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Bhanja A, Seeley-Fallen MK, Lazzaro M, Upadhyaya A, Song W. N-WASP-dependent branched actin polymerization attenuates B-cell receptor signaling by increasing the molecular density of receptor clusters. eLife 2023; 12:RP87833. [PMID: 38085658 PMCID: PMC10715734 DOI: 10.7554/elife.87833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023] Open
Abstract
Antigen-induced B-cell receptor (BCR) signaling is critical for initiating and regulating B-cell activation. The actin cytoskeleton plays essential roles in BCR signaling. Upon encountering cell-surface antigens, actin-driven B-cell spreading amplifies signaling, while B-cell contraction following spreading leads to signal attenuation. However, the mechanism by which actin dynamics switch BCR signaling from amplification to attenuation is unknown. Here, we show that Arp2/3-mediated branched actin polymerization is required for mouse splenic B-cell contraction. Contracting B-cells generate centripetally moving actin foci from lamellipodial F-actin networks in the plasma membrane region contacting antigen-presenting surfaces. Actin polymerization driven by N-WASP, but not WASP, initiates these actin foci and facilitates non-muscle myosin II recruitment to the contact zone, creating actomyosin ring-like structures. B-cell contraction increases BCR molecular density in individual clusters, leading to decreased BCR phosphorylation. Increased BCR molecular density reduced levels of the stimulatory kinase Syk, the inhibitory phosphatase SHIP-1, and their phosphorylated forms in individual BCR clusters. These results suggest that N-WASP-activated Arp2/3, coordinating with myosin, generates centripetally moving foci and contractile actomyosin ring-like structures from lamellipodial networks, enabling contraction. B-cell contraction attenuates BCR signaling by pushing out both stimulatory kinases and inhibitory phosphatases from BCR clusters, providing novel insights into actin-facilitated signal attenuation.
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Affiliation(s)
- Anshuman Bhanja
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Margaret K Seeley-Fallen
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Michelle Lazzaro
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Arpita Upadhyaya
- Biophysics Program, University of MarylandCollege ParkUnited States
- Department of Physics, University of MarylandCollege ParkUnited States
- Institute for Physical Science and Technology, University of MarylandCollege ParkUnited States
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
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2
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Bhanja A, Seeley-Fallen MK, Lazzaro M, Upadhyaya A, Song W. N-WASP-dependent branched actin polymerization attenuates B-cell receptor signaling by increasing the molecular density of receptor clusters. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532631. [PMID: 36993351 PMCID: PMC10055065 DOI: 10.1101/2023.03.14.532631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Antigen-induced B-cell receptor (BCR) signaling is critical for initiating and regulating B-cell activation. The actin cytoskeleton plays essential roles in BCR signaling. Upon encountering cell-surface antigens, actin-driven B-cell spreading amplifies signaling, while B-cell contraction following spreading leads to signal attenuation. However, the mechanism by which actin dynamics switch BCR signaling from amplification to attenuation is unknown. Here, we show that Arp2/3-mediated branched actin polymerization is required for B-cell contraction. Contracting B-cells generate centripetally moving actin foci from lamellipodial F-actin networks in the B-cell plasma membrane region contacting antigen-presenting surfaces. Actin polymerization driven by N-WASP, but not WASP, initiates these actin foci and facilitates non-muscle myosin II recruitment to the contact zone, creating actomyosin ring-like structures. Furthermore, B-cell contraction increases BCR molecular density in individual clusters, leading to decreased BCR phosphorylation. Increased BCR molecular density reduced levels of the stimulatory kinase Syk, the inhibitory phosphatase SHIP-1, and their phosphorylated forms in individual BCR clusters. These results suggest that N-WASP-activated Arp2/3, coordinating with myosin, generates centripetally moving foci and contractile actomyosin ring-like structures from lamellipodial networks, enabling contraction. B-cell contraction attenuates BCR signaling by pushing out both stimulatory kinases and inhibitory phosphatases from BCR clusters, providing novel insights into actin-facilitated signal attenuation.
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Affiliation(s)
- Anshuman Bhanja
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Margaret K. Seeley-Fallen
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Michelle Lazzaro
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Arpita Upadhyaya
- Biophysics Program, University of Maryland, College Park, MD, 20742, USA
- Department of Physics, University of Maryland, College Park, MD, 20742, USA
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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3
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Zhang E, Phan P, Zhao Z. Cellular nanovesicles for therapeutic immunomodulation: A perspective on engineering strategies and new advances. Acta Pharm Sin B 2022; 13:1789-1827. [DOI: 10.1016/j.apsb.2022.08.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/11/2022] [Accepted: 07/28/2022] [Indexed: 02/08/2023] Open
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4
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Wang JC, Yim YI, Wu X, Jaumouille V, Cameron A, Waterman CM, Kehrl JH, Hammer JA. A B-cell actomyosin arc network couples integrin co-stimulation to mechanical force-dependent immune synapse formation. eLife 2022; 11:e72805. [PMID: 35404237 PMCID: PMC9142150 DOI: 10.7554/elife.72805] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 04/10/2022] [Indexed: 11/13/2022] Open
Abstract
B-cell activation and immune synapse (IS) formation with membrane-bound antigens are actin-dependent processes that scale positively with the strength of antigen-induced signals. Importantly, ligating the B-cell integrin, LFA-1, with ICAM-1 promotes IS formation when antigen is limiting. Whether the actin cytoskeleton plays a specific role in integrin-dependent IS formation is unknown. Here, we show using super-resolution imaging of mouse primary B cells that LFA-1:ICAM-1 interactions promote the formation of an actomyosin network that dominates the B-cell IS. This network is created by the formin mDia1, organized into concentric, contractile arcs by myosin 2A, and flows inward at the same rate as B-cell receptor (BCR):antigen clusters. Consistently, individual BCR microclusters are swept inward by individual actomyosin arcs. Under conditions where integrin is required for synapse formation, inhibiting myosin impairs synapse formation, as evidenced by reduced antigen centralization, diminished BCR signaling, and defective signaling protein distribution at the synapse. Together, these results argue that a contractile actomyosin arc network plays a key role in the mechanism by which LFA-1 co-stimulation promotes B-cell activation and IS formation.
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Affiliation(s)
- Jia C Wang
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Yang-In Yim
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Xufeng Wu
- Light Microscopy Core, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Valentin Jaumouille
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Andrew Cameron
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Clare M Waterman
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - John H Kehrl
- B Cell Molecular Immunology Section, National Institutes of Allergy and Infectious Diseases, National Institutes of HealthBethesdaUnited States
| | - John A Hammer
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
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5
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Meena M, Van Delen M, De Laere M, Sterkens A, Costas Romero C, Berneman Z, Cools N. Transmigration across a Steady-State Blood-Brain Barrie Induces Activation of Circulating Dendritic Cells Partly Mediated by Actin Cytoskeletal Reorganization. MEMBRANES 2021; 11:membranes11090700. [PMID: 34564517 PMCID: PMC8472465 DOI: 10.3390/membranes11090700] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 12/16/2022]
Abstract
The central nervous system (CNS) is considered to be an immunologically unique site, in large part given its extensive protection by the blood–brain barrier (BBB). As our knowledge of the complex interaction between the peripheral immune system and the CNS expands, the mechanisms of immune privilege are being refined. Here, we studied the interaction of dendritic cells (DCs) with the BBB in steady–state conditions and observed that transmigrated DCs display an activated phenotype and stronger T cell-stimulatory capacity as compared to non-migrating DCs. Next, we aimed to gain further insights in the processes underlying activation of DCs following transmigration across the BBB. We investigated the interaction of DCs with endothelial cells as well as the involvement of actin cytoskeletal reorganization. Whereas we were not able to demonstrate that DCs engulf membrane fragments from fluorescently labelled endothelial cells during transmigration across the BBB, we found that blocking actin restructuring of DCs by latrunculin-A significantly impaired in vitro migration of DC across the BBB and subsequent T cell-stimulatory capacity, albeit no effect on migration-induced phenotypic activation could be demonstrated. These observations contribute to the current understanding of the interaction between DCs and the BBB, ultimately leading to the design of targeted therapies capable to inhibit autoimmune inflammation of the CNS.
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Affiliation(s)
- Megha Meena
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
| | - Mats Van Delen
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
| | - Maxime De Laere
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
- Center for Cell Therapy and Regenerative Medicine, Laboratory of Experimental Hematology, Antwerp University Hospital, 2650 Edegem, Belgium
| | - Ann Sterkens
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
- Department of Dermatology, Antwerp University Hospital, 2650 Edegem, Belgium
| | - Coloma Costas Romero
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
| | - Zwi Berneman
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
- Center for Cell Therapy and Regenerative Medicine, Laboratory of Experimental Hematology, Antwerp University Hospital, 2650 Edegem, Belgium
| | - Nathalie Cools
- Laboratory of Experimental Hematology, Vaccine & Infectious Disease Institute (VAXINFECTIO), Faculty of Medicine and Health Sciences, University of Antwerp, 2610 Wilrijk, Belgium; (M.M.); (M.V.D.); (M.D.L.); (A.S.); (C.C.R.); (Z.B.)
- Center for Cell Therapy and Regenerative Medicine, Laboratory of Experimental Hematology, Antwerp University Hospital, 2650 Edegem, Belgium
- Correspondence:
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6
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Ibañez-Vega J, Del Valle F, Sáez JJ, Guzman F, Diaz J, Soza A, Yuseff MI. Ecm29-Dependent Proteasome Localization Regulates Cytoskeleton Remodeling at the Immune Synapse. Front Cell Dev Biol 2021; 9:650817. [PMID: 34055780 PMCID: PMC8155528 DOI: 10.3389/fcell.2021.650817] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/14/2021] [Indexed: 12/25/2022] Open
Abstract
The formation of an immune synapse (IS) enables B cells to capture membrane-tethered antigens, where cortical actin cytoskeleton remodeling regulates cell spreading and depletion of F-actin at the centrosome promotes the recruitment of lysosomes to facilitate antigen extraction. How B cells regulate both pools of actin, remains poorly understood. We report here that decreased F-actin at the centrosome and IS relies on the distribution of the proteasome, regulated by Ecm29. Silencing Ecm29 decreases the proteasome pool associated to the centrosome of B cells and shifts its accumulation to the cell cortex and IS. Accordingly, Ecm29-silenced B cells display increased F-actin at the centrosome, impaired centrosome and lysosome repositioning to the IS and defective antigen extraction and presentation. Ecm29-silenced B cells, which accumulate higher levels of proteasome at the cell cortex, display decreased actin retrograde flow in lamellipodia and enhanced spreading responses. Our findings support a model where B the asymmetric distribution of the proteasome, mediated by Ecm29, coordinates actin dynamics at the centrosome and the IS, promoting lysosome recruitment and cell spreading.
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Affiliation(s)
- Jorge Ibañez-Vega
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Felipe Del Valle
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan José Sáez
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fanny Guzman
- Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Jheimmy Diaz
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Andrea Soza
- Centro de Biología Celular y Biomedicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
- Centro de Envejecimiento y Regeneración (CARE), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - María Isabel Yuseff
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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7
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Adamo A, Brandi J, Caligola S, Delfino P, Bazzoni R, Carusone R, Cecconi D, Giugno R, Manfredi M, Robotti E, Marengo E, Bassi G, Takam Kamga P, Dal Collo G, Gatti A, Mercuri A, Arigoni M, Olivero M, Calogero RA, Krampera M. Extracellular Vesicles Mediate Mesenchymal Stromal Cell-Dependent Regulation of B Cell PI3K-AKT Signaling Pathway and Actin Cytoskeleton. Front Immunol 2019; 10:446. [PMID: 30915084 PMCID: PMC6423067 DOI: 10.3389/fimmu.2019.00446] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/19/2019] [Indexed: 12/11/2022] Open
Abstract
Mesenchymal stromal cells (MSCs) are adult, multipotent cells of mesodermal origin representing the progenitors of all stromal tissues. MSCs possess significant and broad immunomodulatory functions affecting both adaptive and innate immune responses once MSCs are primed by the inflammatory microenvironment. Recently, the role of extracellular vesicles (EVs) in mediating the therapeutic effects of MSCs has been recognized. Nevertheless, the molecular mechanisms responsible for the immunomodulatory properties of MSC-derived EVs (MSC-EVs) are still poorly characterized. Therefore, we carried out a molecular characterization of MSC-EV content by high-throughput approaches. We analyzed miRNA and protein expression profile in cellular and vesicular compartments both in normal and inflammatory conditions. We found several proteins and miRNAs involved in immunological processes, such as MOES, LG3BP, PTX3, and S10A6 proteins, miR-155-5p, and miR-497-5p. Different in silico approaches were also performed to correlate miRNA and protein expression profile and then to evaluate the putative molecules or pathways involved in immunoregulatory properties mediated by MSC-EVs. PI3K-AKT signaling pathway and the regulation of actin cytoskeleton were identified and functionally validated in vitro as key mediators of MSC/B cell communication mediated by MSC-EVs. In conclusion, we identified different molecules and pathways responsible for immunoregulatory properties mediated by MSC-EVs, thus identifying novel therapeutic targets as safer and more useful alternatives to cell or EV-based therapeutic approaches.
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Affiliation(s)
- Annalisa Adamo
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Jessica Brandi
- Proteomics and Mass Spectrometry Laboratory, Department of Biotechnology, University of Verona, Verona, Italy
| | - Simone Caligola
- Department of Computer Science, University of Verona, Verona, Italy
| | - Pietro Delfino
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Riccardo Bazzoni
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Roberta Carusone
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Daniela Cecconi
- Proteomics and Mass Spectrometry Laboratory, Department of Biotechnology, University of Verona, Verona, Italy
| | - Rosalba Giugno
- Department of Computer Science, University of Verona, Verona, Italy
| | - Marcello Manfredi
- Department of Sciences and Technological Innovation, University of Piemonte Orientale, Alessandria, Italy.,Center for Translational Research on Autoimmune and Allergic Diseases (CAAD), Novara, Italy
| | - Elisa Robotti
- Department of Sciences and Technological Innovation, University of Piemonte Orientale, Alessandria, Italy
| | - Emilio Marengo
- Department of Sciences and Technological Innovation, University of Piemonte Orientale, Alessandria, Italy.,Center for Translational Research on Autoimmune and Allergic Diseases (CAAD), Novara, Italy
| | - Giulio Bassi
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Paul Takam Kamga
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Giada Dal Collo
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Alessandro Gatti
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Angela Mercuri
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
| | - Maddalena Arigoni
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Turin, Italy
| | | | - Raffaele A Calogero
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Turin, Italy
| | - Mauro Krampera
- Stem Cell Research Laboratory, Section of Hematology, Department of Medicine, University of Verona, Verona, Italy
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8
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Abstract
B cells are essential to the adaptive immune system for providing the humoral immunity against cohorts of pathogens. The presentation of antigen to the B cell receptor (BCR) leads to the initiation of B cell activation, which is a process sensitive to the stiffness features of the substrates presenting the antigens. Mechanosensing of the B cells, potentiated through BCR signaling and the adhesion molecules, efficiently regulates B cell activation, proliferation and subsequent antibody responses. Defects in sensing of the antigen-presenting substrates can lead to the activation of autoreactive B cells in autoimmune diseases. The use of high-resolution, high-speed live-cell imaging along with the sophisticated biophysical materials, has uncovered the mechanisms underlying the initiation of B cell activation within seconds of its engagement with the antigen presenting substrates. In this chapter, we reviewed studies that have contributed to uncover the molecular mechanisms of B cell mechanosensing during the initiation of B cell activation.
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Affiliation(s)
- Samina Shaheen
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Zhengpeng Wan
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Kabeer Haneef
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Yingyue Zeng
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Wang Jing
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Wanli Liu
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China.
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9
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Amitai A, Chakraborty AK, Kardar M. The low spike density of HIV may have evolved because of the effects of T helper cell depletion on affinity maturation. PLoS Comput Biol 2018; 14:e1006408. [PMID: 30161121 PMCID: PMC6150518 DOI: 10.1371/journal.pcbi.1006408] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 09/21/2018] [Accepted: 07/31/2018] [Indexed: 12/11/2022] Open
Abstract
The spikes on virus surfaces bind receptors on host cells to propagate infection. High spike densities (SDs) can promote infection, but spikes are also targets of antibody-mediated immune responses. Thus, diverse evolutionary pressures can influence virus SDs. HIV's SD is about two orders of magnitude lower than that of other viruses, a surprising feature of unknown origin. By modeling antibody evolution through affinity maturation, we find that an intermediate SD maximizes the affinity of generated antibodies. We argue that this leads most viruses to evolve high SDs. T helper cells, which are depleted during early HIV infection, play a key role in antibody evolution. We find that T helper cell depletion results in high affinity antibodies when SD is high, but not if SD is low. This special feature of HIV infection may have led to the evolution of a low SD to avoid potent immune responses early in infection.
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Affiliation(s)
- Assaf Amitai
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Arup K. Chakraborty
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Mehran Kardar
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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10
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Ketchum CM, Sun X, Suberi A, Fourkas JT, Song W, Upadhyaya A. Subcellular topography modulates actin dynamics and signaling in B-cells. Mol Biol Cell 2018; 29:1732-1742. [PMID: 29771636 PMCID: PMC6080708 DOI: 10.1091/mbc.e17-06-0422] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
B-cell signaling activation is most effectively triggered by the binding of B-cell receptors (BCRs) to membrane-bound antigens. In vivo, B-cells encounter antigen on antigen-presenting cells (APC), which possess complex surfaces with convoluted topographies, a fluid membrane and deformable cell bodies. However, whether and how the physical properties of antigen presentation affect B-cell activation is not well understood. Here we use nanotopographic surfaces that allow systematic variation of geometric parameters to show that surface features on a subcellular scale influence B-cell signaling and actin dynamics. Parallel nanoridges with spacings of 3 microns or greater induce actin intensity oscillations on the ventral cell surface. Nanotopography-induced actin dynamics requires BCR signaling, actin polymerization, and myosin contractility. The topography of the stimulatory surface also modulates the distribution of BCR clusters in activated B-cells. Finally, B-cells stimulated on nanopatterned surfaces exhibit intracellular calcium oscillations with frequencies that depend on topography. Our results point to the importance of physical aspects of ligand presentation, in particular, nanotopography for B-cell activation and antigen gathering.
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Affiliation(s)
| | - Xiaoyu Sun
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - Alexandra Suberi
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - John T Fourkas
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742.,Center for Nanophysics and Advanced Materials, University of Maryland, College Park, MD 20742.,Maryland NanoCenter, University of Maryland, College Park, MD 20742
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Arpita Upadhyaya
- Biophysics Program, University of Maryland, College Park, MD 20742.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742.,Department of Physics, University of Maryland, College Park, MD 20742
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11
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Wang JC, Bolger-Munro M, Gold MR. Visualizing the Actin and Microtubule Cytoskeletons at the B-cell Immune Synapse Using Stimulated Emission Depletion (STED) Microscopy. J Vis Exp 2018. [PMID: 29683438 DOI: 10.3791/57028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
B cells that bind to membrane-bound antigens (e.g., on the surface of an antigen-presenting cell) form an immune synapse, a specialized cellular structure that optimizes B-cell receptor (BCR) signaling and BCR-mediated antigen acquisition. Both the remodeling of the actin cytoskeleton and the reorientation of the microtubule network towards the antigen contact site are essential for immune synapse formation. Remodeling of the actin cytoskeleton into a dense peripheral ring of F-actin is accompanied by polarization of the microtubule-organizing center towards the immune synapse. Microtubule plus-end binding proteins, as well as cortical plus-end capture proteins mediate physical interactions between the actin and microtubule cytoskeletons, which allow them to be reorganized in a coordinated manner. Elucidating the mechanisms that control this cytoskeletal reorganization, as well as understanding how these cytoskeletal structures shape immune synapse formation and BCR signaling, can provide new insights into B cell activation. This has been aided by the development of super-resolution microscopy approaches that reveal new details of cytoskeletal network organization. We describe here a method for using stimulated emission depletion (STED) microscopy to simultaneously image actin structures, microtubules, and transfected GFP-tagged microtubule plus-end binding proteins in B cells. To model the early events in immune synapse formation, we allow B cells to spread on coverslips coated with anti-immunoglobulin (anti-Ig) antibodies, which initiate BCR signaling and cytoskeleton remodeling. We provide step-by-step protocols for expressing GFP fusion proteins in A20 B-lymphoma cells, for anti-Ig-induced cell spreading, and for subsequent cell fixation, Immunostaining, image acquisition, and image deconvolution steps. The high-resolution images obtained using these procedures allow one to simultaneously visualize actin structures, microtubules, and the microtubule plus-end binding proteins that may link these two cytoskeletal networks.
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Affiliation(s)
- Jia C Wang
- Department of Microbiology and Immunology, University of British Columbia
| | | | - Michael R Gold
- Department of Microbiology and Immunology, University of British Columbia;
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12
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Wang JC, Lee JYJ, Dang-Lawson M, Pritchard C, Gold MR. The Rap2c GTPase facilitates B cell receptor-induced reorientation of the microtubule-organizing center. Small GTPases 2018; 11:402-412. [PMID: 29457987 DOI: 10.1080/21541248.2018.1441626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
When B lymphocytes encounter antigen-bearing surfaces, B-cell receptor (BCR) signaling initiates remodeling of the F-actin network and reorientation of the microtubule-organizing center (MTOC) towards the antigen contact site. We have previously shown that the Rap1 GTPase, an evolutionarily conserved regulator of cell polarity, is essential for these processes and that Rap1-regulated actin remodeling is required for MTOC polarization. The role of Rap2 proteins in establishing cell polarity is not well understood. We now show that depleting Rap2c, the only Rap2 isoform expressed in the A20 B-cell line, impairs BCR-induced MTOC reorientation as well as the actin remodeling that supports MTOC polarization. Thus Rap1 and Rap2 proteins may have similar but non-redundant functions in coupling the BCR to MTOC polarization.
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Affiliation(s)
- Jia C Wang
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia , Vancouver, BC, Canada
| | - Jeff Y-J Lee
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia , Vancouver, BC, Canada
| | - May Dang-Lawson
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia , Vancouver, BC, Canada
| | - Caitlin Pritchard
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia , Vancouver, BC, Canada
| | - Michael R Gold
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia , Vancouver, BC, Canada
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13
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Rey I, Garcia DA, Wheatley BA, Song W, Upadhyaya A. Biophysical Techniques to Study B Cell Activation: Single-Molecule Imaging and Force Measurements. Methods Mol Biol 2018; 1707:51-68. [PMID: 29388099 DOI: 10.1007/978-1-4939-7474-0_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells of the adaptive immune system recognize pathogenic peptides through specialized receptors on their membranes. The engagement of these receptors with antigen leads to cell activation, which induces profound changes in the cell including cytoskeleton remodeling and membrane deformation. During this process, receptors and signaling molecules undergo spatiotemporal reorganization to form signaling microclusters and the immunological synapse. The cytoskeletal and membrane dynamics also leads to exertion of forces on the cell-substrate interface. In this chapter we describe two techniques-one for single-molecule imaging of B cell receptors to measure their diffusive properties as cells get activated on supported lipid bilayers; and the second for visualizing and quantifying cellular forces using elastic surfaces to stimulate T and B cells.
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Affiliation(s)
- Ivan Rey
- Biophysics Program, University of Maryland, College Park, MD, 20742, USA
| | - David A Garcia
- Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | | | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Arpita Upadhyaya
- Biophysics Program, University of Maryland, College Park, MD, 20742, USA. .,Department of Physics, University of Maryland, College Park, MD, 20742, USA. .,Institute for Physical Science and Technology, University of Maryland, 1151, PSC Bldg., College Park, MD, 20742, USA.
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14
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Mechanosensing in the immune response. Semin Cell Dev Biol 2017; 71:137-145. [PMID: 28830744 DOI: 10.1016/j.semcdb.2017.08.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/11/2017] [Accepted: 08/14/2017] [Indexed: 01/16/2023]
Abstract
Cells have a remarkable ability to sense and respond to the mechanical properties of their environment. Mechanosensing is essential for many phenomena, ranging from cell movements and tissue rearrangements to cell differentiation and the immune response. Cells of the immune system get activated when membrane receptors bind to cognate antigen on the surface of antigen presenting cells. Both T and B lymphocyte signaling has been shown to be responsive to physical forces and mechanical cues. Cytoskeletal forces exerted by cells likely mediate this mechanical modulation. Here, we discuss recent advances in the field of immune cell mechanobiology at the molecular and cellular scale.
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15
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Wang JC, Lee JYJ, Christian S, Dang-Lawson M, Pritchard C, Freeman SA, Gold MR. The Rap1-cofilin-1 pathway coordinates actin reorganization and MTOC polarization at the B cell immune synapse. J Cell Sci 2017; 130:1094-1109. [PMID: 28167682 DOI: 10.1242/jcs.191858] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 01/31/2017] [Indexed: 12/19/2022] Open
Abstract
B cells that bind antigens displayed on antigen-presenting cells (APCs) form an immune synapse, a polarized cellular structure that optimizes the dual functions of the B cell receptor (BCR), signal transduction and antigen internalization. Immune synapse formation involves polarization of the microtubule-organizing center (MTOC) towards the APC. We now show that BCR-induced MTOC polarization requires the Rap1 GTPase (which has two isoforms, Rap1a and Rap1b), an evolutionarily conserved regulator of cell polarity, as well as cofilin-1, an actin-severing protein that is regulated by Rap1. MTOC reorientation towards the antigen contact site correlated strongly with cofilin-1-dependent actin reorganization and cell spreading. We also show that BCR-induced MTOC polarization requires the dynein motor protein as well as IQGAP1, a scaffolding protein that can link the actin and microtubule cytoskeletons. At the periphery of the immune synapse, IQGAP1 associates closely with F-actin structures and with the microtubule plus-end-binding protein CLIP-170 (also known as CLIP1). Moreover, the accumulation of IQGAP1 at the antigen contact site depends on F-actin reorganization that is controlled by Rap1 and cofilin-1. Thus the Rap1-cofilin-1 pathway coordinates actin and microtubule organization at the immune synapse.
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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, British Columbia, Canada V6T 1Z3
| | - Jeff Y-J Lee
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Sonja Christian
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - May Dang-Lawson
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Caitlin Pritchard
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Spencer A Freeman
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Michael R Gold
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
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16
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Lu X, Guo H, Chen X, Xiao J, Zou Y, Wang W, Chen Q. Effect of RhoC on the epithelial-mesenchymal transition process induced by TGF-β1 in lung adenocarcinoma cells. Oncol Rep 2016; 36:3105-3112. [PMID: 27748883 PMCID: PMC5112615 DOI: 10.3892/or.2016.5146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/31/2016] [Indexed: 12/30/2022] Open
Abstract
According to recent research, Ras homolog gene family member C (RhoC) is confirmed to have a powerful regulatory effect on cell motility mediated by the cytoskeleton, and this process is closely associated with tumor invasion and metastasis. In addition, the epithelial-mesenchymal transition (EMT) process which causes cytoskeleton rearrangement, also plays a pivotal role in tumor invasion and metastasis.Consequently, in the present study, we aimed to ascertain whether RhoC has an effect on the EMT process induced by TGF-β1 in lung adenocarcinoma cells and whether RhoC promotes tumor invasion by mediating the occurrence of EMT. Based on the findings, we demonstrated that RhoC was an essential mediator of the EMT process in lung adenocarcinoma cell line A549 which was evaluated by observing the morphological characteristics of the cells and by assessing the expression levels of two EMT marker proteins: E-cadherin and vimentin. During the process of EMT in the A549 cells induced by TGF-β1 (5 ng/ml), upregulated RhoC protein and RhoC activity were detected, which was associated with the enhanced invasive capability of the cells in vitro. Conversely, downregulation of the expression of RhoC by shRNA markedly impeded EMT progression as well as the invasion of A549 cells. Our results may provide a novel target towards the prevention of metastasis in advanced lung adenocarcinoma.
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Affiliation(s)
- Xiaoxiao Lu
- Department of Geriatrics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Honglan Guo
- Department of Geriatrics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Xi Chen
- Department of Respiratory Medicine, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Jian Xiao
- Department of Geriatrics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Yong Zou
- Department of Geriatrics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Wei Wang
- Department of Nephrology Medicine, Huaihe Hospital of Henan University, Kaifeng, Henan 475000, P.R. China
| | - Qiong Chen
- Department of Geriatrics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
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17
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Finkenstaedt-Quinn SA, Qiu TA, Shin K, Haynes CL. Super-resolution imaging for monitoring cytoskeleton dynamics. Analyst 2016; 141:5674-5688. [PMID: 27549146 DOI: 10.1039/c6an00731g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cytoskeleton is a key cellular structure that is important in the control of cellular movement, structure, and sensing. To successfully image the individual cytoskeleton components, high resolution and super-resolution fluorescence imaging methods are needed. This review covers the three basic cytoskeletal elements and the relative benefits and drawbacks of fixed versus live cell imaging before moving on to recent studies using high resolution and super-resolution techniques. The techniques covered include the near-diffraction limited imaging methods of confocal microscopy and TIRF microscopy and the super-resolution fluorescence imaging methods of STORM, PALM, and STED.
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18
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Levit-Zerdoun E, Becker M, Pohlmeyer R, Wilhelm I, Maity PC, Rajewsky K, Reth M, Hobeika E. Survival of Igα-Deficient Mature B Cells Requires BAFF-R Function. THE JOURNAL OF IMMUNOLOGY 2016; 196:2348-60. [PMID: 26843325 DOI: 10.4049/jimmunol.1501707] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 12/29/2015] [Indexed: 12/18/2022]
Abstract
Expression of a functional BCR is essential for the development of mature B cells and has been invoked in the control of their maintenance. To test this maintenance function in a new experimental setting, we used the tamoxifen-inducible mb1-CreER(T2) mouse strain to delete or truncate either the mb-1 gene encoding the BCR signaling subunit Igα or the VDJ segment of the IgH (H chain [HC]). In this system, Cre-mediated deletion of the mb-1 gene is accompanied by expression of a GFP reporter. We found that, although the Igα-deficient mature B cells survive for >20 d in vivo, the HC-deficient or Igα tail-truncated B cell population is short-lived, with the HC-deficient cells displaying signs of an unfolded protein response. We also show that Igα-deficient B cells still respond to the prosurvival factor BAFF in culture and require BAFF-R signaling for their in vivo maintenance. These results suggest that, under certain conditions, the loss of the BCR can be tolerated by mature B cells for some time, whereas HC-deficient B cells, potentially generated by aberrant somatic mutations in the germinal center, are rapidly eliminated.
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Affiliation(s)
- Ella Levit-Zerdoun
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology, 79108 Freiburg, Germany
| | - Martin Becker
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology, 79108 Freiburg, Germany
| | - Roland Pohlmeyer
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Isabel Wilhelm
- Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Palash Chandra Maity
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Klaus Rajewsky
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; and
| | - Michael Reth
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany;
| | - Elias Hobeika
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; Institute of Immunology, University Hospital Ulm, 89081 Ulm, Germany
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19
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Pala F, Morbach H, Castiello MC, Schickel JN, Scaramuzza S, Chamberlain N, Cassani B, Glauzy S, Romberg N, Candotti F, Aiuti A, Bosticardo M, Villa A, Meffre E. Lentiviral-mediated gene therapy restores B cell tolerance in Wiskott-Aldrich syndrome patients. J Clin Invest 2015; 125:3941-51. [PMID: 26368308 DOI: 10.1172/jci82249] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/16/2015] [Indexed: 11/17/2022] Open
Abstract
Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency characterized by microthrombocytopenia, eczema, and high susceptibility to developing tumors and autoimmunity. Recent evidence suggests that B cells may be key players in the pathogenesis of autoimmunity in WAS. Here, we assessed whether WAS protein deficiency (WASp deficiency) affects the establishment of B cell tolerance by testing the reactivity of recombinant antibodies isolated from single B cells from 4 WAS patients before and after gene therapy (GT). We found that pre-GT WASp-deficient B cells were hyperreactive to B cell receptor stimulation (BCR stimulation). This hyperreactivity correlated with decreased frequency of autoreactive new emigrant/transitional B cells exiting the BM, indicating that the BCR signaling threshold plays a major role in the regulation of central B cell tolerance. In contrast, mature naive B cells from WAS patients were enriched in self-reactive clones, revealing that peripheral B cell tolerance checkpoint dysfunction is associated with impaired suppressive function of WAS regulatory T cells. The introduction of functional WASp by GT corrected the alterations of both central and peripheral B cell tolerance checkpoints. We conclude that WASp plays an important role in the establishment and maintenance of B cell tolerance in humans and that restoration of WASp by GT is able to restore B cell tolerance in WAS patients.
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20
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Abstract
Aggregation of the high-affinity IgE receptor (FcεRI) on the plasma membrane of mast cells and basophils initiates signaling events leading to a rapid release of preformed inflammatory mediators from secretory granules, and overall changes in cell morphology. Mast cell activation also causes reorganization of cytoskeletal components associated with membrane ruffling, spreading, and migration. Here we describe methods used for visualization of mast cell cytoskeleton, focusing on its two major components, microfilaments and microtubules, and their changes after cell triggering.
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21
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Pore D, Bodo J, Danda A, Yan D, Phillips JG, Lindner D, Hill BT, Smith MR, Hsi ED, Gupta N. Identification of Ezrin-Radixin-Moesin proteins as novel regulators of pathogenic B-cell receptor signaling and tumor growth in diffuse large B-cell lymphoma. Leukemia 2015; 29:1857-67. [PMID: 25801911 PMCID: PMC4558318 DOI: 10.1038/leu.2015.86] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 03/18/2015] [Accepted: 03/19/2015] [Indexed: 02/07/2023]
Abstract
Diffuse large B-cell lymphoma (DLBCL) is a hematological cancer associated with an aggressive clinical course. The predominant subtypes of DLBCL display features of chronic or tonic B-cell antigen receptor (BCR) signaling. However, it is not known whether the spatial organization of the BCR contributes to the regulation of pro-survival signaling pathways and cell growth. Here, we show that primary DLBCL tumors and patient-derived DLBCL cell lines contain high levels of phosphorylated Ezrin-Radixin-Moesin (ERM) proteins. The surface BCRs in both activated B cell and germinal B cell subtype DLBCL cells co-segregate with phosphoERM suggesting that the cytoskeletal network may support localized BCR signaling and contribute to pathogenesis. Indeed, ablation of membrane-cytoskeletal linkages by dominant-negative mutants, pharmacological inhibition and knockdown of ERM proteins disrupted cell surface BCR organization, inhibited proximal and distal BCR signaling, and reduced the growth of DLBCL cell lines. In vivo administration of the ezrin inhibitor retarded the growth of DLBCL tumor xenografts, concomitant with reduction in intratumor phosphoERM levels, dampened pro-survival signaling and induction of apoptosis. Our results reveal a novel ERM-based spatial mechanism that is coopted by DLBCL cells to sustain tumor cell growth and survival.
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Affiliation(s)
- D Pore
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - J Bodo
- Department of Clinical Pathology, Institute of Pathology and Laboratory Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - A Danda
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - D Yan
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - J G Phillips
- Department of Translational Hematology and Oncology Research, Cleveland Clinic, Cleveland, OH, USA
| | - D Lindner
- Department of Translational Hematology and Oncology Research, Cleveland Clinic, Cleveland, OH, USA
| | - B T Hill
- Department of Hematology and Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
| | - M R Smith
- Department of Hematology and Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
| | - E D Hsi
- Department of Clinical Pathology, Institute of Pathology and Laboratory Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - N Gupta
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
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22
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Iliuk A, Jayasundera K, Wang WH, Schluttenhofer R, Geahlen RL, Tao WA. In-Depth Analyses of B Cell Signaling Through Tandem Mass Spectrometry of Phosphopeptides Enriched by PolyMAC. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2015; 377:744-753. [PMID: 25954137 PMCID: PMC4417941 DOI: 10.1016/j.ijms.2014.08.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Tandem mass spectrometry (MS/MS) has enabled researchers to analyze complex biological samples since the original concept inception. It facilitates the identification and quantification of modifications within tens of thousands of proteins in a single large-scale proteomic experiment. Phosphorylation analysis, as one of the most common and important post-translational modifications, has particularly benefited from such progress in the field. Here we showcase the technique through in-depth analyses of B cell signaling based on quantitative phosphoproteomics. As a complement to the previously described PolyMAC-Ti (polymer-based metal ion affinity capture using titanium) reagent, we introduce here PolyMAC-Fe, which utilizes a different metal ion, Fe(III). An extensive comparison using the different available MS/MS fragmentations techniques was made between PolyMAC-Fe, PolyMAC-Ti and IMAC (immobilized metal ion affinity chromatography) reagents in terms of specificity, reproducibility and type of phosphopeptides being enriched. PolyMAC-Fe based chelation demonstrated good selectivity and unique specificity toward phosphopeptides, making it useful in specialized applications. We have combined PolyMAC-Ti and PolyMAC-Fe, along with SILAC-based quantitation and large-scale fractionation, for quantitative B cell phosphoproteomic analyses. The complementary approach allowed us to identify a larger percentage of multiply phosphorylated peptides than with PolyMAC-Ti alone. Overall, out of 13,794 unique phosphorylation sites identified, close to 20% were dependent on BCR signaling. These sites were further mapped to a variety of major signaling networks, offering more detailed information about the biochemistry of B cell receptor engagement.
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Affiliation(s)
- Anton Iliuk
- Department of Biochemistry, Purdue University, West Lafayette, IN 47906
- Tymora Analytical Operations, LLC. 1281 Win Hentschel Blvd., West Lafayette, IN 47906
| | | | - Wen-Horng Wang
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, IN 47907
| | | | - Robert L. Geahlen
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, IN 47907
| | - W. Andy Tao
- Department of Biochemistry, Purdue University, West Lafayette, IN 47906
- Tymora Analytical Operations, LLC. 1281 Win Hentschel Blvd., West Lafayette, IN 47906
- Department of Chemistry, Purdue University, West Lafayette, IN 47907
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, IN 47907
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23
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Brusilovsky M, Radinsky O, Cohen L, Yossef R, Shemesh A, Braiman A, Mandelboim O, Campbell KS, Porgador A. Regulation of natural cytotoxicity receptors by heparan sulfate proteoglycans in -cis: A lesson from NKp44. Eur J Immunol 2015; 45:1180-91. [PMID: 25546090 DOI: 10.1002/eji.201445177] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 12/21/2014] [Accepted: 12/23/2014] [Indexed: 11/06/2022]
Abstract
NKp44 (NCR2) is a distinct member of natural cytotoxicity receptors (NCRs) family that can induce cytokine production and cytolytic activity in human NK cells. Heparan sulfate proteoglycans (HSPGs) are differentially expressed in various normal and cancerous tissues. HSPGs were reported to serve as ligands/co-ligands for NKp44 and other NCRs. However, HSPG expression is not restricted to either group and can be found also in NK cells. Our current study reveals that NKp44 function can be modulated through interactions with HSPGs on NK cells themselves in -cis rather than on target cells in -trans. The intimate interaction of NKp44 and the NK cell-associated HSPG syndecan-4 (SDC4) in -cis can directly regulate membrane distribution of NKp44 and constitutively dampens the triggering of the receptor. We further demonstrate, that the disruption of NKp44 and SDC4 interaction releases the receptor to engage with its ligands in -trans and therefore enhances NKp44 activation potential and NK cell functional response.
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Affiliation(s)
- Michael Brusilovsky
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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24
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Eisen HN. Affinity enhancement of antibodies: how low-affinity antibodies produced early in immune responses are followed by high-affinity antibodies later and in memory B-cell responses. Cancer Immunol Res 2014; 2:381-92. [PMID: 24795350 DOI: 10.1158/2326-6066.cir-14-0029] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The antibodies produced initially in response to most antigens are high molecular weight (MW) immunoglobulins (IgM) with low affinity for the antigen, while the antibodies produced later are lower MW classes (e.g., IgG and IgA) with, on average, orders of magnitude higher affinity for that antigen. These changes, often termed affinity maturation, take place largely in small B-cell clusters (germinal center; GC) in lymphoid tissues in which proliferating antigen-stimulated B cells express the highly mutagenic cytidine deaminase that mediates immunoglobulin class-switching and sequence diversification of the immunoglobulin variable domains of antigen-binding receptors on B cells (BCR). Of the large library of BCR-mutated B cells thus rapidly generated, a small minority with affinity-enhancing mutations are selected to survive and differentiate into long-lived antibody-secreting plasma cells and memory B cells. BCRs are also endocytic receptors; they internalize and cleave BCR-bound antigen, yielding peptide-MHC complexes that are recognized by follicular helper T cells. Imperfect correlation between BCR affinity for antigen and cognate T-cell engagement may account for the increasing affinity heterogeneity that accompanies the increasing average affinity of antibodies. Conservation of mechanisms underlying mutation and selection of high-affinity antibodies over the ≈200 million years of evolution separating bird and mammal lineages points to the crucial role of antibody affinity enhancement in adaptive immunity.
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Affiliation(s)
- Herman N Eisen
- Authors' Affiliations: Ragon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts
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Königsberger S, Weis V, Prodöhl J, Stehling M, Hobeika E, Reth M, Kiefer F. Suboptimal B-cell antigen receptor signaling activity in vivo elicits germinal center counterselection mechanisms. Eur J Immunol 2014; 45:603-11. [PMID: 25382621 DOI: 10.1002/eji.201444538] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 10/22/2014] [Accepted: 11/05/2014] [Indexed: 12/14/2022]
Abstract
Syk and Zap-70 constitute a closely related nonreceptor protein tyrosine kinase family, of which both members are functionally indispensable for conferring their respective antigen receptors with enzymatic activity. In this study, we analyze the impact of altering BCR signaling output on B-cell germinal center (GC) fate selection by constitutive, as well as inducible, monoallelic Syk kinase loss in the presence of a Zap-70 knock-in rescue allele. Cre-mediated Syk deletion in Syk(flox/Zap-70) B cells lowers pErk, but not pAkt-mediated signaling. Surprisingly, the use of a B-cell-specific constitutive mb1-cre deleter mouse model showed that a small cohort of peripheral Syk(flox/Zap-70);mb1-cre B cells efficiently circumvents deletion, which ultimately favors these Syk-sufficient cells to contribute to the GC reaction. Using a developmentally unbiased Syk(flox/Zap-70);mb1-creER(T2) approach in combination with an inducible tdRFP allele, we further demonstrate that this monoallelic deletion escape is not fully explained by leakiness of Cre expression, but is possibly the result of differential Syk locus accessibility in maturing B cells. Altogether, this underscores the importance of proper Syk kinase function not only during central and peripheral selection processes, but also during GC formation and maintenance.
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Affiliation(s)
- Sebastian Königsberger
- Max Planck Institute for Molecular Biomedicine, Mammalian Cell Signaling Laboratory, Münster, Germany
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Roberts MEP, Kaminski D, Jenks SA, Maguire C, Ching K, Burbelo PD, Iadarola MJ, Rosenberg A, Coca A, Anolik J, Sanz I. Primary Sjögren's syndrome is characterized by distinct phenotypic and transcriptional profiles of IgD+ unswitched memory B cells. Arthritis Rheumatol 2014; 66:2558-69. [PMID: 24909310 DOI: 10.1002/art.38734] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Accepted: 05/29/2014] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The significance of distinct B cell abnormalities in primary Sjögren's syndrome (SS) remains to be established. We undertook this study to analyze the phenotype and messenger RNA (mRNA) transcript profiles of B cell subsets in patients with primary SS and to compare them with those in sicca syndrome patients and healthy controls. METHODS CD19+ B cells from 26 patients with primary SS, 27 sicca syndrome patients, and 22 healthy controls were analyzed by flow cytometry. Gene expression profiles of purified B cell subsets (from 3-5 subjects per group per test) were analyzed using Affymetrix gene arrays. RESULTS Patients with primary SS had lower frequencies of CD27+IgD- switched memory B cells and CD27+IgD+ unswitched memory B cells compared with healthy controls. Unswitched memory B cell frequencies were also lower in sicca syndrome patients and correlated inversely with serologic hyperactivity in both disease states. Further, unswitched memory B cells in primary SS had lower expression of CD1c and CD21. Gene expression analysis of CD27+ memory B cells separated patients with primary SS from healthy controls and identified a subgroup of sicca syndrome patients with a primary SS-like transcript profile. Moreover, unswitched memory B cell gene expression analysis identified 187 genes differentially expressed between patients with primary SS and healthy controls. CONCLUSION A decrease in unswitched memory B cells with serologic hyperactivity is characteristic of both established primary SS and a subgroup of sicca syndrome, which suggests the value of these B cells both as biomarkers of future disease progression and for understanding disease pathogenesis. Overall, the mRNA transcript analysis of unswitched memory B cells suggests that their activation in primary SS takes place through innate immune pathways in the context of attenuated antigen-mediated adaptive signaling. Thus, our findings provide important insight into the mechanisms and potential consequences of decreased unswitched memory B cells in primary SS.
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Baraitser-Winter cerebrofrontofacial syndrome: delineation of the spectrum in 42 cases. Eur J Hum Genet 2014; 23:292-301. [PMID: 25052316 DOI: 10.1038/ejhg.2014.95] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 04/05/2014] [Accepted: 04/30/2014] [Indexed: 11/08/2022] Open
Abstract
Baraitser-Winter, Fryns-Aftimos and cerebrofrontofacial syndrome types 1 and 3 have recently been associated with heterozygous gain-of-function mutations in one of the two ubiquitous cytoplasmic actin-encoding genes ACTB and ACTG1 that encode β- and γ-actins. We present detailed phenotypic descriptions and neuroimaging on 36 patients analyzed by our group and six cases from the literature with a molecularly proven actinopathy (9 ACTG1 and 33 ACTB). The major clinical anomalies are striking dysmorphic facial features with hypertelorism, broad nose with large tip and prominent root, congenital non-myopathic ptosis, ridged metopic suture and arched eyebrows. Iris or retinal coloboma is present in many cases, as is sensorineural deafness. Cleft lip and palate, hallux duplex, congenital heart defects and renal tract anomalies are seen in some cases. Microcephaly may develop with time. Nearly all patients with ACTG1 mutations, and around 60% of those with ACTB mutations have some degree of pachygyria with anteroposterior severity gradient, rarely lissencephaly or neuronal heterotopia. Reduction of shoulder girdle muscle bulk and progressive joint stiffness is common. Early muscular involvement, occasionally with congenital arthrogryposis, may be present. Progressive, severe dystonia was seen in one family. Intellectual disability and epilepsy are variable in severity and largely correlate with CNS anomalies. One patient developed acute lymphocytic leukemia, and another a cutaneous lymphoma, indicating that actinopathies may be cancer-predisposing disorders. Considering the multifaceted role of actins in cell physiology, we hypothesize that some clinical manifestations may be partially mutation specific. Baraitser-Winter cerebrofrontofacial syndrome is our suggested designation for this clinical entity.
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Santos-Argumedo L, Maravillas-Montero JL, López-Ortega O. Class I myosins in B-cell physiology: functions in spreading, immune synapses, motility, and vesicular traffic. Immunol Rev 2014; 256:190-202. [PMID: 24117822 DOI: 10.1111/imr.12105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myosins comprise a family of motor proteins whose role in muscle contraction and motility in a large range of eukaryotic cells has been widely studied. Although these proteins have been characterized extensively and much is known about their function in different cellular compartments, little is known about these molecules in hematopoietic cells. Myosins expressed by cells from the immune response are involved in maintaining plasma membrane tension, moving and secreting vesicles, endo- and exocytotic processes, and promoting the adhesion and motility of cells. Herein, we summarize our current understanding of class I myosins in B cells, with an emphasis on the emerging roles of these molecular motors in immune functions.
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Abstract
Tight regulation of actin dynamics is essential for T-cell trafficking and activation. Recent studies in human and murine T cells reveal that T-cell motility and full T-cell activation require the hematopoietic-specific, actin-bundling protein L-plastin (LPL). T cells lacking LPL do not form fully mature synapses and thus demonstrate reduced cytokine production and proliferation. Reduction or loss of LPL expression also reduces the velocity of T cells and impairs thymic egress and intranodal motility. Whereas dispensable for proximal T-cell receptor and chemokine receptor signaling, LPL is critical to the later stages of synapse maturation and cellular polarization. Serine phosphorylation, calcium, and calmodulin binding regulate the bundling activity and localization of LPL following T-cell receptor and chemokine receptor engagement. However, the interaction between these regulatory domains and resulting changes in local control of actin cytoskeletal structures has not been fully elucidated. Circumstantial evidence suggests a function for LPL in either the formation or maintenance of integrin-associated adhesion structures. As LPL may be a target of the commonly used immunosuppressive agent dexamethasone, full elucidation of the regulation and function of LPL in T-cell biology may illuminate new pathways for clinically useful immunotherapeutics.
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Affiliation(s)
- Sharon Celeste Morley
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
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Tóth B, Pistár Z, Csorba G, Balogh I, Kovács T, Erdős M, Maródi L. Novel dedicator of cytokinesis 8 mutations identified by multiplex ligation-dependent probe amplification. Eur J Haematol 2013; 91:369-75. [PMID: 23859592 DOI: 10.1111/ejh.12173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 01/04/2023]
Abstract
Dedicator of cytokinesis 8 (DOCK8) deficiency is an innate error of adaptive immunity characterized by recurrent infections with viruses, bacteria and fungi, very high serum IgE concentrations, and a progressive deterioration of T- and B-cell-mediated immunity. We studied the genetic and immunological features of two sisters (aged 11 and 6 yr). Mutational analysis of genomic DNA and cDNA from the patients and their parents, by a combination of PCR and bidirectional targeted sequencing, failed to localize the mutation site. However, a multiplex ligation-dependent probe amplification (MLPA) assay revealed two novel large deletions, del1-14 exons and del8-18 exons, of DOCK8 in both patients. Immunoblot analysis demonstrated that DOCK8 protein was absent from the peripheral blood lymphocytes of both patients. These data suggest that compound heterozygous del1-14 exons and del8-18 exons mutations result in a loss of function of DOCK8 protein and a typical DOCK8 deficiency phenotype.
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Affiliation(s)
- Beáta Tóth
- Department of Infectious and Pediatric Immunology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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New insights into pre-BCR and BCR signalling with relevance to B cell malignancies. Nat Rev Immunol 2013; 13:578-91. [DOI: 10.1038/nri3487] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Parameswaran N, Enyindah-Asonye G, Bagheri N, Shah NB, Gupta N. Spatial coupling of JNK activation to the B cell antigen receptor by tyrosine-phosphorylated ezrin. THE JOURNAL OF IMMUNOLOGY 2013; 190:2017-26. [PMID: 23338238 DOI: 10.4049/jimmunol.1201292] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The ezrin-radixin-moesin proteins regulate B lymphocyte activation via their effect on BCR diffusion and microclustering. This relies on their ability to dynamically tether the plasma membrane with actin filaments that is in turn facilitated by phosphorylation of the conserved threonine residue in the actin-binding domain. In this study, we describe a novel function of ezrin in regulating JNK activation that is mediated by phosphorylation of a tyrosine (Y353) residue that is unconserved with moesin and radixin. BCR, but not CD40, TLR4, or CXCR5 stimulation, induced phosphorylation of ezrin at Y353 in mouse splenic B cells. Ezrin existed in a preformed complex with Syk in unstimulated B cells and underwent Syk-dependent phosphorylation upon anti-IgM stimulation. Y353-phosphorylated ezrin colocalized with the BCR within minutes of stimulation and cotrafficked with the endocytosed BCRs through the early and late endosomes. The T567 residue of ezrin was rephosphorylated in late endosomes and at the plasma membrane at later times of BCR stimulation. Expression of a nonphosphorylatable Y353F mutant of ezrin specifically impaired JNK activation. BCR crosslinking induced the association of Y353-phosphorylated ezrin with JNK and its kinase MAPKK7, as well as spatial colocalization with phosphorylated JNK in the endosomes. The yellow fluorescent protein-tagged Y353F mutant displayed reduced colocalization with the endocytosed BCR as compared with wild-type ezrin-yellow fluorescent protein. Taken together, our data identify a novel role for ezrin as a spatial adaptor that couples JNK signaling components to the BCR signalosome, thus facilitating JNK activation.
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Affiliation(s)
- Neetha Parameswaran
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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Sherman E, Barr V, Samelson LE. Super-resolution characterization of TCR-dependent signaling clusters. Immunol Rev 2013; 251:21-35. [PMID: 23278738 PMCID: PMC3539238 DOI: 10.1111/imr.12010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Multi-molecular signaling complexes drive the earliest events of immune cell activation via immunoreceptors with unexplained specificity and speed. Fluorescence microscopy has shown that these complexes form microclusters at the plasma membrane of activated T cells upon engagement of their antigen receptors (TCRs). Although crucial for cell function, much remains to be learned about the molecular content, fine structure, formation mechanisms, and function of these microclusters. Recent advancements in super-resolution microscopy have enabled the study of signaling microclusters at the single molecule level with resolution down to approximately 20 nm. These techniques have now helped to characterize the size distributions of signaling clusters at the plasma membrane of intact cells and to shed light on the formation mechanisms that govern their assembly. Surprisingly, dynamic and functional nanostructures have been identified within the signaling clusters. We expect that these novel methodologies, combined with older techniques, will shed new light on the nature of signaling clusters and their critical role in T-cell activation.
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Affiliation(s)
- Eilon Sherman
- Laboratory of Cellular and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892-4256, USA.
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Catucci M, Castiello MC, Pala F, Bosticardo M, Villa A. Autoimmunity in wiskott-Aldrich syndrome: an unsolved enigma. Front Immunol 2012; 3:209. [PMID: 22826711 PMCID: PMC3399097 DOI: 10.3389/fimmu.2012.00209] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 07/01/2012] [Indexed: 12/17/2022] Open
Abstract
Wiskott-Aldrich Syndrome (WAS) is a severe X-linked Primary Immunodeficiency that affects 1-10 out of 1 million male individuals. WAS is caused by mutations in the WAS Protein (WASP) expressing gene that leads to the absent or reduced expression of the protein. WASP is a cytoplasmic protein that regulates the formation of actin filaments in hematopoietic cells. WASP deficiency causes many immune cell defects both in humans and in the WAS murine model, the Was(-/-) mouse. Both cellular and humoral immune defects in WAS patients contribute to the onset of severe clinical manifestations, in particular microthrombocytopenia, eczema, recurrent infections, and a high susceptibility to develop autoimmunity and malignancies. Autoimmune diseases affect from 22 to 72% of WAS patients and the most common manifestation is autoimmune hemolytic anemia, followed by vasculitis, arthritis, neutropenia, inflammatory bowel disease, and IgA nephropathy. Many groups have widely explored immune cell functionality in WAS partially explaining how cellular defects may lead to pathology. However, the mechanisms underlying the occurrence of autoimmune manifestations have not been clearly described yet. In the present review, we report the most recent progresses in the study of immune cell function in WAS that have started to unveil the mechanisms contributing to autoimmune complications in WAS patients.
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Affiliation(s)
- Marco Catucci
- San Raffaele Telethon Institute for Gene Therapy (HSR-TIGET) Milan, Italy
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WIP remodeling actin behind the scenes: how WIP reshapes immune and other functions. Int J Mol Sci 2012; 13:7629-7647. [PMID: 22837718 PMCID: PMC3397550 DOI: 10.3390/ijms13067629] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 06/07/2012] [Accepted: 06/14/2012] [Indexed: 01/09/2023] Open
Abstract
Actin polymerization is a fundamental cellular process regulating immune cell functions and the immune response. The Wiskott-Aldrich syndrome protein (WASp) is an actin nucleation promoting factor, which is exclusively expressed in hematopoietic cells, where it plays a key regulatory role in cytoskeletal dynamics. WASp interacting protein (WIP) was first discovered as the binding partner of WASp, through the use of the yeast two hybrid system. WIP was later identified as a chaperone of WASp, necessary for its stability. Mutations occurring at the WASp homology 1 domain (WH1), which serves as the WIP binding site, were found to cause the Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). WAS manifests as an immune deficiency characterized by eczema, thrombocytopenia, recurrent infections, and hematopoietic malignancies, demonstrating the importance of WIP for WASp complex formation and for a proper immune response. WIP deficiency was found to lead to different abnormalities in the activity of various lymphocytes, suggesting differential cell-dependent roles for WIP. Additionally, WIP deficiency causes cellular abnormalities not found in WASp-deficient cells, indicating that WIP fulfills roles beyond stabilizing WASp. Indeed, WIP was shown to interact with various binding partners, including the signaling proteins Nck, CrkL and cortactin. Recent studies have demonstrated that WIP also takes part in non immune cellular processes such as cancer invasion and metastasis, in addition to cell subversion by intracellular pathogens. Understanding of numerous functions of WIP can enhance our current understanding of activation and function of immune and other cell types.
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Sengupta P, Lippincott-Schwartz J. Quantitative analysis of photoactivated localization microscopy (PALM) datasets using pair-correlation analysis. Bioessays 2012; 34:396-405. [PMID: 22447653 PMCID: PMC3659788 DOI: 10.1002/bies.201200022] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Pointillistic based super-resolution techniques, such as photoactivated localization microscopy (PALM), involve multiple cycles of sequential activation, imaging, and precise localization of single fluorescent molecules. A super-resolution image, having nanoscopic structural information, is then constructed by compiling all the image sequences. Because the final image resolution is determined by the localization precision of detected single molecules and their density, accurate image reconstruction requires imaging of biological structures labeled with fluorescent molecules at high density. In such image datasets, stochastic variations in photon emission and intervening dark states lead to uncertainties in identification of single molecules. This, in turn, prevents the proper utilization of the wealth of information on molecular distribution and quantity. A recent strategy for overcoming this problem is pair-correlation analysis applied to PALM. Using rigorous statistical algorithms to estimate the number of detected proteins, this approach allows the spatial organization of molecules to be quantitatively described.
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Affiliation(s)
- Prabuddha Sengupta
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MA, USA.
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The actin-bundling protein L-plastin: a critical regulator of immune cell function. Int J Cell Biol 2011; 2012:935173. [PMID: 22194750 PMCID: PMC3238366 DOI: 10.1155/2012/935173] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 10/12/2011] [Indexed: 01/08/2023] Open
Abstract
L-plastin is a leukocyte-specific protein that cross-links actin filaments into tight bundles, increasing the stability of actin-based structures such as podosomes and lamellipodia. While first identified as an abundant cytoplasmic protein in hematopoietically derived cells over 25 years ago, the requirement for L-plastin in multiple functions critical for immunity, such as antigen receptor signaling, adhesion, and motility, has only recently become clear. L-plastin has been identified as an important component in cellular processes critical for neutrophil, macrophage, osteoclast, eosinophil, and T- and B-lymphocyte biology. Following a brief description of the structure and function of L-plastin, the regulation of immune cell functions by L-plastin will be reviewed in detail.
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Freeman SA, Lei V, Dang-Lawson M, Mizuno K, Roskelley CD, Gold MR. Cofilin-Mediated F-Actin Severing Is Regulated by the Rap GTPase and Controls the Cytoskeletal Dynamics That Drive Lymphocyte Spreading and BCR Microcluster Formation. THE JOURNAL OF IMMUNOLOGY 2011; 187:5887-900. [DOI: 10.4049/jimmunol.1102233] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Sengupta P, Jovanovic-Talisman T, Skoko D, Renz M, Veatch SL, Lippincott-Schwartz J. Probing protein heterogeneity in the plasma membrane using PALM and pair correlation analysis. Nat Methods 2011; 8:969-75. [PMID: 21926998 DOI: 10.1038/nmeth.1704] [Citation(s) in RCA: 424] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 08/16/2011] [Indexed: 01/07/2023]
Abstract
Photoactivated localization microscopy (PALM) is a powerful approach for investigating protein organization, yet tools for quantitative, spatial analysis of PALM datasets are largely missing. Combining pair-correlation analysis with PALM (PC-PALM), we provide a method to analyze complex patterns of protein organization across the plasma membrane without determination of absolute protein numbers. The approach uses an algorithm to distinguish a single protein with multiple appearances from clusters of proteins. This enables quantification of different parameters of spatial organization, including the presence of protein clusters, their size, density and abundance in the plasma membrane. Using this method, we demonstrate distinct nanoscale organization of plasma-membrane proteins with different membrane anchoring and lipid partitioning characteristics in COS-7 cells, and show dramatic changes in glycosylphosphatidylinositol (GPI)-anchored protein arrangement under varying perturbations. PC-PALM is thus an effective tool with broad applicability for analysis of protein heterogeneity and function, adaptable to other single-molecule strategies.
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Affiliation(s)
- Prabuddha Sengupta
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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von Holleben M, Gohla A, Janssen KP, Iritani BM, Beer-Hammer S. Immunoinhibitory adapter protein Src homology domain 3 lymphocyte protein 2 (SLy2) regulates actin dynamics and B cell spreading. J Biol Chem 2011; 286:13489-501. [PMID: 21296879 DOI: 10.1074/jbc.m110.155184] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Appropriate B cell activation is essential for adaptive immunity. In contrast to the molecular mechanisms that regulate positive signaling in immune responses, the counterbalancing negative regulatory pathways remain insufficiently understood. The Src homology domain 3 (SH3)-containing adapter protein SH3 lymphocyte protein 2 (SLy2, also known as hematopoietic adapter-containing SH3 and sterile α-motif (SAM) domains 1; HACS1) is strongly up-regulated upon B cell activation and functions as an endogenous immunoinhibitor in vivo, but the underlying molecular mechanisms of SLy2 function have been elusive. We have generated transgenic mice overexpressing SLy2 in B and T cells and have studied the biological effects of elevated SLy2 levels in Jurkat and HeLa cells. Our results demonstrate that SLy2 induces Rac1-dependent membrane ruffle formation and regulates cell spreading and polarization and that the SLy2 SH3 domain is essential for these effects. Using immunoprecipitation and confocal microscopy, we provide evidence that the actin nucleation-promoting factor cortactin is an SH3 domain-directed interaction partner of SLy2. Consistent with an important role of SLy2 for actin cytoskeletal reorganization, we further show that SLy2-transgenic B cells are severely defective in cell spreading. Together, our findings extend our mechanistic understanding of the immunoinhibitory roles of SLy2 in vivo and suggest that the physiological up-regulation of SLy2 observed upon B cell activation functions to counteract excessive B cell spreading.
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Affiliation(s)
- Max von Holleben
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University, 40225 Duesseldorf, Germany
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Elliott LCC, Barhoum M, Harris JM, Bohn PW. Trajectory analysis of single molecules exhibiting non-Brownian motion. Phys Chem Chem Phys 2011; 13:4326-34. [DOI: 10.1039/c0cp01805h] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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