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Malinova D, Wasim L, Newman R, Martínez-Riaño A, Engels N, Tolar P. Endophilin A2 regulates B-cell endocytosis and is required for germinal center and humoral responses. EMBO Rep 2021; 22:e51328. [PMID: 34323351 PMCID: PMC8419706 DOI: 10.15252/embr.202051328] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 06/22/2021] [Accepted: 07/09/2021] [Indexed: 12/26/2022] Open
Abstract
Antigen‐specific B‐cell responses require endosomal trafficking to regulate antigen uptake and presentation to helper T cells, and to control expression and signaling of immune receptors. However, the molecular composition of B‐cell endosomal trafficking pathways and their specific roles in B‐cell responses have not been systematically investigated. Here, we report high‐throughput identification of genes regulating B‐cell receptor (BCR)‐mediated antigen internalization using genome‐wide functional screens. We show that antigen internalization depends both on constitutive, clathrin‐mediated endocytosis and on antigen‐induced, clathrin‐independent endocytosis mediated by endophilin A2. Although endophilin A2‐mediated endocytosis is dispensable for antigen presentation, it is selectively required for metabolic support of B‐cell proliferation, in part through regulation of iron uptake. Consequently, endophilin A2‐deficient mice show defects in GC B‐cell responses and production of high‐affinity IgG. The requirement for endophilin A2 highlights a unique importance of clathrin‐independent intracellular trafficking in GC B‐cell clonal expansion and antibody responses.
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Affiliation(s)
- Dessislava Malinova
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK.,Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Laabiah Wasim
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK
| | - Rebecca Newman
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK
| | - Ana Martínez-Riaño
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK
| | - Niklas Engels
- Institute of Cellular & Molecular Immunology, University Medical Center Göttingen, Göttingen, Germany
| | - Pavel Tolar
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, UK.,Institute of Immunity and Transplantation, University College London, London, UK
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2
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Liang T, Guo Y, Li M, Ding C, Sang S, Zhou T, Shao Q, Liu X, Lu J, Ji Z, Wang T, Kang Q. Cytoskeleton protein 4.1R regulates B-cell fate by modulating the canonical NF-κB pathway. Immunology 2020; 161:314-324. [PMID: 32852059 DOI: 10.1111/imm.13250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 06/16/2020] [Accepted: 08/12/2020] [Indexed: 11/29/2022] Open
Abstract
During the immune response, B cells can enter the memory pathway, which is characterized by class switch recombination (CSR), or they may undergo plasma cell differentiation (PCD) to secrete immunoglobulin. Both of these processes occur in activated B cells, which are reported to relate to membrane-association proteins and adaptors. Protein 4.1R acts as an adaptor, linking membrane proteins to the cytoskeleton, and is involved in many cell events such as cell activation and differentiation, and cytokine secretion. However, the effect of 4.1R on regulating B-cell fate is unclear. Here, we show an important association between B-cell fate and 4.1R. In vitro, primary B cells were stimulated with lipopolysaccharide combined with interleukin-4; results showed that 4.1R-deficient (4.1R-/- ) cells compared with wild-type (4.1R+/+ ) B cells augmented expression of activation-induced cytidine deaminase and germline, resulting in increased IgG1+ B cells, whereas the secretion of IgG1 and IgM was reduced, and CD138+ B cells were also decreased. Throughout the process, 4.1R regulated canonical nuclear factor (NF-κB) rather than non-canonical NF-κB to promote the expression of CSR complex components, leading to up-regulation of B-cell CSR. In contrast, 4.1R-deficient B cells showed reduced expression of Blimp-1, which caused B cells to down-regulate PCD. Furthermore, over-activation of canonical NF-κB may induce apoptosis signaling to cause PCD apoptosis to reduce PCD number. In summary, our results suggest that 4.1R acts as a B-cell fate regulator by inhibiting the canonical NF-κB signaling pathway.
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Affiliation(s)
- Taotao Liang
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Yuying Guo
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Mengjia Li
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Cong Ding
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Siyao Sang
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Tingting Zhou
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Qi Shao
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Xin Liu
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Jike Lu
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Zhenyu Ji
- Henan Academy of Medical and Pharmaceutical Sciences, Zhengzhou, China
| | - Ting Wang
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Qiaozhen Kang
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
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3
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Ambegaonkar AA, Kwak K, Sohn H, Manzella-Lapeira J, Brzostowski J, Pierce SK. Expression of inhibitory receptors by B cells in chronic human infectious diseases restricts responses to membrane-associated antigens. SCIENCE ADVANCES 2020; 6:eaba6493. [PMID: 32754637 PMCID: PMC7380957 DOI: 10.1126/sciadv.aba6493] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 06/11/2020] [Indexed: 05/10/2023]
Abstract
Chronic human infectious diseases, including malaria, are associated with a large expansion of a phenotypically and transcriptionally distinct subpopulation of B cells distinguished by their high expression of a variety of inhibitory receptors including FcγRIIB. Because these B cells, termed atypical memory B cells (MBCs), are unable to respond to soluble antigens, it was suggested that they contributed to the poor acquisition of immunity in chronic infections. Here, we show that the high expression of FcγRIIB restricts atypical MBC responses to membrane-associated antigens that function to actively exclude FcγRIIB from the B cell immune synapse and include the co-receptor CD19, allowing B cell antigen receptor signaling and differentiation toward plasma cells. Thus, chronic infectious diseases result in the expansion of B cells that robustly respond to antigens that associate with cell surfaces, such as antigens in immune complexes, but are unable to respond to fully soluble antigens, such as self-antigens.
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4
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Hui E. Understanding T cell signaling using membrane reconstitution. Immunol Rev 2020; 291:44-56. [PMID: 31402497 DOI: 10.1111/imr.12767] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 04/02/2019] [Indexed: 12/31/2022]
Abstract
T cells are central players of our immune system, as their functions range from killing tumorous and virus-infected cells to orchestrating the entire immune response. In order for T cells to divide and execute their functions, they must be activated by antigen-presenting cells (APCs) through a cell-cell junction. Extracellular interactions between receptors on T cells and their ligands on APCs trigger signaling cascades comprised of protein-protein interactions, enzymatic reactions, and spatial reorganization events, to either stimulate or repress T cell activation. Plasma membrane is the major platform for T cell signaling. Recruitment of cytosolic proteins to membrane-bound receptors is a common critical step in many signaling pathways. Membranes decrease the dimensionality of protein-protein interactions to enable weak yet biologically important interactions. Membrane resident proteins can phase separate into micro-islands that promote signaling by enriching or excluding signal regulators. Moreover, some membrane lipids can either mediate or regulate cell signaling by interacting with signaling proteins. While it is critical to investigate T cell signaling in a cellular environment, the large number of signaling pathways involved and potential crosstalk have made it difficult to obtain precise, quantitative information on T cell signaling. Reconstitution of purified proteins to model membranes provides a complementary avenue for T cell signaling research. Here, I review recent progress in studying T cell signaling using membrane reconstitution approaches.
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Affiliation(s)
- Enfu Hui
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, California
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5
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Roper SI, Wasim L, Malinova D, Way M, Cox S, Tolar P. B cells extract antigens at Arp2/3-generated actin foci interspersed with linear filaments. eLife 2019; 8:48093. [PMID: 31815664 PMCID: PMC6917489 DOI: 10.7554/elife.48093] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 12/02/2019] [Indexed: 12/20/2022] Open
Abstract
Antibody production depends on B cell internalization and presentation of antigens to helper T cells. To acquire antigens displayed by antigen-presenting cells, B cells form immune synapses and extract antigens by the mechanical activity of the acto-myosin cytoskeleton. While cytoskeleton organization driving the initial formation of the B cell synapse has been studied, how the cytoskeleton supports antigen extraction remains poorly understood. Here we show that after initial cell spreading, F-actin in synapses of primary mouse B cells and human B cell lines forms a highly dynamic pattern composed of actin foci interspersed with linear filaments and myosin IIa. The foci are generated by Arp2/3-mediated branched-actin polymerization and stochastically associate with antigen clusters to mediate internalization. However, antigen extraction also requires the activity of formins, which reside near the foci and produce the interspersed filaments. Thus, a cooperation of branched-actin foci supported by linear filaments underlies B cell mechanics during antigen extraction.
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Affiliation(s)
- Sophie I Roper
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Laabiah Wasim
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Dessislava Malinova
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, United Kingdom.,Division of Immunology and Inflammation, Department of Medicine, Imperial College London, London, United Kingdom
| | - Michael Way
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Susan Cox
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Pavel Tolar
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London, United Kingdom.,Division of Immunology and Inflammation, Department of Medicine, Imperial College London, London, United Kingdom
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6
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Ambegaonkar AA, Nagata S, Pierce SK, Sohn H. The Differentiation in vitro of Human Tonsil B Cells With the Phenotypic and Functional Characteristics of T-bet+ Atypical Memory B Cells in Malaria. Front Immunol 2019; 10:852. [PMID: 31068937 PMCID: PMC6491666 DOI: 10.3389/fimmu.2019.00852] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 04/02/2019] [Indexed: 01/14/2023] Open
Abstract
Malaria is a deadly infectious disease associated with fundamental changes in the composition of the memory B cell (MBC) compartment, most notably a large expansion of T-bet+ MBCs, termed atypical MBCs. However, we know little about the precursors of atypical MBCs and the conditions that drive their differentiation. We compared the responses of human tonsil naïve B cells, MBCs, and germinal center B cells to a variety of stimulatory conditions. We determined that prolonged antigen presentation in the presence of CpG and IFN-γ induced maximal expression of T-bet and other phenotypic markers of malaria-associated atypical MBCs primarily in naïve B cells in vitro. Importantly T-bet+ naïve-derived B cells resembled atypical MBCs in their hypo-responsiveness to signaling through their B cell receptors. Thus, naïve B cells can be induced to differentiate into phenotypically and functionally atypical-like MBCs in vitro under conditions that may prevail in chronic infectious diseases in vivo.
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Affiliation(s)
- Abhijit A Ambegaonkar
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Satoshi Nagata
- Center for Drug Design Research, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan
| | - Susan K Pierce
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Haewon Sohn
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
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7
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Wang JC, Bolger-Munro M, Gold MR. Imaging the Interactions Between B Cells and Antigen-Presenting Cells. Methods Mol Biol 2018; 1707:131-161. [PMID: 29388105 DOI: 10.1007/978-1-4939-7474-0_10] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In vivo, B cells are often activated by antigens that are displayed on the surface of antigen-presenting cells (APCs). Binding of membrane-associated antigens to the B cell receptor (BCR) causes rapid cytoskeleton-dependent changes in the spatial organization of the BCR and other B cell membrane proteins, leading to the formation of an immune synapse. This process has been modeled using antigens attached to artificial planar lipid bilayers or to plasma membrane sheets. As a more physiological system for studying B cell-APC interactions, we have expressed model antigens in easily transfected adherent cell lines such as Cos-7 cells. The model antigens that we have used are a transmembrane form of a single-chain anti-Igκ antibody and a transmembrane form of hen egg lysozyme that is fused to a fluorescent protein. This has allowed us to study multiple aspects of B cell immune synapse formation including cytoskeletal reorganization, BCR microcluster coalescence, BCR-mediated antigen gathering, and BCR signaling. Here, we provide protocols for expressing these model antigens on the surface of Cos-7 cells, transfecting B cells with siRNAs or with plasmids encoding fluorescent proteins, using fixed cell and live cell fluorescence microscopy to image B cell-APC interactions, and quantifying APC-induced changes in BCR spatial organization and signaling.
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Affiliation(s)
- Jia C Wang
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Madison Bolger-Munro
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Michael R Gold
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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