1
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Li H, Hostager BS, Arkee T, Bishop GA. Multiple mechanisms for TRAF3-mediated regulation of the T cell costimulatory receptor GITR. J Biol Chem 2021; 297:101097. [PMID: 34418432 PMCID: PMC8441216 DOI: 10.1016/j.jbc.2021.101097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/10/2021] [Accepted: 08/17/2021] [Indexed: 11/28/2022] Open
Abstract
Tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) plays context-specific roles in multiple receptor-mediated signaling pathways in different cell types. Mice lacking TRAF3 in T cells display defective T-cell-mediated immune responses to immunization and infection and demonstrate defective early signaling via the TCR complex. However, the role of TRAF3 in the function of GITR/TNFRSF18, an important costimulatory member of the TNFR superfamily, is unclear. Here we investigated the impact of T cell TRAF3 status on both GITR expression and activation of specific kinases in the GITR signaling pathway in T cells. Our results indicate that TRAF3 negatively regulates GITR functions in several ways. First, expression of GITR protein was elevated in TRAF3-deficient T cells, resulting from both transcriptional and posttranslational regulation that led to greater GITR transcript levels, as well as enhanced GITR protein stability. TRAF3 associated with T cell GITR in a manner dependent upon GITR ligation. TRAF3 also inhibited several events of the GITR mediated early signaling cascade, in a manner independent of recruitment of phosphatases, a mechanism by which TRAF3 inhibits signaling through several other cytokine receptors. These results add new information to our understanding of GITR signaling and function in T cells, which is relevant to the potential use of GITR to enhance immune therapies.
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Affiliation(s)
- Hanzeng Li
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, USA
| | - Bruce S Hostager
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, USA
| | - Tina Arkee
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, USA; Medical Scientist Training Program, The University of Iowa, Iowa City, Iowa, USA
| | - Gail A Bishop
- Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, USA; Medical Scientist Training Program, The University of Iowa, Iowa City, Iowa, USA; Department of Internal Medicine, The University of Iowa, Iowa City, Iowa, USA; Research, Iowa City VA Medical Center, Iowa City, Iowa, USA.
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2
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Workman LM, Zhang L, Fan Y, Zhang W, Habelhah H. TRAF2 Ser-11 Phosphorylation Promotes Cytosolic Translocation of the CD40 Complex To Regulate Downstream Signaling Pathways. Mol Cell Biol 2020; 40:e00429-19. [PMID: 32041822 PMCID: PMC7156217 DOI: 10.1128/mcb.00429-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 11/14/2019] [Accepted: 01/29/2020] [Indexed: 11/20/2022] Open
Abstract
CD40 plays an important role in immune responses by activating the c-Jun N-terminal protein kinase (JNK) and NF-κB pathways; however, the precise mechanisms governing the spatiotemporal activation of these two signaling pathways are not fully understood. Here, using four different TRAF2-deficient cell lines (A20.2J, CH12.LX, HAP1, and mouse embryonic fibroblasts [MEFs]) reconstituted with wild-type or phosphorylation mutant forms of TRAF2, along with immunoprecipitation, immunoblotting, gene expression, and immunofluorescence analyses, we report that CD40 ligation elicits TANK-binding kinase 1 (TBK1)-mediated phosphorylation of TRAF2 at Ser-11. This phosphorylation interfered with the interaction between TRAF2's RING domain and membrane phospholipids and enabled translocation of the TRAF2 complex from CD40 to the cytoplasm. We also observed that this cytoplasmic translocation is required for full activation of the JNK pathway and the secondary phase of the NF-κB pathway. Moreover, we found that in the absence of Ser-11 phosphorylation, the TRAF2 RING domain interacts with phospholipids, leading to the translocation of the TRAF2 complex to lipid rafts, resulting in its degradation and activation of the noncanonical NF-κB pathway. Thus, our results provide new insights into the CD40 signaling mechanisms whereby Ser-11 phosphorylation controls RING domain-dependent subcellular localization of TRAF2 to modulate the spatiotemporal activation of the JNK and NF-κB pathways.
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Affiliation(s)
- Lauren M Workman
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Laiqun Zhang
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Yumei Fan
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Science, Hebei Normal University, Shijiazhuang, People's Republic of China
| | - Weizhou Zhang
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Hasem Habelhah
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
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3
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Arkee T, Bishop GA. TRAF family molecules in T cells: Multiple receptors and functions. J Leukoc Biol 2019; 107:907-915. [PMID: 31749173 DOI: 10.1002/jlb.2mr1119-397r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/05/2019] [Accepted: 11/07/2019] [Indexed: 12/13/2022] Open
Abstract
The TNFR superfamily of receptors, the major focus of the recent TNFR Superfamily Conference held in June 2019, employ the TNFR-associated factor (TRAF) family of adaptor proteins in key aspects of their signaling pathways. Although many early studies investigated TRAF functions via exogenous overexpression in nonhematopoietic cell lines, it has subsequently become clear that whereas TRAFs share some overlap in function, each also plays unique biologic roles, that can be highly context dependent. This brief review summarizes the current state of knowledge of functions of each of the TRAF molecules that mediate important functions in T lymphocytes: TRAFs 1, 2, 3, 5, and 6. Due to our current appreciation of the contextual nature of TRAF function, our focus is upon findings made specifically in T lymphocytes. Key T cell functions for each TRAF are detailed, as well as future knowledge gaps of interest and importance.
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Affiliation(s)
- Tina Arkee
- Graduate Program in Immunology, The University of Iowa, Iowa City, Iowa, USA.,Medical Scientist Training Program, The University of Iowa, Iowa City, Iowa, USA
| | - Gail A Bishop
- Graduate Program in Immunology, The University of Iowa, Iowa City, Iowa, USA.,Medical Scientist Training Program, The University of Iowa, Iowa City, Iowa, USA.,Depts. of Microbiology & Immunology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.,Iowa City VA Medical Center, Iowa City, Iowa, USA
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4
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Yao Y, Huang W, Li X, Li X, Qian J, Han H, Sun H, An X, Lu L, Zhao H. Tespa1 Deficiency Dampens Thymus-Dependent B-Cell Activation and Attenuates Collagen-Induced Arthritis in Mice. Front Immunol 2018; 9:965. [PMID: 29867947 PMCID: PMC5960706 DOI: 10.3389/fimmu.2018.00965] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/18/2018] [Indexed: 12/21/2022] Open
Abstract
Thymocyte-expressed, positive selection-associated 1 (Tespa1) plays an important role in both T cell receptor (TCR)-driven thymocyte development and in the FcεRI-mediated activation of mast cells. Herein, we show that lack of Tespa1 does not impair B cell development but dampens the in vitro activation and proliferation of B cells induced by T cell-dependent (TD) antigens, significantly reduces serum antibody concentrations in vivo, and impairs germinal center formation in both aged and TD antigen-immunized mice. We also provide evidence that dysregulated signaling in Tespa1-deficient B cells may be linked to CD40-induced TRAF6 degradation, and subsequent effects on 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase gamma-2 (PLCγ2) phosphorylation, MAPK activation, and calcium influx. Furthermore, we demonstrate that Tespa1 plays a critical role in pathogenic B cells, since Tespa1-deficient chimeric mice showed a lower incidence and clinical disease severity of collagen-induced arthritis. Overall, our study demonstrates that Tespa1 is essential for TD B cell responses, and suggests an important role for Tespa1 during the development of autoimmune arthritis.
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Affiliation(s)
- Yunliang Yao
- Program in Molecular and Translational Medicine (PMTM), School of Medicine, Huzhou University, Huzhou, China
| | - Wei Huang
- The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaoyu Li
- Program in Molecular and Translational Medicine (PMTM), School of Medicine, Huzhou University, Huzhou, China
| | - Xiawei Li
- The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jin Qian
- Program in Molecular and Translational Medicine (PMTM), School of Medicine, Huzhou University, Huzhou, China
| | - Hui Han
- First Affiliated Hospital, Huzhou University, Huzhou, China
| | - Hui Sun
- First Affiliated Hospital, Huzhou University, Huzhou, China
| | - Xiangli An
- Program in Molecular and Translational Medicine (PMTM), School of Medicine, Huzhou University, Huzhou, China
| | - Linrong Lu
- School of Medicine, Institute of Immunology, Zhejiang University, Hangzhou, China
| | - Hongxing Zhao
- First Affiliated Hospital, Huzhou University, Huzhou, China
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5
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Abstract
The signaling adapter protein tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) is both modified by and contributes to several types of ubiquitination events. TRAF3 plays a variety of context-dependent regulatory roles in all types of immune cells. In B lymphocytes, TRAF3 contributes to regulation of signaling by members of both the TNFR superfamily and innate immune receptors. TRAF3 also plays a unique cell type-specific and critical role in the restraint of B-cell homeostatic survival, a role with important implications for both B-cell differentiation and the pathogenesis of B-cell malignancies. This review focuses upon the relationship between ubiquitin and TRAF3, and how this contributes to multiple functions of TRAF3 in the regulation of signal transduction, transcriptional activation, and effector functions of B lymphocytes.
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Affiliation(s)
- Wai W Lin
- The Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA
| | - Bruce S Hostager
- Department of Pediatrics, University of Iowa, Iowa City, IA, USA
| | - Gail A Bishop
- The Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA.,Department of Microbiology, University of Iowa, Iowa City, IA, USA.,Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.,VA Medical Center, University of Iowa, Iowa City, IA, USA
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6
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Bishop GA. TRAF3 as a powerful and multitalented regulator of lymphocyte functions. J Leukoc Biol 2016; 100:919-926. [PMID: 27154354 DOI: 10.1189/jlb.2mr0216-063r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 04/07/2016] [Indexed: 12/12/2022] Open
Abstract
This review summarizes the current state of knowledge regarding the roles of the signaling adapter protein tumor necrosis factor receptor (TNFR)-associated factor 3 in regulating the functions of B and T lymphocytes. In B lymphocytes, TNFR-associated factor 3 inhibits signaling by TNFR superfamily receptors, Toll-like receptors, and interleukin-6R. In contrast, signaling to B cells by the virally encoded oncogenic protein latent membrane protein 1 is promoted by TNFR-associated factor 3. An important B cell-specific role for TNFR-associated factor 3 is the inhibition of homeostatic survival, directly relevant to the common occurrence of TNFR-associated factor 3 mutations in human B cell malignancies. TNFR-associated factor 3 was recently found to be a resident nuclear protein in B cells, where it interacts with and inhibits gene expression mediated by the cAMP response element-binding protein transcription complex, including expression of the prosurvival protein myeloid leukemia cell differentiation protein 1. In T lymphocytes, TNFR-associated factor 3 is required for normal signaling by the T cell antigen receptor, while inhibiting signaling by the interleukin-2 receptor. Cytoplasmic TNFR -associated factor 3 restrains nuclear factor-κB2 activation in both T and B cells. Clinical implications and future directions for the study of this context-dependent signaling regulator are discussed.
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Affiliation(s)
- Gail A Bishop
- Department of Microbiology, The University of Iowa, Iowa City, Iowa, USA; .,Department of Internal Medicine, The University of Iowa, Iowa City, Iowa, USA; and .,Department of Veterans Affairs Medical Center, Iowa City, Iowa, USA
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7
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Tumor Necrosis Factor Receptor Associated Factors (TRAFs) 2 and 3 Form a Transcriptional Complex with Phosho-RNA Polymerase II and p65 in CD40 Ligand Activated Neuro2a Cells. Mol Neurobiol 2016; 54:1301-1313. [PMID: 26843107 PMCID: PMC5310569 DOI: 10.1007/s12035-016-9742-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/22/2016] [Indexed: 12/23/2022]
Abstract
The tumor necrosis factor receptor-associated factors (TRAFs) have been classically described as adaptor proteins that function as solely cytosolic signaling intermediates for the TNF receptor superfamily, Toll-like receptors (TLRs), NOD, like receptors (NLRs), cytokine receptors, and others. In this study, we show for the first time that TRAFs are present within the cytoplasm and nucleus of Neuro2a cells and primary cortical neurons, and that TRAF2 and TRAF3 translocate into the nucleus within minutes of CD40L stimulation. Analysis of the transcriptional regulatory potential of TRAFs by luciferase assay revealed that each of the TRAFs differentially functions as a transcriptional activator or repressor in a cell-specific manner. Interestingly, ChIP-qPCR data demonstrate that TRAFs 2/3, p65, and pRNAPol II form part of a transcriptional complex on the Icam-1 gene promoter upon CD40L stimulation. We further determined that TRAF2 recruitment to the nucleus is critical for the ubiquitination of H2b, a transcription permissive epigenetic modification. Our findings demonstrate for the first time that TRAFs 2/3 participate in the formation of a CD40L-induced transcriptional complex in neuronal cells.
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8
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Bankert KC, Oxley KL, Smith SM, Graham JP, de Boer M, Thewissen M, Simons PJ, Bishop GA. Induction of an Altered CD40 Signaling Complex by an Antagonistic Human Monoclonal Antibody to CD40. THE JOURNAL OF IMMUNOLOGY 2015; 194:4319-27. [DOI: 10.4049/jimmunol.1402903] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/20/2015] [Indexed: 11/19/2022]
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9
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Roles for TNF-receptor associated factor 3 (TRAF3) in lymphocyte functions. Cytokine Growth Factor Rev 2013; 25:147-56. [PMID: 24433987 DOI: 10.1016/j.cytogfr.2013.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 12/15/2013] [Indexed: 12/27/2022]
Abstract
TRAF3 is an adapter protein that serves and regulates the functions of several types of receptors, located both inside the cell and at the plasma membrane. These include members of the TNF receptor superfamily (TNFR-SF), toll-like receptors (TLR), and cytokine receptors. It has become increasingly evident that the roles and functions of TRAF3 are highly context-dependent. TRAF3 can serve distinct roles for different receptors in the same cell, and also has highly cell-type-dependent functions. This review focuses upon the current state of knowledge regarding how TRAF3 regulates the biology and effector functions of B and T lymphocytes, two major cell types of the adaptive immune response in which TRAF3 has markedly distinct roles.
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10
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Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATL), whereas the highly related HTLV-2 is not associated with ATL or other cancers. In addition to ATL leukemogenesis, studies of the HTLV viruses also provide an exceptional model for understanding basic pathogenic mechanisms of virus-host interactions and human oncogenesis. Accumulating evidence suggests that the viral regulatory protein Tax and host inflammatory transcription factor NF-κB are largely responsible for the different pathogenic potentials of HTLV-1 and HTLV-2. Here, we discuss the molecular mechanisms of HTLV-1 oncogenic pathogenesis with a focus on the interplay between the Tax oncoprotein and NF-κB pro-oncogenic signaling. We also outline some of the most intriguing and outstanding questions in the fields of HTLV and NF-κB. Answers to those questions will greatly advance our understanding of ATL leukemogenesis and other NF-κB-associated tumorigenesis and will help us design personalized cancer therapies.
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11
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Hildebrand JM, Yi Z, Buchta CM, Poovassery J, Stunz LL, Bishop GA. Roles of tumor necrosis factor receptor associated factor 3 (TRAF3) and TRAF5 in immune cell functions. Immunol Rev 2012; 244:55-74. [PMID: 22017431 DOI: 10.1111/j.1600-065x.2011.01055.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A large and diverse group of receptors utilizes the family of cytoplasmic signaling proteins known as tumor necrosis factor receptor (TNFR)-associated factors (TRAFs). In recent years, there has been a resurgence of interest and exploration of the roles played by TRAF3 and TRAF5 in cellular regulation, particularly in cells of the immune system, the cell types of focus in this review. This work has revealed that TRAF3 and TRAF5 can play diverse roles for different receptors even in the same cell type, as well as distinct roles in different cell types. Evidence indicates that TRAF3 and TRAF5 play important roles beyond the TNFR-superfamily (SF) and viral mimics of its members, mediating certain innate immune receptor and cytokine receptor signals, and most recently, signals delivered by the T-cell receptor (TCR) signaling complex. Additionally, much research has demonstrated the importance of TRAF3-mediated cellular regulation via its cytoplasmic interactions with additional signaling proteins. In particular, we discuss below evidence for the participation by TRAF3 in a number of the regulatory post-translational modifications involving ubiquitin that are important in various signaling pathways.
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Affiliation(s)
- Joanne M Hildebrand
- Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA
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12
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Ganeff C, Remouchamps C, Boutaffala L, Benezech C, Galopin G, Vandepaer S, Bouillenne F, Ormenese S, Chariot A, Schneider P, Caamaño J, Piette J, Dejardin E. Induction of the alternative NF-κB pathway by lymphotoxin αβ (LTαβ) relies on internalization of LTβ receptor. Mol Cell Biol 2011; 31:4319-34. [PMID: 21896778 PMCID: PMC3209329 DOI: 10.1128/mcb.05033-11] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 08/26/2011] [Indexed: 01/29/2023] Open
Abstract
Several tumor necrosis factor receptor (TNFR) family members activate both the classical and the alternative NF-κB pathways. However, how a single receptor engages these two distinct pathways is still poorly understood. Using lymphotoxin β receptor (LTβR) as a prototype, we showed that activation of the alternative, but not the classical, NF-κB pathway relied on internalization of the receptor. Further molecular analyses revealed a specific cytosolic region of LTβR essential for its internalization, TRAF3 recruitment, and p100 processing. Interestingly, we found that dynamin-dependent, but clathrin-independent, internalization of LTβR appeared to be required for the activation of the alternative, but not the classical, NF-κB pathway. In vivo, ligand-induced internalization of LTβR in mesenteric lymph node stromal cells correlated with induction of alternative NF-κB target genes. Thus, our data shed light on LTβR cellular trafficking as a process required for specific biological functions of NF-κB.
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Affiliation(s)
- Corinne Ganeff
- Unit of Molecular Immunology and Signal Transduction
- Laboratory of Virology and Immunology
| | - Caroline Remouchamps
- Unit of Molecular Immunology and Signal Transduction
- Laboratory of Virology and Immunology
| | - Layla Boutaffala
- Unit of Molecular Immunology and Signal Transduction
- Laboratory of Virology and Immunology
| | - Cécile Benezech
- MRC Centre for Immune Regulation, University of Birmingham, Birmingham, United Kingdom
| | - Géraldine Galopin
- Unit of Molecular Immunology and Signal Transduction
- Laboratory of Virology and Immunology
| | - Sarah Vandepaer
- Unit of Molecular Immunology and Signal Transduction
- Laboratory of Virology and Immunology
| | | | | | - Alain Chariot
- Laboratory of Medical Chemistry, GIGA-Research, University of Liège, Liège, Belgium
| | - Pascal Schneider
- Institute of Biochemistry, University of Lausanne, Lausanne, Switzerland
| | - Jorge Caamaño
- MRC Centre for Immune Regulation, University of Birmingham, Birmingham, United Kingdom
| | | | - Emmanuel Dejardin
- Unit of Molecular Immunology and Signal Transduction
- Laboratory of Virology and Immunology
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13
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Abstract
Tumor necrosis factor receptor (TNFR) superfamily members mediate the cellular response to a wide variety of biological inputs. The responses range from cell death, survival, differentiation, proliferation, to the regulation of immunity. All these physiological responses are regulated by a limited number of highly pleiotropic kinases. The fact that the same signaling molecules are involved in transducing signals from TNFR superfamily members that regulate different and even opposing processes raises the question of how their specificity is determined. Regulatory strategies that can contribute to signaling specificity include scaffolding to control kinase specificity, combinatorial use of several signal transducers, and temporal control of signaling. In this review, we discuss these strategies in the context of TNFR superfamily member signaling.
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Affiliation(s)
- Bärbel Schröfelbauer
- Signaling Systems Laboratory, Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0375, USA.
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14
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Xie P, Poovassery J, Stunz LL, Smith SM, Schultz ML, Carlin LE, Bishop GA. Enhanced Toll-like receptor (TLR) responses of TNFR-associated factor 3 (TRAF3)-deficient B lymphocytes. J Leukoc Biol 2011; 90:1149-57. [PMID: 21971520 DOI: 10.1189/jlb.0111044] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The key role of TRAF6 in TLR signaling pathways is well known. More recent evidence has implicated TRAF3 as another TRAF family member important to certain TLR responses of myeloid cells. Previous studies demonstrate that TRAF3 functions are highly context-dependent, displaying receptor and cell-type specificity. We thus examined the TLR responses of TRAF3(-/-)mouse B lymphocytes to test the hypothesis that TRAF3 plays distinct roles in such responses, depending on cell type. TRAF3(-/-) DC are known to have a defect in type 1 IFN production and here, showed diminished production of TNF and IL-10 and unaltered IL-6. In marked contrast, TRAF3(-/-) B cells made elevated amounts of TNF and IL-6 protein, as well as IL-10 and IP-10 mRNA, in response to TLR ligands. Also, in contrast to TRAF3(-/-) DC, the type 1 IFN pathway was elevated in TRAF3(-/-) B cells. Increased early responses of TRAF3(-/-) B cells to TLR signals were independent of cell survival or proliferation but associated with elevated canonical NF-κB activation. Additionally, TRAF3(-/-) B cells displayed enhanced TLR-mediated expression of AID and Ig isotype switching. Thus, TRAF3 plays varied and cell type-specific, biological roles in TLR responses.
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Affiliation(s)
- Ping Xie
- Department of Microbiology, The University of Iowa, Iowa City, Iowa, USA
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15
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Graham JP, Arcipowski KM, Bishop GA. Differential B-lymphocyte regulation by CD40 and its viral mimic, latent membrane protein 1. Immunol Rev 2010; 237:226-48. [PMID: 20727039 DOI: 10.1111/j.1600-065x.2010.00932.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
CD40 plays a vital role in humoral immunity, via its potent and multifaceted function as an activating receptor of various immune cells, most notably B lymphocytes. The Epstein-Barr virus-encoded transforming protein latent membrane protein 1 (LMP1) serves as a functional mimic of CD40 signals to B cells but lacks key regulatory controls that restrain CD40 signaling. This allows LMP1 to activate B cells in an abnormal manner that can contribute to the pathogenesis of human B-cell lymphoma and autoimmune disease. This review focuses upon a comparative analysis of CD40 versus LMP1 functions and mechanisms of action in B lymphocytes, discussing how this comparison can provide valuable information on both how CD40 signaling is normally regulated and how LMP1 disrupts the normal CD40 pathways, which can provide information of value to therapeutic design.
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Affiliation(s)
- John P Graham
- Interdisciplinary Graduate Program in Immunology, The University of Iowa, Iowa City, IA 52242, USA
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16
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Hildebrand JM, Luo Z, Manske MK, Price-Troska T, Ziesmer SC, Lin W, Hostager BS, Slager SL, Witzig TE, Ansell SM, Cerhan JR, Bishop GA, Novak AJ. A BAFF-R mutation associated with non-Hodgkin lymphoma alters TRAF recruitment and reveals new insights into BAFF-R signaling. ACTA ACUST UNITED AC 2010; 207:2569-79. [PMID: 21041452 PMCID: PMC2989778 DOI: 10.1084/jem.20100857] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The cytokine B cell activating factor (BAFF) and its receptor, BAFF receptor (BAFF-R), modulate signaling cascades critical for B cell development and survival. We identified a novel mutation in TNFRSF13C, the gene encoding human BAFF-R, that is present in both tumor and germline tissue from a subset of patients with non-Hodgkin lymphoma. This mutation encodes a His159Tyr substitution in the cytoplasmic tail of BAFF-R adjacent to the TRAF3 binding motif. Signaling through this mutant BAFF-R results in increased NF-κB1 and NF-κB2 activity and increased immunoglobulin production compared with the wild-type (WT) BAFF-R. This correlates with increased TRAF2, TRAF3, and TRAF6 recruitment to His159Tyr BAFF-R. In addition, we document a requirement for TRAF6 in WT BAFF-R signaling. Together, these data identify a novel lymphoma-associated mutation in human BAFF-R that results in NF-κB activation and reveals TRAF6 as a necessary component of normal BAFF-R signaling.
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17
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Thu YM, Richmond A. NF-κB inducing kinase: a key regulator in the immune system and in cancer. Cytokine Growth Factor Rev 2010; 21:213-26. [PMID: 20685151 PMCID: PMC2939163 DOI: 10.1016/j.cytogfr.2010.06.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Accepted: 06/28/2010] [Indexed: 12/29/2022]
Abstract
NF-κB inducing kinase (NIK) is a kinase that activates the canonical and non-canonical NF-κB pathways to control transcriptional expression of certain proteins such as cytokines, chemokines and NF-κB signaling molecules. Many advances have been made in understanding the molecular mechanisms by which the stability of NIK is regulated to affect downstream signaling. Genetic mouse models suggest that NIK plays an essential role in the regulation of the immune system as well as in the bone microenvironment. Increasing evidence links NIK to the tumorigenesis of hematological cancers, such as multiple myeloma, and solid tumors, such as pancreatic carcinoma and melanoma. Understanding the mechanism by which NIK is de-regulated will potentially provide therapeutic options for certain diseases such as autoimmunity and cancer.
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Affiliation(s)
- Yee Mon Thu
- Department of Veterans Affairs Medical Center, Department of Cancer Biology, Vanderbilt University School of Medicine, 432 PRB, 23 Avenue South at Pierce, Nashville, TN 37232, USA
| | - Ann Richmond
- Department of Veterans Affairs Medical Center, Department of Cancer Biology, Vanderbilt University School of Medicine, 432 PRB, 23 Avenue South at Pierce, Nashville, TN 37232, USA
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18
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Bista P, Zeng W, Ryan S, Bailly V, Browning JL, Lukashev ME. TRAF3 controls activation of the canonical and alternative NFkappaB by the lymphotoxin beta receptor. J Biol Chem 2010; 285:12971-8. [PMID: 20185819 PMCID: PMC2857099 DOI: 10.1074/jbc.m109.076091] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 02/25/2010] [Indexed: 11/06/2022] Open
Abstract
Components of lymphotoxin beta receptor (LTBR)-associated signaling complexes, including TRAF2, TRAF3, NIK, IKK1, and IKK2 have been shown to participate in the coupling of LTBR to NFkappaB. Here, we report that TRAF3 functions as a negative regulator of LTBR signaling via both canonical and non-canonical NFkappaB pathways by two distinct mechanisms. Analysis of NFkappaB signaling in cell lines with functionally intact NFkappaB pathway but lacking LTBR-mediated induction of NFkappaB target genes revealed an inverse association of cellular TRAF3 levels with LTBR-specific defect in canonical NFkappaB activation. Increased expression of TRAF3 correlated with its increased recruitment to LTBR-induced signaling complexes, decreased recruitment of TRAF2, and attenuated phosphorylation of IkappaB alpha and RelA. In contrast, activation of NFkappaB by TNF did not depend on TRAF3 levels. siRNA-mediated depletion of TRAF3 promoted recruitment of TRAF2 and IKK1 to activated LTBR, enabling LTBR-inducible canonical NFkappaB signaling and NFkappaB target gene expression. TRAF3 knock-down also increased mRNA and protein expression of several non-canonical NFkappaB components, including NFkappaB2/p100, RelB, and NIK, accompanied by processing of NFkappaB2/p100 into p52. These effects of TRAF3 depletion did not require LTBR signaling and were consistent with autonomous activation of the non-canonical NFkappaB pathway. Our data illustrate the function of TRAF3 as a dual-mode repressor of LTBR signaling that controls activation of canonical NFkappaB, and de-repression of the intrinsic activity of non-canonical NFkappaB. Modulation of cellular TRAF3 levels may thus contribute to regulation of NFkappaB-dependent gene expression by LTBR by affecting the balance of LTBR-dependent activation of canonical and non-canonical NFkappaB pathways.
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Affiliation(s)
| | | | | | - Veronique Bailly
- Protein Biochemistry, Biogen Idec, Inc., Cambridge, Massachusetts 02142
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19
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Ha H, Han D, Choi Y. TRAF-mediated TNFR-family signaling. CURRENT PROTOCOLS IN IMMUNOLOGY 2009; Chapter 11:11.9D.1-11.9D.19. [PMID: 19918944 DOI: 10.1002/0471142735.im1109ds87] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The tumor necrosis factor (TNF) superfamily consists of a wide variety of cell-bound and secreted proteins that regulate numerous cellular processes. In particular, TNF-family proteins regulate the proliferation and death of tumor cells, as well as activated immune cells. This overview discusses the mammalian TNF receptor-associated factors (TRAFs), of which TRAF1, 2, 3, 5, and 6 have been shown to interact directly or indirectly with members of the TNF receptor superfamily. Structural features of TRAF proteins are described along with a discussion of TRAF-interacting proteins and the signaling pathways activated by the TRAF proteins. Finally, we examine the phenotypes observed in TRAF-knockout mice.
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Affiliation(s)
- Hyunil Ha
- University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Daehee Han
- University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Yongwon Choi
- University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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20
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Graham JP, Moore CR, Bishop GA. Roles of the TRAF2/3 binding site in differential B cell signaling by CD40 and its viral oncogenic mimic, LMP1. THE JOURNAL OF IMMUNOLOGY 2009; 183:2966-73. [PMID: 19667091 DOI: 10.4049/jimmunol.0900442] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The EBV protein, latent membrane protein 1 (LMP1), is a functional mimic of the cellular receptor CD40, but signals to B lymphocytes in an amplified and sustained manner compared with CD40. LMP1 contributes to the development of B cell lymphoma in immunosuppressed patients, and may exacerbate flares of certain autoimmune diseases. The cytoplasmic domain of LMP1 binds the signaling adaptor TRAF2 with lower avidity than the cytoplasmic domain of CD40, and TRAF2 is needed for CD40-mediated degradation of TRAFs 2 and 3. LMP1 doesn't induce TRAF degradation, and employs TRAF3 as a positive mediator of cell signaling, whereas CD40 signals are inhibited by TRAF3. We thus tested the hypothesis that relative affinity for TRAF2, and/or distinct sequence differences in the TRAF2/3 binding sites of CD40 vs LMP1, controls the disparate ways in which CD40 and LMP1 use TRAFs 2 and 3, and their distinct signaling characteristics. CD40 and LMP1 mutants in which the TRAF binding site sequences were swapped were examined, testing TRAF binding and degradation, and induction of B cell activation. Results revealed that TRAF binding affinity and TRAF binding site sequence dictate a distinct subset of CD40 vs LMP1 signaling properties. Examination of TRAF binding, degradation, cytokine production, IgM secretion, and the activation of c-Jun kinase and NF-kappaB revealed that some events are dictated by TRAF binding site sequences, others are partially regulated, and still others are independent of the TRAF binding site sequence.
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Affiliation(s)
- John P Graham
- Interdisciplinary Program in Immunology, Veterans Affairs Medical Center, Iowa City, Iowa 52242, USA
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21
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Gudi R, Barkinge J, Hawkins S, Prabhakar B, Kanteti P. Siva-1 promotes K-48 polyubiquitination of TRAF2 and inhibits TCR-mediated activation of NF-kappaB. J Environ Pathol Toxicol Oncol 2009; 28:25-38. [PMID: 19392652 DOI: 10.1615/jenvironpatholtoxicoloncol.v28.i1.30] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The proapoptotic protein Siva-1 plays an important role in some of the extrinsic and intrinsic apoptosis signaling pathways in cancer cells. Previously, we showed that Siva-1 inhibited the activity of the prosurvival transcription factor NF-kappaB. In the present study, upon TCR cross-linking of Jurkat T leukemia cells, we demonstrated that the inhibitory target of Siva-1 is upstream of the IKK complex in the NF-kappaB signaling pathway. Additionally, Siva-1 also suppressed the activity of another crucial transcription factor AP-1, and a common mediator of both these pathways is the adaptor protein TRAF2. Further, we observed that Siva-1 indeed interacted with TRAF2 and negatively regulated its activity by promoting K48-hnked polyubiquitination. Siva-1 specifically interacted with the ring finger domain of TRAF2, which is essential for its E3 hgase activity and its ability to subsequently activate NF-kappaB. TCR cross-linking of Jurkat T cells that lacked Siva-1 revealed significantly lowered K48- but elevated K63-ubiquitinated TRAF2 levels upon TCR cross-linking, suggesting that the differential pattern of ubiquitination in these cells essentially contributed to a robust and sustained activation of NF-kappaB. The above results demonstrated an important role for endogenous Siva-1 in negatively regulating NF-kappaB activation by targeting TRAF2.
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Affiliation(s)
- Radhika Gudi
- Department of Microbiology and Immunology, University of Illinois, Chicago, IL 60612, USA
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22
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Zarnegar BJ, Wang Y, Mahoney DJ, Dempsey PW, Cheung HH, He J, Shiba T, Yang X, Yeh WC, Mak TW, Korneluk RG, Cheng G. Noncanonical NF-kappaB activation requires coordinated assembly of a regulatory complex of the adaptors cIAP1, cIAP2, TRAF2 and TRAF3 and the kinase NIK. Nat Immunol 2008; 9:1371-8. [PMID: 18997794 PMCID: PMC2676931 DOI: 10.1038/ni.1676] [Citation(s) in RCA: 504] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 10/10/2008] [Indexed: 02/07/2023]
Abstract
Recent studies suggest that nuclear factor kappaB-inducing kinase (NIK) is suppressed through constitutive proteasome-mediated degradation regulated by TRAF2, TRAF3 and cIAP1 or cIAP2. Here we demonstrated that the degradation of NIK occurs upon assembly of a regulatory complex through TRAF3 recruitment of NIK and TRAF2 recruitment of cIAP1 and cIAP2. In contrast to TRAF2 and TRAF3, cIAP1 and cIAP2 seem to play redundant roles in the degradation of NIK, as inhibition of both cIAPs was required for noncanonical NF-kappaB activation and increased survival and proliferation of primary B lymphocytes. Furthermore, the lethality of TRAF3 deficiency in mice could be rescued by a single NIK gene, highlighting the importance of tightly regulated NIK.
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Affiliation(s)
- Brian J Zarnegar
- Department of Microbiology, Immunology & Molecular Genetics, University of California Los Angeles, 609 Charles E. Young Drive East, Los Angeles, California 90095, USA
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23
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cIAP1-dependent TRAF2 degradation regulates the differentiation of monocytes into macrophages and their response to CD40 ligand. Blood 2008; 113:175-85. [PMID: 18827186 DOI: 10.1182/blood-2008-02-137919] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Peripheral blood monocytes are plastic cells that migrate to tissues and differentiate into various cell types, including macrophages, dendritic cells, and osteoclasts. We have described the migration of cellular inhibitor of apoptosis protein 1 (cIAP1), a member of the IAP family of proteins, from the nucleus to the Golgi apparatus in monocytes undergoing differentiation into macrophages. Here we show that, once in the cytoplasm, cIAP1 is involved in the degradation of the adaptor protein tumor necrosis factor receptor-associated factor 2 (TRAF2) by the proteosomal machinery. Inhibition of cIAP1 prevents the decrease in TRAF2 expression that characterizes macrophage formation. We demonstrate that TRAF2 is initially required for macrophage differentiation as its silencing prevents Ikappa-Balpha degradation, nuclear factor-kappaB (NF-kappaB) p65 nuclear translocation, and the differentiation process. Then, we show that cIAP1-mediated degradation of TRAF2 allows the differentiation process to progress. This degradation is required for the macrophages to be fully functional as TRAF2 overexpression in differentiated cells decreases the c-Jun N-terminal kinase-mediated synthesis and the secretion of proinflammatory cytokines, such as interleukin-8 and monocyte chemoattractant protein 1 (MCP-1) in response to CD40 ligand. We conclude that TRAF2 expression and subsequent degradation are required for the differentiation of monocytes into fully functional macrophages.
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24
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Sun SC, Ley SC. New insights into NF-kappaB regulation and function. Trends Immunol 2008; 29:469-78. [PMID: 18775672 DOI: 10.1016/j.it.2008.07.003] [Citation(s) in RCA: 232] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/03/2008] [Accepted: 07/04/2008] [Indexed: 01/24/2023]
Abstract
NF-kappaB (nuclear factor-kappaB) transcription factors have multiple critical roles in the regulation of immune responses. In unstimulated cells, NF-kappaB proteins are sequestered in the cytoplasm by IkappaB inhibitory proteins. Various immune stimuli induce the IkappaB kinase (IKK) to phosphorylate IkappaBs, triggering their ubiquitination and proteasomal degradation, which permits nuclear translocation of associated NF-kappaB subunits and activation of NF-kappaB target genes. Recent studies have highlighted the importance of dynamic ubiquitination-deubiquitination events in regulating this canonical NF-kappaB signaling pathway. Ubiquitination additionally plays critical roles in activation of the noncanonical pathway that regulates NF-kappaB via signal-induced processing of NF-kappaB2 p100. New research has also identified several novel regulatory proteins that control the transcriptional activity of nuclear NF-kappaB.
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Affiliation(s)
- Shao-Cong Sun
- Department of Immunology, MD Anderson Cancer Center, University of Texas, Houston, TX 77030, USA.
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25
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Abstract
Tumor necrosis factor receptor associated factors (TRAFs) play a variety of interesting and important roles in the regulation of B lymphocyte function. They act both as cytoplasmic regulatory molecules, and as signal transducers for receptors involved in both innate and adaptive humoral immune responses. In this brief review, we highlight the current state of knowledge of the diverse roles of TRAF molecules in the functions of B lymphocytes.
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Affiliation(s)
- Ping Xie
- Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA
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26
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Tucker TA, Schwiebert LM. CD40 ligation decreases its protein half-life at the cell surface. Eur J Immunol 2008; 38:864-9. [PMID: 18253927 DOI: 10.1002/eji.200737828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
CD40 is expressed on a variety of tumors; anti-CD40 agonists promote tumor cell apoptosis and subsequent tumor regression. Because the effectiveness of anti-CD40- agonists is dependent upon CD40 surface expression, the current study examined ligation-mediated changes in CD40 protein half-life (t(1/2))( )at the cell surface. This study utilized a CD40(+) epithelial cell line (9HTEo-), a CD40 null epithelial cell line (HT-29) engineered to express either wild-type (WT) or mutant (T254A, Q263A, E235A, Delta201) CD40, and the anti-CD40 antibody G28.5. Ligation of endogenous CD40 expressed on 9HTEo- cells decreased CD40 surface protein t(1/2 )from 13 to 4 h (p <0.05). Ligation of WT-, Q263A-, or T254A-CD40 expressed on engineered HT-29 cells decreased CD40 surface protein t(1/2) from an average of 8 to 4 h (p <0.05); T254A and Q263A contain mutated TNF receptor-associated factor (TRAF)2/3-binding sites. In contrast, ligation of E235A and Delta201-CD40 had no affect on its surface protein t(1/2) (p <0.05); E235A contains a mutated TRAF6-binding site while Delta201 lacks an intact cytoplasmic tail. These results suggest that anti-CD40 agonists decrease CD40 surface protein t(1/2) via a mechanism that involves TRAF6 but not TRAF2/3. The therapeutic implications for CD40-mediated tumor regression are discussed.
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Affiliation(s)
- Torry A Tucker
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL 35294-0005, USA
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27
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Vanden Bush TJ, Bishop GA. TLR7 and CD40 cooperate in IL-6 production via enhanced JNK and AP-1 activation. Eur J Immunol 2008; 38:400-9. [PMID: 18228247 DOI: 10.1002/eji.200737602] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During vaccination or infection, adaptive and innate immune receptors of B cells are engaged by microbial antigens/ligands. A better understanding of how innate and adaptive signaling pathways interact could enlighten B lymphocyte biology as well as aid immunotherapy strategies and vaccine design. To address this goal, we examined the effects of TLR stimulation on BCR and CD40-induced B cell activation. Synergistic production of IL-6 was observed in both human and mouse primary B cells stimulated through B cell antigen receptors, CD40 and TLR7, and these two receptors also cooperated independently of BCR signals. The enhanced IL-6 production was dependent upon the activity of c-Jun kinase (JNK) and cFos. Dual stimulation through CD40 and TLR7 markedly enhanced JNK activity. The increased level of active JNK in dual-stimulated cells was accompanied by an increase in the level of active AP-1 monomers cJun and cFos. The stimulation of B cells through both CD40 and TLR7 therefore enhanced the production of cytokines through increased JNK signaling and AP-1 activity. In addition, the dual stimulation increased cFos/AP-1 species in stimulated cells, effectively expanding the repertoire of AP-1 dimers as compared to singly stimulated B cells.
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Affiliation(s)
- Tony J Vanden Bush
- Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA
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28
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Bishop GA, Moore CR, Xie P, Stunz LL, Kraus ZJ. TRAF proteins in CD40 signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 597:131-51. [PMID: 17633023 DOI: 10.1007/978-0-387-70630-6_11] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The tumor necrosis factor receptor (TNFR) superfamily molecule CD40 is expressed by a wide variety of cell types following activation signals, and constitutively on B lymphocytes, macrophages, and dendritic cells. CD40 signals to cells stimulate kinase activation, gene expression, production of a antibody and a variety of cytokines, expression or upregulation of surface molecules, and protection or promotion of apoptosis. Initial steps in CD40-mediated signal cascades involve the interactions of CD40 with various members of the TNFR-associated factor (TRAF) family of cytoplasmic proteins. This review summarizes current understanding of the nature of these interactions, and how they induce and regulate CD40 functions.
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Affiliation(s)
- Gail A Bishop
- Department of Microbiology, Interdisciplinary Graduate Program in Immunology, University of Iowa and the Iowa City VAMC, Iowa City, Iowa 52242, USA.
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29
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Qiao G, Lei M, Li Z, Sun Y, Minto A, Fu YX, Ying H, Quigg RJ, Zhang J. Negative regulation of CD40-mediated B cell responses by E3 ubiquitin ligase Casitas-B-lineage lymphoma protein-B. THE JOURNAL OF IMMUNOLOGY 2007; 179:4473-9. [PMID: 17878343 DOI: 10.4049/jimmunol.179.7.4473] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It has been documented that CD40 is essential for B cell function. Casitas-B-lineage lymphoma protein-b (Cbl-b), an adapter protein and ubiquitin ligase, has been shown to regulate the activation of T and B cells through their Ag receptors. In this study, we report that CD40-induced B cell proliferation is significantly augmented in mice lacking Cbl-b. Furthermore, Cbl-b(-/-) mice display enhanced thymus-dependent Ab responses and germinal center formation, whereas introduction of CD40 deficiency abolishes these effects. Hyper thymus-dependent humoral response in Cbl-b(-/-) mice is in part due to an intrinsic defect in B cells. Mechanistically, Cbl-b selectively down-modulates CD40-induced activation of NF-kappaB and JNK. Cbl-b associates with TNF receptor-associated factor 2 upon CD40 ligation, and inhibits the recruitment of TNF receptor-associated factor 2 to the CD40. Together, our data suggest that Cbl-b attenuates CD40-mediated NF-kappaB and JNK activation, thereby suppressing B cell responses.
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Affiliation(s)
- Guilin Qiao
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL 6063, USA
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30
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Liu J, Yoshida Y, Yamashita U. Suppressive effect of reactive oxygen species on CD40-induced B cell activation. FEBS Lett 2007; 581:5043-9. [PMID: 17919601 DOI: 10.1016/j.febslet.2007.09.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Accepted: 09/20/2007] [Indexed: 01/02/2023]
Abstract
Reactive oxygen species (ROS) produced by the innate immune system work as effectors to destroy pathogens and to control cellular responses. However, their role in the adaptive immune response remains unclear. Here we studied the effect of exogenous ROS on CD40-induced B cell activation. H2O2 treatment inhibited CD40-induced immunoglobulin production of B cells, DNA binding of NF-kappaB, IkappaBalpha degradation and IKK phosphorylation. On the other hand, H2O2 treatment did not induce obvious B cell death after 30 min of stimulation. Although the ligation of anti-CD40 antibody was not disturbed by H2O2, TRAF2 recruitment to CD40 was inhibited. These results suggest that exogenous ROS play a negative role in CD40 signaling during B cell activation.
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Affiliation(s)
- Jiqin Liu
- Department of Immunology, School of Medicine, University of Occupational and Environmental Health, Kitakyusyu 807-8555, Japan
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31
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Rowland SL, Tremblay MM, Ellison JM, Stunz LL, Bishop GA, Hostager BS. A Novel Mechanism for TNFR-Associated Factor 6-Dependent CD40 Signaling. THE JOURNAL OF IMMUNOLOGY 2007; 179:4645-53. [PMID: 17878362 DOI: 10.4049/jimmunol.179.7.4645] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Members of the TNFR family play critical roles in the regulation of the immune system. One member of the family critical for efficient activation of T-dependent humoral immune responses is CD40, a cell surface protein expressed by B cells and other APC. The cytoplasmic domain of CD40 interacts with several members of the TNFR-associated factor (TRAF) family, which link CD40 to intracellular signaling pathways. TRAF2 and 6 appear to play particularly important roles in CD40 signaling. Previous studies suggest that the two molecules have certain overlapping roles in signaling, but that unique roles for each molecule also exist. To better define the roles of TRAF2 and TRAF6 in CD40 signaling, we used somatic cell gene targeting to generate TRAF-deficient mouse B cell lines. A20.2J cells deficient in TRAF6 exhibit marked defects in CD40-mediated JNK activation and the up-regulation of CD80. Our previous experiments with TRAF2-deficient B cell lines suggest that TRAF6 and TRAF2 may have redundant roles in CD40-mediated NF-kappaB activation. Consistent with this hypothesis, we found CD40-mediated activation of NF-kappaB intact in TRAF6-deficient cells and defective in cells lacking both TRAF2 and TRAF6. Interestingly, we found that TRAF6 mutants defective in CD40 binding were able to restore CD40-mediated JNK activation and CD80 up-regulation in TRAF6-deficient cells, indicating that TRAF6 may be able to contribute to certain CD40 signals without directly binding CD40.
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Affiliation(s)
- Sarah L Rowland
- Integrated Department of Immunology, National Jewish Medical and Research Center, Denver, CO 80262, USA
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32
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Multiple roles of TRAF3 signaling in lymphocyte function. Immunol Res 2007; 39:22-32. [DOI: 10.1007/s12026-007-0068-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 01/30/2023]
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33
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Thieu VT, Nguyen ET, McCarthy BP, Bruns HA, Kapur R, Chang CH, Kaplan MH. IL-4-stimulated NF-kappaB activity is required for Stat6 DNA binding. J Leukoc Biol 2007; 82:370-9. [PMID: 17513694 DOI: 10.1189/jlb.1106707] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
IL-4 is a critical cytokine in the regulation of immune responses. In B lymphocytes, IL-4 signaling promotes the Stat6-dependent cell surface expression of several proteins including MHC Class II and CD86. However, the requirement for other transcription factors in IL-4-induced B cell gene expression has not been studied extensively. Here, we show that IL-4 induces NF-kappaB p100 processing to NF-kappaB p52 in B cells but not in T cells or macrophages. IL-4 induced NF-kappaB p52 production requires PI-3K activity and correlates with IkappaB kinase phosphorylation and TNF receptor-associated factor 3 degradation. Blocking NF-kappaB activity eliminates IL-4-stimulated gene expression in B cells by reducing IL-4-induced DNA binding but not phosphorylation or nuclear localization of Stat6. These results describe a novel role for NF-kappaB in IL-4-induced signaling and gene expression.
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Affiliation(s)
- Vivian T Thieu
- Department of Microbiology and Immunology, Indiana University School of Medicine, and Walther Cancer Institute, Indianapolis, Indiana, USA
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34
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Lu LF, Ahonen CL, Lind EF, Raman VS, Cook WJ, Lin LL, Noelle RJ. The in vivo function of a noncanonical TRAF2-binding domain in the C-terminus of CD40 in driving B-cell growth and differentiation. Blood 2007; 110:193-200. [PMID: 17360936 PMCID: PMC1896113 DOI: 10.1182/blood-2006-07-038414] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recruitment of tumor necrosis factor receptor-associated factors (TRAFs) 1, 2, 3, 5, and 6 to the CD40 cytoplasmic tail upon CD40 trimerization results in downstream signaling events that ultimately lead to CD40-dependent, thymus-dependent (TD) humoral immune responses. Previously, we have shown signaling through the C-terminal tail of CD40 in the absence of canonical TRAF-binding sites is capable of signaling through an alternative TRAF2-binding site. Here, we demonstrate that B cells from mice harboring CD40 with only the C-terminal tail can activate both canonical and noncanonical NFkappaB signaling pathways. Moreover, while lacking germinal center formation, several hallmarks of humoral immune responses including clonal B-cell activation/expansion, antibody isotype switching, and affinity maturation remain normal. This study demonstrates a new functional domain in CD40 that controls critical aspects of B-cell immunity in an in vivo setting.
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Affiliation(s)
- Li-Fan Lu
- Department of Microbiology and Immunology, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH 03756, USA
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35
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Abstract
CD40 plays a significant role in the pathogenesis of inflammation and autoimmunity. B cell CD40 directly activates cells, which can result in autoantibody production. T cells can also express CD40, with an increased frequency and amount of expression seen in CD4(+) T lymphocytes of autoimmune mice, including T cells from mice with collagen-induced arthritis. However, the mechanisms of T cell CD40 function have not been clearly defined. To test the hypothesis that CD40 can serve as a costimulatory molecule on T lymphocytes, CD40(+) T cells from collagen-induced arthritis mice were examined in parallel with mouse and human T cell lines transfected with CD40. CD40 served as effectively as CD28 in costimulating TCR-mediated activation, including induction of kinase and transcription factor activities and production of cytokines. An additional enhancement was seen when both CD40 and CD28 signals were combined with AgR stimulation. These findings reveal potent biologic functions for T cell CD40 and suggest an additional means for amplification of autoimmune responses.
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Affiliation(s)
- Melissa E Munroe
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
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36
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Abstract
B cells maintain homeostasis by balancing cell viability and cell death. B lymphocytes are susceptible to mitochondria- and receptor-initiated cell death at various stages of peripheral differentiation and during immune responses. The inducible transcription factor NF-kappaB enhances cell viability by activating genes that counteract both cell-death pathways. This review uses characteristic features of NF-kappaB activation and downregulation to provide insight into the regulation of B cell apoptosis in the periphery. In particular, the temporal patterns of NF-kappaB induction, differences between Rel family members, and the intersection between canonical and noncanonical signaling pathways in keeping B cells alive are discussed.
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Affiliation(s)
- Ranjan Sen
- Laboratory of Cellular and Molecular Biology, National Institute on Aging, Baltimore, Maryland 21224, USA.
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37
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Xie P, Hostager BS, Munroe ME, Moore CR, Bishop GA. Cooperation between TNF Receptor-Associated Factors 1 and 2 in CD40 Signaling. THE JOURNAL OF IMMUNOLOGY 2006; 176:5388-400. [PMID: 16622006 DOI: 10.4049/jimmunol.176.9.5388] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
TNFR-associated factor 1 (TRAF1) is unique among the TRAF family, lacking most zinc-binding features, and showing marked up-regulation following activation signals. However, the biological roles that TRAF1 plays in immune cell signaling have been elusive, with many reports assigning contradictory roles to TRAF1. The overlapping binding site for TRAFs 1, 2, and 3 on many TNFR superfamily molecules, together with the early lethality of mice deficient in TRAFs 2 and 3, has complicated the quest for a clear understanding of the functions of TRAF1. Using a new method for gene targeting by homologous recombination in somatic cells, we produced and studied signaling by CD40 and its viral oncogenic mimic, latent membrane protein 1 (LMP1) in mouse B cell lines lacking TRAF1, TRAF2, or both TRAFs. Results indicate that TRAFs 1 and 2 cooperate in CD40-mediated activation of the B cell lines, with a dual deficiency leading to a markedly greater loss of function than that of either TRAF alone. In the absence of TRAF1, an increased amount of TRAF2 was recruited to lipid rafts, and subsequently, more robust degradation of TRAF2 and TRAF3 was induced in response to CD40 signaling. In contrast, LMP1 did not require either TRAFs 1 or 2 to induce activation. Taken together, our findings indicate that TRAF1 and TRAF2 cooperate in CD40 but not LMP1 signaling and suggest that cellular levels of TRAF1 may play an important role in modulating the degradation of TRAF2 and TRAF3 in response to signals from the TNFR superfamily.
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Affiliation(s)
- Ping Xie
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
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