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Sandouk A, Xu Z, Baruah S, Tremblay M, Hopkins JB, Chakravarthy S, Gakhar L, Schnicker NJ, Houtman JCD. GRB2 dimerization mediated by SH2 domain-swapping is critical for T cell signaling and cytokine production. Sci Rep 2023; 13:3505. [PMID: 36864087 PMCID: PMC9981690 DOI: 10.1038/s41598-023-30562-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 02/25/2023] [Indexed: 03/04/2023] Open
Abstract
GRB2 is an adaptor protein required for facilitating cytoplasmic signaling complexes from a wide array of binding partners. GRB2 has been reported to exist in either a monomeric or dimeric state in crystal and solution. GRB2 dimers are formed by the exchange of protein segments between domains, otherwise known as "domain-swapping". Swapping has been described between SH2 and C-terminal SH3 domains in the full-length structure of GRB2 (SH2/C-SH3 domain-swapped dimer), as well as between α-helixes in isolated GRB2 SH2 domains (SH2/SH2 domain-swapped dimer). Interestingly, SH2/SH2 domain-swapping has not been observed within the full-length protein, nor have the functional influences of this novel oligomeric conformation been explored. We herein generated a model of full-length GRB2 dimer with an SH2/SH2 domain-swapped conformation supported by in-line SEC-MALS-SAXS analyses. This conformation is consistent with the previously reported truncated GRB2 SH2/SH2 domain-swapped dimer but different from the previously reported, full-length SH2/C-terminal SH3 (C-SH3) domain-swapped dimer. Our model is also validated by several novel full-length GRB2 mutants that favor either a monomeric or a dimeric state through mutations within the SH2 domain that abrogate or promote SH2/SH2 domain-swapping. GRB2 knockdown and re-expression of selected monomeric and dimeric mutants in a T cell lymphoma cell line led to notable defects in clustering of the adaptor protein LAT and IL-2 release in response to TCR stimulation. These results mirrored similarly-impaired IL-2 release in GRB2-deficient cells. These studies show that a novel dimeric GRB2 conformation with domain-swapping between SH2 domains and monomer/dimer transitions are critical for GRB2 to facilitate early signaling complexes in human T cells.
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Affiliation(s)
- Aline Sandouk
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, 52242, USA
| | - Zhen Xu
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Sankar Baruah
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Mikaela Tremblay
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, 52242, USA
| | - Jesse B Hopkins
- Biophysics Collaborative Access Team, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Srinivas Chakravarthy
- Biophysics Collaborative Access Team, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Lokesh Gakhar
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biochemistry and Molecular Biology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Nicholas J Schnicker
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Jon C D Houtman
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, 52242, USA.
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, 52242, USA.
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Gregor T, Bosakova MK, Nita A, Abraham SP, Fafilek B, Cernohorsky NH, Rynes J, Foldynova-Trantirkova S, Zackova D, Mayer J, Trantirek L, Krejci P. Elucidation of protein interactions necessary for the maintenance of the BCR-ABL signaling complex. Cell Mol Life Sci 2020; 77:3885-3903. [PMID: 31820037 PMCID: PMC11104816 DOI: 10.1007/s00018-019-03397-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 11/05/2019] [Accepted: 11/26/2019] [Indexed: 10/25/2022]
Abstract
Many patients with chronic myeloid leukemia in deep remission experience return of clinical disease after withdrawal of tyrosine kinase inhibitors (TKIs). This suggests signaling of inactive BCR-ABL, which allows the survival of cancer cells, and relapse. We show that TKI treatment inhibits catalytic activity of BCR-ABL, but does not dissolve BCR-ABL core signaling complex, consisting of CRKL, SHC1, GRB2, SOS1, cCBL, p85a-PI3K, STS1 and SHIP2. Peptide microarray and co-immunoprecipitation results demonstrate that CRKL binds to proline-rich regions located in C-terminal, intrinsically disordered region of BCR-ABL, that SHC1 requires pleckstrin homology, src homology and tyrosine kinase domains of BCR-ABL for binding, and that BCR-ABL sequence motif located in disordered region around phosphorylated tyrosine 177 mediates binding of three core complex members, i.e., GRB2, SOS1, and cCBL. Further, SHIP2 binds to the src homology and tyrosine kinase domains of BCR-ABL and its inositol phosphatase activity contributes to BCR-ABL-mediated phosphorylation of SHC1. Together, this study characterizes protein-protein interactions within the BCR-ABL core complex and determines the contribution of particular BCR-ABL domains to downstream signaling. Understanding the structure and dynamics of BCR-ABL interactome is critical for the development of drugs targeting integrity of the BCR-ABL core complex.
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MESH Headings
- Adaptor Proteins, Signal Transducing/metabolism
- Amino Acid Motifs
- Binding Sites
- Cell Line, Tumor
- Fusion Proteins, bcr-abl/chemistry
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- HEK293 Cells
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases/metabolism
- Phosphorylation
- Protein Array Analysis
- Protein Binding/drug effects
- Protein Kinase Inhibitors/pharmacology
- Pyrimidines/pharmacology
- Signal Transduction/drug effects
- Src Homology 2 Domain-Containing, Transforming Protein 1/metabolism
- src Homology Domains
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Affiliation(s)
- Tomas Gregor
- Central European Institute of Technology, Masaryk University, 62500, Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
- International Clinical Research Center, St. Anne's University Hospital, 65691, Brno, Czech Republic
| | - Michaela Kunova Bosakova
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
- International Clinical Research Center, St. Anne's University Hospital, 65691, Brno, Czech Republic
- Institute of Animal Physiology and Genetics of the CAS, 60200, Brno, Czech Republic
| | - Alexandru Nita
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
- Institute of Organic Chemistry and Biochemistry of the CAS, 16610, Prague, Czech Republic
| | - Sara P Abraham
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Bohumil Fafilek
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
- International Clinical Research Center, St. Anne's University Hospital, 65691, Brno, Czech Republic
- Institute of Animal Physiology and Genetics of the CAS, 60200, Brno, Czech Republic
| | - Nicole H Cernohorsky
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Jan Rynes
- Central European Institute of Technology, Masaryk University, 62500, Brno, Czech Republic
| | | | - Daniela Zackova
- Department of Internal Medicine, Hematology and Oncology, Masaryk University Hospital, 62500, Brno, Czech Republic
| | - Jiri Mayer
- Department of Internal Medicine, Hematology and Oncology, Masaryk University Hospital, 62500, Brno, Czech Republic
| | - Lukas Trantirek
- Central European Institute of Technology, Masaryk University, 62500, Brno, Czech Republic.
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic.
- International Clinical Research Center, St. Anne's University Hospital, 65691, Brno, Czech Republic.
- Institute of Animal Physiology and Genetics of the CAS, 60200, Brno, Czech Republic.
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Jang HD, Hwang HZ, Kim HS, Lee SY. C-Cbl negatively regulates TRAF6-mediated NF- κB activation by promoting K48-linked polyubiquitination of TRAF6. Cell Mol Biol Lett 2019; 24:29. [PMID: 31123462 PMCID: PMC6518801 DOI: 10.1186/s11658-019-0156-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 05/06/2019] [Indexed: 01/06/2023] Open
Abstract
Background In its RING domain, tumor necrosis factor receptor-associated factor 6 (TRAF6) has ubiquitin E3 ligase activity that facilitates the formation of lysine 63-linked polyubiquitin chains. This activity is required to activate nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and plays an important role in the IκB kinase (IKK) complex. Methods An in vitro ubiquitination assay was used to establish whether c-Cbl could promote TRAF6 ubiquitination. We assessed direct binding and performed fine mapping between c-Cbl and TRAF6 based on the results of an immunoprecipitation assay with cultured 293 T cells. The luciferase reporter assay was applied to establish if c-Cbl-mediated ubiquitination affected NF-κB activation after stimulus from various TRAF-mediated signals: tumor necrosis factor-α (TNF-α), receptor activator of NF-κB ligand (RANKL), and interleukin-1β (IL-1β). An in vivo ubiquitination assay was performed using endogenous immunoprecipitation of TRAF6 in bone marrow macrophages (BMMs) and osteoclasts. Results Here, we report on a form of TRAF6 ubiquitination that is mediated by c-Cbl, leading to the formation of lysine 48-linked polyubiquitin chains. The NF-κB activity induced by RANKL and IL-1β treatment is inhibited when c-Cbl is overexpressed, while the NF-κB activity induced by TNFα treatment is not. c-Cbl inhibits NF-κB activity mediated by TRAF6, but not by TRAF2. These findings show that c-Cbl ubiquitin ligase activity is essential for TRAF6 ubiquitination and negative regulation of NF-κB activity. Fine mapping revealed that the proline-rich domain of c-Cbl is critical for interaction with TRAF6. Stimulation with RANKL or interferon-γ (IFN-γ) caused c-Cbl to bind to polyubiquitinated TRAF6. Conclusions These findings indicate that the interaction of TRAF6 with c-Cbl causes lysine 48-linked polyubiquitination for both negative feedback regulation and signaling cross-talk between RANKL and IFN-γ.
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Affiliation(s)
- Hyun-Duk Jang
- 1National Leading Laboratory for Stem Cell Research, Seoul National University College of Medicine, Seoul, South Korea.,2Korea Research-Driven Hospital, Biomedical Research Institute, Seoul National University Hospital, Seoul, South Korea.,3Strategic Center of Cell & Bio Therapy, Seoul National University Hospital, Seoul, South Korea
| | - Hye Zin Hwang
- 4Department of Biotechnology, The Catholic University of Korea, Bucheon, South Korea
| | - Hyo-Soo Kim
- 1National Leading Laboratory for Stem Cell Research, Seoul National University College of Medicine, Seoul, South Korea.,2Korea Research-Driven Hospital, Biomedical Research Institute, Seoul National University Hospital, Seoul, South Korea.,3Strategic Center of Cell & Bio Therapy, Seoul National University Hospital, Seoul, South Korea.,5Cardiovascular Center & Department of Internal Medicine, Seoul National University Hospital, Seoul, South Korea
| | - Soo Young Lee
- 6Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Woman's University, Seoul, South Korea
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Nadeau SA, An W, Mohapatra BC, Mushtaq I, Bielecki TA, Luan H, Zutshi N, Ahmad G, Storck MD, Sanada M, Ogawa S, Band V, Band H. Structural Determinants of the Gain-of-Function Phenotype of Human Leukemia-associated Mutant CBL Oncogene. J Biol Chem 2017; 292:3666-3682. [PMID: 28082680 DOI: 10.1074/jbc.m116.772723] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Indexed: 01/19/2023] Open
Abstract
Mutations of the tyrosine kinase-directed ubiquitin ligase CBL cause myeloid leukemias, but the molecular determinants of the dominant leukemogenic activity of mutant CBL oncogenes are unclear. Here, we first define a gain-of-function attribute of the most common leukemia-associated CBL mutant, Y371H, by demonstrating its ability to increase proliferation of hematopoietic stem/progenitor cells (HSPCs) derived from CBL-null and CBL/CBL-B-null mice. Next, we express second-site point/deletion mutants of CBL-Y371H in CBL/CBL-B-null HSPCs or the cytokine-dependent human leukemic cell line TF-1 to show that individual or combined Tyr → Phe mutations of established phosphotyrosine residues (Tyr-700, Tyr-731, and Tyr-774) had little impact on the activity of the CBL-Y371H mutant in HSPCs, and the triple Tyr → Phe mutant was only modestly impaired in TF-1 cells. In contrast, intact tyrosine kinase-binding (TKB) domain and proline-rich region (PRR) were critical in both cell models. PRR deletion reduced the stem cell factor (SCF)-induced hyper-phosphorylation of the CBL-Y371H mutant and the c-KIT receptor and eliminated the sustained p-ERK1/2 and p-AKT induction by SCF. GST fusion protein pulldowns followed by phospho-specific antibody array analysis identified distinct CBL TKB domains or PRR-binding proteins that are phosphorylated in CBL-Y371H-expressing TF-1 cells. Our results support a model of mutant CBL gain-of-function in which mutant CBL proteins effectively compete with the remaining wild type CBL-B and juxtapose TKB domain-associated PTKs with PRR-associated signaling proteins to hyper-activate signaling downstream of hematopoietic growth factor receptors. Elucidation of mutant CBL domains required for leukemogenesis should facilitate targeted therapy approaches for patients with mutant CBL-driven leukemias.
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Affiliation(s)
- Scott A Nadeau
- From the Eppley Institute for Research in Cancer and Allied Diseases.,the Departments of Genetics, Cell Biology and Anatomy
| | - Wei An
- From the Eppley Institute for Research in Cancer and Allied Diseases.,the Departments of Genetics, Cell Biology and Anatomy
| | - Bhopal C Mohapatra
- From the Eppley Institute for Research in Cancer and Allied Diseases.,Biochemistry and Molecular Biology
| | - Insha Mushtaq
- From the Eppley Institute for Research in Cancer and Allied Diseases.,Pathology and Microbiology, College of Medicine, and
| | | | - Haitao Luan
- From the Eppley Institute for Research in Cancer and Allied Diseases.,the Departments of Genetics, Cell Biology and Anatomy
| | - Neha Zutshi
- From the Eppley Institute for Research in Cancer and Allied Diseases.,Pathology and Microbiology, College of Medicine, and
| | - Gulzar Ahmad
- From the Eppley Institute for Research in Cancer and Allied Diseases
| | - Matthew D Storck
- From the Eppley Institute for Research in Cancer and Allied Diseases
| | - Masashi Sanada
- the Department of Pathology and Tumor Biology, Kyoto University, Yoshida-Konoe-Cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Seishi Ogawa
- the Department of Pathology and Tumor Biology, Kyoto University, Yoshida-Konoe-Cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Vimla Band
- From the Eppley Institute for Research in Cancer and Allied Diseases.,the Departments of Genetics, Cell Biology and Anatomy.,the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198 and
| | - Hamid Band
- From the Eppley Institute for Research in Cancer and Allied Diseases, .,the Departments of Genetics, Cell Biology and Anatomy.,Biochemistry and Molecular Biology.,Pathology and Microbiology, College of Medicine, and.,the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198 and
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5
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Danzer C, Koller A, Baier J, Arnold H, Giessler C, Opoka R, Schmidt S, Willers M, Mihai S, Parsch H, Wirtz S, Daniel C, Reinhold A, Engelmann S, Kliche S, Bogdan C, Hoebe K, Mattner J. A mutation within the SH2 domain of slp-76 regulates the tissue distribution and cytokine production of iNKT cells in mice. Eur J Immunol 2016; 46:2121-36. [PMID: 27349342 DOI: 10.1002/eji.201646331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 05/18/2016] [Accepted: 06/23/2016] [Indexed: 01/01/2023]
Abstract
TCR ligation is critical for the selection, activation, and integrin expression of T lymphocytes. Here, we explored the role of the TCR adaptor protein slp-76 on iNKT-cell biology. Compared to B6 controls, slp-76(ace/ace) mice carrying a missense mutation (Thr428Ile) within the SH2-domain of slp-76 showed an increase in iNKT cells in the thymus and lymph nodes, but a decrease in iNKT cells in spleens and livers, along with reduced ADAP expression and cytokine response. A comparable reduction in iNKT cells was observed in the livers and spleens of ADAP-deficient mice. Like ADAP(-/-) iNKT cells, slp-76(ace/ace) iNKT cells were characterized by enhanced CD11b expression, correlating with an impaired induction of the TCR immediate-early gene Nur77 and a decreased adhesion to ICAM-1. Furthermore, CD11b-intrinsic effects inhibited cytokine release, concanavalin A-mediated inflammation, and iNKT-cell accumulation in the liver. Unlike B6 and ADAP(-/-) mice, the expression of the transcription factors Id3 and PLZF was reduced, whereas NP-1-expression was enhanced in slp-76(ace/ace) mice. Blockade of NP-1 decreased the recovery of iNKT cells from peripheral lymph nodes, identifying NP-1 as an iNKT-cell-specific adhesion factor. Thus, slp-76 contributes to the regulation of the tissue distribution, PLZF, and cytokine expression of iNKT cells via ADAP-dependent and -independent mechanisms.
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Affiliation(s)
- Claudia Danzer
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Anna Koller
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Julia Baier
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Harald Arnold
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Claudia Giessler
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Robert Opoka
- Division of Immunobiology, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Stephanie Schmidt
- Division of Immunobiology, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Maike Willers
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Sidonia Mihai
- Zentrallabor, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Hans Parsch
- Zentrallabor, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Stefan Wirtz
- Medizinische Klinik 1, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Daniel
- Nephropathologische Abteilung, Universitätsklinikum Erlangen and Friedrich-Alexander University (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Annegret Reinhold
- Institute of Molecular and Clinical Immunology, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Swen Engelmann
- Institute of Molecular and Clinical Immunology, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Stefanie Kliche
- Institute of Molecular and Clinical Immunology, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Christian Bogdan
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Kasper Hoebe
- Division of Immunobiology, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Jochen Mattner
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany. .,Division of Immunobiology, Cincinnati Children's Hospital, Cincinnati, OH, USA.
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Chapter Six - The Ubiquitin Network in the Control of EGFR Endocytosis and Signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:225-76. [DOI: 10.1016/bs.pmbts.2016.03.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Ashizawa AT, Cortes J. Liposomal delivery of nucleic acid-based anticancer therapeutics: BP-100-1.01. Expert Opin Drug Deliv 2014; 12:1107-20. [PMID: 25539721 DOI: 10.1517/17425247.2015.996545] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Antisense oligonucleotides, siRNA, anti-microRNA are designed to selectively bind to target mRNAs, and silence disease-causing or -associated proteins. The clinical development of nucleic acid drugs has been limited by their poor bioavailability. AREAS COVERED This review article examines the strategies that have been utilized to improve the bioavailability of nucleic acids. The chemical modifications made to nucleic acids that have improved their resistance against nuclease degradation are briefly discussed. The design of cationic and neutral lipid nanoparticles that enable the systemic delivery of nucleic acids in vivo is reviewed, and the proof-of-concept evidence that intravenous administration of nucleic acids incorporated into lipid nanoparticles leads to decreased expression of target genes in humans. Preclinical results of the neutral BP-100-1.01 nanoparticle are highlighted. EXPERT OPINION To further improve the clinical potential of nucleic acid cancer drugs, we predict research on the next generation of lipid nanoparticles will focus on: i) enhancing nucleic acid delivery to poorly vascularized tumors, as well as tumors behind the blood-brain barrier; and ii) improving the accessibility of nucleic acids to the cytoplasm by enhancing endosomal escape of nucleic acids and/or reducing exocytosis of nucleic acids to the external milieu.
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Affiliation(s)
- Ana Tari Ashizawa
- BioPath Holdings, Inc. , 4710 Bellaire Blvd Suite 210, Houston, TX 77401 , USA +1 713 385 4392 ;
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Mohapatra B, Ahmad G, Nadeau S, Zutshi N, An W, Scheffe S, Dong L, Feng D, Goetz B, Arya P, Bailey TA, Palermo N, Borgstahl GEO, Natarajan A, Raja SM, Naramura M, Band V, Band H. Protein tyrosine kinase regulation by ubiquitination: critical roles of Cbl-family ubiquitin ligases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:122-39. [PMID: 23085373 DOI: 10.1016/j.bbamcr.2012.10.010] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/05/2012] [Accepted: 10/08/2012] [Indexed: 12/20/2022]
Abstract
Protein tyrosine kinases (PTKs) coordinate a broad spectrum of cellular responses to extracellular stimuli and cell-cell interactions during development, tissue homeostasis, and responses to environmental challenges. Thus, an understanding of the regulatory mechanisms that ensure physiological PTK function and potential aberrations of these regulatory processes during diseases such as cancer are of broad interest in biology and medicine. Aside from the expected role of phospho-tyrosine phosphatases, recent studies have revealed a critical role of covalent modification of activated PTKs with ubiquitin as a critical mechanism of their negative regulation. Members of the Cbl protein family (Cbl, Cbl-b and Cbl-c in mammals) have emerged as dominant "activated PTK-selective" ubiquitin ligases. Structural, biochemical and cell biological studies have established that Cbl protein-dependent ubiquitination targets activated PTKs for degradation either by facilitating their endocytic sorting into lysosomes or by promoting their proteasomal degradation. This mechanism also targets PTK signaling intermediates that become associated with Cbl proteins in a PTK activation-dependent manner. Cellular and animal studies have established that the relatively broadly expressed mammalian Cbl family members Cbl and Cbl-b play key physiological roles, including their critical functions to prevent the transition of normal immune responses into autoimmune disease and as tumor suppressors; the latter function has received validation from human studies linking mutations in Cbl to human leukemia. These newer insights together with embryonic lethality seen in mice with a combined deletion of Cbl and Cbl-b genes suggest an unappreciated role of the Cbl family proteins, and by implication the ubiquitin-dependent control of activated PTKs, in stem/progenitor cell maintenance. Future studies of existing and emerging animal models and their various cell lineages should help test the broader implications of the evolutionarily-conserved Cbl family protein-mediated, ubiquitin-dependent, negative regulation of activated PTKs in physiology and disease.
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Affiliation(s)
- Bhopal Mohapatra
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
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Makishima H, Sugimoto Y, Szpurka H, Clemente MJ, Ng KP, Muramatsu H, O'Keefe C, Saunthararajah Y, Maciejewski JP. CBL mutation-related patterns of phosphorylation and sensitivity to tyrosine kinase inhibitors. Leukemia 2012; 26:1547-54. [PMID: 22246246 DOI: 10.1038/leu.2012.7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Recurrent homozygous CBL-inactivating mutations in myeloid malignancies decrease ubiquitin ligase activity that inactivates SRC family kinases (SFK) and receptor tyrosine kinases (RTK). However, the most important SFK and RTK affected by these mutations, and hence, the most important therapeutic targets, have not been clearly characterized. We compared SFK and RTK pathway activity and inhibitors in acute myeloid leukemia cell lines containing homozygous R420Q mutation (GDM-1), heterozygous deletion (MOLM13) and wild-type (WT) CBL (THP1, U937). As expected with CBL loss, GDM-1 displayed high KIT expression and granulocyte-macrophage colony-stimulating factor (GM-CSF) hypersensitivity. Ectopic expression of WT CBL decreased GDM-1 proliferation but not cell lines with WT CBL. GDM-1, but not the other cell lines, was highly sensitive to growth inhibition by dasatinib (dual SFK and RTK inhibitor, LD50 50 nM); there was less or no selective inhibition of GDM-1 growth by sunitinib (RTK inhibitor), imatinib (ABL, KIT inhibitor), or PP2 (SFK inhibitor). Phosphoprotein analysis identified phosphorylation targets uniquely inhibited by dasatinib treatment of GDM-1, including a number of proteins in the KIT and GM-CSF receptor pathways (for example, KIT Tyr721, STAT3 Tyr705). In conclusion, the promiscuous effects of CBL loss on SFK and RTK signaling appear to be best targeted by dual SFK and RTK inhibition.
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Affiliation(s)
- H Makishima
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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Pedraza-Alva G, Mérida LB, del Rio R, Fierro NA, Cruz-Muñoz ME, Olivares N, Melchy E, Igras V, Holländer GA, Burakoff SJ, Rosenstein Y. CD43 regulates the threshold for T cell activation by targeting Cbl functions. IUBMB Life 2011; 63:940-8. [PMID: 21905200 DOI: 10.1002/iub.554] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/12/2011] [Indexed: 01/27/2023]
Abstract
T cell (TC) activation requires the coordinated signaling of the T cell receptor (TCR) and coreceptor molecules, allowing TCs to respond to lower degrees of TCR occupancy. Coreceptor molecules set the threshold for TC activation by controlling different regulatory signaling loops. The Cbl family members prevent undesired activation of T cells by regulating TCR signals. In this report, we show that TC prestimulation by the CD43 coreceptor molecule before TCR engagement inhibits TCR-dependent c-Cbl tyrosine phosphorylation, c-Cbl interaction with the adapter molecule Crk-L and promotes Cbl-b degradation in a PKCθ-dependent manner. Consequently, the prolonged tyrosine phosphorylation and delayed degradation of ZAP-70 and of the ζ chain lead to enhanced mitogen-activated protein kinase activation and robust TC response. These data indicates that CD43-mediated signals lower the threshold for TC activation by restricting the c-Cbl and Cbl-b inhibitory effects on TCR signaling. In addition to the strength and duration of intracellular signals, our data underscore temporality with which certain molecules are engaged as yet another mechanism to fine tune TC signal quality, and ultimately immune function.
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Affiliation(s)
- Gustavo Pedraza-Alva
- Instituto de Biotecnología, Departamento de Medicina Molecular y Bioprocesos, Universidad Nacional Autónoma de México, Cuernavaca, Mor. México 62210
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12
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Abstract
The growth factor receptor-bound protein 2 (Grb2) is a ubiquitously expressed and evolutionary conserved adapter protein possessing a plethora of described interaction partners for the regulation of signal transduction. In B lymphocytes, the Grb2-mediated scaffolding function controls the assembly and subcellular targeting of activating as well as inhibitory signalosomes in response to ligation of the antigen receptor. Also, integration of simultaneous signals from B-cell coreceptors that amplify or attenuate antigen receptor signal output relies on Grb2. Hence, Grb2 is an essential signal integrator. The key question remains, however, of how pathway specificity can be maintained during signal homeostasis critically required for the balance between immune cell activation and tolerance induction. Here, we summarize the molecular network of Grb2 in B cells and introduce a proteomic approach to elucidate the interactome of Grb2 in vivo.
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Affiliation(s)
- Konstantin Neumann
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
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13
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Ryan PE, Sivadasan-Nair N, Nau MM, Nicholas S, Lipkowitz S. The N terminus of Cbl-c regulates ubiquitin ligase activity by modulating affinity for the ubiquitin-conjugating enzyme. J Biol Chem 2010; 285:23687-98. [PMID: 20525694 DOI: 10.1074/jbc.m109.091157] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cbl proteins are ubiquitin ligases (E3s) that play a significant role in regulating tyrosine kinase signaling. There are three mammalian family members: Cbl, Cbl-b, and Cbl-c. All have a highly conserved N-terminal tyrosine kinase binding domain, a catalytic RING finger domain, and a C-terminal proline-rich domain that mediates interactions with Src homology 3 (SH3) containing proteins. Although both Cbl and Cbl-b have been studied widely, little is known about Cbl-c. Published reports have demonstrated that the N terminus of Cbl and Cbl-b have an inhibitory effect on their respective E3 activity. However, the mechanism for this inhibition is still unknown. In this study we demonstrate that the N terminus of Cbl-c, like that of Cbl and Cbl-b, inhibits the E3 activity of Cbl-c. Furthermore, we map the region responsible for the inhibition to the EF-hand and SH2 domains. Phosphorylation of a critical tyrosine (Tyr-341) in the linker region of Cbl-c by Src or a phosphomimetic mutation of this tyrosine (Y341E) is sufficient to increase the E3 activity of Cbl-c. We also demonstrate for the first time that phosphorylation of Tyr-341 or the Y341E mutation leads to a decrease in affinity for the ubiquitin-conjugating enzyme (E2), UbcH5b. The decreased affinity of the Y341E mutant Cbl-c for UbcH5b results in a more rapid turnover of bound UbcH5b coincident with the increased E3 activity. These data suggest that the N terminus of Cbl-c contributes to the binding to the E2 and that phosphorylation of Tyr-341 leads to a decrease in affinity and an increase in the E3 activity of Cbl-c.
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Affiliation(s)
- Philip E Ryan
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA
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14
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Daniel JL, Dangelmaier CA, Mada S, Buitrago L, Jin J, Langdon WY, Tsygankov AY, Kunapuli SP, Sanjay A. Cbl-b is a novel physiologic regulator of glycoprotein VI-dependent platelet activation. J Biol Chem 2010; 285:17282-91. [PMID: 20400514 DOI: 10.1074/jbc.m109.080200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cbl-b, a member of the Cbl family of E3 ubiquitin ligases, plays an important role in the activation of lymphocytes. However, its function in platelets remains unknown. We show that Cbl-b is expressed in human platelets along with c-Cbl, but in contrast to c-Cbl, it is not tyrosine-phosphorylated upon glycoprotein VI (GPVI) stimulation. Cbl-b, unlike c-Cbl, is not required for Syk ubiquitylation downstream of GPVI activation. Phospholipase Cgamma2 (PLCgamma2) and Bruton's tyrosine kinase (BTK) are constituently associated with Cbl-b. Cbl-b-deficient (Cbl-b(-/-)) platelets display an inhibition in the concentration-response curve for GPVI-specific agonist-induced aggregation, secretion, and Ca(2+) mobilization. A parallel inhibition is found for activation of PLCgamma2 and BTK. However, Syk activation is not affected by the absence of Cbl-b, indicating that Cbl-b acts downstream of Syk but upstream of BTK and PLCgamma2. When Cbl-b(-/-) mice were tested in the ferric chloride thrombosis model, occlusion time was increased and clot stability was reduced compared with wild type controls. These data indicate that Cbl-b plays a positive modulatory role in GPVI-dependent platelet signaling, which translates to an important regulatory role in hemostasis and thrombosis in vivo.
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Affiliation(s)
- James L Daniel
- Department of Anatomy, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, Pennsylvania 19140, USA.
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15
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Abstract
Recent studies have demonstrated that a number of E3 ubiquitin ligases, including Cbl, Smurf1, Smurf2, HDM2, BCA2, SCF(beta-TRCP) and XRNF185, play important roles in cell adhesion and migration. Cbl negatively regulates cell adhesion via alpha integrin and Rap1 and inhibits actin polymerization by ubiquitinating mDab1 and WAVE2. Smurf1 regulates cell migration through ubiquitination of RhoA, talin head domain and hPEM2, while Smurf2 ubiquitinates Smurf1, TGFbeta type I receptor and RaplB to modulate cell migration and adhesion. HDM2 negatively regulates cell migration by targeting NFAT (a transcription factor) for ubiquitination and degradation, while SCF(beta-TRCP) ubiquitinates Snail (a transcriptional repressor of E-cadherin) to inhibit cell migration. TRIM32 promotes cell migration through ubiquitination of Abl interactor 2 (Abi2), a tumor suppressor. RNF5 and XRNF185 modulate cell migration by ubiquitinating paxillin. Thus, these E3 ubiquitin ligases regulate cell adhesion and (or) migration through ubiquitination of their specific substrates.
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Affiliation(s)
- Cai Huang
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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16
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Abstract
The highly controlled degradation of proteins via the ubiquitin-proteasome pathway represents a key mechanism for cell regulation and homeostasis. Ubiquitin-dependent proteolysis, carried out in large part by the E3 ubiquitin ligases, is a critical mode of post-translational modification that is important in regulation of cell cycle progression, signal transduction, gene transcription, antigen receptor signaling, immune response and cell differentiation. Recent studies demonstrate that increasing numbers of proteins with ubiquitin ligase activity are being characterized. Identification and characterization of their substrates indicate that they regulate the turnover of key cell cycle proteins (p27Kip1, p21Cip1, p57Kip2, cyclin E), tumor suppressor proteins (p53, RB), signaling kinases (Src, Zap70, PI-3 kinase), apoptosis regulators (Bcl-2, Bax, Bik) and transcription factors (Myc, NF-kappaB, E1F1), all of which have been implicated in the pathogenesis of malignant lymphoma. Studies to determine the functional role of ubiquitin ligases in the pathogenesis of malignant lymphoma represent potential areas of investigation.
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Affiliation(s)
- Megan S Lim
- Division of Anatomic Pathology, Department of Pathology, University of Utah, Salt Lake City, Utah 84132, USA.
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17
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Ligand-induced EpoR internalization is mediated by JAK2 and p85 and is impaired by mutations responsible for primary familial and congenital polycythemia. Blood 2009; 113:5287-97. [PMID: 19336760 DOI: 10.1182/blood-2008-09-179572] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epo-induced endocytosis of EpoR plays important roles in the down-regulation of EpoR signaling and is the primary means that regulates circulating Epo concentrations. Here we show that cell-surface EpoR is internalized via clathrin-mediated endocytosis. Both JAK2 kinase activity and EpoR cytoplasmic tyrosines are important for ligand-dependent EpoR internalization. Phosphorylated Y429, Y431, and Y479 in the EpoR cytoplasmic domain bind p85 subunit of PI3 kinase on Epo stimulation and individually are sufficient to mediate Epo-dependent EpoR internalization. Knockdown of p85alpha and p85beta or expression of their dominant-negative forms, but not inhibition of PI3 kinase activity, dramatically impaired EpoR internalization, indicating that p85alpha and p85beta may recruit proteins in the endocytic machinery on Epo stimulation. Furthermore, mutated EpoRs from primary familial and congenital polycythemia (PFCP) patients lacking the 3 important tyrosines do not bind p85 or internalize on stimulation. Addition of residues encompassing Y429 and Y431 to these truncated receptors restored p85beta binding and Epo sensitivity. Our results identify a novel PI3 kinase activity-independent function of p85 in EpoR internalization and support a model that defects of internalization in truncated EpoRs from PFCP patients contribute to Epo hypersensitivity and prolonged signaling.
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18
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Bankers-Fulbright JL, Bartemes KR, Kephart GM, Kita H, O'Grady SM. Beta2-integrin-mediated adhesion and intracellular Ca2+ release in human eosinophils. J Membr Biol 2009; 228:99-109. [PMID: 19290459 DOI: 10.1007/s00232-009-9163-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 02/18/2009] [Indexed: 01/13/2023]
Abstract
Human eosinophils spontaneously adhere to various substrates in the absence of exogenously added activators. In the present study a method was developed for characterizing eosinophil adhesion by measuring changes in impedance. Impedance measurements were performed in HCO(3)-buffered HybriCare medium maintained in a humidified 5% CO(2) incubator at 37 degrees C. Impedance increased by more than 1 kOmega within minutes after eosinophils made contact with the substrate, reaching a peak within 20 min. Blocking mobilization of intracellular [Ca(2+)] that precedes adhesion with BAPTA-AM (10 microM) completely inhibited the rise in impedance as well as the changes in cell shape typically observed in adherent cells. However, lowering the extracellular [Ca(2+)] with 2.5 mM EGTA did not inhibit the increase in impedance. Pretreatment with anti-CD18 antibody to block substrate interactions with beta(2)-integrins, or jasplakinolide (2 microM) to block actin reorganization, abolished the increase in impedance and adherent morphology of the cells. Exposure of eosinophils to the phosphatidylinositol 3 kinase inhibitor LY294002 (5 microM) or treatment with protein kinase C zeta pseudosubstrate to competitively inhibit activity of the enzyme significantly reduced the increase in impedance and inhibited the cell spreading associated with adhesion. These results demonstrate a novel method for measuring eosinophil adhesion and showed that, following formation of a tethered attachment, a rapid increase in intracellular [Ca(2+)] precedes the cytoskeletal rearrangements required for cell shape changes and plasma membrane-substrate interactions associated with adhesion.
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19
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Shen M, Yen A. c-Cbl interacts with CD38 and promotes retinoic acid-induced differentiation and G0 arrest of human myeloblastic leukemia cells. Cancer Res 2008; 68:8761-9. [PMID: 18974118 DOI: 10.1158/0008-5472.can-08-1058] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Retinoic acid (RA) is known to regulate cell growth and differentiation. In HL-60 human myeloblastic leukemia cells, it causes mitogen-activated protein kinase (MAPK) signaling leading to myeloid differentiation and G(0) cell cycle arrest. This communication reports that expression of the Cbl adaptor caused enhanced extracellular signal-regulated kinase 2 activation and promoted RA-induced differentiation and G(0)-arrest. Stable transfectants ectopically expressing c-Cbl underwent myeloid differentiation faster than wild-type (wt) cells when treated with RA. In contrast, c-Cbl knockdown stable transfectants differentiated slower than wt cells when treated with RA. Cells ectopically expressing c-Cbl had enhanced CD38 expression when treated with RA, and cells ectopically expressing CD38 had enhanced c-Cbl expression, even without with RA, suggesting an interaction between c-Cbl and CD38. Fluorescence resource energy transfer and coimmunoprecipitation showed that c-Cbl and CD38 bind each other. RA causes the gradual down-regulation and eventual loss of c-Cbl expression, resulting in loss of the Cbl-CD38 interaction, suggesting that c-Cbl plays a relatively early role in promoting RA-induced differentiation. RA-induced differentiation can thus be propelled by c-Cbl and by CD38, both of which bind together, enhance the expression of each other, and cause MAPK signaling. There thus seems to be a cooperative role for c-Cbl and CD38, reflected in their direct binding, in propulsion of RA-induced differentiation.
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Affiliation(s)
- Miaoqing Shen
- Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853, USA
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20
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Methi T, Berge T, Torgersen KM, Taskén K. Reduced Cbl phosphorylation and degradation of the zeta-chain of the T-cell receptor/CD3 complex in T cells with low Lck levels. Eur J Immunol 2008; 38:2557-63. [PMID: 18792408 DOI: 10.1002/eji.200737837] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
T cells with short interfering RNA-mediated Lck-knockdown (kd) display paradoxical hyper-responsiveness upon TCR ligation. We have previously reported a possible mechanism for T-cell activation in cells with low levels of Lck depending on Grb2-SOS1 recruitment to the zeta-chain of TCR/CD3 (Methi et al., Eur. J. Immunol. 2007, 37: 2539-2548). Here, we show that short interfering RNA-mediated targeting of Lck caused a dramatic reduction in c-Cbl phosphorylation and a general reduction in protein ubiquitination after TCR stimulation. Specifically, this resulted in reduced ubiquitination of the zeta-chain, yet internalization of TCR/CD3 appeared to be normal after receptor engagement. However, zeta-chain levels were elevated in Lck-kd cells, and confocal microscopy revealed reduced colocalization of CD3-containing vesicles with endosomal and lysosomal compartments. We hypothesize that prolonged stability of internalized T-cell receptor complex may result in extended signaling in T cells with low Lck levels.
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Affiliation(s)
- Trond Methi
- The Biotechnology Centre of Oslo and Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Oslo, Norway
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21
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Yang B, Gay DL, MacLeod MKL, Cao X, Hala T, Sweezer EM, Kappler J, Marrack P, Oliver PM. Nedd4 augments the adaptive immune response by promoting ubiquitin-mediated degradation of Cbl-b in activated T cells. Nat Immunol 2008; 9:1356-63. [PMID: 18931680 DOI: 10.1038/ni.1670] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 09/30/2008] [Indexed: 11/09/2022]
Abstract
Nedd4 and Itch are E3 ubiquitin ligases that ubiquitinate similar targets in vitro and thus are thought to function similarly. T cells lacking Itch show spontaneous activation and T helper type 2 polarization. To test whether loss of Nedd4 affects T cells in the same way, we generated Nedd4(+/+) and Nedd4(-/-) fetal liver chimeras. Nedd4(-/-) T cells developed normally but proliferated less, produced less interleukin 2 and provided inadequate help to B cells. Nedd4(-/-) T cells contained more of the E3 ubiquitin ligase Cbl-b, and Nedd4 was required for polyubiquitination of Cbl-b induced by CD28 costimulation. Our data demonstrate that Nedd4 promotes the conversion of naive T cells into activated T cells. We propose that Nedd4 and Itch ubiquitinate distinct target proteins in vivo.
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Affiliation(s)
- Baoli Yang
- Department of Obstetrics and Gynecology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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22
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Nolz JC, Nacusi LP, Segovis CM, Medeiros RB, Mitchell JS, Shimizu Y, Billadeau DD. The WAVE2 complex regulates T cell receptor signaling to integrins via Abl- and CrkL-C3G-mediated activation of Rap1. ACTA ACUST UNITED AC 2008; 182:1231-44. [PMID: 18809728 PMCID: PMC2542481 DOI: 10.1083/jcb.200801121] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
WAVE2 regulates T cell receptor (TCR)–stimulated actin cytoskeletal dynamics leading to both integrin clustering and affinity maturation. Although WAVE2 mediates integrin affinity maturation by recruiting vinculin and talin to the immunological synapse in an Arp2/3-dependent manner, the mechanism by which it regulates integrin clustering is unclear. We show that the Abl tyrosine kinase associates with the WAVE2 complex and TCR ligation induces WAVE2-dependent membrane recruitment of Abl. Furthermore, we show that WAVE2 regulates TCR-mediated activation of the integrin regulatory guanosine triphosphatase Rap1 via the recruitment and activation of the CrkL–C3G exchange complex. Moreover, we demonstrate that although Abl does not regulate the recruitment of CrkL–C3G into the membrane, it does affect the tyrosine phosphorylation of C3G, which is required for its guanine nucleotide exchange factor activity toward Rap1. This signaling node regulates not only TCR-stimulated integrin clustering but also affinity maturation. These findings identify a previously unknown mechanism by which the WAVE2 complex regulates TCR signaling to Rap1 and integrin activation.
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Affiliation(s)
- Jeffrey C Nolz
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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23
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O'Shea JJ, Johnston JA, Kehrl J, Koretzky G, Samelson LE. Key molecules involved in receptor-mediated lymphocyte activation. ACTA ACUST UNITED AC 2008; Chapter 11:Unit 11.9A. [PMID: 18432708 DOI: 10.1002/0471142735.im1109as44] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This unit, along with Unit 11.9B, provides a summary of our current knowledge about various signaling pathways critical to the function of immune cells. Here, our understanding of T cell receptor (TCR)- and B cell receptor (BCR)-mediated signaling is summarized. A schematic representation of immunologically relevant cytokine receptors and the Janus Family Kinases (JAKs) that is activated through these receptors is provided, along with details about molecules involved in interleukin 2 mediated signal transduction.
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Affiliation(s)
- J J O'Shea
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, Maryland, USA
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24
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Loeser S, Penninger JM. Regulation of peripheral T cell tolerance by the E3 ubiquitin ligase Cbl-b. Semin Immunol 2007; 19:206-14. [PMID: 17391982 DOI: 10.1016/j.smim.2007.02.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 02/16/2007] [Indexed: 02/07/2023]
Abstract
The family of the Casitas B-lineage Lymphoma (Cbl) proteins, c-Cbl, Cbl-b, and Cbl-3, function as E3 ubiquitin ligases and molecular adaptors. In particular, Cbl-b acts as a gatekeeper in T cell activation that controls activation thresholds and the requirement for co-stimulation. Loss of Cbl-b expression renders animals susceptible to antigen-triggered autoimmunity suggesting that Cbl-b is a key autoimmunity gene. In addition, Cbl-b plays a critical role in T cell anergy and escape from regulatory T cells (Treg) suppression. Modulation of Cbl-b might provide us with a unique opportunity for future immune treatment of human disorders such as autoimmunity, immunodeficiency, or cancer.
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Affiliation(s)
- Stefanie Loeser
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohrgasse 3, A-1030 Vienna, Austria.
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25
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Li N, Lorinczi M, Ireton K, Elferink LA. Specific Grb2-mediated interactions regulate clathrin-dependent endocytosis of the cMet-tyrosine kinase. J Biol Chem 2007; 282:16764-75. [PMID: 17449471 DOI: 10.1074/jbc.m610835200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysosomal degradation of the receptor-tyrosine kinase cMet requires receptor ubiquitination by the E3 ubiquitin ligase Cbl followed by clathrin-dependent internalization. A role for Cbl as an adaptor for cMet internalization has been previously reported. However, the requirement for Cbl ubiquitin ligase activity in this process and its mode of recruitment to cMet has yet to be determined. Cbl can directly bind cMet at phosphotyrosine 1003 or indirectly via Grb2 to phosphotyrosine 1356 in the multisubstrate binding domain of cMet. The direct binding of Cbl with cMet is critical for receptor degradation and not receptor internalization. Here we show a strict requirement for Grb2 and the ubiquitin ligase activity of Cbl for cMet endocytosis. Receptor internalization was impaired by small interfering RNA depletion of Grb2, overexpression of dominant negative Grb2 mutants, and point mutations in the cMet multisubstrate docking site that inhibits the direct association of Grb2 with cMet. The requirement for Grb2 was specific and did not involve the multiadaptor Gab1. cMet internalization was impaired in cells expressing an ubiquitin ligase-deficient Cbl mutant or conjugation-deficient ubiquitin but was unaffected in cells expressing a Cbl mutant that is unable to bind cMet directly. Expression of a Cbl-Grb2 chimera rescued impaired cMet endocytosis in cells depleted of endogenous Grb2. These results indicate that the ubiquitin ligase activity of Cbl is critical for clathrin-dependent cMet internalization and suggest a role for Grb2 as an intermediary linking Cbl ubiquitin ligase activity to this process.
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Affiliation(s)
- Ning Li
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555-1074, USA
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26
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Dragone LL, Myers MD, White C, Gadwal S, Sosinowski T, Gu H, Weiss A. Src-like adaptor protein (SLAP) regulates B cell receptor levels in a c-Cbl-dependent manner. Proc Natl Acad Sci U S A 2006; 103:18202-7. [PMID: 17110436 PMCID: PMC1838730 DOI: 10.1073/pnas.0608965103] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Src-like adaptor protein (SLAP) and c-Cbl recently have been shown to cooperate in regulating T cell receptor (TCR) levels in developing T cells. SLAP also is expressed in developing B cells, and its deficiency leads to alterations in B cell receptor (BCR) levels and B cell development. Hence, we hypothesized that SLAP and c-Cbl may cooperate during B cell development to regulate BCR levels. In mice deficient in both SLAP and c-Cbl, we found that B cell development is altered, suggesting that they function through intersecting pathways. To study the mechanism by which SLAP and c-Cbl alter BCR levels, we coexpressed them in a mature mouse B cell line (Bal-17). First we determined that SLAP associates with proximal components of the BCR complex after stimulation and internalization. Coexpression of SLAP and c-Cbl in Bal-17 led to decreased surface and total BCR levels. This decrease in BCR levels depended on intact Src homology 2 (SH2) and C-terminal domains of SLAP. In addition, a mutation in the SH2 domain of SLAP blocked its colocalization with c-Cbl and the BCR complex, whereas deletion of the C terminus did not affect its localization. Last, coexpression of SLAP and c-Cbl altered BCR complex recycling. This alteration in BCR complex recycling depended on enzymatically active c-Cbl and Src family kinases, as well as the intact SH2 and C-terminal domains of SLAP. These data suggest that SLAP has a conserved function in B and T cells by adapting c-Cbl to the antigen-receptor complex and targeting it for degradation.
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Affiliation(s)
- Leonard L. Dragone
- Division of Pediatric Immunology/Rheumatology, Department of Pediatrics, and
| | - Margaret D. Myers
- Howard Hughes Medical Institute
- Division of Rheumatology, Department of Medicine, and
- Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, CA 94143
| | - Carmen White
- Division of Pediatric Immunology/Rheumatology, Department of Pediatrics, and
| | - Shyam Gadwal
- University of Maryland Baltimore County, Baltimore, MD 21250
| | | | - Hua Gu
- Microbiology Department, Columbia University, College of Physician and Surgeons, New York, NY 10032
| | - Arthur Weiss
- Howard Hughes Medical Institute
- Division of Rheumatology, Department of Medicine, and
- Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, CA 94143
- To whom correspondence should be addressed at:
Howard Hughes Medical Institute, University of California, 513 Parnassus Avenue, Box 0795, San Francisco, CA 94143. E-mail:
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27
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Swaminathan G, Tsygankov AY. The Cbl family proteins: ring leaders in regulation of cell signaling. J Cell Physiol 2006; 209:21-43. [PMID: 16741904 DOI: 10.1002/jcp.20694] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The proto-oncogenic protein c-Cbl was discovered as the cellular form of v-Cbl, a retroviral transforming protein. This was followed over the years by important discoveries, which identified c-Cbl and other Cbl-family proteins as key players in several signaling pathways. c-Cbl has donned the role of a multivalent adaptor protein, capable of interacting with a plethora of proteins, and has been shown to positively influence certain biological processes. The identity of c-Cbl as an E3 ubiquitin ligase unveiled the existence of an important negative regulatory pathway involved in maintaining homeostasis in protein tyrosine kinase (PTK) signaling. Recent years have also seen the emergence of novel regulators of Cbl, which have provided further insights into the complexity of Cbl-influenced pathways. This review will endeavor to provide a summary of current studies focused on the effects of Cbl proteins on various biological processes and the mechanism of these effects. The major sections of the review are as follows: Structure and genomic organization of Cbl proteins; Phosphorylation of Cbl; Interactions of Cbl; Localization of Cbl; Mechanism of effects of Cbl: (a) Ubiquitylation-dependent events: This section elucidates the mechanism of Cbl-mediated downregulation of EGFR and details the PTK and non-PTKs targeted by Cbl. In addition, it addresses the functional requirements for E3 Ubiquitin ligase activity of Cbl and negative regulation of Cbl-mediated downregulation of PTKs, (b) Adaptor functions: This section discusses the mechanisms of adaptor functions of Cbl in mitogen-activated protein kinase (MAPK) activation, insulin signaling, regulation of Ras-related protein 1 (Rap1), PI-3' kinase signaling, and regulation of Rho-family GTPases and cytoskeleton; Biological functions: This section gives an account of the diverse biological functions of Cbl and includes the role of Cbl in transformation, T-cell signaling and thymus development, B-cell signaling, mast-cell degranulation, macrophage functions, bone development, neurite growth, platelet activation, muscle degeneration, and bacterial invasion; Conclusions and perspectives.
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Affiliation(s)
- Gayathri Swaminathan
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
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28
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Rudd ML, Tua-Smith A, Straus DB. Lck SH3 domain function is required for T-cell receptor signals regulating thymocyte development. Mol Cell Biol 2006; 26:7892-900. [PMID: 16923964 PMCID: PMC1636743 DOI: 10.1128/mcb.00968-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thymocyte development is shaped by signals from the T-cell antigen receptor. The strength of receptor signaling determines developmental progression as well as deletion of self-reactive T cells. Receptor stimulation of the extracellular signal-regulated kinase (ERK) pathway plays an important regulatory role during thymocyte development. However, it is unclear how differences in receptor signaling are translated into distinctive activation of the ERK pathway. We have investigated the potential role of the Lck tyrosine kinase in regulating intracellular signaling during thymocyte development. While Lck is known to be critical for initial T-cell receptor signaling events, it may have an independent role in regulating intracellular signaling through the function of its SH3 domain. To determine whether such a regulatory mechanism functions during thymocyte development, we generated mice in which the normal lck allele is replaced with an lck SH3 domain mutant. Analysis of these mice revealed that both early thymocyte development and maturation of CD4(+) and CD8(+) lineages is impaired. Investigation of thymocyte responses to antigen receptor stimulation showed a significant reduction in proliferation and ERK pathway activation, although initial signaling events were intact. These findings indicate that Lck SH3 domain function may provide a means to independently couple receptor signaling to regulation of the ERK pathway during thymocyte development.
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Affiliation(s)
- Meghan L Rudd
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA
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29
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Chemnitz JM, Lanfranco AR, Braunstein I, Riley JL. B and T Lymphocyte Attenuator-Mediated Signal Transduction Provides a Potent Inhibitory Signal to Primary Human CD4 T Cells That Can Be Initiated by Multiple Phosphotyrosine Motifs. THE JOURNAL OF IMMUNOLOGY 2006; 176:6603-14. [PMID: 16709818 DOI: 10.4049/jimmunol.176.11.6603] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The B and T lymphocyte attenuator (BTLA) is a recently identified member of the CD28 family of cell receptors. Initial reports demonstrated that mice deficient in BTLA expression were more susceptible to experimental autoimmune encephalomyelitis, indicating that BTLA was likely to function as a negative regulator of T cell activation. However, cross-linking of BTLA only resulted in a 2-fold reduction of IL-2 production, questioning the potency with which BTLA engagement blocks T cell activation. We established a model in which BTLA signaling could be studied in primary human CD4 T cells. We observed that cross-linking of a chimeric receptor consisting of the murine CD28 extracellular domain and human BTLA cytoplasmic tail potently inhibits IL-2 production and completely suppresses T cell expansion. Mutation of any BTLA tyrosine motifs had no effect on the ability of BTLA to block T cell activation. Only mutation of all four tyrosines rendered the BTLA cytoplasmic tail nonfunctional. We performed structure-function studies to determine which factors recruited to the BTLA cytoplasmic tail correlated with BTLA function. Using pervanadate as a means to phosphorylate the BTLA cytoplasmic tail, we observed both Src homology protein (SHP)-1 and SHP-2 recruitment. However, upon receptor engagement, we observed only SHP-1 recruitment, and mutations that abrogated SHP-1 recruitment did not impair BTLA function. These studies question whether SHP-1 or SHP-2 have any role in BTLA function and caution against the use of pervanadate as means to initiate signal transduction cascades in primary cells.
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Affiliation(s)
- Jens M Chemnitz
- Abramson Family Cancer Research Institute and Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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30
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Thien C, Langdon W. c-Cbl and Cbl-b ubiquitin ligases: substrate diversity and the negative regulation of signalling responses. Biochem J 2006; 391:153-66. [PMID: 16212556 PMCID: PMC1276912 DOI: 10.1042/bj20050892] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The activation of signalling pathways by ligand engagement with transmembrane receptors is responsible for determining many aspects of cellular function and fate. While these outcomes are initially determined by the nature of the ligand and its receptor, it is also essential that intracellular enzymes, adaptor proteins and transcription factors are correctly assembled to convey the intended response. In recent years, it has become evident that proteins that regulate the amplitude and duration of these signalling responses are also critical in determining the function and fate of cells. Of these, the Cbl family of E3 ubiquitin ligases and adaptor proteins has emerged as key negative regulators of signals from many types of cell-surface receptors. The array of receptors and downstream signalling proteins that are regulated by Cbl proteins is diverse; however, in most cases, the receptors have a common link in that they either possess a tyrosine kinase domain or they form associations with cytoplasmic PTKs (protein tyrosine kinases). Thus Cbl proteins become involved in signalling responses at a time when PTKs are first activated and therefore provide an initial line of defence to ensure that signalling responses proceed at the desired intensity and duration.
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Affiliation(s)
- Christine B. F. Thien
- School of Surgery and Pathology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Correspondence may be addressed to either author (email or )
| | - Wallace Y. Langdon
- School of Surgery and Pathology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Correspondence may be addressed to either author (email or )
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31
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Horne WC, Sanjay A, Bruzzaniti A, Baron R. The role(s) of Src kinase and Cbl proteins in the regulation of osteoclast differentiation and function. Immunol Rev 2006; 208:106-25. [PMID: 16313344 DOI: 10.1111/j.0105-2896.2005.00335.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The osteoclast resorbs mineralized bone during bone development, homeostasis, and repair. The deletion of the gene encoding the nonreceptor tyrosine kinase c-Src produces an osteopetrotic skeletal phenotype that is the consequence of the inability of the mature osteoclast to efficiently resorb bone. Src-/- osteoclasts exhibit reduced motility and abnormal organization of the apical secretory domain (the ruffled border) and attachment-related cytoskeletal elements that are necessary for bone resorption. A key function of Src in osteoclasts is to promote the rapid assembly and disassembly of the podosomes, the specialized integrin-based attachment structures of osteoclasts and other highly motile cells. Once recruited to the activated integrins, especially alphavbeta3), by the adhesion tyrosine kinase Pyk2, Src binds and phosphorylates Cbl and Cbl-b, homologous multisite adapter proteins with ubiquitin ligase activity. The Cbl proteins in turn recruit and activate additional signaling effectors, including phosphatidylinositol 3-kinase and dynamin, which play key roles in the development of cell polarity and the regulation of cell attachment and motility. In addition, Src and the Cbl proteins contribute to signaling cascades that are activated by several important receptors, including receptor activator of nuclear factor kappaB and the macrophage colony-stimulating factor receptor, and also downregulate the signaling from many of these receptors.
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Affiliation(s)
- William C Horne
- Department of Orthopaedics and Rehabilitation and Cell Biology, Yale University School of Medicine, New Haven, CT 06520-8044, USA
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32
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Dragone LL, Myers MD, White C, Sosinowski T, Weiss A. Src-Like Adaptor Protein Regulates B Cell Development and Function. THE JOURNAL OF IMMUNOLOGY 2005; 176:335-45. [PMID: 16365426 DOI: 10.4049/jimmunol.176.1.335] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The avidity of BCRs and TCRs influences signal strength during processes of lymphocyte development. Avidity is determined by both the intrinsic affinity for Ag and surface levels of the Ag receptor. The Src-like adaptor protein (SLAP) is a regulator of TCR levels on thymocytes, and its deficiency alters thymocyte development. We hypothesized that SLAP, which is expressed in B cells, also is important in regulating BCR levels, signal strength, and B cell development. To test this hypothesis, we analyzed the B cell compartment in SLAP-deficient mice. We found increased splenic B cell numbers and decreased surface IgM levels on mature, splenic B cells deficient in SLAP. Immature bone marrow and splenic B cells from BCR-transgenic, SLAP-deficient mice were found to express higher surface levels of IgM. In contrast, mature splenic B cells from BCR-transgenic mice expressed decreased levels of surface BCR associated with decreased calcium flux and activation-induced markers, compared with controls. These data suggest that SLAP regulates BCR levels and signal strength during lymphocyte development.
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Affiliation(s)
- Leonard L Dragone
- Division of Pediatric Immunology/Rheumatology, Department of Pediatrics, University of California, San Francisco, CA 94143, USA
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33
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Samaan A, . EH, . WM. Differential Phosphorylation of c-Cbl in Leukemogenic and Nonleukemogenic HTLV-I Cell Lines. ACTA ACUST UNITED AC 2005. [DOI: 10.3923/ijv.2006.39.49] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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34
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Myers MD, Sosinowski T, Dragone LL, White C, Band H, Gu H, Weiss A. Src-like adaptor protein regulates TCR expression on thymocytes by linking the ubiquitin ligase c-Cbl to the TCR complex. Nat Immunol 2005; 7:57-66. [PMID: 16327786 DOI: 10.1038/ni1291] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 10/05/2005] [Indexed: 11/09/2022]
Abstract
The adaptor molecule SLAP and E3 ubiquitin ligase c-Cbl each regulate expression of T cell receptor (TCR)-CD3 on thymocytes. Here we provide genetic and biochemical evidence that both molecules function in the same pathway. TCR-CD3 expression was similar in the absence of SLAP and/or c-Cbl. SLAP and c-Cbl were found to interact, and their expression together downregulated CD3epsilon. This required multiple domains in SLAP and the ring finger of c-Cbl. Furthermore, expression of SLAP and c-Cbl together induced TCRzeta ubiquitination and degradation, preventing the accumulation of fully assembled recycling TCR complexes. These studies indicate that SLAP links the E3 ligase activity of c-Cbl to the TCR, allowing for stage-specific regulation of TCR expression.
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Affiliation(s)
- Margaret D Myers
- Department of Medicine, Rosalind Russell Medical Research Center for Arthritis, Howard Hughes Medical Institute, University of California San Francisco, 94143, USA
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35
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Yang P, Henderson AJ. Nef enhances c-Cbl phosphorylation in HIV-infected CD4+ T lymphocytes. Virology 2005; 336:219-28. [PMID: 15892963 DOI: 10.1016/j.virol.2005.03.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Revised: 12/16/2004] [Accepted: 03/21/2005] [Indexed: 10/25/2022]
Abstract
The multifunctional HIV-1 protein Nef possesses several motifs that interact with signaling molecules in infected T cells. In order to determine whether Nef influences T cell activation, cells were infected with Nef-positive and Nef-negative clones of HIV. CD28 expression and changes in tyrosine phosphorylation were monitored. We observed no Nef-dependent changes in CD28 expression or function. However, infection with Nef-positive virus led to changes in tyrosine phosphorylation. This Nef-induced phosphorylation was observed in unstimulated cells, and c-Cbl was identified as one of the proteins whose phosphorylation was upregulated by Nef. Furthermore, Lck is required for Nef-mediated c-Cbl tyrosine phosphorylation. These results suggest that Nef modifies T cell signaling in the absence of T cell receptor engagement and co-stimulation.
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Affiliation(s)
- Polung Yang
- Integrated Bioscience Graduate Program in Immunobiology, Department of Veterinary Science, Immunology Research Laboratories, 115 Henning Building, Pennsylvania State University, University Park, PA 16802, USA
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36
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Affiliation(s)
- Simrit Parmar
- Robert H Lurie Comprehensive Cancer Center, Division of Hematology-Onocology, Northwestern University Medical School, Chicago, IL, USA
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37
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Teckchandani AM, Panetti TS, Tsygankov AY. c-Cbl regulates migration of v-Abl-transformed NIH 3T3 fibroblasts via Rac1. Exp Cell Res 2005; 307:247-58. [PMID: 15922744 DOI: 10.1016/j.yexcr.2005.03.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Revised: 03/11/2005] [Accepted: 03/11/2005] [Indexed: 01/06/2023]
Abstract
Cellular events like cell adhesion and migration involve complex rearrangements of the actin cytoskeleton. We have previously shown that the multidomain adaptor protein c-Cbl facilitates actin cytoskeletal reorganizations that result in the adhesion of v-Abl-transformed NIH 3T3 fibroblasts. In this report, we demonstrate that c-Cbl also enhances migration of v-Abl-transformed NIH 3T3 fibroblasts. This effect of c-Cbl depends on its tyrosine phosphorylation, specifically on phosphorylation of its Tyr-731, which is required for binding of PI-3' kinase to c-Cbl. Furthermore, we demonstrate that the effect of c-Cbl on migration of v-Abl-transformed fibroblasts is mediated by active PI-3' kinase and the small GTPase Rac1. Our results also indicate that ubiquitin ligase activity of c-Cbl is required, while spatial localization of c-Cbl to the pseudopodia is not required for the observed effects of c-Cbl on cell migration.
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Affiliation(s)
- Anjali M Teckchandani
- Department of Microbiology and Immunology, Temple University School of Medicine, 3400 N. Broad Street, Philadelphia, PA 19140, USA
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38
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Machida K, Mayer BJ. The SH2 domain: versatile signaling module and pharmaceutical target. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1747:1-25. [PMID: 15680235 DOI: 10.1016/j.bbapap.2004.10.005] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Revised: 09/29/2004] [Accepted: 10/11/2004] [Indexed: 10/26/2022]
Abstract
The Src homology 2 (SH2) domain is the most prevalent protein binding module that recognizes phosphotyrosine. This approximately 100-amino-acid domain is highly conserved structurally despite being found in a wide variety proteins. Depending on the nature of neighboring protein module(s), such as catalytic domains and other protein binding domains, SH2-containing proteins play many different roles in cellular protein tyrosine kinase (PTK) signaling pathways. Accumulating evidence indicates SH2 domains are highly versatile and exhibit considerable flexibility in how they bind to their ligands. To illustrate this functional versatility, we present three specific examples: the SAP, Cbl and SOCS families of SH2-containing proteins, which play key roles in immune responses, termination of PTK signaling, and cytokine responses. In addition, we highlight current progress in the development of SH2 domain inhibitors designed to antagonize or modulate PTK signaling in human disease. Inhibitors of the Grb2 and Src SH2 domains have been extensively studied, with the aim of targeting the Ras pathway and osteoclastic bone resorption, respectively. Despite formidable difficulties in drug design due to the lability and poor cell permeability of negatively charged phosphorylated SH2 ligands, a variety of structure-based strategies have been used to reduce the size, charge and peptide character of such ligands, leading to the development of high-affinity lead compounds with potent cellular activities. These studies have also led to new insights into molecular recognition by the SH2 domain.
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Affiliation(s)
- Kazuya Machida
- Raymond and Beverly Sackler Laboratory of Genetics and Molecular Medicine, Department of Genetics and Developmental Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3301, USA.
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39
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Zhang J, Chiang YJ, Hodes RJ, Siraganian RP. Inactivation of c-Cbl or Cbl-b differentially affects signaling from the high affinity IgE receptor. THE JOURNAL OF IMMUNOLOGY 2004; 173:1811-8. [PMID: 15265912 DOI: 10.4049/jimmunol.173.3.1811] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Cbl family of proteins negatively regulate signaling from tyrosine kinase-coupled receptors. Among the three members of this family, only c-Cbl and Cbl-b are expressed in hemopoietic cells. To examine the role of c-Cbl and Cbl-b in Fc epsilon RI signaling, mast cell cultures from wild-type, c-Cbl(-/-), and Cbl-b(-/-) mice were generated. Cell growth rates and cell surface expression of Fc epsilon RI were similar in the different cell populations. Compared with control cells, Cbl-b inactivation resulted in increases in Fc epsilon RI-induced Ca(2+) response and histamine release. Fc epsilon RI-induced tyrosine phosphorylation of total cellular proteins, Syk, and phospholipase C-gamma was also enhanced by Cbl-b deficiency, whereas receptor-initiated phosphorylation of Vav, JNK, and p38 kinases was not changed in these cells. In contrast to Cbl-b, c-Cbl deficiency had no detectable effect on Fc epsilon RI-induced histamine release or on the phosphorylation of total cellular proteins or Syk. The absence of c-Cbl increased the phosphorylation of ERK after receptor stimulation, but resulted in slightly reduced p38 phosphorylation and Ca(2+) response. These results suggest that Cbl-b and c-Cbl have divergent effects on Fc epsilon RI signal transduction and that Cbl-b, but not c-Cbl, functions as a negative regulator of Fc epsilon RI-induced degranulation.
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Affiliation(s)
- Juan Zhang
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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40
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Xing L, Donlin LT, Miller RH, Alexandropoulos K. The adapter molecule Sin regulates T-cell-receptor-mediated signal transduction by modulating signaling substrate availability. Mol Cell Biol 2004; 24:4581-92. [PMID: 15121874 PMCID: PMC400453 DOI: 10.1128/mcb.24.10.4581-4592.2004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Engagement of the T-cell receptor (TCR) results in the activation of a multitude of signaling events that regulate the function of T lymphocytes. These signaling events are in turn modulated by adapter molecules, which control the final functional output through the formation of multiprotein complexes. In this report, we identified the adapter molecule Sin as a new regulator of T-cell activation. We found that the expression of Sin in transgenic T lymphocytes and Jurkat T cells inhibited interleukin-2 expression and T-cell proliferation. This inhibitory effect was specific and was due to defective phospholipase C-gamma (PLC-gamma) phosphorylation and activation. In contrast to other adapters that become phosphorylated upon TCR stimulation, Sin was constitutively phosphorylated in resting cells by the Src kinase Fyn and bound to signaling intermediates, including PLC-gamma. In stimulated cells, Sin was transiently dephosphorylated, which coincided with transient dissociation of Fyn and PLC-gamma. Downregulation of Sin expression using Sin-specific short interfering RNA oligonucleotides inhibited transcriptional activation in response to TCR stimulation. Our results suggest that endogenous Sin influences T-lymphocyte signaling by sequestering signaling substrates and regulating their availability and/or activity in resting cells, while Sin is required for targeting these intermediates to the TCR for fast signal transmission during stimulation.
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Affiliation(s)
- Luzhou Xing
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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41
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Gaston I, Johnson KJ, Oda T, Bhat A, Reis M, Langdon W, Shen L, Deininger MW, Druker BJ. Coexistence of phosphotyrosine-dependent and -independent interactions between Cbl and Bcr-Abl. Exp Hematol 2004; 32:113-21. [PMID: 14725908 DOI: 10.1016/j.exphem.2003.09.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cbl is one of the major tyrosine-phosphorylated proteins in Bcr-Abl-expressing cells. A direct association between the SH2 domain of Bcr-Abl and tyrosine-phosphorylated Cbl has been demonstrated. The purpose of this study was to determine if and how unphosphorylated Cbl and Bcr-Abl may associate. Interactions between Cbl and Bcr-Abl were investigated in yeast two- and three-hybrid systems, gel overlay assays, and immunoprecipitates from mammalian cells expressing wild-type and the Y177F mutant of Bcr-Abl. No direct interaction between Bcr-Abl and unphosphorylated Cbl was observed. Bcr-Abl did, however, associate with Grb2, an adaptor protein that binds tyrosine 177 of Bcr-Abl. Additionally, Grb2 interacted with Cbl. In a yeast three-hybrid assay, Grb2 mediated an interaction between Cbl and Bcr-Abl that was dependent on a functional Grb2 binding site. This interaction was confirmed in vitro using purified proteins. In cells expressing Bcr-Abl with a mutation in the Grb2 binding site, binding of Cbl to Bcr-Abl was significantly reduced, but Cbl tyrosine phosphorylation was maintained. Imatinib treatment of these cells further reduced but did not abrogate Cbl binding, reflecting residual kinase activity. Multiple phosphotyrosine-dependent and -independent interactions stabilize the interaction between Cbl and Abl. Grb2 or another, yet unidentified, protein may mediate an initial interaction between Cbl and Bcr-Abl that is independent of Cbl tyrosine phosphorylation. Following this initial interaction, Cbl can then become tyrosine phosphorylated and interact with the SH2 domain of Bcr-Abl, further stabilizing the complex.
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Affiliation(s)
- Isabelle Gaston
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, Ore. 97239, USA
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42
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Dinulescu DM, Wood LJ, Shen L, Loriaux M, Corless CL, Gross AW, Ren R, Deininger MWN, Druker BJ. c-CBL is not required for leukemia induction by Bcr-Abl in mice. Oncogene 2003; 22:8852-60. [PMID: 14654781 DOI: 10.1038/sj.onc.1206892] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bcr-Abl tyrosine kinase activity is essential for the pathogenesis of chronic myeloid leukemia (CML). A number of Bcr-Abl substrates have been identified, but it is not clear which of these substrates are required for Bcr-Abl to transform cells. The multifunctional protein c-Cbl is one of the most prominently tyrosine-phosphorylated proteins in Bcr-Abl-expressing cells. Using cell lines and mice with homozygous disruption of the c-CBL locus, we investigated the role of this protein for Bcr-Abl-driven transformation. We find that although c-Cbl(-/-) fibroblast cell lines show a deficit in Bcr-Abl transformation compared to wild-type (Wt) cells, this deficit was less pronounced in c-Cbl(-/-) B cells derived from murine bone marrow. Most importantly, in a transplantation model of CML, Bcr-Abl was capable of inducing fatal leukemia in mice in the absence of c-Cbl protein. Our results indicate that c-Cbl is dispensable for Bcr-Abl-induced leukemogenesis in mice.
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43
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Niederberger N, Holmberg K, Alam SM, Sakati W, Naramura M, Gu H, Gascoigne NRJ. Allelic exclusion of the TCR alpha-chain is an active process requiring TCR-mediated signaling and c-Cbl. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:4557-63. [PMID: 12707333 DOI: 10.4049/jimmunol.170.9.4557] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phenotypic allelic exclusion at the TCRalpha locus is developmentally regulated in thymocytes. Many immature thymocytes express two cell surface alpha-chain species. Following positive selection, the vast majority of mature thymocytes and peripheral T cells display a single cell surface alpha-chain. A posttranslational mechanism occurring at the same time as positive selection and TCR up-regulation leads to this phenotypic allelic exclusion. Different models have been proposed to explain the posttranslational regulation of the alpha-chain allelic exclusion. In this study, we report that allelic exclusion is not regulated by competition between distinct alpha-chains for a single beta-chain, as proposed by the dueling alpha-chain model, nor by limiting CD3 zeta-chain in mature TCR(high) thymocytes. Our data instead favor the selective retention model where the positive selection signal through the TCR leads to phenotypic allelic exclusion by specifically maintaining cell surface expression of the selected alpha-chain while the nonselected alpha-chain is internalized. The use of inhibitors specific for Lck and/or other Src kinases indicates a role for these protein tyrosine kinases in the signaling events leading to the down-regulation of the nonselectable alpha-chain. Loss of the ubiquitin ligase/TCR signaling adapter molecule c-Cbl, which is important in TCR down-modulation and is a negative regulator of T cell signaling, leads to increased dual alpha-chain expression on the cell surface of double-positive thymocytes. Thus, not only is there an important role for TCR signaling in causing alpha-chain allelic exclusion, but differential ubiquitination by c-Cbl may be an important factor in causing only the nonselected alpha-chain to be down-modulated.
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MESH Headings
- Alleles
- Animals
- Antibody Affinity/genetics
- Binding, Competitive/genetics
- Binding, Competitive/immunology
- Cross-Linking Reagents/metabolism
- Dimethyl Sulfoxide/pharmacology
- Down-Regulation/drug effects
- Down-Regulation/genetics
- Down-Regulation/immunology
- Fetus
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/immunology
- Genes, T-Cell Receptor alpha
- Genes, T-Cell Receptor beta
- Immune Sera/metabolism
- Immunophenotyping
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/antagonists & inhibitors
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/biosynthesis
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/physiology
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Mice, Transgenic
- Organ Culture Techniques
- Proto-Oncogene Proteins/deficiency
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/physiology
- Proto-Oncogene Proteins c-cbl
- Pyrazoles/pharmacology
- Pyrimidines/pharmacology
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell, alpha-beta/antagonists & inhibitors
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Signal Transduction/drug effects
- Signal Transduction/genetics
- Signal Transduction/immunology
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Ubiquitin-Protein Ligases
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44
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Pullar CE, Morris PJ, Wood KJ. Altered proximal T-cell receptor signalling events in mouse CD4+ T cells in the presence of anti-CD4 monoclonal antibodies: evidence for reduced phosphorylation of Zap-70 and LAT. Scand J Immunol 2003; 57:333-41. [PMID: 12662296 DOI: 10.1046/j.1365-3083.2003.01241.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Anti-CD4 monoclonal antibodies are potential therapeutic agents for the prevention of autoimmune disease and treatment of rejection after organ transplantation and are capable of both restoring tolerance to self-antigens and inducing tolerance to antigens introduced under the cover of the antibody therapy in vivo. Tolerance to donor alloantigens can be induced in vivo by administering donor alloantigen in combination with either depleting (YTA 3.1) or nondepleting (YTS 177) anti-CD4, 28 days before heart transplantation in the mouse. The effect of anti-CD4 on proximal T-cell receptor (TCR) signalling pathways and proliferation was investigated in vitro and in vivo in the presence and absence of YTA 3.1 or YTS 177. Anti-CD4 was found to perturb proximal signalling events upon TCR/CD3 ligation, resulting in reduced tyrosine phosphorylation of Zap-70 and LAT (linker for activation of T cells) and reduced association of tyrosine-phosphorylated LAT with lck. This ultimately resulted in severely reduced proliferation of the responding CD4+ T cells. The signalling profile of the anti-CD4-treated cells resembled that of anergic T cells. This could be a result of a common mechanism involving perturbation in the formation of the central supramolecular activation cluster of the immunological synapse by impaired recruitment of CD4 and CD28, thereby resulting in severely reduced lck activation.
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Affiliation(s)
- C E Pullar
- Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, Oxford, UK
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45
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Corsois L, Quatannens B, Dumont P, Aumercier M, Defresne MP, Régnier DCL. Association of a new c-Cbl related protein with the very first stages of apoptosis induction. CANCER DETECTION AND PREVENTION 2002; 26:93-104. [PMID: 12102152 DOI: 10.1016/s0361-090x(02)00006-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study investigates the involvement of the c-cbl proto-oncogene during the first stages of the apoptotic process. We have already shown that a c-Cbl aptotosis-related protein of 90 kDa (CARP 90) is detected very rapidly in the cytoplasm as well as in the nucleus of murine thymocytes after hydrocortisone (HC) treatment. We report here that this protein appeared as well after in vivo treatment of mice by gamma-irradiation or injection of anti-CD3 monoclonal antibody, two potent thymic apoptosis inductors, providing a close relationship between the occurrence of apoptosis and the appearance of CARP 90. We showed that CARP 90 and p120(cbl) share numerous epitopes strikingly suggesting that CARP 90 is coded by c-cbl. In addition, KO mice do not sustain CARP 90 appearance. We finally showed that CARP 90 contains N- and C-terminal end epitopes of p120(cbl), which suggests that CARP 90 is an alternative spliced form of c-cbl. This protein was also observed under gamma-irradiation in tissues of different origin, which enlarges the physiological significance of this phenomenon. The very rapid CARP 90 appearance under apoptotic conditions in the nucleus of cells originating in different tissues makes this protein if not a possible new actor of the apoptotic process, at least an interesting marker of this process.
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Affiliation(s)
- Laurent Corsois
- Laboratory of Molecular Oncology, CNRS-UMR 8526, Institut Pasteur de Lille, France
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46
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Tse KF, Allebach J, Levis M, Smith BD, Bohmer FD, Small D. Inhibition of the transforming activity of FLT3 internal tandem duplication mutants from AML patients by a tyrosine kinase inhibitor. Leukemia 2002; 16:2027-36. [PMID: 12357354 DOI: 10.1038/sj.leu.2402674] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2002] [Accepted: 06/03/2002] [Indexed: 11/09/2022]
Abstract
FLT3 is a receptor tyrosine kinase that may play a role in a significant proportion of leukemias. In addition to being aberrantly expressed in acute leukemias, activating mutations of the FLT3 gene have been found in patients with AML, myelodysplastic syndrome (MDS) and more rarely, ALL. Internal tandem duplications (ITDs) of the FLT3 gene have been detected in 17-34% of patients with AML and portend a poor prognosis for these patients. FLT3 receptors containing ITD mutations (FLT3/ITDs) are constitutively activated in the absence of FLT3 ligand (FL) stimulation leading to the activation of downstream signaling proteins, including ERK and STAT 5. FLT3 activity, therefore, is a logical target for therapeutic intervention. AG1296 is a tyrosine kinase inhibitor of the tyrphostin class that shows inhibitory activity for wild-type FLT3, in addition to the PDGF and c-KIT receptors. We examined the inhibitory effects of AG1296 on FLT3/ITDs isolated from AML patients in the IL-3-dependent cell line, Ba/F3, as well as in primary leukemia samples from AML patients. Immunoprecipitation and immunoblotting analyses demonstrated that FLT3/ITDs were constitutively phosphorylated in the absence of FL. The auto-phosphorylation of FLT3/ITDs was inhibited by AG1296 with an IC(50) of approximately 1 microM. FLT3/ITDs were associated with constitutive phosphorylation of ERK, STAT 5A, STAT 5B, CBL, VAV and SHP2 in Ba/F3 cells. The phosphorylation of these downstream signaling molecules was suppressed in a dose-responsive fashion by AG1296. AG1296 inhibited IL-3 independent growth and induced apoptosis in Ba/F3 cells transformed by FLT3/ITDs. AG1296 also inhibited FLT3 auto-phosphorylation, and induced a cytotoxic effect, in primary AML cells. These findings suggest that inhibiting the activity of FLT3 may have a therapeutic value in some leukemias expressing FLT3/ITDs.
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Affiliation(s)
- K-F Tse
- Johns Hopkins University School of Medicine, Department of Oncology Baltimore, MD 21231, USA
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47
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Nishio H, Otsuka M, Kinoshita S, Tokuoka T, Nakajima M, Noda Y, Fukuyama Y, Suzuki K. Phosphorylation of c-Cbl protooncogene product following ethanol administration in rat cerebellum: possible involvement of Fyn kinase. Brain Res 2002; 950:203-9. [PMID: 12231245 DOI: 10.1016/s0006-8993(02)03038-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We have previously shown that ethanol administration results in tyrosine phosphorylation of the 130 kDa protein in rat brain, and identified the protein as Cas, the crk-associated src substrate. In the present study, we demonstrate that Cbl of a 120 kDa protein is also tyrosine-phosphorylated in the cerebellum in response to ethanol administration. We also investigated whether Fyn kinase was involved in ethanol-induced Cbl phosphorylation. Immunoprecipitation experiments showed that the amount of coimmunoprecipitated Fyn kinase with an anti-Cbl antibody increased in extracts from ethanol-administered rats compared to those from saline-administered rats. Exogenous Fyn kinase was shown to phosphorylate on tyrosine residue(s) of Cbl from the cerebellum in vitro. Furthermore, Fyn kinase and Cbl were demonstrated immunohistochemically to be coexpressed in white matter in the cerebellum. These findings indicate that Cbl is tyrosine-phosphorylated in rat cerebellum in response to ethanol administration, and also raise the possibility that Fyn kinase may be involved in the process.
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Affiliation(s)
- Hajime Nishio
- Department of Legal Medicine, Osaka Medical College, 2-7 Daigaku, 569-8686, Takatsuki, Japan
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48
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Kassenbrock CK, Hunter S, Garl P, Johnson GL, Anderson SM. Inhibition of Src family kinases blocks epidermal growth factor (EGF)-induced activation of Akt, phosphorylation of c-Cbl, and ubiquitination of the EGF receptor. J Biol Chem 2002; 277:24967-75. [PMID: 11994282 DOI: 10.1074/jbc.m201026200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Stimulation of T47D cells with epidermal growth factor (EGF) results in the activation of the intrinsic tyrosine kinases of the receptor and the phosphorylation of multiple cellular proteins including the receptor, scaffold molecules such as c-Cbl, adapter molecules such as Shc, and the serine/threonine protein kinase Akt. We demonstrate that EGF stimulation of T47D cells results in the activation of the Src protein-tyrosine kinase and that the Src kinase inhibitor PP1 blocks the EGF-induced phosphorylation of c-Cbl but not the activation/phosphorylation of the EGF receptor itself. PP1 also blocks EGF-induced ubiquitination of the EGF receptor, which is presumably mediated by phosphorylated c-Cbl. Src is associated with c-Cbl, and we have previously demonstrated that the Src-like kinase Fyn can phosphorylate c-Cbl at a preferred binding site for the p85 subunit of phosphatidylinositol 3'-kinase. PP1 treatment blocks EGF-induced activation of the anti-apoptotic protein kinase Akt suggesting that Src may regulate activation of Akt, perhaps by a Src --> c-Cbl --> phosphatidylinositol 3'-kinase --> Akt pathway.
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Affiliation(s)
- C Kenneth Kassenbrock
- Department of Pathology, University of Colorado Health Sciences Center, Denver 80262, USA
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49
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Panigada M, Porcellini S, Barbier E, Hoeflinger S, Cazenave PA, Gu H, Band H, von Boehmer H, Grassi F. Constitutive endocytosis and degradation of the pre-T cell receptor. J Exp Med 2002; 195:1585-97. [PMID: 12070286 PMCID: PMC2193560 DOI: 10.1084/jem.20020047] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The pre-T cell receptor (TCR) signals constitutively in the absence of putative ligands on thymic stroma and signal transduction correlates with translocation of the pre-TCR into glycolipid-enriched microdomains (rafts) in the plasma membrane. Here, we show that the pre-TCR is constitutively routed to lysosomes after reaching the cell surface. The cell-autonomous down-regulation of the pre-TCR requires activation of the src-like kinase p56(lck), actin polymerization, and dynamin. Constitutive signaling and degradation represents a feature of the pre-TCR because the gammadeltaTCR expressed in the same cell line does not exhibit these features. This is also evident by the observation that the protein adaptor/ubiquitin ligase c-Cbl is phosphorylated and selectively translocated into rafts in pre-TCR- but not gammadeltaTCR-expressing cells. A role of c-Cbl-mediated ubiquitination in pre-TCR degradation is supported by the reduction of degradation through pharmacological inhibition of the proteasome and through a dominant-negative c-Cbl ubiquitin ligase as well as by increased pre-TCR surface expression on immature thymocytes in c-Cbl-deficient mice. The pre-TCR internalization contributes significantly to the low surface level of the receptor on developing T cells, and may in fact be a requirement for optimal pre-TCR function.
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Affiliation(s)
- Maddalena Panigada
- Dipartimento di Biologia e Genetica per le Scienze Mediche, Università degli Studi di Milano, Italy
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50
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Inngjerdingen M, Torgersen KM, Maghazachi AA. Lck is required for stromal cell-derived factor 1 alpha (CXCL12)-induced lymphoid cell chemotaxis. Blood 2002; 99:4318-25. [PMID: 12036857 DOI: 10.1182/blood.v99.12.4318] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stromal cell-derived factor 1alpha (CXCL12) induces chemotaxis of lymphocytes through its receptor CXCR4. We examined the role of nonreceptor tyrosine kinases in CXCL12-induced chemotaxis of T cells and natural killer (NK) cells. Damnacanthal, a specific Lck inhibitor, but not the Syk inhibitor piceatannol, inhibited CXCL12-induced chemotaxis of both lymphocyte subsets. Similarly, damnacanthal was shown to inhibit CXCL12-induced chemotaxis of the Jurkat T-cell line. Stimulating T and NK cells with CXCL12 increased both the tyrosine phosphorylation and the kinase activity of Lck. A direct involvement of Lck in CXCL12-induced chemotaxis was demonstrated in the Lck-deficient Jurkat-derived cell line JCaM1.6. Although JCaM1.6 cells express CXCR4, no significant migration was detected after CXCL12 stimulation. Reconstitution with wild-type Lck restored both CXCL12-induced chemotaxis and Lck activation. Furthermore, cotransfection of wild-type Lck with C-terminal Src kinase (Csk) into JCaM1.6 failed to restore the chemotactic response induced by CXCL12. Finally, by targeting critical residues in the Src homology-2 (SH2) or SH3 domains of Lck, we observed that the SH3 domain is important for the function of Lck in CXCL12-mediated chemotaxis. Together, these results suggest a role for Lck in CXCL12-induced signaling pathways leading to lymphocyte chemotaxis.
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Affiliation(s)
- Marit Inngjerdingen
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Norway.
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