1
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Li X, Sun W, Huang M, Gong L, Zhang X, Zhong L, Calderon V, Bian Z, He Y, Suh WK, Li Y, Song T, Zou Y, Lian ZX, Gu H. Deficiency of CBL and CBLB ubiquitin ligases leads to hyper T follicular helper cell responses and lupus by reducing BCL6 degradation. Immunity 2024; 57:1603-1617.e7. [PMID: 38761804 DOI: 10.1016/j.immuni.2024.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 02/01/2024] [Accepted: 04/24/2024] [Indexed: 05/20/2024]
Abstract
Recent evidence reveals hyper T follicular helper (Tfh) cell responses in systemic lupus erythematosus (SLE); however, molecular mechanisms responsible for hyper Tfh cell responses and whether they cause SLE are unclear. We found that SLE patients downregulated both ubiquitin ligases, casitas B-lineage lymphoma (CBL) and CBLB (CBLs), in CD4+ T cells. T cell-specific CBLs-deficient mice developed hyper Tfh cell responses and SLE, whereas blockade of Tfh cell development in the mutant mice was sufficient to prevent SLE. ICOS was upregulated in SLE Tfh cells, whose signaling increased BCL6 by attenuating BCL6 degradation via chaperone-mediated autophagy (CMA). Conversely, CBLs restrained BCL6 expression by ubiquitinating ICOS. Blockade of BCL6 degradation was sufficient to enhance Tfh cell responses. Thus, the compromised expression of CBLs is a prevalent risk trait shared by SLE patients and causative to hyper Tfh cell responses and SLE. The ICOS-CBLs axis may be a target to treat SLE.
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Affiliation(s)
- Xin Li
- Medical Research Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong 510080, China; Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada.
| | - Weili Sun
- Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
| | - Mengxing Huang
- Medical Research Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong 510080, China
| | - Liying Gong
- Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
| | - Xiaochen Zhang
- Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Department of Microbiology, Infectiology, and Immunology, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Li Zhong
- Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
| | | | - Zhenhua Bian
- School of Biomedical Sciences and Engineering, South China University of Technology, Guangzhou International Campus, Guangzhou, Guangdong 511442, China
| | - Yi He
- Department of Rheumatology and Immunology, The Third Affiliated Hospital, Southern Medical University, Guangzhou 510630, China
| | - Woong-Kyung Suh
- Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
| | - Yang Li
- Department of Rheumatology and Immunology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong 510080, China
| | - Tengfei Song
- The Feinstein Institute for Medical Research, Manhasset, NY 11030, USA
| | - Yongrui Zou
- The Feinstein Institute for Medical Research, Manhasset, NY 11030, USA
| | - Zhe-Xiong Lian
- Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong 510080, China.
| | - Hua Gu
- Montreal Clinical Research Institute, Montreal, QC H2W 1R7, Canada; Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada; Department of Microbiology, Infectiology, and Immunology, University of Montreal, Montreal, QC H3T 1J4, Canada.
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2
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Yu H, Yang W, Cao M, Lei Q, Yuan R, Xu H, Cui Y, Chen X, Su X, Zhuo H, Lin L. Mechanism study of ubiquitination in T cell development and autoimmune disease. Front Immunol 2024; 15:1359933. [PMID: 38562929 PMCID: PMC10982411 DOI: 10.3389/fimmu.2024.1359933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/19/2024] [Indexed: 04/04/2024] Open
Abstract
T cells play critical role in multiple immune processes including antigen response, tumor immunity, inflammation, self-tolerance maintenance and autoimmune diseases et. Fetal liver or bone marrow-derived thymus-seeding progenitors (TSPs) settle in thymus and undergo T cell-lineage commitment, proliferation, T cell receptor (TCR) rearrangement, and thymic selections driven by microenvironment composed of thymic epithelial cells (TEC), dendritic cells (DC), macrophage and B cells, thus generating T cells with diverse TCR repertoire immunocompetent but not self-reactive. Additionally, some self-reactive thymocytes give rise to Treg with the help of TEC and DC, serving for immune tolerance. The sequential proliferation, cell fate decision, and selection during T cell development and self-tolerance establishment are tightly regulated to ensure the proper immune response without autoimmune reaction. There are remarkable progresses in understanding of the regulatory mechanisms regarding ubiquitination in T cell development and the establishment of self-tolerance in the past few years, which holds great potential for further therapeutic interventions in immune-related diseases.
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Affiliation(s)
- Hui Yu
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Wenyong Yang
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Min Cao
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Qingqiang Lei
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Renbin Yuan
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - He Xu
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Yuqian Cui
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Xuerui Chen
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Xu Su
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
- College of Medicine, Southwest Jiaotong University, Chengdu, China
| | - Hui Zhuo
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
| | - Liangbin Lin
- Department of Urology, Medical Research Center, Department of Neurosurgery, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, Chengdu, China
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3
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Celebi G, Kesim H, Ozer E, Kutlu O. The Effect of Dysfunctional Ubiquitin Enzymes in the Pathogenesis of Most Common Diseases. Int J Mol Sci 2020; 21:ijms21176335. [PMID: 32882786 PMCID: PMC7503467 DOI: 10.3390/ijms21176335] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 12/14/2022] Open
Abstract
Ubiquitination is a multi-step enzymatic process that involves the marking of a substrate protein by bonding a ubiquitin and protein for proteolytic degradation mainly via the ubiquitin–proteasome system (UPS). The process is regulated by three main types of enzymes, namely ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin ligases (E3). Under physiological conditions, ubiquitination is highly reversible reaction, and deubiquitinases or deubiquitinating enzymes (DUBs) can reverse the effect of E3 ligases by the removal of ubiquitin from substrate proteins, thus maintaining the protein quality control and homeostasis in the cell. The dysfunction or dysregulation of these multi-step reactions is closely related to pathogenic conditions; therefore, understanding the role of ubiquitination in diseases is highly valuable for therapeutic approaches. In this review, we first provide an overview of the molecular mechanism of ubiquitination and UPS; then, we attempt to summarize the most common diseases affecting the dysfunction or dysregulation of these mechanisms.
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Affiliation(s)
- Gizem Celebi
- Faculty of Engineering and Natural Sciences, Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Istanbul 34956, Turkey; (G.C.); (H.K.); (E.O.)
| | - Hale Kesim
- Faculty of Engineering and Natural Sciences, Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Istanbul 34956, Turkey; (G.C.); (H.K.); (E.O.)
| | - Ebru Ozer
- Faculty of Engineering and Natural Sciences, Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Istanbul 34956, Turkey; (G.C.); (H.K.); (E.O.)
| | - Ozlem Kutlu
- Sabanci University Nanotechnology Research and Application Center (SUNUM), Istanbul 34956, Turkey
- Center of Excellence for Functional Surfaces and Interfaces for Nano Diagnostics (EFSUN), Sabanci University, Istanbul 34956, Turkey
- Correspondence: ; Tel.: +90-216-483-9000 (ext. 2413)
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4
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Li X, Gong L, Gu H. Regulation of immune system development and function by Cbl-mediated ubiquitination. Immunol Rev 2020; 291:123-133. [PMID: 31402498 DOI: 10.1111/imr.12789] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 05/30/2019] [Indexed: 12/24/2022]
Abstract
Ubiquitination is a form of posttranslational protein modification that affects the activity of target proteins by regulating their intracellular degradation, trafficking, localization, and association with other regulators. Recent studies have placed protein ubiquitination as an important regulatory mode to control immune system development, function, and pathogenesis. In this review, we will mainly update the research progress from our laboratory on the roles of the Cbl family of E3 ubiquitin ligases in the development and function of lymphocytes and non-lymphoid cells. In addition, we will highlight our current understanding of the mechanisms used by this family of proteins, especially Cbl and Cbl-b, to co-ordinately regulate the function of various receptors and transcription factors in the context of immune regulation and diseases.
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Affiliation(s)
- Xin Li
- Kisoji Biotechnologies, Laval, Quebec, Canada
| | - Liying Gong
- Institut de Recherches Cliniques de Montreàl, Montreal, Quebec, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
| | - Hua Gu
- Institut de Recherches Cliniques de Montreàl, Montreal, Quebec, Canada.,Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada.,Department of Microbiology and Immunology, Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, Canada
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5
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Goetz B, An W, Mohapatra B, Zutshi N, Iseka F, Storck MD, Meza J, Sheinin Y, Band V, Band H. A novel CBL-Bflox/flox mouse model allows tissue-selective fully conditional CBL/CBL-B double-knockout: CD4-Cre mediated CBL/CBL-B deletion occurs in both T-cells and hematopoietic stem cells. Oncotarget 2018; 7:51107-51123. [PMID: 27276677 PMCID: PMC5239462 DOI: 10.18632/oncotarget.9812] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 05/10/2016] [Indexed: 11/25/2022] Open
Abstract
CBL-family ubiquitin ligases are critical negative regulators of tyrosine kinase signaling, with a clear redundancy between CBL and CBL-B evident in the immune cell and hematopoietic stem cell studies. Since CBL and CBL-B are negative regulators of immune cell activation, elimination of their function to boost immune cell activities could be beneficial in tumor immunotherapy. However, mutations of CBL are associated with human leukemias, pointing to tumor suppressor roles of CBL proteins; hence, it is critical to assess the tumor-intrinsic roles of CBL and CBL-B in cancers. This has not been possible since the only available whole-body CBL-B knockout mice exhibit constitutive tumor rejection. We engineered a new CBL-Bflox/flox mouse, combined this with an existing CBLflox/flox mouse to generate CBLflox/flox; CBL-Bflox/flox mice, and tested the tissue-specific concurrent deletion of CBL and CBL-B using the widely-used CD4-Cre transgenic allele to produce a T-cell-specific double knockout. Altered T-cell development, constitutive peripheral T-cell activation, and a lethal multi-organ immune infiltration phenotype largely resembling the previous Lck-Cre driven floxed-CBL deletion on a CBL-B knockout background establish the usefulness of the new model for tissue-specific CBL/CBL-B deletion. Unexpectedly, CD4-Cre-induced deletion in a small fraction of hematopoietic stem cells led to expansion of certain non-T-cell lineages, suggesting caution in the use of CD4-Cre for T-cell-restricted gene deletion. The establishment of a new model of concurrent tissue-selective CBL/CBL-B deletion should allow a clear assessment of the tumor-intrinsic roles of CBL/CBL-B in non-myeloid malignancies and help test the potential for CBL/CBL-B inactivation in immunotherapy of tumors.
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Affiliation(s)
- Benjamin Goetz
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Wei An
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Bhopal Mohapatra
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Departments of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Neha Zutshi
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Fany Iseka
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Matthew D Storck
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jane Meza
- Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Yuri Sheinin
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Vimla Band
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Hamid Band
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Departments of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Departments of Pharmacology and Experimental Neuroscience, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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6
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Zeng P, Ma J, Yang R, Liu YC. Immune Regulation by Ubiquitin Tagging as Checkpoint Code. Curr Top Microbiol Immunol 2017; 410:215-248. [PMID: 28929193 DOI: 10.1007/82_2017_64] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The immune system is equipped with effective machinery to mobilize its activation to defend invading microorganisms, and at the same time, to refrain from attacking its own tissues to maintain immune tolerance. The balance of activation and tolerance is tightly controlled by diverse mechanisms, since breakdown of tolerance could result in disastrous consequences such as the development of autoimmune diseases. One of the mechanisms is by the means of protein ubiquitination, which involves the process of tagging a small peptide ubiquitin to protein substrates. E3 ubiquitin ligases are responsible for catalyzing the final step of ubiquitin-substrate conjugation by specifically recognizing substrates to determine their fates of degradation or functional modification. The ubiquitination process is reversible, which is carried out by deubiquitinating enzymes to release the ubiquitin molecule from the conjugated substrates. Protein ubiquitination and deubiquitination serve as checkpoint codes in many key steps of lymphocyte regulation including the development, activation, differentiation, and tolerance induction. In this chapter, we will discuss a few E3 ligases and deubiquitinating enzymes that are important in controlling immune responses, with emphasis on their roles in T cells.
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Affiliation(s)
- Peng Zeng
- Institute for Immunology, Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Jieyu Ma
- Institute for Immunology, Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Runqing Yang
- Institute for Immunology, Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Yun-Cai Liu
- Institute for Immunology, Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China. .,Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, 92037, USA.
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7
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Carson WF, Guernsey LA, Singh A, Secor ER, Wohlfert EA, Clark RB, Schramm CM, Kunkel SL, Thrall RS. Cbl-b Deficiency in Mice Results in Exacerbation of Acute and Chronic Stages of Allergic Asthma. Front Immunol 2015; 6:592. [PMID: 26635806 PMCID: PMC4653292 DOI: 10.3389/fimmu.2015.00592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 11/04/2015] [Indexed: 01/21/2023] Open
Abstract
Mice sensitized to ovalbumin (OVA) develop allergic airway disease (AAD) with short-term daily OVA aerosol challenge; inflammation resolves with long-term OVA aerosol exposure, resulting in local inhalational tolerance (LIT). Cbl-b is an E3 ubiquitin ligase involved with CD28 signaling; Cbl-b−/− effector T cells are resistant to regulatory T cell-mediated suppression in vitro and in vivo. The present study utilized Cbl-b−/− mice to investigate the role of Cbl-b in the development of AAD and LIT. Cbl-b−/− mice exhibited increased airway inflammation during AAD, which failed to resolve with long-term OVA aerosol exposure. Exacerbation of inflammation in Cbl-b−/− mice correlated with increased proinflammatory cytokine levels and expansion of effector T cells in the BAL during AAD, but did not result in either a modulation of lymphocyte subsets in systemic tissues or in OVA-specific IgE in serum. These results implicate a role for Cbl-b in the resolution of allergic airway inflammation.
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Affiliation(s)
- William F Carson
- Department of Pathology, University of Michigan , Ann Arbor, MI , USA
| | - Linda A Guernsey
- Department of Immunology, University of Connecticut Health Center , Farmington, CT , USA
| | - Anurag Singh
- Department of Immunology, University of Connecticut Health Center , Farmington, CT , USA
| | - Eric R Secor
- Department of Immunology, University of Connecticut Health Center , Farmington, CT , USA
| | - Elizabeth A Wohlfert
- Department of Pediatrics, University of Connecticut Health Center , Farmington, CT , USA
| | - Robert B Clark
- Department of Immunology, University of Connecticut Health Center , Farmington, CT , USA
| | - Craig M Schramm
- Department of Microbiology and Immunology, University at Buffalo , Buffalo, NY , USA
| | - Steven L Kunkel
- Department of Pathology, University of Michigan , Ann Arbor, MI , USA
| | - Roger S Thrall
- Department of Immunology, University of Connecticut Health Center , Farmington, CT , USA
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8
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Martin-Blanco N, Jiménez Teja D, Bretones G, Borroto A, Caraballo M, Screpanti I, León J, Alarcón B, Canelles M. CD3ε recruits Numb to promote TCR degradation. Int Immunol 2015; 28:127-37. [PMID: 26507128 DOI: 10.1093/intimm/dxv060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 10/15/2015] [Indexed: 01/05/2023] Open
Abstract
Modulation of TCR signaling upon ligand binding is achieved by changes in the equilibrium between TCR degradation, recycling and synthesis; surprisingly, the molecular mechanism of such an important process is not fully understood. Here, we describe the role of a new player in the mediation of TCR degradation: the endocytic adaptor Numb. Our data show that Numb inhibition leads to abnormal intracellular distribution and defective TCR degradation in mature T lymphocytes. In addition, we find that Numb simultaneously binds to both Cbl and a site within CD3ε that overlaps with the Nck binding site. As a result, Cbl couples specifically to the CD3ε chain to mediate TCR degradation. The present study unveils a novel role of Numb that lies at the heart of TCR signaling initiation and termination.
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Affiliation(s)
- Nadia Martin-Blanco
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Daniel Jiménez Teja
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain
| | - Gabriel Bretones
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC-SODERCAN, Santander, Spain
| | - Aldo Borroto
- Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Michael Caraballo
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain
| | - Isabella Screpanti
- Laboratory of Molecular Pathology, Department of Experimental Medicine, Sapienza University of Rome, Viale Regina Elena, 324, 00161 Rome, Italy
| | - Javier León
- Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC-SODERCAN, Santander, Spain
| | - Balbino Alarcón
- Centro de Biología Molecular Severo Ochoa, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Matilde Canelles
- Instituto de Parasitología y Biomedicina, CSIC, P. T. Ciencias de la Salud, 18100 Granada, Spain
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9
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Iguchi T, Aoki K, Ikawa T, Taoka M, Taya C, Yoshitani H, Toma-Hirano M, Koiwai O, Isobe T, Kawamoto H, Masai H, Miyatake S. BTB-ZF Protein Znf131 Regulates Cell Growth of Developing and Mature T Cells. THE JOURNAL OF IMMUNOLOGY 2015; 195:982-93. [PMID: 26136427 DOI: 10.4049/jimmunol.1500602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/31/2015] [Indexed: 02/01/2023]
Abstract
Many members of the BTB-ZF family have been shown to play important roles in lymphocyte development and function. The role of zinc finger Znf131 (also known as Zbtb35) in T cell lineage was elucidated through the production of mice with floxed allele to disrupt at different stages of development. In this article, we present that Znf131 is critical for T cell development during double-negative to double-positive stage, with which significant cell expansion triggered by the pre-TCR signal is coupled. In mature T cells, Znf131 is required for the activation of effector genes, as well as robust proliferation induced upon TCR signal. One of the cyclin-dependent kinase inhibitors, p21(Cip1) encoded by cdkn1a gene, is one of the targets of Znf131. The regulation of T cell proliferation by Znf131 is in part attributed to its suppression on the expression of p21(Cip1).
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Affiliation(s)
- Tomohiro Iguchi
- Laboratory of Self Defense Gene Regulation, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan; Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda 278-8510, Japan
| | - Kazuhisa Aoki
- Laboratory of Self Defense Gene Regulation, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Tomokatsu Ikawa
- Young Chief Investigators Laboratory for Immune Regeneration, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Masato Taoka
- Laboratory of Biochemistry, Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Choji Taya
- Animal Research Division, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Hiroshi Yoshitani
- Laboratory of Self Defense Gene Regulation, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Makiko Toma-Hirano
- Department of Otolaryngology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Osamu Koiwai
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda 278-8510, Japan
| | - Toshiaki Isobe
- Laboratory of Biochemistry, Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Hiroshi Kawamoto
- Department of Immunology, Field of Regeneration Control, Institute of Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan; and
| | - Hisao Masai
- Genome Dynamics Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Shoichiro Miyatake
- Laboratory of Self Defense Gene Regulation, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan;
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10
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Naramura M, Band V, Band H. Indispensable roles of mammalian Cbl family proteins as negative regulators of protein tyrosine kinase signaling: Insights from in vivo models. Commun Integr Biol 2011; 4:159-62. [PMID: 21655429 DOI: 10.4161/cib.4.2.14716] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/04/2011] [Indexed: 01/13/2023] Open
Abstract
All higher eukaryotes utilize protein tyrosine kinases (PTKs) as molecular switches to control a variety of cellular signals. Notably, many PTKs have been identified as proto-oncogenes whose aberrant expression, mutations or co-option by pathogens can lead to human malignancies. Thus, it is obvious that PTK functions must be precisely regulated in order to maintain homeostasis of an organism. Investigations over the past fifteen years have revealed that members of the Cbl family proteins can serve as negative regulators of PTK signaling, and biochemical and cell biological studies have unraveled the mechanistic basis of this regulation. Yet, it is only recently that the field has begun to appreciate the real significance of this novel regulatory apparatus in shaping PTK-mediated signaling in organismic contexts and in human diseases. Here, we discuss recent progress in murine models that are beginning to provide insights into the critical roles of Cbl proteins in physiological pathways, with important implications in understanding how aberrations of Cbl proteins contribute to oncogenesis.
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Affiliation(s)
- Mayumi Naramura
- Eppley Institute for Research in Cancer and Allied Diseases; College of Medicine; University of Nebraska Medical Center; Omaha, NE USA
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11
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Billard MJ, Gruver AL, Sempowski GD. Acute endotoxin-induced thymic atrophy is characterized by intrathymic inflammatory and wound healing responses. PLoS One 2011; 6:e17940. [PMID: 21437240 PMCID: PMC3060875 DOI: 10.1371/journal.pone.0017940] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 02/18/2011] [Indexed: 11/28/2022] Open
Abstract
Background Productive thymopoiesis is essential for a robust and healthy immune system.
Thymus unfortunately is acutely sensitive to stress resulting in involution
and decreased T cell production. Thymic involution is a complication of many
clinical settings, including infection, malnutrition, starvation, and
irradiation or immunosuppressive therapies. Systemic rises in
glucocorticoids and inflammatory cytokines are known to contribute to thymic
atrophy. Little is known, however, about intrathymic mechanisms that may
actively contribute to thymus atrophy or initiate thymic recovery following
stress events. Methodology/Principal Findings Phenotypic, histologic and transcriptome/pathway analysis of murine thymic
tissue during the early stages of endotoxemia-induced thymic involution was
performed to identify putative mechanisms that drive thymic involution
during stress. Thymus atrophy in this murine model was confirmed by
down-regulation of genes involved in T cell development, cell activation,
and cell cycle progression, correlating with observed phenotypic and
histologic thymus involution. Significant gene changes support the
hypothesis that multiple key intrathymic pathways are differentially
activated during stress-induced thymic involution. These included direct
activation of thymus tissue by LPS through TLR signaling, local expression
of inflammatory cytokines, inhibition of T cell signaling, and induction of
wound healing/tissue remodeling. Conclusions/Significance Taken together, these observations demonstrated that in addition to the
classic systemic response, a direct intrathymic response to endotoxin
challenge concurrently contributes to thymic involution during endotoxemia.
These findings are a substantial advancement over current understanding of
thymus response to stress and may lead to the development of novel
therapeutic approaches to ameliorate immune deficiency associated with
stress events.
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Affiliation(s)
- Matthew J. Billard
- Department of Biostatistics & Bioinformatics, Duke University Medical
Center, Durham, North Carolina, United States of America
| | - Amanda L. Gruver
- Department of Medicine, Department of Pathology, and the Duke University
Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina,
United States of America
| | - Gregory D. Sempowski
- Department of Medicine, Department of Pathology, and the Duke University
Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina,
United States of America
- * E-mail:
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Whiting CC, Su LL, Lin JT, Fathman CG. GRAIL: a unique mediator of CD4 T-lymphocyte unresponsiveness. FEBS J 2010; 278:47-58. [PMID: 21078124 DOI: 10.1111/j.1742-4658.2010.07922.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
GRAIL (gene related to anergy in lymphocytes, also known as RNF128), an ubiquitin-protein ligase (E3), utilizes a unique single transmembrane protein with a split-function motif, and is an important gatekeeper of T-cell unresponsiveness. Although it may play a role in other CD4 T-cell functions including activation, survival and differentiation, GRAIL is most well characterized as a negative regulator of T-cell receptor responsiveness and cytokine production. Here, we review the recent literature on this remarkable E3 in the regulation of human and mouse CD4 T-cell unresponsiveness.
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Affiliation(s)
- Chan C Whiting
- Department of Medicine, Stanford University, Stanford, CA 94305, USA
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13
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The endocytic adaptor Numb regulates thymus size by modulating pre-TCR signaling during asymmetric division. Blood 2010; 116:1705-14. [PMID: 20530794 DOI: 10.1182/blood-2009-10-246777] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Stem cells must proliferate and differentiate to generate the lineages that shape mature organs; understanding these 2 processes and their interaction is one of the central themes in current biomedicine. An intriguing aspect is asymmetric division, by which 2 daughter cells with different fates are generated. Several cell fate determinants participate in asymmetric division, with the endocytic adaptor Numb as the best-known example. Here, we have explored the role of asymmetric division in thymocyte development, visualizing the differential segregation of Numb and pre-TCR in thymic precursors. Analysis of mice where Numb had been inhibited by expressing a dominant negative revealed enhanced pre-T-cell receptor (TCR) signaling and a smaller thymus. Conversely, Numb overexpression resulted in loss of asymmetric division and a larger thymus. The conclusion is that Numb determines the levels of pre-TCR signaling in dividing thymocytes and, ultimately, the size of the pool from which mature T lymphocytes are selected.
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14
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Gruber T, Pfeifhofer-Obermair C, Baier G. PKCtheta is necessary for efficient activation of NFkappaB, NFAT, and AP-1 during positive selection of thymocytes. Immunol Lett 2010; 132:6-11. [PMID: 20433868 PMCID: PMC2937209 DOI: 10.1016/j.imlet.2010.04.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 04/06/2010] [Accepted: 04/20/2010] [Indexed: 01/25/2023]
Abstract
While it has been shown in several publications that the serine-threonine kinase PKCθ is required for efficient activation of mature T lymphocytes, the role of PKCθ in T cell development in the thymus is somewhat controversial. In this study, using knockout mice, we show that PKCθ is important in positive selection. The thymus of PKCθ−/− animals contains significantly less mature single positive T cells compared to wild-type controls. Biochemically, PKCθ deficient thymocytes show defective activation of the transcription factors AP-1, NFAT and NFκB as well as impaired phosphorylation of the MAP kinase ERK after T cell receptor stimulation in vitro. Together, these results reveal a crucial role of PKCθ in positive selection of thymocytes in a pathway leading to the activation of ERK, AP-1, NFAT, and NFκB.
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Affiliation(s)
- Thomas Gruber
- Department of Medical Genetics, Clinical and Molecular Pharmacology, Medical University of Innsbruck, Schöpfstrasse 41, A-6020 Innsbruck, Austria.
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15
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Thien CBF, Dagger SA, Steer JH, Koentgen F, Jansen ES, Scott CL, Langdon WY. c-Cbl promotes T cell receptor-induced thymocyte apoptosis by activating the phosphatidylinositol 3-kinase/Akt pathway. J Biol Chem 2010; 285:10969-81. [PMID: 20133944 DOI: 10.1074/jbc.m109.094920] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ability of thymocytes to assess T cell receptor (TCR) signaling strength and initiate the appropriate downstream response is crucial for determining their fate. We have previously shown that a c-Cbl RING finger mutant knock-in mouse, in which the E3 ubiquitin ligase activity of c-Cbl is inactivated, is highly sensitive to TCR-induced death signals that cause thymic deletion. This high intensity signal involves the enhanced tyrosine phosphorylation of the mutant c-Cbl protein promoting a marked increase in the activation of Akt. Here we show that this high intensity signal in c-Cbl RING finger mutant thymocytes also promotes the enhanced induction of two mediators of TCR-directed thymocyte apoptosis, Nur77 and the pro-apoptotic Bcl-2 family member, Bim. In contrast, a knock-in mouse harboring a mutation at Tyr-737, the site in c-Cbl that activates phosphatidylinositol 3-kinase, shows reduced TCR-mediated responses including suppression of Akt activation, a reduced induction of Nur77 and Bim, and greater resistance to thymocyte death. These findings identify tyrosine-phosphorylated c-Cbl as a critical sensor of TCR signal strength that regulates the engagement of death-promoting signals.
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Affiliation(s)
- Christine B F Thien
- School of Pathology and Laboratory Medicine, University of Western Australia, Crawley 6009,Western Australia
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16
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Morley SC, Weber KS, Kao H, Allen PM. Protein kinase C-theta is required for efficient positive selection. THE JOURNAL OF IMMUNOLOGY 2008; 181:4696-708. [PMID: 18802072 DOI: 10.4049/jimmunol.181.7.4696] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protein kinase C-theta (PKCtheta) is critical for TCR-initiated signaling in mature T cells, but initial reports found no requirement for PKCtheta in thymocyte development. Thymocytes and peripheral T cells utilize many of the same signaling components and, given the significant role of PKCtheta in peripheral T cells, it was surprising that it was not involved at all in TCR signaling in thymocytes. We decided to re-evaluate the role of PKCtheta in thymocyte development using the well-characterized class II-restricted n3.L2 TCR-transgenic TCR model. Analysis of n3.L2 PKCtheta(-/-) mice revealed a defect in thymocyte-positive selection, resulting in a 50% reduction in the generation of n3.L2 CD4 single-positive thymocytes and n3.L2 CD4 mature T cells. Competition between n3.L2 WT and n3.L2 PKCtheta(-/-) thymocytes in bone marrow chimeras revealed a more dramatic defect, with a >80% reduction in generation of n3.L2 CD4 single-positive thymocytes derived from PKCtheta(-/-) mice. Inefficient positive selection of n3.L2 PKCtheta(-/-) CD4 single-positive cells resulted from "weaker" signaling through the TCR and correlated with diminished ERK activation. The defect in positive selection was not complete in the PKCtheta(-/-) mice, most likely accounted for by compensation by other PKC isoforms not evident in peripheral cells. Similar decreased positive selection of both CD4 and CD8 single-positive thymocytes was also seen in nontransgenic PKCtheta(-/-) mice. These findings now place PKCtheta as a key signaling molecule in the positive selection of thymocytes as well as in the activation of mature T cells.
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Affiliation(s)
- Sharon Celeste Morley
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
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17
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Ouchida R, Yamasaki S, Hikida M, Masuda K, Kawamura K, Wada A, Mochizuki S, Tagawa M, Sakamoto A, Hatano M, Tokuhisa T, Koseki H, Saito T, Kurosaki T, Wang JY. A Lysosomal Protein Negatively Regulates Surface T Cell Antigen Receptor Expression by Promoting CD3ζ-Chain Degradation. Immunity 2008; 29:33-43. [PMID: 18619870 DOI: 10.1016/j.immuni.2008.04.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 02/22/2008] [Accepted: 04/14/2008] [Indexed: 11/29/2022]
Affiliation(s)
- Rika Ouchida
- Laboratory for Immune Diversity, Research Center for Allergy and Immunology, RIKEN Yokohama Institute, Yokohama 230-0045, Japan
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18
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T-cell receptor-induced NF-kappaB activation is negatively regulated by E3 ubiquitin ligase Cbl-b. Mol Cell Biol 2008; 28:2470-80. [PMID: 18227156 DOI: 10.1128/mcb.01505-07] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
It has previously been shown that E3 ubiquitin ligase Casitas B-lineage lymphoma-b (Cbl-b) negatively regulates T-cell activation, but the molecular mechanism(s) underlying this inhibition is not completely defined. In this study, we report that the loss of Cbl-b selectively results in aberrant activation of NF-kappaB upon T-cell antigen receptor (TCR) ligation, which is mediated by phosphatidylinositol 3-kinase (PI3-K)/Akt and protein kinase C-theta (PKC-theta). TCR-induced hyperactivation of Akt in the absence of Cbl-b may potentiate the formation of caspase recruitment domain-containing membrane-associated guanylate kinase protein 1 (CARMA1)-B-cell lymphoma/leukemia 10 (Bcl10)-mucosa-associated lymphatic tissue 1(MALT1) (CBM) complex, which appears to be independent of PKC-theta. Cbl-b associates with PKC-theta upon TCR stimulation and regulates TCR-induced PKC-theta activation via Vav-1, which couples PKC-theta to PI3-K and allows it to be phosphorylated. PKC-theta then couples IkappaB kinases (IKKs) to the CBM complex, resulting in the activation of the IKK complex. Therefore, our data provide the first evidence to demonstrate that the down-regulation of TCR-induced NF-kappaB activation by Cbl-b is mediated coordinately by both Akt-dependent and PKC-theta-dependent signaling pathways in primary T cells.
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19
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Control of virus-specific CD8+ T-cell exhaustion and immune-mediated pathology by E3 ubiquitin ligase Cbl-b during chronic viral infection. J Virol 2008; 82:3353-68. [PMID: 18199651 DOI: 10.1128/jvi.01350-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
A characteristic feature in the immune response to many persistent viral infections is the dysfunction or deletion of antigen-specific T cells (exhaustion). This down-regulation of virus-specific T-cell response represents a critical control mechanism that exists within T-cell activation pathways to prevent lethal disease by inappropriate responses against disseminating virus infections. However, the molecular mechanisms by which the immune system determines whether to mount a full response to such infections remain largely unexplored. Here, we have established that in the murine lymphocytic choriomeningitis virus (LCMV) model, induction of the T-cell receptor signaling inhibitor molecule E3 ligase Cbl-b is critically involved in this decision. In particular, our data revealed that Cbl-b controls the program responsible for T-cell tolerance (exhaustion) induction during a chronic viral infection. Thus, Cbl-b(-/-) mice infected with a low dose of LCMV Docile mount a strong CD8(+) T-cell response that rapidly clears the infection, and the animals remain healthy; in contrast, down-regulation of the epitope-specific CD8(+) T-cell population in persistently infected Cbl-b(-/-) mice, compared to that in chronically infected B6 mice, was significantly delayed, and this was associated with increased morbidity and eventual death in nearly 20% of the animals. Interestingly, infection of Cbl-b(-/-) mice with a moderate virus dose resulted in rapid death with 100% mortality by 7 to 8 days after infection, caused by a dysregulated antiviral T-cell response, whereas the infected B6 mice survived and remained healthy. In conclusion, our results suggest that Cbl-b is critically involved in T-cell exhaustion and prevention of lethal disease.
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Abstract
Directing both innate and adaptive immune responses against foreign pathogens with correct timing, location and specificity is a fundamental objective for the immune system. Full activation of CD4+ T cells requires the binding of peptide-MHC complexes coupled with accessory signals provided by the antigen-presenting cell. However, aberrant activation of the T-cell receptor alone in mature T cells can produce a long-lived state of functional unresponsiveness, known as anergy. Recent studies probing both immune signalling pathways and the ubiquitin-proteasome system have helped to refine and elaborate current models for the molecular mechanisms underlying T-cell anergy. Controlling anergy induction and maintenance will be a key component in the future to mitigate unwanted T-cell activation that leads to autoimmune disease.
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Affiliation(s)
- C Garrison Fathman
- Stanford University School of Medicine, Department of Medicine, Division of Immunology and Rheumatology, CCSR Building, 269 Campus Drive, Room 2225, Stanford, California 94305-5166, USA.
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Loeser S, Penninger JM. Regulation of peripheral T cell tolerance by the E3 ubiquitin ligase Cbl-b. Semin Immunol 2007; 19:206-14. [PMID: 17391982 DOI: 10.1016/j.smim.2007.02.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 02/16/2007] [Indexed: 02/07/2023]
Abstract
The family of the Casitas B-lineage Lymphoma (Cbl) proteins, c-Cbl, Cbl-b, and Cbl-3, function as E3 ubiquitin ligases and molecular adaptors. In particular, Cbl-b acts as a gatekeeper in T cell activation that controls activation thresholds and the requirement for co-stimulation. Loss of Cbl-b expression renders animals susceptible to antigen-triggered autoimmunity suggesting that Cbl-b is a key autoimmunity gene. In addition, Cbl-b plays a critical role in T cell anergy and escape from regulatory T cells (Treg) suppression. Modulation of Cbl-b might provide us with a unique opportunity for future immune treatment of human disorders such as autoimmunity, immunodeficiency, or cancer.
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Affiliation(s)
- Stefanie Loeser
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohrgasse 3, A-1030 Vienna, Austria.
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