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Ybarra TK, Bishop GA. TRAF3 regulation of proximal TLR signaling in B cells. J Leukoc Biol 2024; 116:210-223. [PMID: 38489541 PMCID: PMC11271984 DOI: 10.1093/jleuko/qiae038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/24/2024] [Accepted: 02/09/2024] [Indexed: 03/17/2024] Open
Abstract
Toll-like receptors are pattern recognition receptors that bridge the innate and adaptive immune responses and are critical for host defense. Most studies of Toll-like receptors have focused upon their roles in myeloid cells. B lymphocytes express most Toll-like receptors and are responsive to Toll-like receptor ligands, yet Toll-like receptor-mediated signaling in B cells is relatively understudied. This is an important knowledge gap, as Toll-like receptor functions can be cell type specific. In striking contrast to myeloid cells, TRAF3 inhibits TLR-mediated functions in B cells. TRAF3-deficient B cells display enhanced IRF3 and NFκB activation, cytokine production, immunoglobulin isotype switching, and antibody production in response to Toll-like receptors 3, 4, 7, and 9. Here, we address the question of how TRAF3 impacts initial B-cell Toll-like receptor signals to regulate downstream activation. We found that TRAF3 in B cells associated with proximal Toll-like receptor 4 and 7 signaling proteins, including MyD88, TRAF6, and the tyrosine kinase Syk. In the absence of TRAF3, TRAF6 showed a greater association with several Toll-like receptor signaling proteins, suggesting that TRAF3 may inhibit TRAF6 access to Toll-like receptor signaling complexes and thus early Toll-like receptor signaling. In addition, our results highlight a key role for Syk in Toll-like receptor signaling in B cells. In the absence of TRAF3, Syk activation was enhanced in response to ligands for Toll-like receptors 4 and 7, and Syk inhibition reduced downstream Toll-like receptor-mediated NFκB activation and proinflammatory cytokine production. This study reveals multiple mechanisms by which TRAF3 serves as a key negative regulator of early Toll-like receptor signaling events in B cells.
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Affiliation(s)
- Tiffany K Ybarra
- Interdisciplinary Graduate Program in Immunology, University of Iowa, 285 Newton Road, Iowa City, IA 52242, United States
- Departments of Microbiology and Immunology, University of Iowa, 285 Newton Road, Iowa City, IA 52242, United States
| | - Gail A Bishop
- Interdisciplinary Graduate Program in Immunology, University of Iowa, 285 Newton Road, Iowa City, IA 52242, United States
- Departments of Microbiology and Immunology, University of Iowa, 285 Newton Road, Iowa City, IA 52242, United States
- VA Medical Center, University of Iowa, 285 Newton Road, Iowa City, IA 52242, United States
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2
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Vashisht M, Ge H, John J, McKelvey HA, Chen J, Chen Z, Wang JH. TRAF2/3 deficient B cells resist DNA damage-induced apoptosis via NF-κB2/XIAP/cIAP2 axis and IAP antagonist sensitizes mutant lymphomas to chemotherapeutic drugs. Cell Death Dis 2023; 14:599. [PMID: 37679334 PMCID: PMC10485046 DOI: 10.1038/s41419-023-06122-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 08/22/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023]
Abstract
Deletion of TRAF2 or TRAF3 in B cells prolongs their survival. However, it remains unknown whether deletion of such factors affects B cells' ability to tolerate DNA damage, which can be induced by chemotherapeutics and cause apoptosis. Genetic alterations of TRAF2 or TRAF3 are observed in subsets of human B-cell lymphomas and B cell-specific deletion of TRAF3 led to lymphoma development in aged mice. However, it remains unknown whether double deficiency of TRAF2 and TRAF3 accelerates B-cell lymphomagenesis. Here, we showed that B cell-specific TRAF2/3 double deficient (B-TRAF2/3-DKO) B cells were remarkably more resistant to DNA damage-induced apoptosis via upregulating cIAP2 and XIAP, which in turn attenuates caspase-3 activation. Mechanistically, resistance to DNA damage-induced apoptosis required NF-κB2, which effects by upregulating XIAP and cIAP2 transcription. B-TRAF2/3-DKO mice exhibited a shorter lifespan and succumbed to splenomegaly and lymphadenopathy. Unexpectedly, the incidence of B-cell lymphoma development in B-TRAF2/3-DKO mice was relatively rare (∼10%). Sequencing B cell receptor repertoire of diseased B cells revealed that TRAF2/3 deficiency caused abnormal oligoclonal or clonal expansion of B cells. While a fraction of mutant B cells (25-43%) from aged diseased mice harbored recurrent chromosomal translocations, primary B cells isolated from young B-TRAF2/3-DKO mice had no detectable chromosomal alterations, suggesting that TRAF2/3 deficiency per se does not cause evident genomic instability in B cells. Chemo-resistant TRAF3-deficient B-cell lymphomas were sensitized to chemotherapeutic drugs by blocking IAP activity using IAP antagonist. We conclude that double deficiency of TRAF2 and TRAF3 does not accelerate B-cell lymphomagenesis. Our studies provide insight into mechanisms regulating DNA damage-induced apoptosis and may help develop effective therapies targeting mutant B-cell lymphomas using IAP antagonist.
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Affiliation(s)
- Monika Vashisht
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Huaibin Ge
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Jessy John
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Harlie A McKelvey
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Jingxin Chen
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Zhangguo Chen
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
| | - Jing H Wang
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
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3
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Siegmund D, Wagner J, Wajant H. TNF Receptor Associated Factor 2 (TRAF2) Signaling in Cancer. Cancers (Basel) 2022; 14:cancers14164055. [PMID: 36011046 PMCID: PMC9406534 DOI: 10.3390/cancers14164055] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/05/2022] [Accepted: 08/19/2022] [Indexed: 12/19/2022] Open
Abstract
Simple Summary Tumor necrosis factor (TNF) receptor associated factor-2 (TRAF2) is an intracellular adapter protein with E3 ligase activity, which interacts with a plethora of other signaling proteins, including plasma membrane receptors, kinases, phosphatases, other E3 ligases, and deubiquitinases. TRAF2 is involved in various cancer-relevant cellular processes, such as the activation of transcription factors of the NFκB family, stimulation of mitogen-activated protein (MAP) kinase cascades, endoplasmic reticulum (ER) stress signaling, autophagy, and the control of cell death programs. In a context-dependent manner, TRAF2 promotes tumor development but it can also act as a tumor suppressor. Based on a general description, how TRAF2 in concert with TRAF2-interacting proteins and other TRAF proteins act at the molecular level is discussed for its importance for tumor development and its potential usefulness as a therapeutic target in cancer therapy. Abstract Tumor necrosis factor (TNF) receptor associated factor-2 (TRAF2) has been originally identified as a protein interacting with TNF receptor 2 (TNFR2) but also binds to several other receptors of the TNF receptor superfamily (TNFRSF). TRAF2, often in concert with other members of the TRAF protein family, is involved in the activation of the classical NFκB pathway and the stimulation of various mitogen-activated protein (MAP) kinase cascades by TNFRSF receptors (TNFRs), but is also required to inhibit the alternative NFκB pathway. TRAF2 has also been implicated in endoplasmic reticulum (ER) stress signaling, the regulation of autophagy, and the control of cell death programs. TRAF2 fulfills its functions by acting as a scaffold, bringing together the E3 ligase cellular inhibitor of apoptosis-1 (cIAP1) and cIAP2 with their substrates and various regulatory proteins, e.g., deubiquitinases. Furthermore, TRAF2 can act as an E3 ligase by help of its N-terminal really interesting new gene (RING) domain. The finding that TRAF2 (but also several other members of the TRAF family) interacts with the latent membrane protein 1 (LMP1) oncogene of the Epstein–Barr virus (EBV) indicated early on that TRAF2 could play a role in the oncogenesis of B-cell malignancies and EBV-associated non-keratinizing nasopharyngeal carcinoma (NPC). TRAF2 can also act as an oncogene in solid tumors, e.g., in colon cancer by promoting Wnt/β-catenin signaling. Moreover, tumor cell-expressed TRAF2 has been identified as a major factor-limiting cancer cell killing by cytotoxic T-cells after immune checkpoint blockade. However, TRAF2 can also be context-dependent as a tumor suppressor, presumably by virtue of its inhibitory effect on the alternative NFκB pathway. For example, inactivating mutations of TRAF2 have been associated with tumor development, e.g., in multiple myeloma and mantle cell lymphoma. In this review, we summarize the various TRAF2-related signaling pathways and their relevance for the oncogenic and tumor suppressive activities of TRAF2. Particularly, we discuss currently emerging concepts to target TRAF2 for therapeutic purposes.
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Verstegen NJM, Ubels V, Westerhoff HV, van Ham SM, Barberis M. System-Level Scenarios for the Elucidation of T Cell-Mediated Germinal Center B Cell Differentiation. Front Immunol 2021; 12:734282. [PMID: 34616402 PMCID: PMC8488341 DOI: 10.3389/fimmu.2021.734282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/02/2021] [Indexed: 12/12/2022] Open
Abstract
Germinal center (GC) reactions are vital to the correct functioning of the adaptive immune system, through formation of high affinity, class switched antibodies. GCs are transient anatomical structures in secondary lymphoid organs where specific B cells, after recognition of antigen and with T cell help, undergo class switching. Subsequently, B cells cycle between zones of proliferation and somatic hypermutation and zones where renewed antigen acquisition and T cell help allows for selection of high affinity B cells (affinity maturation). Eventually GC B cells first differentiate into long-lived memory B cells (MBC) and finally into plasma cells (PC) that partially migrate to the bone marrow to encapsulate into long-lived survival niches. The regulation of GC reactions is a highly dynamically coordinated process that occurs between various cells and molecules that change in their signals. Here, we present a system-level perspective of T cell-mediated GC B cell differentiation, presenting and discussing the experimental and computational efforts on the regulation of the GCs. We aim to integrate Systems Biology with B cell biology, to advance elucidation of the regulation of high-affinity, class switched antibody formation, thus to shed light on the delicate functioning of the adaptive immune system. Specifically, we: i) review experimental findings of internal and external factors driving various GC dynamics, such as GC initiation, maturation and GCBC fate determination; ii) draw comparisons between experimental observations and mathematical modeling investigations; and iii) discuss and reflect on current strategies of modeling efforts, to elucidate B cell behavior during the GC tract. Finally, perspectives are specifically given on to the areas where a Systems Biology approach may be useful to predict novel GCBC-T cell interaction dynamics.
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Affiliation(s)
- Niels J M Verstegen
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Synthetic Systems Biology and Nuclear Organization, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Victor Ubels
- Systems Biology, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Centre for Mathematical and Computational Biology, CMCB, University of Surrey, Guildford, United Kingdom
| | - Hans V Westerhoff
- Synthetic Systems Biology and Nuclear Organization, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands.,Department of Molecular Cell Physiology, VU University Amsterdam, Amsterdam, Netherlands
| | - S Marieke van Ham
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Synthetic Systems Biology and Nuclear Organization, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Matteo Barberis
- Synthetic Systems Biology and Nuclear Organization, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands.,Systems Biology, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Centre for Mathematical and Computational Biology, CMCB, University of Surrey, Guildford, United Kingdom
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5
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Chen Z, Wang JH. How the Signaling Crosstalk of B Cell Receptor (BCR) and Co-Receptors Regulates Antibody Class Switch Recombination: A New Perspective of Checkpoints of BCR Signaling. Front Immunol 2021; 12:663443. [PMID: 33841447 PMCID: PMC8027318 DOI: 10.3389/fimmu.2021.663443] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/11/2021] [Indexed: 11/21/2022] Open
Abstract
Mature B cells express B cell antigen receptor (BCR), toll-like receptors (TLR) and TNF family receptors including CD40 and B-cell activating factor receptor (BAFFR). These receptors transduce cellular signals to govern the physiological and pathological processes in B cells including B cell development and differentiation, survival, proliferation, and antibody-mediated immune responses as well as autoimmune diseases and B cell lymphomagenesis. Effective antibody-mediated immune responses require class switch recombination (CSR), a somatic DNA recombination event occurring at the immunoglobulin heavy chain (Igh) gene locus. Mature B cells initially express IgM as their BCR, and CSR enables the B cells to switch from expressing IgM to expressing different classes of antibodies including IgG, IgA or IgE that exhibit distinct effector functions. Here, we briefly review recent findings about how the signaling crosstalk of the BCR with TLRs, CD40 and BAFFR regulates CSR, antibody-mediate immune responses, and B cell anergy.
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Affiliation(s)
- Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado, Aurora, CO, United States
| | - Jing H Wang
- Department of Medicine, Division of Hematology and Oncology, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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Whillock AL, Ybarra TK, Bishop GA. TNF receptor-associated factor 3 restrains B-cell receptor signaling in normal and malignant B cells. J Biol Chem 2021; 296:100465. [PMID: 33639170 PMCID: PMC8042179 DOI: 10.1016/j.jbc.2021.100465] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/20/2022] Open
Abstract
TRAF3 has diverse signaling functions, which vary by cell type. Uniquely in B lymphocytes, TRAF3 inhibits homeostatic survival. Highlighting the role of TRAF3 as a tumor suppressor, loss-of-function TRAF3 mutations are associated with human B-cell malignancies, while B-cell-specific deletion of TRAF3 in mice leads to autoimmunity and lymphoma development. The role of TRAF3 in inhibiting noncanonical NF-κB activation, CD40 and BAFF-R signaling to B cells is well documented. In contrast, TRAF3 enhances many T-cell effector functions, through associating with and enhancing signaling by the T-cell receptor (TCR)-CD28 complex. The present study was designed to determine the role of TRAF3 in signaling via the B-cell antigen receptor (BCR). The BCR is crucial for antigen recognition, survival, proliferation, and antibody production, and defects in BCR signaling can promote abnormal survival of malignant B cells. Here, we show that TRAF3 is associated with both CD79B and the BCR-activated kinases Syk and Btk following BCR stimulation. BCR-induced phosphorylation of Syk and additional downstream kinases was increased in TRAF3−/− B cells, with regulation observed in both follicular and marginal zone B-cell subsets. BCR stimulation of TRAF3−/− B cells resulted in increased surface expression of MHC-II, CD80, and CD86 molecules. Interestingly, increased survival of TRAF3−/− primary B cells was resistant to inhibition of Btk, while TRAF3-deficient malignant B-cell lines showed enhanced sensitivity. TRAF3 serves to restrain normal and malignant BCR signaling, with important implications for its role in normal B-cell biology and abnormal survival of malignant B cells.
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Affiliation(s)
- Amy L Whillock
- Department of Microbiology & Immunology, University of Iowa, Iowa City, Iowa, USA; Immunology Graduate Program, University of Iowa, Iowa City, Iowa, USA; Medical Scientist Training Program, University of Iowa, Iowa City, Iowa, USA; Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | - Tiffany K Ybarra
- Department of Microbiology & Immunology, University of Iowa, Iowa City, Iowa, USA; Immunology Graduate Program, University of Iowa, Iowa City, Iowa, USA
| | - Gail A Bishop
- Department of Microbiology & Immunology, University of Iowa, Iowa City, Iowa, USA; Immunology Graduate Program, University of Iowa, Iowa City, Iowa, USA; Medical Scientist Training Program, University of Iowa, Iowa City, Iowa, USA; Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA; Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA; VA Medical Center, Iowa City, Iowa, USA.
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7
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Munroe ME, Anderson JR, Gross TF, Stunz LL, Bishop GA, James JA. Epstein-Barr Functional Mimicry: Pathogenicity of Oncogenic Latent Membrane Protein-1 in Systemic Lupus Erythematosus and Autoimmunity. Front Immunol 2021; 11:606936. [PMID: 33613527 PMCID: PMC7886997 DOI: 10.3389/fimmu.2020.606936] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 12/21/2020] [Indexed: 11/16/2022] Open
Abstract
Systemic lupus erythematosus (SLE) and other autoimmune diseases are propelled by immune dysregulation and pathogenic, disease-specific autoantibodies. Autoimmunity against the lupus autoantigen Sm is associated with cross-reactivity to Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1). Additionally, EBV latent membrane protein-1 (LMP1), initially noted for its oncogenic activity, is an aberrantly active functional mimic of the B cell co-stimulatory molecule CD40. Mice expressing a transgene (Tg) for the mCD40-LMP1 hybrid molecule (containing the cytoplasmic tail of LMP1) have mild autoantibody production and other features of immune dysregulation by 2-3 months of age, but no overt autoimmune disease. This study evaluates whether exposure to the EBV molecular mimic, EBNA-1, stimulates antigen-specific and concurrently-reactive humoral and cellular immunity, as well as lupus-like features. After immunization with EBNA-1, mCD40-LMP1 Tg mice exhibited enhanced, antigen-specific, cellular and humoral responses compared to immunized WT congenic mice. EBNA-1 specific proliferative and inflammatory cytokine responses, including IL-17 and IFN-γ, were significantly increased (p<0.0001) in mCD40-LMP1 Tg mice, as well as antibody responses to amino- and carboxy-domains of EBNA-1. Of particular interest was the ability of mCD40-LMP1 to drive EBNA-1 associated molecular mimicry with the lupus-associated autoantigen, Sm. EBNA-1 immunized mCD40-LMP1 Tg mice exhibited enhanced proliferative and cytokine cellular responses (p<0.0001) to the EBNA-1 homologous epitope PPPGRRP and the Sm B/B' cross-reactive sequence PPPGMRPP. When immunized with the SLE autoantigen Sm, mCD40-LMP1 Tg mice again exhibited enhanced cellular and humoral immune responses to both Sm and EBNA-1. Cellular immune dysregulation with EBNA-1 immunization in mCD40-LMP1 Tg mice was accompanied by enhanced splenomegaly, increased serum blood urea nitrogen (BUN) and creatinine levels, and elevated anti-dsDNA and antinuclear antibody (ANA) levels (p<0.0001 compared to mCD40 WT mice). However, no evidence of immune-complex glomerulonephritis pathology was noted, suggesting that a combination of EBV and genetic factors may be required to drive lupus-associated renal disease. These data support that the expression of LMP1 in the context of EBNA-1 may interact to increase immune dysregulation that leads to pathogenic, autoantigen-specific lupus inflammation.
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Affiliation(s)
- Melissa E. Munroe
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Jourdan R. Anderson
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Timothy F. Gross
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Laura L. Stunz
- Department of Microbiology & Immunology, The University of Iowa, Iowa City, IA, United States
| | - Gail A. Bishop
- Department of Microbiology & Immunology, The University of Iowa, Iowa City, IA, United States
- Department of Internal Medicine, The University of Iowa, Iowa City, IA, United States
- Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA, United States
- Iowa City VA Medical Center, Iowa City, IA, United States
| | - Judith A. James
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
- Department of Medicine and Pathology, Oklahoma University Health Sciences Center, Oklahoma City, OK, United States
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Rayego-Mateos S, Morgado-Pascual JL, Valdivielso JM, Sanz AB, Bosch-Panadero E, Rodrigues-Díez RR, Egido J, Ortiz A, González-Parra E, Ruiz-Ortega M. TRAF3 Modulation: Novel Mechanism for the Anti-inflammatory Effects of the Vitamin D Receptor Agonist Paricalcitol in Renal Disease. J Am Soc Nephrol 2020; 31:2026-2042. [PMID: 32631974 DOI: 10.1681/asn.2019111206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 04/07/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND CKD leads to vitamin D deficiency. Treatment with vitamin D receptor agonists (VDRAs) may have nephroprotective and anti-inflammatory actions, but their mechanisms of action are poorly understood. METHODS Modulation of the noncanonical NF-κB2 pathway and its component TNF receptor-associated factor 3 (TRAF3) by the VDRA paricalcitol was studied in PBMCs from patients with ESKD, cytokine-stimulated cells, and preclinical kidney injury models. RESULTS In PBMCs isolated from patients with ESKD, TRAF3 protein levels were lower than in healthy controls. This finding was associated with evidence of noncanonical NF-κB2 activation and a proinflammatory state. However, PBMCs from patients with ESKD treated with paricalcitol did not exhibit these features. Experiments in cultured cells confirmed the link between TRAF3 and NF-κB2/inflammation. Decreased TRAF3 ubiquitination in K48-linked chains and cIAP1-TRAF3 interaction mediated the mechanisms of paricalcitol action.TRAF3 overexpression by CRISPR/Cas9 technology mimicked VDRA's effects. In a preclinical model of kidney injury, paricalcitol inhibited renal NF-κB2 activation and decreased renal inflammation. In VDR knockout mice with renal injury, paricalcitol prevented TRAF3 downregulation and NF-κB2-dependent gene upregulation, suggesting a VDR-independent anti-inflammatory effect of paricalcitol. CONCLUSIONS These data suggest the anti-inflammatory actions of paricalcitol depend on TRAF3 modulation and subsequent inhibition of the noncanonical NF-κB2 pathway, identifying a novel mechanism for VDRA's effects. Circulating TRAF3 levels could be a biomarker of renal damage associated with the inflammatory state.
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Affiliation(s)
- Sandra Rayego-Mateos
- Molecular and Cellular Biology in Renal and Vascular Pathology, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz,Universidad autonoma de madrid, Madrid, Spain.,Vascular and Renal Translational Research Group. Institut de Receca Biomedica de Lleida (IRBLleida), Lleida, Spain
| | - Jose Luis Morgado-Pascual
- Molecular and Cellular Biology in Renal and Vascular Pathology, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz,Universidad autonoma de madrid, Madrid, Spain.,REDinREN (Red de Investigación Renal), Madrid, Spain
| | - José Manuel Valdivielso
- Vascular and Renal Translational Research Group. Institut de Receca Biomedica de Lleida (IRBLleida), Lleida, Spain.,REDinREN (Red de Investigación Renal), Madrid, Spain
| | - Ana Belén Sanz
- REDinREN (Red de Investigación Renal), Madrid, Spain.,Laboratory of Nephrology and Hypertension, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz-Universidad Autónoma Madrid, 28040 Madrid, Spain
| | - Enrique Bosch-Panadero
- Laboratory of Nephrology and Hypertension, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz-Universidad Autónoma Madrid, 28040 Madrid, Spain
| | - Raúl R Rodrigues-Díez
- Molecular and Cellular Biology in Renal and Vascular Pathology, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz,Universidad autonoma de madrid, Madrid, Spain
| | - Jesús Egido
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundación Jiménez Díaz.Universidad Autónoma. 28040 Madrid, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM). 28029 Madrid, Spain
| | - Alberto Ortiz
- REDinREN (Red de Investigación Renal), Madrid, Spain.,Laboratory of Nephrology and Hypertension, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz-Universidad Autónoma Madrid, 28040 Madrid, Spain
| | - Emilio González-Parra
- Laboratory of Nephrology and Hypertension, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz-Universidad Autónoma Madrid, 28040 Madrid, Spain
| | - Marta Ruiz-Ortega
- Molecular and Cellular Biology in Renal and Vascular Pathology, Fundación Instituto de Investigación Sanitaria-Fundación Jiménez Díaz,Universidad autonoma de madrid, Madrid, Spain .,REDinREN (Red de Investigación Renal), Madrid, Spain
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9
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Chen Z, Krinsky A, Woolaver RA, Wang X, Chen SMY, Popolizio V, Xie P, Wang JH. TRAF3 Acts as a Checkpoint of B Cell Receptor Signaling to Control Antibody Class Switch Recombination and Anergy. THE JOURNAL OF IMMUNOLOGY 2020; 205:830-841. [PMID: 32591397 DOI: 10.4049/jimmunol.2000322] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023]
Abstract
The BCR recognizes foreign Ags to initiate humoral immunity that needs isotype-switched Abs generated via class switch recombination (CSR); however, stimulating the BCR in the absence of costimulation (e.g., CD40) does not induce CSR; thus, it remains elusive whether and how the BCR induces CSR mechanistically. Autoreactive B cells can maintain anergy via unresponsiveness of their BCRs to self-antigens. However, it remains unknown what molecule(s) restrict BCR signaling strength for licensing BCR-induced CSR and whether deficiency of such molecule(s) disrupts autoreactive B cell anergy and causes B cell-mediated diseases by modulating BCR signaling. In this study, we employ mouse models to show that the BCR's capacity to induce CSR is restrained by B cell-intrinsic checkpoints TRAF3 and TRAF2, whose deletion in B cells enables the BCR to induce CSR in the absence of costimulation. TRAF3 deficiency permits BCR-induced CSR by elevating BCR-proximal signaling intensity. Furthermore, NF-κB2 is required for BCR-induced CSR in TRAF3-deficient B cells but not for CD40-induced or LPS-induced CSR, suggesting that TRAF3 restricts NF-κB2 activation to specifically limit the BCR's ability to induce CSR. TRAF3 deficiency also disrupts autoreactive B cell anergy by elevating calcium influx in response to BCR stimulation, leading to lymphoid organ disorders and autoimmune manifestations. We showed that TRAF3 deficiency-associated autoimmune phenotypes can be rectified by limiting BCR repertoires or attenuating BCR signaling strength. Thus, our studies highlight the importance of TRAF3-mediated restraint on BCR signaling strength for controlling CSR, B cell homeostasis, and B cell-mediated disorders.
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Affiliation(s)
- Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045;
| | - Alexandra Krinsky
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Rachel A Woolaver
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Xiaoguang Wang
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Samantha M Y Chen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Vince Popolizio
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Ping Xie
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854; and.,Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901
| | - Jing H Wang
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045;
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10
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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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11
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A central role of IKK2 and TPL2 in JNK activation and viral B-cell transformation. Nat Commun 2020; 11:685. [PMID: 32019925 PMCID: PMC7000802 DOI: 10.1038/s41467-020-14502-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 12/10/2019] [Indexed: 12/13/2022] Open
Abstract
IκB kinase 2 (IKK2) is well known for its pivotal role as a mediator of the canonical NF-κB pathway, which has important functions in inflammation and immunity, but also in cancer. Here we identify a novel and critical function of IKK2 and its co-factor NEMO in the activation of oncogenic c-Jun N-terminal kinase (JNK) signaling, induced by the latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV). Independent of its kinase activity, the TGFβ-activated kinase 1 (TAK1) mediates LMP1 signaling complex formation, NEMO ubiquitination and subsequent IKK2 activation. The tumor progression locus 2 (TPL2) kinase is induced by LMP1 via IKK2 and transmits JNK activation signals downstream of IKK2. The IKK2-TPL2-JNK axis is specific for LMP1 and differs from TNFα, Interleukin-1 and CD40 signaling. This pathway mediates essential LMP1 survival signals in EBV-transformed human B cells and post-transplant lymphoma, and thus qualifies as a target for treatment of EBV-induced cancer.
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12
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Argiriadi MA, Benatuil L, Dubrovska I, Egan DA, Gao L, Greischar A, Hardman J, Harlan J, Iyer RB, Judge RA, Lake M, Perron DC, Sadhukhan R, Sielaff B, Sousa S, Wang R, McRae BL. CD40/anti-CD40 antibody complexes which illustrate agonist and antagonist structural switches. BMC Mol Cell Biol 2019; 20:29. [PMID: 31382872 PMCID: PMC6683420 DOI: 10.1186/s12860-019-0213-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/17/2019] [Indexed: 01/20/2023] Open
Abstract
Background CD40 is a 48 kDa type I transmembrane protein that is constitutively expressed on hematopoietic cells such as dendritic cells, macrophages, and B cells. Engagement of CD40 by CD40L expressed on T cells results in the production of proinflammatory cytokines, induces T helper cell function, and promotes macrophage activation. The involvement of CD40 in chronic immune activation has resulted in CD40 being proposed as a therapeutic target for a range of chronic inflammatory diseases. CD40 antagonists are currently being explored for the treatment of autoimmune diseases and several anti-CD40 agonist mAbs have entered clinical development for oncological indications. Results To better understand the mode of action of anti-CD40 mAbs, we have determined the x-ray crystal structures of the ABBV-323 (anti-CD40 antagonist, ravagalimab) Fab alone, ABBV-323 Fab complexed to human CD40 and FAB516 (anti-CD40 agonist) complexed to human CD40. These three crystals structures 1) identify the conformational CD40 epitope for ABBV-323 recognition 2) illustrate conformational changes which occur in the CDRs of ABBV-323 Fab upon CD40 binding and 3) develop a structural hypothesis for an agonist/antagonist switch in the LCDR1 of this proprietary class of CD40 antibodies. Conclusions The structure of ABBV-323 Fab demonstrates a unique method for antagonism by stabilizing the proposed functional antiparallel dimer for CD40 receptor via novel contacts to LCDR1, namely residue position R32 which is further supported by a closely related agonist antibody FAB516 which shows only monomeric recognition and no contacts with LCDR1 due to a mutation to L32 on LCDR1. These data provide a structural basis for the full antagonist activity of ABBV-323. Electronic supplementary material The online version of this article (10.1186/s12860-019-0213-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maria A Argiriadi
- AbbVie Bioresearch Center, 381 Plantation Street, Worcester, MA, 01605, USA.
| | - Lorenzo Benatuil
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | | | - David A Egan
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Lei Gao
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Amy Greischar
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Jennifer Hardman
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - John Harlan
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Ramesh B Iyer
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Russell A Judge
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Marc Lake
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Denise C Perron
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | | | - Bernhard Sielaff
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Silvino Sousa
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Rui Wang
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Bradford L McRae
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
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13
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Abstract
Class switch recombination (CSR) generates isotype-switched antibodies with distinct effector functions essential for mediating effective humoral immunity. CSR is catalyzed by activation-induced deaminase (AID) that initiates DNA lesions in the evolutionarily conserved switch (S) regions at the immunoglobulin heavy chain (Igh) locus. AID-initiated DNA lesions are subsequently converted into DNA double stranded breaks (DSBs) in the S regions of Igh locus, repaired by non-homologous end-joining to effect CSR in mammalian B lymphocytes. While molecular mechanisms of CSR are well characterized, it remains less well understood how upstream signaling pathways regulate AID expression and CSR. B lymphocytes express multiple receptors including the B cell antigen receptor (BCR) and co-receptors (e.g., CD40). These receptors may share common signaling pathways or may use distinct signaling elements to regulate CSR. Here, we discuss how signals emanating from different receptors positively or negatively regulate AID expression and CSR.
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Affiliation(s)
- Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
| | - Jing H Wang
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
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14
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Woolaver RA, Wang X, Dollin Y, Xie P, Wang JH, Chen Z. TRAF2 Deficiency in B Cells Impairs CD40-Induced Isotype Switching That Can Be Rescued by Restoring NF-κB1 Activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2018; 201:3421-3430. [PMID: 30341187 PMCID: PMC6246814 DOI: 10.4049/jimmunol.1800337] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 09/20/2018] [Indexed: 12/22/2022]
Abstract
Effective humoral immunity requires class switch recombination (CSR) catalyzed by activation-induced cytidine deaminase (AID). In response to T cell-dependent (TD) Ags, CSR can be induced by CD40 signaling in B cells. TNFR-associated factors 2 and 3 (TRAF2/TRAF3) function as adaptors of the CD40 signaling pathway. B cell-intrinsic TRAF2 or TRAF3 (B-TRAF2 or B-TRAF3) knockout mice were previously reported to have indistinguishable phenotypes in gene expression, B cell survival and development, and enlarged peripheral lymphoid organs. However, it remains unknown whether deficiency of B-TRAF2 or B-TRAF3 differentially affects TD humoral immune responses and CD40-induced CSR. In this article, we show that B-TRAF2 is essential for optimal isotype switching induced by in vivo TD Ag immunization or by engaging CD40 in vitro. Our data clarify the controversial role of B-TRAF3 and confirm its dispensability in CD40-induced CSR. Mechanistically, CD40-induced AID expression was markedly impaired by B-TRAF2, but not B-TRAF3, deficiency. Moreover, B-TRAF2 deficiency causes defective activation of the NF-κB1 complex in a CD40-autonomous manner, and restoring CD40-induced NF-κB1 activation in TRAF2-deficient B cells rescues AID expression and CSR. We conclude that TRAF2 is essential but TRAF3 is dispensable for TD humoral immunity and CD40-induced CSR. Our studies provide significant biological bases for optimizing treatment of B cell-associated immune disorders by targeting CD40 signaling.
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Affiliation(s)
- Rachel A Woolaver
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Xiaoguang Wang
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Yonatan Dollin
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Ping Xie
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854; and
- Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901
| | - Jing H Wang
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045;
| | - Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045;
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15
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Bishop GA, Stunz LL, Hostager BS. TRAF3 as a Multifaceted Regulator of B Lymphocyte Survival and Activation. Front Immunol 2018; 9:2161. [PMID: 30319624 PMCID: PMC6165887 DOI: 10.3389/fimmu.2018.02161] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/03/2018] [Indexed: 12/20/2022] Open
Abstract
The adaptor protein TNF receptor-associated factor 3 (TRAF3) serves as a powerful negative regulator in multiple aspects of B cell biology. Early in vitro studies in transformed cell lines suggested the potential of TRAF3 to inhibit signaling by its first identified binding receptor, CD40. However, because the canonical TRAF3 binding site on many receptors also mediates binding of other TRAFs, and whole-mouse TRAF3 deficiency is neonatally lethal, an accurate understanding of TRAF3's specific functions was delayed until conditional TRAF3-deficient mice were produced. Studies of B cell-specific TRAF3-deficient mice, complemented by investigations in normal and malignant mouse and human B cells, reveal that TRAF3 has powerful regulatory roles that are unique to this TRAF, as well as functions context-specific to the B cell. This review summarizes the current state of knowledge of these roles and functions. These include inhibition of signaling by plasma membrane receptors, negative regulation of intracellular receptors, and restraint of cytoplasmic NF- κB pathways. TRAF3 is also now known to function as a resident nuclear protein, and to impact B cell metabolism. Through these and additional mechanisms TRAF3 exerts powerful restraint upon B cell survival and activation. It is thus perhaps not surprising that TRAF3 has been revealed as an important tumor suppressor in B cells. The many and varied functions of TRAF3 in B cells, and new directions to pursue in future studies, are summarized and discussed here.
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Affiliation(s)
- Gail A. Bishop
- Department of Microbiology & Immunology, University of Iowa, Iowa City, IA, United States
- Department of Internal Medicine, University of Iowa, Iowa City, IA, United States
- Iowa City VA Health Care System, Iowa City, Iowa City, IA, United States
| | - Laura L. Stunz
- Department of Microbiology & Immunology, University of Iowa, Iowa City, IA, United States
| | - Bruce S. Hostager
- Department of Microbiology & Immunology, University of Iowa, Iowa City, IA, United States
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16
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Rothschild DE, McDaniel DK, Ringel-Scaia VM, Allen IC. Modulating inflammation through the negative regulation of NF-κB signaling. J Leukoc Biol 2018; 103:10.1002/JLB.3MIR0817-346RRR. [PMID: 29389019 PMCID: PMC6135699 DOI: 10.1002/jlb.3mir0817-346rrr] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 12/16/2022] Open
Abstract
Immune system activation is essential to thwart the invasion of pathogens and respond appropriately to tissue damage. However, uncontrolled inflammation can result in extensive collateral damage underlying a diverse range of auto-inflammatory, hyper-inflammatory, and neoplastic diseases. The NF-κB signaling pathway lies at the heart of the immune system and functions as a master regulator of gene transcription. Thus, this signaling cascade is heavily targeted by mechanisms designed to attenuate overzealous inflammation and promote resolution. Mechanisms associated with the negative regulation of NF-κB signaling are currently under intense investigation and have yet to be fully elucidated. Here, we provide an overview of mechanisms that negatively regulate NF-κB signaling through either attenuation of signal transduction, inhibition of posttranscriptional signaling, or interference with posttranslational modifications of key pathway components. While the regulators discussed for each group are far from comprehensive, they exemplify common mechanistic approaches that inhibit this critical biochemical signaling cascade. Despite their diversity, a commonality among these regulators is their selection of specific targets at key inflection points in the pathway, such as TNF-receptor-associated factor family members or essential kinases. A better understanding of these negative regulatory mechanisms will be essential to gain greater insight related to the maintenance of immune system homeostasis and inflammation resolution. These processes are vital elements of disease pathology and have important implications for targeted therapeutic strategies.
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Affiliation(s)
- Daniel E. Rothschild
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg VA 24061
| | - Dylan K. McDaniel
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg VA 24061
| | - Veronica M. Ringel-Scaia
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA 24061
| | - Irving C. Allen
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg VA 24061
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA 24061
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA 24016
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17
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The oncogenic membrane protein LMP1 sequesters TRAF3 in B-cell lymphoma cells to produce functional TRAF3 deficiency. Blood Adv 2017; 1:2712-2723. [PMID: 29296923 DOI: 10.1182/bloodadvances.2017009670] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 11/16/2017] [Indexed: 12/15/2022] Open
Abstract
Loss-of-function mutations in genes encoding the signaling protein tumor necrosis factor receptor-associated factor 3 (TRAF3) are commonly found in human B-cell malignancies, especially multiple myeloma and B-cell lymphoma (BCL). B-cell TRAF3 deficiency results in enhanced cell survival, elevated activation receptor signaling, and increased activity of certain transcriptional pathways regulating expression of prosurvival proteins. A recent analysis of TRAF3 protein staining of ∼300 human BCL tissue samples revealed that a higher proportion of samples expressing the oncogenic Epstein-Barr virus-encoded protein latent membrane protein 1 (LMP1) showed low/negative TRAF3 staining than predicted. LMP1, a dysregulated mimic of the CD40 receptor, binds TRAF3 more effectively than CD40. We hypothesized that LMP1 may sequester TRAF3, reducing its availability to inhibit prosurvival signaling pathways in the B cell. This hypothesis was addressed via 2 complementary approaches: (1) comparison of TRAF3-regulated activation and survival-related events with relative LMP1 expression in human BCL lines and (2) analysis of the impact upon such events in matched pairs of mouse BCL lines, both parental cells and subclones transfected with inducible LMP1, either wild-type LMP1 or a mutant LMP1 with defective TRAF3 binding. Results from both approaches showed that LMP1-expressing B cells display a phenotype highly similar to that of B cells lacking TRAF3 genes, indicating that LMP1 can render B cells functionally TRAF3 deficient without TRAF3 gene mutations, a finding of significant relevance to selecting pathway-targeted therapies for B-cell malignancies.
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18
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Wallis AM, Wallace EC, Hostager BS, Yi Z, Houtman JCD, Bishop GA. TRAF3 enhances TCR signaling by regulating the inhibitors Csk and PTPN22. Sci Rep 2017; 7:2081. [PMID: 28522807 PMCID: PMC5437045 DOI: 10.1038/s41598-017-02280-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 04/12/2017] [Indexed: 12/18/2022] Open
Abstract
The adaptor protein TNF receptor associated factor (TRAF) 3 is required for effective TCR signaling and normal T cell effector functions, and associates with the CD3/CD28 complex upon activation. To determine how TRAF3 promotes proximal TCR signaling, we studied TRAF3-deficient mouse and human T cells, which showed a marked reduction in activating phosphorylation of the TCR-associated kinase Lck. The impact of TRAF3 on this very early signaling event led to the hypothesis that TRAF3 restrains one or both of two known inhibitors of Lck, C-terminal Src kinase (Csk) and protein tyrosine phosphatase N22 (PTPN22). TRAF3 associated with Csk, promoting the dissociation of Csk from the plasma membrane. TRAF3 also associated with and regulated the TCR/CD28 induced localization of PTPN22. Loss of TRAF3 resulted in increased amounts of both Csk and PTPN22 in T cell membrane fractions and decreased association of PTPN22 with Csk. These findings identify a new role for T cell TRAF3 in promoting T cell activation, by regulating localization and functions of early TCR signaling inhibitors.
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Affiliation(s)
| | | | | | - Zuoan Yi
- Depts of Microbiology, Iowa City, IA, 52242, USA
| | - Jon C D Houtman
- Graduate Program in Immunology, Iowa City, IA, 52242, USA.,Depts of Microbiology, Iowa City, IA, 52242, USA.,Internal Medicine, Iowa City, IA, 52242, USA
| | - Gail A Bishop
- Graduate Program in Immunology, Iowa City, IA, 52242, USA. .,Biomedical Engineering, Iowa City, IA, 52242, USA. .,Depts of Microbiology, Iowa City, IA, 52242, USA. .,Internal Medicine, Iowa City, IA, 52242, USA. .,The University of Iowa and VAMC, Iowa City, IA, 52242, USA.
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19
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Lin B, Xu D, Leaman DW. X-linked inhibitor of apoptosis-associated factor 1 regulates TNF receptor 1 complex stability. FEBS Lett 2016; 590:4381-4392. [PMID: 27768232 DOI: 10.1002/1873-3468.12467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/17/2016] [Accepted: 08/30/2016] [Indexed: 11/06/2022]
Abstract
X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is a cytokine-regulated, tumor necrosis factor (TNF) receptor-associated factor (TRAF) domain-containing protein that has a poorly defined cellular function. Here, we show that ectopically expressed XAF1 inhibits TNF-ɑ-induced NF-κB activation, whereas shRNA silencing of endogenous XAF1 augments it. Our data suggest that XAF1 may inhibit TNF-ɑ-induced NF-κB activation by disrupting the assembly of the TRADD/TRAF2/RIP1 complex (complex I) downstream of TNF receptor activation. XAF1 interacts with TRAF2 and inhibits TRAF2-dependent NF-κB activation, in part, by blocking TRAF2 polyubiquitination. Our findings also indicate that although XAF1 does not directly inhibit RIP1-dependent NF-κB activation, it binds RIP1 and disrupts RIP1/TRADD association. Our data suggest that XAF1 acts as a feedback regulator of the TNF receptor signaling pathway to suppress NF-κB activation.
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Affiliation(s)
- Boren Lin
- Department of Biological Sciences, The University of Toledo, OH, USA
| | - Da Xu
- Department of Biological Sciences, The University of Toledo, OH, USA
| | - Douglas W Leaman
- Department of Biological Sciences, The University of Toledo, OH, USA
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20
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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 PMCID: PMC6608063 DOI: 10.1189/jlb.2mr0216-063r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/31/2016] [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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21
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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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22
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Etemadi N, Chopin M, Anderton H, Tanzer MC, Rickard JA, Abeysekera W, Hall C, Spall SK, Wang B, Xiong Y, Hla T, Pitson SM, Bonder CS, Wong WWL, Ernst M, Smyth GK, Vaux DL, Nutt SL, Nachbur U, Silke J. TRAF2 regulates TNF and NF-κB signalling to suppress apoptosis and skin inflammation independently of Sphingosine kinase 1. eLife 2015; 4. [PMID: 26701909 PMCID: PMC4769158 DOI: 10.7554/elife.10592] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 12/21/2015] [Indexed: 02/01/2023] Open
Abstract
TRAF2 is a component of TNF superfamily signalling complexes and plays an essential role in the regulation and homeostasis of immune cells. TRAF2 deficient mice die around birth, therefore its role in adult tissues is not well-explored. Furthermore, the role of the TRAF2 RING is controversial. It has been claimed that the atypical TRAF2 RING cannot function as a ubiquitin E3 ligase but counterclaimed that TRAF2 RING requires a co-factor, sphingosine-1-phosphate, that is generated by the enzyme sphingosine kinase 1, to function as an E3 ligase. Keratinocyte-specific deletion of Traf2, but not Sphk1 deficiency, disrupted TNF mediated NF-κB and MAP kinase signalling and caused epidermal hyperplasia and psoriatic skin inflammation. This inflammation was driven by TNF, cell death, non-canonical NF-κB and the adaptive immune system, and might therefore represent a clinically relevant model of psoriasis. TRAF2 therefore has essential tissue specific functions that do not overlap with those of Sphk1. DOI:http://dx.doi.org/10.7554/eLife.10592.001 Psoriasis is an inflammatory disorder that causes red, flaky patches of skin. The disease affects around 2% of the world’s population, and is most common in people of northern European descent. TNF is one of the key proteins in the development of psoriasis and drugs that inhibit TNF have been very successful in the treatment of this disease. However, these drugs are expensive and for unknown reasons at least 10% of patients do not respond to them. Attempts to develop better drugs for psoriasis would be assisted by an improved understanding of this disease in terms of the genes and proteins involved. Etemadi et al. set out to obtain a more detailed molecular understanding of this disease by developing new mouse models of the condition. Mice were genetically engineered such that a key gene was deleted specifically from the skin cells that form the main barrier to the environment. These mice demonstrated that defects in skin cells called keratinocytes, rather than defects in the immune response, could lead to a psoriasis-like disease. Etemadi et al. also showed that the skin cells with this genetic defect die in the presence of TNF and this cell death in mice caused a rapidly-appearing form of psoriasis. However, in the absence of TNF the mice still developed psoriasis, albeit more slowly. In this case, the condition was due to an excessive activation of a protein called NF-κB, which is known to play a role in maintaining balance in the immune system and in psoriasis. These findings reveal how keratinocytes, cell death and inflammation can directly contribute to psoriasis-like conditions in mice. The next challenge will be to determine whether these findings can be used to help patients with this condition. DOI:http://dx.doi.org/10.7554/eLife.10592.002
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Affiliation(s)
- Nima Etemadi
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia.,Olivia Newton-John Cancer Research Institute, Heidelberg, Australia.,School of Cancer Medicine, La Trobe University, Heidelberg, Australia
| | - Michael Chopin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Holly Anderton
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Maria C Tanzer
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - James A Rickard
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Waruni Abeysekera
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Cathrine Hall
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Sukhdeep K Spall
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Bing Wang
- Center for Cardiovascular Research and Education in Therapeutics, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
| | - Yuquan Xiong
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, United States
| | - Timothy Hla
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, United States
| | - Stuart M Pitson
- Centre for Cancer Biology, SA Pathology, Adelaide, Australia
| | | | - Wendy Wei-Lynn Wong
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Matthias Ernst
- Olivia Newton-John Cancer Research Institute, Heidelberg, Australia.,School of Cancer Medicine, La Trobe University, Heidelberg, Australia
| | - Gordon K Smyth
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Mathematics and Statistics, University of Melbourne, Parkville, Australia
| | - David L Vaux
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Stephen L Nutt
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Ueli Nachbur
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - John Silke
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
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23
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Albarbar B, Dunnill C, Georgopoulos NT. Regulation of cell fate by lymphotoxin (LT) receptor signalling: Functional differences and similarities of the LT system to other TNF superfamily (TNFSF) members. Cytokine Growth Factor Rev 2015; 26:659-71. [DOI: 10.1016/j.cytogfr.2015.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 05/10/2015] [Accepted: 05/13/2015] [Indexed: 12/11/2022]
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24
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Yang XD, Sun SC. Targeting signaling factors for degradation, an emerging mechanism for TRAF functions. Immunol Rev 2015; 266:56-71. [PMID: 26085207 PMCID: PMC4473799 DOI: 10.1111/imr.12311] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Tumor necrosis factor receptor (TNFR)-associated factors (TRAFs) form a family of proteins that are best known as signaling adapters of TNFRs. However, emerging evidence suggests that TRAF proteins, particularly TRAF2 and TRAF3, also regulate signal transduction by controlling the fate of intracellular signaling factors. A well-recognized function of TRAF2 and TRAF3 in this aspect is to mediate ubiquitin-dependent degradation of nuclear factor-κB (NF-κB)-inducing kinase (NIK), an action required for the control of NIK-regulated non-canonical NF-κB signaling pathway. TRAF2 and TRAF3 form a complex with the E3 ubiquitin ligase cIAP (cIAP1 or cIAP2), in which TRAF3 serves as the NIK-binding adapter. Recent evidence suggests that the cIAP-TRAF2-TRAF3 E3 complex also targets additional signaling factors for ubiquitin-dependent degradation, thereby regulating important aspects of immune and inflammatory responses. This review provides both historical aspects and new insights into the signaling functions of this ubiquitination system.
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Affiliation(s)
- Xiao-Dong Yang
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shao-Cong Sun
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, USA
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25
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Ontiveros EP, Halwani A, Stunz LL, Kamberos N, Olivier AK, Janz S, Bishop GA. A new model of LMP1-MYC interaction in B cell lymphoma. Leuk Lymphoma 2014; 55:2917-23. [PMID: 24605938 DOI: 10.3109/10428194.2014.900762] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Epstein-Barr virus (EBV) is associated with aggressive B cell lymphomas (BCLs). Latent membrane protein 1 (LMP1) of EBV is an oncogenic protein required for EBV B cell transformation. However, LMP1 is a weak oncogene in mice. Mice expressing Myc inserted 5' of the Eμ enhancer (iMyc(Eμ)), mimicking the t(8;14) translocation of endemic Burkitt lymphoma, develop delayed onset BCLs. To investigate potential cooperation between LMP1 and oncogenic MYC, we produced mice expressing the LMP1 signaling domain via a hybrid CD40-LMP1 transgene (mCD40-LMP1), and the dysregulated MYC protein of aggressive EBV+ BCLs. mCD40-LMP1/iMyc(Eμ) mice trended toward earlier BCL onset. BCLs from mCD40-LMP1/iMyc(Eμ) mice expressed LMP1 and were transplantable into immunocompetent recipients. iMyc(Eμ) and mCD40-LMP1/iMyc(Eμ) mice developed BCLs with similar immunophenotypes. LMP1 signaling was intact in BCLs as shown by inducible interleukin-6. Additionally, LMP1 signaling to tumor cells induced the two isoforms of Pim1, a constitutively active prosurvival kinase implicated in lymphomagenesis.
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26
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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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27
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Bishop GA. The many faces of TRAF molecules in immune regulation. THE JOURNAL OF IMMUNOLOGY 2013; 191:3483-5. [PMID: 24058190 DOI: 10.4049/jimmunol.1390048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Gail A Bishop
- Department of Microbiology, University of Iowa, Iowa City, IA 52242
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28
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Miliara S, Gkouskou KK, Sharp TV, Eliopoulos AG. SUMOylation is required for optimal TRAF3 signaling capacity. PLoS One 2013; 8:e80470. [PMID: 24260396 PMCID: PMC3832365 DOI: 10.1371/journal.pone.0080470] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 10/03/2013] [Indexed: 12/15/2022] Open
Abstract
TNF receptor-associated factors (TRAFs) are multifunctional adaptor proteins involved in temporal and spatial coordination of signals necessary for normal immune function. Here, we report that TRAF3, a TRAF family member with a key role in Toll-like and TNF family receptor signaling and suppressor of lymphomagenesis, is post-translationally modified by the small ubiquitin-related modifier (SUMO). Through yeast two-hybrid and co-immunoprecipitation assays we have identified Ubc9, the SUMO conjugating enzyme, as a novel TRAF3-interacting protein. We show that Ubc9-dependent SUMOylation of TRAF3 modulates optimal association with the CD40 receptor, thereby influencing TRAF3 degradation and non-canonical NF-κB activation upon CD40 triggering. Collectively, our findings describe a novel post-translational modification of a TRAF family member and reveal a link between SUMOylation and TRAF-mediated signal transduction.
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Affiliation(s)
- Sophia Miliara
- Molecular and Cellular Biology Laboratory, University of Crete School of Medicine, Heraklion, Greece
- Laboratory of Cancer Biology, Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology Hellas, Heraklion, Greece
| | - Kalliopi K. Gkouskou
- Molecular and Cellular Biology Laboratory, University of Crete School of Medicine, Heraklion, Greece
- Laboratory of Cancer Biology, Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology Hellas, Heraklion, Greece
| | - Tyson V. Sharp
- Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Aristides G. Eliopoulos
- Molecular and Cellular Biology Laboratory, University of Crete School of Medicine, Heraklion, Greece
- Laboratory of Cancer Biology, Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology Hellas, Heraklion, Greece
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29
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Shkoda A, Town JA, Griese J, Romio M, Sarioglu H, Knöfel T, Giehler F, Kieser A. The germinal center kinase TNIK is required for canonical NF-κB and JNK signaling in B-cells by the EBV oncoprotein LMP1 and the CD40 receptor. PLoS Biol 2012; 10:e1001376. [PMID: 22904686 PMCID: PMC3419181 DOI: 10.1371/journal.pbio.1001376] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 07/06/2012] [Indexed: 01/04/2023] Open
Abstract
TNIK has an important function in physiological activation and viral transformation of human B-cells by interacting with the TRAF6 adapter complex and mediating NF-κB and JNK signal transduction. The tumor necrosis factor-receptor-associated factor 2 (TRAF2)- and Nck-interacting kinase (TNIK) is a ubiquitously expressed member of the germinal center kinase family. The TNIK functions in hematopoietic cells and the role of TNIK-TRAF interaction remain largely unknown. By functional proteomics we identified TNIK as interaction partner of the latent membrane protein 1 (LMP1) signalosome in primary human B-cells infected with the Epstein-Barr tumor virus (EBV). RNAi-mediated knockdown proved a critical role for TNIK in canonical NF-κB and c-Jun N-terminal kinase (JNK) activation by the major EBV oncoprotein LMP1 and its cellular counterpart, the B-cell co-stimulatory receptor CD40. Accordingly, TNIK is mandatory for proliferation and survival of EBV-transformed B-cells. TNIK forms an activation-induced complex with the critical signaling mediators TRAF6, TAK1/TAB2, and IKKβ, and mediates signalosome formation at LMP1. TNIK directly binds TRAF6, which bridges TNIK's interaction with the C-terminus of LMP1. Separate TNIK domains are involved in NF-κB and JNK signaling, the N-terminal TNIK kinase domain being essential for IKKβ/NF-κB and the C-terminus for JNK activation. We therefore suggest that TNIK orchestrates the bifurcation of both pathways at the level of the TRAF6-TAK1/TAB2-IKK complex. Our data establish TNIK as a novel key player in TRAF6-dependent JNK and NF-κB signaling and a transducer of activating and transforming signals in human B-cells. The germinal center kinase family member TNIK was discovered in a yeast-two-hybrid screen for interaction partners of the adapter proteins TRAF2 and Nck, and here we show it is one of the missing molecular players in two key signaling pathways in B-lymphocytes. We found that TNIK is crucial for the activities of the CD40 receptor on Bcells and its viral mimic, the latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV). EBV is a human DNA tumor virus that is associated with various malignancies. It targets and transforms B-cells by hijacking the cellular signaling machinery via its oncogene LMP1. In normal Bcell physiology, the CD40 receptor is central to the immune response by mediating B-cell activation and proliferation. TNIK turns out to be an organizer of the LMP1- and CD40-induced signaling complexes by interacting with the TRAF6 adapter protein, well known for its role in linking distinct signaling pathways. Through this mechanism the two receptors depend on TNIK to activate the canonical NF-κB and JNK signal transduction pathways, which are important for the physiological activation of B-cells (a process that enables antibody production), as well as for their transformation into tumor cells. TNIK thus constitutes a key player in the transmission of physiological and pathological signals in human B-cells that might serve as a future therapeutic target against B-cell malignancies.
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Affiliation(s)
- Anna Shkoda
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Jennifer A. Town
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Janine Griese
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Michael Romio
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Hakan Sarioglu
- Research Unit Protein Science, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Thomas Knöfel
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Fabian Giehler
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
| | - Arnd Kieser
- Research Unit Gene Vectors, Helmholtz Zentrum München - German Research Center for Environmental Health, München, Germany
- * E-mail:
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Pérez-Chacón G, Llobet D, Pardo C, Pindado J, Choi Y, Reed JC, Zapata JM. TNFR-associated factor 2 deficiency in B lymphocytes predisposes to chronic lymphocytic leukemia/small lymphocytic lymphoma in mice. THE JOURNAL OF IMMUNOLOGY 2012; 189:1053-61. [PMID: 22711886 DOI: 10.4049/jimmunol.1200814] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously shown that transgenic (tg) mice expressing in B lymphocytes both BCL-2 and a TNFR-associated factor 2 (TRAF2) mutant lacking the really interesting new gene and zinc finger domains (TRAF2DN) develop small lymphocytic lymphoma and chronic lymphocytic leukemia with high incidence (Zapata et al. 2004. Proc. Nat. Acad. Sci. USA 101: 16600-16605). Further analysis of the expression of TRAF2 and TRAF2DN in purified B cells demonstrated that expression of both endogenous TRAF2 and tg TRAF2DN was negligible in Traf2DN-tg B cells compared with wild-type mice. This was the result of proteasome-dependent degradation, and rendered TRAF2DN B cells as bona fide TRAF2-deficient B cells. Similar to B cells with targeted Traf2 deletion, Traf2DN-tg mice show expanded marginal zone B cell population and have constitutive p100 NF-κB2 processing. Also, TRAF3, X-linked inhibitor of apoptosis, and Bcl-X(L) expression levels were increased, whereas cellular inhibitors of apoptosis 1 and 2 levels were drastically reduced compared with those found in wild-type B cells. Moreover, consistent with previous results, we also show that TRAF2 was required for efficient JNK and ERK activation in response to CD40 engagement. However, TRAF2 was deleterious for BCR-mediated activation of these kinases. In contrast, TRAF2 deficiency had no effect on CD40-mediated p38 MAPK activation but significantly reduced BCR-mediated p38 activation. Finally, we further confirm that TRAF2 was required for CD40-mediated proliferation, but its absence relieved B cells of the need for B cell activating factor for survival. Altogether, our results suggest that TRAF2 deficiency cooperates with BCL-2 in promoting chronic lymphocytic leukemia/small lymphocytic lymphoma in mice, possibly by specifically enforcing marginal zone B cell accumulation, increasing X-linked inhibitor of apoptosis expression, and rendering B cells independent of B cell activating factor for survival.
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31
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Vrazo AC, Chauchard M, Raab-Traub N, Longnecker R. Epstein-Barr virus LMP2A reduces hyperactivation induced by LMP1 to restore normal B cell phenotype in transgenic mice. PLoS Pathog 2012; 8:e1002662. [PMID: 22536156 PMCID: PMC3334893 DOI: 10.1371/journal.ppat.1002662] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 03/08/2012] [Indexed: 12/15/2022] Open
Abstract
Epstein-Barr virus (EBV) latently infects most of the human population and is strongly associated with lymphoproliferative disorders. EBV encodes several latency proteins affecting B cell proliferation and survival, including latent membrane protein 2A (LMP2A) and the EBV oncoprotein LMP1. LMP1 and LMP2A signaling mimics CD40 and BCR signaling, respectively, and has been proposed to alter B cell functions including the ability of latently-infected B cells to access and transit the germinal center. In addition, several studies suggested a role for LMP2A modulation of LMP1 signaling in cell lines by alteration of TRAFs, signaling molecules used by LMP1. In this study, we investigated whether LMP1 and LMP2A co-expression in a transgenic mouse model alters B cell maturation and the response to antigen, and whether LMP2A modulates LMP1 function. Naïve LMP1/2A mice had similar lymphocyte populations and antibody production by flow cytometry and ELISA compared to controls. In the response to antigen, LMP2A expression in LMP1/2A animals rescued the impairment in germinal center generation promoted by LMP1. LMP1/2A animals produced high-affinity, class-switched antibody and plasma cells at levels similar to controls. In vitro, LMP1 upregulated activation markers and promoted B cell hyperproliferation, and co-expression of LMP2A restored a wild-type phenotype. By RT-PCR and immunoblot, LMP1 B cells demonstrated TRAF2 levels four-fold higher than non-transgenic controls, and co-expression of LMP2A restored TRAF2 levels to wild-type levels. No difference in TRAF3 levels was detected. While modulation of other TRAF family members remains to be assessed, normalization of the LMP1-induced B cell phenotype through LMP2A modulation of TRAF2 may be a pathway by which LMP2A controls B cell function. These findings identify an advance in the understanding of how Epstein-Barr virus can access the germinal center in vivo, a site critical for both the genesis of immunological memory and of virus-associated tumors. As a ubiquitous human pathogen, Epstein-Barr virus (EBV) infection is associated with several human B cell diseases characterized by inappropriate B cell activation and function, including infectious mononucleosis and certain cancers. EBV latent membrane protein 1 (LMP1) and 2A (LMP2A) hijack cell signaling pathways to alter B cell activation and function, and are detected in EBV-associated diseases. Defining the effect on B cell function when LMP1 and LMP2A are expressed together in the same cell is critical to understanding how EBV subverts normal B cell behavior before disease develops. Using transgenic mice, we have demonstrated that LMP2A dampens cellular proliferation and activation induced by LMP1, which may be due to the LMP2A-associated decrease in the levels of TRAF2, a signaling protein used by LMP1. LMP2A also allows B cells carrying LMP1 to enter the germinal center during an immune response, a site that gives rise to EBV-associated tumors in humans. In sum, this study highlights the biological outcomes of LMP1 and LMP2A co-expression in B cells and contributes to the knowledge of how EBV subverts normal B cell behavior before disease develops.
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Affiliation(s)
- Alexandra C. Vrazo
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Maria Chauchard
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Center for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Nancy Raab-Traub
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Richard Longnecker
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail:
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32
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Abstract
The noncanonical nuclear factor-κB (NF-κB) signaling pathway mediates activation of the p52/RelB NF-κB complex and, thereby, regulates specific immunological processes. This NF-κB pathway relies on the inducible processing of NF-κB2 precursor protein, p100, as opposed to the degradation of IκBα in the canonical NF-κB pathway. A central signaling component of the noncanonical NF-κB pathway is NF-κB-inducing kinase (NIK), which functions together with a downstream kinase, IKKα (inhibitor of NF-κB kinase α), to induce phosphorylation-dependent ubiquitination and processing of p100. Under normal conditions, NIK is targeted for continuous degradation by a tumor necrosis factor (TNF) receptor-associated factor-3 (TRAF3)-dependent E3 ubiquitin ligase. In response to signals mediated by a subset of TNF receptor superfamily members, NIK becomes stabilized as a result of TRAF3 degradation, leading to the activation of noncanonical NF-κB. This review discusses both the historical perspectives and the recent progress in the regulation and biological function of the noncanonical NF-κB pathway.
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Affiliation(s)
- Shao-Cong Sun
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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Gommerman JL, Summers deLuca L. LTβR and CD40: working together in dendritic cells to optimize immune responses. Immunol Rev 2012; 244:85-98. [PMID: 22017433 DOI: 10.1111/j.1600-065x.2011.01056.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Generating an immune response tailored to destroy an infecting organism while limiting bystander damage involves guiding T-cell activation using a variety of cues taken from the immunogen (antigen type, dose, and persistence, accompanying danger signals) as well as the host (tissue environment, T-cell frequency, and affinity for antigen). Dendritic cells (DCs) serve as translators of much of this information and are critically required for effective pathogen and tumor clearance. Moreover, dysregulation of DC activation can lead to autoimmunity. Inhibition of the lymphotoxin (LT) and CD40 pathways has been shown to be effective at quieting inflammation in settings where DC-T-cell interactions are key instigators of disease progression. In this review, we compare and contrast the CD40 and LT pathways in the context of receptor/ligand expression, signal transduction, and DC biology. We provide evidence that these two pathways play complementary roles in DC cytokine secretion, thus indirectly shaping the nature of the CD8(+) T-cell response to foreign antigen. Given the distinct role of these pathways in the context of DC function, we propose that dual therapies targeted at both the CD40 and LTβ receptor may have therapeutic potential in silencing DC-driven autoimmunity or in promoting tumor clearance.
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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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35
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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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36
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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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37
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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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38
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HOIL-1L interacting protein (HOIP) is essential for CD40 signaling. PLoS One 2011; 6:e23061. [PMID: 21829693 PMCID: PMC3148254 DOI: 10.1371/journal.pone.0023061] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 07/12/2011] [Indexed: 11/19/2022] Open
Abstract
CD40 is a cell surface receptor important in the activation of antigen-presenting cells during immune responses. In macrophages and dendritic cells, engagement of CD40 by its ligand CD154 provides signals critical for anti-microbial and T cell-mediated immune responses, respectively. In B cells, CD40 signaling has a major role in regulating cell proliferation, antibody production, and memory B cell development. CD40 engagement results in the formation of a receptor-associated complex that mediates activation of NF-κB, stress-activated protein kinases, and other signaling molecules. However, the mechanisms that link CD40 to these signaling events have been only partially characterized. Known components of the CD40 signaling complex include members of the TNF receptor-associated factor (TRAF) family of proteins. We previously showed that the TRAF family member TRAF2 mediates recruitment of HOIL-1L-interacting protein (HOIP) to the cytoplasmic domain of CD40, suggesting that HOIP has a role in the CD40 signaling pathway. To determine the role of HOIP in CD40 signaling, we used somatic cell gene targeting to generate mouse B cell lines deficient in HOIP. We found that the CD40-induced upregulation of CD80 and activation of germline immunoglobulin epsilon transcription were defective in HOIP-deficient cells. We also found that the CD40-mediated activation of NF-κB and c-Jun kinase was impaired. Recruitment of IκB kinase proteins to the CD40 signaling complex was undetectable in HOIP-deficient cells, potentially explaining the defect in NF-κB activation. Restoration of HOIP expression reversed the defects in cellular activation and signaling. These results reveal HOIP as a key component of the CD40 signaling pathway.
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39
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CDK-mediated regulation of cell functions via c-Jun phosphorylation and AP-1 activation. PLoS One 2011; 6:e19468. [PMID: 21559334 PMCID: PMC3084876 DOI: 10.1371/journal.pone.0019468] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 03/30/2011] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) and their targets have been primarily associated with regulation of cell-cycle progression. Here we identify c-Jun, a transcription factor involved in the regulation of a broad spectrum of cellular functions, as a newly recognized CDK substrate. Using immune cells from mouse and human, and several complementary in vitro and in vivo approaches including dominant negative protein expression, pharmacologic inhibitors, kinase assays and CDK4 deficient cells, we demonstrate the ability of CDK4 to phosphorylate c-Jun. Additionally, the activity of AP-1, a ubiquitous transcription factor containing phosphorylated c-Jun as a subunit, was inhibited by abrogating CDK4. Surprisingly, the regulation of c-Jun phosphorylation by CDK4 occurred in non-dividing cells, indicating that this pathway is utilized for cell functions that are independent of proliferation. Our studies identify a new substrate for CDK4 and suggest a mechanism by which CDKs can regulate multiple cellular activation functions, not all of which are directly associated with cell cycle progression. These findings point to additional roles of CDKs in cell signaling and reveal potential implications for therapeutic manipulations of this kinase pathway.
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40
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Lu P, Hankel IL, Hostager BS, Swartzendruber JA, Friedman AD, Brenton JL, Rothman PB, Colgan JD. The developmental regulator protein Gon4l associates with protein YY1, co-repressor Sin3a, and histone deacetylase 1 and mediates transcriptional repression. J Biol Chem 2011; 286:18311-9. [PMID: 21454521 DOI: 10.1074/jbc.m110.133603] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Genetic studies involving zebrafish and mice have demonstrated that the protein Gon4l (Gon4-like) is essential for hematopoiesis. These studies also suggested that Gon4l regulates gene expression during hematopoietic development, yet the biochemical function of Gon4l has not been defined. Here, we describe the identification of factors that interact with Gon4l and may cooperate with this protein to regulate gene expression. As predicted by polypeptide sequence conservation, Gon4l interacted and co-localized with the DNA-binding protein YY1 (Yin Yang 1). Density gradient sedimentation analysis of protein lysates from mouse M12 B cells showed that Gon4l and YY1 co-sediment with the transcriptional co-repressor Sin3a and its functional partner histone deacetylase (HDAC) 1. Consistent with these results, immunoprecipitation studies showed that Gon4l associates with Sin3a, HDAC1, and YY1 as a part of complexes that form in M12 cells. Sequential immunoprecipitation studies demonstrated that Gon4l, YY1, Sin3a, and HDAC1 could all associate as components of a single complex and that a conserved domain spanning the central portion of Gon4l was required for formation of this complex. When targeted to DNA, Gon4l repressed the activity of a nearby promoter, which correlated with the ability to interact with Sin3a and HDAC1. Our data suggest that Sin3a, HDAC1, and YY1 are co-factors for Gon4l and that Gon4l may function as a platform for the assembly of complexes that regulate gene expression.
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Affiliation(s)
- Ping Lu
- Interdisciplinary Immunology Graduate Program, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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41
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Arcipowski KM, Stunz LL, Graham JP, Kraus ZJ, Bush TJV, Bishop GA. Molecular mechanisms of TNFR-associated factor 6 (TRAF6) utilization by the oncogenic viral mimic of CD40, latent membrane protein 1 (LMP1). J Biol Chem 2011; 286:9948-55. [PMID: 21262968 PMCID: PMC3060549 DOI: 10.1074/jbc.m110.185983] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 01/19/2011] [Indexed: 11/06/2022] Open
Abstract
Latent membrane protein 1 (LMP1), encoded by Epstein-Barr virus, is required for EBV-mediated B cell transformation and plays a significant role in the development of posttransplant B cell lymphomas. LMP1 has also been implicated in exacerbation of autoimmune diseases such as systemic lupus erythematosus. LMP1 is a constitutively active functional mimic of the tumor necrosis factor receptor superfamily member CD40, utilizing tumor necrosis factor receptor-associated factor (TRAF) adaptor proteins to induce signaling. However, LMP1-mediated B cell activation is amplified and sustained compared with CD40. We have previously shown that LMP1 and CD40 use TRAFs 1, 2, 3, and 5 differently. TRAF6 is important for CD40 signaling, but the role of TRAF6 in LMP1 signaling in B cells is not clear. Although TRAF6 binds directly to CD40, TRAF6 interaction with LMP1 in B cells has not been characterized. Here we tested the hypothesis that TRAF6 is a critical regulator of LMP1 signaling in B cells, either as part of a receptor-associated complex and/or as a cytoplasmic adaptor protein. Using TRAF6-deficient B cells, we determined that TRAF6 was critical for LMP1-mediated B cell activation. Although CD40-mediated TRAF6-dependent signaling does not require the TRAF6 receptor-binding domain, we found that LMP1 signaling required the presence of this domain. Furthermore, TRAF6 was recruited to the LMP1 signaling complex via the TRAF1/2/3/5 binding site within the cytoplasmic domain of LMP1.
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MESH Headings
- Animals
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- B-Lymphocytes/virology
- CD40 Antigens/genetics
- CD40 Antigens/immunology
- CD40 Antigens/metabolism
- Cell Transformation, Viral/genetics
- Cell Transformation, Viral/immunology
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/immunology
- Herpesvirus 4, Human/metabolism
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/immunology
- Lupus Erythematosus, Systemic/metabolism
- Lupus Erythematosus, Systemic/virology
- Lymphocyte Activation/genetics
- Lymphocyte Activation/immunology
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell/metabolism
- Lymphoma, B-Cell/virology
- Mice
- Mice, Knockout
- Molecular Mimicry/genetics
- Molecular Mimicry/immunology
- Protein Structure, Tertiary
- Signal Transduction/immunology
- TNF Receptor-Associated Factor 6/genetics
- TNF Receptor-Associated Factor 6/immunology
- TNF Receptor-Associated Factor 6/metabolism
- Viral Matrix Proteins/genetics
- Viral Matrix Proteins/immunology
- Viral Matrix Proteins/metabolism
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Affiliation(s)
- Kelly M. Arcipowski
- From the Interdisciplinary Graduate Programs in Molecular and Cellular Biology and
| | | | | | | | | | - Gail A. Bishop
- From the Interdisciplinary Graduate Programs in Molecular and Cellular Biology and
- Immunology and
- the Departments of Microbiology and
- Internal Medicine, University of Iowa and
- the Veterans Affairs Medical Center, Iowa City, Iowa 52242
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42
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Abstract
The non-canonical NF-κB pathway is an important arm of NF-κB signaling that predominantly targets activation of the p52/RelB NF-κB complex. This pathway depends on the inducible processing of p100, a molecule functioning as both the precursor of p52 and a RelB-specific inhibitor. A central signaling component of the non-canonical pathway is NF-κB-inducing kinase (NIK), which integrates signals from a subset of TNF receptor family members and activates a downstream kinase, IκB kinase-α (IKKα), for triggering p100 phosphorylation and processing. A unique mechanism of NIK regulation is through its fate control: the basal level of NIK is kept low by a TRAF-cIAP destruction complex and signal-induced non-canonical NF-κB signaling involves NIK stabilization. Tight control of the fate of NIK is important, since deregulated NIK accumulation is associated with lymphoid malignancies.
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Affiliation(s)
- Shao-Cong Sun
- Department of Immunology, The University of Texas MD Anderson Cancer Center, The University of Texas Graduate School of Biomedical Sciences at Houston, 7455 Fannin Street, Box 902, Houston, TX 77030, USA.
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43
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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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44
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Yacoub D, Hachem A, Théorêt JF, Gillis MA, Mourad W, Merhi Y. Enhanced levels of soluble CD40 ligand exacerbate platelet aggregation and thrombus formation through a CD40-dependent tumor necrosis factor receptor-associated factor-2/Rac1/p38 mitogen-activated protein kinase signaling pathway. Arterioscler Thromb Vasc Biol 2010; 30:2424-33. [PMID: 21071692 DOI: 10.1161/atvbaha.110.216143] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE CD40 ligand is a thromboinflammatory molecule that predicts cardiovascular events. Platelets constitute the major source of soluble CD40 ligand (sCD40L), which has been shown to influence platelet activation, although its exact functional impact on platelets and the underlying mechanisms remain undefined. We aimed to determine the impact and the signaling mechanisms of sCD40L on platelets. METHODS AND RESULTS sCD40L strongly enhances platelet activation and aggregation. Human platelets treated with a mutated form of sCD40L that does not bind CD40, and CD40(-/-) mouse platelets failed to elicit such responses. Furthermore, sCD40L stimulation induces the association of the tumor necrosis factor receptor-associated factor-2 with platelet CD40. Notably, sCD40L primes platelets through activation of the small GTPase Rac1 and its downstream target p38 mitogen-activated protein kinase, which leads to platelet shape change and actin polymerization. Moreover, sCD40L exacerbates thrombus formation and leukocyte infiltration in wild-type mice but not in CD40(-/-) mice. CONCLUSIONS sCD40L enhances agonist-induced platelet activation and aggregation through a CD40-dependent tumor necrosis factor receptor-associated factor-2/Rac1/p38 mitogen-activated protein kinase signaling pathway. Thus, sCD40L is an important platelet primer predisposing platelets to enhanced thrombus formation in response to vascular injury. This may explain the link between circulating levels of sCD40L and cardiovascular diseases.
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Affiliation(s)
- Daniel Yacoub
- Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, Montreal, Quebec, Canada
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45
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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: 81] [Impact Index Per Article: 5.8] [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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46
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Peters AL, Bishop GA. Differential TRAF3 utilization by a variant human CD40 receptor with enhanced signaling. THE JOURNAL OF IMMUNOLOGY 2010; 185:6555-62. [PMID: 21041727 DOI: 10.4049/jimmunol.1000135] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD40 is required for T cell-dependent humoral immunity, but it can also contribute to the pathogenesis of autoimmunity and B cell malignancy. The TNFR-associated factor (TRAF)2 and TRAF6 adaptor proteins are positive regulators of CD40 signaling required to activate downstream kinase cascades and transcription factors. In contrast, TRAF3 can serve as a negative regulator of CD40 signaling, and CD40 signals are amplified in TRAF3(-/-) B cells. We previously reported a gain-of-function polymorphism of the human CD40 receptor, hCD40-P227A, which signals in an amplified manner to B lymphocytes. In this study, we show that hCD40-P227A binds more TRAF3 and TRAF5, as well as certain associated proteins, than wild-type-CD40. Studies in TRAF-deficient B cell lines revealed that hCD40-P227A uses TRAF3 as a positive rather than negative regulator. Although located outside of any known TRAF binding sites, the P227A polymorphism can alter TRAF binding and dramatically changes the role played by TRAF3 in CD40 signaling.
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Affiliation(s)
- Anna L Peters
- Medical Scientist Training Program and Immunology Graduate Program, University of Iowa, Iowa City, IA 52240, USA
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47
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Abstract
Members of the nuclear factor-κB (NF-κB) family of transcription factors play critical roles in regulating the expression of genes whose products are involved in inflammation, the immune response, cell proliferation, and the suppression of both death receptor- and stress-induced apoptosis. Abnormal NF-κB activation has been observed in various inflammatory diseases and many types of cancers. Gene knockout studies have clearly demonstrated that most of the physiologically relevant stimuli that activate NF-κB converge on inhibitor of κB kinase (IKK). Although the mechanism by which IKK activates NF-κB is well established, the upstream signaling mechanisms-those that underlie IKK activation by IKK kinases (IKK-Ks)-are not yet fully understood. The current belief is that members of the TNF receptor-associated factor (TRAF) family function as ubiquitin E3 ligases that catalyze non-canonical polyubiquitination of adaptor proteins, and that the ubiquitinated adaptor proteins in turn serve as platforms to recruit IKK and IKK-Ks, facilitating IKK activation through proximity-mediated phosphorylation. This review will focus on the most recent findings relating to the role of TRAFs-mediated protein ubiquitination in regulating IKK activation, and highlight the newly emerging complexity of protein ubiquitination in receptor-induced NF-κB activation.
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Affiliation(s)
- Hasem Habelhah
- Department of Pathology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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48
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Meads MB, Li ZW, Dalton WS. A novel TNF receptor-associated factor 6 binding domain mediates NF-kappa B signaling by the common cytokine receptor beta subunit. THE JOURNAL OF IMMUNOLOGY 2010; 185:1606-15. [PMID: 20622119 DOI: 10.4049/jimmunol.0902026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
GM-CSF, IL-3, and IL-5 are proinflammatory cytokines that control the production and function of myeloid and lymphoid cells. Their receptors are composed of a ligand-specific alpha subunit and a shared common signal-transducing beta subunit (beta common receptor or GM-CSFR beta [beta(c)]). The pleiotropic nature of biologic outcomes mediated by beta(c) and the presence of large, uncharacterized regions of its cytoplasmic domain suggest that much remains to be learned about its downstream signaling pathways. Although some previous work has attempted to link beta(c) with NF-kappaB activation, a definitive mechanism that mediates this pathway has not been described and, to date, it has not been clear whether the receptor can directly activate NF-kappaB. We demonstrate that NF-kappaB activation by beta(c) is dependent on TNFR-associated factor 6 (TRAF6) and that association of TRAF6 with beta(c) requires a consensus-binding motif found in other molecules known to interact with TRAF6. Furthermore, point mutation of this motif abrogated the ability of beta(c) to mediate NF-kappaB activation and reduced the viability of an IL-3-dependent hematopoietic cell line. Because this receptor plays a key role in hematopoiesis and the beta(c) cytoplasmic domain identified in this work mediates hematopoietic cell viability, this new pathway is likely to contribute to immune cell biology. This work is significant because it is the first description of a TRAF6-dependent signaling pathway associated with a type I cytokine receptor. It also suggests that TRAF6, a mediator of TNFR and TLR signaling, may be a common signaling intermediate in diverse cytokine receptor systems.
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Affiliation(s)
- Mark B Meads
- Department of Experimental Therapeutics and Oncologic Sciences, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, FL 33612, USA
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49
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Hostager BS, Fox DK, Whitten D, Wilkerson CG, Eipper BA, Francone VP, Rothman PB, Colgan JD. HOIL-1L interacting protein (HOIP) as an NF-kappaB regulating component of the CD40 signaling complex. PLoS One 2010; 5:e11380. [PMID: 20614026 PMCID: PMC2894856 DOI: 10.1371/journal.pone.0011380] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 06/07/2010] [Indexed: 11/25/2022] Open
Abstract
The tumor necrosis factor receptor (TNFR) superfamily mediates signals critical for regulation of the immune system. One family member, CD40, is important for the efficient activation of antibody-producing B cells and other antigen-presenting cells. The molecules and mechanisms that mediate CD40 signaling are only partially characterized. Proteins known to interact with the cytoplasmic domain of CD40 include members of the TNF receptor-associated factor (TRAF) family, which regulate signaling and serve as links to other signaling molecules. To identify additional proteins important for CD40 signaling, we used a combined stimulation/immunoprecipitation procedure to isolate CD40 signaling complexes from B cells and characterized the associated proteins by mass spectrometry. In addition to known CD40-interacting proteins, we detected SMAC/DIABLO, HTRA2/Omi, and HOIP/RNF31/PAUL/ZIBRA. We found that these previously unknown CD40-interacting partners were recruited in a TRAF2-dependent manner. HOIP is a ubiquitin ligase capable of mediating NF-κB activation through the ubiquitin-dependent activation of IKKγ. We found that a mutant HOIP molecule engineered to lack ubiquitin ligase activity inhibited the CD40-mediated activation of NF-κB. Together, our results demonstrate a powerful approach for the identification of signaling molecules associated with cell surface receptors and indicate an important role for the ubiquitin ligase activity of HOIP in proximal CD40 signaling.
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Affiliation(s)
- Bruce S Hostager
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America.
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50
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Lindqvist C, Sandin LC, Fransson M, Loskog A. Local AdCD40L gene therapy is effective for disseminated murine experimental cancer by breaking T-cell tolerance and inducing tumor cell growth inhibition. J Immunother 2010; 32:785-92. [PMID: 19752755 DOI: 10.1097/cji.0b013e3181acea69] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
CD40 ligand (CD40L) is one of the most potent stimulators of Th1-type immunity through its maturation of dendritic cells that, in turn, stimulate effector cells such as T cells and NK cells. Lately, CD40-mediated cell growth inhibition and apoptosis have been in focus for the development of novel cancer treatment regiments, including recombinant soluble CD40L or CD40-stimulating antibodies. In this study, intravesical CD40L gene transfer through adenoviral vectors (AdCD40L) was used to treat an aggressive model of disseminated bladder cancer (MB49/C57BL/6). Three weekly AdCD40L vector instillations increased overall survival of tumor-bearing mice (mean 18.5 d, control mice 13 d). Furthermore, bladder tumors were eradicated (2 of 10) simultaneously as lung metastases (6 of 10) were cleared. FoxP3 levels were similar in the tumors of AdCD40L-treated mice and control mice but the tumor-infiltrating effector T cells in AdCD40L-treated mice were cytotoxic (CD107a+) in contrast to those in control-treated tumors. Furthermore, AdCD40L gene therapy could induce cell growth inhibition and cell death in the MB49 tumor cells in vitro and in vivo. However, this effect was not potent enough to cure growing tumors in immunodeficient mice. In conclusion, AdCD40L gene therapy is potent for disseminated cancer both by activation of T cells and controlling tumor cell growth and viability.
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Affiliation(s)
- Camilla Lindqvist
- Clinical Immunology Division, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
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