1
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Nobari ST, Nojadeh JN, Talebi M. B-cell maturation antigen targeting strategies in multiple myeloma treatment, advantages and disadvantages. J Transl Med 2022; 20:82. [PMID: 35144648 PMCID: PMC8832753 DOI: 10.1186/s12967-022-03285-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/29/2022] [Indexed: 01/02/2023] Open
Abstract
B cell maturation antigen (BCMA), a transmembrane glycoprotein member of the tumor necrosis factor receptor superfamily 17 (TNFRSF17), highly expressed on the plasma cells of Multiple myeloma (MM) patients, as well as the normal population. BCMA is used as a biomarker for MM. Two members of the TNF superfamily proteins, including B-cell activating factor (BAFF) and A proliferation-inducing ligand (APRIL), are closely related to BCMA and play an important role in plasma cell survival and progression of MM. Despite the maximum specificity of the monoclonal antibody technologies, introducing the tumor-specific antigen(s) is not applicable for all malignancies, such as MM that there plenty of relatively specific antigens such as GPCR5D, MUC1, SLAMF7 and etc., but higher expression of BCMA on these cells in comparison with normal ones can be regarded as a relatively exclusive marker. Currently, different monoclonal antibody (mAb) technologies applied in anti-MM therapies such as daratuzumab, SAR650984, GSK2857916, and CAR-T cell therapies are some of these tools that are reviewed in the present manuscript. By the way, the structure, function, and signaling of the BCMA and related molecule(s) role in normal plasma cells and MM development, evaluated as well as the potential side effects of its targeting by different CAR-T cells generations. In conclusion, BCMA can be regarded as an ideal molecule to be targeted in immunotherapeutic methods, regarding lower potential systemic and local side effects.
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Affiliation(s)
- Shirin Teymouri Nobari
- Department of Medical Biochemistry, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Jafar Nouri Nojadeh
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mehdi Talebi
- Department of Applied Cells Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
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2
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Getahun A. Role of inhibitory signaling in peripheral B cell tolerance*. Immunol Rev 2022; 307:27-42. [PMID: 35128676 PMCID: PMC8986582 DOI: 10.1111/imr.13070] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 12/16/2022]
Abstract
At least 20% of B cells in the periphery expresses an antigen receptor with a degree of self-reactivity. If activated, these autoreactive B cells pose a risk as they can contribute to the development of autoimmune diseases. To prevent their activation, both B cell-intrinsic and extrinsic tolerance mechanisms are in place in healthy individuals. In this review article, I will focus on B cell-intrinsic mechanisms that prevent the activation of autoreactive B cells in the periphery. I will discuss how inhibitory signaling circuits are established in autoreactive B cells, focusing on the Lyn-SHIP-1-SHP-1 axis, how they contribute to peripheral immune tolerance, and how disruptions of these circuits can contribute to the development of autoimmunity.
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Affiliation(s)
- Andrew Getahun
- Department of Immunology and Microbiology University of Colorado SOM Aurora Colorado USA
- Department of Immunology and Genomic Medicine National Jewish Health Denver Colorado USA
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3
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Suppressed humoral immunity is associated with dengue nonstructural protein NS1-elicited anti-death receptor antibody fractions in mice. Sci Rep 2020; 10:6294. [PMID: 32286343 PMCID: PMC7156414 DOI: 10.1038/s41598-020-62958-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 03/12/2020] [Indexed: 02/08/2023] Open
Abstract
Dengue virus (DENV) infections may cause life-threatening dengue hemorrhagic fever (DHF). Suppressed protective immunity was shown in these patients. Although several hypotheses have been formulated, the mechanism of DENV-induced immunosuppression remains unclear. Previously, we found that cross-reactive antibodies against tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 1 (death receptor 4 [DR4]) were elicited in DHF patients, and that anti-DR4 autoantibody fractions were elicited by nonstructural protein 1 (NS1) immunizations in experimental mice. In this study, we found that anti-DR4 antibodies could suppress B lymphocyte function in vitro and in vivo. Treatment with the anti-DR4 immunoglobulin (Ig) induced caspase-dependent cell death in immortalized B lymphocyte Raji cells in vitro. Anti-DR4 Igs elicited by NS1 and DR4 immunizations markedly suppressed mouse spleen transitional T2 B (IgM+IgD+), bone marrow pre-pro-B (B220+CD43+), pre-B (B220+CD43-), and mature B cell (B220+IgD+) subsets in mice. Furthermore, functional analysis revealed that the pre-elicitation of anti-NS1 and anti-DR4 Ig titers suppressed subsequently neutralizing antibody production by immunization with DENV envelop protein. Our data suggest that the elicitation of anti-DR4 titers through DENV NS1 immunization plays a suppressive role in humoral immunity in mice.
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4
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He X, Kläsener K, Iype JM, Becker M, Maity PC, Cavallari M, Nielsen PJ, Yang J, Reth M. Continuous signaling of CD79b and CD19 is required for the fitness of Burkitt lymphoma B cells. EMBO J 2018; 37:e97980. [PMID: 29669863 PMCID: PMC5983214 DOI: 10.15252/embj.201797980] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 02/28/2018] [Accepted: 03/07/2018] [Indexed: 01/05/2023] Open
Abstract
Expression of the B-cell antigen receptor (BCR) is essential not only for the development but also for the maintenance of mature B cells. Similarly, many B-cell lymphomas, including Burkitt lymphoma (BL), require continuous BCR signaling for their tumor growth. This growth is driven by immunoreceptor tyrosine-based activation motif (ITAM) and PI3 kinase (PI3K) signaling. Here, we employ CRISPR/Cas9 to delete BCR and B-cell co-receptor genes in the human BL cell line Ramos. We find that Ramos B cells require the expression of the BCR signaling component Igβ (CD79b), and the co-receptor CD19, for their fitness and competitive growth in culture. Furthermore, we show that in the absence of any other BCR component, Igβ can be expressed on the B-cell surface, where it is found in close proximity to CD19 and signals in an ITAM-dependent manner. These data suggest that Igβ and CD19 are part of an alternative B-cell signaling module that use continuous ITAM/PI3K signaling to promote the survival of B lymphoma and normal B cells.
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Affiliation(s)
- Xiaocui He
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Kathrin Kläsener
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Joseena M Iype
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Martin Becker
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Palash C Maity
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Marco Cavallari
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Peter J Nielsen
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Jianying Yang
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Michael Reth
- BIOSS Centre For Biological Signaling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
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5
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Syrett CM, Sindhava V, Hodawadekar S, Myles A, Liang G, Zhang Y, Nandi S, Cancro M, Atchison M, Anguera MC. Loss of Xist RNA from the inactive X during B cell development is restored in a dynamic YY1-dependent two-step process in activated B cells. PLoS Genet 2017; 13:e1007050. [PMID: 28991910 PMCID: PMC5648283 DOI: 10.1371/journal.pgen.1007050] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 10/19/2017] [Accepted: 09/28/2017] [Indexed: 12/05/2022] Open
Abstract
X-chromosome inactivation (XCI) in female lymphocytes is uniquely regulated, as the inactive X (Xi) chromosome lacks localized Xist RNA and heterochromatin modifications. Epigenetic profiling reveals that Xist RNA is lost from the Xi at the pro-B cell stage and that additional heterochromatic modifications are gradually lost during B cell development. Activation of mature B cells restores Xist RNA and heterochromatin to the Xi in a dynamic two-step process that differs in timing and pattern, depending on the method of B cell stimulation. Finally, we find that DNA binding domain of YY1 is necessary for XCI in activated B cells, as ex-vivo YY1 deletion results in loss of Xi heterochromatin marks and up-regulation of X-linked genes. Ectopic expression of the YY1 zinc finger domain is sufficient to restore Xist RNA localization during B cell activation. Together, our results indicate that Xist RNA localization is critical for maintaining XCI in female lymphocytes, and that chromatin changes on the Xi during B cell development and the dynamic nature of YY1-dependent XCI maintenance in mature B cells predisposes X-linked immunity genes to reactivation. Females are predisposed to develop various autoimmune disorders, and the genetic basis for this susceptibility is the X-chromosome. X-linked genes are dosage compensated between sexes by X-chromosome Inactivation (XCI) during embryogenesis and maintained into adulthood. Here we show that the chromatin of the inactive X loses epigenetic modifications during B cell lineage development. We found that female mature B cells, which are the pathogenic cells in autoimmunity, have a dynamic two-step mechanism of maintaining XCI during stimulation. The transcription factor YY1, which regulates DNA looping during V(D)J recombination in B cells, is necessary for relocalizing Xist RNA back to the inactive X in activated B cells. YY1 deletion ex vivo in mature B cells impairs heterochromatin mark enrichment on the inactive X, and results in increased X-linked gene expression. We demonstrate that the DNA binding domain of YY1 is sufficient for localizing Xist RNA to the inactive X during B cell stimulation. Our study indicates that Xist RNA localization is critical for maintaining XCI in female lymphocytes. We propose that chromatin changes on the Xi during B cell development and the dynamic nature of YY1-dependent XCI maintenance in mature B cells predisposes X-linked immunity genes to reactivation.
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Affiliation(s)
- Camille M. Syrett
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
| | - Vishal Sindhava
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
- Department of Pathology, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Suchita Hodawadekar
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
| | - Arpita Myles
- Department of Pathology, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Guanxiang Liang
- Department of Pathology, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Yue Zhang
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
| | - Satabdi Nandi
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
| | - Michael Cancro
- Department of Pathology, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Michael Atchison
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
| | - Montserrat C. Anguera
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, United States of America
- * E-mail:
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6
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Hemon P, Renaudineau Y, Debant M, Le Goux N, Mukherjee S, Brooks W, Mignen O. Calcium Signaling: From Normal B Cell Development to Tolerance Breakdown and Autoimmunity. Clin Rev Allergy Immunol 2017; 53:141-165. [DOI: 10.1007/s12016-017-8607-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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7
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Mediation of transitional B cell maturation in the absence of functional Bruton's tyrosine kinase. Sci Rep 2017; 7:46029. [PMID: 28378771 PMCID: PMC5380950 DOI: 10.1038/srep46029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/08/2017] [Indexed: 01/09/2023] Open
Abstract
X-linked immune-deficient (Xid) mice, carrying a mutation in Bruton’s tyrosine kinase (Btk), have multiple B cell lineage differentiation defects. We now show that, while Xid mice showed only mild reduction in the frequency of the late transitional (T2) stage of peripheral B cells, the defect became severe when the Xid genotype was combined with either a CD40-null, a TCRbeta-null or an MHC class II (MHCII)-null genotype. Purified Xid T1 and T2 B cells survived poorly in vitro compared to wild-type (WT) cells. BAFF rescued WT but not Xid T1 and T2 B cells from death in culture, while CD40 ligation equivalently rescued both. Xid transitional B cells ex vivo showed low levels of the p100 protein substrate for non-canonical NF-kappaB signalling. In vitro, CD40 ligation induced equivalent activation of the canonical but not of the non-canonical NF-kappaB pathway in Xid and WT T1 and T2 B cells. CD40 ligation efficiently rescued p100-null T1 B cells from neglect-induced death in vitro. These data indicate that CD40-mediated signals, likely from CD4 T cells, can mediate peripheral transitional B cell maturation independent of Btk and the non-canonical NF-kappaB pathway, and thus contribute to the understanding of the complexities of peripheral B cell maturation.
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8
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Song J, Uyttersprot N, Classen S, Waisman A. The IgG1 B-cell receptor provides survival and proliferative signals analogue to the Igα but not the Igβ co-receptor. Eur J Immunol 2016; 46:1878-86. [PMID: 27218486 DOI: 10.1002/eji.201646396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/15/2016] [Accepted: 05/19/2016] [Indexed: 01/05/2023]
Abstract
The function of the IgM B-cell receptor (BCR) is dependent on intact signaling of the co-receptors Igα and Igβ, both of which contain a cytoplasmic tail bearing an immunoreceptor tyrosine-based activation motif. We have previously demonstrated that the cytoplasmic tail of the IgG1 BCR can partially compensate for the loss of the signaling moiety of Igα. Here, we show that unlike Igα, Igβ signaling is indispensable for the development and function of IgG1-expressing B cells. Deletion of the cytoplasmic signaling tail of Igβ compromised the survival and proliferation not only of IgM(+) B cells but also of IgG1-expressing B cells. In the absence of the signaling tail of Igβ, the transcription levels of the antiapoptotic gene bcl-xl and the cell-cycle gene ccnd2 were reduced, consistent with the observed defects in survival and proliferation. These results demonstrate functional differences between Igα and Igβ in the transduction of IgG1 BCR signal.
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Affiliation(s)
- Jian Song
- Institute for Molecular Medicine, University of Medical Centre of the Johannes, Gutenberg University of Mainz, Mainz, Germany.,Institute of Physiological Chemistry and Pathobiochemistry, University of Muenster, Muenster, Germany
| | | | - Sabine Classen
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Ari Waisman
- Institute for Molecular Medicine, University of Medical Centre of the Johannes, Gutenberg University of Mainz, Mainz, Germany
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9
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Levit-Zerdoun E, Becker M, Pohlmeyer R, Wilhelm I, Maity PC, Rajewsky K, Reth M, Hobeika E. Survival of Igα-Deficient Mature B Cells Requires BAFF-R Function. THE JOURNAL OF IMMUNOLOGY 2016; 196:2348-60. [PMID: 26843325 DOI: 10.4049/jimmunol.1501707] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 12/29/2015] [Indexed: 12/18/2022]
Abstract
Expression of a functional BCR is essential for the development of mature B cells and has been invoked in the control of their maintenance. To test this maintenance function in a new experimental setting, we used the tamoxifen-inducible mb1-CreER(T2) mouse strain to delete or truncate either the mb-1 gene encoding the BCR signaling subunit Igα or the VDJ segment of the IgH (H chain [HC]). In this system, Cre-mediated deletion of the mb-1 gene is accompanied by expression of a GFP reporter. We found that, although the Igα-deficient mature B cells survive for >20 d in vivo, the HC-deficient or Igα tail-truncated B cell population is short-lived, with the HC-deficient cells displaying signs of an unfolded protein response. We also show that Igα-deficient B cells still respond to the prosurvival factor BAFF in culture and require BAFF-R signaling for their in vivo maintenance. These results suggest that, under certain conditions, the loss of the BCR can be tolerated by mature B cells for some time, whereas HC-deficient B cells, potentially generated by aberrant somatic mutations in the germinal center, are rapidly eliminated.
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Affiliation(s)
- Ella Levit-Zerdoun
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology, 79108 Freiburg, Germany
| | - Martin Becker
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology, 79108 Freiburg, Germany
| | - Roland Pohlmeyer
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Isabel Wilhelm
- Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Palash Chandra Maity
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Klaus Rajewsky
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; and
| | - Michael Reth
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany;
| | - Elias Hobeika
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; Institute of Immunology, University Hospital Ulm, 89081 Ulm, Germany
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10
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Inoue T, Morita M, Hijikata A, Fukuda-Yuzawa Y, Adachi S, Isono K, Ikawa T, Kawamoto H, Koseki H, Natsume T, Fukao T, Ohara O, Yamamoto T, Kurosaki T. CNOT3 contributes to early B cell development by controlling Igh rearrangement and p53 mRNA stability. ACTA ACUST UNITED AC 2015; 212:1465-79. [PMID: 26238124 PMCID: PMC4548056 DOI: 10.1084/jem.20150384] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 07/16/2015] [Indexed: 11/07/2022]
Abstract
Inoue et al. report that CNOT3, a subunit of the CCR4–NOT deadenylase complex regulating mRNA decay and translational repression, controls Igh gene rearrangement and destabilizes the mRNA of the tumor suppressor p53. Loss of CNOT3 results in a block of pro- to pre–B cell transition. The CCR4–NOT deadenylase complex plays crucial roles in mRNA decay and translational repression induced by poly(A) tail shortening. Although the in vitro activities of each component of this complex have been well characterized, its in vivo role in immune cells remains unclear. Here we show that mice lacking the CNOT3 subunit of this complex, specifically in B cells, have a developmental block at the pro- to pre–B cell transition. CNOT3 regulated generation of germline transcripts in the VH region of the immunoglobulin heavy chain (Igh) locus, compaction of the locus, and subsequent Igh gene rearrangement and destabilized tumor suppressor p53 mRNA. The developmental defect in the absence of CNOT3 could be partially rescued by ablation of p53 or introduction of a pre-rearranged Igh transgene. Thus, our data suggest that the CCR4–NOT complex regulates B cell differentiation by controlling Igh rearrangement and destabilizing p53 mRNA.
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Affiliation(s)
- Takeshi Inoue
- Laboratory of Lymphocyte Differentiation, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Masahiro Morita
- Department of Biochemistry and Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Quebec H3A 1A3, Canada Department of Biochemistry and Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Atsushi Hijikata
- Laboratory for Integrative Genomics, Laboratory for Developmental Genetics, Laboratory for Immune Regeneration, and Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa 230-0045, Japan
| | - Yoko Fukuda-Yuzawa
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Shungo Adachi
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Koto-ku, Tokyo 135-0064, Japan
| | - Kyoichi Isono
- Laboratory for Integrative Genomics, Laboratory for Developmental Genetics, Laboratory for Immune Regeneration, and Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa 230-0045, Japan
| | - Tomokatsu Ikawa
- Laboratory for Integrative Genomics, Laboratory for Developmental Genetics, Laboratory for Immune Regeneration, and Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa 230-0045, Japan Laboratory for Lymphocyte Development, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan
| | - Hiroshi Kawamoto
- Laboratory for Lymphocyte Development, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan Department of Immunology, Institute for Frontier Medical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Haruhiko Koseki
- Laboratory for Integrative Genomics, Laboratory for Developmental Genetics, Laboratory for Immune Regeneration, and Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa 230-0045, Japan
| | - Tohru Natsume
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Koto-ku, Tokyo 135-0064, Japan
| | - Taro Fukao
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Osamu Ohara
- Laboratory for Integrative Genomics, Laboratory for Developmental Genetics, Laboratory for Immune Regeneration, and Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa 230-0045, Japan
| | - Tadashi Yamamoto
- Cell Signal Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Tomohiro Kurosaki
- Laboratory of Lymphocyte Differentiation, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan Laboratory for Integrative Genomics, Laboratory for Developmental Genetics, Laboratory for Immune Regeneration, and Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa 230-0045, Japan
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11
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Dörner T, Shock A, Goldenberg DM, Lipsky PE. The mechanistic impact of CD22 engagement with epratuzumab on B cell function: Implications for the treatment of systemic lupus erythematosus. Autoimmun Rev 2015. [PMID: 26212727 DOI: 10.1016/j.autrev.2015.07.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Epratuzumab is a B-cell-directed non-depleting monoclonal antibody that targets CD22. It is currently being evaluated in two phase 3 clinical trials in patients with systemic lupus erythematosus (SLE), a disease associated with abnormalities in B-cell function and activation. The mechanism of action of epratuzumab involves perturbation of the B-cell receptor (BCR) signalling complex and intensification of the normal inhibitory role of CD22 on the BCR, leading to reduced signalling and diminished activation of B cells. Such effects may result from down-modulation of CD22 upon binding by epratuzumab, as well as decreased expression of other proteins involved in amplifying BCR signalling capability, notably CD19. The net result is blunting the capacity of antigen engagement to induce B-cell activation. The functional consequences of epratuzumab binding to CD22 include diminished B-cell proliferation, effects on adhesion molecule expression, and B-cell migration, as well as reduced production of pro-inflammatory cytokines, such as IL-6 and TNF. Studies in patients treated with epratuzumab have revealed a number of pharmacodynamic effects that are linked to the mechanism of action (i.e., a loss of the target molecule CD22 from the B-cell surface followed by a modest reduction in peripheral B-cell numbers after prolonged therapy). Together, these data indicate that epratuzumab therapy affords a unique means to modulate BCR complex expression and signalling.
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Affiliation(s)
- Thomas Dörner
- Department of Medicine/Rheumatology and Clinical Immunology, Charité Berlin and DRFZ Berlin, 10117 Berlin, Germany.
| | - Anthony Shock
- UCB Pharma, 208 Bath Road, Slough, West Berkshire, SL1 3WE, UK.
| | | | - Peter E Lipsky
- Formerly National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA.
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12
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MAP Kinase Cascades in Antigen Receptor Signaling and Physiology. Curr Top Microbiol Immunol 2015; 393:211-231. [PMID: 26275875 DOI: 10.1007/82_2015_481] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) play roles in a cell type and context-dependent manner to convert extracellular stimuli to a variety of cellular responses, thereby directing cells to proliferation, differentiation, survival, apoptosis, and migration. Studies of genetically engineered mice or chemical inhibitors specific to each MAPK signaling pathway revealed that MAPKs have various, but non-redundant physiologically important roles among different families. MAPK cascades are obviously integrated in the B cell receptor signaling pathways as critical components to drive B cell-mediated immunity.
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13
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Zhang BC, Zhang J, Sun L. In-depth profiling and analysis of host and viral microRNAs in Japanese flounder (Paralichthys olivaceus) infected with megalocytivirus reveal involvement of microRNAs in host-virus interaction in teleost fish. BMC Genomics 2014; 15:878. [PMID: 25297525 PMCID: PMC4200114 DOI: 10.1186/1471-2164-15-878] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 09/24/2014] [Indexed: 01/21/2023] Open
Abstract
Background MicroRNAs (miRNAs) regulate gene expression by binding to mRNA transcripts in various biological processes. In mammals and birds, miRNAs are known to play vital parts in both host immune defense and viral infection. However, in lower vertebrates such as teleost, systematic investigations on host and viral miRNAs are lacking. Results In this study, we applied high-throughput sequencing technology to identify and analyze both host and viral miRNAs in Japanese flounder (Paralichthys olivaceus), an economically important teleost fish farmed widely in the world, infected with megalocytivirus at a timescale of 14 days divided into five different time points. The results showed that a total of 381 host miRNAs and 9 viral miRNAs were identified, the latter being all novel miRNAs that have no homologues in the currently available databases. Of the host miRNAs, 251 have been reported previously in flounder and other species, and 130 were discovered for the first time. The expression levels of 121 host miRNAs were significantly altered at 2 d to 14 d post-viral infection (pi), and these miRNAs were therefore classified as differentially expressed host miRNAs. The expression levels of all 9 viral miRNAs increased from 0 d pi to 10 d pi and then dropped from 10 d pi to 14 d pi. For the 121 differentially expressed host miRNAs and the 9 viral miRNAs, 243 and 48 putative target genes, respectively, were predicted in flounder. GO and KEGG enrichment analysis revealed that the putative target genes of both host and viral miRNAs were grouped mainly into the categories of immune response, signal transduction, and apoptotic process. Conclusions The results of our study provide the first evidences that indicate existence in teleost fish (i) infection-responsive host and viral miRNAs that exhibit dynamic changes in expression profiles during the course of viral infection, and (ii) potential involvement of miRNAs in host-viral interaction. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-878) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Li Sun
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
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14
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Kajihara R, Sakamoto H, Tanabe K, Takemoto K, Tasaki M, Ando Y, Inui S. Protein phosphatase 6 controls BCR-induced apoptosis of WEHI-231 cells by regulating ubiquitination of Bcl-xL. THE JOURNAL OF IMMUNOLOGY 2014; 192:5720-9. [PMID: 24808369 DOI: 10.4049/jimmunol.1302643] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Crosslinking BCR in the immature B cell line WEHI-231 causes apoptosis. We found that Bcl-xL was degraded by polyubiquitination upon BCR crosslinking and in this study explored the mechanism that controls the degradation of Bcl-xL. Ser(62) of Bcl-xL was phosphorylated by JNK to trigger polyubiquitination, and this was opposed by serine/threonine protein phosphatase 6 (PP6) that physically associated with Bcl-xL. We show BCR crosslinking decreased PP6 activity to allow Ser(62) phosphorylation of Bcl-xL. CD40 crosslinking rescues BCR-induced apoptosis, and we found PP6 associated with CD40 and PP6 activation in response to CD40. Our data suggest that PP6 activity is regulated to control apoptosis by modulating Ser(62) phosphorylation of Bcl-xL, which results in its polyubiquitination and degradation.
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Affiliation(s)
- Ryutaro Kajihara
- Department of Immunology and Hematology, Faculty of Life Sciences, Graduate School of Health Sciences, Kumamoto University, Kumamoto 862-0976, Japan; and
| | - Hitomi Sakamoto
- Department of Immunology and Hematology, Faculty of Life Sciences, Graduate School of Health Sciences, Kumamoto University, Kumamoto 862-0976, Japan; and
| | - Kano Tanabe
- Department of Immunology and Hematology, Faculty of Life Sciences, Graduate School of Health Sciences, Kumamoto University, Kumamoto 862-0976, Japan; and
| | - Kazuki Takemoto
- Department of Immunology and Hematology, Faculty of Life Sciences, Graduate School of Health Sciences, Kumamoto University, Kumamoto 862-0976, Japan; and
| | - Masayoshi Tasaki
- Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 862-0976, Japan
| | - Yukio Ando
- Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 862-0976, Japan
| | - Seiji Inui
- Department of Immunology and Hematology, Faculty of Life Sciences, Graduate School of Health Sciences, Kumamoto University, Kumamoto 862-0976, Japan; and
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15
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Activation of the B cell receptor leads to increased membrane proximity of the Igα cytoplasmic domain. PLoS One 2013; 8:e79148. [PMID: 24244439 PMCID: PMC3823606 DOI: 10.1371/journal.pone.0079148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 09/18/2013] [Indexed: 01/24/2023] Open
Abstract
Binding of antigen to the B cell receptor (BCR) induces conformational changes in BCR's cytoplasmic domains that are concomitant with phosphorylation of the immunoreceptor tyrosine-based activation motifs (ITAMs). Recently, reversible folding of the CD3ε and ξ chain ITAMs into the plasma membrane has been suggested to regulate T cell receptor signaling. Here we show that the Igα and Igβ cytoplasmic domains of the BCR do not associate with plasma membrane in resting B cells. However, antigen binding and ITAM phosphorylation specifically increased membrane proximity of Igα, but not Igβ. Thus, BCR activation is accompanied by asymmetric conformational changes, possibly promoting the binding of Igα and Igβ to differently localized signaling complexes.
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16
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Packard TA, Cambier JC. B lymphocyte antigen receptor signaling: initiation, amplification, and regulation. F1000PRIME REPORTS 2013; 5:40. [PMID: 24167721 PMCID: PMC3790562 DOI: 10.12703/p5-40] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
B lymphocytes and their differentiated daughters are charged with responding to the myriad pathogens in our environment and production of protective antibodies. A sample of the protective antibody produced by each clone is utilized as a component of the cell's antigen receptor (BCR). Transmembrane signals generated upon antigen binding to this receptor provide the primary directive for the cell's subsequent response. In this report, we discuss recent progress and current controversy regarding B cell receptor signal initiation, transduction and regulation.
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Affiliation(s)
- Thomas A. Packard
- Integrated Department of Immunology, University of Colorado School of Medicine & National Jewish Health1400 Jackson St, Denver, CO 80206
| | - John C. Cambier
- Integrated Department of Immunology, University of Colorado School of Medicine & National Jewish Health1400 Jackson St, Denver, CO 80206
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17
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Sun B, Mallampati S, Gong Y, Wang D, Lefebvre V, Sun X. Sox4 is required for the survival of pro-B cells. THE JOURNAL OF IMMUNOLOGY 2013; 190:2080-9. [PMID: 23345330 DOI: 10.4049/jimmunol.1202736] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The development of mature B cells from hematopoietic stem cells is a strictly orchestrated process involving multiple regulatory genes. The transcription factor Sox4 is required for this process, but its role has not been systematically studied, and the underlying mechanisms remain unknown. To determine when and how Sox4 functions in the stepwise process of B cell development, we used mice harboring conditional null alleles for Sox4 and a Cre transgene. Sox4 deletion in hematopoietic stem cells almost entirely eliminated pro-B cells in both fetal livers and adult bone marrow, resulting in a severe deficiency in later stage B cells, including circulating mature B cells. Sox4-deficient pro-B cells, particularly those expressing the stem cell factor receptor c-Kit, readily underwent apoptosis, and even more so when c-Kit activity was inhibited by imatinib. C-Kit-expressing pro-B cells showed decreased activation of the c-Kit downstream protein Src upon Sox4 deletion. Likewise, the level of the anti-apoptotic Bcl2 protein was decreased in residual pro-B cells, and its restoration using a Bcl2 transgene allowed not only partial rescue of pro-B cell survival but also B cell maturation in the absence of Sox4. Our findings indicate that Sox4 is required for the survival of pro-B cells and may functionally interact with c-Kit and Bcl2.
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Affiliation(s)
- Baohua Sun
- Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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18
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19
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Yang J, Reth M. The dissociation activation model of B cell antigen receptor triggering. FEBS Lett 2010; 584:4872-7. [PMID: 20920502 DOI: 10.1016/j.febslet.2010.09.045] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 09/27/2010] [Accepted: 09/27/2010] [Indexed: 11/19/2022]
Abstract
To detect its cognate antigen, each B lymphocyte contains up to 120000 B cell antigen receptor (BCR) complexes on its cell surface. How these abundant receptors remain silent on resting B cells and how they can be activated by a molecularly diverse set of ligands is poorly understood. The antigen-specific activation of the BCR is currently explained by the cross-linking model (CLM). This model predicts that the many BCR complexes on the surface of a B cell are dispersed signalling-inert monomers and that it is BCR dimerization that initiates signalling from the receptor. The finding that the BCR forms auto-inhibited oligomers on the surface of resting B cells falsifies these predictions of the CLM. We propose the dissociation activation model (DAM), which fits better with the existing body of experimental data.
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Affiliation(s)
- Jianying Yang
- Centre of Biological Signalling Studies BIOSS, University Freiburg, Freiburg, Germany
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20
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Sadri N, Lu JY, Badura ML, Schneider RJ. AUF1 is involved in splenic follicular B cell maintenance. BMC Immunol 2010; 11:1. [PMID: 20064252 PMCID: PMC2824733 DOI: 10.1186/1471-2172-11-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Accepted: 01/11/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The adenosine/uridine-rich element (ARE)-binding protein AUF1 functions to regulate the inflammatory response through the targeted degradation of cytokine and other mRNAs that contain specific AREs in their 3' noncoding region (3' NCR). To investigate the role of AUF1 in the immune system, we characterized the lymphoid compartments of AUF1-deficient mice. RESULTS Mice lacking AUF1 exhibit an altered proportion and size of splenic B cell subsets. We show prominent apoptosis in splenic B cell follicles and reduced expression of Bcl-2, A1, and Bcl-XL correlate with increased turnover and significant reduction in the number and proportion of splenic FO B cells in AUF1-deficient mice. In addition, AUF1-deficient mice exhibit a sharp decrease in splenic size and lymphocyte cellularity. Bone marrow transfer studies demonstrate that AUF1 deficiency induces cell-autonomous defects in mature B cell subsets but not in the overall number of splenocytes. Reconstitution of irradiated adult AUF1-deficient mice with wild-type bone marrow restores the proportion of FO and marginal zone (MZ) B cells, but does not rescue the decrease in the number of splenocytes. Functionally, AUF1-deficient mice mount an attenuated response to T cell-independent (TI) antigen, which correlates with impaired MZ B cell function. CONCLUSION These data indicate that AUF1 is important in the maintenance of splenic FO B cells and adequate humoral immune responses.
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Affiliation(s)
- Navid Sadri
- Department of Microbiology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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21
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Hoek KL, Carlesso G, Clark ES, Khan WN. Absence of mature peripheral B cell populations in mice with concomitant defects in B cell receptor and BAFF-R signaling. THE JOURNAL OF IMMUNOLOGY 2009; 183:5630-43. [PMID: 19843948 DOI: 10.4049/jimmunol.0901100] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Generation of mature B lymphocytes from early (T1) and late transitional (T2) precursors requires cooperative signaling through BCR and B cell-activating factor receptor 3 (BR3). Recent studies have shown that BCR signaling positively regulates NF-kappaB2, suggesting BCR regulation of BR3 signaling. To investigate the significance of signal integration from BCR and BR3 in B cell development and function, we crossed Btk-deficient mice (btk(-/-)), which are developmentally blocked between the T2 and the mature follicular B cell stage as a result of a partial defect in BCR signaling, and A/WySnJ mice, which possess a mutant BR3 defective in propagating intracellular signals that results in a severely reduced peripheral B cell compartment, although all B cell subsets are present in relatively normal ratios. A/WySnJ x btk(-/-) mice display a B cell-autonomous defect, resulting in a developmental block at an earlier stage (T1) than either mutation alone, leading to the loss of mature splenic follicular and marginal zone B cells, as well as the loss of peritoneal B1 and B2 cell populations. The competence of the double mutant T1 B cells to respond to TLR4 and CD40 survival and activation signals is further attenuated compared with single mutations as evidenced by severely reduced humoral immune responses in vivo and proliferation in response to anti-IgM, LPS, and anti-CD40 stimulation in vitro. Thus, BCR and BR3 independently and in concert regulate the survival, differentiation, and function of all B cell populations at and beyond T1, earliest transitional stage.
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Affiliation(s)
- Kristen L Hoek
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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22
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Abstract
Antigen receptors on the surface of B lymphocytes trigger adaptive immune responses after encountering their cognate antigens but also control a series of antigen-independent checkpoints during B cell development. These physiological processes are regulated by the expression and function of cell surface receptors, intracellular signaling molecules, and transcription factors. The function of these proteins can be altered by a dynamic array of post-translational modifications, using two interconnected mechanisms. These modifications can directly induce an altered conformational state in the protein target of the modification itself. In addition, they can create new binding sites for other protein partners, thereby contributing to where and when such multiple protein assemblies are activated within cells. As a new type of post-transcriptional regulator, microRNAs have emerged to influence the development and function of B cells by affecting the expression of target mRNAs.
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23
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Price PW, McKinney EC, Wang Y, Sasser LE, Kandasamy MK, Matsuuchi L, Milcarek C, Deal RB, Culver DG, Meagher RB. Engineered cell surface expression of membrane immunoglobulin as a means to identify monoclonal antibody-secreting hybridomas. J Immunol Methods 2009; 343:28-41. [PMID: 19187782 DOI: 10.1016/j.jim.2009.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 01/11/2009] [Accepted: 01/13/2009] [Indexed: 11/26/2022]
Abstract
Monoclonal antibodies (mAbs) have proven to be effective biological reagents in the form of therapeutic drugs and diagnostics for many pathologies, as well as valuable research tools. Existing methods for isolating mAb-producing hybridomas are tedious and time consuming. Herein we describe a novel system in which mAb-secreting hybridoma cells were induced to co-express significant amounts of the membrane form of the secreted immunoglobulin (Ig) on their surfaces and are efficiently recovered by fluorescent activated cell sorting (FACS). Fusion of a novel myeloma parent, SP2ab, expressing transgenic Igalpha and Igbeta of the B-cell receptor complex (BCR) with spleen cells resulted in hybridomas demonstrating order of magnitude increases in BCR surface expression. Surface Ig levels correlated with transgenic Igalpha expression, and these cells also secreted normal levels of mAb. Hundreds of hybridoma lines producing mAbs specific for a variety of antigens were rapidly isolated as single cell-derived clones after FACS. Significant improvements using the Direct Selection of Hybridomas (DiSH) by FACS include reduced time and labor, improved capability of isolating positive hybridomas, and the ease of manipulating cloned cell lines relative to previously existing approaches that require Limiting Dilution Subcloning (LDS).
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24
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Zhang XK, Moussa O, LaRue A, Bradshaw S, Molano I, Spyropoulos DD, Gilkeson GS, Watson DK. The transcription factor Fli-1 modulates marginal zone and follicular B cell development in mice. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2008; 181:1644-54. [PMID: 18641300 PMCID: PMC2504761 DOI: 10.4049/jimmunol.181.3.1644] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Fli-1 belongs to the Ets transcription factor family and is expressed primarily in hematopoietic cells, including most cells active in immunity. To assess the role of Fli-1 in lymphocyte development in vivo, we generated mice that express a truncated Fli-1 protein, lacking the C-terminal transcriptional activation domain (Fli-1(DeltaCTA)). Fli-1(DeltaCTA)/Fli-1(DeltaCTA) mice had significantly fewer splenic follicular B cells, and an increased number of transitional and marginal zone B cells, compared with wild-type controls. Bone marrow reconstitution studies demonstrated that this phenotype is the result of lymphocyte intrinsic effects. Expression of Igalpha and other genes implicated in B cell development, including Pax-5, E2A, and Egr-1, are reduced, while Id1 and Id2 are increased in Fli-1(DeltaCTA)/Fli-1(DeltaCTA) mice. Proliferation of B cells from Fli-1(DeltaCTA)/Fli-1(DeltaCTA) mice was diminished, although intracellular Ca(2+) flux in B cells from Fli-1(DeltaCTA)/Fli-1(DeltaCTA) mice was similar to that of wild-type controls after anti-IgM stimulation. Immune responses and in vitro class switch recombination were also altered in Fli-1(DeltaCTA)/Fli-1(DeltaCTA) mice. Thus, Fli-1 modulates B cell development both centrally and peripherally, resulting in a significant impact on the in vivo immune response.
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Affiliation(s)
- Xian K Zhang
- Division of Rheumatology and Immunology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA.
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25
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Erk kinases link pre-B cell receptor signaling to transcriptional events required for early B cell expansion. Immunity 2008; 28:499-508. [PMID: 18356083 DOI: 10.1016/j.immuni.2008.02.015] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 02/06/2008] [Accepted: 02/06/2008] [Indexed: 11/23/2022]
Abstract
The pre-B cell receptor (pre-BCR) plays a crucial role in the development of immature B cells. Although certain aspects of proximal pre-BCR signaling have been studied, the intermediate signal transducers and the distal transcription modulators are poorly characterized. Here, we demonstrate that deletion of both Erk1 and Erk2 kinases was associated with defective pre-BCR-mediated cell expansion as well as a block in the transition of pro-B to pre-B cells. Phosphorylation of transcription factors Elk1 and CREB was mediated by Erk, and a dominant-negative mutation in the Erk-mediated phosphorylation sites of Elk1 or CREB suppressed pre-BCR-mediated cell expansion as well as expression of genes including Myc, which is involved in the cell-cycle progression. Together, our results identify a crucial role for Erk kinases in regulating B cell development by initiating transcriptional regulatory network and thereby pre-BCR-mediated cell expansion.
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26
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Abstract
In B lymphocytes, the B-cell adaptor for phosphatidylinositol 3-kinase (BCAP) facilitates signaling from the antigen receptor. Mice lacking BCAP have a predominantly immature pool of B cells with impaired immune function and increased susceptibility to apoptosis. Unexpectedly, we have found that natural killer (NK) cells from BCAP-deficient mice are more mature, more long-lived, more resistant to apoptosis, and exhibit enhanced functional activity compared with NK cells from wild-type mice. Surprisingly, these effects are evident despite a severe impairment of the immunoreceptor tyrosine-based activation motif-mediated Akt signaling pathway. The seemingly paradoxical phenotype reveals inherent differences in the signals controlling the final maturation of B cells and NK cells, which depend on positive and negative signals, respectively. Both enhanced interferon-gamma responses and augmented maturation of NK cells in BCAP-deficient mice are independent of available MHC class I ligands. Our data support a model in which blunting of BCAP-mediated activation signaling in developing NK cells promotes functionality, terminal maturation, and long-term survival.
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27
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Geraldes P, Rebrovich M, Herrmann K, Wong J, Jäck HM, Wabl M, Cascalho M. Ig Heavy Chain Promotes Mature B Cell Survival in the Absence of Light Chain. THE JOURNAL OF IMMUNOLOGY 2007; 179:1659-68. [PMID: 17641032 DOI: 10.4049/jimmunol.179.3.1659] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Survival of mature B cells is thought to depend on the BCR signaling (BCR) because ablation of either H chain (HC) expression or BCR signaling causes B cells to rapidly disappear. Whether a complete BCR is required for survival of mature B cells is not known. To address this question, we generated a mouse in which we can repress the expression of a transgenic Ig L chain (IgL) by doxycycline (IgL-repressible mouse). Repression of IgL abrogated expression. Surprisingly, however, IgL-negative B cells survived longer than 14 wk, expressed signal-competent HC on the cell's surface, and active unfolded protein response factors. Like postgerminal center B cells, IgL-negative B cells were small lymphocytes, not dividing and expressed Bcl-6. Our results indicate that expression of unpaired HC, as it may occur as a consequence of Ag ligation, somatic hypermutation, or receptor editing, facilitates the survival of cells either by inducing receptor signaling or by inducing unfolded protein response and/or the expression of survival genes such as Bcl-6.
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Affiliation(s)
- Pedro Geraldes
- Transplantation Biology Program, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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28
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Xue HH, Bollenbacher-Reilley J, Wu Z, Spolski R, Jing X, Zhang YC, McCoy JP, Leonard WJ. The transcription factor GABP is a critical regulator of B lymphocyte development. Immunity 2007; 26:421-31. [PMID: 17442597 DOI: 10.1016/j.immuni.2007.03.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Revised: 01/09/2007] [Accepted: 03/16/2007] [Indexed: 12/19/2022]
Abstract
GA binding protein (GABP) is a ubiquitously expressed Ets-family transcription factor that critically regulates the expression of the interleukin-7 receptor alpha chain (IL-7Ralpha) in T cells, whereas it is dispensable for IL-7Ralpha expression in fetal liver B cells. Here we showed that deficiency of GABPalpha, the DNA-binding subunit of GABP, resulted in profoundly defective B cell development and a compromised humoral immune response, in addition to thymic developmental defects. Furthermore, the expression of Pax5 and Pax5 target genes such as Cd79a was greatly diminished in GABPalpha-deficient B cell progenitors, pro-B, and mature B cells. GABP could bind to the regulatory regions of Pax5 and Cd79a in vivo. Thus, GABP is a key regulator of B cell development, maturation, and function.
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Affiliation(s)
- Hai-Hui Xue
- Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1674, USA
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29
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Twohig J, Kulik L, Haluszczak C, Reuter J, Rossbach A, Bull M, Holers VM, Marchbank KJ. Defective B cell ontogeny and immune response in human complement receptor 2 (CR2, CD21) transgenic mice is partially recovered in the absence of C3. Mol Immunol 2007; 44:3434-44. [PMID: 17379312 PMCID: PMC1948027 DOI: 10.1016/j.molimm.2007.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 02/12/2007] [Accepted: 02/14/2007] [Indexed: 01/13/2023]
Abstract
Mice prematurely expressing human CR2 (hCR2) in the B cell lineage have a defective B cell ontogeny and immune response. Our recent analysis of this phenotype suggested that signaling through hCR2 and presumably mouse CD19 on the B cell surface, during bone marrow development, could result in the observed changes in B cell function in these mice. To test this hypothesis, we back crossed hCR2(high) transgenic mice onto the CD19(-/-) background. CD19(-/-)hCR2(high) mice were found to possess even fewer mature B cells than their CD19(+/+)hCR2(high) littermates, demonstrating that loss of CD19 exacerbated the effects elicited through hCR2. This data suggests that CD19 provides a survival signal during B cell development in this model. Next, we examined if the removal of the main ligand for CR2, namely C3d, through back-crossing onto the C3(-/-) background could restore normal B cell development. However, we found only minor recovery in peripheral B cell numbers and no obvious change in function. This was despite a three-fold increase in the level of hCR2 expression on B cells isolated from the spleen or bone marrow of C3(-/-)hCR2(high) mice when compared with C3 sufficient littermates. These data demonstrate that hCR2 is integrated in mouse B cell signaling and that the downstream effects of hCR2 expression during early B cell development are partially but not completely due to interaction with C3 fragments and signaling through CD19 in the bone marrow environment.
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Affiliation(s)
- Jason Twohig
- Department of Medical Biochemistry & Immunology, Cardiff University, Heath Park, Cardiff CF14 4XX, UK
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30
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Song H, Zhang J, Chiang YJ, Siraganian RP, Hodes RJ. Redundancy in B Cell Developmental Pathways: c-Cbl Inactivation Rescues Early B Cell Development through a B Cell Linker Protein-Independent Pathway. THE JOURNAL OF IMMUNOLOGY 2007; 178:926-35. [PMID: 17202354 DOI: 10.4049/jimmunol.178.2.926] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Deficiency in the adaptor protein B cell linker protein (BLNK) results in a substantial but incomplete block in B cell development, suggesting that alternative pathways exist for B lineage differentiation. Another adaptor protein, c-Cbl, plays a negative regulatory role in several BCR-signaling pathways. We therefore investigated the role of c-Cbl during B cell development and addressed the possibility that redundancies in pathways for B cell differentiation could be further revealed by eliminating negative effects mediated by c-Cbl. Strikingly, c-Cbl inactivation reversed a number of the critical defects in early B cell differentiation that are seen in BLNK-deficient mice. c-Cbl(-/-)BLNK(-/-) mice exhibited normalized down-regulation of pre-BCR and CD43, up-regulation of MHC class II, and augmented L chain rearrangement, resulting in a successful transition from pre-B cells to immature B cells. c-Cbl inactivation also reversed the potentially tumor-predisposing hyperproliferative response of BLNK(-/-) pre-B cells to IL-7. Pre-BCR cross-linking induced enhanced and prolonged tyrosine phosphorylation in c-Cbl(-/-)BLNK(-/-) pre-BCR(+) pre-B cells compared with c-Cbl(+/-)BLNK(-/-) cells, including elevated phosphorylation of Lyn, Syk, Btk, and phospholipase C-gamma2. Our studies suggest that some, but not all, pre-BCR-triggered developmental events can be mediated by BLNK-independent pathways that are negatively regulated by c-Cbl, and further suggest that different events during early B cell development require different strength or duration of pre-BCR signaling.
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Affiliation(s)
- Haifeng Song
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
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31
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Vettermann C, Lutz J, Selg M, Bösl M, Jäck HM. Genomic suppression of murine B29/Ig-β promoter-driven transgenes. Eur J Immunol 2006; 36:3324-33. [PMID: 17111355 DOI: 10.1002/eji.200636536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Immunoglobulin beta (Ig-beta) is a critical signal transducer of precursor B cell and B cell receptors. B29, the gene coding for Ig-beta, is switched on in progenitor B cells and expressed until the terminal stage of antibody-producing plasma cells. Although several cis-acting elements and transcription factors required for B29 expression have been characterized in cell lines, the in vivo significance of individual motifs located in the 1.2-kb promoter region remained unclear. To address whether this region drives B lineage-specific expression in mice as efficiently as in transfected cell lines, we established transgenic animals carrying the B29 promoter fused to either enhanced green fluorescent protein (EGFP) or the precursor B cell receptor component lambda5. Surprisingly, only minimal levels of B29-derived transcripts were produced in B lymphoid tissues of several independent transgenic lines, and the respective proteins were below the detection limit. In addition, transgenic transcripts were found in testis, kidney and brain. Hence, the 1.2-kb-sized B29 promoter does not define a strong, B lineage-restricted expression unit when randomly integrated into the genome and passed through the murine germ line. Therefore, yet unidentified genomic locus control elements are required to efficiently drive B29 expression in B lymphocytes.
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Affiliation(s)
- Christian Vettermann
- Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger-Center for Molecular Medicine, University of Erlangen-Nürnberg, Erlangen, Germany
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32
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Fuentes-Pananá EM, Bannish G, Karnell FG, Treml JF, Monroe JG. Analysis of the Individual Contributions of Igα (CD79a)- and Igβ (CD79b)-Mediated Tonic Signaling for Bone Marrow B Cell Development and Peripheral B Cell Maturation. THE JOURNAL OF IMMUNOLOGY 2006; 177:7913-22. [PMID: 17114463 DOI: 10.4049/jimmunol.177.11.7913] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The individual contribution of Igalpha and Igbeta for BCR-triggered fates is unclear. Prior evidence supports conflicting ideas concerning unique as well as redundant functions for these proteins in the context of BCR/pre-BCR signaling. Part of this ambiguity may reflect the recent appreciation that Igalpha and Igbeta participate in both Ag-independent (tonic) and Ag-dependent signaling. The present study undertook defining the individual requirement for Igalpha and Igbeta under conditions where only ligand-independent tonic signaling was operative. In this regard, we have constructed chimeric proteins containing one or two copies of the cytoplasmic domains of either Igalpha or Igbeta and Igalpha/Igbeta heterodimers with targeted Tyr-->Phe modifications. The ability of these proteins to act as surrogate receptors and trigger early bone marrow and peripheral B cell maturation was tested in RAG2(-/-) primary pro-B cell lines and in gene transfer experiments in the muMT mouse model. We considered that the threshold for a functional activity mediated by the pre-BCR/BCR might only be reached when two functional copies of the Igalpha/Igbeta ITAM domain are expressed together, and therefore the specificity conferred by these proteins can only be observed in these conditions. We found that the ligand-independent tonic signal is sufficient to drive development into mature follicular B cells and both Igalpha and Igbeta chains supported formation of this population. In contrast, neither marginal zone nor B1 mature B cell subsets develop from bone marrow precursors under conditions where only tonic signals are generated.
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Affiliation(s)
- Ezequiel M Fuentes-Pananá
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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33
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McCandless EE, Wang Q, Woerner BM, Harper JM, Klein RS. CXCL12 Limits Inflammation by Localizing Mononuclear Infiltrates to the Perivascular Space during Experimental Autoimmune Encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2006; 177:8053-64. [PMID: 17114479 DOI: 10.4049/jimmunol.177.11.8053] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The inflammatory response in the CNS begins with the movement of leukocytes across the blood-brain barrier in a multistep process that requires cells to pass through a perivascular space before entering the parenchyma. The molecular mechanisms that orchestrate this movement are not known. The chemokine CXCL12 is highly expressed throughout the CNS by microendothelial cells under normal conditions, suggesting it might play a role maintaining the blood-brain barrier. We tested this hypothesis in the setting of experimental autoimmune encephalomyelitis (EAE) by using AMD3100, a specific antagonist of the CXCL12 receptor CXCR4. We demonstrate that the loss of CXCR4 activation enhances the migration of infiltrating leukocytes into the CNS parenchyma. CXCL12 is expressed at the basolateral surface of CNS endothelial cells in normal spinal cord and at the onset of EAE. This polarity is lost in vessels associated with an extensive parenchymal invasion of mononuclear cells during the peak of disease. Inhibition of CXCR4 activation during the induction of EAE leads to loss of the typical intense perivascular cuffs, which are replaced with widespread white matter infiltration of mononuclear cells, worsening the clinical severity of the disease and increasing inflammation. Taken together, these data suggest a novel anti-inflammatory role for CXCL12 during EAE in that it functions to localize CXCR4-expressing mononuclear cells to the perivascular space, thereby limiting the parenchymal infiltration of autoreactive effector cells.
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MESH Headings
- Animals
- Blood-Brain Barrier/immunology
- Blood-Brain Barrier/metabolism
- Brain/blood supply
- Brain/immunology
- Brain/pathology
- Capillary Permeability/immunology
- Chemokine CXCL12
- Chemokines, CXC/immunology
- Chemokines, CXC/metabolism
- Chemotaxis, Leukocyte/immunology
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Endothelial Cells/immunology
- Endothelial Cells/metabolism
- Female
- Flow Cytometry
- Immunohistochemistry
- Inflammation/immunology
- Leukocytes, Mononuclear/immunology
- Mice
- Mice, Inbred C57BL
- Receptors, CXCR4/immunology
- Receptors, CXCR4/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Spinal Cord/blood supply
- Spinal Cord/immunology
- Spinal Cord/pathology
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Affiliation(s)
- Erin E McCandless
- Division of Infectious Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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34
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Kanamaru Y, Tamouza H, Pfirsch S, El-Mehdi D, Guérin-Marchand C, Pretolani M, Blank U, Monteiro RC. IgA Fc receptor I signals apoptosis through the FcRγ ITAM and affects tumor growth. Blood 2006; 109:203-11. [PMID: 16990604 DOI: 10.1182/blood-2006-06-025882] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Abstract
The IgA Fc receptor (FcαRI) has dual proinflammatory and anti-inflammatory functions that are transmitted through the immunoreceptor tyrosine-based activation motifs (ITAMs) of the associated FcRγ subunit. Whereas the involvement of FcαRI in inflammation is well documented, little is known of its anti-inflammatory mechanisms. Here we show that monomeric targeting of FcαRI by anti-FcαRI Fab or serum IgA triggers apoptosis in human monocytes, monocytic cell lines, and FcαRI+ transfectants. However, the physiologic ligand IgA induced apoptosis only when cells were cultured in low serum conditions, indicating differences with induction of anti-inflammatory signaling. Apoptosis signaling required the FcRγ ITAM, as cells transfected with FcαRI or with a chimeric FcαRI-FcRγ responded to death-activating signals, whereas cells expressing a mutated FcαRIR209L unable to associate with FcRγ, or an ITAM-mutated chimeric FcαRI-FcRγ, did not respond. FcαRI-mediated apoptosis signals were blocked by treatment with the pan-caspase inhibitor zVAD-fmk, involved proteolysis of procaspase-3, and correlated negatively with SHP-1 concentration. Anti-FcαRI Fab treatment of nude mice injected subcutaneously with FcαRI+ mast-cell transfectants prevented tumor development and halted the growth of established tumors. These findings demonstrate that, on monomeric targeting, FcαRI functions as an FcRγ ITAM-dependent apoptotic module that may be fundamental for controlling inflammation and tumor growth.
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MESH Headings
- Amino Acid Chloromethyl Ketones/pharmacology
- Amino Acid Motifs
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/physiology
- Apoptosis/physiology
- Caspase 3/metabolism
- Cell Line, Tumor
- Cells, Cultured
- Culture Media, Serum-Free
- Cysteine Proteinase Inhibitors/pharmacology
- Enzyme Activation
- Female
- Humans
- Immunoglobulin A/immunology
- Immunoglobulin Fab Fragments/pharmacology
- Inflammation/immunology
- Inflammation/pathology
- Leukemia, Basophilic, Acute/pathology
- Leukemia, Basophilic, Acute/therapy
- Mast Cells/physiology
- Mast Cells/transplantation
- Mice
- Mice, Inbred C57BL
- Mice, Nude
- Mice, Transgenic
- Neoplasms/pathology
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/antagonists & inhibitors
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/genetics
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/physiology
- RNA, Small Interfering/pharmacology
- Rats
- Receptors, Fc/chemistry
- Receptors, Fc/genetics
- Receptors, Fc/physiology
- Receptors, IgG/physiology
- Recombinant Fusion Proteins/physiology
- Skin Transplantation
- Transfection
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Affiliation(s)
- Yutaka Kanamaru
- Institut National de la Santé et de la Recherche Médicale (INSERM) U699, Paris, France
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35
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Bossen C, Schneider P. BAFF, APRIL and their receptors: structure, function and signaling. Semin Immunol 2006; 18:263-75. [PMID: 16914324 DOI: 10.1016/j.smim.2006.04.006] [Citation(s) in RCA: 359] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 04/03/2006] [Indexed: 12/17/2022]
Abstract
BAFF, APRIL and their receptors play important immunological roles, especially in the B cell arm of the immune system. A number of splice isoforms have been described for both ligands and receptors in this subfamily, some of which are conserved between mouse and human, while others are species-specific. Structural and mutational analyses have revealed key determinants of receptor-ligand specificity. BAFF-R has a strong selectivity for BAFF; BCMA has a higher affinity for APRIL than for BAFF, while TACI binds both ligands equally well. The molecular signaling events downstream of BAFF-R, BCMA and TACI are still incompletely characterized. Survival appears to be mediated by upregulation of Bcl-2 family members through NF-kappaB activation, degradation of the pro-apototic Bim protein, and control of subcellular localization of PCKdelta. Very little is known about other signaling events associated with receptor engagement by BAFF and APRIL that lead for example to B cell activation or to CD40L-independent Ig switch.
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Affiliation(s)
- Claudia Bossen
- Biochemistry Department, University of Lausanne, Boveresses 155, CH-1066 Epalinges, Switzerland
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36
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Gazumyan A, Reichlin A, Nussenzweig MC. Ig beta tyrosine residues contribute to the control of B cell receptor signaling by regulating receptor internalization. J Exp Med 2006; 203:1785-94. [PMID: 16818674 PMCID: PMC2118343 DOI: 10.1084/jem.20060221] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Accepted: 06/02/2006] [Indexed: 12/14/2022] Open
Abstract
Immunoglobulin (Ig)alpha and Igbeta initiate B cell receptor (BCR) signaling through immune receptor tyrosine activation motifs (ITAMs) that are targets of SH2 domain-containing kinases. To examine the function of Igbeta ITAM tyrosine resides in mature B cells in vivo, we exchanged these residues for alanine by gene targeting (Igbeta(AA)). Mutant mice showed normal development of all B cell subtypes with the exception of B1 cells that were reduced by fivefold. However, primary B cells purified from Igbeta(AA) mice showed significantly decreased steady-state and ligand-mediated BCR internalization and higher levels of cell surface IgM and IgD. BCR cross-linking resulted in decreased Src and Syk activation but paradoxically enhanced and prolonged BCR signaling, as measured by cellular tyrosine phosphorylation, Ca(++) flux, AKT, and ERK activation. In addition, B cells with the ITAM mutant receptor showed an enhanced response to a T-independent antigen. Thus, Igbeta ITAM tyrosines help set BCR signaling threshold by regulating receptor internalization.
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Affiliation(s)
- Anna Gazumyan
- Laboratory of Molecular Immunology and 2Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA.
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37
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Hu H, Wang B, Borde M, Nardone J, Maika S, Allred L, Tucker PW, Rao A. Foxp1 is an essential transcriptional regulator of B cell development. Nat Immunol 2006; 7:819-26. [PMID: 16819554 DOI: 10.1038/ni1358] [Citation(s) in RCA: 249] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 05/24/2006] [Indexed: 01/08/2023]
Abstract
Forkhead transcription factors are key participants in development and immune regulation. Here we demonstrate that absence of the gene encoding the forkhead transcription factor Foxp1 resulted in a profound defect in early B cell development. Foxp1 deficiency was associated with decreased expression of all B lineage genes in B220+ fetal liver cells as well as with a block in the transition from pro-B cell to pre-B cell involving diminished expression of recombination-activating genes 1 and 2. Foxp1 bound to the Erag enhancer and was involved in controlling variable-(diversity)-joining recombination of the gene encoding immunoglobulin heavy chain in a B cell lineage-specific way. Our results identify Foxp1 as an essential participant in the transcriptional regulatory network of B lymphopoiesis.
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Affiliation(s)
- Hui Hu
- Department of Pathology, Harvard Medical School, CBR Institute for Biomedical Research, Boston, Massachusetts 02115, USA.
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38
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Mehr R. Feedback Loops, Reversals and Nonlinearities in Lymphocyte Development. Bull Math Biol 2006; 68:1073-94. [PMID: 16794916 DOI: 10.1007/s11538-006-9124-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Accepted: 02/13/2006] [Indexed: 02/06/2023]
Abstract
Systems of differentiating cells are often regarded by experimental biologists as unidirectional processes, in which cells spend a fixed time at each successive developmental stage. However, mathematical modeling has in several cases revealed that differentiating cell systems are more complex than previously believed. For example, non-linear transitions, feedback effects, and even apparent reversals have been suggested by our studies on models for the development of lymphocytes and their receptor repertoires, and are reviewed in this paper. These studies have shown that cell population growth in developing lymphocyte subsets is usually nonlinear, as it depends on the density of cells in each compartment. Additionally, T cell development has been shown to be subject to feedback regulation by mature T cell subsets, and B cell development has been shown to include a phenotypic reflux from an advanced to an earlier developmental stage. The challenges we face in our efforts to understand how the repertoires of these cells are generated and regulated are also discussed here.
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Affiliation(s)
- Ramit Mehr
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel.
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39
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Espeli M, Rossi B, Mancini SJC, Roche P, Gauthier L, Schiff C. Initiation of pre-B cell receptor signaling: Common and distinctive features in human and mouse. Semin Immunol 2006; 18:56-66. [PMID: 16337808 DOI: 10.1016/j.smim.2005.11.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
B cell development in the bone marrow is a highly regulated process and expression of a functional pre-BCR represents a crucial checkpoint, common to human and mouse. In this review, we discuss pre-BCR analogies and differences between the two species leading to pre-B cell differentiation and proliferation. In addition, the mechanisms triggering pre-BCR activation are reviewed, taking into account the recent report of heparan sulfates and galectin 1 as stromal cell-derived pre-BCR ligands. Finally, ligand-induced pre-BCR activation models are proposed on the bases of the differences reported for pre-BCR and IL7 dependencies in the two species.
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Affiliation(s)
- Marion Espeli
- Centre d'Immunologie de Marseille-Luminy (CIML), CNRS-INSERM-University Méditerranée, Campus de Luminy, Case 906, 13288 Marseille Cedex 09, France
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40
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Vettermann C, Herrmann K, Jäck HM. Powered by pairing: The surrogate light chain amplifies immunoglobulin heavy chain signaling and pre-selects the antibody repertoire. Semin Immunol 2006; 18:44-55. [PMID: 16464608 DOI: 10.1016/j.smim.2006.01.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Selective expansion of functional pre-B cells is accomplished by the assembly of a signaling-competent pre-B cell receptor (pre-BCR) consisting of immunoglobulin mu heavy chains (muHC), surrogate light chains (SLC) and Igalpha/Igbeta. Here, we review recent data showing that muHCs, in the absence of SLC, deliver autonomous differentiation signals. However, enhanced signaling necessary for pre-B cell expansion requires cross-linking of pre-BCRs via the non-immunoglobulin tail of SLC's subunit lambda5. We also discuss how SLC's ability to modulate the strength of pre-BCR signals is controlled by a muHC's idiotype and its affinity to the chaperone BiP. In this model, BiP in concert with SLC functions as a pre-selector of the antibody repertoire.
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Affiliation(s)
- Christian Vettermann
- Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger-Center for Molecular Medicine, Friedrich-Alexander-University Erlangen-Nürnberg, D-91054 Erlangen, Germany
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41
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Abstract
Progenitor B lymphocytes that successfully assemble a heavy chain gene encoding an immunoglobulin capable of pairing with surrogate light chain proteins trigger their own further differentiation by signaling via the pre-BCR complex. The pre-BCR signals several rounds of proliferation and, in this expanded population, directs a complex, B cell-specific set of epigenetic changes resulting in allelic exclusion of the heavy chain locus and activation of the light chain loci for V(D)J recombination.
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Affiliation(s)
- Jamie K Geier
- UC-Berkeley, Department of Molecular & Cell Biology, Division of Immunology, 439 Life Sciences Addition, Berkeley, CA 94720-3200, USA
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42
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Dragone LL, Myers MD, White C, Sosinowski T, Weiss A. Src-Like Adaptor Protein Regulates B Cell Development and Function. THE JOURNAL OF IMMUNOLOGY 2005; 176:335-45. [PMID: 16365426 DOI: 10.4049/jimmunol.176.1.335] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The avidity of BCRs and TCRs influences signal strength during processes of lymphocyte development. Avidity is determined by both the intrinsic affinity for Ag and surface levels of the Ag receptor. The Src-like adaptor protein (SLAP) is a regulator of TCR levels on thymocytes, and its deficiency alters thymocyte development. We hypothesized that SLAP, which is expressed in B cells, also is important in regulating BCR levels, signal strength, and B cell development. To test this hypothesis, we analyzed the B cell compartment in SLAP-deficient mice. We found increased splenic B cell numbers and decreased surface IgM levels on mature, splenic B cells deficient in SLAP. Immature bone marrow and splenic B cells from BCR-transgenic, SLAP-deficient mice were found to express higher surface levels of IgM. In contrast, mature splenic B cells from BCR-transgenic mice expressed decreased levels of surface BCR associated with decreased calcium flux and activation-induced markers, compared with controls. These data suggest that SLAP regulates BCR levels and signal strength during lymphocyte development.
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Affiliation(s)
- Leonard L Dragone
- Division of Pediatric Immunology/Rheumatology, Department of Pediatrics, University of California, San Francisco, CA 94143, USA
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43
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Wen L, Brill-Dashoff J, Shinton SA, Asano M, Hardy RR, Hayakawa K. Evidence of marginal-zone B cell-positive selection in spleen. Immunity 2005; 23:297-308. [PMID: 16169502 DOI: 10.1016/j.immuni.2005.08.007] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2005] [Revised: 08/12/2005] [Accepted: 08/17/2005] [Indexed: 10/25/2022]
Abstract
Antigen receptor-mediated signaling is critical for the development and survival of B cells. However, it has not been established whether B cell development requires a signal from self-ligand engagement at the immature stage, a process known as "positive selection." Here, using a monoclonal B cell receptor (BCR) mouse line, specific for the self-Thy-1/CD90 glycoprotein, we demonstrate that BCR crosslinking by low-dose self-antigen promotes survival of immature B cells in culture. In spleen, an increase in BCR signaling strength, induced by low-dose self-antigen, directed naive immature B cells to mature, not into the default follicular B cell fate, but instead into the marginal-zone B cell subset. These data indicate that positive selection can occur in developing B cells and that BCR signal strength is a key factor in deciding between two functionally distinct mature B cell compartments in the microenvironment of the spleen.
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Affiliation(s)
- Lijun Wen
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
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44
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Abstract
A plethora of genes involved in murine B and T cell development have been identified, and developmental pathways within the primary lymphoid tissues have been well delineated. The generation of a functional, but non-self reacting lymphocyte repertoire results from the completion of several checkpoints during lymphocyte development and competition for survival factors in the periphery. Improved knowledge of these developmental checkpoints and homeostatic mechanisms is critical for understanding human immunodeficiency, leukaemia/lymphoma and autoimmunity, which are conditions where checkpoints and homeostasis are likely to be deregulated.
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Affiliation(s)
- Lisa A Miosge
- Immunogenomics Laboratory, Division of Immunology and Genetics, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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45
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Grimaldi CM, Hicks R, Diamond B. B Cell Selection and Susceptibility to Autoimmunity. THE JOURNAL OF IMMUNOLOGY 2005; 174:1775-81. [PMID: 15699102 DOI: 10.4049/jimmunol.174.4.1775] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Autoreactive B cells arise routinely as part of the naive B cell repertoire. The immune system employs several mechanisms in an attempt to silence these autoreactive cells before they achieve immunocompetence. The BCR plays a central role in B cell development, activation, survival, and apoptosis, and thus is a critical component of the regulation of both protective and autoreactive B cells. The strength of signal mediated by the BCR is determined by numerous factors, both B cell intrinsic and B cell extrinsic. Perturbations in the molecules that regulate the BCR signal strength or that activate pathways that engage in cross talk with the BCR-mediated signaling pathways can lead to the aberrant survival and activation of autoreactive B cells. In this review, we will discuss the some newly identified genetic loci and factors that modulate the BCR signal transduction pathway and, therefore, the regulation of autoreactive B cells. We will also provide evidence for a model of autoreactivity in which a reduction in the strength of the BCR signal allows the survival and the modulation of a naive B cell repertoire replete with autoreactivity.
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46
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Pike KA, Ratcliffe MJH. Dual Requirement for the Igα Immunoreceptor Tyrosine-Based Activation Motif (ITAM) and a Conserved Non-Igα ITAM Tyrosine in Supporting Igαβ-Mediated B Cell Development. THE JOURNAL OF IMMUNOLOGY 2005; 174:2012-20. [PMID: 15699130 DOI: 10.4049/jimmunol.174.4.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Surface Ig (sIg) expression is a critical checkpoint during avian B cell development. Only cells that express sIg colonize bursal follicles, clonally expand, and undergo Ig diversification by gene conversion. Expression of a heterodimer, in which the extracellular and transmembrane domains of murine CD8alpha or CD8beta are fused to the cytoplasmic domains of chicken Igalpha (chIgalpha) or Igbeta, respectively (murine CD8alpha (mCD8alpha):chIgalpha + mCD8beta:chIgbeta), or an mCD8alpha:chIgalpha homodimer supported bursal B cell development as efficiently as endogenous sIg. In this study we demonstrate that B cell development, in the absence of chIgbeta, requires both the Igalpha ITAM and a conserved non-ITAM Igalpha tyrosine (Y3) that has been associated with binding to B cell linker protein (BLNK). When associated with the cytoplasmic domain of Igbeta, the Igalpha ITAM is not required for the induction of strong calcium mobilization or BLNK phosphorylation, but is still necessary to support B cell development. In contrast, mutation of the Igalpha Y3 severely compromised calcium mobilization when expressed as either a homodimer or a heterodimer with the cytoplasmic domain of Igbeta. However, coexpression of the cytoplasmic domain of Igbeta partially complemented the Igalpha Y3 mutation, rescuing higher levels of BLNK phosphorylation and, more strikingly, supporting B cell development.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Amino Acid Motifs
- Animals
- Antigens, CD/genetics
- Antigens, CD/physiology
- Avian Sarcoma Viruses/genetics
- Avian Sarcoma Viruses/immunology
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- CD79 Antigens
- Calcium Signaling/genetics
- Calcium Signaling/immunology
- Carrier Proteins/metabolism
- Cell Differentiation/immunology
- Cell Line, Tumor
- Cells, Cultured
- Chick Embryo
- Chickens
- Conserved Sequence
- Cytoplasm/immunology
- Cytoplasm/metabolism
- Dimerization
- Mice
- Mutagenesis, Site-Directed
- Phosphoproteins/metabolism
- Phosphorylation
- Protein Structure, Tertiary/genetics
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/physiology
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/physiology
- Tyrosine/genetics
- Tyrosine/metabolism
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Affiliation(s)
- Kelly A Pike
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
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47
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Trescol-Biémont MC, Verschelde C, Cottalorda A, Bonnefoy-Bérard N. Regulation of A1/Bfl-1 expression in peripheral splenic B cells. Biochimie 2005; 86:287-94. [PMID: 15194232 DOI: 10.1016/j.biochi.2004.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Accepted: 04/05/2004] [Indexed: 01/25/2023]
Abstract
We analyzed here the expression of the prosurvival Bcl-2 homologue A1 in peripheral B cell compartment. We observed that A1 mRNA are highly expressed in peripheral B cells as compared with other anti-apoptotic genes of the Bcl-2 family such as bcl-xl and bcl-2 itself. The expression of A1 is up-regulated in immature B cells at the transition between transitional type 1 (T1) and type 2 (T2) cells, and remained highly expressed in mature (M) B cells. We, therefore, analyzed the effect of B cell antigen receptor (BCR) and BAFF receptor (BAFF-R) engagement on the regulation of A1 in total B220(+) cells but also FACS-sorted immature T1, T2 and M B cells. We demonstrated that only BCR engagement up-regulated the expression of A1 mRNA and protein. These results suggest that A1 may play a key role in antigen-dependent signals that are required for survival and/or proliferation of peripheral B cells.
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Affiliation(s)
- Marie-Claude Trescol-Biémont
- Inserm U503, IFR128 Bioscience Lyon-Gerland, Centre d'Etude et de Recherche en Virologie et Immunologie, 21, avenue Tony Garnier, 69365 Lyon cedex 7, France
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Diamant E, Keren Z, Melamed D. CD19 regulates positive selection and maturation in B lymphopoiesis: lack of CD19 imposes developmental arrest of immature B cells and consequential stimulation of receptor editing. Blood 2005; 105:3247-54. [PMID: 15644414 DOI: 10.1182/blood-2004-08-3165] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ligand-independent signals that are produced by the B-cell antigen receptor (BCR) confer an important positive selection checkpoint for immature B cells. Generation of inappropriate signals imposes developmental arrest of immature B cells, though the fate of these cells has not been investigated. Studies have shown that the lack of CD19 results in inappropriate signaling. In immunoglobulin transgenic mice, this inappropriate signaling impairs positive selection and stimulates receptor editing. Here, we studied the extent and significance of receptor editing in CD19-regulated positive selection of normal, nontransgenic B lymphopoiesis, using our bone marrow culture system. We found that the lack of CD19 resulted in elevated tonic signaling and impaired maturation, as revealed by surface marker expression and by functional assays. Immature CD19-/- B cells did not suppress RAG and underwent intensive receptor editing attempts in culture. Finally, in vivo analysis of light-chain isotype expression and Jkappa use in CD19-/- mice validated our in vitro observations. Our results suggest that CD19 has an important function in regulating positive selection and maturation of nontransgenic B-cell precursors and that receptor editing is an important salvage mechanism for immature B cells that fail positive selection.
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Affiliation(s)
- Eran Diamant
- Department of Immunology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
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49
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Kraus M, Alimzhanov MB, Rajewsky N, Rajewsky K. Survival of resting mature B lymphocytes depends on BCR signaling via the Igalpha/beta heterodimer. Cell 2004; 117:787-800. [PMID: 15186779 DOI: 10.1016/j.cell.2004.05.014] [Citation(s) in RCA: 444] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 04/08/2004] [Accepted: 04/12/2004] [Indexed: 12/19/2022]
Abstract
We previously showed that type I interferon-induced, Cre-mediated ablation of surface BCR expression in mature B cells through Ig-heavy chain deletion results in apoptosis of these cells. This led to the hypothesis that survival signals from the BCR are vital for mature B cells. Here, we test two critical assumptions of this model. First, we demonstrate loss of mature B cells upon induced mutation of a signaling module of the BCR, not precluding BCR surface expression. Second, we show that the cells are also lost upon BCR inactivation in the absence of an exogenous inducer like interferon, excluding that cell death depends on previous cellular activation by the latter. Kinetic data demonstrate that BCR-less mature B cells have a severely reduced lifespan, with a half-life of 3-6 days. Together these results establish that BCR signaling is required to keep resting mature B cells alive in vivo.
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Affiliation(s)
- Manfred Kraus
- New York University, Department of Biology, 1009 Main Building, 100 Washington Square East, New York, NY 10003, USA
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