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Zhou L, Yang J, Zhang K, Wang T, Jiang S, Zhang X. Rising Star in Immunotherapy: Development and Therapeutic Potential of Small-Molecule Inhibitors Targeting Casitas B Cell Lymphoma-b (Cbl-b). J Med Chem 2024; 67:816-837. [PMID: 38181380 DOI: 10.1021/acs.jmedchem.3c01361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024]
Abstract
Casitas B cell lymphoma-b (Cbl-b) is a vital negative regulator of TCR and BCR signaling pathways, playing a significant role in setting an appropriate threshold for the activation of T cells and controlling the tolerance of peripheral T cells via a variety of mechanisms. Overexpression of Cbl-b leads to immune hyporesponsiveness of T cells. Conversely, the deficiency of Cbl-b in T cells results in markedly increased production of IL-2, even in the lack of CD28 costimulation in vitro. And Cbl-b-/- mice spontaneously reject multifarious cancers. Therefore, Cbl-b may be associated with immune-mediated diseases, and blocking Cbl-b could be considered as a new antitumor immunotherapy strategy. In this review, the possible regulatory mechanisms and biological potential of Cbl-b for antitumor immunotherapy are summarized. Besides, the potential roles of Cbl-b in immune-mediated diseases are comprehensively discussed, with emphasis on Cbl-b immune-oncology agents in the preclinical stage and clinical trials.
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Affiliation(s)
- Lixin Zhou
- Department of Medicinal Chemistry, School of Pharmacy and School of Engineering, China Pharmaceutical University, Nanjing 210009, China
| | - Jiamei Yang
- Department of Medicinal Chemistry, School of Pharmacy and School of Engineering, China Pharmaceutical University, Nanjing 210009, China
| | - Kuojun Zhang
- Department of Medicinal Chemistry, School of Pharmacy and School of Engineering, China Pharmaceutical University, Nanjing 210009, China
| | - Tianyu Wang
- Department of Medicinal Chemistry, School of Pharmacy and School of Engineering, China Pharmaceutical University, Nanjing 210009, China
| | - Sheng Jiang
- Department of Medicinal Chemistry, School of Pharmacy and School of Engineering, China Pharmaceutical University, Nanjing 210009, China
| | - Xiangyu Zhang
- Department of Medicinal Chemistry, School of Pharmacy and School of Engineering, China Pharmaceutical University, Nanjing 210009, China
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2
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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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3
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Structural Dynamics of DPP-4 and Its Influence on the Projection of Bioactive Ligands. Molecules 2018; 23:molecules23020490. [PMID: 29473857 PMCID: PMC6017819 DOI: 10.3390/molecules23020490] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/01/2018] [Accepted: 02/06/2018] [Indexed: 11/17/2022] Open
Abstract
Dipeptidyl peptidase-4 (DPP-4) is a target to treat type II diabetes mellitus. Therefore, it is important to understand the structural aspects of this enzyme and its interaction with drug candidates. This study involved molecular dynamics simulations, normal mode analysis, binding site detection and analysis of molecular interactions to understand the protein dynamics. We identified some DPP-4 functional motions contributing to the exposure of the binding sites and twist movements revealing how the two enzyme chains are interconnected in their bioactive form, which are defined as chains A (residues 40-767) and B (residues 40-767). By understanding the enzyme structure, its motions and the regions of its binding sites, it will be possible to contribute to the design of new DPP-4 inhibitors as drug candidates to treat diabetes.
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Taher TE, Bystrom J, Ong VH, Isenberg DA, Renaudineau Y, Abraham DJ, Mageed RA. Intracellular B Lymphocyte Signalling and the Regulation of Humoral Immunity and Autoimmunity. Clin Rev Allergy Immunol 2017; 53:237-264. [PMID: 28456914 PMCID: PMC5597704 DOI: 10.1007/s12016-017-8609-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
B lymphocytes are critical for effective immunity; they produce antibodies and cytokines, present antigens to T lymphocytes and regulate immune responses. However, because of the inherent randomness in the process of generating their vast repertoire of antigen-specific receptors, B cells can also cause diseases through recognizing and reacting to self. Therefore, B lymphocyte selection and responses require tight regulation at multiple levels and at all stages of their development and activation to avoid diseases. Indeed, newly generated B lymphocytes undergo rigorous tolerance mechanisms in the bone marrow and, subsequently, in the periphery after their migration. Furthermore, activation of mature B cells is regulated through controlled expression of co-stimulatory receptors and intracellular signalling thresholds. All these regulatory events determine whether and how B lymphocytes respond to antigens, by undergoing apoptosis or proliferation. However, defects that alter regulated co-stimulatory receptor expression or intracellular signalling thresholds can lead to diseases. For example, autoimmune diseases can result from altered regulation of B cell responses leading to the emergence of high-affinity autoreactive B cells, autoantibody production and tissue damage. The exact cause(s) of defective B cell responses in autoimmune diseases remains unknown. However, there is evidence that defects or mutations in genes that encode individual intracellular signalling proteins lead to autoimmune diseases, thus confirming that defects in intracellular pathways mediate autoimmune diseases. This review provides a synopsis of current knowledge of signalling proteins and pathways that regulate B lymphocyte responses and how defects in these could promote autoimmune diseases. Most of the evidence comes from studies of mouse models of disease and from genetically engineered mice. Some, however, also come from studying B lymphocytes from patients and from genome-wide association studies. Defining proteins and signalling pathways that underpin atypical B cell response in diseases will help in understanding disease mechanisms and provide new therapeutic avenues for precision therapy.
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Affiliation(s)
- Taher E Taher
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Jonas Bystrom
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Voon H Ong
- Centre for Rheumatology and Connective Tissue Diseases, Royal Free Hospital, University College London, London, UK
| | | | - Yves Renaudineau
- Immunology Laboratory, University of Brest Medical School, Brest, France
| | - David J Abraham
- Centre for Rheumatology and Connective Tissue Diseases, Royal Free Hospital, University College London, London, UK
| | - Rizgar A Mageed
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.
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5
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Choi YH, Han Y, Lee SH, Jin YH, Bahn M, Hur KC, Yeo CY, Lee KY. Cbl-b and c-Cbl negatively regulate osteoblast differentiation by enhancing ubiquitination and degradation of Osterix. Bone 2015; 75:201-9. [PMID: 25744063 DOI: 10.1016/j.bone.2015.02.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 11/28/2022]
Abstract
E3 ubiquitin ligase Cbl-b and c-Cbl play important roles in bone formation and maintenance. Cbl-b and c-Cbl regulate the activity of various receptor tyrosine kinases and intracellular protein tyrosine kinases mainly by regulating the degradation of target proteins. However, the precise mechanisms of how Cbl-b and c-Cbl regulate osteoblast differentiation are not well known. In this study, we investigated potential targets of Cbl-b and c-Cbl. We found that Cbl-b and c-Cbl inhibit BMP2-induced osteoblast differentiation in mesenchymal cells. Among various osteogenic transcription factors, we identified that Cbl-b and c-Cbl suppress the protein stability and transcriptional activity of Osterix. Our results suggest that Cbl-b and c-Cbl inhibit the function of Osterix by enhancing the ubiquitin-proteasome-mediated degradation of Osterix. Taken together, we propose novel regulatory roles of Cbl-b and c-Cbl during osteoblast differentiation in which Cbl-b and c-Cbl regulate the degradation of Osterix through the ubiquitin-proteasome pathway.
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Affiliation(s)
- You Hee Choi
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Younho Han
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Sung Ho Lee
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Yun-Hye Jin
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Minjin Bahn
- Department of Life Science and Global Top5 Research Program, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Kyu Chung Hur
- Department of Life Science and Global Top5 Research Program, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Chang-Yeol Yeo
- Department of Life Science and Global Top5 Research Program, Ewha Womans University, Seoul 120-750, Republic of Korea.
| | - Kwang Youl Lee
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea.
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Martinelli S, Stellacci E, Pannone L, D'Agostino D, Consoli F, Lissewski C, Silvano M, Cencelli G, Lepri F, Maitz S, Pauli S, Rauch A, Zampino G, Selicorni A, Melançon S, Digilio MC, Gelb BD, De Luca A, Dallapiccola B, Zenker M, Tartaglia M. Molecular Diversity and Associated Phenotypic Spectrum of Germline CBL Mutations. Hum Mutat 2015; 36:787-96. [PMID: 25952305 DOI: 10.1002/humu.22809] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 04/30/2015] [Indexed: 01/11/2023]
Abstract
Noonan syndrome (NS) is a relatively common developmental disorder with a pleomorphic phenotype. Mutations causing NS alter genes encoding proteins involved in the RAS-MAPK pathway. We and others identified Casitas B-lineage lymphoma proto-oncogene (CBL), which encodes an E3-ubiquitin ligase acting as a tumor suppressor in myeloid malignancies, as a disease gene underlying a condition clinically related to NS. Here, we further explored the spectrum of germline CBL mutations and their associated phenotype. CBL mutation scanning performed on 349 affected subjects with features overlapping NS and no mutation in NS genes allowed the identification of five different variants with pathological significance. Among them, two splice-site changes, one in-frame deletion, and one missense mutation affected the RING domain and/or the adjacent linker region, overlapping cancer-associated defects. A novel nonsense mutation generating a v-Cbl-like protein able to enhance signal flow through RAS was also identified. Genotype-phenotype correlation analysis performed on available records indicated that germline CBL mutations cause a variable phenotype characterized by a relatively high frequency of neurological features, predisposition to juvenile myelomonocytic leukemia, and low prevalence of cardiac defects, reduced growth, and cryptorchidism. Finally, we excluded a major contribution of two additional members of the CBL family, CBLB and CBLC, to NS and related disorders.
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Affiliation(s)
- Simone Martinelli
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
| | - Emilia Stellacci
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
| | - Luca Pannone
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy.,Dipartimento di Medicina Sperimentale, Sapienza Università di Roma, Rome, Italy
| | - Daniela D'Agostino
- Department of Medical Genetics, McGill University Health Centre, Montreal Children's Hospital, Montreal, Quebec, Canada
| | - Federica Consoli
- Dipartimento di Medicina Sperimentale, Sapienza Università di Roma, Rome, Italy.,Laboratorio Mendel, Istituto di Ricovero e Cura a Carattere Scientifico-Casa Sollievo della Sofferenza, Rome, Italy
| | - Christina Lissewski
- Institute of Human Genetics, University Hospital of Magdeburg, Otto-von-Guericke-University, Magdeburg, Germany
| | - Marianna Silvano
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
| | - Giulia Cencelli
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
| | | | - Silvia Maitz
- Dipartimento di Pediatria, Genetica Clinica, Ospedale S. Gerardo, Università di Milano-Bicocca, Monza, Italy
| | - Silke Pauli
- Institute of Human Genetics, University of Göttingen, Göttingen, Germany
| | - Anita Rauch
- Institute of Medical Genetics, University of Zurich, Schlieren-Zurich, Switzerland
| | - Giuseppe Zampino
- Istituto di Clinica Pediatrica, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Angelo Selicorni
- Dipartimento di Pediatria, Genetica Clinica, Ospedale S. Gerardo, Università di Milano-Bicocca, Monza, Italy
| | - Serge Melançon
- Department of Medical Genetics, McGill University Health Centre, Montreal Children's Hospital, Montreal, Quebec, Canada
| | | | - Bruce D Gelb
- Mindich Child Health and Development Institute and Departments of Pediatrics and Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York
| | - Alessandro De Luca
- Laboratorio Mendel, Istituto di Ricovero e Cura a Carattere Scientifico-Casa Sollievo della Sofferenza, Rome, Italy
| | | | - Martin Zenker
- Institute of Human Genetics, University Hospital of Magdeburg, Otto-von-Guericke-University, Magdeburg, Germany
| | - Marco Tartaglia
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
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7
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Noble M, Mayer-Pröschel M, Li Z, Dong T, Cui W, Pröschel C, Ambeskovic I, Dietrich J, Han R, Yang YM, Folts C, Stripay J, Chen HY, Stevens BM. Redox biology in normal cells and cancer: restoring function of the redox/Fyn/c-Cbl pathway in cancer cells offers new approaches to cancer treatment. Free Radic Biol Med 2015; 79:300-23. [PMID: 25481740 PMCID: PMC10173888 DOI: 10.1016/j.freeradbiomed.2014.10.860] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 10/29/2014] [Accepted: 10/30/2014] [Indexed: 12/12/2022]
Abstract
This review discusses a unique discovery path starting with novel findings on redox regulation of precursor cell and signaling pathway function and identification of a new mechanism by which relatively small changes in redox status can control entire signaling networks that regulate self-renewal, differentiation, and survival. The pathway central to this work, the redox/Fyn/c-Cbl (RFC) pathway, converts small increases in oxidative status to pan-activation of the c-Cbl ubiquitin ligase, which controls multiple receptors and other proteins of central importance in precursor cell and cancer cell function. Integration of work on the RFC pathway with attempts to understand how treatment with systemic chemotherapy causes neurological problems led to the discovery that glioblastomas (GBMs) and basal-like breast cancers (BLBCs) inhibit c-Cbl function through altered utilization of the cytoskeletal regulators Cool-1/βpix and Cdc42, respectively. Inhibition of these proteins to restore normal c-Cbl function suppresses cancer cell division, increases sensitivity to chemotherapy, disrupts tumor-initiating cell (TIC) activity in GBMs and BLBCs, controls multiple critical TIC regulators, and also allows targeting of non-TICs. Moreover, these manipulations do not increase chemosensitivity or suppress division of nontransformed cells. Restoration of normal c-Cbl function also allows more effective harnessing of estrogen receptor-α (ERα)-independent activities of tamoxifen to activate the RFC pathway and target ERα-negative cancer cells. Our work thus provides a discovery strategy that reveals mechanisms and therapeutic targets that cannot be deduced by standard genetics analyses, which fail to reveal the metabolic information, isoform shifts, protein activation, protein complexes, and protein degradation critical to our discoveries.
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Affiliation(s)
- Mark Noble
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Margot Mayer-Pröschel
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Zaibo Li
- Department of Pathology, Ohio State University Wexner Medical Center, 410W 10th Avenue, E403 Doan Hall, Columbus, OH 43210-1240, USA.
| | - Tiefei Dong
- University of Michigan Tech Transfer, 1600 Huron Pkwy, 2nd Floor, Building 520, Ann Arbor, MI 48109-2590, USA.
| | - Wanchang Cui
- Department of Radiation Oncology, University of Maryland School of Medicine,10 South Pine Street, MSTF Room 600, Baltimore, MD 21201, USA.
| | - Christoph Pröschel
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Ibro Ambeskovic
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Joerg Dietrich
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Yawkey 9E, Boston, MA 02114, USA.
| | - Ruolan Han
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Yin Miranda Yang
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Christopher Folts
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Jennifer Stripay
- Department of Biomedical Genetics and University of Rochester Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Hsing-Yu Chen
- Harvard Medical School, Department of Cell Biology 240 Longwood Avenue Building C1, Room 513B Boston, MA 02115, USA.
| | - Brett M Stevens
- University of Colorado School of Medicine, Division of Hematology, 12700 E. 19th Avenue, Campus Box F754-AMCA, Aurora, CO 80045, USA.
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Choi YH, Kim H, Han Y, Jin YH, Lee KY. Cbl regulates the activity of SIRT2. Biochem Biophys Res Commun 2014; 453:557-62. [DOI: 10.1016/j.bbrc.2014.09.125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 09/27/2014] [Indexed: 01/22/2023]
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9
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Liu Q, Zhou H, Langdon WY, Zhang J. E3 ubiquitin ligase Cbl-b in innate and adaptive immunity. Cell Cycle 2014; 13:1875-84. [PMID: 24875217 DOI: 10.4161/cc.29213] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Casitas B-lineage lymphoma proto-oncogene-b (Cbl-b), a RING finger E3 ubiquitin-protein ligase, has been demonstrated to play a crucial role in establishing the threshold for T-cell activation and controlling peripheral T-cell tolerance via multiple mechanisms. Accumulating evidence suggests that Cbl-b also regulates innate immune responses and plays an important role in host defense to pathogens. Understanding the signaling pathways regulated by Cbl-b in innate and adaptive immune cells is therefore essential for efficient manipulation of Cbl-b in emerging immunotherapies for human disorders such as autoimmune diseases, allergic inflammation, infections, and cancer. In this article, we review the latest developments in the molecular structural basis of Cbl-b function, the regulation of Cbl-b expression, the signaling mechanisms of Cbl-b in immune cells, as well as the biological function of Cbl-b in physiological and pathological immune responses in animal models and human diseases.
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Affiliation(s)
- Qingjun Liu
- Laboratory of Immunohematology; Beijing Institute of Transfusion Medicine; Beijing, PR China; Department of Microbial Infection and Immunity; The Ohio State University; Columbus, OH USA
| | - Hong Zhou
- Laboratory of Immunohematology; Beijing Institute of Transfusion Medicine; Beijing, PR China
| | - Wallace Y Langdon
- School of Pathology and Laboratory Medicine; University of Western Australia; Crawley, Western Australia, Australia
| | - Jian Zhang
- Department of Microbial Infection and Immunity; The Ohio State University; Columbus, OH USA
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10
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Nadeau S, An W, Palermo N, Feng D, Ahmad G, Dong L, Borgstahl GEO, Natarajan A, Naramura M, Band V, Band H. Oncogenic Signaling by Leukemia-Associated Mutant Cbl Proteins. ACTA ACUST UNITED AC 2013; Suppl 6. [PMID: 23997989 DOI: 10.4172/2161-1009.s6-001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Members of the Cbl protein family (Cbl, Cbl-b, and Cbl-c) are E3 ubiquitin ligases that have emerged as critical negative regulators of protein tyrosine kinase (PTK) signaling. This function reflects their ability to directly interact with activated PTKs and to target them as well as their associated signaling components for ubiquitination. Given the critical roles of PTK signaling in driving oncogenesis, recent studies in animal models and genetic analyses in human cancer have firmly established that Cbl proteins function as tumor suppressors. Missense mutations or small in-frame deletions within the regions of Cbl protein that are essential for its E3 activity have been identified in nearly 5% of leukemia patients with myelodysplastic/myeloproliferative disorders. Based on evidence from cell culture studies, in vivo models and clinical data, we discuss the potential signaling mechanisms of mutant Cbl-driven oncogenesis. Mechanistic insights into oncogenic Cbl mutants and associated animal models are likely to enhance our understanding of normal hematopoietic stem cell homeostasis and provide avenues for targeted therapy of mutant Cbl-driven cancers.
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Affiliation(s)
- Scott Nadeau
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 985950 Nebraska Medical Center Omaha, NE 68198-5950, USA ; Departments of Genetics, Cell Biology & Anatomy, University of Nebraska Medical Center, 985950 Nebraska Medical Center Omaha, NE 68198-5950, USA
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11
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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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12
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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 2012. [PMID: 23085373 DOI: 10.1016/j.bbamcr] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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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13
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Watson ARO, Janik DK, Lee WT. Superantigen-induced CD4 memory T cell anergy. I. Staphylococcal enterotoxin B induces Fyn-mediated negative signaling. Cell Immunol 2012; 276:16-25. [PMID: 22386537 DOI: 10.1016/j.cellimm.2012.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 12/15/2011] [Accepted: 02/07/2012] [Indexed: 12/15/2022]
Abstract
Memory CD4 T cells must provide robust protection for an organism while still maintaining self-tolerance. Superantigens reveal a memory cell-specific regulatory pathway, by which signaling through the TCR can lead to clonal tolerance (anergy). Here we show that the src kinase Fyn is a critical regulator of anergy in murine memory CD4 T cells induced by the bacterial superantigen staphylococcal enterotoxin B (SEB). Exposure to SEB results in impaired TCR signaling due to failed CD3/ZAP-70 complex formation. Further, signal transduction through the TCR remains similarly blocked when anergic memory cells are subsequently exposed to agonist peptide antigen. Pharmacological inhibition or genetic elimination of Fyn kinase reverses memory cell anergy, resulting in SEB-induced cell proliferation. The mechanism underlying impaired TCR signaling and subsequent memory cell anergy must involve a Fyn signaling pathway given that the suppression of Fyn activity restores CD3/ZAP-70 complex formation and TCR proximal signaling.
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Affiliation(s)
- Andrew R O Watson
- The Department of Biomedical Sciences, The School of Public Health, The University at Albany, Albany, NY 12201-0509, United States
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14
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Bertagnolo V, Brugnoli F, Grassilli S, Nika E, Capitani S. Vav1 in differentiation of tumoral promyelocytes. Cell Signal 2011; 24:612-20. [PMID: 22133616 DOI: 10.1016/j.cellsig.2011.11.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 11/08/2011] [Indexed: 02/06/2023]
Abstract
The multidomain protein Vav1, in addition to promote the acquisition of maturation related properties by normal hematopoietic cells, is a key player in the ATRA- and PMA-induced completion of the differentiation program of tumoral myeloid precursors derived from APL. This review is focussed on the role of Vav1 in differentiating promyelocytes, as part of interconnected networks of functionally related proteins ended to regulate different aspects of myeloid maturation. The role of Vav1 in determining actin cytoskeleton reorganization alternative to the best known function as a GEF for small G proteins is discussed, as well as the binding of Vav1 with cytoplasmic and nuclear signaling molecules which provides a new perspective in the modulation of nuclear architecture and activity. In particular, new hints are provided on the ability of Vav1 to determine the nuclear amount of proteins implicated in modulating mRNA production and stability and in regulating the ATRA-dependent protein expression also by direct interaction with transcription factors known to drive the ATRA-induced maturation of myeloid cells. The reviewed findings summarize the major advances in the understanding of additional, non conventional functions connected with the vast interactive potential of Vav1.
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Affiliation(s)
- Valeria Bertagnolo
- Section of Human Anatomy, Department of Morphology and Embryology, University of Ferrara, Ferrara, Italy.
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15
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Kondo Y, Tokuda N, Furukawa K, Ando R, Uchikawa M, Zhang Q, Xiaoyan F, Furukawa K. Efficient generation of useful monoclonal antibodies reactive with globotriaosylceramide using knockout mice lacking Gb3/CD77 synthase. Glycoconj J 2011; 28:371-84. [PMID: 21660412 DOI: 10.1007/s10719-011-9335-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 05/03/2011] [Accepted: 05/15/2011] [Indexed: 12/01/2022]
Abstract
Efficient generation of useful monoclonal antibodies (mAbs) with high performance in cancer therapeutics has been expected. Generation of mAbs reactive with globotriaosylceramide (Gb3/CD77) was compared between A/J mice and Gb3/CD77 synthase-deficient (A4GalT-knockout) mice by immunizing Gb3-liposome. Specificity and functions of established antibodies were examined by ELISA, TLC- immunostaining, cytotoxicity of cancer cells and immunoblotting. Compared with results with conventional mice, better generation of mAbs with higher functions has been achieved with A4GalT-knockout mice, i.e. acquisition of IgG class antibodies, activities in antibody-dependent cell-mediated cytotoxicity, complement-dependent cytotoxicity, and aggregation activity toward a Burkitt's lymphoma line Ramos. Binding of mAb k52 induced tyrosine phosphorylation of several proteins in Ramos cells. One of the strongest phosphorylation bands turned out to be c-Cbl. Pretreatment of B cell lines with mAbs resulted in the attenuation of BCR-mimicking signaling. All these results suggested that A4GalT-knockout mice are very useful to generate mAbs against globo-series glycolipids, and that suppressive signaling pathway driven by endogenous Gb3-ligand molecules might be present in B cells.
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Affiliation(s)
- Yuji Kondo
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Tsurumai, Showa-ku, Nagoya, Japan
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16
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Naramura M, Nadeau S, Mohapatra B, Ahmad G, Mukhopadhyay C, Sattler M, Raja SM, Natarajan A, Band V, Band H. Mutant Cbl proteins as oncogenic drivers in myeloproliferative disorders. Oncotarget 2011; 2:245-50. [PMID: 21422499 PMCID: PMC3134300 DOI: 10.18632/oncotarget.233] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 03/20/2011] [Indexed: 12/02/2022] Open
Abstract
Casitas B-lineage lymphoma (Cbl) family proteins are evolutionarily-conserved attenuators of protein tyrosine kinase (PTK) signaling. Biochemical analyses over the past two decades have firmly established that the negative regulatory functions of Cbl proteins are mediated through their ability to facilitate ubiquitination and thus promote degradation of PTKs. As aberrant activation of PTKs is frequently associated with oncogenesis, it has long been postulated that loss of normal Cbl functions may lead to unregulated activation of PTKs and cellular transformation. In the last few years, mutations in the CBL gene have been identified in a subset of human patients with myeloid malignancies. Here we discuss insights gained from the analyses of Cbl mutants both in human patients and in animal models and propose potential mechanisms of oncogenesis through this pathway.
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Affiliation(s)
- Mayumi Naramura
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Scott Nadeau
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Bhopal Mohapatra
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Biochemistry & Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Gulzar Ahmad
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
| | - Chandrani Mukhopadhyay
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
| | - Martin Sattler
- Dana Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Srikumar M Raja
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE
| | - Vimla Band
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Hamid Band
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, NE
- Department of Biochemistry & Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, NE
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17
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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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18
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Itch-/- alphabeta and gammadelta T cells independently contribute to autoimmunity in Itchy mice. Blood 2008; 111:4273-7282. [PMID: 18256323 DOI: 10.1182/blood-2007-10-115667] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
E3 ubiquitin ligases determine which intracellular proteins are targets of the ubiquitin conjugation pathway and thus play a key role in determining the half-life, subcellular localization and/or activation status of their target proteins. Itchy mice lack the E3 ligase, Itch, and show dysregulation of T lymphocytes and the induction of a lethal autoimmune inflammatory condition. Itch is widely expressed in hematopoietic and nonhematopoietic cells, and we demonstrate that disease is transferred exclusively by hematopoietic cells. Moreover, distinct manifestations of the autoimmune inflammatory phenotype are contributed by discrete populations of lymphocytes. The presence of Itch-deficient alphabeta T cells drives expansion of peritoneal B1b cells and elevated IgM levels, which correlate with itching and pathology. In contrast, Itch(-/-) interleukin-4-producing gammadelta T cells, even in the absence of alphabeta T cells, are associated with elevated levels of IgE and an inflammatory condition. These data indicate that disruption of an E3 ubiquitin ligase in alphabeta T cells can subvert a B-cell subpopulation, which normally functions to control particular microbial pathogens in a T-independent manner, to contribute to autoimmunity. In addition, disruption of Itch in innate gammadelta T cells can influence autoimmune pathology and might therefore require distinct therapeutic intervention.
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19
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Chiang JY, Jang IK, Hodes R, Gu H. Ablation of Cbl-b provides protection against transplanted and spontaneous tumors. J Clin Invest 2007; 117:1029-36. [PMID: 17364027 PMCID: PMC1810570 DOI: 10.1172/jci29472] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 02/06/2007] [Indexed: 02/03/2023] Open
Abstract
A significant challenge to efforts aimed at inducing effective antitumor immune responses is that CD8(+) T cells, which play a prominent role in these responses, may be unable to respond to tumors that lack costimulatory signals and that are protected by an immune suppressive environment such as that mediated by TGF-beta produced by tumor cells themselves or by infiltrating Tregs, often resulting in tolerance or anergy of tumor-specific T cells. Here we show that the in vitro activation of Cblb(-/-) CD8(+) T cells does not depend on CD28 costimulation and is resistant to TGF-beta suppression. In vivo studies further demonstrated that Cblb(-/-) mice, but not WT controls, efficiently rejected inoculated E.G7 and EL4 lymphomas that did not express B7 ligands and that introduction of the Cblb(-/-) mutation into tumor-prone ataxia telangiectasia mutated-deficient mice markedly reduced the incidence of spontaneous thymic lymphomas. Immunohistological study showed that E.G7 tumors from Cblb(-/-) mice contained massively infiltrating CD8(+) T cells. Adoptive transfer of purified Cblb(-/-) CD8(+) T cells into E.G7 tumor-bearing mice led to efficient eradication of established tumors. Thus, our data indicate that ablation of Cbl-b can be an efficient strategy for eliciting immune responses against both inoculated and spontaneous tumors.
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Affiliation(s)
- Jeffrey Y. Chiang
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA.
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
National Institute on Aging, NIH, Bethesda, Maryland, USA
| | - Ihn Kyung Jang
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA.
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
National Institute on Aging, NIH, Bethesda, Maryland, USA
| | - Richard Hodes
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA.
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
National Institute on Aging, NIH, Bethesda, Maryland, USA
| | - Hua Gu
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA.
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
National Institute on Aging, NIH, Bethesda, Maryland, USA
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20
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Song H, Zhang J, Chiang YJ, Siraganian RP, Hodes RJ. Redundancy in B Cell Developmental Pathways: c-Cbl Inactivation Rescues Early B Cell Development through a B Cell Linker Protein-Independent Pathway. THE JOURNAL OF IMMUNOLOGY 2007; 178:926-35. [PMID: 17202354 DOI: 10.4049/jimmunol.178.2.926] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Deficiency in the adaptor protein B cell linker protein (BLNK) results in a substantial but incomplete block in B cell development, suggesting that alternative pathways exist for B lineage differentiation. Another adaptor protein, c-Cbl, plays a negative regulatory role in several BCR-signaling pathways. We therefore investigated the role of c-Cbl during B cell development and addressed the possibility that redundancies in pathways for B cell differentiation could be further revealed by eliminating negative effects mediated by c-Cbl. Strikingly, c-Cbl inactivation reversed a number of the critical defects in early B cell differentiation that are seen in BLNK-deficient mice. c-Cbl(-/-)BLNK(-/-) mice exhibited normalized down-regulation of pre-BCR and CD43, up-regulation of MHC class II, and augmented L chain rearrangement, resulting in a successful transition from pre-B cells to immature B cells. c-Cbl inactivation also reversed the potentially tumor-predisposing hyperproliferative response of BLNK(-/-) pre-B cells to IL-7. Pre-BCR cross-linking induced enhanced and prolonged tyrosine phosphorylation in c-Cbl(-/-)BLNK(-/-) pre-BCR(+) pre-B cells compared with c-Cbl(+/-)BLNK(-/-) cells, including elevated phosphorylation of Lyn, Syk, Btk, and phospholipase C-gamma2. Our studies suggest that some, but not all, pre-BCR-triggered developmental events can be mediated by BLNK-independent pathways that are negatively regulated by c-Cbl, and further suggest that different events during early B cell development require different strength or duration of pre-BCR signaling.
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Affiliation(s)
- Haifeng Song
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
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21
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Yao B, Zhang J, Dai H, Sun J, Jiao Y, Tang Y, Wu J, Shi Y. Solution structure of the second SH3 domain of human CMS and a newly identified binding site at the C-terminus of c-Cbl. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:35-43. [PMID: 17188587 DOI: 10.1016/j.bbapap.2006.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2006] [Revised: 09/12/2006] [Accepted: 09/12/2006] [Indexed: 10/24/2022]
Abstract
CMS, cas ligand with multiple Src homology 3 (SH3) domains, belongs to a family of ubiquitously expressed adaptor proteins. Among the CMS binding proteins, c-Cbl has been mostly extensively studied. It was reported that the motif PKPFPR (residues 824-829) of c-Cbl can bind to the N-terminus SH3 domains of CMS. Here we report the solution structure of the second SH3 domain of CMS (CMS_SH3_B), furthermore, we have identified that a peptide from residues 701 to 714 of c-Cbl (Cbl-p), i.e. MTPSSRPLRPLDTS, can specially bind to CMS_SH3_B using NMR chemical shift perturbation, suggesting that the peptide is a new potential CMS binding site. Among the peptide, TPSSRPLR is the core binding motif and Arg709 plays a key role in the interaction. Cbl-p binding interface on CMS_SH3_B along a hydrophobic channel is composed of RT loop, n-Src loop and beta4 strand and divided into three pockets. This work indicates the solution structure of CMS_SH3_B bears the canonical beta-beta-beta-beta-alpha-beta fold and a new binding site in c-Cbl involved in its interaction with CMS, which probably contributes to the clustering of CMS. All the information provided here should be beneficial for the future functional study of CMS.
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Affiliation(s)
- Bo Yao
- School of Life Science, Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230027, Peoples Republic of China
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22
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Lottin-Divoux S, Jean D, Le Romancer M, Frade R. Activation of Epstein-Barr virus/C3d receptor (gp140, CR2, CD21) on human B lymphoma cell surface triggers Cbl tyrosine phosphorylation, its association with p85 subunit, Crk-L and Syk and its dissociation with Vav. Cell Signal 2005; 18:1219-25. [PMID: 16289966 DOI: 10.1016/j.cellsig.2005.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 09/30/2005] [Accepted: 10/03/2005] [Indexed: 10/25/2022]
Abstract
It is well established that CD21 activation on human B cell surface triggers B cell proliferation. We previously demonstrated that CD21 activation also triggers tyrosine phosphorylation of two components, p95 and p120, both interacting with SH2 domains of the p85 subunit of PI 3-kinase. We successively identified p95 as the nucleolin and the first signal transduction pathway specifically triggered by CD21 activation, i.e.: pp60Src activation, tyrosine phosphorylation of p95 nucleolin, its interaction with SH2 domains of p85 subunit and PI 3-kinase activation, followed by AKT-GSK-3 activations. We herein identified the p120 component as the protooncoprotein Cbl and the first steps associated to its activation. First, CD21 activation triggered Cbl tyrosine phosphorylation, which required c-Src kinase but not PI 3-kinase or Syk kinase activities. Involvement of Src kinase in this step was supported by inhibition of Cbl phosphorylation and its interactions with other components when cells were either preincubated with specific Src inhibitor or transfected with dominant-negative c-Src form. Second, once tyrosine phosphorylated, Cbl interacts with SH2 domains of p85 subunit, SH2 domains of Crk-L and with tyrosine phosphorylated Syk kinase. The third and unexpected feature was to found that, at the contrary of BCR or of CD19 (herein also analyzed for the first time), CD21 activation triggers dissociation of Cbl-Vav complex. Thus, these results provide the first molecular basis of a new signal transduction pathway specifically triggered by CD21 activation.
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Affiliation(s)
- Séverine Lottin-Divoux
- INSERM U.672 (ex U.354), Immunochimie des Régulations Cellulaires et des Interactions Virales, Bâtiment G8, Campus 1, 5 rue Henri Desbruères, Génopole d'Evry, 91030, EVRY Cedex, France
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23
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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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24
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Qu X, Miah SMS, Hatani T, Okazaki M, Hori-Tamura N, Yamamura H, Hotta H, Sada K. Selective Inhibition of FcεRI-Mediated Mast Cell Activation by a Truncated Variant of Cbl-b Related to the Rat Model of Type 1 Diabetes Mellitus. ACTA ACUST UNITED AC 2005; 137:711-20. [PMID: 16002993 DOI: 10.1093/jb/mvi088] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Ubiquitin-protein ligase Cbl-b negatively regulates high affinity IgE receptor (FcepsilonRI)-mediated degranulation and cytokine gene transcription in mast cells. In this study, we have examined the role of a truncated variant of Cbl-b related to the rat model of type 1 diabetes mellitus using the mast cell signaling model. Overexpression of the truncated Cbl-b that lacks the C-terminal region did not suppress the activation of proximal and distal signaling molecules leading to degranulation. FcepsilonRI-mediated tyrosine phosphorylation of Syk, Gab2, and phospholipase C-gamma1, and activation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAP kinase), and inhibitor of nuclear factor kappaB kinase (IKK), and generation of Rac1 are unaffected in cells overexpressing the truncated Cbl-b in the lipid raft. On the other hand, FcepsilonRI-mediated transcriptional activation of nuclear factor of activated T cells (NFAT), and transcription of interleukin-3 (IL-3) and IL-4 mRNA are inhibited by overexpression of the truncated variant of Cbl-b. This suppression parallels the re-compartmentalization of specific effector molecules in the lipid raft. These structural and functional analyses reveal the mechanism underlying the selective inhibition of cellular signaling by the truncated variant of Cbl-b related to insulin-dependent diabetes mellitus.
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Affiliation(s)
- Xiujuan Qu
- Division of Proteomics and Division of Microbiology, Department of Genome Sciences, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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25
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Scott RP, Eketjäll S, Aineskog H, Ibáñez CF. Distinct Turnover of Alternatively Spliced Isoforms of the RET Kinase Receptor Mediated by Differential Recruitment of the Cbl Ubiquitin Ligase. J Biol Chem 2005; 280:13442-9. [PMID: 15677445 DOI: 10.1074/jbc.m500507200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alternative splicing of transcripts encoding the RET kinase receptor leads to isoforms differing in their cytoplasmic tail. Although in vitro studies have demonstrated a higher transforming activity of the long RET isoform (RET51), only the short isoform (RET9) can rescue the effects of a RET null mutation in the enteric nervous system and kidney development. The molecular basis underlying the distinct functions of the two RET isoforms is not understood. Here we demonstrated that activated RET51 associated more strongly with the ubiquitin ligase Cbl than did RET9, leading to increased ubiquitylation and faster turnover of RET51. The association of Cbl with RET was indirect and was mediated through Grb2. A constitutive complex of Grb2 and Cbl could be recruited to both receptor isoforms via docking of Shc to phosphorylated Tyr-1062 in RET. A mutant Shc protein unable to recruit the Grb2.Cbl complex decreased the turnover and prolonged the half-life of RET9, thus ascribing a previously unknown negative role to the Shc adaptor molecule. In addition, phosphorylation of Tyr-1096, which is present in RET51 but absent in RET9, endowed the longer isoform with a second route to recruit the Grb2.Cbl complex. These findings establish a mechanism for the differential down-regulation of RET9 and RET51 signaling that could explain the apparently paradoxical activities of these two RET isoforms. More generally, these results illustrate how alternative splicing can regulate the half-life and function of a growth factor receptor.
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Affiliation(s)
- Rizaldy P Scott
- Division of Molecular Neurobiology, Department of Neuroscience, Karolinska Institute, S-17177 Stockholm, Sweden
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26
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Datta SK, Zhang L, Xu L. T-helper cell intrinsic defects in lupus that break peripheral tolerance to nuclear autoantigens. J Mol Med (Berl) 2005; 83:267-78. [PMID: 15630591 DOI: 10.1007/s00109-004-0624-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Accepted: 11/16/2004] [Indexed: 12/22/2022]
Abstract
Special populations of T helper cells drive B cells to produce IgG class switched, pathogenic autoantibodies in lupus. The major source of antigenic determinants (epitopes) that trigger interactions between lupus T and B cells is nucleosomes of apoptotic cells. These epitopes can be used for antigen-specific therapy of lupus. Secondly, the autoimmune T cells of lupus are sustained because they resist anergy and activation-induced programmed cell death by markedly upregulating cyclooxygenase (COX) 2 along with the antiapoptotic molecule c-FLIP. Only certain COX-2 inhibitors block pathogenic anti-DNA autoantibody production in lupus by causing death of autoimmune T helper cells. Hence COX-2 inhibitors may work independently of their ability to block the enzymatic function of COX-2, and structural peculiarities of these select inhibitors may lead to better drug discovery and design.
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Affiliation(s)
- Syamal K Datta
- Department of Medicine, Feinberg School of Medicine, Northwestern University, 240 East Huron St., Chicago, IL 60611, USA.
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27
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Gelkop S, Babichev Y, Kalifa R, Tamir A, Isakov N. Involvement of crk adapter proteins in regulation of lymphoid cell functions. Immunol Res 2004; 28:79-91. [PMID: 14610286 DOI: 10.1385/ir:28:2:79] [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: 11/11/2022]
Abstract
The Crk adapter proteins consist of Src homology 2 (SH2) SH2 and SH3 domains, which bind tyrosine-phosphorylated peptides and polyproline-rich motives, respectively. They are linked to multiple signaling pathways in different cell types, including lymphocytes, and because of their lack of catalytic activity, many studies on Crk were aimed at the identification of their binding partners and determination of the physiologic meaning of these interactions. Crk proteins were found to be involved in the early steps of lymphocyte activation through their SH2-mediated transient interaction with signal-transducing molecules, such as Cbl, ZAP-70, CasL, and STAT5. In addition, Crk proteins are constitutively associated with effector molecules that mediate cell adhesion and thereby regulate lymphocyte extravasation and recruitment to sites of inflammation. This article describes selected studies of Crk, performed predominantly in lymphocytes, and discusses their potential relevance to the role of Crk in the regulation of lymphocyte functions.
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Affiliation(s)
- Sigal Gelkop
- Department of Microbiology and Immunology, Faculty of Health Sciences, and the Cancer Research Center, Ben Gurion University of the Negev, Beer Sheva, Israel
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28
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Abstract
Ubiquitin (Ub)-protein conjugation represents a novel means of posttranscriptional modification in a proteolysis-dependent or -independent manner. E3 Ub ligases play a key role in governing the cascade of Ub transfer reactions by recognizing and catalyzing Ub conjugation to specific protein substrates. The E3s, which can be generally classified into HECT-type and RING-type families, are involved in the regulation of many aspects of the immune system, including the development, activation, and differentiation of lymphocytes, T cell-tolerance induction, antigen presentation, immune evasion, and virus budding. E3-promoted ubiquitination affects a wide array of biological processes, such as receptor downmodulation, signal transduction, protein processing or translocation, protein-protein interaction, and gene transcription, in addition to proteasome-mediated degradation. Deficiency or mutation of some of the E3s like Cbl, Cbl-b, or Itch, causes abnormal immune responses such as autoimmunity, malignancy, and inflammation. This review discusses our current understanding of E3 Ub ligases in both innate and adaptive immunity. Such knowledge may facilitate the development of novel therapeutic approaches for immunological diseases.
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Affiliation(s)
- Yun-Cai Liu
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA.
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29
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Feng JM, Fernandes AO, Campagnoni CW, Hu YH, Campagnoni AT. The golli-myelin basic protein negatively regulates signal transduction in T lymphocytes. J Neuroimmunol 2004; 152:57-66. [PMID: 15223237 DOI: 10.1016/j.jneuroim.2004.03.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Accepted: 03/29/2004] [Indexed: 11/27/2022]
Abstract
Protein kinase C (PKC) plays a critical role in signal transduction controlling T lymphocyte activation. Both positive and negative regulation of signal transduction is needed for proper control of T lymphocyte activation. We have found that a golli product of the myelin basic protein (MBP) gene can serve as a negative regulator of signaling pathways in the T lymphocyte, particularly the PKC pathway. Increased expression of golli BG21 in Jurkat T cells strongly inhibits anti-CD3-induced IL-2-luciferase activity, an indicator of T lymphocyte activation. Golli BG21 can be phosphorylated by PKC in vitro and its phosphorylation increases in PMA-activated Jurkat cells. BG21 inhibits the PMA-induced increase in AP-1 or NF-kappaB activation, consistent with golli acting in a PKC-mediated cellular event. Golli BG21 inhibition of the PKC pathway is not due to a direct action on PKC activation but in the cascade following PKC activation, since BG21 neither reduces PKC enzyme activity nor blocks the membrane association of PKCtheta brought on by T lymphocyte activation. The inhibitory function of BG21 is independent of its phosphorylation by PKC because a mutant BG21, in which the PKC sites have been mutated, is as effective as the wild type BG21 in inhibiting the PMA-induced AP-1 activation. Structure-function assays indicate that BG21 inhibitory activity resides in the golli domain rather than in MBP domain of the molecule. These results reveal a novel role for MBP gene products in T lymphocytes within the immune system.
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Affiliation(s)
- Ji-Ming Feng
- UCLA Medical School, Neuropsychiatric Institute, Room 47-448, 760 Westwood Plaza, Los Angeles, CA 90024-17519, USA.
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30
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Abstract
Regulation of tyrosine kinase-mediated cellular activation through antigen receptors is of great biological and practical significance. The evolutionarily conserved Cbl family ubiquitin ligases have emerged as key negative regulators of activated tyrosine kinase-coupled receptors, and their impaired function switches a normal immune response into autoimmunity. Cbl proteins facilitate the ubiquitinylation of activated tyrosine kinases and other signaling proteins and of the signaling chains of receptors themselves; monoubiquitin tag promotes sorting of activated receptors and associated proteins into internal vesicles of the multivesicular body, facilitating their lysosomal degradation, whereas polyubiquitin tag promotes proteasomal degradation. Notably, increased expression of Cbl proteins and other ubiquitin ligases is a component of anergic signaling program in T cells. Thus, controlled destruction of the signaling apparatus has emerged as a key to fine-tuning antigen receptor signaling. Further studies of this pathway are likely to elucidate the pathogenesis of autoimmune diseases and offer new therapeutic targets.
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Affiliation(s)
- Lei Duan
- Division of Molecular Oncology, Department of Medicine, Evanston Northwestern Healthcare Research Institute, Feinberg School of Medicine, Northwestern University, IL 60201, USA
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31
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Ghosh AK, Reddi AL, Rao NL, Duan L, Band V, Band H. Biochemical basis for the requirement of kinase activity for Cbl-dependent ubiquitinylation and degradation of a target tyrosine kinase. J Biol Chem 2004; 279:36132-41. [PMID: 15208330 DOI: 10.1074/jbc.m404189200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the Cbl family of ubiquitin ligases have emerged as crucial negative regulators of tyrosine kinase signaling. These proteins preferentially interact with and target activated tyrosine kinases for ubiquitinylation, thereby facilitating the lysosomal sorting of receptor tyrosine kinases or proteasomal degradation of nonreceptor tyrosine kinases. Recent work has indicated a crucial role of the target kinase activity in Cbl-dependent ubiquitinylation and degradation, but the biochemical basis for this requirement is not understood. Here, we have used the Src-family kinase Fyn, a well characterized Cbl target, to address this issue. Using defined Fyn mutants, we demonstrate that the kinase activity of Fyn is crucial for its Cbl-dependent ubiquitinylation and degradation, but a low level of ubiquitinylation and degradation of kinase-inactive Fyn mutants was consistently observed. Mutational induction of an open conformation enhanced the susceptibility of kinase-active Fyn to Cbl but was insufficient to promote the ubiquitinylation and degradation of kinase-inactive Fyn. Notably, the Cbl-dependent degradation of Fyn did not require the Fyn-mediated phosphorylation of Cbl. Finally, we show that the major determinant of the susceptibility of Fyn protein to Cbl-dependent ubiquitinylation and degradation is the extent to which it physically associates with Cbl; kinase activity of Fyn serves as a critical determinant to promote its association with Cbl, which we demonstrate is mediated by multiple protein-protein interactions. Our results strongly suggest that promotion of association with Cbl is the primary mechanism by which the kinase activity of the targets of Cbl contributes to their susceptibility to Cbl.
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Affiliation(s)
- Amiya K Ghosh
- Division of Molecular Oncology, Department of Medicine Evanston Northwestern Healthcare Research Institute, Feinberg School of Medicine and Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60201, USA
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32
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Hicke L, Dunn R. Regulation of membrane protein transport by ubiquitin and ubiquitin-binding proteins. Annu Rev Cell Dev Biol 2004; 19:141-72. [PMID: 14570567 DOI: 10.1146/annurev.cellbio.19.110701.154617] [Citation(s) in RCA: 875] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ubiquitin regulates protein transport between membrane compartments by serving as a sorting signal on protein cargo and by controlling the activity of trafficking machinery. Monoubiquitin attached to integral plasma membrane proteins or to associated transport modifiers serves as a regulated signal for internalization into the endocytic pathway. Similarly, monoubiquitin attached to biosynthetic and endocytic membrane proteins is a signal for sorting of cargo into vesicles that bud into the late endosome lumen for delivery into the lysosome. Ubiquitination of trans-acting endocytic proteins is also required for transport, and key endocytic proteins are modified by monoubiquitin. Regulatory enzymes of the ubiquitination machinery, ubiquitin ligases, control the timing and specificity of plasma membrane protein downregulation in such diverse biological processes as cell fate specification and neurotransmission. Monoubiquitin signals appended by these ligases are recognized by endocytic proteins carrying ubiquitin-binding motifs, including UBA, UEV, UIM, and CUE domains. The UIM proteins epsins and Hrs are excellent candidates for adaptors that link ubiquitinated cargo to the clathrin-based sorting machinery at appropriate regions of the endosomal or plasma membranes. Other ubiquitin-binding proteins also play crucial roles in cargo transport, although in most cases the role of ubiquitin-binding is not defined. Ubiquitin-binding proteins such as epsins, Hrs, and Vps9 are monoubiquitinated, indicating the general nature of ubiquitin regulation in endocytosis and suggesting new models to explain how recognition of monoubiquitin signals may be regulated.
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Affiliation(s)
- Linda Hicke
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA.
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33
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Fernandis AZ, Prasad A, Band H, Klösel R, Ganju RK. Regulation of CXCR4-mediated chemotaxis and chemoinvasion of breast cancer cells. Oncogene 2004; 23:157-67. [PMID: 14712221 DOI: 10.1038/sj.onc.1206910] [Citation(s) in RCA: 219] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The chemokine-CXCL12 and its receptor, CXCR4, have recently been shown to play an important role in regulating the directional migration of breast cancer cells to sites of metastasis. In the present study, we showed that CXCL12 enhanced the chemotaxis, chemoinvasion and adhesive properties of breast cancer cells; parameters that are critical for development of metastasis. We have also evaluated the signaling mechanisms that regulate CXCL12-induced and CXCR4-mediated breast cancer cell motility and invasion. These studies revealed that CXCL12 induces the tyrosine phosphorylation of focal adhesion kinase (FAK) at residues 397 and 577, and of RAFTK/Pyk2 at residues 402 and 579/580. The cytoskeletal proteins paxillin and Crk, as well as tyrosine phosphatase SHP2 and adaptor protein Cbl, were also phosphorylated. CXCL12 induced the activation of PI 3-kinase, and increased its association with Cbl and SHP2. PI 3-kinase, RAFTK/Pyk2 and tyrosine phosphatase inhibitors significantly blocked CXCL12-induced chemotaxis and chemoinvasion. The role of SHP2 and Cbl in CXCL12-induced chemotaxis and chemoinvasion in breast cancer cells was further defined by transiently overexpressing wild-type SHP2, wild-type Cbl, dominant-negative SHP2, Cbl mutants 70Z/3 and G306E or double transfectants of the Cbl and SHP2 constructs. We found a novel role of Cbl in CXCL12-induced chemotaxis, which may be mediated through the activation and formation of a multimeric complex comprised of Cbl, SHP2 and PI 3-kinase. We also observed the activation of matrix metalloproteinases 2 and 9 upon CXCL12 stimulation. These studies provide new information regarding signaling pathways that may regulate CXCL12-induced metastasis in breast cancer cells.
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Affiliation(s)
- Aaron Zefrin Fernandis
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
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Kumar K, Brady M, Shapiro R. Selective abolition of pancreatic RNase binding to its inhibitor protein. Proc Natl Acad Sci U S A 2003; 101:53-8. [PMID: 14681553 PMCID: PMC314137 DOI: 10.1073/pnas.0307268101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have modified RNase inhibitor (RI) protein so that it no longer detectably binds pancreatic RNases but retains near-native affinity for human angiogenin (ANG). The K(i) value for RNase A is increased by a factor of >10(8), from 36 fM to >4 microM, and the selectivity factor for ANG is now >10(9). This dramatic change was achieved by remodeling the human RI loop segment Cys-408 -Leu-409 -Gly-410, which makes minor interactions with pancreatic RNase but does not contact ANG. The modifications selected were designed to sterically hinder docking of the undesired ligand. Three of the variants tested (C408W, G410W, and C408W/G410W) bind RNase A with almost the same avidity as WT RI. However, combination of the 408/410 double Trp replacement with deletion of the intervening residue, Leu-409, was sufficient to abolish inhibition of RNase A and human pancreatic RNase. The K(i) value for ANG with the deletion variant is 1.1 fM, only 2-fold higher than with WT RI. This variant may have potential utility both as an anticancer drug targeting ANG and as a tool for the investigation of the biological function of ANG. More generally, these findings demonstrate that a protein-protein interaction can be effectively and specifically disrupted by redesigning an interface region that makes no major energetic contribution to complex stability. This finding, in turn, may have implications for the development of small molecules that modulate protein-protein interactions.
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Affiliation(s)
- Kapil Kumar
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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35
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Muñoz P, Navarro MDC, Pavón EJ, Salmerón J, Malavasi F, Sancho J, Zubiaur M. CD38 Signaling in T Cells Is Initiated within a Subset of Membrane Rafts Containing Lck and the CD3-ζ Subunit of the T Cell Antigen Receptor. J Biol Chem 2003; 278:50791-802. [PMID: 14523017 DOI: 10.1074/jbc.m308034200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study we present data supporting that most CD38 is pre-assembled in a subset of Brij 98-resistant raft vesicles, which were stable at 37 degrees C, and have relatively high levels of Lck and the CD3-zeta subunit of T cell antigen receptor-CD3 complex in contrast with a Brij 98-soluble pool, where CD38 is associated with CD3-zeta, and Lck is not detected. Our data further indicate that following CD38 engagement, LAT and Lck are tyrosine phosphorylated exclusively in Brij 98-resistant rafts, and some key signaling components translocate into rafts (i.e. Sos and p85-phosphatidylinositol 3-kinase). Moreover, N-Ras results activated within rafts immediately upon CD38 ligation, whereas activated Erk was mainly found in soluble fractions with delayed kinetics respective to Ras activation. Furthermore, full phosphorylation of CD3-zeta and CD3-epsilon only occurs in rafts, whereas partial CD3-zeta tyrosine phosphorylation occurs exclusively in the soluble pool, which correlated with increased levels of c-Cbl tyrosine phosphorylation in the non-raft fractions. Taken together, these results suggest that, unlike the non-raft pool, CD38 in rafts is able to initiate and propagate several activating signaling pathways, possibly by facilitating critical associations within other raft subsets, for example, LAT rafts via its capacity to interact with Lck and CD3-zeta. Overall, these findings provide the first evidence that CD38 operates in two functionally distinct microdomains of the plasma membrane.
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Affiliation(s)
- Pilar Muñoz
- Instituto de Parasitología y Biomedicina, Consejo Superior de Investigaciones Científicas, 18001 Granada, Spain
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36
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Auger JM, Best D, Snell DC, Wilde JI, Watson SP. c-Cbl negatively regulates platelet activation by glycoprotein VI. J Thromb Haemost 2003; 1:2419-26. [PMID: 14629478 DOI: 10.1046/j.1538-7836.2003.00464.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND The adapter protein c-Cbl has emerged as having a potential role in negative regulation of immune receptor signaling. The major platelet-signaling receptor for collagen, glycoprotein VI (GpVI), is associated with the Fc receptor (FcR) gamma-chain, and signals through a similar pathway to immune receptors. c-Cbl is tyrosine-phosphorylated in response to stimulation of GpVI, whereas phosphorylation of c-Cbl in thrombin-activated platelets is dependent on fibrinogen binding to the integrin GpIIb/IIIa. OBJECTIVE To investigate the role of c-Cbl in platelet signaling. METHODS Murine platelets lacking functional c-Cbl or Src family kinases were analyzed. RESULTS Phosphorylation of c-Cbl through GpVI is reduced in murine platelets deficient in the Src-family kinases Fyn and Lyn, demonstrating that they lie upstream of c-Cbl phosphorylation. Phosphorylation of several proteins of the GpVI-signaling pathway, including the FcR gamma-chain, Syk and phospholipase Cgamma2 (PLCgamma2), is increased in the absence of c-Cbl. In line with this, aggregation is potentiated in response to the GpVI-specific collagen-related peptide (CRP) after a slight delay. A delay in potentiation is also seen in response to stimulation by thrombin. CONCLUSIONS These observations demonstrate that c-Cbl negatively regulates platelet responses to GpVI agonists and to thrombin, with the latter effect possibly being mediated downstream of GpIIb/IIIa. c-Cbl may play a physiological role in helping to prevent unwanted platelet activation in vivo.
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Affiliation(s)
- J M Auger
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK.
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37
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Miura-Shimura Y, Duan L, Rao NL, Reddi AL, Shimura H, Rottapel R, Druker BJ, Tsygankov A, Band V, Band H. Cbl-mediated ubiquitinylation and negative regulation of Vav. J Biol Chem 2003; 278:38495-504. [PMID: 12881521 DOI: 10.1074/jbc.m305656200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Cbl ubiquitin ligase has emerged as a negative regulator of receptor and non-receptor tyrosine kinases. Cbl is known to associate with the proto-oncogene product Vav, a hematopoietic-restricted Rac guanine nucleotide exchange factor, but the consequences of this interaction remain to be elucidated. Using immortalized T cell lines from Cbl(+/+) and Cbl(-/-) mice, and transfection analyses in 293T cells, we demonstrate that Vav undergoes Cbl-dependent ubiquitinylation under conditions that promote Cbl and Vav phosphorylation. Interaction with Cbl also induced the loss of phosphorylated Vav. In addition, we show that an activated Vav mutant (Vav-Y174F) is more sensitive to Cbl-dependent ubiquitinylation. We demonstrate that the Cbl-dependent ubiquitinylation of Vav requires Cbl/Vav association through phosphorylated Tyr-700 on Cbl, and also requires an intact Cbl RING finger domain. Finally, using transfection analyses in the Jurkat T cell line, we show that Cbl, but not its ubiquitin ligase mutant, can inhibit Vav-dependent signaling. Thus, our findings strongly support the role of Cbl, via its ubiquitin ligase activity, as a negative regulator of activated Vav.
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Affiliation(s)
- Yuko Miura-Shimura
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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38
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Na SY, Patra A, Scheuring Y, Marx A, Tolaini M, Kioussis D, Hemmings BA, Hemmings B, Hünig T, Bommhardt U. Constitutively active protein kinase B enhances Lck and Erk activities and influences thymocyte selection and activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:1285-96. [PMID: 12874217 DOI: 10.4049/jimmunol.171.3.1285] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protein kinase B (PKB), a serine threonine kinase is critically involved in cellular proliferation and survival. To characterize its role in T cell development in vivo, we have analyzed transgenic mice that express a membrane-targeted constitutively active version of PKB (myr PKB) in thymocytes and peripheral T cells. We report that myr PKB renders proliferative responses of thymocytes more sensitive to TCR signals by increased and sustained activation of Src kinase Lck and the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway. In addition, the proliferative response of myr PKB T cells is relatively independent of calcium mobilization and calcineurin activity. We also find that myr PKB enhances phosphorylation of glycogen synthase kinase 3, a negative regulator of NFAT and T cell activation, and the recruitment of the adapter protein Cbl-c. Interestingly, we demonstrate that upon TCR/CD3 stimulation of wild-type T cells PKB is translocated into lipid rafts, adding a new role for PKB in TCR-initiated signalosome formation in T cell activation. Localization of transgenic PKB in lipid rafts could contribute to the higher TCR sensitivity of myr PKB thymocytes which is reflected in an increase in positive selection toward the CD4 lineage and variable effects on negative selection depending on the model system analyzed. Thus, our observations clearly indicate a cross-talk between PKB and important signaling molecules downstream of TCR that modulate the thresholds of thymocyte selection and T cell activation.
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Affiliation(s)
- Shin-Young Na
- Institutes of Virology and Immunobiology, University of Würzburg, Würzburg, Germany
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39
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Thomas S, Kumar R, Preda-Pais A, Casares S, Brumeanu TD. A model for antigen-specific T-cell anergy: displacement of CD4-p56(lck) signalosome from the lipid rafts by a soluble, dimeric peptide-MHC class II chimera. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:5981-92. [PMID: 12794125 DOI: 10.4049/jimmunol.170.12.5981] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Soluble, dimeric peptide-MHC chimeras were shown to induce Ag-specific T cell anergy in vitro and in vivo. In this study, we describe a mechanism by which a soluble, dimeric peptide MHC class II chimera (DEF) induces Ag-specific T cell anergy. The anergic cells showed a displacement of the CD4-p56(lck) signaling module from the GM1-rich plasma membrane microdomains (lipid rafts), and subsequently an increase in p59(fyn) kinase activity, a dominant expression of p21 inhibitory TCR zeta-chain, and a poor phosphorylation and recruitment of zeta-associated protein of 70 kDa kinase to the TCR's immunoreceptor tyrosine-based activation motifs. The Th1 and Th2 transcription was suppressed and the cells were arrested in the Th0 stage of differentiation. Recovery from DEF anergy occurred late and spontaneously at the expense of low thresholds for activation-induced cell death. In contrast to DEF, a combination of TCR and CD4 mAbs did not induce such alterations or anergy, indicating that the ligand-mediated topology of TCR and CD4 coengagement can differentially affect the T cell function. Our results argue for a model of anergy in which the defective partitioning of signaling molecules in lipid rafts is an early, negative signaling event in T cells. Physiological ligands like DEF chimeras may provide new tools for silencing the autoimmune processes, and may also help in deciphering new mechanisms of negative regulation in T cells.
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MESH Headings
- Animals
- Apoptosis/genetics
- Apoptosis/immunology
- CD4 Antigens/biosynthesis
- CD4 Antigens/metabolism
- Clonal Anergy/genetics
- DNA-Binding Proteins/physiology
- Dimerization
- Dose-Response Relationship, Immunologic
- Down-Regulation/genetics
- Down-Regulation/immunology
- Epitopes, T-Lymphocyte/immunology
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/physiology
- Lymphocyte Activation/genetics
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/metabolism
- Membrane Microdomains/immunology
- Membrane Microdomains/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Transgenic
- Milk Proteins
- Models, Immunological
- Peptides/genetics
- Peptides/physiology
- Protein Tyrosine Phosphatases/metabolism
- Receptors, Antigen, T-Cell/antagonists & inhibitors
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/physiology
- Receptors, Interleukin-2/physiology
- Recombinant Fusion Proteins/physiology
- STAT5 Transcription Factor
- Signal Transduction/genetics
- Signal Transduction/immunology
- Solubility
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/enzymology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Th1 Cells/immunology
- Th1 Cells/metabolism
- Th2 Cells/immunology
- Th2 Cells/metabolism
- Trans-Activators/physiology
- Transcription, Genetic/genetics
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Affiliation(s)
- Sunil Thomas
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029, USA
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40
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Sharfe N, Freywald A, Toro A, Roifman CM. Ephrin-A1 induces c-Cbl phosphorylation and EphA receptor down-regulation in T cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:6024-32. [PMID: 12794130 DOI: 10.4049/jimmunol.170.12.6024] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Eph receptor tyrosine kinases are expressed by T lineage cells, and stimulation with their ligands, the ephrins, has recently been shown to modulate T cell behavior. We show that ephrin-A1 stimulation of Jurkat T cells induces tyrosine phosphorylation of EphA3 receptors and cytoplasmic proteins, including the c-cbl proto-oncogene. Cbl phosphorylation was also observed in peripheral blood T cells. In contrast, stimulation of Jurkat cells with the EphB receptor ligand ephrin-B1 does not cause Cbl phosphorylation. EphA activation also induced Cbl association with Crk-L and Crk-II adapters, but not the related Grb2 protein. Induction of Cbl phosphorylation upon EphA activation appeared to be dependent upon Src family kinase activity, as Cbl phosphorylation was selectively abrogated by the Src family inhibitor 4-amino-5(4-chlorophenyl-7-(tert-butyl)pyrazolo[3,4-d]pyrimidine, while EphA phosphorylation was unimpaired. Ephrin-A1 stimulation of Jurkat cells was also found to cause down-regulation of endogenous EphA3 receptors from the cell surface and their degradation. In accordance with the role of Cbl as a negative regulator of receptor tyrosine kinases, overexpression of wild-type Cbl, but not its 70-Z mutant, was found to down-regulate EphA receptor expression. Receptor down-regulation could also be inhibited by blockage of Src family kinase activity. Our findings show that EphA receptors can actively signal in T cells, and that Cbl performs multiple roles in this signaling pathway, functioning to transduce signals from the receptors as well as regulating activated EphA receptor expression.
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Affiliation(s)
- Nigel Sharfe
- Immunology and Allergy, Department of Pediatrics, Research Institute, Hospital for Sick Children, and University of Toronto, Toronto, Canada
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41
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Jang IK, Gu H. Negative regulation of TCR signaling and T-cell activation by selective protein degradation. Curr Opin Immunol 2003; 15:315-20. [PMID: 12787757 DOI: 10.1016/s0952-7915(03)00048-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Protein degradation was previously considered to be a nonspecific cellular process that eradicated abnormal or damaged proteins. Current evidence indicates, however, that T cells use this mechanism to selectively eliminate activated T-cell receptors (TCRs) and signaling molecules, and consequently control the duration and specificity of TCR signaling.
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Affiliation(s)
- Ihn-Kyung Jang
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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42
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Caveggion E, Continolo S, Pixley FJ, Stanley ER, Bowtell DDL, Lowell CA, Berton G. Expression and tyrosine phosphorylation of Cbl regulates macrophage chemokinetic and chemotactic movement. J Cell Physiol 2003; 195:276-89. [PMID: 12652654 DOI: 10.1002/jcp.10236] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Primary macrophages isolated from hck(-/-)fgr(-/-) mice display altered morphology and F-actin cytoskeletal structures and reduced migration. The ability of phorbol myristyl acetate (PMA), a protein kinase C activator that has been reported to increase macrophage spreading and carcinoma cell motility, to rescue these hck(-/-)fgr(-/-) defects was tested. Although PMA-treated wild-type and hck(-/-)fgr(-/-) macrophages exhibited a similar flattened, spread phenotype, PMA did not rescue the hck(-/-)fgr(-/-) macrophage migration defect. Instead, both PMA-treated wild type and hck(-/-)fgr(-/-) macrophages were defective in spontaneous and chemotactic migration and tyrosine phosphorylation of the Cbl protooncoprotein was decreased in both. Moreover, c-cbl(-/-) macrophages displayed the same impairment of motility as hck(-/-)fgr(-/-) macrophages and a similar morphology with less polarization and more dorsal ruffling than wild-type macrophages. As Hck and Fgr expression and activity were not decreased in c-cbl(-/-) macrophages, these results suggest that Cbl is likely to be an important downstream mediator of the Src family kinase-regulated macrophage motility pathway.
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Affiliation(s)
- Elena Caveggion
- Department of Pathology, Section of General Pathology, University of Verona, Verona, Italy
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43
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Graham LJ, Verí MC, DeBell KE, Noviello C, Rawat R, Jen S, Bonvini E, Rellahan B. 70Z/3 Cbl induces PLC gamma 1 activation in T lymphocytes via an alternate Lat- and Slp-76-independent signaling mechanism. Oncogene 2003; 22:2493-503. [PMID: 12717426 DOI: 10.1038/sj.onc.1206318] [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: 11/09/2022]
Abstract
The oncoprotein 70Z/3 Cbl signals in an autonomous fashion or through blockade of endogenous c-Cbl, a negative regulator of signaling. The mechanism of 70Z/3 Cbl-induced signaling was investigated by comparing the molecular requirements for 70Z/3 Cbl- and TCR-induced phospholipase C gamma 1 (PLC gamma 1) activation. 70Z/3 Cbl-induced PLC gamma 1 tyrosine phosphorylation required, in addition to the PLC gamma 1 N-terminal SH2 domain, the C-terminal SH2 and SH3 domains that were dispensable for TCR-induced phosphorylation. Deletion of the leucine zipper of 70Z/3 Cbl did not eliminate 70Z/3 Cbl-induced PLC gamma 1 phosphorylation, suggesting that blockage of c-Cbl via dimerization with 70Z/3 Cbl cannot fully explain 70Z/3 Cbl activating characteristics. The complete elimination of PLC gamma 1 phosphorylation required deleting the SH3 domain-binding region of 70Z/3 Cbl, consistent with 70Z/3 Cbl binding the PLC gamma 1 SH3 domain. 70Z/3 Cbl-induced PLC gamma 1 phosphorylation required Zap-70, as for the TCR, and the tyrosine kinase binding domain of 70Z/3 Cbl, which binds Zap-70, but did not require PLC gamma 1 binding to Lat, a crucial interaction in TCR-induced PLC gamma 1 phosphorylation. Furthermore, 70Z/3 Cbl-induced activation of NFAT, a PLC gamma 1/Ca(2+)-dependent transcriptional event, required Zap-70, but was independent of Slp-76, an adapter required for TCR-induced NFAT activation. These results suggest that 70Z/3 Cbl and PLC gamma 1 form a TCR-, Lat- and Slp-76-independent complex that leads to PLC gamma 1 phosphorylation and activation.
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Affiliation(s)
- Laurie J Graham
- Laboratory of Immunobiology, Division of Monoclonal Antibodies, Center for Biologics Evaluation and Research, Bethesda, MD 20892, USA
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44
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Abstract
The suppressor of cytokine signaling (SOCS) family of proteins is a novel class of negative feedback regulators of cytokine receptor signaling. SOCS1 is rapidly induced following stimulation by several type I and type II cytokines, and it attenuates their signaling by its ability to bind and inhibit all four of the Janus family of intracellular tyrosine kinases (JAKs). Studies from our own and other laboratories have documented another important function of SOCS1 in facilitating ubiquitination of protein substrates and their subsequent proteasomal degradation. SOCS1 also functions as a potential tumor suppressor by inhibiting several hematopoietic oncogenes. In addition to these negative regulatory functions, we have recently shown a positive regulatory role for SOCS1 in increasing the stability of major histocompatibility complex (MHC) class II proteins by preventing their degradation. These findings illustrate multiple roles for SOCS1 in cytokine receptor signaling, and provide groundwork for detailed analysis of the role of SOCS1 in pre-T cell receptor (TCR) and TCR signaling, and regulation of T helper (Th)1 and Th2 differentiation.
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Affiliation(s)
- Subburaj Ilangumaran
- Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada
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45
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Datta SK. Major peptide autoepitopes for nucleosome-centered T and B cell interaction in human and murine lupus. Ann N Y Acad Sci 2003; 987:79-90. [PMID: 12727626 DOI: 10.1111/j.1749-6632.2003.tb06035.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The potential cross-reactivity of normal T and B cells to nuclear antigens is vast, probably due to their "education" by apoptotic cell antigens in generative lymphoid organs. Despite this "nucleocentric repertoire," as we call it, the peripheral immune system normally remains tolerant or ignorant of the products of apoptosis. However, the T helper (Th) cells, and also B cells of lupus, have a regulatory defect in the expression of CD40 ligand (CD40L). A sustained hyper-expression of CD40L by lupus T cells can be triggered by sub-threshold stimuli, and is associated with impaired phosphorylation of Cbl-b, a critical downregulatory molecule in T cell signal transduction. This CD40L hyper-expression abnormally prolongs co-stimulatory signals to autoimmune B cells, and it probably instigates APC (dendritic cells, resting anti-DNA B cells, and macrophages) to present apoptotic cell autoantigens in an immunogenic fashion. We have identified the dominant nucleosomal epitopes that are critical for cognate interactions between autoimmune Th cells and anti-DNA B cells in lupus. By scanning of overlapping synthetic peptides, and by mass spectrometry of naturally processed peptides, five major epitopes in nucleosomal histones were localized, namely H1'(22-42), H2B(10-33), H3(85-105), H4(16-39), and H4(71-94). The autoimmune T cells as well as B cells of lupus recognize these epitopes, and with age, autoantibodies against the peptide epitopes cross-react with nuclear autoantigens. Moreover, the peptide autoepitopes can be promiscuously presented and recognized by lupus T cells in the context of diverse MHC alleles. This cross-reactivity opens up the possibility of developing "universally" tolerogenic peptides for therapy of lupus in humans despite their MHC diversity. Indeed, tolerogenic therapy with a single histone peptide epitope can halt the progression of established glomerulonephritis in lupus-prone mice by "tolerance spreading" that inactivates a broad spectrum of autoimmune T and B cells in concert.
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Affiliation(s)
- Syamal K Datta
- Rheumatology Division, Northwestern University Medical School, Chicago, Illinois 60611, USA.
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46
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Thien CBF, Scaife RM, Papadimitriou JM, Murphy MA, Bowtell DDL, Langdon WY. A mouse with a loss-of-function mutation in the c-Cbl TKB domain shows perturbed thymocyte signaling without enhancing the activity of the ZAP-70 tyrosine kinase. J Exp Med 2003; 197:503-13. [PMID: 12591907 PMCID: PMC2193865 DOI: 10.1084/jem.20021498] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The unique tyrosine kinase binding (TKB) domain of Cbl targets phosphorylated tyrosines on activated protein tyrosine kinases (PTKs); this targeting is considered essential for Cbl proteins to negatively regulate PTKs. Here, a loss-of-function mutation (G304E) in the c-Cbl TKB domain, first identified in Caenorhabditis elegans, was introduced into a mouse and its effects in thymocytes and T cells were studied. In marked contrast to the c-Cbl knockout mouse, we found no evidence of enhanced activity of the ZAP-70 PTK in thymocytes from the TKB domain mutant mouse. This finding contradicts the accepted mechanism of c-Cbl-mediated negative regulation, which requires TKB domain targeting of phosphotyrosine 292 in ZAP-70. However, the TKB domain mutant mouse does show aspects of enhanced signaling that parallel those of the c-Cbl knockout mouse, but these involve the constitutive activation of Rac and not enhanced PTK activity. Furthermore, the enhanced signaling in CD4(+)CD8(+) double positive thymocytes appears to be compensated by the selective down-regulation of CD3 on mature thymocytes and peripheral T cells from both strains of mutant c-Cbl mice.
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Affiliation(s)
- Christine B F Thien
- Department of Pathology, University of Western Australia, Crawley, WA 6009, Australia
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47
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Naramura M, Jang IK, Kole H, Huang F, Haines D, Gu H. c-Cbl and Cbl-b regulate T cell responsiveness by promoting ligand-induced TCR down-modulation. Nat Immunol 2002; 3:1192-9. [PMID: 12415267 DOI: 10.1038/ni855] [Citation(s) in RCA: 288] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2002] [Accepted: 09/19/2002] [Indexed: 01/08/2023]
Abstract
How Cbl family proteins regulate T cell responses is unclear. We found that c-Cbl Cbl-b double knock-out (dKO) T cells became hyperresponsive upon anti-CD3 stimulation, even though the major T cell antigen receptor (TCR) signaling pathways were not enhanced. The dKO T cells did not down-modulate surface TCR after ligand engagement, which resulted in sustained TCR signaling. However, these cells showed normal ligand-independent TCR internalization, and trafficking of internalized TCR to the lysosome compartment after ligand engagement was reduced. These findings show that Cbl family proteins negatively regulate T cell activation by promoting clearance of engaged TCR from the cell surface, a process that is apparently essential for the termination of TCR signals.
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Affiliation(s)
- Mayumi Naramura
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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48
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Paolini R, Molfetta R, Beitz LO, Zhang J, Scharenberg AM, Piccoli M, Frati L, Siraganian R, Santoni A. Activation of Syk tyrosine kinase is required for c-Cbl-mediated ubiquitination of Fcepsilon RI and Syk in RBL cells. J Biol Chem 2002; 277:36940-7. [PMID: 12145291 DOI: 10.1074/jbc.m204948200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Engagement of the high affinity receptor for IgE (FcepsilonRI) on mast cells and basophils results in FcepsilonRI beta and gamma subunits ubiquitination by an as yet undefined mechanism. Here we show that, upon FcepsilonRI engagement on RBL-2H3 cells Syk undergoes ubiquitination and Syk kinase activity is required for its own ubiquitination and that of FcepsilonRI beta and gamma chains. This requirement was demonstrated by overexpression of Syk wild-type or its kinase-dead mutant in RBL cells or using an Syk-deficient RBL-derived cell line transfected with wild-type or a kinase inactive form of Syk. We also identify c-Cbl as the E3 ligase responsible for both Syk and receptor ubiquitination. Furthermore, we demonstrate that Syk controls tyrosine phosphorylation of Syk-associated Cbl induced after receptor engagement. These data suggest a mutual regulation between Syk and Cbl activities. Finally, we show that a selective inhibitor of proteasome degradation induces persistence of tyrosine-phosphorylated receptor complexes, of activated Syk, and of FcepsilonRI-triggered degranulation. Our results provide a molecular mechanism for down-regulation of engaged receptor complexes by targeting ubiquitinated FcepsilonRI and activated Syk to the proteasome for degradation.
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Affiliation(s)
- Rossella Paolini
- Department of Experimental Medicine and Pathology, Institute Pasteur-Fondazione Cenci Bolognetti, University La Sapienza, Rome 00161, Italy.
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49
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Goh ELK, Zhu T, Leong WY, Lobie PE. c-Cbl is a negative regulator of GH-stimulated STAT5-mediated transcription. Endocrinology 2002; 143:3590-603. [PMID: 12193575 DOI: 10.1210/en.2002-220374] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We have previously demonstrated that cellular stimulation with GH results in the formation of a multiprotein signaling complex. One component of this multiprotein signaling complex is the adapter molecule c-Cbl. Here we have examined the role of c-Cbl in the mechanism of GH signal transduction. Forced expression of c-Cbl in NIH3T3 cells did not alter GH-stimulated Janus kinase 2 tyrosine phosphorylation nor GH-stimulated p44/42 MAPK activation and consequent Elk-1- mediated transcription. c-Cbl overexpression did, however, result in enhanced and prolonged GH-stimulated activation of phosphatidylinositol 3-kinase. Forced expression of c-Cbl did not affect GH-stimulated STAT5 tyrosine phosphorylation, nuclear translocation, nor binding to DNA but markedly abrogated GH-stimulated STAT5-mediated transactivation. c-Cbl overexpression resulted in increased ubiquitination and proteosomal degradation of STAT5 and increased degradation of GH-stimulated tyrosine phosphorylated STAT5. Cellular pretreatment with the proteosomal inhibitor MG132 reversed the effect of c-Cbl overexpression with prolonged duration of GH-stimulated STAT5 tyrosine phosphorylation and restoration of STAT5-mediated transcription. Thus, c-Cbl is a negative regulator of GH-stimulated STAT5-mediated transcription by direction of STAT5 for proteosomal degradation.
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Affiliation(s)
- Eyleen L K Goh
- Institute of Molecular and Cell Biology, National University of Singapore, Singapore 117609
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50
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Wang YJ, Ota S, Kataoka H, Kanamori M, Li ZY, Band H, Tanaka M, Sugimura H. Negative regulation of EphA2 receptor by Cbl. Biochem Biophys Res Commun 2002; 296:214-20. [PMID: 12147253 DOI: 10.1016/s0006-291x(02)00806-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The c-Cbl proto-oncogene product Cbl has emerged as a negative regulator of receptor and non-receptor tyrosine kinases, a function dependent on its recently identified ubiquitin ligase activity. Here, we report that EphA2, a member of Eph receptor tyrosine kinases is negatively regulated by Cbl. The negative regulation of EphA2 mediated by Cbl is dependent on the activity of EphA2, as the kinase inactive mutant of EphA2 cannot be regulated by Cbl. Moreover, a point mutation (G306E-Cbl) in TKB region of Cbl that has been reported to abolish Cbl binding to RTKs and non-receptor tyrosine kinases impaired the binding to active EphA2. The dominant negative mutant 70Z-Cbl, which has a 17-amino acids deletion in the N-boundary of the RING finger domain, defuncted negative regulatory function of Cbl to EphA2. These results demonstrate that the TKB domain and RING finger domain of Cbl are essential for this negative regulation.
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Affiliation(s)
- You jie Wang
- First Department of Pathology, Hamamatsu University School of Medicine, 1-20-1, Handayama, 431-3192, Hamamatsu, Japan
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