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Bradley D, Garand C, Belda H, Gagnon-Arsenault I, Treeck M, Elowe S, Landry CR. The substrate quality of CK2 target sites has a determinant role on their function and evolution. Cell Syst 2024; 15:544-562.e8. [PMID: 38861992 DOI: 10.1016/j.cels.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 02/29/2024] [Accepted: 05/20/2024] [Indexed: 06/13/2024]
Abstract
Most biological processes are regulated by signaling modules that bind to short linear motifs. For protein kinases, substrates may have full or only partial matches to the kinase recognition motif, a property known as "substrate quality." However, it is not clear whether differences in substrate quality represent neutral variation or if they have functional consequences. We examine this question for the kinase CK2, which has many fundamental functions. We show that optimal CK2 sites are phosphorylated at maximal stoichiometries and found in many conditions, whereas minimal substrates are more weakly phosphorylated and have regulatory functions. Optimal CK2 sites tend to be more conserved, and substrate quality is often tuned by selection. For intermediate sites, increases or decreases in substrate quality may be deleterious, as we demonstrate for a CK2 substrate at the kinetochore. The results together suggest a strong role for substrate quality in phosphosite function and evolution. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- David Bradley
- Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec City, QC G1V 0A6, Canada; PROTEO, Le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec City, QC G1V 0A6, Canada; Centre de Recherche sur les Données Massives (CRDM), Université Laval, Québec City, QC G1V 0A6, Canada; Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada.
| | - Chantal Garand
- PROTEO, Le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec City, QC G1V 0A6, Canada; Axe de Reproduction, Santé de la mère et de l'enfant, CHU de Québec, Université Laval, Québec City, QC, Canada
| | - Hugo Belda
- Signalling in Host-Pathogen Interaction Laboratory, The Francis Crick Institute, London NW11AT, UK
| | - Isabelle Gagnon-Arsenault
- Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec City, QC G1V 0A6, Canada; PROTEO, Le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec City, QC G1V 0A6, Canada; Centre de Recherche sur les Données Massives (CRDM), Université Laval, Québec City, QC G1V 0A6, Canada; Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada
| | - Moritz Treeck
- Signalling in Host-Pathogen Interaction Laboratory, The Francis Crick Institute, London NW11AT, UK; Cell Biology of Host-Pathogen Interaction Laboratory, The Gulbenkian Institute of Science, Oeiras 2780-156, Portugal
| | - Sabine Elowe
- PROTEO, Le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec City, QC G1V 0A6, Canada; Axe de Reproduction, Santé de la mère et de l'enfant, CHU de Québec, Université Laval, Québec City, QC, Canada; Department of Pediatrics, Faculty of Medicine, Université Laval, Québec City, QC, Canada; Centre de Recherche sur le Cancer, CHU de Québec, Université Laval, Québec City, QC, Canada
| | - Christian R Landry
- Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec City, QC G1V 0A6, Canada; PROTEO, Le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec City, QC G1V 0A6, Canada; Centre de Recherche sur les Données Massives (CRDM), Université Laval, Québec City, QC G1V 0A6, Canada; Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Québec City, QC G1V 0A6, Canada.
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Androutsopoulos G, Styliara I, Zarogianni E, Lazurko N, Valasoulis G, Michail G, Adonakis G. The ErbB Signaling Network and Its Potential Role in Endometrial Cancer. EPIGENOMES 2023; 7:24. [PMID: 37873809 PMCID: PMC10594534 DOI: 10.3390/epigenomes7040024] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/24/2023] [Accepted: 09/26/2023] [Indexed: 10/25/2023] Open
Abstract
Endometrial cancer (EC) is the second most common malignancy of the female reproductive system worldwide. The updated EC classification emphasizes the significant role of various signaling pathways such as PIK3CA-PIK3R1-PTEN and RTK/RAS/β-catenin in EC pathogenesis. Some of these pathways are part of the EGF system signaling network, which becomes hyperactivated by various mechanisms and participates in cancer pathogenesis. In EC, the expression of ErbB receptors is significantly different, compared with the premenopausal and postmenopausal endometrium, mainly because of the increased transcriptional activity of ErbB encoding genes in EC cells. Moreover, there are some differences in ErbB-2 receptor profile among EC subgroups that could be explained by the alterations in pathophysiology and clinical behavior of various EC histologic subtypes. The fact that ErbB-2 receptor expression is more common in aggressive EC histologic subtypes (papillary serous and clear cell) could indicate a future role of ErbB-targeted therapies in well-defined EC subgroups with overexpression of ErbB receptors.
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Affiliation(s)
- Georgios Androutsopoulos
- Gynaecological Oncology Unit, Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece
- Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece; (I.S.); (E.Z.); (N.L.); (G.M.); (G.A.)
| | - Ioanna Styliara
- Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece; (I.S.); (E.Z.); (N.L.); (G.M.); (G.A.)
| | - Evgenia Zarogianni
- Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece; (I.S.); (E.Z.); (N.L.); (G.M.); (G.A.)
| | - Nadia Lazurko
- Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece; (I.S.); (E.Z.); (N.L.); (G.M.); (G.A.)
| | - George Valasoulis
- Department of Obstetrics and Gynaecology, Medical School, University of Thessaly, 41334 Larisa, Greece;
- Hellenic National Public Health Organization—ECDC, 15123 Athens, Greece
| | - Georgios Michail
- Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece; (I.S.); (E.Z.); (N.L.); (G.M.); (G.A.)
| | - Georgios Adonakis
- Department of Obstetrics and Gynaecology, School of Medicine, University of Patras, 26504 Rion, Greece; (I.S.); (E.Z.); (N.L.); (G.M.); (G.A.)
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Abstract
Phospholipase C γ1 (PLCγ1) is a member of the PLC family that functions as signal transducer by hydrolyzing membrane lipid to generate second messengers. The unique protein structure of PLCγ1 confers a critical role as a direct effector of VEGFR2 and signaling mediated by other receptor tyrosine kinases. The distinct vascular phenotypes in PLCγ1-deficient animal models and the gain-of-function mutations of PLCγ1 found in human endothelial cancers point to a major physiological role of PLCγ1 in the endothelial system. In this review, we discuss aspects of physiological and molecular function centering around PLCγ1 in the context of endothelial cells and provide a perspective for future investigation.
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Affiliation(s)
- Dongying Chen
- Yale Cardiovascular Research Center, Departments of Internal Medicine and Cell Biology, Yale University School of Medicine, New Haven, CT 06511, USA
| | - Michael Simons
- Yale Cardiovascular Research Center, Departments of Internal Medicine and Cell Biology, Yale University School of Medicine, New Haven, CT 06511, USA.
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Nami B, Maadi H, Wang Z. Mechanisms Underlying the Action and Synergism of Trastuzumab and Pertuzumab in Targeting HER2-Positive Breast Cancer. Cancers (Basel) 2018; 10:cancers10100342. [PMID: 30241301 PMCID: PMC6210751 DOI: 10.3390/cancers10100342] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/13/2018] [Accepted: 09/18/2018] [Indexed: 02/08/2023] Open
Abstract
Human epidermal growth factor receptor (HER) 2 (HER2) is overexpressed in 20⁻30% of breast cancers. HER2 is a preferred target for treating HER2-positive breast cancer. Trastuzumab and pertuzumab are two HER2-targeted monoclonal antibodies approved by the Food and Drug Administration (FDA) to use as adjuvant therapy in combination with docetaxel to treat metastatic HER2-positive breast cancer. Adding the monoclonal antibodies to treatment regimen has changed the paradigm for treatment of HER2-positive breast cancer. Despite improving outcomes, the percentage of the patients who benefit from the treatment is still low. Continued research and development of novel agents and strategies of drug combinations is needed. A thorough understanding of the molecular mechanisms underlying the action and synergism of trastuzumab and pertuzumab is essential for moving forward to achieve high efficacy in treating HER2-positive breast cancer. This review examined and analyzed findings and hypotheses regarding the action and synergism of trastuzumab and pertuzumab and proposed a model of synergism based on available information.
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Affiliation(s)
- Babak Nami
- Signal Transduction Research Group, Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Hamid Maadi
- Signal Transduction Research Group, Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Zhixiang Wang
- Signal Transduction Research Group, Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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5
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β-Heregulin impairs EGF induced PLC-γ1 signalling in human breast cancer cells. Cell Signal 2018; 52:23-34. [PMID: 30165102 DOI: 10.1016/j.cellsig.2018.08.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/23/2018] [Accepted: 08/26/2018] [Indexed: 11/20/2022]
Abstract
The interplay of ErbB receptor homo- and heterodimers plays a crucial role in the pathology of breast cancer since activated signal transduction cascades coordinate proliferation, survival and migration of cells. EGF and β-Heregulin are well characterised ligands known to induce ErbB homo- and heterodimerisation, which have been associated with disease progression. In the present study, we investigated the impact of both factors on the migration of MDA-NEO and MDA-HER2 human breast cancer cells. MDA-NEO cells are positive for EGFR and HER3, while MDA-HER2 cells express EGFR, HER2 and HER3. Cell migration analysis revealed that β-Heregulin potently impaired EGF induced migration in both cell lines. Western blot studies showed that both ErbB receptor and PLC-γ1 tyrosine phosphorylation levels were diminished in EGF and β-Heregulin co-treated MDA-NEO and MDA-HER2 cells, which was further correlated to a significantly impaired calcium influx. Our data indicate that EGF and HRG may interfere with each other for receptor binding and dimerisation, which ultimately has an impact on signalling outcome.
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Abstract
The ErbB receptor family, also known as the EGF receptor family or type I receptor family, includes the epidermal growth factor (EGF) receptor (EGFR) or ErbB1/Her1, ErbB2/Her2, ErbB3/Her3, and ErbB4/Her4. Among all RTKs, EGFR was the first RTK identified and the first one linked to cancer. Thus, EGFR has also been the most intensively studied among all RTKs. ErbB receptors are activated after homodimerization or heterodimerization. The ErbB family is unique among the various groups of receptor tyrosine kinases (RTKs) in that ErbB3 has impaired kinase activity, while ErbB2 does not have a direct ligand. Therefore, heterodimerization is an important mechanism that allows the activation of all ErbB receptors in response to ligand stimulation. The activated ErbB receptors bind to many signaling proteins and stimulate the activation of many signaling pathways. The specificity and potency of intracellular signaling pathways are determined by positive and negative regulators, the specific composition of activating ligand(s), receptor dimer components, and the diverse range of proteins that associate with the tyrosine phosphorylated C-terminal domain of the ErbB receptors. ErbB receptors are overexpressed or mutated in many cancers, especially in breast cancer, ovarian cancer, and non-small cell lung cancer. The overexpression and overactivation of ErbB receptors are correlated with poor prognosis, drug resistance, cancer metastasis, and lower survival rate. ErbB receptors, especially EGFR and ErbB2 have been the primary choices as targets for developing cancer therapies.
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Affiliation(s)
- Zhixiang Wang
- Signal Transduction Research Group, Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, 835 MSB, 114 St NW, Edmonton, AB, Canada, T6G 2H7.
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7
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Huang Z, Marsiglia WM, Basu Roy U, Rahimi N, Ilghari D, Wang H, Chen H, Gai W, Blais S, Neubert TA, Mansukhani A, Traaseth NJ, Li X, Mohammadi M. Two FGF Receptor Kinase Molecules Act in Concert to Recruit and Transphosphorylate Phospholipase Cγ. Mol Cell 2015; 61:98-110. [PMID: 26687682 DOI: 10.1016/j.molcel.2015.11.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 10/28/2015] [Accepted: 11/05/2015] [Indexed: 11/28/2022]
Abstract
The molecular basis by which receptor tyrosine kinases (RTKs) recruit and phosphorylate Src Homology 2 (SH2) domain-containing substrates has remained elusive. We used X-ray crystallography, NMR spectroscopy, and cell-based assays to demonstrate that recruitment and phosphorylation of Phospholipase Cγ (PLCγ), a prototypical SH2 containing substrate, by FGF receptors (FGFR) entails formation of an allosteric 2:1 FGFR-PLCγ complex. We show that the engagement of pTyr-binding pocket of the cSH2 domain of PLCγ by the phosphorylated tail of an FGFR kinase induces a conformational change at the region past the cSH2 core domain encompassing Tyr-771 and Tyr-783 to facilitate the binding/phosphorylation of these tyrosines by another FGFR kinase in trans. Our data overturn the current paradigm that recruitment and phosphorylation of substrates are carried out by the same RTK monomer in cis and disclose an obligatory role for receptor dimerization in substrate phosphorylation in addition to its canonical role in kinase activation.
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Affiliation(s)
- Zhifeng Huang
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | | | - Upal Basu Roy
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Nader Rahimi
- Department of Pathology and Laboratory of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Dariush Ilghari
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Huiyan Wang
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Huaibin Chen
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Weiming Gai
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Steven Blais
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Thomas A Neubert
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Alka Mansukhani
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | | | - Xiaokun Li
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
| | - Moosa Mohammadi
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA.
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Cho-Clark M, Larco DO, Semsarzadeh NN, Vasta F, Mani SK, Wu TJ. GnRH-(1-5) transactivates EGFR in Ishikawa human endometrial cells via an orphan G protein-coupled receptor. Mol Endocrinol 2013; 28:80-98. [PMID: 24264576 DOI: 10.1210/me.2013-1203] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The decapeptide GnRH is known for its central role in the regulation of the hypothalamo-pituitary-gonadal axis. In addition, it is also known to have local effects within peripheral tissues. The zinc metalloendopeptidase, EC 3.4.24.15 (EP24.15), can cleave GnRH at the Tyr(5)-Gly(6) bond to form the pentapeptide, GnRH-(1-5). The central and peripheral effect of GnRH-(1-5) is different from its parent peptide, GnRH. In the current study, we examined the effect of GnRH-(1-5) on epidermal growth factor receptor (EGFR) phosphorylation and cellular migration. Using the Ishikawa cell line as a model of endometrial cancer, we demonstrate that GnRH-(1-5) stimulates epidermal growth factor release, increases the phosphorylation of EGFR (P < .05) at three tyrosine sites (992, 1045, 1068), and promotes cellular migration. In addition, we also demonstrate that these actions of GnRH-(1-5) are mediated by the orphan G protein-coupled receptor 101 (GPR101). Down-regulation of GPR101 expression blocked the GnRH-(1-5)-mediated release of epidermal growth factor and the subsequent phosphorylation of EGFR and cellular migration. These results suggest that GPR101 is a critical requirement for GnRH-(1-5) transactivation of EGFR in Ishikawa cells.
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Affiliation(s)
- Madelaine Cho-Clark
- Department of Obstetrics and Gynecology (T.J.W., M.C., F.V.) and the Program in Molecular and Cellular Biology (D.O.L., T.J.W.), Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, Maryland 20814; and Departments of Molecular and Cellular Biology and Neuroscience (S.K.M.), Baylor College of Medicine, Houston, Texas 77030
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Xie Z, Jiang Y, Liao EY, Chen Y, Pennypacker SD, Peng J, Chang SM. PIKE mediates EGFR proliferative signaling in squamous cell carcinoma cells. Oncogene 2012; 31:5090-8. [PMID: 22349826 DOI: 10.1038/onc.2012.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/30/2011] [Indexed: 11/08/2022]
Abstract
One of the key drivers for squamous cell carcinoma (SCC) proliferation is activation of the epidermal growth factor receptor (EGFR), a known proto-oncogene. However, the mechanism of EGFR-dependent SCC proliferation remains unclear. Our previous studies indicate that epidermal growth factor (EGF)-induced SCC cell proliferation requires the SH3 domain of phospholipase C-γ1 (PLC-γ1), but not its catalytic activity. The SH3 domain of PLC-γ1 is known to activate the short form of nuclear phosphatidylinositol 3-kinase enhancer (PIKE) that enhances the activity of nuclear class Ia phosphatidylinositol 3-kinase (PI3K) required for proliferation. However, PIKE has been described for more than a decade to be present exclusively in neuronal cells. In the present study, we found that PIKE was highly expressed in malignant human keratinocytes (SCC4 and SCC12B2) but had low expression in normal human keratinocytes. Immunohistochemical analysis showed strong nuclear staining of PIKE in human epidermal and tongue SCC specimens but little staining in the adjacent non-cancerous epithelium. Treatment of SCC4 cells with EGF-induced translocation of PLC-γ1 to the nucleus and binding of PLC-γ1 to the nuclear PIKE. Knockdown of PLC-γ1 or PIKE blocked EGF-induced activation of class Ia PI3K and protein kinase C-ζ and phosphorylation of nucleolin in the nucleus as well as EGF-induced SCC cell proliferation. However, inhibition of the catalytic activity of PLC-γ1 had little effect. These data suggest that PIKE has a critical role in EGF-induced SCC cell proliferation and may function as a proto-oncogene in SCC.
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Affiliation(s)
- Z Xie
- Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
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EGFR: A Master Piece in G1/S Phase Transition of Liver Regeneration. Int J Hepatol 2012; 2012:476910. [PMID: 23050157 PMCID: PMC3461622 DOI: 10.1155/2012/476910] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 07/11/2012] [Indexed: 02/07/2023] Open
Abstract
Unraveling the molecular clues of liver proliferation has become conceivable thanks to the model of two-third hepatectomy. The synchronicity and the well-scheduled aspect of this process allow scientists to slowly decipher this mystery. During this phenomenon, quiescent hepatocytes of the remnant lobes are able to reenter into the cell cycle initiating the G1-S progression synchronously before completing the cell cycle. The major role played by this step of the cell cycle has been emphasized by loss-of-function studies showing a delay or a lack of coordination in the hepatocytes G1-S progression. Two growth factor receptors, c-Met and EGFR, tightly drive this transition. Due to the level of complexity surrounding EGFR signaling, involving numerous ligands, highly controlled regulations and multiple downstream pathways, we chose to focus on the EGFR pathway for this paper. We will first describe the EGFR pathway in its integrity and then address its essential role in the G1/S phase transition for hepatocyte proliferation. Recently, other levels of control have been discovered to monitor this pathway, which will lead us to discuss regulations of the EGFR pathway and highlight the potential effect of misregulations in pathologies.
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Yamaoka T, Frey MR, Dise RS, Bernard JK, Polk DB. Specific epidermal growth factor receptor autophosphorylation sites promote mouse colon epithelial cell chemotaxis and restitution. Am J Physiol Gastrointest Liver Physiol 2011; 301:G368-76. [PMID: 21617115 PMCID: PMC3154598 DOI: 10.1152/ajpgi.00327.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Upon ligand binding, epidermal growth factor (EGF) receptor (R) autophosphorylates on COOH-terminal tyrosines, generating docking sites for signaling partners that stimulate proliferation, restitution, and chemotaxis. Specificity for individual EGFR tyrosines in cellular responses has been hypothesized but not well documented. Here we tested the requirement for particular tyrosines, and associated downstream pathways, in mouse colon epithelial cell chemotactic migration. We compared these requirements to those for the phenotypically distinct restitution (wound healing) migration. Wild-type, Y992/1173F, Y1045F, Y1068F, and Y1086F EGFR constructs were expressed in EGFR(-/-) cells; EGF-induced chemotaxis or restitution were determined by Boyden chamber or modified scratch wound assay, respectively. Pharmacological inhibitors of p38, phospholipase C (PLC), Src, MEK, JNK/SAPK, phosphatidylinositol 3-kinase (PI 3-kinase), and protein kinase C (PKC) were used to block EGF-stimulated signaling. Pathway activation was determined by immunoblot analysis. Unlike wild-type EGFR, Y992/1173F and Y1086F EGFR did not stimulate colon epithelial cell chemotaxis toward EGF; Y1045F and Y1068F EGFR partially stimulated chemotaxis. Only wild-type EGFR promoted colonocyte restitution. Inhibition of p38, PLC, and Src, or Grb2 knockdown, blocked chemotaxis; JNK, PI 3-kinase, and PKC inhibitors or c-Cbl knockdown blocked restitution but not chemotaxis. All four EGFR mutants stimulated downstream signaling in response to EGF, but Y992/1173F EGFR was partially defective in PLCγ activation whereas both Y1068F and Y1086F EGFR failed to activate Src. We conclude that specific EGFR tyrosines play key roles in determining cellular responses to ligand. Chemotaxis and restitution, which have different migration phenotypes and physiological consequences, have overlapping but not identical EGFR signaling requirements.
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Affiliation(s)
- Toshimitsu Yamaoka
- 1Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition and
| | - Mark R. Frey
- 3Department of Pediatrics, Division of Gastroenterology and Nutrition and ,4Department of Biochemistry and Molecular Biology, University of Southern California Keck School of Medicine and The Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, California
| | - Rebecca S. Dise
- 2Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Jessica K. Bernard
- 3Department of Pediatrics, Division of Gastroenterology and Nutrition and
| | - D. Brent Polk
- 1Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition and ,2Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee; and ,3Department of Pediatrics, Division of Gastroenterology and Nutrition and ,4Department of Biochemistry and Molecular Biology, University of Southern California Keck School of Medicine and The Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, California
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Al-Khodor S, Abu Kwaik Y. Triggering Ras signalling by intracellular Francisella tularensis through recruitment of PKCα and βI to the SOS2/GrB2 complex is essential for bacterial proliferation in the cytosol. Cell Microbiol 2011; 12:1604-21. [PMID: 20618341 DOI: 10.1111/j.1462-5822.2010.01494.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Intracellular proliferation of Francisella tularensis is essential for manifestation of the fatal disease tularaemia, and is classified as a category A bioterrorism agent. The F. tularensis-containing phagosome (FCP) matures into a late endosome-like phagosome with limited fusion to lysosomes, followed by rapid bacterial escape into the cytosol. The Francisella pathogenicity island (FPI) encodes a type VI-like secretion system, and the FPI-encoded IglC is essential for evasion of lysosomal fusion and phagosomal escape. Many host signalling events are likely to be modulated by F. tularensis to render the cell permissive for intracellular proliferation but they are not fully understood. Here we show that within 15 min of infection, intracellular F. tularensis ssp. novicida triggers IglC-dependent temporal activation of Ras, but attached extracellular bacteria fail to trigger Ras activation, which has never been shown for other intracellular pathogens. Intracellular F. tularensis ssp. novicida triggers activation of Ras through recruitment of PKCα and PKCβI to the SOS2/GrB2 complex. Silencing of SOS2, GrB2 and PKCα and PKCβI by RNAi has no effect on evasion of lysosomal fusion and bacterial escape into the cytosol but renders the cytosol non-permissive for replication of F. tularensis ssp. novicida. Since Ras activation promotes cell survival, we show that silencing of SOS2, GrB2 and PKCα and βI is associated with rapid early activation of caspase-3 within 8 h post infection. However, silencing of SOS2, GrB2 and PKCα and βI does not affect phosphorylation of Akt or Erk, indicating that activation of the PI3K/Akt and the Erk signalling cascade are independent of the F. tularensis-triggered Ras activation. We conclude that intracellular F. tularensis ssp. novicida triggers temporal and early activation of Ras through the SOS2/GrB2/PKCα/PKCβI quaternary complex. Temporal and rapid trigger of Ras signalling by intracellular F. tularensis is essential for intracellular bacterial proliferation within the cytosol, and this is associated with downregulation of early caspase-3 activation.
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Affiliation(s)
- Souhaila Al-Khodor
- Department of Microbiology and Immunology, College of Medicine, Department of Biology, University of Louisville, Louisville, KY 40202, USA
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Xie Z, Chen Y, Liao EY, Jiang Y, Liu FY, Pennypacker SD. Phospholipase C-gamma1 is required for the epidermal growth factor receptor-induced squamous cell carcinoma cell mitogenesis. Biochem Biophys Res Commun 2010; 397:296-300. [PMID: 20510673 DOI: 10.1016/j.bbrc.2010.05.103] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 05/21/2010] [Indexed: 11/17/2022]
Abstract
The epidermal growth factor receptor (EGFR) is a key driver in the process of squamous cell carcinoma (SCC) cell mitogenesis. Phospholipase C-gamma1 (PLC-gamma1) is a downstream target of EGFR signaling, but the role and necessity of PLC-gamma1 in EGFR-induced cell mitogenesis remain unclear. In the present study, we report an elevated expression of PLC-gamma1 in human SCC biopsies relative to adjacent normal epidermis, and in human SCC cell lines compared to normal human keratinocytes. EGFR-induced SCC cell mitogenesis was blocked by small interfering RNA knockdown of PLC-gamma1. However, inhibition of the catalytic activity of phospholipase C had no effect on EGFR-induced SCC cell mitogenesis. In response to the EGFR ligand epidermal growth factor (EGF), PLC-gamma1 was translocated not only to the plasma membrane but also to the nucleus. These data suggest that PLC-gamma1 is required for EGFR-induced SCC cell mitogenesis and the mitogenic function of PLC-gamma1 is independent of its lipase activity.
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Affiliation(s)
- Zhongjian Xie
- Endocrine Unit, Veterans Affairs Medical Center, Northern California Institute for Research and Education, University of California, San Francisco, CA 94121, USA.
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Poulin B, Sekiya F, Rhee SG. Intramolecular interaction between phosphorylated tyrosine-783 and the C-terminal Src homology 2 domain activates phospholipase C-gamma1. Proc Natl Acad Sci U S A 2005; 102:4276-81. [PMID: 15764700 PMCID: PMC555506 DOI: 10.1073/pnas.0409590102] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phospholipase C-gamma1 (PLC-gamma1) contains two tandem Src homology 2 (SH2) domains. The NH(2)-terminal SH2 domain has been known to mediate the binding of PLC-gamma1 to receptor protein tyrosine kinases, which then activate PLC-gamma1 via phosphorylation at Y783. We now show that the phosphorylated Y783 residue (pY783) associates with the COOH-terminal SH2 domain [SH2(C)] within the same molecule of PLC-gamma1. The specificity of this intramolecular interaction is demonstrated in several ways. The mutation of SH2(C), but not of the NH(2)-terminal SH2 domain, exposes pY783 and makes it available for binding by anti-pY783 antibodies, for intermolecular association with a GST fusion protein containing the tandem SH2 domains of PLC-gamma1 and for dephosphorylation by phosphatases. The intramolecular interaction between pY783 and SH2(C) induces a rearrangement of surface charge such that PLC-gamma1 molecules phosphorylated at Y783 are retained more strongly by heparin resins than are unphosphorylated molecules. Finally, the intramolecular interaction of pY783 with SH2(C) results in activation of phospholipase activity. Our results thus clarify the molecular mechanism of PLC-gamma1 activation, revealing the specific function of pY783 and the distinct roles of the two SH2 domains in this process.
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Affiliation(s)
- Benoit Poulin
- Laboratory of Cell Signaling, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8015, USA
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Fan YX, Wong L, Deb TB, Johnson GR. Ligand regulates epidermal growth factor receptor kinase specificity: activation increases preference for GAB1 and SHC versus autophosphorylation sites. J Biol Chem 2004; 279:38143-50. [PMID: 15231819 DOI: 10.1074/jbc.m405760200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) kinase catalyzes phosphorylation of tyrosines in its C terminus and in other cellular targets upon epidermal growth factor (EGF) stimulation. Here, by using peptides derived from EGFR autophosphorylation sites and cellular substrates, we tested the hypothesis that ligand may function to regulate EGFR kinase specificity by modulating the binding affinity of peptide sequences to the active site. Measurement of the steady-state kinetic parameters, K(m) and k(cat), revealed that EGF did not affect the binding of EGFR peptides but increased the binding affinity for peptides corresponding to the major EGFR-mediated phosphorylation sites of the adaptor proteins Gab1 (Tyr-627) and Shc (Tyr-317), and for peptides containing the previously identified optimal EGFR kinase substrate sequence EEEEYFELV (3-7-fold). Conversely, EGF stimulation increased k(cat) approximately 5-fold for all peptides. Thus, ligand changed the relative preference of the EGFR kinase for substrates as evidenced by EGF increases of approximately 5-fold in the specificity constants (k(cat)/K(m)) for EGFR peptides, whereas approximately 15-40-fold increases were observed for other peptides, such as Gab1 Tyr-627. Furthermore, we demonstrate that EGF (i) increased the binding affinity of EGFR to Gab1 Tyr-627 and Shc Tyr-317 sites in purified GST fusion proteins approximately 4-6-fold, and (ii) EGF significantly enhanced the phosphorylation of these sites, relative to EGFR autophosphorylation, in cell lysates containing the full-length Gab1 and Shc proteins. Analysis of peptides containing amino acid substitutions indicated that residues C-terminal to the target tyrosine were critical for EGF-stimulated increases in substrate binding and regulation of kinase specificity. To our knowledge, this represents the first demonstration that ligand can alter specificity of a receptor kinase toward physiologically relevant targets.
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Affiliation(s)
- Ying-Xin Fan
- Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
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16
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Abstract
In 1986, Pawson's group recognized a region of homology between two oncogenic tyrosine kinases that lay outside the catalytic domain. They termed this the Src homology 2, or SH2, domain. In the ensuing years, SH2 domains have been found in an impressive variety of proteins, as has a second region of homology, inevitably termed SH3. These domains appear to mediate controlled protein-protein interactions. Many proteins that contain SH2 and SH3 domains are involved in signal transduction, suggesting a new paradigm for regulation of intracellular signalling pathways.
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Affiliation(s)
- B J Mayer
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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Chen DB, Davis JS. Epidermal growth factor induces c-fos and c-jun mRNA via Raf-1/MEK1/ERK-dependent and -independent pathways in bovine luteal cells. Mol Cell Endocrinol 2003; 200:141-54. [PMID: 12644307 DOI: 10.1016/s0303-7207(02)00379-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Epidermal growth factor (EGF) modulates the actions of gonadotropins in the corpus luteum. The membrane-associated EGF receptors undergo rapid tyrosine phosphorylation and internalization upon ligand binding in ovarian cells, including luteal cells. However, little is known about the post-receptor signaling events induced by EGF that lead to the transcriptional regulation of EGF-responsive genes in the ovary. The present study was designed to examine in bovine luteal cells (1) activation of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling cascade (Raf/MEK/ERK) by EGF; (2) mRNA expression of AP-1 transcription factors, i.e. c-fos and c-jun, in response to EGF; and (3) the role of ERK in EGF-induced expression of c-fos and c-jun mRNA. Raf-1 and B-Raf, but not A-Raf, were activated by EGF (10 ng/ml) and the pharmacological protein kinase C (PKC) activator phorbol myristate acetate (PMA, 20 nM). Activation of Raf resulted in the phosphorylation and activation of MAPK kinase (MEK1) which subsequently activated ERKs. Treatment with EGF-induced the phosphorylation of both ERK2 and ERK1 in a time and concentration dependent manner. Additionally, activated ERK was found in the nucleus of the cells following treatment with EGF (10 ng/ml) and PMA (PMA, 20 nM) for 5 min. Depletion of PKC by chronic PMA treatment (2.5 microM, 24 h) only partially inhibited the stimulatory effects of EGF on Raf-1, ERK2 and ERK1. These data demonstrate that PKC-dependent and independent-mechanisms are involved in EGF activation of the Raf/MEK/ERK signaling cascade in bovine luteal cells. EGF rapidly and transiently stimulated the expression of c-fos and c-jun mRNA in bovine luteal cells. Maximal induction of c-fos and c-jun mRNA by EGF occurred within 30 min of treatment with 10 ng/ml EGF. Treatment with the MEK1 inhibitor PD098059 (50 microM) abolished EGF-induced ERK activation. However, blocking EGF-induced ERK activation by pretreatment with PD098059 only partially attenuated EGF-induced c-fos and c-jun mRNA expression. Thus, additional pathways are implicated in the regulation of c-fos and c-jun mRNA expression by EGF in bovine luteal cells.
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Affiliation(s)
- Dong-bao Chen
- The Women's Research Institute, Department of Obstetrics and Gynecology, University of Kansas School of Medicine-Wichita, 1010 North Kansas, Wichita 67214, USA.
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18
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Tamás P, Solti Z, Buday L. Membrane-targeting is critical for the phosphorylation of Vav2 by activated EGF receptor. Cell Signal 2001; 13:475-81. [PMID: 11516622 DOI: 10.1016/s0898-6568(01)00172-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Vav2 is a member of the Vav family that serves as guanine nucleotide exchange factors (GEFs) for the Rho family of Ras-related GTPases. Unlike Vav1, whose expression is restricted to cells of hematopoietic origin, Vav2 is broadly expressed. Recently, Vav2 has been identified as a substrate for the EGF receptor. Here, we show that in EGF-treated COS7 cells Vav2 is phosphorylated on tyrosine residues and associates with the EGF receptor. In addition, introducing point mutations into the SH2 domain of green fluorescens protein (GFP)-Vav2 fusion protein leads to the loss of Vav2 tyrosine phosphorylation in response to EGF. To investigate further the mechanism of Vav2 phosphorylation, N-terminal (NT) domain of Vav2 was transiently expressed in COS7 cells as GFP fusion protein. Whereas the NT domain of Vav2 is a preferred substrate for the activated EGF receptor in vitro, we could not detect tyrosine phosphorylation of the GFP-NT construct in EGF-treated cells. However, when the SH2 domain of Vav2 was fused to its NT domain, NT domain proved to be a substrate for the EGF receptor in vivo. These data suggest that membrane-targeting of Vav2 through its SH2 domain is an important event in the phosphorylation and activation of Vav2 in response to EGF.
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Affiliation(s)
- P Tamás
- Department of Medical Chemistry, Semmelweis University Medical School, 9 Puskin Street, 1088, Budapest, Hungary
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19
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Nojiri S, Hoek JB. Suppression of epidermal growth factor-induced phospholipase C activation associated with actin rearrangement in rat hepatocytes in primary culture. Hepatology 2000; 32:947-57. [PMID: 11050044 DOI: 10.1053/jhep.2000.18662] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Hepatocytes maintained in primary culture for periods of 1 to 24 hours exhibited a rapid decline in epidermal growth factor (EGF)-induced activation of phospholipase C (PLC), as was evident in a loss of EGF-induced inositol 1,4,5-trisphosphate (IP(3)) formation and mobilization of Ca(2+) from intracellular Ca(2+) stores. The loss of PLC activation was not the result of a decrease in EGF receptor or phospholipase C-gamma1 (PLCgamma1) protein levels, nor the result of a loss of tyrosine phosphorylation of these proteins, but was associated with a decrease in EGF-induced translocation of PLCgamma1 to the Triton-insoluble fraction, presumably reflecting binding to the actin cytoskeleton. Disruption of F-actin by treatment of cultured hepatocytes with cytochalasin D recovered the EGF-induced IP(3) formation and Ca(2+) mobilization to the same level and with the same dose-response relationship as was obtained in freshly isolated cells. Analysis of PLCgamma1 colocalization with F-actin by confocal microscopy showed that PLCgamma1 was mostly distributed diffusely in the cytosol, both in freshly plated cells and in cells in culture for 24 hours, despite marked differences in actin structures. EGF stimulation caused a modest redistribution of PLCgamma1 and a detectable increase in colocalization with cortical actin structures in freshly plated cells or in cytochalasin D-treated cells, but in cells that had been maintained and spread in culture only a limited PLCgamma1 relocation was detected to specific actin-structure associated with lamellipodia and membrane ruffles. We conclude that actin cytoskeletal structures can exert negative control over PLCgamma1 activity in hepatocytes and the interaction of the enzyme with specific actin structures dissociates PLCgamma1 tyrosine phosphorylation from activation of its enzymatic activity.
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Affiliation(s)
- S Nojiri
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
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20
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Haugh JM, Wells A, Lauffenburger DA. Mathematical modeling of epidermal growth factor receptor signaling through the phospholipase C pathway: Mechanistic insights and predictions for molecular interventions. Biotechnol Bioeng 2000. [DOI: 10.1002/1097-0290(20001020)70:2<225::aid-bit12>3.0.co;2-s] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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21
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DeBell KE, Stoica BA, Verí MC, Di Baldassarre A, Miscia S, Graham LJ, Rellahan BL, Ishiai M, Kurosaki T, Bonvini E. Functional independence and interdependence of the Src homology domains of phospholipase C-gamma1 in B-cell receptor signal transduction. Mol Cell Biol 1999; 19:7388-98. [PMID: 10523627 PMCID: PMC84732 DOI: 10.1128/mcb.19.11.7388] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
B-cell receptor (BCR)-induced activation of phospholipase C-gamma1 (PLCgamma1) and PLCgamma2 is crucial for B-cell function. While several signaling molecules have been implicated in PLCgamma activation, the mechanism coupling PLCgamma to the BCR remains undefined. The role of PLCgamma1 SH2 and SH3 domains at different steps of BCR-induced PLCgamma1 activation was examined by reconstitution in a PLCgamma-negative B-cell line. PLCgamma1 membrane translocation required a functional SH2 N-terminal [SH2(N)] domain, was decreased by mutation of the SH3 domain, but was unaffected by mutation of the SH2(C) domain. Tyrosine phosphorylation did not require the SH2(C) or SH3 domains but depended exclusively on a functional SH2(N) domain, which mediated the association of PLCgamma1 with the adapter protein, BLNK. Forcing PLCgamma1 to the membrane via a myristoylation signal did not bypass the SH2(N) domain requirement for phosphorylation, indicating that the phosphorylation mediated by this domain is not due to membrane anchoring alone. Mutation of the SH2(N) or the SH2(C) domain abrogated BCR-stimulated phosphoinositide hydrolysis and signaling events, while mutation of the SH3 domain partially decreased signaling. PLCgamma1 SH domains, therefore, have interrelated but distinct roles in BCR-induced PLCgamma1 activation.
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Affiliation(s)
- K E DeBell
- Laboratory of Immunobiology, Division of Monoclonal Antibodies, Center for Biologics Evaluation and Research, Bethesda, Maryland 20892, USA
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22
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Affiliation(s)
- K M Coggeshall
- Department of Microbiology, Ohio State University, Columbus 43210, USA.
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23
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Carroll DJ, Albay DT, Terasaki M, Jaffe LA, Foltz KR. Identification of PLCgamma-dependent and -independent events during fertilization of sea urchin eggs. Dev Biol 1999; 206:232-47. [PMID: 9986735 DOI: 10.1006/dbio.1998.9145] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
At fertilization, sea urchin eggs undergo a series of activation events, including a Ca2+ action potential, Ca2+ release from the endoplasmic reticulum, an increase in intracellular pH, sperm pronuclear formation, MAP kinase dephosphorylation, and DNA synthesis. To examine which of these events might be initiated by activation of phospholipase Cgamma (PLCgamma), which produces the second messengers inositol trisphosphate (IP3) and diacylglycerol, we used recombinant SH2 domains of PLCgamma as specific inhibitors. Sea urchin eggs were co-injected with a GST fusion protein composed of the two tandem SH2 domains of bovine PLCgamma and (1) Ca2+ green dextran to monitor intracellular free Ca2+, (2) BCECF dextran to monitor intracellular pH, (3) Oregon Green dUTP to monitor DNA synthesis, or (4) fluorescein 70-kDa dextran to monitor nuclear envelope formation. Microinjection of the tandem SH2 domains of PLCgamma produced a concentration-dependent inhibition of Ca2+ release and also inhibited cortical granule exocytosis, cytoplasmic alkalinization, MAP kinase dephosphorylation, DNA synthesis, and cleavage after fertilization. However, the Ca2+ action potential, sperm entry, and sperm pronuclear formation were not prevented by injection of the PLCgammaSH2 domain protein. Microinjection of a control protein, the tandem SH2 domains of the phosphatase SHP2, had no effect on Ca2+ release, cortical granule exocytosis, DNA synthesis, or cleavage. Specificity of the inhibitory action of the PLCgammaSH2 domains was further indicated by the finding that microinjection of PLCgammaSH2 domains that had been point mutated at a critical arginine did not inhibit Ca release at fertilization. Additionally, Ca2+ release in response to microinjection of IP3, cholera toxin, cADP ribose, or cGMP was not inhibited by the PLCgammaSH2 fusion protein. These results indicate that PLCgamma plays a key role in several fertilization events in sea urchin eggs, including Ca2+ release and DNA synthesis, but that the action potential, sperm entry, and male pronuclear formation can occur in the absence of PLCgamma activation or Ca2+ increase.
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Affiliation(s)
- D J Carroll
- Department of Molecular, Cellular and Developmental Biology and the Marine Science Institute, University of California at Santa Barbara, 93106-9610, USA
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24
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Wands JR, Lavaissiere L, Moradpour D, de la Monte S, Mohr L, Nicolau C, Tanaka S. Immunological approach to hepatocellular carcinoma. J Viral Hepat 1998; 4 Suppl 2:60-74. [PMID: 9429211 DOI: 10.1111/j.1365-2893.1997.tb00181.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A library of monoclonal antibodies (MoAbs) has been produced against a human hepatocellular carcinoma (HCC) cell line designated FOCUS in order to study the antigenic properties of transformed hepatocytes. Several monoclonal antibodies (MoAbs) were initially selected for study since they bound to antigens which were overexpressed in HCC tissues compared with the adjacent uninvolved normal liver counterpart; in addition, these MoAbs revealed low level antigen expression on other normal human tissues. Subsequently, HCC cell lines were metabolically labelled and the antigens further characterized by immunoprecipitation and Western blot analysis. If the MoAb recognized a primary linear epitope on a protein, cloning was performed using a lambda GT11 cDNA expression library prepared from the FOCUS HCC cell line. These studies characterized the HCC associated antigen(s) at the molecular level. This review illustrates the value of such an experimental approach to search for and identify HCC associated antigens and emphasizes the biological properties of novel proteins may be defined and characterized by these techniques. More important, our investigations have described unique proteins that may not only be important in the pathogenesis of HCC but also demonstrates how such antigen-antibody systems may be used to develop strategies for immunotargetting and gene therapy of HCC.
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Affiliation(s)
- J R Wands
- Molecular Hepatology Laboratory, Massachusetts General Hospital Cancer Center, Charlestown, MA 02129, USA
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25
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Role of Immunoreceptor Tyrosine-Based Activation Motif in Signal Transduction from Antigen and Fc Receptors**Received for publication October 7, 1997. Adv Immunol 1998. [DOI: 10.1016/s0065-2776(08)60608-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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26
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Jackson DE, Kupcho KR, Newman PJ. Characterization of phosphotyrosine binding motifs in the cytoplasmic domain of platelet/endothelial cell adhesion molecule-1 (PECAM-1) that are required for the cellular association and activation of the protein-tyrosine phosphatase, SHP-2. J Biol Chem 1997; 272:24868-75. [PMID: 9312087 DOI: 10.1074/jbc.272.40.24868] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recent studies have shown that the Src homology-2 (SH2) domain-containing protein-tyrosine phosphatase, SHP-2, associates with the cytoplasmic domain of PECAM-1 as it becomes tyrosine-phosphorylated during platelet aggregation: a process that can be mimicked in part by small synthetic phosphopeptides corresponding to the cytoplasmic domain of PECAM-1 encompassing tyrosine residues Tyr-663 or Tyr-686. To further examine the molecular requirements for PECAM-1/SHP-2 interactions, we generated human embryonic kidney (HEK)-293 cell lines that stably expressed mutant forms of PECAM-1 harboring tyrosine to phenylalanine (Tyr --> Phe) mutations in the cytoplasmic domain. Y663F and Y686F forms of PECAM-1 were tyrosine-phosphorylated to a somewhat lesser extent than wild-type PECAM-1, and a doubly substituted Y663,686F form of PECAM-1 failed to become tyrosine-phosphorylated, suggesting that the PECAM-1 cytoplasmic domain tyrosine residues 596, 636 and 701 do not serve as substrates for cellular kinases. Interestingly, SHP-2 binding was lost when either Tyr-663 or Tyr-686 were changed to phenylalanine, indicating that both residues are required for SHP-2/PECAM-1 association. Although PECAM-1 phosphopeptides NSDVQpY663TEVQV and DTETVpY686SEVRK stimulated the catalytic activity of the phosphatase to a similar extent, surface plasmon resonance studies revealed that the Tyr-663-containing peptide had approximately 10-fold higher affinity for SHP-2 than did the Tyr-686 peptide. Finally, peptido-precipitation analysis showed that the NH2-terminal SH2 domain of SHP-2 reacted preferentially with the Tyr-663 PECAM-1 phosphopeptide, while the Tyr-686 phosphopeptide associated only with the COOH-terminal SH2 domain of the phosphatase. Together, these data provide a molecular model for PECAM-1/SHP-2 interactions that may shed light on the downstream events that follow PECAM-1-mediated interactions of vascular cells.
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Affiliation(s)
- D E Jackson
- Blood Research Institute, The Blood Center of Southeastern Wisconsin, Milwaukee, Wisconsin 53233, USA
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27
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Trager JB, Martin GS. The role of the Src homology-2 domain in the lethal effect of Src expression in the yeast Saccharomyces cerevisiae. Int J Biochem Cell Biol 1997; 29:635-48. [PMID: 9363641 DOI: 10.1016/s1357-2725(96)00162-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Expression of the retroviral transforming gene v-src arrests the proliferation of the yeast Saccharomyces cerevisiae. A functional Src SH2 (Src homology 2) domain is required for this arrest. To examine the mechanism by which Src blocks yeast cell proliferation, and to determine the role of the Src SH2 domain in the growth arrest, src variants were expressed in yeast under the control of the galactose-inducible GAL1 promoter. Following galactose induction of Src expression, phosphotyrosyl-proteins were isolated by immunoprecipitation with beads coupled to either anti-phosphotyrosine antibody or to a recombinant fusion protein containing the Src SH2 domain. A group of SH2-binding phosphotyrosyl proteins was detected in cells expressing toxic forms of Src, but were not detected in cells expressing non-toxic variants. This group of phosphotyrosyl-proteins represents a minor subset of the proteins phosphorylated by v-Src. The lethality of v-Src and the phosphorylation of SH2-binding proteins were co-ordinately affected by alterations in phosphotyrosine-phosphatase activity. These observations indicate that the lethality of Src is correlated with the phosphorylation of proteins that bind to the Src SH2 domain. The role of the SH2 domain in determining the lethal effects of Src in yeast may be similar to its role in targeting Src to substrates necessary for its biological effects in vertebrate cells.
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Affiliation(s)
- J B Trager
- Department of Molecular and Cell Biology, University of California at Berkeley 94720-3204, USA
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28
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PDGF and FGF receptors in health and disease. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1874-5687(96)80009-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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29
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Noh DY, Shin SH, Rhee SG. Phosphoinositide-specific phospholipase C and mitogenic signaling. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1242:99-113. [PMID: 7492569 DOI: 10.1016/0304-419x(95)00006-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The importance of PLC activation in cell proliferation is evident from the fact that the hydrolysis of PtdIns(4,5)P2 is one of the early events that follow the interaction of many growth factors and mitogens with their respective receptors. However, the importance of PLC activation is not restricted to proliferation; it is one of the most common transmembrane signaling events elicited by receptors that regulate many other cellular processes, including differentiation, metabolism, secretion, contraction, and sensory perception. It is also clear that cell proliferation signaling does not always require PLC, as indicated by the fact that growth factors such as insulin and CSF-1 do not appear to elicit the hydrolysis of PtdIns(4,5)P2, even though the intracellular domains of their receptors carry a PTK domain and the receptors show topologies very similar to those of the PLC-activating growth factors PDGF, EGF, and FGF. The growth factor-dependent activation of PLC is initiated by the formation of a complex between the receptor PTK and PLC-gamma; the formation of this complex is mediated by a specific interaction between a tyrosine phosphate residue on the intracellular domain of PTK and the SH2 domain of PLC-gamma. The receptor PTK subsequently phosphorylates PLC-gamma, of which two distinct isozymes, PLC-gamma 1 and PLC-gamma 2, have been identified. Proliferation of T cells and B cells in response to the aggregation of their respective cell surface receptors is also accompanied by the activation of PLC-gamma isozymes at an early stage. Unlike growth factor receptors, the T cell and B cell receptors lack intrinsic PTK activity but associate with several non-receptor PTKs of the Src and Syk families. Although the specific kinases are not known, one or more of these enzymes phosphorylate and activate PLC-gamma 1 and PLC-gamma 2. Transduction of growth signals by G protein-coupled receptors such as those for thrombin or bombesin also requires PtdIns(4,5)P2 hydrolysis, which, in this instance, is mediated by PLC-beta isozymes. The PLC-beta subfamily consists of four distinct members: PLC-beta 1, PLC-beta 2, PLC-beta 3, and PLC-beta 4. Agonist interaction with specific G protein-coupled receptors causes the dissociation of Gq proteins into G alpha and G beta gamma subunits and the exchange of GDP bound to G alpha for GTP. The resulting GTP-bound G alpha subunit then activates PLC-beta isoforms by binding to the carboxyl-terminal region of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D Y Noh
- Laboratory of Cell Signaling, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland 20892, USA
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30
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Diakonova M, Payrastre B, van Velzen AG, Hage WJ, van Bergen en Henegouwen PM, Boonstra J, Cremers FF, Humbel BM. Epidermal growth factor induces rapid and transient association of phospholipase C-gamma 1 with EGF-receptor and filamentous actin at membrane ruffles of A431 cells. J Cell Sci 1995; 108 ( Pt 6):2499-509. [PMID: 7673364 DOI: 10.1242/jcs.108.6.2499] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Addition of epidermal growth factor to A431 cells results in dramatic changes in cell morphology. Initially the cells form membrane ruffles accompanied by increased actin polymerization, followed by cell rounding. Activation of the tyrosine kinase of the receptor by binding epidermal growth factor leads also to phosphorylation and activation of phospholipase C-gamma 1, a key enzyme in the phosphoinositide pathway. In this study we have investigated the localization of phospholipase C-gamma 1 during cell activation by epidermal growth factor. It is shown that addition of the growth factor to A431 cells leads to a translocation of phospholipase C-gamma 1 from the cytosol to the membrane fraction. Interestingly, this relocation is exclusively directed to the membrane ruffles. Most of the phospholipase C-gamma 1 associates to the membrane and a small fraction to the underlying skeleton. Immunocytochemical studies demonstrated that phospholipase C-gamma 1 co-localizes with the epidermal growth factor receptor and also filamentous actin at the membrane ruffles. Moreover, using anti-phosphotyrosine antibodies we found that the membrane ruffles are significantly enriched in phosphotyrosyl proteins. Between 5 and 10 minutes after stimulation the membrane ruffles disappear and also the co-localization of phospholipase C-gamma 1 with the epidermal growth factor receptor and filamentous actin. These results support the notion that activation of A431 cells by epidermal growth factor leads to the formation of a signalling complex of its receptor, phospholipase C-gamma 1 and filamentous actin which is primarily localized at membrane ruffles.
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Affiliation(s)
- M Diakonova
- Institute of Cytology, Academy of Science, St Petersburg, Russia
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31
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Polk DB, McCollum GW, Carpenter G. Cell density-dependent regulation of PLC gamma 1 tyrosine phosphorylation and catalytic activity in an intestinal cell line (IEC-6). J Cell Physiol 1995; 162:427-33. [PMID: 7532179 DOI: 10.1002/jcp.1041620315] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Administration of epidermal growth factor (EGF) to rats has been shown to induce both mitogenic and nonmitogenic responses in the intestine. The mechanisms to describe a multiplicity of hormonal responses within a single tissue are unclear but likely involve selectivity among receptor substrates. A nontransformed rat jejunal crypt intestinal epithelial cell line (IEC-6) was studied to determine if the regulation of receptor tyrosine kinase substrates is affected by cell population physiology. EGF stimulated a rapid increase in inositol trisphosphate in confluent but not subconfluent cells. Similarly, treatment of confluent IEC-6 cells with EGF provoked a significant increase in the hydrolysis of PtdIns 4,5-P2 by immunoisolated PLC gamma 1. The tyrosine phosphorylation state of PLC gamma 1 and the association of PLC gamma 1 with the EGF receptor were increased by EGF in confluent cells only. In contrast, the autophosphorylation state of the EGF receptor and the tyrosine phosphorylation state of another SH2-containing EGF receptor substrate SHC were increased by EGF regardless of cell density. Western blot analysis revealed equal protein expression of PLC gamma 1 in confluent and subconfluent cells. EGF receptor protein expression and ligand binding capacity were slightly increased in confluent compared to subconfluent cells. EGF regulation of PLC gamma 1, therefore, is regulated by physiological factors dependent on cell density in IEC-6 cells.
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Affiliation(s)
- D B Polk
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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32
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Abstract
Communication between cells assumes particular importance in multicellular organisms. The growth, migration and differentiation of cells in the embryo, and their organization into specific tissues, depend on signals transmitted from one cell to another. In the adult, cell signalling orchestrates normal cellular behaviour and responses to wounding and infection. The consequences of breakdowns in this signalling underlie cancer, diabetes and disorders of the immune and cardiovascular systems. Conserved protein domains that act as key regulatory participants in many of these different signalling pathways are highlighted.
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Affiliation(s)
- T Pawson
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
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33
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Posner I, Levitzki A. Kinetics of phosphorylation of the SH2-containing domain of phospholipase C gamma 1 by the epidermal growth factor receptor. FEBS Lett 1994; 353:155-61. [PMID: 7926042 DOI: 10.1016/0014-5793(94)00989-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The kinetics of the EGF receptor (EGFR) autophosphorylation and of the phosphorylation by EGFR of a fusion protein (Fp(SH2)) derived from PLC-gamma 1 with two SH2 domains were studied employing purified EGFR or membrane-bound preparations of native and truncated EGFR. With varied ATP concentrations both reactions yielded Michaelis-Menten kinetics. KATP for autophosphorylation was 0.35 microM and for Fp(SH2) phosphorylation 1.35 microM. With Fp(SH2) and were followed by drops to zero velocities at about 1.0 microM Fp(SH2). We conclude that (a) our data support the concept that receptor autophosphorylation is a prerequisite for the interactions between EGFR and the substrate's SH2-domains and their eventual phosphorylation by the receptor, and (b) the interactions between EGFR and the physiological substrate seem to involve mechanisms which allow the substrate to act as an on-off switch in the subsequent substrate phosphorylation reaction.
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Affiliation(s)
- I Posner
- Department of Biological Chemistry, Hebrew University of Jerusalem, Israel
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34
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Payne G, Stolz LA, Pei D, Band H, Shoelson SE, Walsh CT. The phosphopeptide-binding specificity of Src family SH2 domains. CHEMISTRY & BIOLOGY 1994; 1:99-105. [PMID: 9383377 DOI: 10.1016/1074-5521(94)90047-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Src homology 2 (SH2) domains mediate protein/protein interactions by binding phosphotyrosyl proteins with high specificity. The protein Lck, a Src-like lymphocyte-specific tyrosine kinase which is important in signals involved in T-cell development, contains one such domain. The crystal structure of a complex of the Lck SH2 domain with a high-affinity ligand, pY324, is known. This ligand has the sequence EPQpYEEIPIYL. RESULTS We designed and synthesized a series of phosphopeptides with single amino-acid changes in the four residues C-terminal to the phosphotyrosine (pTyr) in pY324. Surprisingly, the Glu one residue C-terminal to the phosphotyrosine (at position pY + 1) is sensitive to substitution, whereas the Ile at position pY + 3 is much less sensitive, accommodating a Glu with only modest loss of binding affinity. Replacement of the Glu and Pro on either side of the Ile had little effect, as predicted. Truncated phosphopeptides that end at position pY + 5 and have only an acetyl group N-terminal to the pTyr bound with only slightly lower affinity than pY324. In addition, naturally occurring phosphopeptide sequences that span a 1,000-fold range in binding affinity for the Lck SH2 domain have been identified. CONCLUSIONS The Lck SH2 domain is highly selective for phosphotyrosyl-peptide binding; its specificity is dictated by the first and third residues C-terminal to the pTyr. The unexpected effects of some amino-acid substitutions indicate that the interactions seen between SH2 domains and ligand in the crystal structure may not be identical to those that occur in solution.
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Affiliation(s)
- G Payne
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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35
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Pinna LA, Donella-Deana A. Phosphorylated synthetic peptides as tools for studying protein phosphatases. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1222:415-31. [PMID: 8038211 DOI: 10.1016/0167-4889(94)90050-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- L A Pinna
- Department of Biological Chemistry, University of Padova, Italy
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36
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Luetteke NC, Phillips HK, Qiu TH, Copeland NG, Earp HS, Jenkins NA, Lee DC. The mouse waved-2 phenotype results from a point mutation in the EGF receptor tyrosine kinase. Genes Dev 1994; 8:399-413. [PMID: 8125255 DOI: 10.1101/gad.8.4.399] [Citation(s) in RCA: 362] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mice harboring the waved-1 (wa-1) and waved-2 (wa-2) mutations exhibit skin and eye abnormalities that are strikingly similar to those of TGF-alpha-deficient mice, and wa-1 and TGF-alpha were recently shown to be allelic. Because the wa-2 mutation was mapped previously to the vicinity of the EGF/TGF-alpha receptor (EGFR) gene on mouse chromosome 11, we hypothesized that the wa-2 phenotype might result from a defect in either the expression or activity of EGFR, or both. In the present report, we show that EGFR mRNA and protein of normal size are expressed in wa-2 liver and skin at levels that are comparable to those in the corresponding normal tissues, and that the ability of wa-2 EGFR to bind ligand is unaltered. However, ligand-dependent autophosphorylation of wa-2 EGFR is diminished 5- to 10-fold in vitro, and the ability of wa-2 EGFR to phosphorylate an exogenous substrate is reduced by > 90% compared with that of the control receptor. EGF-induced tyrosine phosphorylation, including that of EGFR itself, is also diminished in skin, particularly at lower dose of exogenous EGF. To establish the nature of the wa-2 mutation, we determined the nucleotide sequence of the coding region of normal and wa-2 murine EGFR cDNAs. A comparison of these sequences revealed a single-nucleotide transversion resulting in the substitution of a glycine for a conserved valine residue near the amino terminus of the tyrosine kinase domain. The importance of this mutation was confirmed by showing that its introduction into an otherwise normal EGFR markedly reduced the receptor's tyrosine kinase activity in transfected Chinese hamster ovary cells. Finally, in situ hybridization analysis demonstrated expression of EGFR predominantly in the outer root sheath of active hair follicles in neonatal mice. As we previously localized TGF-alpha mRNA to the inner root sheath, this pattern of EGFR expression is consistent with the effect of the wa-2 mutation on hair structure, and together with our previous characterization of TGF-alpha-deficient mice, reveals a critical role for signaling by this ligand/receptor system in skin.
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Affiliation(s)
- N C Luetteke
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill 27599-7295
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37
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Affiliation(s)
- T Pawson
- Division of Molecular and Developmental Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
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38
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Bolander FF. Hormonally Regulated Transcription Factors. Mol Endocrinol 1994. [DOI: 10.1016/b978-0-12-111231-8.50017-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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39
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Fry DW, McMichael A, Singh J, Dobrusin EM, McNamara DJ. Design of a potent peptide inhibitor of the epidermal growth factor receptor tyrosine kinase utilizing sequences based on the natural phosphorylation sites of phospholipase C-gamma 1. Peptides 1994; 15:951-7. [PMID: 7991458 DOI: 10.1016/0196-9781(94)90057-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Peptides that possess primary sequences identical to segments surrounding the natural phosphorylation sites of phospholipase C-gamma 1 (i.e., tyrosines 472, 771, 783, and 1284) have been synthesized and evaluated with respect to substrate kinetics for the epidermal growth factor receptor tyrosine kinase. A peptide that was based on tyrosine 472 was the superior substrate in terms of lowest Km value at 37 microM and had the following amino acid sequence: Lys-His-Lys-Lys-Leu-Ala-Glu-Gly-Ser-Ala-Tyr472-Glu-Glu-Val. This peptide sequence was used as a foundation to make amino acid substitutions and/or chemical modifications directed toward the synthesis of a potent peptide inhibitor. As a result, a nine amino acid peptide was synthesized having a K(i) of 10 microM.
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Affiliation(s)
- D W Fry
- Department of Cancer Research, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, MI 48105
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40
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Stephens LR, Jackson TR, Hawkins PT. Agonist-stimulated synthesis of phosphatidylinositol(3,4,5)-trisphosphate: a new intracellular signalling system? BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1179:27-75. [PMID: 8399352 DOI: 10.1016/0167-4889(93)90072-w] [Citation(s) in RCA: 383] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- L R Stephens
- Department of Development and Signalling, AFRC Babraham Institute, Cambridge, UK
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41
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Activation of the SH2-containing phosphotyrosine phosphatase SH-PTP2 by its binding site, phosphotyrosine 1009, on the human platelet-derived growth factor receptor. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80562-6] [Citation(s) in RCA: 231] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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42
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Sierke SL, Koland JG. SH2 domain proteins as high-affinity receptor tyrosine kinase substrates. Biochemistry 1993; 32:10102-8. [PMID: 7691170 DOI: 10.1021/bi00089a028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Activation of a growth factor receptor tyrosine kinase (RTK) is accompanied by a rapid autophosphorylation of the receptor on tyrosine residues. Receptor activation has been shown to promote the association of signal-transducing proteins containing SH2 domains (second domain of src homology). These receptor-associated proteins can, in turn, be phosphorylated by the RTK, an event which presumably regulates their activities. It has been suggested that SH2 domains in signal-transducing proteins target these proteins as substrates of the activated RTK. To test this hypothesis, recombinant proteins were generated that contained tyrosine phosphorylation sites of the erbB3 receptor and/or the SH2 domain of c-src. Incorporation of the SH2 domain led to a decrease in KM and an increase in Vmax for the substrate. The KM determined for one chimeric SH2/erbB3 substrate was among the lowest reported for epidermal growth factor RTK substrates. Experiments with a truncated kinase lacking C-terminal autophosphorylation sites indicated that the reduction in KM for these substrates was mediated by interactions between the substrate SH2 domain and phosphotyrosine residues of the RTK. These interactions could also inhibit RTK activity. These results demonstrate that the SH2 domain can effectively target substrates to a RTK and that SH2 domain proteins can regulate RTK activity.
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Affiliation(s)
- S L Sierke
- Department of Pharmacology, The University of Iowa, Iowa City 52242-1109
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43
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McNamara DJ, Dobrusin EM, Zhu G, Decker SJ, Saltiel AR. Inhibition of binding of phospholipase C gamma 1 SH2 domains to phosphorylated epidermal growth factor receptor by phosphorylated peptides. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1993; 42:240-8. [PMID: 8225779 DOI: 10.1111/j.1399-3011.1993.tb00138.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A series of tyrosine-containing peptides 1-12: [formula: see text] (six pairs with and without the tyrosine phosphorylated) has been synthesized. The peptides were derived from tyrosine autophosphorylation sites in the epidermal growth factor receptor (EGFR): Tyr 992, 1068, 1148 and 1173. Peptide 1, derived from the Tyr 992 site, inhibited binding of a 35S-labelled fusion protein containing both of the SH2 domains from PLC gamma 1 to the phosphorylated EGFR with an IC50 of 8 microM. All of the phosphorylated peptides except 11 (1, 3, 5, 7 and 9) inhibited this binding to some degree (20-55%) at 10 microM. The nonphosphorylated peptides were inactive in this assay. The nonphosphorylated peptides 2, 4, 6, 8, 10 and 12 were obtained by standard solid-phase synthetic methodologies using both Boc/benzyl and Fmoc/tert-butyl strategies. The phosphorylated peptides 1, 3, 5, 7, 9 and 11 were similarly obtained using a Fmoc/tert-butyl strategy incorporating unprotected N alpha-Fmoc-Tyr, followed by phosphitylation and oxidation of the tyrosine in the resin-bound peptide. In addition, Asp-Ala-Asp-Glu-Phe992(4-CH2PO3H2)-Leu-Ile-Pro-Gln-Gln-Gly-O H (15), an analog of 1 incorporating an enzymatically stable phosphotyrosine mimic, 4-phosphonomethyl-L-phenylalanine, was synthesized and found to be inactive.
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Affiliation(s)
- D J McNamara
- Department of Medicinal Chemistry, Warner-Lambert Company, Ann Arbor, Michigan
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44
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Widmer HR, Ohsawa F, Knüsel B, Hefti F. Down-regulation of phosphatidylinositol response to BDNF and NT-3 in cultures of cortical neurons. Brain Res 1993; 614:325-34. [PMID: 8348325 DOI: 10.1016/0006-8993(93)91051-s] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The hydrolysis of phosphatidyl 4,5-bisphosphate (PI), which is involved in the transduction mechanism of neurotransmitters and growth factors, is stimulated by brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in primary cultures of fetal brain neurons. In the present study we sought to examine the effect of pretreatment with these factors on their acute stimulation capabilities and, furthermore, to substantiate that the effects of BDNF and NT-3 reflect actions on neurons rather than glial cells. Pretreatment with BNDF and NT-3 for 4 days followed by 1 day without growth factor abolished the effect of an acute stimulation with these factors. The growth factors were mutually effective so that BDNF pretreatment abolished the acute response to NT-3 and vice versa. In contrast, the effects of bFGF (basic fibroblast growth factor, a non-neurotrophin growth factor) also stimulating PI hydrolysis in these culture systems, were not reduced by neurotrophin pretreatment. Pretreatment with K-252b, at concentrations known to inhibit trk receptors, did not alter the acute stimulation of PI hydrolysis induced by the neutrophins. PI hydrolysis stimulated by BDNF and NT-3 in cultures grown in presence of cytosine arabinoside C, containing > 95% neurons, was higher than in cultures containing non-neuronal cells, indicating that the neurotrophin stimulation occurs in neuronal cells. No stimulatory effect was detected in bFGF treated pure neuronal cultures. The findings suggest that prolonged exposure of responsive neurons to BDNF and NT-3 down-regulates their stimulatory effects on PI hydrolysis.
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Affiliation(s)
- H R Widmer
- Division of Neurogerontology, Andrus Gerontology Center, University of Southern California, Los Angeles 90089
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45
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Yang L, Camoratto A, Baffy G, Raj S, Manning D, Williamson J. Epidermal growth factor-mediated signaling of G(i)-protein to activation of phospholipases in rat-cultured hepatocytes. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53756-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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46
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Tsygankov A, Bröker B, Fargnoli J, Ledbetter J, Bolen J. Activation of tyrosine kinase p60fyn following T cell antigen receptor cross-linking. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36951-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Affiliation(s)
- J Schlessinger
- New York University Medical Center, Department of Pharmacology, New York 10016
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48
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Lowenstein EJ, Daly RJ, Batzer AG, Li W, Margolis B, Lammers R, Ullrich A, Skolnik EY, Bar-Sagi D, Schlessinger J. The SH2 and SH3 domain-containing protein GRB2 links receptor tyrosine kinases to ras signaling. Cell 1992; 70:431-42. [PMID: 1322798 DOI: 10.1016/0092-8674(92)90167-b] [Citation(s) in RCA: 1242] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A cDNA clone encoding a novel, widely expressed protein (called growth factor receptor-bound protein 2 or GRB2) containing one src homology 2 (SH2) domain and two SH3 domains was isolated. Immunoblotting experiments indicate that GRB2 associates with tyrosine-phosphorylated epidermal growth factor receptors (EGFRs) and platelet-derived growth factor receptors (PDGFRs) via its SH2 domain. Interestingly, GRB2 exhibits striking structural and functional homology to the C. elegans protein sem-5. It has been shown that sem-5 and two other genes called let-23 (EGFR like) and let-60 (ras like) lie along the same signal transduction pathway controlling C. elegans vulval induction. To examine whether GRB2 is also a component of ras signaling in mammalian cells, microinjection studies were performed. While injection of GRB2 or H-ras proteins alone into quiescent rat fibroblasts did not have mitogenic effect, microinjection of GRB2 together with H-ras protein stimulated DNA synthesis. These results suggest that GRB2/sem-5 plays a crucial role in a highly conserved mechanism for growth factor control of ras signaling.
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Affiliation(s)
- E J Lowenstein
- Department of Pharmacology, New York University Medical Center, New York 10016
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49
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