1
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He J, Zeng X, Wang C, Wang E, Li Y. Antibody-drug conjugates in cancer therapy: mechanisms and clinical studies. MedComm (Beijing) 2024; 5:e671. [PMID: 39070179 PMCID: PMC11283588 DOI: 10.1002/mco2.671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 07/03/2024] [Accepted: 07/08/2024] [Indexed: 07/30/2024] Open
Abstract
Antibody-drug conjugates (ADCs) consist of monoclonal antibodies that target tumor cells and cytotoxic drugs linked through linkers. By leveraging antibodies' targeting properties, ADCs deliver cytotoxic drugs into tumor cells via endocytosis after identifying the tumor antigen. This precise method aims to kill tumor cells selectively while minimizing harm to normal cells, offering safe and effective therapeutic benefits. Recent years have seen significant progress in antitumor treatment with ADC development, providing patients with new and potent treatment options. With over 300 ADCs explored for various tumor indications and some already approved for clinical use, challenges such as resistance due to factors like antigen expression, ADC processing, and payload have emerged. This review aims to outline the history of ADC development, their structure, mechanism of action, recent composition advancements, target selection, completed and ongoing clinical trials, resistance mechanisms, and intervention strategies. Additionally, it will delve into the potential of ADCs with novel markers, linkers, payloads, and innovative action mechanisms to enhance cancer treatment options. The evolution of ADCs has also led to the emergence of combination therapy as a new therapeutic approach to improve drug efficacy.
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Affiliation(s)
- Jun He
- Department of General Surgery Jiande Branch of the Second Affiliated Hospital, School of Medicine, Zhejiang University Jiande Zhejiang China
| | - Xianghua Zeng
- Department of Medical Oncology Chongqing University Cancer Hospital Chongqing China
| | - Chunmei Wang
- Department of Medical Oncology Chongqing University Cancer Hospital Chongqing China
| | - Enwen Wang
- Department of Medical Oncology Chongqing University Cancer Hospital Chongqing China
| | - Yongsheng Li
- Department of Medical Oncology Chongqing University Cancer Hospital Chongqing China
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2
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Tkachenko A, Kupcova K, Havranek O. B-Cell Receptor Signaling and Beyond: The Role of Igα (CD79a)/Igβ (CD79b) in Normal and Malignant B Cells. Int J Mol Sci 2023; 25:10. [PMID: 38203179 PMCID: PMC10779339 DOI: 10.3390/ijms25010010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 01/12/2024] Open
Abstract
B-cell receptor (BCR) is a B cell hallmark surface complex regulating multiple cellular processes in normal as well as malignant B cells. Igα (CD79a)/Igβ (CD79b) are essential components of BCR that are indispensable for its functionality, signal initiation, and signal transduction. CD79a/CD79b-mediated BCR signaling is required for the survival of normal as well as malignant B cells via a wide signaling network. Recent studies identified the great complexity of this signaling network and revealed the emerging role of CD79a/CD79b in signal integration. In this review, we have focused on functional features of CD79a/CD79b, summarized signaling consequences of CD79a/CD79b post-translational modifications, and highlighted specifics of CD79a/CD79b interactions within BCR and related signaling cascades. We have reviewed the complex role of CD79a/CD79b in multiple aspects of normal B cell biology and how is the normal BCR signaling affected by lymphoid neoplasms associated CD79A/CD79B mutations. We have also summarized important unresolved questions and highlighted issues that remain to be explored for better understanding of CD79a/CD79b-mediated signal transduction and the eventual identification of additional therapeutically targetable BCR signaling vulnerabilities.
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Affiliation(s)
- Anton Tkachenko
- BIOCEV, First Faculty of Medicine, Charles University, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Kristyna Kupcova
- BIOCEV, First Faculty of Medicine, Charles University, Prumyslova 595, 252 50 Vestec, Czech Republic
- First Department of Internal Medicine–Hematology, General University Hospital and First Faculty of Medicine, Charles University, 128 08 Prague, Czech Republic
| | - Ondrej Havranek
- BIOCEV, First Faculty of Medicine, Charles University, Prumyslova 595, 252 50 Vestec, Czech Republic
- First Department of Internal Medicine–Hematology, General University Hospital and First Faculty of Medicine, Charles University, 128 08 Prague, Czech Republic
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3
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Bhanja A, Seeley-Fallen MK, Lazzaro M, Upadhyaya A, Song W. N-WASP-dependent branched actin polymerization attenuates B-cell receptor signaling by increasing the molecular density of receptor clusters. eLife 2023; 12:RP87833. [PMID: 38085658 PMCID: PMC10715734 DOI: 10.7554/elife.87833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023] Open
Abstract
Antigen-induced B-cell receptor (BCR) signaling is critical for initiating and regulating B-cell activation. The actin cytoskeleton plays essential roles in BCR signaling. Upon encountering cell-surface antigens, actin-driven B-cell spreading amplifies signaling, while B-cell contraction following spreading leads to signal attenuation. However, the mechanism by which actin dynamics switch BCR signaling from amplification to attenuation is unknown. Here, we show that Arp2/3-mediated branched actin polymerization is required for mouse splenic B-cell contraction. Contracting B-cells generate centripetally moving actin foci from lamellipodial F-actin networks in the plasma membrane region contacting antigen-presenting surfaces. Actin polymerization driven by N-WASP, but not WASP, initiates these actin foci and facilitates non-muscle myosin II recruitment to the contact zone, creating actomyosin ring-like structures. B-cell contraction increases BCR molecular density in individual clusters, leading to decreased BCR phosphorylation. Increased BCR molecular density reduced levels of the stimulatory kinase Syk, the inhibitory phosphatase SHIP-1, and their phosphorylated forms in individual BCR clusters. These results suggest that N-WASP-activated Arp2/3, coordinating with myosin, generates centripetally moving foci and contractile actomyosin ring-like structures from lamellipodial networks, enabling contraction. B-cell contraction attenuates BCR signaling by pushing out both stimulatory kinases and inhibitory phosphatases from BCR clusters, providing novel insights into actin-facilitated signal attenuation.
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Affiliation(s)
- Anshuman Bhanja
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Margaret K Seeley-Fallen
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Michelle Lazzaro
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Arpita Upadhyaya
- Biophysics Program, University of MarylandCollege ParkUnited States
- Department of Physics, University of MarylandCollege ParkUnited States
- Institute for Physical Science and Technology, University of MarylandCollege ParkUnited States
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
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4
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Bhanja A, Seeley-Fallen MK, Lazzaro M, Upadhyaya A, Song W. N-WASP-dependent branched actin polymerization attenuates B-cell receptor signaling by increasing the molecular density of receptor clusters. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532631. [PMID: 36993351 PMCID: PMC10055065 DOI: 10.1101/2023.03.14.532631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Antigen-induced B-cell receptor (BCR) signaling is critical for initiating and regulating B-cell activation. The actin cytoskeleton plays essential roles in BCR signaling. Upon encountering cell-surface antigens, actin-driven B-cell spreading amplifies signaling, while B-cell contraction following spreading leads to signal attenuation. However, the mechanism by which actin dynamics switch BCR signaling from amplification to attenuation is unknown. Here, we show that Arp2/3-mediated branched actin polymerization is required for B-cell contraction. Contracting B-cells generate centripetally moving actin foci from lamellipodial F-actin networks in the B-cell plasma membrane region contacting antigen-presenting surfaces. Actin polymerization driven by N-WASP, but not WASP, initiates these actin foci and facilitates non-muscle myosin II recruitment to the contact zone, creating actomyosin ring-like structures. Furthermore, B-cell contraction increases BCR molecular density in individual clusters, leading to decreased BCR phosphorylation. Increased BCR molecular density reduced levels of the stimulatory kinase Syk, the inhibitory phosphatase SHIP-1, and their phosphorylated forms in individual BCR clusters. These results suggest that N-WASP-activated Arp2/3, coordinating with myosin, generates centripetally moving foci and contractile actomyosin ring-like structures from lamellipodial networks, enabling contraction. B-cell contraction attenuates BCR signaling by pushing out both stimulatory kinases and inhibitory phosphatases from BCR clusters, providing novel insights into actin-facilitated signal attenuation.
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Affiliation(s)
- Anshuman Bhanja
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Margaret K. Seeley-Fallen
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Michelle Lazzaro
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Arpita Upadhyaya
- Biophysics Program, University of Maryland, College Park, MD, 20742, USA
- Department of Physics, University of Maryland, College Park, MD, 20742, USA
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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5
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Shorer Arbel Y, Bronstein Y, Dadosh T, Kamdjou T, Tsuriel S, Shapiro M, Katz BZ, Herishanu Y. Spatial organization and early signaling of the B-cell receptor in CLL. Front Immunol 2022; 13:953660. [PMID: 36016925 PMCID: PMC9398492 DOI: 10.3389/fimmu.2022.953660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/08/2022] [Indexed: 11/28/2022] Open
Abstract
Most chronic lymphocytic leukemia (CLL) clones express B-cell receptors (BcR) of both IgM/IgD isotypes; however, 5%–10% of CLL cases express isotype-switched immunoglobulin G (IgG). The early signaling and spatial patterning of the various BcRs at steady state and after activation are still fully unresolved. Herein, we show higher expression of the BcR signalosome elements and a more robust constitutive cell-intrinsic proximal BcR signaling in CLL with unmutated IGHV expressing IgM isotype (IgM U-CLL), compared with IGHV-mutated CLL (M-CLL) expressing either IgM or IgG isotypes. IgM in U-CLL is frequently located in the membrane plane in polarized patches, occasionally in caps, and sometimes inside the cells. Among M-CLL, IgM is scattered laterally in the membrane plane in a similar pattern as seen in normal B cells, whereas IgG is dispersed around the cell membrane in smaller clusters than in IgM U-CLL. Upon BcR engagement, both IgG and IgM expressing M-CLL showed attenuated signaling and only slight spatial reorganization dynamics of BcR microclusters and internalization, compared with the extensive reorganization and internalization of the BcR in IgM expressing U-CLL. The global gene signature of IgG M-CLL was closely related to that of IgM M-CLL rather than IgM U-CLL. Overall, we report fundamental differences in the basal composition, biochemical status, and spatial organization of the BcR in the three examined immunogenetic CLL subtypes that correlate with their clinical behavior. On the basis of our findings, IgG class-switched M-CLL likely represents the same disease as IgM M-CLL rather than a different biological and/or clinical entity.
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MESH Headings
- Humans
- Immunoglobulin G
- Immunoglobulin M
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Signal Transduction
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Affiliation(s)
| | - Yotam Bronstein
- Department of Hematology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Tali Dadosh
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Talia Kamdjou
- Department of Hematology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Shlomo Tsuriel
- Department of Pathology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Mika Shapiro
- Department of Hematology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Ben-Zion Katz
- Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel
- Department of Hematology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Yair Herishanu
- Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel
- Department of Hematology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- *Correspondence: Yair Herishanu,
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6
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Enterina JR, Sarkar S, Streith L, Jung J, Arlian BM, Meyer SJ, Takematsu H, Xiao C, Baldwin TA, Nitschke L, Shlomchick MJ, Paulson JC, Macauley MS. Coordinated changes in glycosylation regulate the germinal center through CD22. Cell Rep 2022; 38:110512. [PMID: 35294874 PMCID: PMC9018098 DOI: 10.1016/j.celrep.2022.110512] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 01/19/2022] [Accepted: 02/16/2022] [Indexed: 12/18/2022] Open
Abstract
Germinal centers (GCs) are essential for antibody affinity maturation. GC B cells have a unique repertoire of cell surface glycans compared with naive B cells, yet functional roles for changes in glycosylation in the GC have yet to be ascribed. Detection of GCs by the antibody GL7 reflects a downregulation in ligands for CD22, an inhibitory co-receptor of the B cell receptor. To test a functional role for downregulation of CD22 ligands in the GC, we generate a mouse model that maintains CD22 ligands on GC B cells. With this model, we demonstrate that glycan remodeling plays a critical role in the maintenance of B cells in the GC. Sustained expression of CD22 ligands induces higher levels of apoptosis in GC B cells, reduces memory B cell and plasma cell output, and delays affinity maturation of antibodies. These defects are CD22 dependent, demonstrating that downregulation of CD22 ligands on B cells plays a critical function in the GC.
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Affiliation(s)
- Jhon R Enterina
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Susmita Sarkar
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada
| | - Laura Streith
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Jaesoo Jung
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada
| | - Britni M Arlian
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sarah J Meyer
- Division of Genetics, Department of Biology, University of Erlangen, 91058 Erlangen, Germany
| | - Hiromu Takematsu
- Faculty of Medical Technology, Fujita Health University, Aichi 470-1192, Japan
| | - Changchun Xiao
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Troy A Baldwin
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Lars Nitschke
- Division of Genetics, Department of Biology, University of Erlangen, 91058 Erlangen, Germany
| | - Mark J Shlomchick
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - James C Paulson
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Matthew S Macauley
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada; Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada.
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7
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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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8
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The emerging roles of semaphorin4D/CD100 in immunological diseases. Biochem Soc Trans 2021; 48:2875-2890. [PMID: 33258873 DOI: 10.1042/bst20200821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 02/05/2023]
Abstract
In vertebrates, the semaphorin family of proteins is composed of 21 members that are divided into five subfamilies, i.e. classes 3 to 7. Semaphorins play crucial roles in regulating multiple biological processes, such as neural remodeling, tissue regeneration, cancer progression, and, especially, in immunological regulation. Semaphorin 4D (SEMA4D), also known as CD100, is an important member of the semaphorin family and was first characterized as a lymphocyte-specific marker. SEMA4D has diverse effects on immunologic processes, including immune cell proliferation, differentiation, activation, and migration, through binding to its specific membrane receptors CD72, PLXNB1, and PLXNB2. Furthermore, SEMA4D and its underlying signaling have been increasingly linked with several immunological diseases. This review focuses on the significant immunoregulatory role of SEMA4D and the associated underlying mechanisms, as well as the potential application of SEMA4D as a diagnostic marker and therapeutic target for the treatment of immunological diseases.
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9
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Alborzian Deh Sheikh A, Akatsu C, Abdu-Allah HHM, Suganuma Y, Imamura A, Ando H, Takematsu H, Ishida H, Tsubata T. The Protein Tyrosine Phosphatase SHP-1 (PTPN6) but Not CD45 (PTPRC) Is Essential for the Ligand-Mediated Regulation of CD22 in BCR-Ligated B Cells. THE JOURNAL OF IMMUNOLOGY 2021; 206:2544-2551. [PMID: 33990399 DOI: 10.4049/jimmunol.2100109] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/01/2021] [Indexed: 11/19/2022]
Abstract
CD22 is an inhibitory B cell coreceptor that regulates B cell development and activation by downregulating BCR signaling through activation of SH2-containing protein tyrosine phosphatase-1 (SHP-1). CD22 recognizes α2,6 sialic acid as a specific ligand and interacts with α2,6 sialic acid-containing membrane molecules, such as CD45, IgM, and CD22, expressed on the same cell. Functional regulation of CD22 by these endogenous ligands enhances BCR ligation-induced signaling and is essential for normal B cell responses to Ags. In this study, we demonstrate that CD45 plays a crucial role in CD22-mediated inhibition of BCR ligation-induced signaling. However, disruption of ligand binding of CD22 enhances CD22 phosphorylation, a process required for CD22-mediated signal inhibition, upon BCR ligation in CD45-/- as well as wild-type mouse B cells but not in mouse B cells expressing a loss-of-function mutant of SHP-1. This result indicates that SHP-1 but not CD45 is required for ligand-mediated regulation of CD22. We further demonstrate that CD22 is a substrate of SHP-1, suggesting that SHP-1 recruited to CD22 dephosphorylates nearby CD22 as well as other substrates. CD22 dephosphorylation by SHP-1 appears to be augmented by homotypic CD22 clustering mediated by recognition of CD22 as a ligand of CD22 because CD22 clustering increases the number of nearby CD22. Our results suggest that CD22 but not CD45 is an endogenous ligand of CD22 that enhances BCR ligation-induced signaling through SHP-1-mediated dephosphorylation of CD22 in CD22 clusters.
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Affiliation(s)
- Amin Alborzian Deh Sheikh
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Chizuru Akatsu
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | | | - Yuki Suganuma
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Akihiro Imamura
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Hiromune Ando
- Center for Highly Advanced Integration of Nano and Life Sciences, Gifu University, Gifu, Japan.,Institute for Glyco-core Research, Gifu University, Gifu, Japan; and
| | - Hiromu Takematsu
- Faculty of Medical Technology, Fujita Health University, Toyoake, Aichi, Japan
| | - Hideharu Ishida
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan.,Center for Highly Advanced Integration of Nano and Life Sciences, Gifu University, Gifu, Japan
| | - Takeshi Tsubata
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan;
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10
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Tsugawa N, Yamada D, Watabe T, Onizawa M, Wang S, Nemoto Y, Oshima S, Tsubata T, Adachi T, Kawano Y, Watanabe M, Blumberg RS, Okamoto R, Nagaishi T. CEACAM1 specifically suppresses B cell receptor signaling-mediated activation. Biochem Biophys Res Commun 2021; 535:99-105. [PMID: 33352461 PMCID: PMC9635307 DOI: 10.1016/j.bbrc.2020.11.126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 11/30/2020] [Indexed: 01/28/2023]
Abstract
Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) expressed in T cells may regulate immune responses in the gut. In addition to T cells, B cells are also an important population in the gut-associated lymphoid tissues that orchestrate mucosal homeostasis. However, the role of CEACAM1 in B cells has not been elucidated. We herein analyzed mature B cells to determine the functions of CEACAM1. Flow cytometry revealed high expression of CEACAM1 on B cells in secondary lymphoid tissues. Cytokine production induced by activation of B cell receptor (BCR) signaling was suppressed by CEACAM1 signaling in contrast to that associated with either Toll-like receptor 4 or CD40 signaling. Confocal microscopy revealed co-localization of CEACAM1 and BCR when activated with anti-Igμ F(ab')2 fragment. Overexpression of CEACAM1 in a murine B cell line, A20, resulted in reduced expressions of activation surface markers with decreased Ca2+ influx after BCR signal activation. Overexpression of CEACAM1 suppressed BCR signal cascade in A20 cells in association with decreased spontaneous proliferation. Our results suggest that CEACAM1 can regulate BCR-mediated mature B cell activation in lymphoid tissues. Therefore, further studies of this molecule may lead to greater insights into the mechanisms of immune responses within peripheral tissues and the potential treatment of inflammatory diseases.
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Affiliation(s)
- Naoya Tsugawa
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Daiki Yamada
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Taro Watabe
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Michio Onizawa
- Department of Advanced Therapeutics for GI Diseases, Graduate School of Medical Science, TMDU, Tokyo, Japan
| | - Shuang Wang
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Faculty of Medicine, Imperial College London, London, UK
| | - Yasuhiro Nemoto
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Department of Advanced Therapeutics for GI Diseases, Graduate School of Medical Science, TMDU, Tokyo, Japan
| | - Shigeru Oshima
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Takeshi Tsubata
- Department of Immunology, Medical Research Institute (MRI), TMDU, Tokyo, Japan
| | - Takahiro Adachi
- Department of Immunology, Medical Research Institute (MRI), TMDU, Tokyo, Japan
| | - Yohei Kawano
- Department of Immune Regulation, Graduate School of Medical Science, TMDU, Tokyo, Japan
| | - Mamoru Watanabe
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Advanced Research Institute, TMDU, Tokyo, Japan
| | - Richard S Blumberg
- Gastroenterology Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ryuichi Okamoto
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Takashi Nagaishi
- Department of Advanced Therapeutics for GI Diseases, Graduate School of Medical Science, TMDU, Tokyo, Japan.
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11
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Enhanced BCR signaling inflicts early plasmablast and germinal center B cell death. iScience 2021; 24:102038. [PMID: 33532715 PMCID: PMC7822941 DOI: 10.1016/j.isci.2021.102038] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 11/20/2020] [Accepted: 01/04/2021] [Indexed: 01/01/2023] Open
Abstract
It is still not clear how B cell receptor (BCR) signaling intensity affects plasma cell (PC) and germinal center (GC) B cell differentiation. We generated Cγ1 Cre/wt Ptpn6 fl/fl mice where SHP-1, a negative regulator of BCR signaling, is deleted rapidly after B cell activation. Although immunization with T-dependent antigens increased BCR signaling, it led to PC reduction and increased apoptosis. Dependent on the antigen, the early GC B cell response was equally reduced and apoptosis increased. At the same time, a higher proportion of GC B cells expressed cMYC, suggesting GC B cell-Tfh cell interactions may be increased. GC B cell numbers returned to normal at later stages, whereas affinity maturation was suppressed in the long term. This confirms that BCR signaling not only directs affinity-dependent B cell selection but also, without adequate further stimulation, can inflict cell death, which may be important for the maintenance of B cell tolerance.
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12
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Davidzohn N, Biram A, Stoler-Barak L, Grenov A, Dassa B, Shulman Z. Syk degradation restrains plasma cell formation and promotes zonal transitions in germinal centers. J Exp Med 2020; 217:133542. [PMID: 31873727 PMCID: PMC7062533 DOI: 10.1084/jem.20191043] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 10/08/2019] [Accepted: 11/18/2019] [Indexed: 12/14/2022] Open
Abstract
In germinal centers, B cells interact with antigen in the light zone and clonally expand in the dark zone. Davidzohn et al. show that BCR-induced Syk degradation in the light zone attenuates signal transduction, impedes plasma cell formation, and promotes B cell transition to the dark zone. Germinal centers (GCs) are sites at which B cells proliferate and mutate their antibody-encoding genes in the dark zone (DZ), followed by affinity-based selection in the light zone (LZ). B cell antigen receptor (BCR) signals induce Syk activation followed by rapid phosphatase-mediated desensitization; however, how degradation events regulate BCR functions in GCs is unclear. Here, we found that Syk degradation restrains plasma cell (PC) formation in GCs and promotes B cell LZ to DZ transition. Using a mouse model defective in Cbl-mediated Syk degradation, we demonstrate that this machinery attenuates BCR signaling intensity by mitigating the Kras/Erk and PI3K/Foxo1 pathways, and restricting the expression of PC transcription factors in GC B cells. Inhibition of Syk degradation perturbed gene expression, specifically in the LZ, and enhanced the generation of PCs without affecting B cell proliferation. These findings reveal how long-lasting attenuation of signal transduction by degradation events regulates cell fate within specialized microanatomical sites.
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Affiliation(s)
- Natalia Davidzohn
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Adi Biram
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Liat Stoler-Barak
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Amalie Grenov
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Bareket Dassa
- Department of Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Ziv Shulman
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
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13
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Signalling circuits that direct early B-cell development. Biochem J 2019; 476:769-778. [PMID: 30842310 DOI: 10.1042/bcj20180565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/11/2019] [Accepted: 02/15/2019] [Indexed: 12/23/2022]
Abstract
In mammals, the B-cell lineage arises from pluripotent progenitors in the bone marrow. During their development, B-cells undergo lineage specification and commitment, followed by expansion and selection. These processes are mediated by regulated changes in gene expression programmes, rearrangements of immunoglobulin (Ig) genes, and well-timed rounds of proliferation and apoptosis. Many of these processes are initiated by environmental factors including cytokines, chemokines, and cell-cell contacts. Developing B-cells process these environmental cues into stage-specific functions via signalling pathways including the PI3K, MAPK, or JAK-STAT pathway. The cytokines FLT3-Ligand and c-Kit-Ligand are important for the early expansion of the B-cell precursors at different developmental stages and conditions. Interleukin 7 is essential for commitment to the B-cell lineage and for orchestrating the Ig recombination machinery. After rearrangement of the immunoglobulin heavy chain, proliferation and apoptosis, and thus selection, are mediated by the clonal pre-B-cell receptor, and, following light chain rearrangement, by the B-cell receptor.
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Tsubata T. Ligand Recognition Determines the Role of Inhibitory B Cell Co-receptors in the Regulation of B Cell Homeostasis and Autoimmunity. Front Immunol 2018; 9:2276. [PMID: 30333834 PMCID: PMC6175988 DOI: 10.3389/fimmu.2018.02276] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/13/2018] [Indexed: 01/13/2023] Open
Abstract
B cells express various inhibitory co-receptors including CD22, CD72, and Siglec-G. These receptors contain immunoreceptor tyrosine-based inhibition motifs (ITIMs) in the cytoplasmic region. Although many of the inhibitory co-receptors negatively regulate BCR signaling by activating SH2-containing protein tyrosine phosphatase 1 (SHP-1), different inhibitory co-receptors have distinct functional properties. CD22, Siglec-G, and CD72 preferentially regulate tonic signaling in conventional B cells, B-1 cell homeostasis, and development of lupus-like disease, respectively. CD72 recognizes RNA-related lupus self-antigen Sm/RNP as a ligand. This ligand recognition recruits CD72 to BCR in Sm/RNP-reactive B cells thereby suppressing production of anti-Sm/RNP autoantibody involved in the pathogenesis of lupus. In contrast, Siglec-G recognizes α2,3 as well as α2,6 sialic acids whereas CD22 recognizes α2,6 sialic acid alone. Because glycoproteins including BCR are dominantly glycosylated with α2,3 sialic acids in B-1 cells, Siglec-G but not CD22 recruits BCR as a ligand specifically in B-1 cells, and regulates B-1 cell homeostasis by suppressing BCR signaling in B-1 cells. Thus, recognition of distinct ligands determines functional properties of different inhibitory B cell co-receptors.
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Affiliation(s)
- Takeshi Tsubata
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
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15
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Lotfi R, Yari K. The Role of Semaphorins and their Receptors in the Immune System and their Relation to Multiple Sclerosis. ACTA ACUST UNITED AC 2018. [DOI: 10.29252/shefa.6.4.75] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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16
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Franks SE, Cambier JC. Putting on the Brakes: Regulatory Kinases and Phosphatases Maintaining B Cell Anergy. Front Immunol 2018; 9:665. [PMID: 29681901 PMCID: PMC5897502 DOI: 10.3389/fimmu.2018.00665] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/19/2018] [Indexed: 12/21/2022] Open
Abstract
B cell antigen receptor (BCR) signaling is a tightly regulated process governed by both positive and negative mediators/regulators to ensure appropriate responses to exogenous and autologous antigens. Upon naïve B cell recognition of antigen CD79 [the immunoreceptor tyrosine-based activation motif (ITAM)-containing signaling subunit of the BCR] is phosphorylated and recruits Src and Syk family kinases that then phosphorylate proximal intermediaries linked to downstream activating signaling circuitry. This plasma membrane localized signalosome activates PI3K leading to generation of PIP3 critical for membrane localization and activation of plecktrin homology domain-containing effectors. Conversely, in anergic B cells, chronic antigen stimulation drives biased monophosphorylation of CD79 ITAMs leading to recruitment of Lyn, but not Syk, which docks only to bi-phosphorylated ITAMS. In this context, Lyn appears to function primarily as a driver of inhibitory signaling pathways promoting the inhibition of the PI3K pathway by inositol phosphatases, SHIP-1 and PTEN, which hydrolyze PIP3 to PIP2. Lyn may also exert negative regulation of signaling through recruitment of SHP-1, a tyrosine phosphatase that dephosphorylates activating signaling molecules. Alleles of genes that encode or regulate expression of components of this axis, including SHIP-1, SHP-1, Csk/PTPn22, and Lyn, have been shown to confer risk of autoimmunity. This review will discuss functional interplay of components of this pathway and the impact of risk alleles on its function.
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Affiliation(s)
- S Elizabeth Franks
- Department of Immunology and Microbiology, University of Colorado Denver School of Medicine, Aurora, CO, United States
| | - John C Cambier
- Department of Immunology and Microbiology, University of Colorado Denver School of Medicine, Aurora, CO, United States
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Getahun A, Beavers NA, Larson SR, Shlomchik MJ, Cambier JC. Continuous inhibitory signaling by both SHP-1 and SHIP-1 pathways is required to maintain unresponsiveness of anergic B cells. J Exp Med 2016; 213:751-69. [PMID: 27114609 PMCID: PMC4854724 DOI: 10.1084/jem.20150537] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 03/10/2016] [Indexed: 01/19/2023] Open
Abstract
Cambier et al. show that the tyrosine phosphatase SHP-1 and the inositol phosphatase SHIP-1 are required to maintain B cell anergy. Many autoreactive B cells persist in the periphery in a state of unresponsiveness called anergy. This unresponsiveness is rapidly reversible, requiring continuous BCR interaction with self-antigen and resultant regulatory signaling for its maintenance. Using adoptive transfer of anergic B cells with subsequent acute induction of gene deletion or expression, we demonstrate that the continuous activities of independent inhibitory signaling pathways involving the tyrosine phosphatase SHP-1 and the inositol phosphatase SHIP-1 are required to maintain anergy. Acute breach of anergy by compromise of either of these pathways leads to rapid cell activation, proliferation, and generation of short-lived plasma cells that reside in extrafollicular foci. Results are consistent with predicted/observed reduction in the Lyn–SHIP-1–PTEN–SHP-1 axis function in B cells from systemic lupus erythematosus patients.
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Affiliation(s)
- Andrew Getahun
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045 Department of Biomedical Research, National Jewish Health, Denver, CO 80206
| | - Nicole A Beavers
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045 Department of Biomedical Research, National Jewish Health, Denver, CO 80206
| | - Sandy R Larson
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045 Department of Biomedical Research, National Jewish Health, Denver, CO 80206
| | - Mark J Shlomchik
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - John C Cambier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045 Department of Biomedical Research, National Jewish Health, Denver, CO 80206
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Alsadeq A, Hobeika E, Medgyesi D, Kläsener K, Reth M. The role of the Syk/Shp-1 kinase-phosphatase equilibrium in B cell development and signaling. THE JOURNAL OF IMMUNOLOGY 2014; 193:268-76. [PMID: 24899508 DOI: 10.4049/jimmunol.1203040] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Signal transduction from the BCR is regulated by the equilibrium between kinases (e.g., spleen tyrosine kinase [Syk]) and phosphatases (e.g., Shp-1). Previous studies showed that Syk-deficient B cells have a developmental block at the pro/pre-B cell stage, whereas a B cell-specific Shp-1 deficiency promoted B-1a cell development and led to autoimmunity. We generated B cell-specific Shp-1 and Syk double-knockout (DKO) mice and compared them to the single-knockout mice deficient for either Syk or Shp-1. Unlike Syk-deficient mice, the DKO mice can generate mature B cells, albeit at >20-fold reduced B cell numbers. The DKO B-2 cells are all Syk-negative, whereas the peritoneal B1 cells of the DKO mice still express Syk, indicating that they require this kinase for their proper development. The DKO B-2 cells cannot be stimulated via the BCR, whereas they are efficiently activated via TLR or CD40. We also found that in DKO pre-B cells, the kinase Zap70 is associated with the pre-BCR, suggesting that Zap70 is important to promote B cell maturation in the absence of Syk and SHP-1. Together, our data show that a properly balanced kinase/phosphatase equilibrium is crucial for normal B cell development and function.
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Affiliation(s)
- Ameera Alsadeq
- Department of Molecular Immunology, Max-Planck-Institut of Immunobiology and Epigenetics, Freiburg 79108, Germany; Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany; and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany
| | - Elias Hobeika
- Department of Molecular Immunology, Max-Planck-Institut of Immunobiology and Epigenetics, Freiburg 79108, Germany; Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany
| | - David Medgyesi
- Department of Molecular Immunology, Max-Planck-Institut of Immunobiology and Epigenetics, Freiburg 79108, Germany; Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany
| | - Kathrin Kläsener
- Department of Molecular Immunology, Max-Planck-Institut of Immunobiology and Epigenetics, Freiburg 79108, Germany; Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany
| | - Michael Reth
- Department of Molecular Immunology, Max-Planck-Institut of Immunobiology and Epigenetics, Freiburg 79108, Germany; Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany; and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg 79108, Germany
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Harumiya S, Yoshino A, Hayashizaki K, Mizuno K, Yakura H, Adachi T. A system for reconstructing B cell antigen receptor signaling in the mouse myeloma J558L cell line. Arch Biochem Biophys 2013; 533:18-24. [PMID: 23454348 DOI: 10.1016/j.abb.2013.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 02/06/2013] [Accepted: 02/15/2013] [Indexed: 11/28/2022]
Abstract
B cell antigen receptor (BCR) signaling is positively and negatively regulated by various cell surface receptors such as CD19 and CD45. Functional analysis of these receptors has been performed using gene targeting technology, which is a valid approach to elucidate their functions. However, this type of analysis is restricted when multiple molecules are evaluated simultaneously. From a different perspective, synthetic biology provides a high degree of freedom for analyzing various molecules. Here we developed a system to reconstruct BCR signaling using the J558L myeloma cell line in combination with the protein-based Ca(2+) indicator YC3.60. BCR-reconstituted J558L cells harboring YC3.60 (J558Lμv11 cells) permitted monitoring of Ca(2+) mobilization. Reconstituting CD19 in J558Lμv11 cells resulted in detectable BCR-induced Ca(2+) mobilization but with kinetics different from that of CD45-expressing cells. Furthermore, we evaluated the validity of the J558L system by proteomic analysis of tyrosine-phosphorylated proteins after antigen stimulation. Identification of more than 100 BCR-induced tyrosine-phosphorylated proteins in J558Lμv11 cells revealed a similarity to that observed in B cells, and a novel member, non-receptor protein tyrosine kinase Fer, was found. Thus, this reconstruction system using J558L cells appeared to be valid for comprehensively investigating BCR signaling.
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Affiliation(s)
- Satoru Harumiya
- Department of Cell signaling, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
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20
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Human CD72 splicing isoform responsible for resistance to systemic lupus erythematosus regulates serum immunoglobulin level and is localized in endoplasmic reticulum. BMC Immunol 2012; 13:72. [PMID: 23268649 PMCID: PMC3565990 DOI: 10.1186/1471-2172-13-72] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 12/21/2012] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND CD72 is an inhibitory co-receptor expressed on B cells. We previously demonstrated significant association of the polymorphism of the CD72 gene with susceptibility to human systemic lupus erythematosus (SLE) in individuals carrying a SLE-susceptible FCGR2B genotype (FCGR2B-232Thr/Thr). The human CD72 locus generates a splicing isoform that lacks exon 8 (CD72Δex8) as well as full-length CD72 (CD72fl), and the CD72 polymorphism regulates exon 8 skipping. RESULTS Here we demonstrated that individuals carrying the disease-protective CD72 genotype exhibit significantly lower serum immunoglobulin levels than do individuals carrying other CD72 genotypes (P < 0.05). Although expression level of CD72fl in the peripheral blood B cells was similar regardless of CD72 genotype, the protein level of CD72Δex8 was increased in individuals carrying the disease-protective CD72 genotype, suggesting a crucial role of CD72Δex8 in regulation of antibody production. By expressing these human CD72 isoforms in mouse cell lines, we further demonstrated that CD72Δex8 is accumulated in endoplasmic reticulum (ER) and fails to regulate BCR signaling whereas human CD72fl is efficiently transported to the cell surface and inhibits signaling through the B cell antigen receptor (BCR), as is the case for mouse CD72. CONCLUSION Human CD72 polymorphism appears to regulate antibody production as well as susceptibility to SLE by regulating expression of ER-localizing CD72Δex8.
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Adachi T, Harumiya S, Takematsu H, Kozutsumi Y, Wabl M, Fujimoto M, Tedder TF. CD22 serves as a receptor for soluble IgM. Eur J Immunol 2011; 42:241-7. [PMID: 21956693 DOI: 10.1002/eji.201141899] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 08/16/2011] [Accepted: 09/20/2011] [Indexed: 01/01/2023]
Abstract
CD22 (Siglec-2) is a B-cell membrane-bound lectin that recognizes glycan ligands containing α2,6-linked sialic acid (α2,6Sia) and negatively regulates signaling through the B-cell Ag receptor (BCR). Although CD22 has been investigated extensively, its precise function remains unclear due to acting multiple phases. Here, we demonstrate that CD22 is efficiently activated in trans by complexes of Ag and soluble IgM (sIgM) due to the presence of glycan ligands on sIgM. This result strongly suggests sIgM as a natural trans ligand for CD22. Also, CD22 appears to serve as a receptor for sIgM, which induces a negative feedback loop for B-cell activation similar to the Fc receptor for IgG (FcγRIIB).
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Affiliation(s)
- Takahiro Adachi
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
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22
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Vadasz Z, Attias D, Kessel A, Toubi E. Neuropilins and semaphorins - from angiogenesis to autoimmunity. Autoimmun Rev 2010; 9:825-9. [PMID: 20678594 DOI: 10.1016/j.autrev.2010.07.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 07/23/2010] [Indexed: 01/13/2023]
Abstract
Angiogenesis, the growth of new blood vessels from preexisting ones, is an important process in health and disease. The persistence of neovascularization in inflammatory diseases, such as rheumatoid arthritis (RA), might facilitate the entrance of inflammatory cells into the synovium and stimulate pannus formation. Several potent pro-angiogenic cytokines have been implicated in inflammatory angiogenesis. Of these, vascular endothelial growth factor (VEGF) and its receptors (VEGFRs) have been demonstrated to play a central role in RA, systemic lupus erythematosus (SLE) and multiple sclerosis (MS). Increased serum levels of VEGF were found to correlate with disease activity and severity of these diseases whereas, remission was associated with decreased levels. In the last few years, other molecules, initially found in neurodevelopment, were found to be involved in angiogenesis and recently also in the immune system and autoimmunity. Neuropilins (NPs) are VEGF receptors, while some of the semaphorins (SEMAs) are neuropilins' ligands. Their involvement in the development of autoimmune diseases and the various mechanisms by which they may induce autoimmunity will be discussed in this review.
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Affiliation(s)
- Z Vadasz
- Bnai-Zion Medical Center, Technion Institute, Haifa, Israel
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23
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Liu W, Meckel T, Tolar P, Sohn HW, Pierce SK. Antigen affinity discrimination is an intrinsic function of the B cell receptor. ACTA ACUST UNITED AC 2010; 207:1095-111. [PMID: 20404102 PMCID: PMC2867278 DOI: 10.1084/jem.20092123] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Antibody affinity maturation, a hallmark of adaptive immune responses, results from the selection of B cells expressing somatically hypermutated B cell receptors (BCRs) with increased affinity for antigens. Despite the central role of affinity maturation in antibody responses, the molecular mechanisms by which the increased affinity of a B cell for antigen is translated into a selective advantage for that B cell in immune responses is incompletely understood. We use high resolution live-cell imaging to provide evidence that the earliest BCR-intrinsic events that follow within seconds of BCR-antigen binding are highly sensitive to the affinity of the BCR for antigen. High affinity BCRs readily form oligomers and the resulting microclusters grow rapidly, resulting in enhanced recruitment of Syk kinase and calcium fluxes. Thus, B cells are able to read the affinity of antigen by BCR-intrinsic mechanisms during the earliest phases of BCR clustering, leading to the initiation of B cell responses.
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Affiliation(s)
- Wanli Liu
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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24
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Takegahara N, Kumanogoh A. Involvement of semaphorins and their receptors in neurological diseases. ACTA ACUST UNITED AC 2010. [DOI: 10.1111/j.1759-1961.2009.00004.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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25
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Abstract
Various abnormalities have been described in B cells from patients with systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and lupus-prone mice. Many of the abnormalities do not appear to be connected with the pathogenesis of the disease. However, various animal models developing lupus-like disease including both spontaneous mutans such as (NZB x NZW)F1 and MRL/lpr and mice generated by transgenic or knockout technology such as Bim-deficient and CD40L-transgenic mice show defect in apoptosis of mature B cells induced by ligation of the B cell antigen receptor (BCR). BCR-mediated apoptosis appears to be involved in deletion of self-reactive B cells. Thus, defect in BCR-mediated apoptosis is a widely observed B cell abnormality in lupus-prone mice and may play a role in the pathogenesis of systemic autoimmune diseases by abrogating deletion of self-reactive B cells.
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Affiliation(s)
- Takeshi Tsubata
- Laboratory of Immunology, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
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26
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Dasu T, Sindhava V, Clarke SH, Bondada S. CD19 signaling is impaired in murine peritoneal and splenic B-1 B lymphocytes. Mol Immunol 2009; 46:2655-65. [PMID: 19541367 DOI: 10.1016/j.molimm.2009.04.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Accepted: 04/16/2009] [Indexed: 01/02/2023]
Abstract
B-1 cells reside predominantly within the coelomic cavities, tonsils, Peyer's patches, spleen (a minor fraction - approximately 5%) and are absent in the lymph nodes. They are the primary sources of natural IgM in the body. B-1 cells express polyreactive B cell receptors (BCRs) that cross react with self-antigens and are thus implicated in auto-immune disorders. Previously, we reported that peritoneal B-1 cells are deficient in CD19-mediated intracellular signals leading to Ca(2+) mobilization. Here, we find that splenic B-1 cells, like peritoneal B-1 cells, are defective in Ca(2+) release upon B cell activation by co-cross-linking BCR and CD19. In the absence of extracellular sources of Ca(2+), intracellular Ca(2+) flux is similar between B-1 and B-2 cells. Moreover, the intracellular component of Ca(2+) release in both subsets of B cells is mostly PI3K dependent. BCR and CD19 co-cross-linking activates Akt, a key mediator of survival and proliferation signals downstream of PI3K in splenic B-2 cells. Splenic B-1 cells, on the other hand, do not phosphorylate Akt (S473) upon similar treatment. Furthermore, BCR+CD19 cross-linking induced phosphorylation of JNK is much reduced in splenic B-1 cells. In contrast, B-1 cells exhibited increased levels of constitutively active pLyn which appears to have an inhibitory role. The CD19 induced Ca(2+) response and BCR induced proliferation response were restored by a partial inhibition of pLyn with Src kinase specific inhibitors. These findings suggest a defect in CD19-mediated signals in both peritoneal and splenic B-1 B lymphocytes, which is in part, due to higher levels of constitutively active Lyn.
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Affiliation(s)
- Trivikram Dasu
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky, Lexington, 40536-0298, United States
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27
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Lobo EO, Zhang Z, Shively JE. Pivotal advance: CEACAM1 is a negative coreceptor for the B cell receptor and promotes CD19-mediated adhesion of B cells in a PI3K-dependent manner. J Leukoc Biol 2009; 86:205-18. [PMID: 19454653 DOI: 10.1189/jlb.0109037] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Upon antigen binding, the BCR transduces a signal culminating in proliferation or in AICD of the B cell. Coreceptor engagement and subsequent modification of the BCR signal pathway are mechanisms that guide the B cell to its appropriate fate. For example, in the absence of coreceptor engagement, anti-sIgM antibodies induce apoptosis in the human Daudi B cell lymphoma cell line. ITIM-bearing B cell coreceptors that potentially may act as negative coreceptors include FcRgammaIIb, CD22, CD72, and CEACAM1 (CD66a). Although the role of CEACAM1 as an inhibitory coreceptor in T cells has been established, its role in B cells is poorly defined. We show that anti-sIgM antibody and PI3K inhibitor LY294002-induced apoptosis are reduced significantly in CEACAM1 knock-down clones compared with WT Daudi cells and that anti-sIgM treatment induced CEACAM1 tyrosine phosphorylation and association with SHP-1 in WT cells. In contrast, treatment of WT Daudi cells with anti-CD19 antibodies does not induce apoptosis and has reduced tyrosine phosphorylation and SHP-1 recruitment to CEACAM1. Thus, similar to its function in T cells, CEACAM1 may act as an inhibitory B cell coreceptor, most likely through recruitment of SHP-1 and inhibition of a PI3K-promoted activation pathway. Activation of B cells by anti-sIgM or anti-CD19 antibodies also leads to cell aggregation that is promoted by CEACAM1, also in a PI3K-dependent manner.
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Affiliation(s)
- Elizabeth O Lobo
- Division of Immunology, Beckman Research Institute at City of Hope, Duarte, CA 91010, USA
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28
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Sialylated multivalent antigens engage CD22 in trans and inhibit B cell activation. Proc Natl Acad Sci U S A 2009; 106:2500-5. [PMID: 19202057 DOI: 10.1073/pnas.0807207106] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CD22 is an inhibitory coreceptor on the surface of B cells that attenuates B cell antigen receptor (BCR) signaling and, therefore, B cell activation. Elucidating the molecular mechanisms underlying the inhibitory activity of CD22 is complicated by the ubiquity of CD22 ligands. Although antigens can display CD22 ligands, the receptor is known to bind to sialylated glycoproteins on the cell surface. The propinquity of CD22 and cell-surface glycoprotein ligands has led to the conclusion that the inhibitory properties of the receptor are due to cis interactions. Here, we examine the functional consequences of trans interactions by employing sialylated multivalent antigens that can engage both CD22 and the BCR. Exposure of B cells to sialylated antigens results in the inhibition of key steps in BCR signaling. These results reveal that antigens bearing CD22 ligands are powerful suppressors of B cell activation. The ability of sialylated antigens to inhibit BCR signaling through trans CD22 interactions reveals a previously unrecognized role for the Siglec-family of receptors as modulators of immune signaling.
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Li DHH, Winslow MM, Cao TM, Chen AH, Davis CR, Mellins ED, Utz PJ, Crabtree GR, Parnes JR. Modulation of peripheral B cell tolerance by CD72 in a murine model. ACTA ACUST UNITED AC 2008; 58:3192-204. [PMID: 18821699 DOI: 10.1002/art.23812] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE B cells play a dominant role in the pathogenesis of several autoimmune diseases, including systemic lupus erythematosus. It is not well understood how B cell signaling contributes to autoantibody production. The goal of this study was to elucidate the role of CD72 in modulating B cell receptor (BCR)-mediated tolerogenic signaling and peripheral B cell tolerance. METHODS A mouse model utilizing hen egg lysozyme (HEL) "anergic" B cells was studied. CD72-deficient mice carrying the BCR-specific IgHEL and/or soluble HEL (sHEL) transgenes were generated by breeding IgHEL-transgenic MD4 mice and/or sHEL-transgenic ML5 mice with congenic, CD72-deficient C57BL/6J mice. Normal and anergic B cells were isolated for analyses of B cell signaling. Aged wild-type and CD72-deficient mice were also examined for autoimmune phenomena. RESULTS In the absence of CD72, anergic B cells inappropriately proliferated and survived in response to stimulation with self antigen. Biochemical analyses indicated that in anergic B cells, CD72 dominantly down-regulated BCR signaling to limit the antigen-induced elevation in [Ca2+]i and the activation of NFATc1, NF-kappaB, MAPK, and Akt. Mechanistically, CD72 was associated with, and regulated, the molecular adaptor Cbl-b in anergic B cells, suggesting that Cbl-b may play a role in mediating the negative effects of CD72 on BCR signaling. Moreover, in aged CD72-deficient mice, spontaneous production of antinuclear and anti-double-stranded DNA autoantibodies and features of lupus-like autoimmune disease were observed. CONCLUSION CD72 is required to maintain B cell anergy and functions as a regulator of peripheral B cell tolerance. Thus, altered CD72 expression may play a role during the development of systemic lupus erythematosus.
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30
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Cady CT, Rice JS, Ott VL, Cambier JC. Regulation of hematopoietic cell function by inhibitory immunoglobulin G receptors and their inositol lipid phosphatase effectors. Immunol Rev 2008; 224:44-57. [PMID: 18759919 DOI: 10.1111/j.1600-065x.2008.00663.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Numerous autoimmune and inflammatory disorders stem from the dysregulation of hematopoietic cell activation. The activity of inositol lipid and protein tyrosine phosphatases, and the receptors that recruit them, is critical for prevention of these disorders. Balanced signaling by inhibitory and activating receptors is now recognized to be an important factor in tuning cell function and inflammatory potential. In this review, we provide an overview of current knowledge of membrane proximal events in signaling by inhibitory/regulatory receptors focusing on structural and functional characteristics of receptors and their effectors Src homology 2 (SH2) domain-containing tyrosine phosphatase 1 and SH2 domain-containing inositol 5-phosphatase-1. We review use of new strategies to identify novel regulatory receptors and effectors. Finally, we discuss complementary actions of paired inhibitory and activating receptors, using Fc gammaRIIA and Fc gammaRIIB regulation human basophil activation as a prototype.
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Affiliation(s)
- Carol T Cady
- Department of Immunology, University of Colorado Denver School of Medicine, Denver, CO, USA
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31
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Xu J, Lu S, Tao J, Zhou Z, Chen Z, Huang Y, Yang R. CD72 polymorphism associated with child-onset of idiopathic thrombocytopenic purpura in Chinese patients. J Clin Immunol 2008; 28:214-9. [PMID: 18071878 DOI: 10.1007/s10875-007-9158-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Accepted: 11/21/2007] [Indexed: 11/30/2022]
Abstract
Idiopathic thrombocytopenic purpura (ITP) is a disease putatively relating to abnormal immune function and auto-antiplatelet immunoglobulin. We examined whether polymorphism of CD72, an inhibitory receptor of B cells, affect the susceptibility to ITP, or associated with the clinical characteristics of ITP. A case-control study was carried out in 206 Chinese ITP patients and 169 healthy controls. The detection of variable number of tandem repeats in CD72 intron 8 was performed by polymerase chain reaction and subsequent analysis with polyacrylamide gel electrophoresis. We did not find direct association between CD72 genotypes and susceptibility to ITP. The haplotype that contained one repeat of 13 nucleotides in intron 8 (designated as *1, and haplotype containing two repeat of 13 nucleotides in intron 8 is designated as *2) was significantly associated with early first onset age (< or = 14) in ITP patients (P = 0.03). ITP patients with CD72*1\*1 and *1\*2 genotype had a 3.09-fold [95% confidence interval (CI), 1.32-7.25] and 1.98-fold (95% CI, 0.92-4.25) increased risk of appearing ITP manifestation at their childhood respectively. The haplotype CD72*1 is apparently a risk allele, whereas CD72*2 a protective allele for child-onset of ITP disease.
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MESH Headings
- Acute Disease
- Adolescent
- Adult
- Age of Onset
- Antigens, CD/genetics
- Antigens, Differentiation, B-Lymphocyte/genetics
- Autoantibodies/biosynthesis
- Case-Control Studies
- Child
- Child, Preschool
- China/epidemiology
- Chronic Disease
- Cytokines/biosynthesis
- Female
- Genetic Predisposition to Disease
- Humans
- Infant
- Male
- Middle Aged
- Polymorphism, Genetic
- Purpura, Thrombocytopenic, Idiopathic/diagnosis
- Purpura, Thrombocytopenic, Idiopathic/epidemiology
- Purpura, Thrombocytopenic, Idiopathic/genetics
- Purpura, Thrombocytopenic, Idiopathic/immunology
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Affiliation(s)
- Jianhui Xu
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 288 Nanjing Road, Tianjin 300020, China
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32
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Onodera T, Poe JC, Tedder TF, Tsubata T. CD22 regulates time course of both B cell division and antibody response. THE JOURNAL OF IMMUNOLOGY 2008; 180:907-13. [PMID: 18178830 DOI: 10.4049/jimmunol.180.2.907] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Because pathogens induce infectious symptoms in a time-dependent manner, a rapid immune response is beneficial for defending hosts from pathogens, especially those inducing acute infectious diseases. However, it is largely unknown how the time course of immune responses is regulated. In this study, we demonstrate that B cells deficient in the inhibitory coreceptor CD22 undergo accelerated cell division after Ag stimulation, resulting in rapid generation of plasma cells and Ab production. This finding indicates that CD22 regulates the time course of B cell responses and suggests that CD22 is a good target to shorten the time required for Ab production, thereby augmenting host defense against acute infectious diseases as "universal vaccination."
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Affiliation(s)
- Taishi Onodera
- Laboratory of Immunology, School of Biomedical Science, Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Japan
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33
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Adachi T, Tsubata T. FRET-based Ca2+ measurement in B lymphocyte by flow cytometry and confocal microscopy. Biochem Biophys Res Commun 2008; 367:377-82. [DOI: 10.1016/j.bbrc.2007.12.142] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 12/20/2007] [Indexed: 11/29/2022]
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34
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Conformational plasticity and navigation of signaling proteins in antigen-activated B lymphocytes. Adv Immunol 2008; 97:251-81. [PMID: 18501772 DOI: 10.1016/s0065-2776(08)00005-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Over the past two decades our view of the B cell antigen receptor (BCR) has fundamentally changed. Being initially regarded as a mute antibody orphan of the B cell surface, the BCR turned out to be a complex multimolecular machine monitoring almost all stages of B cell development, selection, and activation through a plethora of ubiquitously and cell-type-specific effector proteins. A comprehensive understanding of the many BCR signaling facets is still out but a few common biochemical principles outlined in this review operate at the level of receptor activation and orchestrate specific wiring of intracellular transducer cascades. First, initiation and processing of antigen-induced signal transduction relies on transient conformational changes in the signaling proteins to trigger their physical interaction with downstream elements. Second, this dynamic assembly of signalosomes occurs at distinct subcellular locations, most prominently the plasma membrane, which requires dynamic relocalization of one or more of the engaged molecules. For both, precise complex formation and efficient subcellular targeting, B cell signaling components are equipped with a variety of protein interaction domains. Here we provide an overview on how these simple rules are applied by a limited number of transmembrane and cytosolic proteins to convert BCR ligation into Ca(2+) mobilization and Ras activation in an adjustable manner.
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35
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36
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Interdomain A is crucial for ITAM-dependent and -independent regulation of Syk. Biochem Biophys Res Commun 2007; 364:111-7. [PMID: 17936247 DOI: 10.1016/j.bbrc.2007.09.100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 09/25/2007] [Indexed: 11/21/2022]
Abstract
Non-receptor type protein tyrosine kinase (PTK) Syk is essential for the signaling via the B cell antigen receptor (BCR). Upon BCR crosslinking, Syk is recruited via its tandem SH2 domains to tyrosine-phosphorylated Ig-alpha/Ig-beta constituting components of BCR, and is then activated. The interdomain A lying between the two SH2 domains is highly conserved among different species of Syk and between Syk and ZAP-70. The mutant Syk carrying a deletion in the interdomain A (Delta140-159) became phosphorylated regardless of BCR ligation and did not induce Ca2+ mobilization upon crosslinking of BCR. Furthermore, in vitro binding assay revealed that deletion of a part of the interdomain A abolished its binding activity to phosphorylated Ig-alpha/Ig-beta. These results indicate that the interdomain A of Syk is required for activation of Syk by binding to the phosphorylated Ig-alpha/Ig-beta upon BCR ligation and inhibition of spontaneous activation at the resting state.
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37
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Engelke M, Engels N, Dittmann K, Stork B, Wienands J. Ca(2+) signaling in antigen receptor-activated B lymphocytes. Immunol Rev 2007; 218:235-46. [PMID: 17624956 DOI: 10.1111/j.1600-065x.2007.00539.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
B cells respond to antigen stimulation with mobilization of the Ca(2+) second messenger in two phases operated by two distinct sets of effector proteins. First, an antigen receptor-specific Ca(2+) initiation complex is assembled, activated, and targeted to the plasma membrane to trigger the transient release of Ca(2+) from intracellular stores of the endoplasmic reticulum. Second, more ubiquitously expressed Ca(2+) channels of the plasma membrane are opened to allow for sustained Ca(2+) influx from the extracellular medium. Depending on the developmental stage of the B cell, the kinetics and profile of the two phases are adjusted at multiple levels of positive and negative regulation. A molecular basis for the Ca(2+) signaling plasticity is provided by cytosolic and transmembrane adapter proteins. They act as signal organizers, which control enzyme/substrate interactions by directing the different signaling modules into specific subcellular compartments. These arrangements orchestrate a graduated activation of Ca(2+)-sensitive downstream pathways, which ultimately determine appropriate cellular responses, namely elimination of autoreactive B cells or proliferation and differentiation of immunocompetent B cells into antibody-secreting plasma cells.
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Affiliation(s)
- Michael Engelke
- Georg August University of Göttingen, Institute of Cellular and Molecular Immunology, Göttingen, Germany
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38
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Haga CL, Ehrhardt GRA, Boohaker RJ, Davis RS, Cooper MD. Fc receptor-like 5 inhibits B cell activation via SHP-1 tyrosine phosphatase recruitment. Proc Natl Acad Sci U S A 2007; 104:9770-5. [PMID: 17522256 PMCID: PMC1887609 DOI: 10.1073/pnas.0703354104] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Fc receptor-like protein 5 (FCRL5) on B cells has both an immunoreceptor tyrosine-based activation motif (ITAM)-like sequence and two consensus immunoreceptor tyrosine-based inhibitory motifs (ITIM) in its cytoplasmic region. To evaluate its signaling potential, we expressed constructs for chimeric molecules composed of the cytoplasmic region of FCRL5 and the extracellular and transmembrane regions of the IgG Fc receptor FcgammaRIIB in a B cell line lacking an endogenous Fc receptor. Coligation of this fusion protein with the B cell receptor (BCR) inhibited BCR-mediated calcium mobilization, intracellular tyrosine phosphorylation, and Erk kinase activation. Our mutational analysis indicated that, whereas tyrosines in both the inhibitory and activation motifs are phosphorylated after ligation, only those in ITIMs influence BCR-mediated signaling. This FCRL5 inhibitory effect was mediated through dual ITIM recruitment of the SH2-containing protein tyrosine phosphatase, SHP-1, which in turn dephosphorylates the ITAM-based tyrosines in BCR Igalpha/Igbeta heterodimers. An FCRL5 inhibitory effect on BCR signaling was likewise demonstrable for primary B cells. Although its ligand is presently unknown, we conclude that FCRL5 has the functional potential to serve as an inhibitory coreceptor on mature B cells in humans.
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MESH Headings
- Animals
- Antibodies, Monoclonal
- B-Lymphocytes/immunology
- Blotting, Western
- Calcium/metabolism
- Cell Line
- DNA Mutational Analysis
- Flow Cytometry
- Immunoprecipitation
- Lymphocyte Activation/immunology
- Mice
- Mice, Inbred BALB C
- Phosphorylation
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/immunology
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/metabolism
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Fc/genetics
- Receptors, Fc/immunology
- Receptors, Fc/metabolism
- Receptors, IgG/genetics
- Receptors, IgG/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction/immunology
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Affiliation(s)
| | | | | | - Randall S. Davis
- Divisions of *Developmental and Clinical Immunology and
- Hematology/Oncology and
- Departments of Biochemistry and Molecular Genetics
- Medicine
- Microbiology, and
| | - Max D. Cooper
- Divisions of *Developmental and Clinical Immunology and
- Medicine
- Microbiology, and
- Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35294
- **To whom correspondence should be addressed. E-mail:
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39
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Stork B, Neumann K, Goldbeck I, Alers S, Kähne T, Naumann M, Engelke M, Wienands J. Subcellular localization of Grb2 by the adaptor protein Dok-3 restricts the intensity of Ca2+ signaling in B cells. EMBO J 2007; 26:1140-9. [PMID: 17290227 PMCID: PMC1852829 DOI: 10.1038/sj.emboj.7601557] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 12/19/2006] [Indexed: 01/19/2023] Open
Abstract
Spatial and temporal modulation of intracellular Ca2+ fluxes controls the cellular response of B lymphocytes to antigen stimulation. Herein, we identify the hematopoietic adaptor protein Dok-3 (downstream of kinase-3) as a key component of negative feedback regulation in Ca2+ signaling from the B-cell antigen receptor. Dok-3 localizes at the inner leaflet of the plasma membrane and is a major substrate for activated Src family kinase Lyn. Phosphorylated Dok-3 inhibits antigen receptor-induced Ca2+ elevation by recruiting cytosolic Grb2, which acts at this location as a negative regulator of Bruton's tyrosine kinase. This leads to diminished activation of phospholipase C-gamma2 and reduced production of soluble inositol trisphosphate. Hence, the Dok-3/Grb2 module is a membrane-associated signaling organizer, which orchestrates the interaction efficiency of Ca2+-mobilizing enzymes.
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Affiliation(s)
- Björn Stork
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
| | - Konstantin Neumann
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
| | - Ingo Goldbeck
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
| | - Sebastian Alers
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
| | - Thilo Kähne
- Institute of Experimental Internal Medicine, Otto von Guericke University, Magdeburg, Germany
| | - Michael Naumann
- Institute of Experimental Internal Medicine, Otto von Guericke University, Magdeburg, Germany
| | - Michael Engelke
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
| | - Jürgen Wienands
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Göttingen, Germany
- Institute of Cellular and Molecular Immunology, Georg August University of Göttingen, Humboldtallee 34, 37073 Göttingen, Germany. Tel.: +49 (0)551 39 5812; Fax: +49 (0)551 39 5843, E-mail:
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40
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Abstract
The semaphorin family consists of soluble and membrane-bound proteins originally identified as axonal guidance cues functioning during neuronal development. However, it is becoming increasingly clear that semaphorins play diverse roles in organogenesis, vascular growth, and tumor progression. In addition, emerging evidence indicates that several semaphorins, called "immune semaphorins," play crucial roles also during immune responses. Extensive studies on the immune semaphorins have revealed not only parallels but also differences in the semaphorin functions between the immune and nervous systems, providing unexpected but meaningful insights into the biological activities of these molecules. This chapter focuses on our current understanding of the roles of semaphorins and their receptors in the immune system.
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Affiliation(s)
- Hitoshi Kikutani
- Department of Molecular Immunology and CREST Program of JST, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 5650871, Japan
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41
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Yamashita Y, Phee H, Tudor KSRS, Rossi MID, Parnes JR, Coggeshall KM, Kincade PW. A unique CD72 epitope suggests a potential interaction with Fc gamma RII/CD32 on B lineage lymphocytes. Hybridoma (Larchmt) 2006; 25:107-14. [PMID: 16796456 DOI: 10.1089/hyb.2006.25.107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
It has long been known that ligation of the transmembrane CD72 glycoprotein delivers signals to B lymphocytes, with the outcome depending on context. Of particular interest is its ability to function as a counter-receptor/ ligand for the CD100 semaphorin protein. We have now obtained evidence that CD72 physically interacts on the lymphocyte membrane with Fcgamma receptor II (CD32). The association was first revealed with a new monoclonal antibody that recognizes polymorphic determinants on murine CD72. Although the specificity for CD72 was clear from immunoblotting, transfection and other experiments, staining with this reagent was inhibited when cells were pretreated with an Fc receptor-blocking antibody (CD16/CD32 specific). Furthermore, confocal microscopy revealed that the two molecules co-distributed on viable B cells. We also used the antibody to determine when CD72 becomes available to maturing lymphocytes. The marker is first acquired as large pre-B cells and enter the IL-7 independent phase of maturation within bone marrow. Subsequent interactions between CD72 and CD32 may cooperatively deliver negative signals that modulate humoral immune responses.
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MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/immunology
- Antigens, Differentiation, B-Lymphocyte/metabolism
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- COS Cells
- Cell Line, Tumor
- Cell Lineage/immunology
- Chlorocebus aethiops
- Epitopes, B-Lymphocyte/immunology
- Epitopes, B-Lymphocyte/metabolism
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/immunology
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Rats
- Rats, Wistar
- Receptors, IgG/metabolism
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Affiliation(s)
- Yoshio Yamashita
- Immunobiology & Cancer Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA
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42
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Li DH, Tung JW, Tarner IH, Snow AL, Yukinari T, Ngernmaneepothong R, Martinez OM, Parnes JR. CD72 down-modulates BCR-induced signal transduction and diminishes survival in primary mature B lymphocytes. THE JOURNAL OF IMMUNOLOGY 2006; 176:5321-8. [PMID: 16621999 DOI: 10.4049/jimmunol.176.9.5321] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
CD72, a 45-kDa type II transmembrane glycoprotein carrying an ITIM motif, is believed to be an inhibitory coreceptor of the BCR. Mature B cells lacking CD72 show enhanced Ca(2+) mobilization and are hyperproliferative in response to BCR ligation. However, the signal transduction pathways downstream of BCR signaling that transmit the inhibitory effect of CD72 in mature B cells remain unknown. To address this question, we used hen egg lysozyme-specific BCR transgenic mice to elucidate the differential cell signaling between wild-type and CD72-deficient B cells in response to hen egg lysozyme Ag stimulation. Our results demonstrate that CD72 predominantly down-regulates the major signal transduction pathways downstream of the BCR, including NF-AT, NF-kappaB, ERK, JNK, p38-MAPK, and PI3K/Akt in mature B cells. CD72 ligation with anti-CD72 Ab (K10.6), which mimics the binding of CD100 (a natural ligand for CD72) to release the inhibitory function of CD72, augments cell proliferation, Ca(2+) flux, IkappaBalpha activation, and ERK MAPK activity upon Ag stimulation in wild-type B cells. In addition, we show direct evidence that CD72 promotes cell cycle arrest and apoptosis after Ag stimulation in mature B cells. Taken together, our findings conclude that CD72 plays a dominant role as a negative regulator of BCR signaling in primary mature B lymphocytes.
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Affiliation(s)
- Daniel H Li
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, USA
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43
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Imhof D, Wavreille AS, May A, Zacharias M, Tridandapani S, Pei D. Sequence specificity of SHP-1 and SHP-2 Src homology 2 domains. Critical roles of residues beyond the pY+3 position. J Biol Chem 2006; 281:20271-82. [PMID: 16702225 DOI: 10.1074/jbc.m601047200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A combinatorial phosphotyrosyl (pY) peptide library was screened to determine the amino acid preferences at the pY+4 to pY+6 positions for the four SH2 domains of protein-tyrosine phosphatases SHP-1 and SHP-2. Individual binding sequences selected from the library were resynthesized and their binding affinities and specificities to various SH2 domains were further evaluated by SPR studies, stimulation of SHP-1 and SHP-2 phosphatase activity, and in vitro pulldown assays. These studies reveal that binding of a pY peptide to the N-SH2 domain of SHP-2 is greatly enhanced by a large hydrophobic residue (Trp, Tyr, Met, or Phe) at the pY+4 and/or pY+5 positions, whereas binding to SHP-1 N-SH2 domain is enhanced by either hydrophobic or positively charged residues (Arg, Lys, or His) at these positions. Similar residues at the pY+4 to pY+6 positions are also preferred by SHP-1 and SHP-2 C-SH2 domains, although their influence on the overall binding affinities is much smaller compared with the N-SH2 domains. A structural model was generated to qualitatively interpret the contribution of the pY+4 and pY+5 residues to the overall binding affinity. Examination of pY motifs from known SHP-1 and SHP-2-binding proteins shows that many of the pY motifs contain a hydrophobic or positively charged residue(s) at the pY+4 and pY+5 positions.
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Affiliation(s)
- Diana Imhof
- Department of Chemistry, Ohio State University, Columbus, Ohio 43210, USA
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44
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Fujiwara N, Hidano S, Mamada H, Ogasawara K, Kitamura D, Cooper MD, Hozumi N, Chen CLH, Goitsuka R. A novel avian homologue of CD72, chB1r, down modulates BCR-mediated activation signals. Int Immunol 2006; 18:775-83. [PMID: 16581823 DOI: 10.1093/intimm/dxl014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The avian B cell differentiation antigen chB1 is a C-type lectin membrane protein most homologous to mammalian CD72. Here, we report a new chB1-related gene, chB1r, that is located 18 kb away the chB1 gene. The cytoplasmic domain of chB1r protein contains two immunoreceptor tyrosine-based inhibitory motifs (ITIMs: ITIM1 and 2), which are identical to those found in CD72, whereas chB1 lacks the second ITIM2. Although chB1 expression is restricted to the bursa and an immature B cell line, chB1r is highly expressed in the bursa, spleen and both immature and mature B cell lines, a pattern that parallels CD72 expression. SHP-1 and Grb2 interact with phosphorylated tyrosine residues within chB1r ITIM1 and ITIM2, respectively. By contrast, ITIM1 of chB1 does not interact with SHP-1. Functional characterization using chB1r/chB1 double-deficient DT40 B cells demonstrated that ITIM1 in chB1r transduces a negative signal for BCR-mediated nuclear factor of activated T cells (NF-AT) activation and that ITIM2 attenuates this negative signal. This study has established chB1r as the genuine avian homologue of mammalian CD72, and revealed an opposing role for the two ITIMs through binding with SHP-1 and Grb2 for regulation of BCR-mediated NF-AT activation.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, Differentiation, B-Lymphocyte/biosynthesis
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/immunology
- B-Lymphocytes/immunology
- COS Cells
- Chickens
- Chlorocebus aethiops
- GRB2 Adaptor Protein/genetics
- GRB2 Adaptor Protein/immunology
- GRB2 Adaptor Protein/pharmacology
- Lectins, C-Type/genetics
- Lectins, C-Type/immunology
- Molecular Sequence Data
- NFATC Transcription Factors/immunology
- NFATC Transcription Factors/metabolism
- Receptors, Antigen, B-Cell/immunology
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Affiliation(s)
- Naruyoshi Fujiwara
- Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda, Chiba 278-0022, Japan
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45
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Tolar P, Sohn HW, Pierce SK. The initiation of antigen-induced B cell antigen receptor signaling viewed in living cells by fluorescence resonance energy transfer. Nat Immunol 2005; 6:1168-76. [PMID: 16200067 DOI: 10.1038/ni1262] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Accepted: 09/12/2005] [Indexed: 11/09/2022]
Abstract
Binding of antigen to the B cell antigen receptor (BCR) triggers signaling that ultimately leads to B cell activation. Using quantitative fluorescence resonance energy transfer imaging, we provide evidence here that the BCR is a monomer on the surface of resting cells. Binding of multivalent antigen clustered the BCR, resulting in the simultaneous phosphorylation of and a conformational change in the BCR cytoplasmic domains from a closed to an open form. Notably, the open conformation required immunoreceptor tyrosine-activation motif and continuous Src family kinase activity but not binding of the kinase Syk. Thus, the initiation of BCR signaling is a very dynamic process accompanied by reversible conformational changes induced by Src family kinase activity.
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Affiliation(s)
- Pavel Tolar
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA
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Abstract
The random and inherently imprecise process of V(D)J recombination is the foundation for generation of the B-cell receptor (BCR). Signals must be generated to trigger selective processes that retain cells expressing a functional BCR, and these signals must be antigen-independent to insure an unbiased and diverse pool of newly formed B cells. Moreover, BCR expression, and presumably signaling, is essential for the continued survival of the B cell. Although BCR signaling is generally thought to depend upon ligand-induced aggregation, recent studies argue that some aspects of BCR signaling occur independently of antigen, and, furthermore, these non-induced or 'tonic' signals are linked to specific cellular processes operating at multiple stages of B-cell development. The potential co-existence of tonic and induced signaling suggests a unique aspect of BCR complexes, or at least an aspect of receptors that has previously been under-appreciated.
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Affiliation(s)
- John G Monroe
- University of Pennsylvania School of Medicine, 421 Curie Boulevard, Philadelphia, Pennsylvania 191104, USA.
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Stork B, Engelke M, Frey J, Horejsí V, Hamm-Baarke A, Schraven B, Kurosaki T, Wienands J. Grb2 and the Non-T Cell Activation Linker NTAL Constitute a Ca2+-Regulating Signal Circuit in B Lymphocytes. Immunity 2004; 21:681-91. [PMID: 15539154 DOI: 10.1016/j.immuni.2004.09.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Revised: 09/07/2004] [Accepted: 09/22/2004] [Indexed: 01/23/2023]
Abstract
Activation of the B cell antigen receptor triggers phosphorylation of cytoplasmic and transmembrane adaptor proteins such as SLP-65 and NTAL, respectively. Specific phosphoacceptor sites in SLP-65 serve as docking sites for Ca(2+)-mobilizing enzymes Btk and PLC-gamma2. Phosphorylated NTAL recruits the Grb2 linker, but downstream signaling cascades are unclear. We now show that receptor-induced tyrosine phosphorylation of NTAL and concomitant Grb2 complex formation critically modulate the Ca(2+) response without affecting SLP-65 and PLC-gamma2 phosphorylation. Grb2 turned out to play a negative regulatory role, which appears to be eliminated upon binding to NTAL. This allows for a sustained release of intracellular Ca(2+) and is mandatory for subsequent entry of Ca(2+) from extracellular sources. Thus, elevation of Ca(2+) is regulated by at least two signaling modules, the B cell-specific Ca(2+) initiation complex comprising SLP-65, Btk, and PLC-gamma2 and the more ubiquitously expressed NTAL/Grb2 complex, which acts as an amplifier by switching off inhibitory elements.
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Affiliation(s)
- Björn Stork
- Department of Biochemistry and Molecular Immunology, University of Bielefeld, 33615 Bielefeld, Germany
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Nitschke L, Tsubata T. Molecular interactions regulate BCR signal inhibition by CD22 and CD72. Trends Immunol 2004; 25:543-50. [DOI: 10.1016/j.it.2004.08.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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49
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Affiliation(s)
- Michael Reth
- Department of Molecular Immunology, Institute for Biology III, Albert-Ludwigs-University of Freiburg and Max-Planck-Institut for Immunobiology, 79108 Freiburg, Germany.
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Ehrhardt GRA, Davis RS, Hsu JT, Leu CM, Ehrhardt A, Cooper MD. The inhibitory potential of Fc receptor homolog 4 on memory B cells. Proc Natl Acad Sci U S A 2003; 100:13489-94. [PMID: 14597715 PMCID: PMC263841 DOI: 10.1073/pnas.1935944100] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fc receptor homolog 4 (FcRH4) is a B cell-specific member of the recently identified family of FcRHs whose intracellular domain contains three potential immunoreceptor tyrosine-based inhibitory motifs (ITIMs). The signaling potential of this receptor, shown here to be preferentially expressed by memory B cells, was compared with the inhibitory receptor FcgammaRIIb in B cells expressing either WT FcgammaRIIb or chimeric proteins in which the intracellular domain of FcRH4 was fused to the transmembrane and extracellular domains of FcgammaRIIb. Coligation of the FcgammaRIIb/FcRH4 chimeric protein with the B cell receptor (BCR) led to tyrosine phosphorylation of the two membrane-distal tyrosines and profound inhibition of BCR-mediated calcium mobilization, whole cell tyrosine phosphorylation, and mitogen-activated protein (MAP)-kinase activation. Mutational analysis of the FcRH4 cytoplasmic region indicated that the two membrane-distal ITIMs are essential for this inhibitory potential. Phosphopeptides corresponding to these ITIMs could bind the Src homology 2 (SH2) domain-containing tyrosine phosphatases SHP-1 and SHP-2, which associated with the WT FcRH4 and with mutants having inhibitory capability. These findings indicate the potential for FcRH4 to abort B cell receptor signaling by recruiting SHP-1 and SHP-2 to its two membrane distal ITIMs.
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Affiliation(s)
- Gotz R A Ehrhardt
- Divisions of Developmental and Clinical Immunology and Hematology/Oncology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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