We demonstrate that young (<12 weeks) female mice lacking tyrosine phosphatase epsilon (PTPepsilon) exhibit increased trabecular bone mass due to cell-specific defects in osteoclast function. These defects are manifested in vivo as reduced association of osteoclasts with bone and as reduced serum concentration of C-terminal collagen telopeptides, specific products of osteoclast-mediated bone degradation. Osteoclast-like cells are generated readily from PTPepsilon-deficient bone-marrow precursors. However, cultures of these cells contain few mature, polarized cells and perform poorly in bone resorption assays in vitro. Podosomes, structures by which osteoclasts adhere to matrix, are disorganized and tend to form large clusters in these cells, suggesting that lack of PTPepsilon adversely affects podosomal arrangement in the final stages of osteoclast polarization. The gender and age specificities of the bone phenotype suggest that it is modulated by hormonal status, despite normal serum levels of estrogen and progesterone in affected mice. Stimulation of bone resorption by RANKL and, surprisingly, Src activity and Pyk2 phosphorylation are normal in PTPepsilon-deficient osteoclasts, indicating that loss of PTPepsilon does not cause widespread disruption of these signaling pathways. These results establish PTPepsilon as a phosphatase required for optimal structure, subcellular organization, and function of osteoclasts in vivo and in vitro.
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Affiliation(s)
- Riccardo Chiusaroli
- Departments of Cell Biology and Orthopedics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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