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Gao J, Wei B, de Assuncao TM, Liu Z, Hu X, Ibrahim S, Cooper SA, Cao S, Shah VH, Kostallari E. Hepatic stellate cell autophagy inhibits extracellular vesicle release to attenuate liver fibrosis. J Hepatol 2020; 73:1144-1154. [PMID: 32389810 PMCID: PMC7572579 DOI: 10.1016/j.jhep.2020.04.044] [Citation(s) in RCA: 158] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Autophagy plays a crucial role in hepatic homeostasis and its deregulation has been associated with chronic liver disease. However, the effect of autophagy on the release of fibrogenic extracellular vesicles (EVs) by platelet-derived growth factor (PDGF)-stimulated hepatic stellate cells (HSCs) remains unknown. Herein, we aimed to elucidate the role of autophagy, specifically relating to fibrogenic EV release, in fibrosis. METHODS In vitro experiments were conducted in primary human and murine HSCs as well as LX2 cells. Small EVs were purified by differential ultracentrifugation. Carbon tetrachloride (CCl4) or bile duct ligation (BDL) were used to induce fibrosis in our mouse model. Liver lysates from patients with cirrhosis or healthy controls were compared by RNA sequencing. RESULTS In vitro, PDGF and its downstream molecule SHP2 (Src homology 2-containing protein tyrosine phosphatase 2) inhibited autophagy and increased HSC-derived EV release. We used this PDGF/SHP2 model to further investigate how autophagy affects fibrogenic EV release. RNA sequencing identified an mTOR (mammalian target of rapamycin) signaling molecule that was regulated by SHP2 and PDGF. Disruption of mTOR signaling abolished PDGF-dependent EV release. Activation of mTOR signaling induced the release of multivesicular body-derived exosomes (by inhibiting autophagy) and microvesicles (by activating ROCK1 signaling). These mTOR-dependent EVs promoted in vitro HSC migration. To assess the importance of this mechanism in vivo, SHP2 was selectively deleted in HSCs, which attenuated CCl4- or BDL-induced liver fibrosis. Furthermore, in the CCl4 model, mice receiving circulating EVs derived from mice with HSC-specific Shp2 deletion had less fibrosis than mice receiving EVs from control mice. Correspondingly, SHP2 was upregulated in patients with liver cirrhosis. CONCLUSION These results demonstrate that autophagy in HSCs attenuates liver fibrosis by inhibiting the release of fibrogenic EVs. LAY SUMMARY During liver fibrosis and cirrhosis, activated hepatic stellate cells (HSCs) are the key cell type responsible for fibrotic tissue deposition. Recently, we demonstrated that activated HSCs release nano-sized vesicles enriched with fibrogenic proteins. In the current study, we unveil the mechanism by which these fibrogenic vesicles are released, moving a step closer to the long-term goal of therapeutically targeting this process.
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Affiliation(s)
- Jinhang Gao
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN,Gastroenterology and Hepatology, West China Hospital, Sichuan University, Chengdu, 610041 China
| | - Bo Wei
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN,Gastroenterology and Hepatology, West China Hospital, Sichuan University, Chengdu, 610041 China
| | | | - Zhikui Liu
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Xiao Hu
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Samar Ibrahim
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Shawna A. Cooper
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN,Biochemistry and Molecular Biology Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN
| | - Sheng Cao
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Vijay H. Shah
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Enis Kostallari
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, United States.
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Duchatel RJ, Jackson ER, Alvaro F, Nixon B, Hondermarck H, Dun MD. Signal Transduction in Diffuse Intrinsic Pontine Glioma. Proteomics 2019; 19:e1800479. [DOI: 10.1002/pmic.201800479] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 05/03/2019] [Indexed: 11/12/2022]
Affiliation(s)
- Ryan J. Duchatel
- Cancer Signalling Research Group School of Biomedical Sciences and Pharmacy Faculty of Health and Medicine University of Newcastle Callaghan NSW 2308 Australia
- Priority Research Centre for Cancer Research Innovation and Translation Hunter Medical Research Institute Lambton NSW 2305 Australia
| | - Evangeline R. Jackson
- Cancer Signalling Research Group School of Biomedical Sciences and Pharmacy Faculty of Health and Medicine University of Newcastle Callaghan NSW 2308 Australia
- Priority Research Centre for Cancer Research Innovation and Translation Hunter Medical Research Institute Lambton NSW 2305 Australia
| | - Frank Alvaro
- Priority Research Centre for Cancer Research Innovation and Translation Hunter Medical Research Institute Lambton NSW 2305 Australia
- John Hunter Children's Hospital Faculty of Health and Medicine University of Newcastle New Lambton Heights NSW 2305 Australia
| | - Brett Nixon
- Priority Research Centre for Reproductive Science School of Environmental and Life Sciences University of Newcastle Callaghan NSW 2308 Australia
| | - Hubert Hondermarck
- Priority Research Centre for Cancer Research Innovation and Translation Hunter Medical Research Institute Lambton NSW 2305 Australia
- Cancer Neurobiology Group School of Biomedical Sciences and Pharmacy Faculty of Health and Medicine University of Newcastle Callaghan NSW 2308 Australia
| | - Matthew D. Dun
- Cancer Signalling Research Group School of Biomedical Sciences and Pharmacy Faculty of Health and Medicine University of Newcastle Callaghan NSW 2308 Australia
- Priority Research Centre for Cancer Research Innovation and Translation Hunter Medical Research Institute Lambton NSW 2305 Australia
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3
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Kostallari E, Hirsova P, Prasnicka A, Verma VK, Yaqoob U, Wongjarupong N, Roberts LR, Shah VH. Hepatic stellate cell-derived platelet-derived growth factor receptor-alpha-enriched extracellular vesicles promote liver fibrosis in mice through SHP2. Hepatology 2018; 68:333-348. [PMID: 29360139 PMCID: PMC6033667 DOI: 10.1002/hep.29803] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 01/17/2018] [Accepted: 01/18/2018] [Indexed: 12/11/2022]
Abstract
UNLABELLED Liver fibrosis is characterized by the activation and migration of hepatic stellate cells (HSCs), followed by matrix deposition. Recently, several studies have shown the importance of extracellular vesicles (EVs) derived from liver cells, such as hepatocytes and endothelial cells, in liver pathobiology. While most of the studies describe how liver cells modulate HSC behavior, an important gap exists in the understanding of HSC-derived signals and more specifically HSC-derived EVs in liver fibrosis. Here, we investigated the molecules released through HSC-derived EVs, the mechanism of their release, and the role of these EVs in fibrosis. Mass spectrometric analysis showed that platelet-derived growth factor (PDGF) receptor-alpha (PDGFRα) was enriched in EVs derived from PDGF-BB-treated HSCs. Moreover, patients with liver fibrosis had increased PDGFRα levels in serum EVs compared to healthy individuals. Mechanistically, in vitro tyrosine720-to-phenylalanine mutation on the PDGFRα sequence abolished enrichment of PDGFRα in EVs and redirected the receptor toward degradation. Congruently, the inhibition of Src homology 2 domain tyrosine phosphatase 2, the regulatory binding partner of phosphorylated tyrosine720, also inhibited PDGFRα enrichment in EVs. EVs derived from PDGFRα-overexpressing cells promoted in vitro HSC migration and in vivo liver fibrosis. Finally, administration of Src homology 2 domain tyrosine phosphatase 2inhibitor, SHP099, to carbon tetrachloride-administered mice inhibited PDGFRα enrichment in serum EVs and reduced liver fibrosis. CONCLUSION PDGFRα is enriched in EVs derived from PDGF-BB-treated HSCs in an Src homology 2 domain tyrosine phosphatase 2-dependent manner and these PDGFRα-enriched EVs participate in development of liver fibrosis. (Hepatology 2018;68:333-348).
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Affiliation(s)
- Enis Kostallari
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Petra Hirsova
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Alena Prasnicka
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN,Department of Pharmacology, Charles University, Hradec Kralove, Czech Republic
| | - Vikas K. Verma
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Usman Yaqoob
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | | | - Lewis R. Roberts
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Vijay H. Shah
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
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A Probabilistic Boolean Network Approach for the Analysis of Cancer-Specific Signalling: A Case Study of Deregulated PDGF Signalling in GIST. PLoS One 2016; 11:e0156223. [PMID: 27232499 PMCID: PMC4883749 DOI: 10.1371/journal.pone.0156223] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/11/2016] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Signal transduction networks are increasingly studied with mathematical modelling approaches while each of them is suited for a particular problem. For the contextualisation and analysis of signalling networks with steady-state protein data, we identified probabilistic Boolean network (PBN) as a promising framework which could capture quantitative changes of molecular changes at steady-state with a minimal parameterisation. RESULTS AND CONCLUSION In our case study, we successfully applied the PBN approach to model and analyse the deregulated Platelet-Derived Growth Factor (PDGF) signalling pathway in Gastrointestinal Stromal Tumour (GIST). We experimentally determined a rich and accurate dataset of steady-state profiles of selected downstream kinases of PDGF-receptor-alpha mutants in combination with inhibitor treatments. Applying the tool optPBN, we fitted a literature-derived candidate network model to the training dataset consisting of single perturbation conditions. Model analysis suggested several important crosstalk interactions. The validity of these predictions was further investigated experimentally pointing to relevant ongoing crosstalk from PI3K to MAPK signalling in tumour cells. The refined model was evaluated with a validation dataset comprising multiple perturbation conditions. The model thereby showed excellent performance allowing to quantitatively predict the combinatorial responses from the individual treatment results in this cancer setting. The established optPBN pipeline is also widely applicable to gain a better understanding of other signalling networks at steady-state in a context-specific fashion.
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5
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Haan S, Bahlawane C, Wang J, Nazarov PV, Muller A, Eulenfeld R, Haan C, Rolvering C, Vallar L, Satagopam VP, Sauter T, Wiesinger MY. The oncogenic FIP1L1-PDGFRα fusion protein displays skewed signaling properties compared to its wild-type PDGFRα counterpart. JAKSTAT 2015; 4:e1062596. [PMID: 26413425 PMCID: PMC4583054 DOI: 10.1080/21623996.2015.1062596] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/05/2015] [Accepted: 06/09/2015] [Indexed: 01/05/2023] Open
Abstract
Aberrant activation of oncogenic kinases is frequently observed in human cancers, but the underlying mechanism and resulting effects on global signaling are incompletely understood. Here, we demonstrate that the oncogenic FIP1L1-PDGFRα kinase exhibits a significantly different signaling pattern compared to its PDGFRα wild type counterpart. Interestingly, the activation of primarily membrane-based signal transduction processes (such as PI3-kinase- and MAP-kinase- pathways) is remarkably shifted toward a prominent activation of STAT factors. This diverging signaling pattern compared to classical PDGF-receptor signaling is partially coupled to the aberrant cytoplasmic localization of the oncogene, since membrane targeting of FIP1L1-PDGFRα restores activation of MAPK- and PI3K-pathways. In stark contrast to the classical cytokine-induced STAT activation process, STAT activation by FIP1L1-PDGFRα does neither require Janus kinase activity nor Src kinase activity. Furthermore, we investigated the mechanism of STAT5 activation via FIP1L1-PDGFRα in more detail and found that STAT5 activation does not involve an SH2-domain-mediated binding mechanism. We thus demonstrate that STAT5 activation occurs via a non-canonical activation mechanism in which STAT5 may be subject to a direct phosphorylation by FIP1L1-PDGFRα.
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Affiliation(s)
- Serge Haan
- Molecular Disease Mechanisms Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Christelle Bahlawane
- Molecular Disease Mechanisms Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Jiali Wang
- Molecular Disease Mechanisms Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Petr V Nazarov
- Genomics Research Unit; Luxembourg Institute of Health; Luxembourg , Luxembourg
| | - Arnaud Muller
- Genomics Research Unit; Luxembourg Institute of Health; Luxembourg , Luxembourg
| | - René Eulenfeld
- Signal Transduction Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Claude Haan
- Signal Transduction Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Catherine Rolvering
- Signal Transduction Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Laurent Vallar
- Genomics Research Unit; Luxembourg Institute of Health; Luxembourg , Luxembourg
| | - Venkata P Satagopam
- Luxembourg Center for Systems Biomedicine; University of Luxembourg ; Esch-sur-Alzette, Luxembourg
| | - Thomas Sauter
- Systems Biology Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
| | - Monique Yvonne Wiesinger
- Systems Biology Group; Life Sciences Research Unit; University of Luxembourg; Luxembourg , Luxembourg
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6
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F604S exchange in FIP1L1-PDGFRA enhances FIP1L1-PDGFRA protein stability via SHP-2 and SRC: a novel mode of kinase inhibitor resistance. Leukemia 2015; 29:1763-70. [DOI: 10.1038/leu.2015.70] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 11/08/2022]
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7
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Demoulin JB, Essaghir A. PDGF receptor signaling networks in normal and cancer cells. Cytokine Growth Factor Rev 2014; 25:273-83. [DOI: 10.1016/j.cytogfr.2014.03.003] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 03/10/2014] [Indexed: 01/05/2023]
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8
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Noël LA, Arts FA, Montano-Almendras CP, Cox L, Gielen O, Toffalini F, Marbehant CY, Cools J, Demoulin JB. The tyrosine phosphatase SHP2 is required for cell transformation by the receptor tyrosine kinase mutants FIP1L1-PDGFRα and PDGFRα D842V. Mol Oncol 2014; 8:728-40. [PMID: 24618081 DOI: 10.1016/j.molonc.2014.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/27/2014] [Accepted: 02/05/2014] [Indexed: 02/06/2023] Open
Abstract
Activated forms of the platelet derived growth factor receptor alpha (PDGFRα) have been described in various tumors, including FIP1L1-PDGFRα in patients with myeloproliferative diseases associated with hypereosinophilia and the PDGFRα(D842V) mutant in gastrointestinal stromal tumors and inflammatory fibroid polyps. To gain a better insight into the signal transduction mechanisms of PDGFRα oncogenes, we mutated twelve potentially phosphorylated tyrosine residues of FIP1L1-PDGFRα and identified three mutations that affected cell proliferation. In particular, mutation of tyrosine 720 in FIP1L1-PDGFRα or PDGFRα(D842V) inhibited cell growth and blocked ERK signaling in Ba/F3 cells. This mutation also decreased myeloproliferation in transplanted mice and the proliferation of human CD34(+) hematopoietic progenitors transduced with FIP1L1-PDGFRα. We showed that the non-receptor protein tyrosine phosphatase SHP2 bound directly to tyrosine 720 of FIP1L1-PDGFRα. SHP2 knock-down decreased proliferation of Ba/F3 cells transformed with FIP1L1-PDGFRα and PDGFRα(D842V) and affected ERK signaling, but not STAT5 phosphorylation. Remarkably, SHP2 was not essential for cell proliferation and ERK phosphorylation induced by the wild-type PDGF receptor in response to ligand stimulation, suggesting a shift in the function of SHP2 downstream of oncogenic receptors. In conclusion, our results indicate that SHP2 is required for cell transformation and ERK activation by mutant PDGF receptors.
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Affiliation(s)
- Laura A Noël
- de Duve Institute, Université catholique de Louvain, MEXP - UCL B1.74.05, Avenue Hippocrate 75, BE-1200 Brussels, Belgium.
| | - Florence A Arts
- de Duve Institute, Université catholique de Louvain, MEXP - UCL B1.74.05, Avenue Hippocrate 75, BE-1200 Brussels, Belgium.
| | - Carmen P Montano-Almendras
- de Duve Institute, Université catholique de Louvain, MEXP - UCL B1.74.05, Avenue Hippocrate 75, BE-1200 Brussels, Belgium.
| | - Luk Cox
- Center for The Biology of Disease, VIB, Herestraat 49, BE-3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, Leuven, Belgium.
| | - Olga Gielen
- Center for The Biology of Disease, VIB, Herestraat 49, BE-3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, Leuven, Belgium.
| | - Federica Toffalini
- de Duve Institute, Université catholique de Louvain, MEXP - UCL B1.74.05, Avenue Hippocrate 75, BE-1200 Brussels, Belgium.
| | - Catherine Y Marbehant
- de Duve Institute, Université catholique de Louvain, MEXP - UCL B1.74.05, Avenue Hippocrate 75, BE-1200 Brussels, Belgium.
| | - Jan Cools
- Center for The Biology of Disease, VIB, Herestraat 49, BE-3000 Leuven, Belgium; Center for Human Genetics, KU Leuven, Leuven, Belgium.
| | - Jean-Baptiste Demoulin
- de Duve Institute, Université catholique de Louvain, MEXP - UCL B1.74.05, Avenue Hippocrate 75, BE-1200 Brussels, Belgium.
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9
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A reactive oxygen species-mediated, self-perpetuating loop persistently activates platelet-derived growth factor receptor α. Mol Cell Biol 2013; 34:110-22. [PMID: 24190966 DOI: 10.1128/mcb.00839-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The platelet-derived growth factor (PDGF) receptors (PDGFRs) are central to a spectrum of human diseases. When PDGFRs are activated by PDGF, reactive oxygen species (ROS) and Src family kinases (SFKs) act downstream of PDGFRs to enhance PDGF-mediated tyrosine phosphorylation of various signaling intermediates. In contrast to these firmly established principles of signal transduction, much less is known regarding the recently appreciated ability of ROS and SFKs to indirectly and chronically activate monomeric PDGF receptor α (PDGFRα) in the setting of a blinding condition called proliferative vitreoretinopathy (PVR). In this context, we made a series of discoveries that substantially expands our appreciation of epigenetic-based mechanisms to chronically activate PDGFRα. Vitreous, which contains growth factors outside the PDGF family but little or no PDGFs, promoted formation of a unique SFK-PDGFRα complex that was dependent on SFK-mediated phosphorylation of PDGFRα and activated the receptor's kinase activity. While vitreous engaged a total of five receptor tyrosine kinases, PDGFRα was the only one that was activated persistently (at least 16 h). Prolonged activation of PDGFRα involved mTOR-mediated inhibition of autophagy and accumulation of mitochondrial ROS. These findings reveal that growth factor-containing biological fluids, such as vitreous, are able to tirelessly activate PDGFRα by engaging a ROS-mediated, self-perpetuating loop.
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10
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Walls CD, Iliuk A, Bai Y, Wang M, Tao WA, Zhang ZY. Phosphatase of regenerating liver 3 (PRL3) provokes a tyrosine phosphoproteome to drive prometastatic signal transduction. Mol Cell Proteomics 2013; 12:3759-77. [PMID: 24030100 DOI: 10.1074/mcp.m113.028886] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phosphatase of regenerating liver 3 (PRL3) is suspected to be a causative factor toward cellular metastasis when in excess. To date, the molecular basis for PRL3 function remains an enigma, making efforts at distilling a concerted mechanism for PRL3-mediated metastatic dissemination very difficult. We previously discovered that PRL3 expressing cells exhibit a pronounced increase in protein tyrosine phosphorylation. Here we take an unbiased mass spectrometry-based approach toward identifying the phosphoproteins exhibiting enhanced levels of tyrosine phosphorylation with a goal to define the "PRL3-mediated signaling network." Phosphoproteomic data support intracellular activation of an extensive signaling network normally governed by extracellular ligand-activated transmembrane growth factor, cytokine, and integrin receptors in the PRL3 cells. Additionally, data implicate the Src tyrosine kinase as the major intracellular kinase responsible for "hijacking" this network and provide strong evidence that aberrant Src activation is a major consequence of PRL3 overexpression. Importantly, the data support a PDGF(α/β)-, Eph (A2/B3/B4)-, and Integrin (β1/β5)-receptor array as being the predominant network coordinator in the PRL3 cells, corroborating a PRL3-induced mesenchymal-state. Within this network, we find that tyrosine phosphorylation is increased on a multitude of signaling effectors responsible for Rho-family GTPase, PI3K-Akt, STAT, and ERK activation, linking observations made by the field as a whole under Src as a primary signal transducer. Our phosphoproteomic data paint the most comprehensive picture to date of how PRL3 drives prometastatic molecular events through Src activation.
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Affiliation(s)
- Chad D Walls
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, Indiana 46202
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11
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Paugh BS, Zhu X, Qu C, Endersby R, Diaz AK, Zhang J, Bax DA, Carvalho D, Reis RM, Onar-Thomas A, Broniscer A, Wetmore C, Zhang J, Jones C, Ellison DW, Baker SJ. Novel oncogenic PDGFRA mutations in pediatric high-grade gliomas. Cancer Res 2013; 73:6219-29. [PMID: 23970477 DOI: 10.1158/0008-5472.can-13-1491] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The outcome for children with high-grade gliomas (HGG) remains dismal, with a 2-year survival rate of only 10% to 30%. Diffuse intrinsic pontine glioma (DIPG) comprise a subset of HGG that arise in the brainstem almost exclusively in children. Genome-wide analyses of copy number imbalances previously showed that platelet-derived growth factor receptor α (PDGFRA) is the most frequent target of focal amplification in pediatric HGGs, including DIPGs. To determine whether PDGFRA is also targeted by more subtle mutations missed by copy number analysis, we sequenced all PDGFRA coding exons from a cohort of pediatric HGGs. Somatic-activating mutations were identified in 14.4% (13 of 90) of nonbrainstem pediatric HGGs and 4.7% (2 of 43) of DIPGs, including missense mutations and in-frame deletions and insertions not previously described. Forty percent of tumors with mutation showed concurrent amplification, whereas 60% carried heterozygous mutations. Six different mutations impacting different domains all resulted in ligand-independent receptor activation that was blocked by small molecule inhibitors of PDGFR. Expression of mutants in p53-null primary mouse astrocytes conferred a proliferative advantage in vitro and generated HGGs in vivo with complete penetrance when implanted into brain. The gene expression signatures of these murine HGGs reflected the spectrum of human diffuse HGGs. PDGFRA intragenic deletion of exons 8 and 9 were previously shown in adult HGG, but were not detected in 83 nonbrainstem pediatric HGG and 57 DIPGs. Thus, a distinct spectrum of mutations confers constitutive receptor activation and oncogenic activity to PDGFRα in childhood HGG.
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Affiliation(s)
- Barbara S Paugh
- Authors' Affiliations: Departments of Developmental Neurobiology, Computational Biology, Biostatistics, Oncology, and Pathology, St. Jude Children's Research Hospital; Interdisciplinary Biomedical Science Program, University of Tennessee Health Sciences Center, Memphis, Tennessee; Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, Perth, Australia; Divisions of Molecular Pathology and Cancer Therapeutics, The Institute of Cancer Research, London, United Kingdom; and Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos, São Paulo, Brazil
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12
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Spangle JM, Munger K. The HPV16 E6 oncoprotein causes prolonged receptor protein tyrosine kinase signaling and enhances internalization of phosphorylated receptor species. PLoS Pathog 2013; 9:e1003237. [PMID: 23516367 PMCID: PMC3597533 DOI: 10.1371/journal.ppat.1003237] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 01/28/2013] [Indexed: 01/13/2023] Open
Abstract
The high-risk human papillomavirus (HPV) E6 proteins are consistently expressed in HPV-associated lesions and cancers. HPV16 E6 sustains the activity of the mTORC1 and mTORC2 signaling cascades under conditions of growth factor deprivation. Here we report that HPV16 E6 activated mTORC1 by enhanced signaling through receptor protein tyrosine kinases, including epidermal growth factor receptor and insulin receptor and insulin-like growth factor receptors. This is evidenced by sustained signaling through these receptors for several hours after growth factor withdrawal. HPV16 E6 increased the internalization of activated receptor species, and the signaling adaptor protein GRB2 was shown to be critical for HPV16 E6 mediated enhanced EGFR internalization and mTORC1 activation. As a consequence of receptor protein kinase mediated mTORC1 activation, HPV16 E6 expression increased cellular migration of primary human epithelial cells. This study identifies a previously unappreciated mechanism by which HPV E6 proteins perturb host-signaling pathways presumably to sustain protein synthesis during the viral life cycle that may also contribute to cellular transforming activities of high-risk HPV E6 proteins. High-risk human papillomavirus infections are associated with nearly all cases of cervical cancer. HPVs infect basal epithelial cells but virion production is restricted to the outer, terminally differentiated layers of the infected epithelia where supply of nutrients and growth factors may be limited. High-risk HPV E6 proteins have been shown to activate mTORC1 signaling and increase cap dependent translation. Here we show that HPV16 E6 activates the mTORC1 and MAP kinase signaling pathways through activating receptor protein tyrosine kinases (RPTKs) and increases EGFR internalization, even after growth factor withdrawal. The signaling adaptor protein GRB2 is a critical mediator of HPV16 E6 mediated EGFR internalization and mTORC1 activation. Lastly, we demonstrate that HPV16 E6 mediated activation of RPTK and mTORC1 signaling causes increased cellular migration even after growth factor withdrawal. These results suggest a previously unappreciated mechanism by which HPV E6 proteins may support the viral life cycle and that may contribute to the transforming activities of high-risk HPV E6 proteins. Hence, inhibition of RPTK signaling networks may be evaluated as a therapeutic strategy for HPV-associated lesions and cancers.
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Affiliation(s)
- Jennifer M. Spangle
- Division of Infectious Diseases, Brigham and Women's Hospital, Department of Medicine and Committee on Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Karl Munger
- Division of Infectious Diseases, Brigham and Women's Hospital, Department of Medicine and Committee on Virology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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13
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Locascio LE, Donoghue DJ. KIDs rule: regulatory phosphorylation of RTKs. Trends Biochem Sci 2013; 38:75-84. [PMID: 23312584 DOI: 10.1016/j.tibs.2012.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 11/29/2012] [Accepted: 12/03/2012] [Indexed: 01/14/2023]
Abstract
Receptor tyrosine kinases (RTKs) are mediators of multiple cell signaling networks linked to cell growth and differentiation. In general, they exhibit similar overall structure with a ligand-binding extracellular domain and a conserved intracellular tyrosine kinase domain. In many RTKs, the kinase domain is interrupted by a sequence known as the kinase insert domain (KID). In addition to phosphorylation sites within the kinase domain, regulatory phosphorylation also occurs within the KID of several RTKs important in human health and disease. Phosphorylation of specific Tyr or Ser residues within the KID of some RTKs triggers distinct cellular signaling outcomes. Here, we review the functionality of KIDs throughout all RTK families, and provide justification for further study of this often-overlooked domain.
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Affiliation(s)
- Lauren E Locascio
- Department of Chemistry and Biochemistry, Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA 92093-0367, USA
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14
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Selected reaction monitoring mass spectrometry reveals the dynamics of signaling through the GRB2 adaptor. Nat Biotechnol 2011; 29:653-8. [PMID: 21706016 DOI: 10.1038/nbt.1905] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 06/03/2011] [Indexed: 12/25/2022]
Abstract
Signaling pathways are commonly organized through inducible protein-protein interactions, mediated by adaptor proteins that link activated receptors to cytoplasmic effectors. However, we have little quantitative data regarding the kinetics with which such networks assemble and dissolve to generate specific cellular responses. To address this deficiency, we designed a mass spectrometry method, affinity purification-selected reaction monitoring (AP-SRM), which we used to comprehensively and quantitatively investigate changes in protein interactions with GRB2, an adaptor protein that participates in a remarkably diverse set of protein complexes involved in multiple aspects of cellular function. Our data reliably define context-specific and time-dependent networks that form around GRB2 after stimulation, and reveal core and growth factor-selective complexes comprising 90 proteins identified as interacting with GRB2 in HEK293T cells. Capturing a key hub protein and dissecting its interactions by SRM should be equally applicable to quantifying signaling dynamics for a range of hubs in protein interaction networks.
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15
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Novel imatinib-sensitive PDGFRA-activating point mutations in hypereosinophilic syndrome induce growth factor independence and leukemia-like disease. Blood 2011; 117:2935-43. [DOI: 10.1182/blood-2010-05-286757] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Abstract
The FIP1L1-PDGFRA fusion is seen in a fraction of cases with a presumptive diagnosis of hypereosinophilic syndrome (HES). However, because most HES patients lack FIP1L1-PDGFRA, we studied whether they harbor activating mutations of the PDGFRA gene. Sequencing of 87 FIP1L1-PDGFRA–negative HES patients revealed several novel PDGFRA point mutations (R481G, L507P, I562M, H570R, H650Q, N659S, L705P, R748G, and Y849S). When cloned into 32D cells, N659S and Y849S and—on selection for high expressors—also H650Q and R748G mutants induced growth factor–independent proliferation, clonogenic growth, and constitutive phosphorylation of PDGFRA and Stat5. Imatinib antagonized Stat5 phosphorylation. Mutations involving positions 659 and 849 had been shown previously to possess transforming potential in gastrointestinal stromal tumors. Because H650Q and R748G mutants possessed only weak transforming activity, we injected 32D cells harboring these mutants or FIP1L1-PDGFRA into mice and found that they induced a leukemia-like disease. Oral imatinib treatment significantly decreased leukemic growth in vivo and prolonged survival. In conclusion, our data provide evidence that imatinib-sensitive PDGFRA point mutations play an important role in the pathogenesis of HES and we propose that more research should be performed to further define the frequency and treatment response of PDGFRA mutations in FIP1L1-PDGFRA–negative HES patients.
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16
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Sustained platelet-derived growth factor receptor alpha signaling in osteoblasts results in craniosynostosis by overactivating the phospholipase C-gamma pathway. Mol Cell Biol 2008; 29:881-91. [PMID: 19047372 DOI: 10.1128/mcb.00885-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The development and growth of the skull is controlled by cranial sutures, which serve as growth centers for osteogenesis by providing a pool of osteoprogenitors. These osteoprogenitors undergo intramembranous ossification by direct differentiation into osteoblasts, which synthesize the components of the extracellular bone matrix. A dysregulation of osteoblast differentiation can lead to premature fusion of sutures, resulting in an abnormal skull shape, a disease called craniosynostosis. Although several genes could be linked to craniosynostosis, the mechanisms regulating cranial suture development remain largely elusive. We have established transgenic mice conditionally expressing an autoactivated platelet-derived growth factor receptor alpha (PDGFRalpha) in neural crest cells (NCCs) and their derivatives. In these mice, premature fusion of NCC-derived sutures occurred at early postnatal stages. In vivo and in vitro experiments demonstrated enhanced proliferation of osteoprogenitors and accelerated ossification of osteoblasts. Furthermore, in osteoblasts expressing the autoactivated receptor, we detected an upregulation of the phospholipase C-gamma (PLC-gamma) pathway. Treatment of differentiating osteoblasts with a PLC-gamma-specific inhibitor prevented the mineralization of synthesized bone matrix. Thus, we show for the first time that PDGFRalpha signaling stimulates osteogenesis of NCC-derived osteoblasts by activating the PLC-gamma pathway, suggesting an involvement of this pathway in the etiology of human craniosynostosis.
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17
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Bäumer AT, ten Freyhaus H, Sauer H, Wartenberg M, Kappert K, Schnabel P, Konkol C, Hescheler J, Vantler M, Rosenkranz S. Phosphatidylinositol 3-Kinase-dependent Membrane Recruitment of Rac-1 and p47phox Is Critical for α-Platelet-derived Growth Factor Receptor-induced Production of Reactive Oxygen Species. J Biol Chem 2008; 283:7864-76. [DOI: 10.1074/jbc.m704997200] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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18
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Smith D, Shimamura T, Barbera S, Bejcek BE. NF-kappaB controls growth of glioblastomas/astrocytomas. Mol Cell Biochem 2007; 307:141-7. [PMID: 17828582 DOI: 10.1007/s11010-007-9593-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 08/23/2007] [Indexed: 01/06/2023]
Abstract
NF-kappaB is a family of transcription factors that have been shown to be elevated in a variety of tumor types and in some cases central to their survival and growth. Here we present evidence that U-87 MG and U-118 MG growth is regulated by NF-kappaB and controlled by PDGF. NF-kappaB activity was suppressed by a dominant negative mutant of the human PDGF type beta receptor and PDGF-B chain neutralizing antibodies. Creation of cell lines that had inducible expression of shRNAs directed against either c-Rel or RelA inhibited growth almost 90% indicating that NF-kappaB plays a central role in glioblastoma growth.
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Affiliation(s)
- Denise Smith
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA
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19
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Vantler M, Huntgeburth M, Caglayan E, Ten Freyhaus H, Schnabel P, Rosenkranz S. PI3-kinase/Akt-dependent antiapoptotic signaling by the PDGF alpha receptor is negatively regulated by Src family kinases. FEBS Lett 2006; 580:6769-76. [PMID: 17141222 DOI: 10.1016/j.febslet.2006.11.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 11/10/2006] [Indexed: 11/18/2022]
Abstract
Regulation of growth factor dependent cell survival is crucial for development and disease progression. Here, we report a novel function of Src kinases as a negative regulator of platelet-derived growth factor (PDGF) dependent cell survival. We characterized a series of PDGF alpha receptor (PDGFRA) mutants, which lack the binding sites for Src, phosphatidylinositol 3'-kinase (PI3K), SHP-2 or phospholipase C-gamma. We found that PDGFRA-dependent cell survival was mainly mediated through activation of PI3K, and was negatively regulated by Src. Characterization of the downstream signaling events revealed that PI3K activates the protein kinase Akt, which in turn phosphorylates and thus inactivates proapoptotic Forkhead transcription factors. Src phosphorylates the ubiquitin-ligase c-Cbl, which is required for degradation of the activated receptor. Consequently, overexpression of c-Cbl prevented PDGFRA-mediated cell survival, whereas it did not affect this response, when Src was unable to associate with the receptor. This novel function of Src in antiapoptotic signaling introduces Src kinases as an interesting therapeutic target in apoptosis related diseases.
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Affiliation(s)
- Marius Vantler
- Klinik III für Innere Medizin, Universität zu Köln, Kerpener Strasse 62, D-50924 Köln, Germany
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20
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Pallante BA, Duignan I, Okin D, Chin A, Bressan MC, Mikawa T, Edelberg JM. Bone marrow Oct3/4+ cells differentiate into cardiac myocytes via age-dependent paracrine mechanisms. Circ Res 2006; 100:e1-11. [PMID: 17122441 DOI: 10.1161/01.res.0000253487.02398.85] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The mechanisms that govern the capacity of the bone marrow stem cells to generate cardiac myocytes are still unknown. Herein we demonstrate that the cardiomyogenic potential of bone marrow-derived Oct3/4(+)/cKit(+/-)/CXCR4(+/-)/CD34(-)/Sca1(-) cells is governed by age-dependent paracrine/juxtacrine platelet-derived growth factor (PDGF) pathways. Specifically, bone marrow cell cultures from both 3- and 18-month-old mice formed aggregates of Oct3/4(+) cells circumscribed by PDGFRalpha(+)/Oct3/4(-)/Sca1(+) cells. In young (3-month) bone marrow cell cultures, induction of PDGF-AB preceded the induction of cardiac genes and was required for the generation of cardiomyogenesis. Indeed, in old (18-month) cultures, diminished PDGF-B induction was associated with impaired cardiomyogenic potential, despite having Oct3/4 levels similar to those in the young cells. Importantly, supplementation with PDGF-AB specifically restored the cardiac differentiation capacity of the old bone marrow cells. Together these results demonstrate that, regardless of age, the bone marrow niche contains Oct3/4 stem cells that are capable of differentiating into cardiac myocytes. Moreover, this differentiation is governed by age-dependent PDGF-AB-mediated paracrine/juxtacrine pathways that may be essential in the translation of bone marrow cell-mediated cardiomyogenesis.
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Affiliation(s)
- Benedetta A Pallante
- Departments of Medicine, Weill Medical College of Cornell University, New York, USA
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21
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Schneider L, Clement CA, Teilmann SC, Pazour GJ, Hoffmann EK, Satir P, Christensen ST. PDGFRalphaalpha signaling is regulated through the primary cilium in fibroblasts. Curr Biol 2006; 15:1861-6. [PMID: 16243034 DOI: 10.1016/j.cub.2005.09.012] [Citation(s) in RCA: 457] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 09/01/2005] [Accepted: 09/01/2005] [Indexed: 11/28/2022]
Abstract
Recent findings show that cilia are sensory organelles that display specific receptors and ion channels, which transmit signals from the extracellular environment via the cilium to the cell to control tissue homeostasis and function. Agenesis of primary cilia or mislocation of ciliary signal components affects human pathologies, such as polycystic kidney disease and disorders associated with Bardet-Biedl syndrome. Primary cilia are essential for hedgehog ligand-induced signaling cascade regulating growth and patterning. Here, we show that the primary cilium in fibroblasts plays a critical role in growth control via platelet-derived growth factor receptor alpha (PDGFRalpha), which localizes to the primary cilium during growth arrest in NIH3T3 cells and primary cultures of mouse embryonic fibroblasts. Ligand-dependent activation of PDGFRalphaalpha is followed by activation of Akt and the Mek1/2-Erk1/2 pathways, with Mek1/2 being phosphorylated within the cilium and at the basal body. Fibroblasts derived from Tg737(orpk) mutants fail to form normal cilia and to upregulate the level of PDGFRalpha; PDGF-AA fails to activate PDGFRalphaalpha and the Mek1/2-Erk1/2 pathway. Signaling through PDGFRbeta, which localizes to the plasma membrane, is maintained at comparable levels in wild-type and mutant cells. We propose that ciliary PDGFRalphaalpha signaling is linked to tissue homeostasis and to mitogenic signaling pathways.
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Affiliation(s)
- Linda Schneider
- Department of Biochemistry, Institute for Molecular Biology and Physiology, University of Copenhagen, The August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
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22
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Imhof D, Wavreille AS, May A, Zacharias M, Tridandapani S, Pei D. Sequence specificity of SHP-1 and SHP-2 Src homology 2 domains. Critical roles of residues beyond the pY+3 position. J Biol Chem 2006; 281:20271-82. [PMID: 16702225 DOI: 10.1074/jbc.m601047200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A combinatorial phosphotyrosyl (pY) peptide library was screened to determine the amino acid preferences at the pY+4 to pY+6 positions for the four SH2 domains of protein-tyrosine phosphatases SHP-1 and SHP-2. Individual binding sequences selected from the library were resynthesized and their binding affinities and specificities to various SH2 domains were further evaluated by SPR studies, stimulation of SHP-1 and SHP-2 phosphatase activity, and in vitro pulldown assays. These studies reveal that binding of a pY peptide to the N-SH2 domain of SHP-2 is greatly enhanced by a large hydrophobic residue (Trp, Tyr, Met, or Phe) at the pY+4 and/or pY+5 positions, whereas binding to SHP-1 N-SH2 domain is enhanced by either hydrophobic or positively charged residues (Arg, Lys, or His) at these positions. Similar residues at the pY+4 to pY+6 positions are also preferred by SHP-1 and SHP-2 C-SH2 domains, although their influence on the overall binding affinities is much smaller compared with the N-SH2 domains. A structural model was generated to qualitatively interpret the contribution of the pY+4 and pY+5 residues to the overall binding affinity. Examination of pY motifs from known SHP-1 and SHP-2-binding proteins shows that many of the pY motifs contain a hydrophobic or positively charged residue(s) at the pY+4 and pY+5 positions.
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Affiliation(s)
- Diana Imhof
- Department of Chemistry, Ohio State University, Columbus, Ohio 43210, USA
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23
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Xu WH, Wang YS, Liu GZ, Chen X, Tinjuangjun P, Pi LY, Song WY. The autophosphorylated Ser686, Thr688, and Ser689 residues in the intracellular juxtamembrane domain of XA21 are implicated in stability control of rice receptor-like kinase. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 45:740-51. [PMID: 16460508 DOI: 10.1111/j.1365-313x.2005.02638.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The rice gene Xa21 confers resistance against Xanthomonas oryzae pv. oryzae (Xoo). Xa21 encodes a receptor-like kinase (XA21). We demonstrate that XA21 autophosphorylates residues Ser686, Thr688 and Ser689 in vitro. Substitution of these residues with alanines did not affect the autophosphorylation function of this kinase, but specifically destabilized the resistance protein in vitro and in vivo. Plants carrying these same substitutions in XA21 were compromised in their resistance to the normally avirulent Xoo Philippine race 6. Additionally, we show that wild-type XA21 and the kinase-dead mutant with the invariable Lys736 residue mutated to glutamic acid were also proteolytically degraded in protein extracts. Finally, we show a correlation between the in vitro degradation and in vivo instability of the proteins. We propose that autophosphorylation of Ser686, Thr688 and Ser689 functions to stabilize XA21 against the developmentally controlled proteolytic activity.
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Affiliation(s)
- Wei-Hui Xu
- Department of Plant Pathology, Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32611, USA
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24
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Chen KT, Lin JD, Liou MJ, Weng HF, Chang CA, Chan EC. An aberrant autocrine activation of the platelet-derived growth factor alpha-receptor in follicular and papillary thyroid carcinoma cell lines. Cancer Lett 2005; 231:192-205. [PMID: 16126335 DOI: 10.1016/j.canlet.2005.01.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2004] [Revised: 01/30/2005] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
Platelet-derived growth factor receptor (PDGFR) can bind to its ligand and consequently possess a kinase activity, and which is associated with the carcinogenesis of different cell types, including astrocytomas, oligodendrogliomas, and glioblastoma. In a cDNA microarray analysis, we observe the over-expressed mRNA of both PDGF-A and PDGF-alpha receptor in thyroid carcinoma cells. And the elevated protein expressions of PDGF-A and PDGF-alpha receptor in thyroid carcinoma cells were also confirmed by a Western blot analysis. The phosphorylation of PDGF-alpha receptor evaluated by an antibody against Tyr 720-phosphate was found in thyroid carcinoma cells. The tyrosine kinase activity of PDGF-alpha receptor was inhibited by tyrphostin AG1295 and showed a dose-dependent inhibition for the proliferation of thyroid carcinoma cells. These findings imply that autocrine activation of PDGF-alpha receptor plays a crucial role in the carcinogenesis of thyroid cells.
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MESH Headings
- Adenocarcinoma, Follicular/genetics
- Adenocarcinoma, Follicular/metabolism
- Adenocarcinoma, Papillary/genetics
- Adenocarcinoma, Papillary/metabolism
- Autocrine Communication
- Blotting, Western
- Cell Proliferation/drug effects
- DNA, Complementary
- Enzyme Activation
- Gene Expression Profiling
- Humans
- Oligonucleotide Array Sequence Analysis
- Phosphorylation
- Platelet-Derived Growth Factor/genetics
- Platelet-Derived Growth Factor/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Platelet-Derived Growth Factor alpha/genetics
- Receptor, Platelet-Derived Growth Factor alpha/metabolism
- Thyroid Neoplasms/genetics
- Thyroid Neoplasms/metabolism
- Tumor Cells, Cultured
- Tyrosine/metabolism
- Tyrphostins/pharmacology
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Affiliation(s)
- Kuei-Tien Chen
- School of Medical Technology, Chang Gung University, Taoyuan, Taiwan
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25
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Van Stry M, Kazlauskas A, Schreiber SL, Symes K. Distinct effectors of platelet-derived growth factor receptor-alpha signaling are required for cell survival during embryogenesis. Proc Natl Acad Sci U S A 2005; 102:8233-8. [PMID: 15919820 PMCID: PMC1149433 DOI: 10.1073/pnas.0502885102] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Platelet-derived growth factor receptor (PDGFR) signaling is essential for normal embryonic development in many organisms, including frog, mouse, zebrafish, and sea urchin. The mode of action of PDGFR signaling during early development is poorly understood, however, mostly because inhibition of signaling through either the PDGFRalpha or PDGFRbeta is embryonic lethal. In Xenopus embryos, disruption of PDGFRalpha signaling causes migrating anterior mesoderm cells to lose direction and undergo apoptosis through the mitochondrial pathway. To understand the mechanism of PDGFRalpha function in this process, we have analyzed all known effector-binding sites in vivo. By using a chemical inducer of dimerization to activate chimera PDGFRalphas, we have identified a role for phospholipase Cgamma (PLCgamma) in protecting cells from death. PDGFRalpha-mediated cell survival requires PLCgamma and phosphatidylinositol 3-kinase signaling, and that PDGFRalpha with binding sites for these two signaling factors is sufficient for this activity. Other effectors of PDGFRalpha signaling, Shf, SHP-2, and Crk, are not required for this process. Thus, our findings show that PDGFRalpha signaling through PLCgamma and phosphatidylinositol 3-kinase has a protective role in preventing apoptosis in early development. Furthermore, we demonstrate that small molecule inducers of dimerization provide a powerful system to manipulate receptor function in developing embryos.
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Affiliation(s)
- Melanie Van Stry
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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26
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Arnaud M, Mzali R, Gesbert F, Crouin C, Guenzi C, Vermot-Desroches C, Wijdenes J, Courtois G, Bernard O, Bertoglio J. Interaction of the tyrosine phosphatase SHP-2 with Gab2 regulates Rho-dependent activation of the c-fos serum response element by interleukin-2. Biochem J 2004; 382:545-56. [PMID: 15170389 PMCID: PMC1133811 DOI: 10.1042/bj20040103] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Revised: 05/17/2004] [Accepted: 06/01/2004] [Indexed: 12/27/2022]
Abstract
Gab2 (Grb2-associated binder-2), a member of the IRS (insulin receptor substrate)/Gab family of adapter proteins, undergoes tyrosine phosphorylation in response to cytokine or growth factor stimulation and serves as a docking platform for many signal transduction effectors, including the tyrosine phosphatase SHP-2 [SH2 (Src homology 2)-domain-containing tyrosine phosphatase]. Here, we report that, following IL-2 (interleukin-2) stimulation of human T lymphocytes, SHP-2 binds tyrosine residues 614 and 643 of human Gab2 through its N- and C-terminal SH2 domains respectively. However, the sole mutation of Tyr-614 into phenylalanine is sufficient to prevent Gab2 from recruiting SHP-2. Expression of the Gab2 Tyr-614-->Phe (Y614F) mutant, defective in SHP-2 association, prevents ERK (extracellular-signal-regulated kinase) activation and expression of a luciferase reporter plasmid driven by the c-fos SRE (serum response element), indicating that interaction of SHP-2 with Gab2 is required for ERK activation in response to IL-2. Further investigation of IL-2-dependent induction of SRE showed that expression of a constitutively active mutant of the RhoA GTPase synergizes with IL-2 for SRE-driven transcription, whereas a dominant-negative mutant reduces the IL-2 response. Thus, in response to IL-2, full induction of the SRE requires ERK-dependent as well as Rho-dependent signals that target the Ets-box and the CArG-box respectively. We also report that the synergy between Gab2/SHP-2 and RhoA for IL-2-dependent CArG-box-driven transcription depends upon MEK (mitogen-activated protein kinase/ERK kinase) activation, and is likely to involve regulation of the serum response factor co-activator MAL. Our studies thus provide new insights into the role of Gab2 and SHP-2 in IL-2 signal transduction.
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Key Words
- c-fos
- grb2-associated binder 2 (gab2)
- interleukin 2 (il-2)
- mitogen-activated protein (map) kinase
- rho gtpase
- serum response element (sre)
- sh2-domain-containing tyrosine phosphatase (shp-2)
- ecl, enhanced chemiluminescence
- erk, extracellular-signal-regulated kinase
- gab2, grb2-associated binder-2
- gst, glutathione s-transferase
- ha, haemagglutinin
- il, interleukin
- iptg, isopropyl β-d-thiogalactoside
- irs, insulin receptor substrate
- jak, janus kinase
- mapk, mitogen-activated protein kinase
- mek, mapk/erk kinase
- pdgf-r, platelet-derived growth factor receptor
- pi3k, phosphoinositide 3-kinase
- sre, serum response element
- srf, serum response factor
- sh2, src homology 2
- shp-2, sh2-domain-containing tyrosine phosphatase
- stat, signal transduction and activators of transcription
- tcf, ternary complex factor
- y614f, etc., a mutant bearing a replacement of tyr-614 with phenylalanine, etc
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Affiliation(s)
- Mary Arnaud
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Rym Mzali
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Franck Gesbert
- †Unité de Biologie des Interactions Cellulaires, Institut Pasteur, 25 rue du docteur Roux, 75015 Paris, France
| | - Catherine Crouin
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Christine Guenzi
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | | | - John Wijdenes
- ‡Diaclone, 1 Boulevard A. Fleming, 25020 Besançon, France
| | - Geneviève Courtois
- §Inserm EMI0210, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France
| | - Olivier Bernard
- §Inserm EMI0210, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France
| | - Jacques Bertoglio
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
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27
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Abstract
We have investigated the regulation of protein tyrosine phosphatases (PTPs) by reactive oxygen species (ROS) in a cellular environment. We demonstrate that multiple PTPs were reversibly oxidized and inactivated following treatment of Rat-1 cells with H(2)O(2) and that inhibition of PTP function was important for ROS-induced mitogenesis. Furthermore, we show transient oxidation of the SH2 domain containing PTP, SHP-2, in response to PDGF that requires association with the PDGFR. Our results indicate that SHP-2 inhibits PDGFR signaling and suggest a mechanism by which autophosphorylation of the PDGFR occurs despite its association with SHP-2. The data suggest that several PTPs may be regulated by oxidation and that characterization of this process may define novel links between specific PTPs and particular signaling pathways in vivo.
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Affiliation(s)
- Tzu-Ching Meng
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
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28
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Esposito DL, Li Y, Cama A, Quon MJ. Tyr(612) and Tyr(632) in human insulin receptor substrate-1 are important for full activation of insulin-stimulated phosphatidylinositol 3-kinase activity and translocation of GLUT4 in adipose cells. Endocrinology 2001; 142:2833-40. [PMID: 11416002 DOI: 10.1210/endo.142.7.8283] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To examine contributions of specific YXXM motifs in human insulin receptor substrate-1 (IRS-1) to mediating the metabolic actions of insulin, we studied IRS-1 mutants containing various substitutions of Phe for Tyr. In transfected NIH-3T3(IR) cells, insulin stimulation caused a 5-fold increase in phosphatidylinositol 3-kinase (PI3K) activity coimmunoprecipitated with wild-type IRS-1. No PI3K activity was associated with IRS1-F6 (Phe substituted for Tyr at positions 465, 612, 632, 662, 941, and 989). Adding back both Tyr(612) and Tyr(632) fully restored IRS-1-associated PI3K activity, whereas adding back either Tyr(612) or Tyr(632) alone was associated with intermediate PI3K activity. In rat adipose cells transfected with epitope-tagged GLUT4, insulin stimulation caused a 2-fold increase in cell surface GLUT4-HA. Cotransfection of cells with GLUT4-HA and either wild-type IRS-1 or IRS1-Y612/Y632 increased basal cell surface GLUT4-HA (in the absence of insulin) to approximately 80% of the levels seen in insulin-stimulated control cells, whereas overexpression of IRS1-F6 had no effect on the insulin dose-response curve. Overexpression of IRS1-Y612 or IRS1-Y632 caused intermediate effects. Thus, both Tyr(612) and Tyr(632) are important for IRS-1 to fully activate PI3K and mediate translocation of GLUT4 in response to insulin.
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Affiliation(s)
- D L Esposito
- Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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29
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Ong SH, Hadari YR, Gotoh N, Guy GR, Schlessinger J, Lax I. Stimulation of phosphatidylinositol 3-kinase by fibroblast growth factor receptors is mediated by coordinated recruitment of multiple docking proteins. Proc Natl Acad Sci U S A 2001; 98:6074-9. [PMID: 11353842 PMCID: PMC33424 DOI: 10.1073/pnas.111114298] [Citation(s) in RCA: 247] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The docking protein FRS2 is a major downstream effector that links fibroblast growth factor (FGF) and nerve growth factor receptors with the Ras/mitogen-activated protein kinase signaling cascade. In this report, we demonstrate that FRS2 also plays a pivotal role in FGF-induced recruitment and activation of phosphatidylinositol 3-kinase (PI3-kinase). We demonstrate that tyrosine phosphorylation of FRS2alpha leads to Grb2-mediated complex formation with the docking protein Gab1 and its tyrosine phosphorylation, resulting in the recruitment and activation of PI3-kinase. Furthermore, Grb2 bound to tyrosine-phosphorylated FRS2 through its SH2 domain interacts primarily via its carboxyl-terminal SH3 domain with a proline-rich region in Gab1 and via its amino-terminal SH3 domain with the nucleotide exchange factor Sos1. Assembly of FRS2alpha:Grb2:Gab1 complex induced by FGF stimulation results in activation of PI3-kinase and downstream effector proteins such as the S/T kinase Akt, whose cellular localization and activity are regulated by products of PI3-kinase. These experiments reveal a unique mechanism for generation of signal diversity by growth factor-induced coordinated assembly of a multidocking protein complex that can activate the Ras/mitogen-activated protein kinase cascade to induce cell proliferation and differentiation, and PI3-kinase to activate a mediator of a cell survival pathway.
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Affiliation(s)
- S H Ong
- Department of Pharmacology and The Skirball Institute, New York University, Medical School, New York, NY 10016, USA
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30
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Klinghoffer RA, Mueting-Nelsen PF, Faerman A, Shani M, Soriano P. The two PDGF receptors maintain conserved signaling in vivo despite divergent embryological functions. Mol Cell 2001; 7:343-54. [PMID: 11239463 DOI: 10.1016/s1097-2765(01)00182-4] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Gene targeting studies have indicated that the two receptors for PDGF, alpha and beta, direct unique functions during development. Distinct ligand affinities, patterns of gene expression, and/or mechanisms of signal relay may account for functional specificity of the two PDGF receptor isoforms. To distinguish between these factors, we have created two complementary lines of knockin mice in which the intracellular signaling domains of one PDGFR have been removed and replaced by those of the other PDGFR. While both lines demonstrated substantial rescue of normal development, substitution of the PDGFbetaR signaling domains with those of the PDGFalphaR resulted in varying degrees of vascular disease. This observation provides a framework for discussing the evolution of receptor tyrosine kinase functional specificity.
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Affiliation(s)
- R A Klinghoffer
- Program in Developmental Biology and Division, Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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31
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Ali S, Ali S. Recruitment of the protein-tyrosine phosphatase SHP-2 to the C-terminal tyrosine of the prolactin receptor and to the adaptor protein Gab2. J Biol Chem 2000; 275:39073-80. [PMID: 10991949 DOI: 10.1074/jbc.m007478200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein-tyrosine phosphatase SHP-2 modulates signaling events through receptor tyrosine kinases and cytokine receptors including the receptor for prolactin (PRLR). Here we investigated mechanisms of SHP-2 recruitment within the PRLR signaling complex. Using SHP-2 and PRLR immunoprecipitation studies in 293 cells and in the mouse mammary epithelial cell line HC11, we found that SHP-2 co-immunoprecipitates with the PRLR and that the C-terminal tyrosine of the PRLR plays a regulatory role in both the tyrosine phosphorylation and the recruitment of SHP-2. Our results further indicate that SHP-2 association to the PRLR occurs via the C-terminal SH2 domain of the phosphatase. In addition, we determined that the newly identified adaptor protein Gab2, but not Gab1, is specifically tyrosine phosphorylated and is able to recruit SHP-2 and phosphatidyinositol 3-kinase in response to PRLR activation. Together, these studies suggest the presence of dual recruitment sites for SHP-2; the first is to the C-terminal tyrosine of the PRLR and the second is to the adaptor protein Gab2.
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Affiliation(s)
- S Ali
- Department of Medicine, Division of Hematology and Molecular Oncology Group, Royal Victoria Hospital, McGill University, Montreal, Quebec H3A 1A1, Canada
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32
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Selheim F, Fukami MH, Holmsen H, Vassbotn FS. Platelet-derived-growth-factor-induced signalling in human platelets: phosphoinositide-3-kinase-dependent inhibition of platelet activation. Biochem J 2000; 350 Pt 2:469-75. [PMID: 10947961 PMCID: PMC1221274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Human platelets release platelet-derived growth factor (PDGF) from alpha-granules during platelet activation. We have previously shown that platelets have PDGF alpha-receptors, a transmembrane tyrosine kinase that takes part in negative feedback regulation during platelet activation. Here we have described a study of PDGF-induced tyrosine phosphorylation of platelet substrates and phosphoinositide 3-kinase (PI-3K) activity in collagen-stimulated platelets. By immunoblotting with phosphotyrosine antibodies of collagen-activated platelets we found that PDGF increased the phosphorylation of several platelet substrates, e.g. pp140, pp120 and pp85. PDGF inhibited collagen-induced platelet activation in the presence of inhibitors of autocrine stimulation, thus blocking the pure collagen-induced signal transduction. PDGF enhanced the collagen-induced formation of PtdIns(3,4)P(2) and PtdIns(3,4,5)P(3) as measured by HPLC. Wortmannin and LY294002, two unrelated inhibitors of PI-3K, were used to investigate the role of PI-3K in PDGF-induced platelet signalling. Incubation of platelets with wortmannin and LY294002 blocked the formation of three phosphorylated inositides as well as the inhibitory effect of PDGF on collagen-induced platelet activation. We conclude that the inhibitory effect of PDGF on platelet activation is PI-3K dependent. This is the first demonstration of a negative regulatory function of 3-phosphorylated inositides in platelets.
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Affiliation(s)
- F Selheim
- Department of Biochemistry and Molecular Biology, University of Bergen, Arstadveien 19, N-5009 Bergen, Norway.
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33
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Hooshmand-Rad R, Lu L, Heldin CH, Claesson-Welsh L, Welsh M. Platelet-derived growth factor-mediated signaling through the Shb adaptor protein: effects on cytoskeletal organization. Exp Cell Res 2000; 257:245-54. [PMID: 10837138 DOI: 10.1006/excr.2000.4896] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Src homology (SH) 2 domain adaptor protein Shb has previously been shown to interact with the platelet-derived growth factor (PDGF)-beta receptor. In this study we show an association between Shb and the PDGF-alpha receptor which is mediated by the SH2 domain of Shb and involves tyrosine residue 720 in the kinase insert domain of the receptor. To assess the role of Shb in PDGF-mediated signaling, we have overexpressed wild-type Shb or Shb carrying a mutation (R522K) which renders the SH2 domain inactive, in Patch mouse (PhB) fibroblasts expressing both PDGF receptors (PhB/Ralpha). Overexpression of wild-type Shb, but not the R522K Shb mutant, affected PDGF-mediated reorganization of the cytoskeleton by decreasing membrane ruffle formation and stimulating the generation of filopodia relative the parental control cells. In addition, the PDGF-induced receptor-associated phosphatidylinositol 3'-kinase activity and phosphorylation of Akt was similar in both PhB/Ralpha/Shb and PhB/Ralpha/ShbR522K cells compared with the parental control, whereas the activation of Rac in response to PDGF-BB was diminished only in the PhB/Ralpha/Shb cells. We conclude that Shb plays a role in PDGF-dependent regulation of certain cytoskeletal changes by modulating the ability of PDGF to activate Rac.
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Affiliation(s)
- R Hooshmand-Rad
- Ludwig Institute for Cancer Research, Biomedical Center, Uppsala, S-751 24, Sweden
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34
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Wang YZ, Wharton W, Garcia R, Kraker A, Jove R, Pledger WJ. Activation of Stat3 preassembled with platelet-derived growth factor beta receptors requires Src kinase activity. Oncogene 2000; 19:2075-85. [PMID: 10815799 DOI: 10.1038/sj.onc.1203548] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Members of the STAT family of transcriptional regulators modulate the expression of a variety of gene products that promote cell proliferation, survival and transformation. Although initially identified as mediators of cytokine signaling, the STAT proteins are also activated by, and thus may contribute to the actions of, polypeptide growth factors. To define the mechanism by which these factors activate STATs, we examined the process of Stat3 activation in Balb/c-3T3 fibroblasts treated with platelet-derived growth factor (PDGF). As STATs are activated by tyrosine phosphorylation, and as PDGF receptors are ligand-activated tyrosine kinases, we considered the possibility that Stat3 interacts with and is phosphorylated by PDGF receptors. We find that Stat3 associates with PDGF beta receptors in both the presence and, surprisingly, the absence of PDGF. Moreover, Stat3 was phosphorylated on tyrosine in PDGF beta receptor immunoprecipitates of PDGF-treated but not untreated cells. Although required, receptor activation was insufficient for Stat3 activation. When added to cells in combination with a pharmacologic agent (PD180970) that specifically inhibits the activity of Src family tyrosine kinases, PDGF did not activate Stat3 as monitored by electrophoretic mobility shift assay. PD180970 did not affect MAPK activation by PDGF or the JAK-dependent activation of Stat3 by interleukin-6. The necessity of Src activity for Stat3 activation by PDGF was further evidenced by data showing the presence of Src in complexes containing both Stat3 and PDGF beta receptors in PDGF-treated cells. These results suggest a novel mechanism of STAT activation in which inactive Stat3 pre-assembles with inactive PDGF receptors, and in response to ligand binding and in a manner dependent on Src kinase activity, is rapidly phosphorylated and activated. Additional data demonstrate that Src kinase activity is also required for PDGF stimulation of DNA synthesis in density-arrested cells.
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Affiliation(s)
- Y Z Wang
- Molecular Oncology, Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA
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35
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Jazayeri A, McGee J, Shimamura T, Cross SB, Bejcek BE. SHP-2 can suppress transformation induced by platelet-derived growth factor. Exp Cell Res 2000; 254:197-203. [PMID: 10640417 DOI: 10.1006/excr.1999.4741] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signaling by either the type alpha or type beta receptors of platelet-derived growth factor occurs by phosphorylation of at least 10 intra-cytoplasmic tyrosine residues and their subsequent association of secondary signaling molecules with Src homology 2 (SH2) domains. Although the role of several of these secondary signaling molecules in mitogenesis has become increasingly clear, their roles in morphological transformation are not as well defined. Here we present evidence that the SHP-2 phosphatase which associates with Tyr 1009 of the type beta receptor and Tyr 720 of the type alpha receptor may suppress transformation induced by the PDGF B chain. Cotransfection of a dominant negative mutant of the SHP-2 gene and the PDGF B chain gene into mouse fibroblasts that only poorly formed foci with the PDGF B chain alone resulted in larger and more prominent foci. Furthermore, introduction of a wild-type copy of the SHP-2 gene into a tumor cell line, U-87MG, which relies on PDGF expression to form foci in vitro, caused a reversion of phenotype.
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Affiliation(s)
- A Jazayeri
- Wayne State University, Detroit, Michigan 48202, USA
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36
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Bernard A, Kazlauskas A. Phosphospecific antibodies reveal temporal regulation of platelet-derived growth factor beta receptor signaling. Exp Cell Res 1999; 253:704-12. [PMID: 10585294 DOI: 10.1006/excr.1999.4715] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The platelet-derived growth factor beta receptor (betaPDGFR) is a receptor tyrosine kinase involved in multiple aspects of cell growth and differentiation. Upon activation, betaPDGFR is phosphorylated at up to nine different tyrosine residues. Phosphorylation of the receptor results in at least two different outcomes: recruitment of signaling molecules and activation of intrinsic receptor kinase activity. In order to evaluate the phosphorylation state of the receptor, phosphospecific antibodies were generated against peptides encompassing betaPDGFR phospho-Y751, phospho-Y771, or phospho-Y857. When phosphorylated, these sites enable the receptor to recruit signaling molecules PI3K or RasGAP, or enhance the receptor's kinase activity, respectively. We found that receptors phosphorylated at Y751, Y771, and Y857 display distinct temporal and spatial distribution by immunofluorescence. Subsequent biochemical studies revealed that receptor function corresponding to each of the phosphorylated sites was regulated as a function of time. Within the first 10 min, PDGF enhanced the receptor's kinase activity and initiated recruitment of PI3K and RasGAP. After prolonged exposure to PDGF, PI3K binding persisted to approximately 85% of the amount bound at 10 min, whereas binding of RasGAP and the exogenous kinase activity of the receptor diminished to less than 15% of the levels displayed at 10 min. We conclude that the phosphorylation state of the receptor, as well as its signaling capacity, is dynamic and changes as cells are continuously exposed to PDGF.
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Affiliation(s)
- A Bernard
- Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, Massachusetts 02114, USA
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37
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Rosenkranz S, DeMali KA, Gelderloos JA, Bazenet C, Kazlauskas A. Identification of the Receptor-associated Signaling Enzymes That Are Required for Platelet-derived Growth Factor-AA-dependent Chemotaxis and DNA Synthesis. J Biol Chem 1999; 274:28335-43. [PMID: 10497192 DOI: 10.1074/jbc.274.40.28335] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the platelet-derived growth factor (PDGF) alpha receptor (alphaPDGFR) leads to cell migration and DNA synthesis. These events are preceded by the ligand-induced tyrosine phosphorylation of the receptor and its association with SH2-containing signaling enzymes including Src family members (Src), the phosphotyrosine phosphatase SHP-2, phosphatidylinositol 3-kinase (PI3K), and phospholipase C-gamma1 (PLCgamma). In this study, we sought to systematically evaluate the relative roles of the signaling enzymes that are recruited to the alphaPDGFR for DNA synthesis and cell migration. Our approach was to generate and characterize tyrosine to phenylalanine alphaPDGFR mutants that failed to associate with one or more of the above listed signaling enzymes. In a 3T3-like cell line (Ph cells), PDGF-dependent DNA synthesis was strictly dependent on only one of the receptor-associated proteins, PI3K. In contrast, multiple signaling enzymes were required for maximal chemotaxis, as receptors unable to associate with either Src, PI3K, or PLCgamma initiated chemotaxis to 4, 47, or 56% of the wild-type level, respectively. Furthermore, coexpression of mutant receptors revealed that these signaling enzymes do not need to be on the same receptor for a cell to respond chemotactically to PDGF. We conclude that for the alphaPDGFR, PI3K plays a major role in initiating DNA synthesis, whereas PI3K, PLCgamma, and especially Src are required for chemotaxis.
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Affiliation(s)
- S Rosenkranz
- Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114, USA
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38
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Miyake S, Mullane-Robinson KP, Lill NL, Douillard P, Band H. Cbl-mediated negative regulation of platelet-derived growth factor receptor-dependent cell proliferation. A critical role for Cbl tyrosine kinase-binding domain. J Biol Chem 1999; 274:16619-28. [PMID: 10347229 DOI: 10.1074/jbc.274.23.16619] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Cbl proto-oncogene product has emerged as a novel negative regulator of receptor and non-receptor tyrosine kinases. Our previous observations that Cbl overexpression in NIH3T3 cells enhanced the ubiquitination and degradation of the platelet-derived growth factor receptor-alpha (PDGFRalpha) and that the expression of oncogenic Cbl mutants up-regulated the PDGFRalpha signaling machinery strongly suggested that Cbl negatively regulates PDGFRalpha signaling. Here, we show that, similar to PDGFRalpha, selective stimulation of PDGFRbeta induces Cbl phosphorylation, and its physical association with the receptor. Overexpression of wild type Cbl in NIH3T3 cells led to an enhancement of the ligand-dependent ubiquitination and subsequent degradation of the PDGFRbeta, as observed with PDGFRalpha. We show that Cbl-dependent negative regulation of PDGFRalpha and beta results in a reduction of PDGF-induced cell proliferation and protection against apoptosis. A point mutation (G306E) that inactivates the tyrosine kinase binding domain in the N-terminal transforming region of Cbl compromised the PDGF-inducible tyrosine phosphorylation of Cbl although this mutant could still associate with the PDGFR. More importantly, the G306E mutation abrogated the ability of Cbl to enhance the ligand-induced ubiquitination and degradation of the PDGFR and to inhibit the PDGF-dependent cell proliferation and protection from apoptosis. These results demonstrate that Cbl can negatively regulate PDGFR-dependent biological responses and that this function requires the conserved tyrosine kinase binding domain of Cbl.
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Affiliation(s)
- S Miyake
- Lymphocyte Biology Section, Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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39
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McTigue MA, Wickersham JA, Pinko C, Showalter RE, Parast CV, Tempczyk-Russell A, Gehring MR, Mroczkowski B, Kan CC, Villafranca JE, Appelt K. Crystal structure of the kinase domain of human vascular endothelial growth factor receptor 2: a key enzyme in angiogenesis. Structure 1999; 7:319-30. [PMID: 10368301 DOI: 10.1016/s0969-2126(99)80042-2] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND Angiogenesis is involved in tumor growth, macular degeneration, retinopathy and other diseases. Vascular endothelial growth factor (VEGF) stimulates angiogenesis by binding to specific receptors (VEGFRs) on the surface of vascular endothelial cells. VEGFRs are receptor tyrosine kinases that, like the platelet-derived growth factor receptors (PDGFRs), contain a large insert within the kinase domain. RESULTS We report here the generation, kinetic characterization, and 2.4 A crystal structure of the catalytic kinase domain of VEGF receptor 2 (VEGFR2). This protein construct, which lacks 50 central residues of the 68-residue kinase insert domain (KID), has comparable kinase activity to constructs containing the entire KID. The crystal structure, determined in an unliganded phosphorylated state, reveals an overall fold and catalytic residue positions similar to those observed in other tyrosine-kinase structures. The kinase activation loop, autophosphorylated on Y1059 prior to crystallization, is mostly disordered; however, a portion of it occupies a position inhibitory to substrate binding. The ends of the KID form a beta-like structure, not observed in other known tyrosine kinase structures, that packs near to the kinase C terminus. CONCLUSIONS The majority of the VEGFR2 KID residues are not necessary for kinase activity. The unique structure observed for the ends of the KID may also occur in other PDGFR family members and may serve to properly orient the KID for signal transduction. This VEGFR2 kinase structure provides a target for design of selective anti-angiogenic therapeutic agents.
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MESH Headings
- Adenosine Triphosphate/metabolism
- Amino Acid Sequence
- Binding Sites
- Catalytic Domain
- Crystallography, X-Ray
- Growth Substances/chemistry
- Humans
- Kinetics
- Models, Molecular
- Molecular Sequence Data
- Multigene Family
- Mutagenesis, Site-Directed
- Neovascularization, Physiologic
- Peptide Fragments/chemistry
- Protein Conformation
- Protein Folding
- Protein Structure, Secondary
- Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/physiology
- Receptors, Growth Factor/chemistry
- Receptors, Growth Factor/genetics
- Receptors, Growth Factor/physiology
- Receptors, Vascular Endothelial Growth Factor
- Recombinant Fusion Proteins/chemistry
- Sequence Alignment
- Sequence Homology, Amino Acid
- Structure-Activity Relationship
- Substrate Specificity
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Affiliation(s)
- M A McTigue
- Agouron Pharmaceuticals, 3565 General Atomics Court, San Diego, CA 92121, USA.
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40
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Rosenkranz S, Kazlauskas A. Evidence for distinct signaling properties and biological responses induced by the PDGF receptor alpha and beta subtypes. Growth Factors 1999; 16:201-16. [PMID: 10372961 DOI: 10.3109/08977199909002130] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Platelet-derived growth factor (PDGF) acts as a potent mitogen, chemoattractant and survival factor for mesenchymal cells. In addition to its importance in mammalian development, PDGF plays a critical role in physiological repair mechanisms and in the pathogenesis of various proliferative diseases. The biological effects of PDGF are initiated via two related receptor tyrosine kinases, termed alpha and betaPDGF receptors. Recent observations provide increasing evidence for distinct roles of the two PDGF receptor subtypes in both embryogenesis and disease formation. Moreover, characterization of the signal relay mechanisms indicates, that the alpha and betaPDGF receptors are not identical in their ability to bind intracellular effector molecules. Furthermore, the two PDGF receptors initiate overlapping, yet distinct signal transduction pathways. These differences may account for some of the variabilities in biological responses resulting from activation of these two receptors.
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Affiliation(s)
- S Rosenkranz
- The Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA
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41
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Hu Y, Böck G, Wick G, Xu Q. Activation of PDGF receptor alpha in vascular smooth muscle cells by mechanical stress. FASEB J 1998; 12:1135-42. [PMID: 9737716 DOI: 10.1096/fasebj.12.12.1135] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypertension increases mechanical force on the arterial wall by as much as 30%, resulting in marked alterations in signal transductions and gene expression in vascular smooth muscle cells (VSMCs) that contribute to matrix protein synthesis, cell proliferation, and differentiation. How the mechanical stimuli are converted into a biological signal in cells has yet to be studied. We investigated the role of both cyclic strain and shear stresses in initiating the cellular signaling on cultured VSMCs and found that mechanical forces evoked activation of mitogen-activated protein kinases, followed by enhanced DNA binding activity of transcription factor AP-1. Physical forces rapidly induced phosphorylation of platelet-derived growth factor receptor (PDGFR) alpha, an activated state. When GRB2, an adapter protein, was immunoprecipitated from treated VSMCs followed by Western blot analysis with anti-phosphotyrosine, -PDGFR alpha, and -GRB2 antibodies, respectively, phosphotyrosine positive staining was observed on PDGFR alpha bands of the same blot in stretch-stressed VSMCs, supporting the mechanical stress-induced activation of PDGFR alpha. Conditioned medium from stretch-stressed VSMCs did not result in PDGFR alpha phosphorylation, and antibodies binding to all forms of PDGFs did not block stress-induced PDGFR alpha activation. Thus, mechanical stresses may directly perturb the cell surface or alter receptor conformation, thereby initiating signaling pathways normally used by growth factors.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Aorta
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cells, Cultured
- GRB2 Adaptor Protein
- Kinetics
- Mitogen-Activated Protein Kinase 1
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/physiology
- Phosphorylation
- Platelet-Derived Growth Factor/pharmacology
- Platelet-Derived Growth Factor/physiology
- Proteins/metabolism
- Rats
- Receptor, Platelet-Derived Growth Factor alpha
- Receptors, Platelet-Derived Growth Factor/isolation & purification
- Receptors, Platelet-Derived Growth Factor/metabolism
- Signal Transduction
- Stress, Mechanical
- Time Factors
- Transcription Factor AP-1/metabolism
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Affiliation(s)
- Y Hu
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck
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42
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Heldin CH, Ostman A, Rönnstrand L. Signal transduction via platelet-derived growth factor receptors. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1378:F79-113. [PMID: 9739761 DOI: 10.1016/s0304-419x(98)00015-8] [Citation(s) in RCA: 273] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Platelet-derived growth factor (PDGF) exerts its stimulatory effects on cell growth and motility by binding to two related protein tyrosine kinase receptors. Ligand binding induces receptor dimerization and autophosphorylation, allowing binding and activation of cytoplasmic SH2-domain containing signal transduction molecules. Thereby, a number of different signaling pathways are initiated leading to cell growth, actin reorganization migration and differentiation. Recent observations suggest that extensive cross-talk occurs between different signaling pathways, and that stimulatory signals are modulated by inhibitory signals arising in parallel.
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Affiliation(s)
- C H Heldin
- Ludwig Institute for Cancer Research, Biomedical Center, Uppsala, Sweden
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43
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Nakamura K, Cambier JC. B Cell Antigen Receptor (BCR)-Mediated Formation of a SHP-2-pp120 Complex and Its Inhibition by FeγRIIB1-BCR Coligation. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.2.684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Accumulating evidence indicates that the Src homology 2-containing tyrosine phosphatase 2 (SHP-2) plays an important role in signal transduction through receptor tyrosine kinase and cytokine receptors. In most models, SHP-2 appears to be a positive mediator of signaling. However, coligation of FcγRIIB1 with B cell Ag receptors (BCR) inhibits BCR-mediated signaling by a mechanism that may involve recruitment of phosphatases SHP-1, SHP-2, and the SH2 containing inositol 5′phosphatase (SHIP) to the phosphorylated FcγRIIB1 immunoreceptor tyrosine-based inhibitory motif. The role of SHP-2 in BCR-mediated cell activation and in FcγRIIB1-mediated inhibitory signaling is unclear. In this study we assessed the association of SHP-2 with phosphotyrosine-containing cellular protein(s) before and after stimulation through these receptors. BCR stimulation induced the association of SHP-2 with a single major tyrosyl-phosphorylated molecule (pp120) that had an apparent molecular mass of 120 kDa. Coligation of FcγRIIB1 with BCR led to a rapid decrease in SHP-2 association with pp120. Analysis of the subcellular localization of pp120 showed that the complex of SHP-2 and tyrosyl-phosphorylated p120 occurs predominantly in the cytosol. Furthermore, the binding of the two molecules was mediated by the interaction of tyrosyl-phosphorylated p120 with the SHP-2 N-terminal SH2 domain. These findings indicate that SHP-2 and pp120 function in BCR signaling, and this function may be inhibited by FcγRIIB1 signaling.
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Affiliation(s)
- Kazuhiro Nakamura
- Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, and Department of Immunology, University of Colorado Health Science Center, Denver, CO 80206
| | - John C. Cambier
- Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, and Department of Immunology, University of Colorado Health Science Center, Denver, CO 80206
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44
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Miyake S, Lupher ML, Druker B, Band H. The tyrosine kinase regulator Cbl enhances the ubiquitination and degradation of the platelet-derived growth factor receptor alpha. Proc Natl Acad Sci U S A 1998; 95:7927-32. [PMID: 9653117 PMCID: PMC20906 DOI: 10.1073/pnas.95.14.7927] [Citation(s) in RCA: 211] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/1998] [Accepted: 05/06/1998] [Indexed: 02/08/2023] Open
Abstract
The Cbl protooncogene product has emerged as a negative regulator of receptor and nonreceptor tyrosine kinases. We recently demonstrated that oncogenic Cbl mutants upregulate the endogenous tyrosine kinase signaling machinery when expressed in the NIH 3T3 cells, and identified the platelet-derived growth factor receptor-alpha (PDGFRalpha) as one of the tyrosine kinases targeted by these oncogenes. These findings suggested a role for the normal Cbl protein in negative regulation of the PDGFRalpha. However, the mechanism of such negative regulation remained to be determined. Here we show that overexpression of the wild-type Cbl enhances the ligand-induced ubiquitination of the PDGFRalpha. Concomitantly, the PDGFRalpha in Cbl-overexpressing cells undergoes a faster ligand-induced degradation compared with that in the control cells. These results identify a role for Cbl in the regulation of ligand-induced ubiquitination and degradation of receptor tyrosine kinases and suggest one potential mechanism for evolutionarily conserved negative regulatory influence of Cbl on tyrosine kinases.
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Affiliation(s)
- S Miyake
- Lymphocyte Biology Section, Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Gelderloos JA, Rosenkranz S, Bazenet C, Kazlauskas A. A role for Src in signal relay by the platelet-derived growth factor alpha receptor. J Biol Chem 1998; 273:5908-15. [PMID: 9488729 DOI: 10.1074/jbc.273.10.5908] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have shown that Src is required for platelet-derived growth factor (PDGF)-dependent cell cycle progression in fibroblasts. Since fibroblasts usually express both PDGF receptors (PDGFRs), these findings suggested that Src was mandatory for signal relay by both the alpha and betaPDGFRs. In this study, we have focused on the role of Src in signal relay by the alphaPDGFR. In response to stimulation with PDGF-AA, which selectively engages the alphaPDGFR, Src family members (Src) associated with the alphaPDGFR and Src kinase were activated. A mutant receptor, in which tyrosines 572 and 574 were replaced with phenylalanine (F72/74), failed to efficiently associate with Src or activate Src. The wild type (WT) and F72/74 receptors induced the expression of c-myc and c-fos to comparable levels. Furthermore, an equivalent extent of PDGF-dependent soft agar growth was observed in cells expressing the WT or the F72/74 alphaPDGFR. Comparing the ability of these two receptors to initiate tyrosine phosphorylation of signaling molecules indicated that both receptors mediated phosphorylation of the receptor itself, phospholipase Cgamma 1, and SHP-2 to similar levels. In contrast, the F72/74 receptor triggered phosphorylation of Shc to 1 and 20% of the WT levels for the 55- and 46-kDa Shc isoforms, respectively. These findings indicate that after exposure of cells to PDGF-AA, Src stably associates with the alphaPDGFR, and Src activity is increased. Furthermore, Src is required for the PDGF-dependent phosphorylation of signaling molecules such as Shc. Finally, activation of Src during the G0/G1 transition does not appear to be required for latter cell cycle events such as induction of c-myc or cell proliferation.
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Affiliation(s)
- J A Gelderloos
- The Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114, USA
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Hooshmand-Rad R, Yokote K, Heldin CH, Claesson-Welsh L. PDGF alpha-receptor mediated cellular responses are not dependent on Src family kinases in endothelial cells. J Cell Sci 1998; 111 ( Pt 5):607-14. [PMID: 9454734 DOI: 10.1242/jcs.111.5.607] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two novel autophosphorylation sites in the juxtamembrane region of the PDGF alpha-receptor, Tyr-572 and Tyr-574, were identified. A Y572/574F mutant PDGF (alpha)-receptor was generated and stably expressed in porcine aortic endothelial cells. In contrast to the wild-type receptor, the mutant receptor was unable to associate with or activate Src family tyrosine kinases. Tyrosine phosphorylated synthetic peptides representing the juxtamembrane sequence of the receptor dose-dependently inhibited the binding of Src family tyrosine kinases to the autophosphorylated PDGF alpha-receptor. The mutant receptor showed similar PDGF-induced kinase activity and ability to mediate mitogenicity, actin reorganization and chemotaxis as the wild-type receptor. Thus activation of Src family kinases by the PDGF alpha-receptor is not essential for PDGF-induced mitogenicity or actin reorganization.
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Affiliation(s)
- R Hooshmand-Rad
- Ludwig Institute for Cancer Research, Box 595, Biomedical Center, S-751 24 Uppsala, Sweden
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Montmayeur JP, Valius M, Vandenheede J, Kazlauskas A. The platelet-derived growth factor beta receptor triggers multiple cytoplasmic signaling cascades that arrive at the nucleus as distinguishable inputs. J Biol Chem 1997; 272:32670-8. [PMID: 9405485 DOI: 10.1074/jbc.272.51.32670] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Stimulation of the platelet-derived growth factor beta receptor (betaPDGFR) activates enzymes such as phosphatidylinositol 3-kinase (PI3K) and phospholipase Cgamma1 (PLCgamma), which ultimately initiate nuclear responses such as enhanced expression of immediate early genes. In an attempt to compare the signaling cascades initiated by PI3K and PLCgamma, we examined the activation of a panel of immediate early genes by betaPDGFR mutants, which preferentially engage PI3K or PLCgamma. When expressed in A431 cells, the wild type receptor and to a lesser extent the mutant receptor that associates with PLCgamma (Y1021) was able to up-regulate c-fos, junB, and KC mRNA expression. In contrast, the receptor mutant that engages PI3K (Y740/51) poorly stimulated c-fos mRNA expression and did not significantly stimulate expression of either JunB or KC. Receptor mutants that did not associate with either PI3K or PLCgamma were dramatically compromised or unable to increase expression of any of these immediate early genes. The differential ability of the Y1021 and Y740/51 receptors to activate c-fos correlated well with an apparent difference in their ability to engage distinct protein kinase C family members. However there did appear to be a degree of redundancy in the cytoplasmic signaling pathways initiated by PI3K and PLCgamma, since both the Y1021 and Y740/51 receptors were able to activate an AP-1-responsive element. We conclude that recruitment of signal relay enzymes to the betaPDGFR is necessary for PDGF-dependent activation of at least some immediate early genes. In addition, whereas the betaPDGFR activates multiple signaling enzymes capable of activating the same nuclear response (activation of c-fos), these signaling cascades do not appear to converge in the cytoplasm but arrive at the nucleus as distinguishable inputs.
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Affiliation(s)
- J P Montmayeur
- Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114, USA
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Wright JH, Drueckes P, Bartoe J, Zhao Z, Shen SH, Krebs EG. A role for the SHP-2 tyrosine phosphatase in nerve growth-induced PC12 cell differentiation. Mol Biol Cell 1997; 8:1575-85. [PMID: 9285826 PMCID: PMC276177 DOI: 10.1091/mbc.8.8.1575] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
SHP-1 and SHP-2 are intracellular protein tyrosine phosphatases containing two adjacent src homology 2 domains that target these phosphatases to cell surface receptor signaling complexes and play a role in receptor signal transduction. In this report the PC12 cell system was used to investigate the potential roles of SHP-1 and SHP-2 in the induction of neuronal differentiation by nerve growth factor (NGF). By using neurite outgrowth as a marker for differentiation, the effects of transfected constructs of SHP-1 and SHP-2 were assessed. Overexpression of a catalytically inactive SHP-2, but not a catalytically inactive SHP-1, blocked NGF-stimulated neurite outgrowth. The mitogen-activated protein kinase (MAPK) signaling cascade is important for the morphological differentiation in PC12 cells, and both SHP-1 and SHP-2 have been implicated to act upstream of MAPK in other receptor signaling systems. A positive role for SHP-2 but not SHP-1 in the activation of MAPK by NGF was demonstrated by introduction of the SHP-2 phosphatase mutants along with hemagglutinin-tagged MAPK. Coexpression studies with the SHP-2 mutant along with mutant forms of MAPK kinase suggested that SHP-2 functions upstream of MAPK kinase and MAPK in NGF-induced neurite outgrowth.
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Affiliation(s)
- J H Wright
- Department of Pharmacology, University of Washington, Seattle 98195, USA
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