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Emerging phagocytosis checkpoints in cancer immunotherapy. Signal Transduct Target Ther 2023; 8:104. [PMID: 36882399 PMCID: PMC9990587 DOI: 10.1038/s41392-023-01365-z] [Citation(s) in RCA: 134] [Impact Index Per Article: 67.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/31/2023] [Accepted: 02/14/2023] [Indexed: 03/09/2023] Open
Abstract
Cancer immunotherapy, mainly including immune checkpoints-targeted therapy and the adoptive transfer of engineered immune cells, has revolutionized the oncology landscape as it utilizes patients' own immune systems in combating the cancer cells. Cancer cells escape immune surveillance by hijacking the corresponding inhibitory pathways via overexpressing checkpoint genes. Phagocytosis checkpoints, such as CD47, CD24, MHC-I, PD-L1, STC-1 and GD2, have emerged as essential checkpoints for cancer immunotherapy by functioning as "don't eat me" signals or interacting with "eat me" signals to suppress immune responses. Phagocytosis checkpoints link innate immunity and adaptive immunity in cancer immunotherapy. Genetic ablation of these phagocytosis checkpoints, as well as blockade of their signaling pathways, robustly augments phagocytosis and reduces tumor size. Among all phagocytosis checkpoints, CD47 is the most thoroughly studied and has emerged as a rising star among targets for cancer treatment. CD47-targeting antibodies and inhibitors have been investigated in various preclinical and clinical trials. However, anemia and thrombocytopenia appear to be formidable challenges since CD47 is ubiquitously expressed on erythrocytes. Here, we review the reported phagocytosis checkpoints by discussing their mechanisms and functions in cancer immunotherapy, highlight clinical progress in targeting these checkpoints and discuss challenges and potential solutions to smooth the way for combination immunotherapeutic strategies that involve both innate and adaptive immune responses.
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2
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Huang Z, Chen K, Yang X, Cui H, Wu Y, Wang Y, Xia X, Sun H, Xie W, Li H, Zheng R, Sun Y, Han D, Shang H. Spatial metabolomics reveal mechanisms of dexamethasone against pediatric pneumonia. J Pharm Biomed Anal 2023; 229:115369. [PMID: 36996615 DOI: 10.1016/j.jpba.2023.115369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/20/2023] [Accepted: 03/25/2023] [Indexed: 03/29/2023]
Abstract
Currently, drugs are limited to treating pediatric pneumonia in clinical practice. It is urgent to find one new precise prevention and control therapy. The dynamically changing biomarkers during the development of pediatric pneumonia could help diagnose this disease, determine its severity, assess the risk of future events, and guide its treatment. Dexamethasone has been recognized as an effective agent with anti-inflammatory activity. However, its mechanisms against pediatric pneumonia remain unclear. In this study, spatial metabolomics was used to reveal the potential and characteristics of dexamethasone. Specifically, bioinformatics was first applied to find the critical biomarkers of differential expression in pediatric pneumonia. Subsequently, Desorption Electrospray Ionization mass spectrometry imaging-based metabolomics screened the differential metabolites affected by dexamethasone. Then, a gene-metabolite interaction network was built to mark functional correlation pathways for exploring integrated information and core biomarkers related to the pathogenesis and etiology of pediatric pneumonia. Further, these were validated by molecular biology and targeted metabolomics. As a result, genes of Cluster of Differentiation19, Fc fragment of IgG receptor IIb, Cluster of Differentiation 22, B-cell linker, Cluster of Differentiation 79B and metabolites of Triethanolamine, Lysophosphatidylcholine(18:1(9Z)), Phosphatidylcholine(16:0/16:0), phosphatidylethanolamine(O-18:1(1Z)/20:4(5Z,8Z,11Z,14Z)) were identified as the critical biomarkers in pediatric pneumonia. B cell receptor signaling pathway and glycerophospholipid metabolism were integrally analyzed as the main pathways of these biomarkers. The above data were illustrated using a Lipopolysaccharides-induced lung injury juvenile rat model. This work will provide evidence for the precise treatment of pediatric pneumonia.
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Schwarz JJ, Grundmann L, Kokot T, Kläsener K, Fotteler S, Medgyesi D, Köhn M, Reth M, Warscheid B. Quantitative proteomics identifies PTP1B as modulator of B cell antigen receptor signaling. Life Sci Alliance 2021; 4:4/11/e202101084. [PMID: 34526379 PMCID: PMC8473724 DOI: 10.26508/lsa.202101084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/28/2021] [Accepted: 09/01/2021] [Indexed: 11/24/2022] Open
Abstract
This study analyses the function of the protein tyrosine phosphatase 1B identifying its binding partners and dephosphorylation targets for modulating B cell antigen receptor signaling. B cell antigen receptor (BCR) signaling is initiated by protein kinases and limited by counteracting phosphatases that currently are less well studied in their regulation of BCR signaling. Here, we used the B cell line Ramos to identify and quantify human B cell signaling components. Specifically, a protein tyrosine phosphatase profiling revealed a high expression of the protein tyrosine phosphatase 1B (PTP1B) in Ramos and human naïve B cells. The loss of PTP1B leads to increased B cell activation. Through substrate trapping in combination with quantitative mass spectrometry, we identified 22 putative substrates or interactors of PTP1B. We validated Igα, CD22, PLCγ1/2, CBL, BCAP, and APLP2 as specific substrates of PTP1B in Ramos B cells. The tyrosine kinase BTK and the two adaptor proteins GRB2 and VAV1 were identified as direct binding partners and potential substrates of PTP1B. We showed that PTP1B dephosphorylates the inhibitory receptor protein CD22 at phosphotyrosine 807. We conclude that PTP1B negatively modulates BCR signaling by dephosphorylating distinct phosphotyrosines in B cell-specific receptor proteins and various downstream signaling components.
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Affiliation(s)
- Jennifer J Schwarz
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Lorenz Grundmann
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Thomas Kokot
- Integrative Signalling Research, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Kathrin Kläsener
- Department for Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Sandra Fotteler
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - David Medgyesi
- Department for Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Maja Köhn
- Integrative Signalling Research, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Michael Reth
- Department for Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Bettina Warscheid
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany .,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
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Li J, Yin W, Jing Y, Kang D, Yang L, Cheng J, Yu Z, Peng Z, Li X, Wen Y, Sun X, Ren B, Liu C. The Coordination Between B Cell Receptor Signaling and the Actin Cytoskeleton During B Cell Activation. Front Immunol 2019; 9:3096. [PMID: 30687315 PMCID: PMC6333714 DOI: 10.3389/fimmu.2018.03096] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 12/13/2018] [Indexed: 01/27/2023] Open
Abstract
B-cell activation plays a crucial part in the immune system and is initiated via interaction between the B cell receptor (BCR) and specific antigens. In recent years with the help of modern imaging techniques, it was found that the cortical actin cytoskeleton changes dramatically during B-cell activation. In this review, we discuss how actin-cytoskeleton reorganization regulates BCR signaling in different stages of B-cell activation, specifically when stimulated by antigens, and also how this reorganization is mediated by BCR signaling molecules. Abnormal BCR signaling is associated with the progression of lymphoma and immunological diseases including autoimmune disorders, and recent studies have proved that impaired actin cytoskeleton can devastate the normal activation of B cells. Therefore, to figure out the coordination between the actin cytoskeleton and BCR signaling may reveal an underlying mechanism of B-cell activation, which has potential for new treatments for B-cell associated diseases.
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Affiliation(s)
- Jingwen Li
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Yin
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yukai Jing
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Danqing Kang
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lu Yang
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiali Cheng
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ze Yu
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zican Peng
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xingbo Li
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yue Wen
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xizi Sun
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Boxu Ren
- Department of Immunology, School of Medicine, Yangtze University, Jingzhou, China
- Clinical Molecular Immunology Center, School of Medicine, Yangtze University, Jingzhou, China
| | - Chaohong Liu
- Department of Microbiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Chen J, Wang H, Xu WP, Wei SS, Li HJ, Mei YQ, Li YG, Wang YP. Besides an ITIM/SHP-1-dependent pathway, CD22 collaborates with Grb2 and plasma membrane calcium-ATPase in an ITIM/SHP-1-independent pathway of attenuation of Ca2+i signal in B cells. Oncotarget 2018; 7:56129-56146. [PMID: 27276708 PMCID: PMC5302901 DOI: 10.18632/oncotarget.9794] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/14/2016] [Indexed: 12/30/2022] Open
Abstract
CD22 is a surface immunoglobulin implicated in negative regulation of B cell receptor (BCR) signaling; particularly inhibiting intracellular Ca2+ (Ca2+i)signals. Its cytoplasmic tail contains six tyrosine residues (Y773/Y783/Y817/Y828/Y843/Y863, designated Y1~Y6 respectively), including three (Y2/5/6) lying within immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that serve to recruit the protein tyrosine phosphatase SHP-1 after BCR activation-induced phosphorylation. The mechanism of inhibiting Ca2+i by CD22 has been poorly understood. Previous study demonstrated that CD22 associated with plasma membrane calcium-ATPase (PMCA) and enhanced its activity (Chen, J. et al. Nat Immunol 2004;5:651-7). The association is dependent on BCR activation-induced cytoplasmic tyrosine phosphorylation, because CD22 with either all six tyrosines mutated to phenylalanines or cytoplasmic tail truncated loses its ability to associate with PMCA. However, which individual or a group of tyrosine residues determine the association and how CD22 and PMCA interacts, are still unclear. In this study, by using a series of CD22 tyrosine mutants, we found that ITIM Y2/5/6 accounts for 34.3~37.1% Ca2+i inhibition but is irrelevant for CD22/PMCA association. Non-ITIM Y4 and its YEND motif contribute to the remaining 69.4~71.7% Ca2+i inhibition and is the binding site for PMCA-associated Grb2. Grb2, independently of BCR cross-linking, is constitutively associated with and directly binds to PMCA in both chicken and human B cells. Knockout of Grb2 by CRISPR/Cas9 completely disrupted the CD22/PMCA association. Thus, our results demonstrate for the first time that in addition to previously-identified ITIM/SHP-1-dependent pathway, CD22 holds a major pathway of negative regulation of Ca2+i signal, which is ITIM/SHP-1-independent, but Y4/Grb2/PMCA-dependent.
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Affiliation(s)
- Jie Chen
- Department of Cardiology, Affiliated Xinhua Hospital, Shanghai Jiaotong University (SJTU) School of Medicine, Shanghai, China
| | - Hong Wang
- Department of Cardiology, Affiliated Xinhua Hospital, Shanghai Jiaotong University (SJTU) School of Medicine, Shanghai, China
| | - Wei-Ping Xu
- Department of Cardiology, Affiliated Xinhua Hospital, Shanghai Jiaotong University (SJTU) School of Medicine, Shanghai, China
| | - Si-Si Wei
- Department of Pediatrics, Affiliated Xinhua Hospital, Shanghai Jiaotong University (SJTU) School of Medicine, Shanghai, China
| | - Hui Joyce Li
- Department of Medicine, University of Massachusetts School of Medicine, Worcester, MA, USA
| | - Yun-Qing Mei
- Department of Cardio-Thoracic Surgery, Shanghai Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi-Gang Li
- Department of Cardiology, Affiliated Xinhua Hospital, Shanghai Jiaotong University (SJTU) School of Medicine, Shanghai, China
| | - Yue-Peng Wang
- Department of Cardiology, Affiliated Xinhua Hospital, Shanghai Jiaotong University (SJTU) School of Medicine, Shanghai, China
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6
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Abstract
Many Siglecs function as inhibitory receptors on innate and adaptive immune cells and may contribute to the attenuation of immune responses to tumors. Siglec 9 on neutrophils and Siglec 7 on NK cells are prominent examples of inhibitory Siglecs that can potentially dampen anti-tumor immunity. CD169 is a Siglec that may function as an adhesion molecule and a facilitator of the recognition and internalization of sialic acid decorated apoptotic bodies and exosomes derived from tumors. It can potentially contribute to both the attenuation as well as the facilitation of anti-tumor immunity. Siglecs have been best studied in the tumor context in animal models of cancer. Modulators of Siglec function are likely to be developed and investigated clinically in a cancer context over the next few years.
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Affiliation(s)
- Isabella Fraschilla
- Ragon Institute of MGH, MIT and Harvard, Harvard Medical School, Cambridge, MA, USA
| | - Shiv Pillai
- Ragon Institute of MGH, MIT and Harvard, Harvard Medical School, Cambridge, MA, USA
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7
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St-Pierre G, Pal S, Østergaard ME, Zhou T, Yu J, Tanowitz M, Seth PP, Hanessian S. Synthesis and biological evaluation of sialyl-oligonucleotide conjugates targeting leukocyte B trans-membranal receptor CD22 as delivery agents for nucleic acid drugs. Bioorg Med Chem 2016; 24:2397-2409. [PMID: 27117693 DOI: 10.1016/j.bmc.2016.03.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/16/2016] [Accepted: 03/27/2016] [Indexed: 01/27/2023]
Abstract
Antisense oligonucleotides (ASOs) modified with ligands which target cell surface receptors have the potential to significantly improve potency in the target tissue. This has recently been demonstrated using triantennary N-acetyl d-galactosamine conjugated ASOs. CD22 is a cell surface receptor expressed exclusively on B cells thus presenting an attractive target for B cell specific delivery of drugs. Herein, we reported the synthesis of monovalent and trivalent ASO conjugates with biphenylcarbonyl (BPC) modified sialic acids and their study as ASO delivery agents into B cells. CD22 positive cells exhibited reduced potency when treated with ligand modified ASOs and mechanistic examination suggested reduced uptake into cells potentially as a result of sequestration of ASO by other cell-surface proteins.
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Affiliation(s)
- Gabrielle St-Pierre
- Department of Chemistry, Université de Montréal, PO Box 6128, Succ., Centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Sudip Pal
- Department of Chemistry, Université de Montréal, PO Box 6128, Succ., Centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Michael E Østergaard
- Medicinal Chemistry, Ionis Pharmaceuticals, Inc., 2855 Gazelle Court, Carlsbad, CA 92010, United States
| | - Tianyuan Zhou
- Medicinal Chemistry, Ionis Pharmaceuticals, Inc., 2855 Gazelle Court, Carlsbad, CA 92010, United States
| | - Jinghua Yu
- Medicinal Chemistry, Ionis Pharmaceuticals, Inc., 2855 Gazelle Court, Carlsbad, CA 92010, United States
| | - Michael Tanowitz
- Medicinal Chemistry, Ionis Pharmaceuticals, Inc., 2855 Gazelle Court, Carlsbad, CA 92010, United States
| | - Punit P Seth
- Medicinal Chemistry, Ionis Pharmaceuticals, Inc., 2855 Gazelle Court, Carlsbad, CA 92010, United States.
| | - Stephen Hanessian
- Department of Chemistry, Université de Montréal, PO Box 6128, Succ., Centre-ville, Montréal, Québec H3C 3J7, Canada.
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8
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Gasparrini F, Feest C, Bruckbauer A, Mattila PK, Müller J, Nitschke L, Bray D, Batista FD. Nanoscale organization and dynamics of the siglec CD22 cooperate with the cytoskeleton in restraining BCR signalling. EMBO J 2016; 35:258-80. [PMID: 26671981 PMCID: PMC4741297 DOI: 10.15252/embj.201593027] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 11/09/2022] Open
Abstract
Receptor organization and dynamics at the cell membrane are important factors of signal transduction regulation. Using super-resolution microscopy and single-particle tracking, we show how the negative coreceptor CD22 works with the cortical cytoskeleton in restraining BCR signalling. In naïve B cells, we found endogenous CD22 to be highly mobile and organized into nanodomains. The landscape of CD22 and its lateral diffusion were perturbed either in the absence of CD45 or when the CD22 lectin domain was mutated. To understand how a relatively low number of CD22 molecules can keep BCR signalling in check, we generated Brownian dynamic simulations and supported them with ex vivo experiments. This combined approach suggests that the inhibitory function of CD22 is influenced by its nanoscale organization and is ensured by its fast diffusion enabling a "global BCR surveillance" at the plasma membrane.
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Affiliation(s)
| | - Christoph Feest
- Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London, UK
| | - Andreas Bruckbauer
- Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London, UK
| | - Pieta K Mattila
- Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London, UK
| | - Jennifer Müller
- Chair of Genetics, Department of Biology, University of Erlangen, Erlangen, Germany
| | - Lars Nitschke
- Chair of Genetics, Department of Biology, University of Erlangen, Erlangen, Germany
| | - Dennis Bray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Facundo D Batista
- Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London, UK
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9
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Abstract
Why exactly some individuals develop autoimmune disorders remains unclear. The broadly accepted paradigm is that genetic susceptibility results in some break in immunological tolerance, may enhance the availability of autoantigens, and may enhance inflammatory responses. Some environmental insults that occur on this background of susceptibility may then contribute to autoimmunity. In this review we discuss some aspects related to inhibitory signaling and rare genetic variants, as well as additional factors that might contribute to autoimmunity including the possible role of clonal somatic mutations, the role of epigenetic events and the contribution of the intestinal microbiome. Genetic susceptibility alleles generally contribute to the loss of immunological tolerance, the increased availability of autoantigens, or an increase in inflammation. Apart from common genetic variants, rare loss-of-function genetic variants may also contribute to the pathogenesis of autoimmunity. Studies of an inhibitory signaling pathway in B cells helped identify a negative regulatory enzyme called sialic acid acetyl esterase. The study of rare genetic variants of this enzyme provides an illustrative example showing the importance of detailed functional analyses of variant alleles and the need to exclude functionally normal common or rare genetic variants from analysis. It has also become clear that pathways that are functionally impacted by either common or rare defective variants can also be more significantly compromised by gene expression changes that may result from epigenetic alterations. Another important and evolving area that has been discussed relates to the role of the intestinal microbiome in influencing helper T cell polarization and the development of autoimmunity.
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Affiliation(s)
- Shiv Pillai
- Massachusetts General Hospital, Center for Cancer Research, Harvard Medical School, Boston, MA 02129, USA.
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10
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Yuan J, Yu M, Cao AL, Chen X, Zhang LH, Song Y, Cheng X, Zhou ZH, Wang M, Guo HP, Du R, Liao YH. A novel epitope from CD22 regulates Th1 and Th17 cell function in systemic lupus erythematosus. PLoS One 2013; 8:e64572. [PMID: 23704998 PMCID: PMC3660346 DOI: 10.1371/journal.pone.0064572] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 04/17/2013] [Indexed: 12/22/2022] Open
Abstract
The published antibodies (Abs) against CD22 on B cells including Epratuzumab could inhibit B cell activation mainly through binding to C2-set Ig domain of CD22, but they are rarely reported to modulate the pathogenic CD4+ T cell function in systemic lupus erythematosus (SLE). Recently, it was proved that the extracellular amino-terminal V-set Ig domain of CD22 might mediate the interaction of B and T cells, but for now the exact effect of this domain on CD4+ T cell biology have not been identified. Thus, in this study, we screened out a peptide termed B2285 from this V-set Ig domain, developed the novel specific anti-B2285 Abs in rabbits, and investigated their effects in MRL/lpr mice with spontaneous SLE. The results showed that anti-B2285 Abs could ameliorate the disease severity obviously in spontaneous SLE mice with the decreased differentiations of Th1 and Th17 cells and no changes of Th2 and Treg cells. In co-cultured B cells and CD4+ T cells, this specific anti-CD22 Abs was observed to inhibit the anti-dsDNA Abs production, CD4+ T cells proliferation, the protein levels of T-bet and RORγt, and the mRNA levels of TNF-α, IFN-γ, IL-6 and IL-17 in CD4+ T cells. Moreover, the expression of CD45RO on CD4+ T cells could be also apparently diminished by this novel Abs. The data suggested that anti-B2285 Abs could slow SLE progression significantly by regulating Th1 and Th17 cells function via B-T cell interaction and the cytokine network regulation. The treatment against V-set Ig domain of CD22 would be a valuable therapeutic method for SLE and other autoimmune diseases.
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Affiliation(s)
- Jing Yuan
- Laboratory of Cardiovascular Immunology, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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11
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Abstract
West Nile virus (WNV) is a RNA virus of the family Flaviviridae and the leading cause of mosquito-borne encephalitis in the United States. Humoral immunity is essential for protection against WNV infection; however, the requirements for initiating effective antibody responses against WNV infection are still unclear. CD22 (Siglec-2) is expressed on B cells and regulates B cell receptor signaling, cell survival, proliferation, and antibody production. In this study, we investigated how CD22 contributes to protection against WNV infection and found that CD22 knockout (Cd22(-/-)) mice were highly susceptible to WNV infection and had increased viral loads in the serum and central nervous system (CNS) compared to wild-type (WT) mice. This was not due to a defect in humoral immunity, as Cd22(-/-) mice had normal WNV-specific antibody responses. However, Cd22(-/-) mice had decreased WNV-specific CD8(+) T cell responses compared to those of WT mice. These defects were not simply due to reduced cytotoxic activity or increased cell death but, rather, were associated with decreased lymphocyte migration into the draining lymph nodes (dLNs) of infected Cd22(-/-) mice. Cd22(-/-) mice had reduced production of the chemokine CCL3 in the dLNs after infection, suggesting that CD22 affects chemotaxis via controlling chemokine production. CD22 was not restricted to B cells but was also expressed on a subset of splenic DCIR2(+) dendritic cells that rapidly expand early after WNV infection. Thus, CD22 plays an essential role in controlling WNV infection by governing cell migration and CD8(+) T cell responses.
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12
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IVIg modulates BCR signaling through CD22 and promotes apoptosis in mature human B lymphocytes. Blood 2010; 116:1698-704. [DOI: 10.1182/blood-2009-12-261461] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Among various mechanisms for interactions with B cells, intravenous immunoglobulin (IVIg) may operate through the insertion of its Fc part into the Fc-γ receptor, or the binding of its sialic acid (SA)–bearing glycans to the negatively regulating CD22 lectin. It appeared that IVIg reduces B lymphocyte viability in a dose- and time-dependent manner. Furthermore, we show by confocal microscopy that SA-positive IgG, but not SA-negative IgG bind to CD22. This interaction reduces the strength of B-cell receptor–mediated signaling trough down-regulating tyrosine phosphorylation of Lyn and the B-cell linker proteins, and up-regulating phospholipase Cγ2 activation. This cascade resulted in a sustained activation of Erk 1/2 and arrest of the cell cycle at the G1 phase. These changes may be accounted for the efficacy of IVIg in autoimmune diseases.
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Townsend MJ, Monroe JG, Chan AC. B-cell targeted therapies in human autoimmune diseases: an updated perspective. Immunol Rev 2010; 237:264-83. [DOI: 10.1111/j.1600-065x.2010.00945.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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14
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Odaka M, Hasegawa M, Hamaguchi Y, Ishiura N, Kumada S, Matsushita T, Komura K, Sato S, Takehara K, Fujimoto M. Autoantibody-mediated regulation of B cell responses by functional anti-CD22 autoantibodies in patients with systemic sclerosis. Clin Exp Immunol 2010; 159:176-84. [PMID: 19919568 PMCID: PMC2810386 DOI: 10.1111/j.1365-2249.2009.04059.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2009] [Indexed: 01/13/2023] Open
Abstract
Studies have demonstrated that B cells play important roles in systemic sclerosis (SSc), especially through the CD19/CD22 autoimmune loop. CD22 is a B cell-specific inhibitory receptor that dampens B cell antigen receptor (BCR) signalling via tyrosine phosphorylation-dependent mechanism. In this study, we examined the presence and functional property of circulating autoantibodies reacting with CD22 in systemic sclerosis. Serum samples from 10 tight skin (TSK/+) mice and 50 SSc patients were assessed for anti-CD22 autoantibodies by enzyme-linked immunosorbent assays using recombinant mouse or human CD22. The association between anti-CD22 antibodies and clinical features was also investigated in SSc patients. Furthermore, the influence of SSc serum including anti-CD22 autoantibodies for CD22 tyrosine phosphorylation was examined by Western blotting using phosphotyrosine-specific antibodies reacting with four major tyrosine motifs of CD22 cytoplasmic domain. Anti-CD22 autoantibodies were positive in 80% of TSK/+ mice and in 22% of SSc patients. Patients positive for anti-CD22 antibodies showed significantly higher modified Rodnan skin thickness score compared with patients negative for anti-CD22 antibodies. Furthermore, anti-CD22 antibodies from patients' sera were capable of reducing phosphorylation of all four CD22 tyrosine motifs, while sera negative for anti-CD22 antibodies did not affect CD22 phosphorylation. Thus, a subset of SSc patients possessed autoantibodies reacting with a major inhibitory B cell response regulator, CD22. Because these antibodies can interfere CD22-mediated suppression onto B cell activation in vitro, SSc B cells produce functional autoantibodies that can enhance their own activation. This unique regulation may contribute to the autoimmune aspect of SSc.
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Affiliation(s)
- M Odaka
- Department of Dermatology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
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15
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Ostrakhovitch EA, Wang Y, Li SSC. SAP binds to CD22 and regulates B cell inhibitory signaling and calcium flux. Cell Signal 2008; 21:540-50. [PMID: 19150402 DOI: 10.1016/j.cellsig.2008.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 12/10/2008] [Accepted: 12/15/2008] [Indexed: 01/25/2023]
Abstract
The signaling lymphocyte activation molecule (SLAM)-associated protein (SAP or SH2D1A) is an important regulator of immune function which, when mutated or deleted, causes the X-linked lymphoproliferative syndrome (XLP). Because B cell lymphoma is a major phenotype of XLP, it is important to understand the function of SAP in B cells. Here we report that SAP is expressed endogenously in mouse splenic B cells, is inducibly expressed in the human BJAB cells, and co-localizes and interacts with CD22. We also show that SAP binding to the inhibitory immunoreceptor CD22 regulates calcium mobilization in B cells. Moreover, forced expression of SAP leads to constitutive CD22 tyrosine phosphorylation and decreased Ca(2+) response in B cells. Biochemical analysis reveals that, in response to IgM cross-linking, the phosphorylation of Syk, Blnk, or PLCgamma2 and their interactions with one another were either diminished or completely abolished in SAP-expressing cells compared to cells that lack SAP. Collectively our work identifies a novel role for SAP in B cells and extends its function to inhibitory immunoreceptor signaling and calcium mobilization.
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Affiliation(s)
- Elena A Ostrakhovitch
- Department of Biochemistry and the Siebens-Drake Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada N6A 5C1.
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16
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Abstract
The appropriate activation of B cells is critical for the development and operation of immune responses and is dependent on the extensive coordination of intra- and intercellular communications in response to antigen stimulation. An accurate description of the B cell-activation process requires investigation of these interactions within their correct cellular context both at high resolution and in real time. Here, we discuss a number of recent studies that have offered insight into the early molecular events of B cell activation. We suggest that segregation within the B cell membrane triggers localized cytoskeleton reorganisation and signaling, allowing the formation of B cell receptor (BCR) microclusters. These BCR microclusters are the sites for the coordinated recruitment of the signalosome and are propagated during B cell spreading. We discuss the recent identification of a critical role for CD19 in the B cell response to membrane-bound antigen and suggest a mechanism involving BCR microclusters by which it mediates its stimulatory function. Finally, we consider research that has taken advantage of recent technological advances in multiphoton microscopy that have allowed its application to the investigation of the dynamics of membrane-bound antigen presentation and subsequent B cell activation in lymph nodes in vivo.
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Affiliation(s)
- Naomi E Harwood
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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17
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Batista FD, Arana E, Barral P, Carrasco YR, Depoil D, Eckl-Dorna J, Fleire S, Howe K, Vehlow A, Weber M, Treanor B. The role of integrins and coreceptors in refining thresholds for B-cell responses. Immunol Rev 2007; 218:197-213. [PMID: 17624954 DOI: 10.1111/j.1600-065x.2007.00540.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Despite compelling evidence that a large proportion of antigens encountered in vivo by B cells are membrane bound, the general view is that B cells are mainly activated by soluble antigens. This notion may have been biased somewhat over the years because the high affinity of the B-cell receptor (BCR) for soluble intact ligands allows efficient B-cell stimulation in vitro. In vivo, however, even soluble antigens are likely to be deposited on the surface of antigen-presenting cells, either by complement or Fc receptors in the form of immune complexes, thus becoming more potent stimulators of B-cell activation. In this framework, the BCR works in a complex environment of integrins and coreceptors, as well as the B-cell cytoskeleton. Over the last few years, we have focused on B-cell membrane-bound antigen recognition. Here, we discuss some of our findings in the context of what is currently known in this exciting new field.
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Affiliation(s)
- Facundo D Batista
- Lymphocyte Interaction Laboratory, London Research Institute, Cancer Research UK, London, UK.
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18
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Horikawa K, Martin SW, Pogue SL, Silver K, Peng K, Takatsu K, Goodnow CC. Enhancement and suppression of signaling by the conserved tail of IgG memory-type B cell antigen receptors. ACTA ACUST UNITED AC 2007; 204:759-69. [PMID: 17420266 PMCID: PMC2118534 DOI: 10.1084/jem.20061923] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Immunological memory is characterized by heightened immunoglobulin (Ig) G antibody production caused in part by enhanced plasma cell formation conferred by conserved transmembrane and cytoplasmic segments in isotype-switched IgG B cell receptors. We tested the hypothesis that the IgG tail enhances intracellular B cell antigen receptor (BCR) signaling responses to antigen by analyzing B cells from Ig transgenic mice with IgM receptors or chimeric IgMG receptors containing the IgG tail segment. The IgG tail segment enhanced intracellular calcium responses but not tyrosine or extracellular signal–related kinase (ERK) phosphorylation. Biochemical analysis and crosses to CD22-deficient mice established that IgG tail enhancement of calcium and antibody responses, as well as marginal zone B cell formation, was not due to diminished CD22 phosphorylation or inhibitory function. Microarray profiling showed no evidence for enhanced signaling by the IgG tail for calcium/calcineurin, ERK, or nuclear factor κB response genes and little evidence for any enhanced gene induction. Instead, almost half of the antigen-induced gene response in IgM B cells was diminished 50–90% by the IgG tail segment. These findings suggest a novel “less-is-more” hypothesis to explain how switching to IgG enhances B cell memory responses, whereby decreased BCR signaling to genes that oppose marginal zone and plasma cell differentiation enhances the formation of these key cell types.
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MESH Headings
- Animals
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- Calcium/metabolism
- Cell Differentiation
- Conserved Sequence
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Gene Expression Profiling
- Gene Expression Regulation
- Immunoglobulin M/immunology
- Immunologic Memory/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphotyrosine/metabolism
- Receptors, Antigen, B-Cell/chemistry
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/immunology
- Receptors, Antigen, B-Cell/metabolism
- Receptors, IgG/chemistry
- Receptors, IgG/genetics
- Receptors, IgG/immunology
- Receptors, IgG/metabolism
- Sialic Acid Binding Ig-like Lectin 2/genetics
- Sialic Acid Binding Ig-like Lectin 2/metabolism
- Signal Transduction/immunology
- Transcriptional Activation
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Affiliation(s)
- Keisuke Horikawa
- Immunogenomics Laboratory, The Australian Phenomics Facility, The John Curtin School of Medical Research, The Australian National University, Canberra 0200, Australia
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19
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Naito Y, Takematsu H, Koyama S, Miyake S, Yamamoto H, Fujinawa R, Sugai M, Okuno Y, Tsujimoto G, Yamaji T, Hashimoto Y, Itohara S, Kawasaki T, Suzuki A, Kozutsumi Y. Germinal center marker GL7 probes activation-dependent repression of N-glycolylneuraminic acid, a sialic acid species involved in the negative modulation of B-cell activation. Mol Cell Biol 2007; 27:3008-22. [PMID: 17296732 PMCID: PMC1899932 DOI: 10.1128/mcb.02047-06] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sialic acid (Sia) is a family of acidic nine-carbon sugars that occupies the nonreducing terminus of glycan chains. Diversity of Sia is achieved by variation in the linkage to the underlying sugar and modification of the Sia molecule. Here we identified Sia-dependent epitope specificity for GL7, a rat monoclonal antibody, to probe germinal centers upon T cell-dependent immunity. GL7 recognizes sialylated glycan(s), the alpha2,6-linked N-acetylneuraminic acid (Neu5Ac) on a lactosamine glycan chain(s), in both Sia modification- and Sia linkage-dependent manners. In mouse germinal center B cells, the expression of the GL7 epitope was upregulated due to the in situ repression of CMP-Neu5Ac hydroxylase (Cmah), the enzyme responsible for Sia modification of Neu5Ac to Neu5Gc. Such Cmah repression caused activation-dependent dynamic reduction of CD22 ligand expression without losing alpha2,6-linked sialylation in germinal centers. The in vivo function of Cmah was analyzed using gene-disrupted mice. Phenotypic analyses showed that Neu5Gc glycan functions as a negative regulator for B-cell activation in assays of T-cell-independent immunization response and splenic B-cell proliferation. Thus, Neu5Gc is required for optimal negative regulation, and the reaction is specifically suppressed in activated B cells, i.e., germinal center B cells.
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Affiliation(s)
- Yuko Naito
- Laboratory of Membrane Biochemistry and Biophysics, Graduate School of Biostudies, Kyoto University, Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan
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20
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Haas KM, Sen S, Sanford IG, Miller AS, Poe JC, Tedder TF. CD22 ligand binding regulates normal and malignant B lymphocyte survival in vivo. THE JOURNAL OF IMMUNOLOGY 2006; 177:3063-73. [PMID: 16920943 DOI: 10.4049/jimmunol.177.5.3063] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The CD22 extracellular domain regulates B lymphocyte function by interacting with alpha2,6-linked sialic acid-bearing ligands. To understand how CD22 ligand interactions affect B cell function in vivo, mouse anti-mouse CD22 mAbs were generated that inhibit CD22 ligand binding to varying degrees. Remarkably, mAbs which blocked CD22 ligand binding accelerated mature B cell turnover by 2- to 4-fold in blood, spleen, and lymph nodes. CD22 ligand-blocking mAbs also inhibited the survival of adoptively transferred normal (73-88%) and malignant (90%) B cells in vivo. Moreover, mAbs that bound CD22 ligand binding domains induced significant CD22 internalization, depleted marginal zone B cells (82-99%), and reduced mature recirculating B cell numbers by 75-85%. The CD22 mAb effects were independent of complement and FcRs, and the CD22 mAbs had minimal effects in CD22AA mice that express mutated CD22 that is not capable of ligand binding. These data demonstrate that inhibition of CD22 ligand binding can disrupt normal and malignant B cell survival in vivo and suggest a novel mechanism of action for therapeutics targeting CD22 ligand binding domains.
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Affiliation(s)
- Karen M Haas
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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21
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Ferry H, Crockford TL, Cockford TL, Silver K, Rust N, Goodnow CC, Cornall RJ. Analysis of Lyn/CD22 double-deficient B cells in vivo demonstrates Lyn- and CD22-independent pathways affecting BCR regulation and B cell survival. Eur J Immunol 2006; 35:3655-63. [PMID: 16278813 DOI: 10.1002/eji.200535247] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
B cell fate is determined by the strength of signals from the antigen receptor and from co-receptors that adjust the activation threshold and tune the B cell to its environment. These co-receptors have been broadly classified into inhibitory and enhancing groups, yet some, such as CD22, may have dual effects. CD22 recruits a variety of signal enhancers at the same time as Lyn-dependent phosphorylation leads to the binding of the inhibitory phosphatase SHP-1. To assess the relative importance of Lyn- and CD22-dependent and -independent pathways, we generated Lyn and CD22 single-deficient mice and Lyn/CD22 double-deficient mice expressing the MD4 immunoglobulin transgene against hen egg lysozyme (IgHEL). This genetic approach has enabled us to compare the contributions of Lyn and CD22 to B cell development in vivo, independent of BCR specificity and in the presence and absence of self-antigen. Our results show that although the effects of Lyn are dominant in negative regulation of B cell hyperactivity, Lyn and CD22 have independent and additive effects on B cell survival. These findings emphasize the subtle nature of regulation at the BCR and the usefulness of genetic complementation to dissect common and parallel pathways.
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MESH Headings
- Animals
- B-Lymphocytes/cytology
- B-Lymphocytes/enzymology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Survival/genetics
- Cell Survival/immunology
- Cells, Cultured
- Immune Tolerance/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Receptors, Antigen, B-Cell/antagonists & inhibitors
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Antigen, B-Cell/physiology
- Sialic Acid Binding Ig-like Lectin 2/genetics
- Sialic Acid Binding Ig-like Lectin 2/physiology
- src-Family Kinases/deficiency
- src-Family Kinases/genetics
- src-Family Kinases/physiology
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Affiliation(s)
- Helen Ferry
- Henry Wellcome Building of Molecular Physiology, Oxford, UK
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22
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Gazumyan A, Reichlin A, Nussenzweig MC. Ig beta tyrosine residues contribute to the control of B cell receptor signaling by regulating receptor internalization. J Exp Med 2006; 203:1785-94. [PMID: 16818674 PMCID: PMC2118343 DOI: 10.1084/jem.20060221] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Accepted: 06/02/2006] [Indexed: 12/14/2022] Open
Abstract
Immunoglobulin (Ig)alpha and Igbeta initiate B cell receptor (BCR) signaling through immune receptor tyrosine activation motifs (ITAMs) that are targets of SH2 domain-containing kinases. To examine the function of Igbeta ITAM tyrosine resides in mature B cells in vivo, we exchanged these residues for alanine by gene targeting (Igbeta(AA)). Mutant mice showed normal development of all B cell subtypes with the exception of B1 cells that were reduced by fivefold. However, primary B cells purified from Igbeta(AA) mice showed significantly decreased steady-state and ligand-mediated BCR internalization and higher levels of cell surface IgM and IgD. BCR cross-linking resulted in decreased Src and Syk activation but paradoxically enhanced and prolonged BCR signaling, as measured by cellular tyrosine phosphorylation, Ca(++) flux, AKT, and ERK activation. In addition, B cells with the ITAM mutant receptor showed an enhanced response to a T-independent antigen. Thus, Igbeta ITAM tyrosines help set BCR signaling threshold by regulating receptor internalization.
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Affiliation(s)
- Anna Gazumyan
- Laboratory of Molecular Immunology and 2Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA.
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23
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Fujimoto M, Kuwano Y, Watanabe R, Asashima N, Nakashima H, Yoshitake S, Okochi H, Tamaki K, Poe JC, Tedder TF, Sato S. B cell antigen receptor and CD40 differentially regulate CD22 tyrosine phosphorylation. THE JOURNAL OF IMMUNOLOGY 2006; 176:873-9. [PMID: 16393971 DOI: 10.4049/jimmunol.176.2.873] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cell surface molecules on lymphocytes positively or negatively modulate the Ag receptor signaling, and thus regulate the fate of the cell. CD22 is a B cell-specific cell surface protein that contains multiple ITIMs in the cytoplasmic tail, and critically regulates B cell activation and survival. CD22 regulation on B cell signaling is complex because CD22 can have both positive and negative roles in various contexts. We generated phosphospecific polyclonal Abs reacting four major CD22 tyrosine motifs (Y762, Y807, Y822, and Y842) and analyzed the pattern and intensity of phosphorylation of these tyrosine residues. The tyrosine motifs, Y762, Y822, and Y842, are considered as ITIM, whereas the other, Y807, is suggested to be important for Grb2 recruitment. Approximately 10% of the four tyrosine residues were constitutively phosphorylated. Upon anti-IgM ligation, CD22 Y762 underwent most rapid phosphorylation, whereas all four tyrosine residues were eventually phosphorylated equally at approximately 35% of all CD22 molecules in the cell. By contrast, anti-CD40 stimulation specifically up-regulated anti-IgM-induced phosphorylation of tyrosines within two ITIM motifs, Y762 and Y842, which was consistent with in vivo finding of the negative role of CD22 in CD40 signaling. Thus, CD22 phosphorylation is not only quantitatively but also qualitatively regulated by different stimulations, which may determine the outcome of B cell signaling.
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Affiliation(s)
- Manabu Fujimoto
- Department of Dermatology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
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24
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Mizuno K, Tagawa Y, Watanabe N, Ogimoto M, Yakura H. SLP-76 is recruited to CD22 and dephosphorylated by SHP-1, thereby regulating B cell receptor-induced c-Jun N-terminal kinase activation. Eur J Immunol 2005; 35:644-54. [PMID: 15668918 DOI: 10.1002/eji.200425465] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Despite the important role in the development and activation of T cells, NK cells, mast cells, and macrophages, the expression and function of SLP-76 in B cells have been largely unknown. Here we demonstrate that SLP-76 is expressed in all mouse B cell lines tested and in normal splenic B cells, and serves as an SHP-1 substrate. Dephosphorylation of SLP-76 by SHP-1 inhibits its association with Nck, down-regulating c-Jun N-terminal kinase (JNK) activation and exerting a positive effect on apoptosis. Knockdown of SLP-76 in WEHI-231 cells by small interfering RNA attenuated JNK activation, but showed little effects on extracellular signal-regulated kinase (ERK) or p38 activation. Although WEHI-231 does not express linker for activation of T cells (LAT), SLP-76 localizes in membrane fraction, which increases following B cell receptor (BCR) cross-linking. Further analyses revealed that SLP-76 complexed with Gads is associated with tyrosine-phosphorylated CD22 through the SH2 domains of SLP-76 and Gads. Given that SHP-1 binds to CD22 upon BCR ligation, our findings suggest that dephosphorylation of SLP-76 recruited to CD22 by SHP-1 inhibits BCR-induced JNK activation, dictating apoptosis.
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Affiliation(s)
- Kazuya Mizuno
- Department of Immunology and Signal Transduction, Tokyo Metropolitan Institute for Neuroscience, Tokyo Metropolitan Organization for Medical Research, Tokyo, Japan.
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25
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Tedder TF, Poe JC, Haas KM. CD22: A Multifunctional Receptor That Regulates B Lymphocyte Survival and Signal Transduction. Adv Immunol 2005; 88:1-50. [PMID: 16227086 DOI: 10.1016/s0065-2776(05)88001-0] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent advances in the study of CD22 indicate a complex role for this transmembrane glycoprotein member of the immunoglobulin superfamily in the regulation of B lymphocyte survival and proliferation. CD22 has been previously recognized as a potential lectin-like adhesion molecule that binds alpha2,6-linked sialic acid-bearing ligands and as an important regulator of B-cell antigen receptor (BCR) signaling. However, genetic studies in mice reveal that some CD22 functions are regulated by ligand binding, whereas other functions are ligand-independent and may only require expression of an intact CD22 cytoplasmic domain at the B-cell surface. Until recently, most of the functional activity of CD22 has been widely attributed to CD22's ability to recruit potent intracellular phosphatases and limit the intensity of BCR-generated signals. However, a more complex role for CD22 has recently emerged, including a central role in a novel regulatory loop controlling the CD19/CD21-Src-family protein tyrosine kinase (PTK) amplification pathway that regulates basal signaling thresholds and intensifies Src-family kinase activation after BCR ligation. CD22 is also central to the regulation of peripheral B-cell homeostasis and survival, the promotion of BCR-induced cell cycle progression, and is a potent regulator of CD40 signaling. Herein we discuss our current understanding of how CD22 governs these complex and overlapping processes, how alterations in these tightly controlled regulatory activities may influence autoimmune disease, and the current and future applications of CD22-directed therapies in oncology and autoimmunity.
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Affiliation(s)
- Thomas F Tedder
- Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA
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26
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St Clair EW, Tedder TF. New prospects for autoimmune disease therapy: B cells on deathwatch. ACTA ACUST UNITED AC 2005; 54:1-9. [PMID: 16385491 DOI: 10.1002/art.21525] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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27
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Kitazume S, Saido TC, Hashimoto Y. Alzheimer's beta-secretase cleaves a glycosyltransferase as a physiological substrate. Glycoconj J 2004; 20:59-62. [PMID: 14973371 DOI: 10.1023/b:glyc.0000016743.25495.45] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Alzheimer's beta-secretase (BACE1) is a membrane-bound protease that cleaves the amyloid precursor protein (APP) in the trans-Golgi network, an initial step in the pathogenesis of Alzheimer's disease. Although BACE1 is distributed among various tissues including brain, its physiological substrate other than APP have not been identified. We have recently found that when BACE1 was overexpressed in COS cells together with alpha2,6-sialyltransferase (ST6Gal I), the secretion of ST6Gal I markedly increased, suggesting that BACE1 cleaves ST6Gal I as a physiological substrate. Thus BACE1 is the first identified protease that is responsible for the cleavage and secretion of glycosyltransferases.
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Affiliation(s)
- Shinobu Kitazume
- Glyco-chain Functions Laboratory, Frontier Research System and Laboratory for Proteolytic Neuroscience, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
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28
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Poe JC, Fujimoto Y, Hasegawa M, Haas KM, Miller AS, Sanford IG, Bock CB, Fujimoto M, Tedder TF. CD22 regulates B lymphocyte function in vivo through both ligand-dependent and ligand-independent mechanisms. Nat Immunol 2004; 5:1078-87. [PMID: 15378059 DOI: 10.1038/ni1121] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 08/25/2004] [Indexed: 12/12/2022]
Abstract
The interaction of CD22 with alpha2,6-linked sialic acid ligands has been widely proposed to regulate B lymphocyte function and migration. Here, we generated gene-targeted mice that express mutant CD22 molecules that do not interact with these ligands. CD22 ligand binding regulated the expression of cell surface CD22, immunoglobulin M and major histocompatibility complex class II on mature B cells, maintenance of the marginal zone B cell population, optimal B cell antigen receptor-induced proliferation, and B cell turnover rates. However, CD22 negative regulation of calcium mobilization after B cell antigen receptor ligation, CD22 phosphorylation, recruitment of SHP-1 to CD22 and B cell migration did not require CD22 ligand engagement. These observations resolve longstanding questions regarding the physiological importance of CD22 ligand binding in the regulation of B cell function in vivo.
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Affiliation(s)
- Jonathan C Poe
- Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA
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29
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Poe JC, Haas KM, Uchida J, Lee Y, Fujimoto M, Tedder TF. Severely impaired B lymphocyte proliferation, survival, and induction of the c-Myc:Cullin 1 ubiquitin ligase pathway resulting from CD22 deficiency on the C57BL/6 genetic background. THE JOURNAL OF IMMUNOLOGY 2004; 172:2100-10. [PMID: 14764675 DOI: 10.4049/jimmunol.172.4.2100] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Understanding the molecular mechanisms through which CD22 regulates B lymphocyte homeostasis, signal transduction, and tolerance is critical to defining normal B cell function and understanding the role of CD22 in autoimmunity. Therefore, CD22 function was examined in vivo and in vitro using B cells from CD22-deficient (CD22(-/-)) mice. Backcrossing of founder CD22(-/-) mice onto the C57BL/6 (B6) genetic background from a B6/129 mixed background resulted in a dramatically reduced B cell proliferative response following IgM ligation, characterized by a paucity of lymphoblasts and augmented apoptosis. Also, the phenotype of splenic B6 CD22(-/-) B cells was uniquely HSA(high) and IgD(low)/CD21(low) with intermediate levels of CD5 expression, although the percentages of mature and transitional B cells were normal. That B6 CD22(-/-) B cells predominantly underwent apoptosis following IgM ligation correlated with this unique tolerant phenotype, as well as defective induction of the c-Myc:Cullin 1 (CUL1) ubiquitin ligase pathway that is necessary for progression to the S phase of cell cycle. CD40 ligation compensated for CD22 deficiency by restoring lymphoblast development, proliferation, c-Myc and CUL1 expression, and protein ubiquitination/degradation in IgM-stimulated B6 CD22(-/-) B cell cultures. Thereby, this study expands our current understanding of the complex role of CD22 during B cell homeostasis and Ag responsiveness, and reveals that the impact of CD22 deficiency is dictated by the genetic background on which it is rendered. Moreover, this study defines CD22 and CD40 as the first examples of lymphocyte coreceptors that influence induction of the c-Myc:CUL1 ubiquitin ligase pathway.
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MESH Headings
- Adjuvants, Immunologic/physiology
- Animals
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- Apoptosis/genetics
- Apoptosis/immunology
- B-Lymphocyte Subsets/enzymology
- B-Lymphocyte Subsets/immunology
- B-Lymphocyte Subsets/metabolism
- B-Lymphocyte Subsets/pathology
- Cell Adhesion Molecules
- Cell Cycle Proteins/biosynthesis
- Cell Cycle Proteins/metabolism
- Cell Cycle Proteins/physiology
- Cell Division/genetics
- Cell Division/immunology
- Cell Membrane/genetics
- Cell Membrane/immunology
- Cell Survival/genetics
- Cell Survival/immunology
- Cells, Cultured
- Cullin Proteins/biosynthesis
- Cullin Proteins/metabolism
- Cullin Proteins/physiology
- Enzyme Activation/genetics
- Enzyme Activation/immunology
- Enzyme Induction/genetics
- Enzyme Induction/immunology
- Growth Inhibitors/physiology
- Immunoglobulin M/physiology
- Immunophenotyping
- Lectins/deficiency
- Lectins/genetics
- Lectins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphatidylinositol 3-Kinases/metabolism
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- Proto-Oncogene Proteins c-myc/biosynthesis
- Proto-Oncogene Proteins c-myc/deficiency
- Proto-Oncogene Proteins c-myc/physiology
- Sialic Acid Binding Ig-like Lectin 2
- Signal Transduction/genetics
- Signal Transduction/immunology
- Ubiquitin-Protein Ligases/biosynthesis
- Ubiquitin-Protein Ligases/deficiency
- Ubiquitin-Protein Ligases/physiology
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Affiliation(s)
- Jonathan C Poe
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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30
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Chen J, McLean PA, Neel BG, Okunade G, Shull GE, Wortis HH. CD22 attenuates calcium signaling by potentiating plasma membrane calcium-ATPase activity. Nat Immunol 2004; 5:651-7. [PMID: 15133509 DOI: 10.1038/ni1072] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Accepted: 03/16/2004] [Indexed: 01/17/2023]
Abstract
Binding of antigen to the B cell receptor induces a calcium response, which is required for proliferation and antibody production. CD22, a B cell surface protein, inhibits this signal through mechanisms that have been obscure. We report here that CD22 augments calcium efflux after B cell receptor crosslinking. Inhibition of plasma membrane calcium-ATPase (PMCA) attenuated these effects, as did disruption by homologous recombination of the gene encoding PMCA4a and PMCA4b. PMCA coimmunoprecipitated with CD22 in an activation-dependent way. CD22 cytoplasmic tyrosine residues were required for association with PMCA and enhancement of calcium efflux. Moreover, CD22 regulation of efflux and the calcium response required the tyrosine phosphatase SHP-1. Thus, SHP-1 and PMCA provide a mechanism by which CD22, a tissue-specific negative regulator, can affect calcium responses.
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Affiliation(s)
- Jie Chen
- Department of Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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31
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Hokazono Y, Adachi T, Wabl M, Tada N, Amagasa T, Tsubata T. Inhibitory coreceptors activated by antigens but not by anti-Ig heavy chain antibodies install requirement of costimulation through CD40 for survival and proliferation of B cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:1835-43. [PMID: 12902484 DOI: 10.4049/jimmunol.171.4.1835] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ag-induced B cell proliferation in vivo requires a costimulatory signal through CD40, whereas B cell Ag receptor (BCR) ligation by anti-Ig H chain Abs, such as anti-Ig micro H chain Ab and anti-Ig delta H chain Ab, alone induces proliferation of B cells in vitro, even in the absence of CD40 ligation. In this study, we demonstrate that CD40 signaling is required for survival and proliferation of B cells stimulated by protein Ags in vitro as well as in vivo. This indicates that the in vitro system represents B cell activation in vivo, and that protein Ags generate BCR signaling distinct from that by anti-Ig H chain Abs. Indeed, BCR ligation by Ags, but not by anti-Ig H chain Abs, efficiently phosphorylates the inhibitory coreceptors CD22 and CD72. When these coreceptors are activated, anti-Ig H chain Ab-stimulated B cells can survive and proliferate only in the presence of CD40 signaling. Conversely, treatment of Ag-stimulated B cells with anti-CD72 mAb blocks CD72 phosphorylation and induces proliferation, even in the absence of CD40 signaling. These results strongly suggest that activation of B cells by anti-Ig H chain Abs involves their ability to silence the inhibitory coreceptors, and that the inhibitory coreceptors install requirement of CD40 signaling for survival and proliferation of Ag-stimulated B cells.
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MESH Headings
- Animals
- Antibodies, Anti-Idiotypic/pharmacology
- Antigens/pharmacology
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Antigens, Differentiation, B-Lymphocyte/physiology
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- CD40 Antigens/physiology
- Cell Adhesion Molecules
- Cell Cycle/immunology
- Cell Division/genetics
- Cell Division/immunology
- Cell Survival/genetics
- Cell Survival/immunology
- Cells, Cultured
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Heavy Chains/immunology
- Immunoglobulin lambda-Chains/genetics
- Immunoglobulin lambda-Chains/immunology
- Lectins/metabolism
- Lectins/physiology
- Lymphocyte Activation/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Nitrophenols/pharmacology
- Phenylacetates
- Phosphorylation
- Receptors, Antigen, B-Cell/immunology
- Receptors, Antigen, B-Cell/metabolism
- Sialic Acid Binding Ig-like Lectin 2
- Signal Transduction/genetics
- Signal Transduction/immunology
- Spleen/cytology
- Spleen/immunology
- Spleen/metabolism
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Affiliation(s)
- Yasuhisa Hokazono
- Laboratory of Immunology, School of Biomedical Science, Department of Immunology, Medical Research Institute, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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32
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Baba T, Fusaki N, Shinya N, Iwamatsu A, Hozumi N. Myosin is an in vivo substrate of the protein tyrosine phosphatase (SHP-1) after mIgM cross-linking. Biochem Biophys Res Commun 2003; 304:67-72. [PMID: 12705885 DOI: 10.1016/s0006-291x(03)00542-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
SHP-1 plays an important role in negative signaling in many cell types. For example, after BCR stimulation in apoptotic B cells, SHP-1 has been shown to be recruited to phosphorylated ITIMs present in receptors such as CD72. However, the SHP-1 substrates in the chicken B cell line, DT40, have been poorly undefined. To identify SHP-1 substrates in DT40, we used a trapping mutant SHP-1 C/S (a catalytically inactive form). BCR stimulation induced hyper-phosphorylation of 230 kDa protein in C/S transfectants. MALDI-TOF/MS analysis revealed that this was myosin carrying ITIM. SHP-1 was shown to bind to this ITIM in synthetic peptide binding experiment. Thus, myosin is a direct SHP-1 substrate in B cells. The results suggest that SHP-1 plays a critical role in the reorganization of cytoskeletal architecture mediated via BCR stimulation.
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Affiliation(s)
- Takeshi Baba
- Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda, 278-0022, Chiba, Japan
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33
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Baba T, Fusaki N, Shinya N, Iwamatsu A, Hozumi N. Actin tyrosine dephosphorylation by the Src homology 1-containing protein tyrosine phosphatase is essential for actin depolymerization after membrane IgM cross-linking. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:3762-8. [PMID: 12646642 DOI: 10.4049/jimmunol.170.7.3762] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Src homology protein 1 (SHP-1) plays an important role in B cell Ag receptor (BCR) differentiation, proliferation, survival, and apoptosis. After BCR stimulation in apoptotic cells, SHP-1 has been shown to be recruited to phosphorylated immunoreceptor tyrosine-based inhibitory motifs present in receptors such as CD22 and CD72. However, the substrates of SHP-1 in the chicken B cell line, DT40, have remained undefined. To identify SHP-1 substrates in DT40, we used a trapping mutant, SHP-1 C/S (a catalytically inactive form). Cross-linking of BCR induced hyperphosphorylation of approximately 44-kDa protein in C/S transfectants. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis revealed that this was actin (cytoplasmic type 5) carrying three immunoreceptor tyrosine-based inhibitory motif-like sequences. SHP-1 was shown to bind to one of these sequences in synthetic peptide binding experiment. Thus, actin is a direct SHP-1 substrate. Furthermore, more SHP-1 molecules translocate into lipid rafts, and their association with actin was increased after BCR stimulation. In C/S transfectants, actin polymerization induced by membrane IgM ligation was sustained to a greater extent for a longer time compared with wild-type transfectants. Therefore, actin dephosphorylation by SHP-1 is essential for actin depolymerization after BCR stimulation. Our data suggest that SHP-1 plays a pivotal role in reorganization of cytoskeletal architecture inducing actin dephosphorylation. These results clearly demonstrate the direct interaction of SHP-1 with actin.
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Affiliation(s)
- Takeshi Baba
- Research Institute for Biological Sciences, Tokyo University of Science, Chiba, Japan
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34
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Takashima S, Tsuji S, Tsujimoto M. Characterization of the second type of human beta-galactoside alpha 2,6-sialyltransferase (ST6Gal II), which sialylates Galbeta 1,4GlcNAc structures on oligosaccharides preferentially. Genomic analysis of human sialyltransferase genes. J Biol Chem 2002; 277:45719-28. [PMID: 12235148 DOI: 10.1074/jbc.m206808200] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel member of the human beta-galactoside alpha2,6-sialyltransferase (ST6Gal) family, designated ST6Gal II, was identified by BLAST analysis of expressed sequence tags and genomic sequences. The sequence of ST6Gal II encoded a protein of 529 amino acids, and it showed 48.9% amino acid sequence identity with human ST6Gal I. Recombinant ST6Gal II exhibited alpha2,6-sialyltransferase activity toward oligosaccharides that have the Galbeta1,4GlcNAc sequence at the nonreducing end of their carbohydrate groups, but it exhibited relatively low and no activities toward some glycoproteins and glycolipids, respectively. It is concluded that ST6Gal II is an oligosaccharide-specific enzyme compared with ST6Gal I, which exhibits broad substrate specificities, and is mainly involved in the synthesis of sialyloligosaccharides. The expression of the ST6Gal II gene was significantly detected by reverse transcription PCR in small intestine, colon, and fetal brain, whereas the ST6Gal I gene was ubiquitously expressed, and its expression levels were much higher than those of the ST6Gal II gene. The ST6Gal I gene was also expressed in all tumors examined, but no expression was observed for the ST6Gal II gene in these tumors. The ST6Gal II gene is located on chromosome 2 (2q11.2-q12.1), and it spans over 85 kb of human genomic DNA consisting of at least eight exons and shares a similar genomic structure with the ST6Gal I gene. In this paper, we have shown that ST6Gal I, which has been known as the sole member of the ST6Gal family, also has the counterpart enzyme (ST6Gal II) like other sialyltransferases.
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Affiliation(s)
- Shou Takashima
- Laboratory of Cellular Biochemistry, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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35
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Yang ZQ, Puffer EB, Pontrello JK, Kiessling LL. Synthesis of a multivalent display of a CD22-binding trisaccharide. Carbohydr Res 2002; 337:1605-13. [PMID: 12423961 DOI: 10.1016/s0008-6215(02)00270-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Multivalent interactions have been implicated in the binding of B-cell surface glycoprotein CD22 to its physiological ligands. Because CD22 can influence B-cell antigen receptor (BCR) signaling, multivalent ligands that cluster CD22 may influence B-cell responses. Here, we report an efficient synthesis of a fluorophore-labeled multivalent display of a CD22-binding trisaccharide, Neu5Acalpha2,6Galbeta1,4Glc, using the ring-opening metathesis polymerization (ROMP). Our synthetic strategy involves the modification of an N-hydroxysuccinimide (NHS) ester-substituted polymer generated by ROMP with the aminopropyl glycoside of the trisaccharide. The conjugation efficiency for the coupling is high; when 0.3 equiv of the trisaccharide derivative were used relative to NHS ester groups, the mole fraction (chi) of trisaccharide ligand incorporated onto the backbone was 0.3. A fluorescein-labeled version of the multivalent ligand binds to cells expressing CD22.
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Affiliation(s)
- Zhi-Qiang Yang
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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36
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Poe JC, Hasegawa M, Tedder TF. CD19, CD21, and CD22: multifaceted response regulators of B lymphocyte signal transduction. Int Rev Immunol 2002; 20:739-62. [PMID: 11913948 DOI: 10.3109/08830180109045588] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
B lymphocyte development and function depend upon the activity of intrinsic and B cell antigen receptor (BCR)-induced signals. These signals are interpreted, amplified, fine-tuned, or suppressed through the precise actions of specialized cell surface coreceptors, or "response regulators," that inform B cells of their extracellular environment. Important cell surface response regulators include the CD19/CD21 complex, CD22, and CD72. CD19 establishes a novel Src-family protein tyrosine kinase (PTK) amplification loop that regulates basal signaling thresholds and intensifies Src-family PTK activation following BCR ligation. In turn, CD22 limits the intensity of CD19-dependent, BCR-generated signals through the recruitment of potent phosphotyrosine and phosphoinositide phosphatases. Herein we discuss our current understanding of how CD19/CD21 and CD22 govern the emergence and intensity of BCR-mediated signals, and how alterations in these tightly controlled regulatory activities contribute to autoimmunity in mice and humans.
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MESH Headings
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, CD19/chemistry
- Antigens, CD19/genetics
- Antigens, CD19/metabolism
- Antigens, Differentiation, B-Lymphocyte/chemistry
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Autoimmunity
- B-Lymphocytes/immunology
- Cell Adhesion Molecules
- Humans
- Lectins
- Lymphocyte Activation
- Mice
- Mice, Knockout
- Models, Immunological
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Complement 3d/chemistry
- Receptors, Complement 3d/genetics
- Receptors, Complement 3d/metabolism
- Sialic Acid Binding Ig-like Lectin 2
- Signal Transduction
- src-Family Kinases/metabolism
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Affiliation(s)
- J C Poe
- Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA
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37
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Tsubata T. Molecular mechanisms for apoptosis induced by signaling through the B cell antigen receptor. Int Rev Immunol 2002; 20:791-803. [PMID: 11913950 DOI: 10.3109/08830180109045590] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Although the B cell antigen receptor (BCR) transmits survival and activation signals, BCR ligation can induce apoptosis in both immature and mature B cells. BCR-mediated apoptosis is suggested to play a role in self-tolerance by deleting self-reactive B cells. Generation of an apoptotic signal through BCR appears to depend on the composition of the higher order BCR complex and is suggested to occur outside the plasma membrane microdomains, termed lipid rafts. During BCR-mediated apoptosis, mitochondrial dysfunction is induced and is essential for apoptosis, probably by activating both caspases, cysteine proteases that play a central role in apoptosis, and caspase-independent effectors for apoptosis. Although signaling pathways for apoptosis are not yet fully defined in BCR-mediated apoptosis, expression of the proto-oncogene product c-Myc is enhanced upon BCR ligation, and c-Myc appears to mediate BCR ligation-induced apoptosis by causing mitochondrial dysfunction, suggesting that BCR-mediated apoptosis is a form of Myc-induced apoptosis.
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Affiliation(s)
- T Tsubata
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Japan.
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38
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Jin L, McLean PA, Neel BG, Wortis HH. Sialic acid binding domains of CD22 are required for negative regulation of B cell receptor signaling. J Exp Med 2002; 195:1199-205. [PMID: 11994425 PMCID: PMC2193702 DOI: 10.1084/jem.20011796] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2001] [Revised: 03/13/2002] [Indexed: 12/21/2022] Open
Abstract
CD22, a negative regulator of B cell antigen receptor signaling, binds glycoconjugates terminating in alpha2, 6 sialic acid. The physiological ligand(s) for CD22 remain unknown. We asked whether the sialic acid binding domains are necessary for CD22 to function as a negative regulator. We generated two mutants that lack sialic acid binding activity and expressed them in a novel CD22(-/-) murine B cell line. Anti-IgM activated B cells expressing either CD22 mutant had greater Ca(2+) responses than cells expressing wild-type CD22. Each variant also had reduced CD22 tyrosine phosphorylation and Src homology 2 domain-containing protein tyrosine phosphatase-1 association. These data suggest that the alpha2, 6 sialic acid ligand binding activity of CD22 is critical for its negative regulatory functions.
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Affiliation(s)
- Lei Jin
- Department of Pathology, Tufts University School of Medicine and Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA
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39
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Grobe K, Powell LD. Role of protein kinase C in the phosphorylation of CD33 (Siglec-3) and its effect on lectin activity. Blood 2002; 99:3188-96. [PMID: 11964282 DOI: 10.1182/blood.v99.9.3188] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD33 (Siglec-3) is a marker of myeloid progenitor cells, mature myeloid cells, and most myeloid leukemias. Although its biologic role remains unknown, it has been demonstrated to function as a sialic acid-specific lectin and a cell adhesion molecule. Many of the Siglecs (including CD33) have been reported to be tyrosine phosphorylated in the cytosolic tails under specific stimulation conditions. Here we report that CD33 is also a serine/threonine phosphoprotein, containing at least 2 sites of serine phosphorylation in its cytoplasmic domain, catalyzed by protein kinase C (PKC). Phosphorylation could be augmented by exposure to the protein kinase-activating cytokines interleukin 3, erythropoietin, or granulocyte-macrophage colony-stimulating factor, in a cytokine-dependent cell line, TF-1. The CD33 cytoplasmic tail was phosphorylated by PKC in vitro, in a Ca(++)/lipid-dependent manner. CHOK1 cells stably expressing CD33 with cytoplasmic tails of various length also showed phorbol myristate acetate (PMA)-dependent phosphorylation of CD33. Inhibition of CD33 phosphorylation with pharmacologic agents resulted in an increase of sialic acid-dependent rosette formation. Furthermore, the occupancy of the lectin site affected its basal level of phosphorylation. Rosette formation by COS cells expressing a form of CD33 lacking its cytoplasmic domain was not affected by these same agents. These data indicate that CD33 is a phosphoprotein, that its phosphorylation may be controlled by PKC downstream of cytokine stimulation, and that its phosphorylation is cross-regulated with its lectin activity. Notably, although this is the first example of serine/threonine phosphorylation in the subfamily of CD33-like Siglecs, some of the other members also have putative target sites in their cytoplasmic tails.
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Affiliation(s)
- Kay Grobe
- Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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40
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Moyron-Quiroz JE, Partida-Sánchez S, Donís-Hernández R, Sandoval-Montes C, Santos-Argumedo L. Expression and function of CD22, a B-cell restricted molecule. Scand J Immunol 2002; 55:343-51. [PMID: 11967115 DOI: 10.1046/j.1365-3083.2002.01063.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this work, we studied the expression and function of CD22 in murine B cells. CD22 has been previously characterized as an activation marker of mature B lymphocytes. However, we found that CD22 is expressed early during the ontogeny of B cells in the bone marrow and spleen, and was found on B cells isolated from all the different lymphoid compartments. We also found that B cells stimulated through the B-cell antigen receptor (BCR), CD38 and CD40, upregulated CD22 expression to maximal levels within 24 h after stimulation, but that the levels of CD22 declined at later times (48 and 72 h). CD22 is rapidly phosphorylated after BCR signal transduction, and is believed to downregulate B-cell activation. In this study, we did not detect CD22 phosphorylation in activated B cells after CD38 or CD40 cross-linking, even though CD22 was clearly phosphorylated in the BCR-stimulated B cells. Consistent with this, we found no evidence of physical association between CD38 or CD40 and CD22 in B cells. The lack of association or phosphorylation of CD22 induced by CD38 and CD40 cross-linking indicates that CD22 may not downregulate the activation induced by these two molecules.
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MESH Headings
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Animals
- Antigens, CD/analysis
- Antigens, CD/physiology
- Antigens, Differentiation/physiology
- Antigens, Differentiation, B-Lymphocyte/analysis
- Antigens, Differentiation, B-Lymphocyte/physiology
- B-Lymphocytes/chemistry
- B-Lymphocytes/physiology
- Bone Marrow/chemistry
- CD40 Antigens/physiology
- Cell Adhesion Molecules
- Lectins
- Membrane Glycoproteins
- Mice
- Mice, Inbred BALB C
- NAD+ Nucleosidase/physiology
- Phosphorylation
- Receptors, Antigen, B-Cell/physiology
- Sialic Acid Binding Ig-like Lectin 2
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Affiliation(s)
- J E Moyron-Quiroz
- Department of Cellular Biology, Centro de Investigación y Estudios Avanzados del I.P.N., 07360 México D.F., México
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41
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42
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Otipoby KL, Draves KE, Clark EA. CD22 regulates B cell receptor-mediated signals via two domains that independently recruit Grb2 and SHP-1. J Biol Chem 2001; 276:44315-22. [PMID: 11551923 DOI: 10.1074/jbc.m105446200] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recognition of antigen by the B cell antigen receptor (BCR) determines the subsequent fate of a B cell and is regulated in part by the involvement of other surface molecules, termed coreceptors. CD22 is a B cell-restricted coreceptor that gets rapidly tyrosyl-phosphorylated and recruits various signaling molecules to the membrane following BCR ligation. Although CD22 contains three immunoreceptor tyrosine-based inhibitory motifs (ITIMs), only the two carboxyl-terminal ITIM tyrosines are required for efficient recruitment of the SHP-1 phosphatase after BCR ligation. Furthermore, Grb2 is inducibly recruited to CD22 in human and murine B cells. Unlike SHP-1, Grb2 recruitment to CD22 is not inhibited by specific doses of the Src family kinase-specific inhibitor PP1. The tyrosine residue in CD22 required for Grb2 recruitment (Tyr-828) is distinct and independent from the two ITIM tyrosines required for efficient SHP-1 recruitment (Tyr-843 and Tyr-863). Individually both Lyn and Syk are required for maximal phosphorylation of CD22 following ligation of the BCR, and together Lyn and Syk are required for all of the constitutive and induced tyrosine phosphorylation of CD22. We propose that the cytoplasmic tail of CD22 contains two domains that regulate signal transduction pathways initiated by the BCR and B cell fate.
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Affiliation(s)
- K L Otipoby
- Department of Immunology, University of Washington, Seattle, Washington 98195, USA.
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43
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Kitazume S, Tachida Y, Oka R, Shirotani K, Saido TC, Hashimoto Y. Alzheimer's beta-secretase, beta-site amyloid precursor protein-cleaving enzyme, is responsible for cleavage secretion of a Golgi-resident sialyltransferase. Proc Natl Acad Sci U S A 2001; 98:13554-9. [PMID: 11698669 PMCID: PMC61079 DOI: 10.1073/pnas.241509198] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2001] [Accepted: 09/26/2001] [Indexed: 11/18/2022] Open
Abstract
The deposition of amyloid beta-peptide (A beta) in the brain is closely associated with the development of Alzheimer's disease. A beta is generated from the amyloid precursor protein (APP) by sequential action of beta-secretase (BACE1) and gamma-secretase. Although BACE1 is distributed among various other tissues, its physiological substrates other than APP have yet to be identified. ST6Gal I is a sialyltransferase that produces a sialyl alpha 2,6galactose residue, and the enzyme is secreted out of the cell after proteolytic cleavage. We report here that BACE1 is involved in the proteolytic cleavage of ST6Gal I, on the basis of the following observations. ST6Gal I was colocalized with BACE1 in the Golgi apparatus by immunofluorescence microscopy, suggesting that BACE1 acts on ST6Gal I within the same intracellular compartment. When BACE1 was overexpressed with ST6Gal I in COS cells, the secretion of ST6Gal I markedly increased. When APP(SW) (Swedish familial Alzheimer's disease mutation), a preferable substrate for BACE1, was coexpressed with ST6Gal I in COS cells, the secretion of ST6Gal I significantly decreased, suggesting that that the beta-cleavage of overexpressed APP(SW) competes with ST6Gal I processing. In addition, BACE1-Fc (Fc, the hinge and constant region of IgG) chimera cleaved protein A-ST6Gal I fusion protein in vitro. Thus, we conclude that BACE1 is responsible for the cleavage and secretion of ST6Gal I.
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Affiliation(s)
- S Kitazume
- Glyco-chain Functions Laboratory, Supra-biomolecular System Group, Frontier Research System, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
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44
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Affiliation(s)
- S Kelm
- Institute of Biochemistry, University of Kiel, Olshausenstrasse 40, 24098 Kiel, Germany
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45
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Liossis SN, Solomou EE, Dimopoulos MA, Panayiotidis P, Mavrikakis MM, Sfikakis PP. B-cell kinase lyn deficiency in patients with systemic lupus erythematosus. J Investig Med 2001; 49:157-65. [PMID: 11288756 DOI: 10.2310/6650.2001.34042] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND To better understand the molecular background of B-cell overactivity characterizing systemic lupus erythematosus (SLE), we examined the expression of the CD22 co-receptor and of kinase Lyn, which are involved in signaling inhibitory pathways, in B cells from patients with SLE. METHODS Two-color flow cytometry was used to study the expression of surface antigens on freshly isolated peripheral B cells from patients with SLE, disease-control patients, and healthy volunteers. Intracellular kinases Lyn and Syk were analyzed using Western immunoblots, and differences at the messenger RNA (mRNA) level were evaluated using semiquantitative polymerase chain reaction (PCR). RESULTS Expression of B-cell surface CD22 was intact in patients with SLE, but expression of the B-cell kinase Lyn was significantly decreased in resting, as well as in anti-sIgM-stimulated B-cell-enriched cell lysates obtained from 66% of patients with SLE. Lyn deficiency was disease-specific and unrelated to disease activity. Expression of B-cell kinase Syk was similar in all study groups. Semiquantitative PCR revealed that Lyn mRNA was significantly decreased in lupus patients with decreased Lyn protein expression, suggesting that Lyn deficiency may be caused at least in part by defects at the transcription level. CONCLUSIONS Decreased expression of Lyn in some patients with SLE represents a B-cell defect that may enhance our understanding of SLE molecular pathogenesis by providing rational therapeutic targets.
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Affiliation(s)
- S N Liossis
- First Department of Propedeutic Medicine, Athens University Medical School, Laikon Hospital, Greece.
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46
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Floyd H, Nitschke L, Crocker PR. A novel subset of murine B cells that expresses unmasked forms of CD22 is enriched in the bone marrow: implications for B-cell homing to the bone marrow. Immunology 2000; 101:342-7. [PMID: 11106937 PMCID: PMC2327092 DOI: 10.1046/j.1365-2567.2000.00103.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD22 is a B-cell-restricted transmembrane protein, which acts as a negative regulator of B-cell signalling. CD22 also has lectin-like adhesive properties. When expressed on transfected fibroblasts, it is capable of mediating adhesion to other cells via recognition of cell-surface glycoconjugates terminating in alpha2,6-linked sialic acids. In previous studies in the mouse, CD22 was implicated as a bone marrow homing receptor for recirculating immunoglobulin D+ (IgD+) B cells through recognition of sialylated ligands on marrow sinusoidal endothelium. As the adhesive function of CD22 can be masked when alpha2,6-linked sialic acids are co-expressed at the cell surface, the aim of the present study was to investigate whether recirculating B cells have unmasked forms of CD22 that could be involved in bone marrow homing. Using alpha2,6-sialyllactose coupled to biotinylated polyacrylamide as a probe for detection of unmasked CD22, we showed that approximately 2-5% of IgD+ murine B cells in the spleen and mesenteric lymph nodes were able to bind this synthetic ligand. In the bone marrow, however, the fraction of IgD+ B cells with unmasked CD22 was increased by two- to fivefold. B cells from CD22-deficient mice were not stained with the polyacrylamide probe, confirming that staining of B cells in wild-type mice was caused by CD22 and not by other potential sialic acid-binding lectins. In conclusion, we have identified a new subset of mature B cells in the mouse with unmasked CD22. This subset of recirculating B cells may bind to CD22 ligands on bone marrow sinusoidal endothelium, leading to their selective homing and subsequent enrichment in this tissue.
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Affiliation(s)
- H Floyd
- The Wellcome Trust Biocentre at Dundee, Department of Biochemistry, University of Dundee, Dundee, UK
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Zhang J, Somani AK, Siminovitch KA. Roles of the SHP-1 tyrosine phosphatase in the negative regulation of cell signalling. Semin Immunol 2000; 12:361-78. [PMID: 10995583 DOI: 10.1006/smim.2000.0223] [Citation(s) in RCA: 255] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The critical role for the SH2 domain-containing SHP-1 tyrosine phosphatase in regulating haemopoietic cell behaviour was initially revealed by data linking SHP-1 deficiency to the systemic autoimmunity and severe inflammation exhibited by motheaten mice. This discovery laid the groundwork for the identification of SHP-1 as an inhibitor of activation-promoting signalling cascades and for the coincident demonstration that protein tyrosine phosphatases (PTPs) such as SHP-1 show considerable specificity with respect to the mechanisms whereby they modulate the biochemical and biological sequelae of extracellular simulation. As outlined in this review, SHP-1 has now been implicated in the regulation of a myriad of signalling cascades and cell functions. As a result, the cumulative data generated from studies of this PTP have elucidated not only the functional relevance of SHP-1, but also a number of novel paradigms as to the molecular mechanisms whereby signalling cascades are regulated so as to either augment or abrogate specific cell behaviours.
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Affiliation(s)
- J Zhang
- Department of Medicine, University of Toronto, Ontario, Canada, M5G 1X5
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48
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Poe JC, Fujimoto M, Jansen PJ, Miller AS, Tedder TF. CD22 forms a quaternary complex with SHIP, Grb2, and Shc. A pathway for regulation of B lymphocyte antigen receptor-induced calcium flux. J Biol Chem 2000; 275:17420-7. [PMID: 10748054 DOI: 10.1074/jbc.m001892200] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD22 is a cell surface molecule that regulates signal transduction in B lymphocytes. Tyrosine-phosphorylated CD22 recruits numerous cytoplasmic effector molecules including SHP-1, a potent phosphotyrosine phosphatase that down-regulates B cell antigen receptor (BCR)- and CD19-generated signals. Paradoxically, B cells from CD22-deficient mice generate augmented intracellular calcium responses following BCR ligation, yet proliferation is decreased. To understand further the mechanisms through which CD22 regulates BCR-dependent calcium flux and proliferation, interactions between CD22 and effector molecules involved in these processes were assessed. The adapter proteins Grb2 and Shc were found to interact with distinct and specific regions of the CD22 cytoplasmic domain. Src homology-2 domain-containing inositol polyphosphate-5'-phosphatase (SHIP) also bound phosphorylated CD22, but binding required an intact CD22 cytoplasmic domain. All three molecules were bound to CD22 when isolated from BCR-stimulated splenic B cells, indicating the formation of a CD22.Grb2.Shc.SHIP quaternary complex. Therefore, SHIP associating with CD22 may be important for SHIP recruitment to the cell surface where it negatively regulates calcium influx. Although augmented calcium responses in CD22-deficient mice should facilitate enhanced c-Jun N-terminal kinase (JNK) activation, BCR ligation did not induce JNK activation in CD22-deficient B cells. These data demonstrate that CD22 functions as a molecular "scaffold" that specifically coordinates the docking of multiple effector molecules, in addition to SHP-1, in a context necessary for BCR-dependent SHIP activity and JNK stimulation.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adaptor Proteins, Vesicular Transport
- Amino Acid Sequence
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/chemistry
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- B-Lymphocytes/physiology
- Binding Sites
- Calcium/metabolism
- Cell Adhesion Molecules
- GRB2 Adaptor Protein
- JNK Mitogen-Activated Protein Kinases
- Lectins
- Macromolecular Substances
- Mice
- Mice, Knockout
- Mitogen-Activated Protein Kinases/metabolism
- Molecular Sequence Data
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
- Phosphoric Monoester Hydrolases/chemistry
- Phosphoric Monoester Hydrolases/metabolism
- Protein Structure, Quaternary
- Proteins/chemistry
- Proteins/metabolism
- Receptors, Antigen, B-Cell/physiology
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
- Shc Signaling Adaptor Proteins
- Sialic Acid Binding Ig-like Lectin 2
- Src Homology 2 Domain-Containing, Transforming Protein 1
- src Homology Domains
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Affiliation(s)
- J C Poe
- Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Tamir I, Dal Porto JM, Cambier JC. Cytoplasmic protein tyrosine phosphatases SHP-1 and SHP-2: regulators of B cell signal transduction. Curr Opin Immunol 2000; 12:307-15. [PMID: 10781410 DOI: 10.1016/s0952-7915(00)00092-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
One of the areas of greatest recent progress in immunology has been the elucidation of inhibitory receptors and their mode of signal transduction. A common feature of members of this growing family is expression of a conserved cytoplasmic sequence motif, the immunoreceptor tyrosine-based inhibitory motif, which functions to recruit and activate phosphatases that mediate the receptors' function. Family members include the protein tyrosine phosphatases SHP-1 (Src-homology-2-domain-containing protein tyrosine phosphatase 1) and SHP-2, which function to dephosphorylate key intermediaries in antigen receptor signaling pathways. Surprisingly, whereas most data to date support a role for SHP-1 in inhibitory signaling, SHP-2 exhibits distinct functions that appear to positively regulate receptor function.
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Affiliation(s)
- I Tamir
- Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA
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Adachi T, Wakabayashi C, Nakayama T, Yakura H, Tsubata T. CD72 negatively regulates signaling through the antigen receptor of B cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:1223-9. [PMID: 10640734 DOI: 10.4049/jimmunol.164.3.1223] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The immunoreceptor tyrosine-based inhibition motif (ITIM) is found in various membrane molecules such as CD22 and the low-affinity Fc receptor for IgG in B cells and the killer cell-inhibitory receptor and Ly-49 in NK cells. Upon tyrosine phosphorylation at the ITIMs, these molecules recruit SH2 domain-containing phosphatases such as SH2-containing tyrosine phosphatase-1 and negatively regulate cell activity. The B cell surface molecule CD72 carries an ITIM and an ITIM-like sequence. We have previously shown that CD72 is phosphorylated and recruits SH2-containing tyrosine phosphatase-1 upon cross-linking of the Ag receptor of B cells (BCR). However, whether CD72 modulates BCR signaling has not yet been elucidated. In this paper we demonstrate that expression of CD72 down-modulates both extracellular signal-related kinase (ERK) activation and Ca2+ mobilization induced by BCR ligation in the mouse B lymphoma line K46micromlambda, whereas BCR-mediated ERK activation was not reduced by the ITIM-mutated form of CD72. Moreover, coligation with CD72 with BCR reduces BCR-mediated ERK activation in spleen B cells of normal mice. These results indicate that CD72 negatively regulates BCR signaling. CD72 may play a regulatory role in B cell activation, probably by setting a threshold for BCR signaling.
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MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/immunology
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Antigens, Differentiation, B-Lymphocyte/physiology
- Calcium/metabolism
- Calcium Signaling/genetics
- Calcium Signaling/immunology
- Down-Regulation/genetics
- Down-Regulation/immunology
- Ligands
- Lymphoma, B-Cell/enzymology
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred DBA
- Mitogen-Activated Protein Kinases/metabolism
- Receptors, Antigen, B-Cell/immunology
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Antigen, B-Cell/physiology
- Signal Transduction/genetics
- Signal Transduction/immunology
- Spleen/cytology
- Spleen/immunology
- Spleen/metabolism
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- T Adachi
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Japan
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