1
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Susa KJ, Bradshaw GA, Eisert RJ, Schilling CM, Kalocsay M, Blacklow SC, Kruse AC. A spatiotemporal map of co-receptor signaling networks underlying B cell activation. Cell Rep 2024; 43:114332. [PMID: 38850533 PMCID: PMC11256977 DOI: 10.1016/j.celrep.2024.114332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Revised: 04/16/2024] [Accepted: 05/23/2024] [Indexed: 06/10/2024] Open
Abstract
The B cell receptor (BCR) signals together with a multi-component co-receptor complex to initiate B cell activation in response to antigen binding. Here, we take advantage of peroxidase-catalyzed proximity labeling combined with quantitative mass spectrometry to track co-receptor signaling dynamics in Raji cells from 10 s to 2 h after BCR stimulation. This approach enables tracking of 2,814 proximity-labeled proteins and 1,394 phosphosites and provides an unbiased and quantitative molecular map of proteins recruited to the vicinity of CD19, the signaling subunit of the co-receptor complex. We detail the recruitment kinetics of signaling effectors to CD19 and identify previously uncharacterized mediators of B cell activation. We show that the glutamate transporter SLC1A1 is responsible for mediating rapid metabolic reprogramming and for maintaining redox homeostasis during B cell activation. This study provides a comprehensive map of BCR signaling and a rich resource for uncovering the complex signaling networks that regulate activation.
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Affiliation(s)
- Katherine J Susa
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
| | - Gary A Bradshaw
- Department of Systems Biology, Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Robyn J Eisert
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Charlotte M Schilling
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Marian Kalocsay
- Department of Experimental Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| | - Stephen C Blacklow
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA 02215, USA.
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
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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. 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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3
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Bedi A, Choi K, Keane C, Bolger-Munro M, Ambrose AR, Gold MR. WAVE2 Regulates Actin-Dependent Processes Induced by the B Cell Antigen Receptor and Integrins. Cells 2023; 12:2704. [PMID: 38067132 PMCID: PMC10705906 DOI: 10.3390/cells12232704] [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] [Received: 10/20/2023] [Revised: 11/22/2023] [Accepted: 11/22/2023] [Indexed: 12/18/2023] Open
Abstract
B cell antigen receptor (BCR) signaling induces actin cytoskeleton remodeling by stimulating actin severing, actin polymerization, and the nucleation of branched actin networks via the Arp2/3 complex. This enables B cells to spread on antigen-bearing surfaces in order to increase antigen encounters and to form an immune synapse (IS) when interacting with antigen-presenting cells (APCs). Although the WASp, N-WASp, and WAVE nucleation-promoting factors activate the Arp2/3 complex, the role of WAVE2 in B cells has not been directly assessed. We now show that both WAVE2 and the Arp2/3 complex localize to the peripheral ring of branched F-actin when B cells spread on immobilized anti-Ig antibodies. The siRNA-mediated depletion of WAVE2 reduced and delayed B cell spreading on immobilized anti-Ig, and this was associated with a thinner peripheral F-actin ring and reduced actin retrograde flow compared to control cells. Depleting WAVE2 also impaired integrin-mediated B cell spreading on fibronectin and the LFA-1-induced formation of actomyosin arcs. Actin retrograde flow amplifies BCR signaling at the IS, and we found that depleting WAVE2 reduced microcluster-based BCR signaling and signal amplification at the IS, as well as B cell activation in response to antigen-bearing cells. Hence, WAVE2 contributes to multiple actin-dependent processes in B lymphocytes.
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Affiliation(s)
- Abhishek Bedi
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Kate Choi
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Connor Keane
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Madison Bolger-Munro
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Ashley R Ambrose
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Michael R Gold
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
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4
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Carrasco YR. Building the synapse engine to drive B lymphocyte function. Immunol Lett 2023; 260:S0165-2478(23)00112-8. [PMID: 37369313 DOI: 10.1016/j.imlet.2023.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 06/05/2023] [Accepted: 06/22/2023] [Indexed: 06/29/2023]
Abstract
B cell receptor (BCR)-mediated antigen-specific recognition activates B lymphocytes and drives the humoral immune response. This enables the generation of antibody-producing plasma cells, the effector arm of the B cell immune response, and of memory B cells, which confer protection against additional encounters with antigen. B cells search for cognate antigen in the complex cellular microarchitecture of secondary lymphoid organs, where antigens are captured and exposed on the surface of different immune cells. While scanning the cell network, the BCR can be stimulated by a specific antigen and elicit the establishment of the immune synapse with the antigen-presenting cell. At the immune synapse, an integrin-enriched supramolecular domain is assembled at the periphery of the B cell contact with the antigen-presenting cell, ensuring a stable and long-lasting interaction. The coordinated action of the actomyosin cytoskeleton and the microtubule network in the inner B cell space provides a structural framework that integrates signaling events and antigen uptake through the generation of traction forces and organelle polarization. Accordingly, the B cell immune synapse can be envisioned as a temporal engine that drives the molecular mechanisms needed for successful B cell activation. Here, I review different aspects of the B cell synapse engine and provide insights into other aspects poorly known or virtually unexplored.
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Affiliation(s)
- Yolanda R Carrasco
- B Lymphocyte Dynamics Group, Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, 28049, Spain.
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5
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Eyre TA, Riches JC. The Evolution of Therapies Targeting Bruton Tyrosine Kinase for the Treatment of Chronic Lymphocytic Leukaemia: Future Perspectives. Cancers (Basel) 2023; 15:2596. [PMID: 37174062 PMCID: PMC10177608 DOI: 10.3390/cancers15092596] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/28/2023] [Accepted: 04/29/2023] [Indexed: 05/15/2023] Open
Abstract
The development of inhibitors of Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 (BCL2) has resulted in a paradigm shift in the treatment of chronic lymphocytic leukaemia (CLL) over the last decade. Observations regarding the importance of B-cell receptor signalling for the survival and proliferation of CLL cells led to the development of the first-in-class BTK inhibitor (BTKi), ibrutinib, for the treatment of CLL. Despite being better tolerated than chemoimmunotherapy, ibrutinib does have side effects, some of which are due to the off-target inhibition of kinases other than BTK. As a result, more specific inhibitors of BTK were developed, such as acalabrutinib and zanubrutinib, which have demonstrated equivalent/enhanced efficacy and improved tolerability in large randomized clinical trials. Despite the increased specificity for BTK, side effects and treatment resistance remain therapeutic challenges. As these drugs all bind covalently to BTK, an alternative approach was to develop noncovalent inhibitors of BTK, including pirtobrutinib and nemtabrutinib. The alternative mechanisms of BTK-binding of these agents has the potential to overcome resistance mutations, something that has been borne out in early clinical trial data. A further step in the clinical development of BTK inhibition has been the introduction of BTK degraders, which remove BTK by ubiquitination and proteasomal degradation, in marked contrast to BTK inhibition. This article will review the evolution of BTK inhibition for CLL and offer future perspectives on the sequencing of an increasing number of different agents, and how this may be impacted on by mutations in BTK itself and other kinases.
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Affiliation(s)
- Toby A. Eyre
- Oxford Cancer and Haematology Centre, Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, Headington, Oxford OX3 7LE, UK
| | - John C. Riches
- Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, London EC1M 6BQ, UK
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6
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Susa KJ, Bradshaw GA, Eisert RJ, Schilling CM, Kalocsay M, Blacklow SC, Kruse AC. A Spatiotemporal Map of Co-Receptor Signaling Networks Underlying B Cell Activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.17.533227. [PMID: 36993395 PMCID: PMC10055206 DOI: 10.1101/2023.03.17.533227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
The B cell receptor (BCR) signals together with a multi-component co-receptor complex to initiate B cell activation in response to antigen binding. This process underlies nearly every aspect of proper B cell function. Here, we take advantage of peroxidase-catalyzed proximity labeling combined with quantitative mass spectrometry to track B cell co-receptor signaling dynamics from 10 seconds to 2 hours after BCR stimulation. This approach enables tracking of 2,814 proximity-labeled proteins and 1,394 quantified phosphosites and provides an unbiased and quantitative molecular map of proteins recruited to the vicinity of CD19, the key signaling subunit of the co-receptor complex. We detail the recruitment kinetics of essential signaling effectors to CD19 following activation, and then identify new mediators of B cell activation. In particular, we show that the glutamate transporter SLC1A1 is responsible for mediating rapid metabolic reprogramming immediately downstream of BCR stimulation and for maintaining redox homeostasis during B cell activation. This study provides a comprehensive map of the BCR signaling pathway and a rich resource for uncovering the complex signaling networks that regulate B cell activation.
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Affiliation(s)
- Katherine J. Susa
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
- Current address: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - Gary A. Bradshaw
- Department of Systems Biology, Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Robyn J. Eisert
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Charlotte M. Schilling
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Marian Kalocsay
- Department of Experimental Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Stephen C. Blacklow
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
- Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA 02215, USA
| | - Andrew C. Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
- Lead contact
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7
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Lagos J, Sagadiev S, Diaz J, Bozo JP, Guzman F, Stefani C, Zanlungo S, Acharya M, Yuseff MI. Autophagy Induced by Toll-like Receptor Ligands Regulates Antigen Extraction and Presentation by B Cells. Cells 2022; 11:cells11233883. [PMID: 36497137 PMCID: PMC9741325 DOI: 10.3390/cells11233883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 12/05/2022] Open
Abstract
The engagement of B cells with surface-tethered antigens triggers the formation of an immune synapse (IS), where the local secretion of lysosomes can facilitate antigen uptake. Lysosomes intersect with other intracellular processes, such as Toll-like Receptor (TLR) signaling and autophagy coordinating immune responses. However, the crosstalk between these processes and antigen presentation remains unclear. Here, we show that TLR stimulation induces autophagy in B cells and decreases their capacity to extract and present immobilized antigens. We reveal that TLR stimulation restricts lysosome repositioning to the IS by triggering autophagy-dependent degradation of GEF-H1, a Rho GTP exchange factor required for stable lysosome recruitment at the synaptic membrane. GEF-H1 degradation is not observed in B cells that lack αV integrins and are deficient in TLR-induced autophagy. Accordingly, these cells show efficient antigen extraction in the presence of TLR stimulation, confirming the role of TLR-induced autophagy in limiting antigen extraction. Overall, our results suggest that resources associated with autophagy regulate TLR and BCR-dependent functions, which can finetune antigen uptake by B cells. This work helps to understand the mechanisms by which B cells are activated by surface-tethered antigens in contexts of subjacent inflammation before antigen recognition, such as sepsis.
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Affiliation(s)
- Jonathan Lagos
- Laboratory of Immune Cell Biology, Department of Cellular and Molecular Biology, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
- Center of Immunology and Immunotherapies, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Sara Sagadiev
- Center of Immunology and Immunotherapies, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Jheimmy Diaz
- Laboratory of Immune Cell Biology, Department of Cellular and Molecular Biology, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Juan Pablo Bozo
- Laboratory of Immune Cell Biology, Department of Cellular and Molecular Biology, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Fanny Guzman
- Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso 2373223, Chile
| | - Caroline Stefani
- Benaroya Research Institute at Virginia Mason, Seattle, WA 98101, USA
| | - Silvana Zanlungo
- Department of Gastroenterology, School of Medicine Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Mridu Acharya
- Center of Immunology and Immunotherapies, Seattle Children’s Research Institute, Seattle, WA 98101, USA
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Maria Isabel Yuseff
- Laboratory of Immune Cell Biology, Department of Cellular and Molecular Biology, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
- Correspondence:
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8
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Ton Tran HT, Li C, Chakraberty R, Cairo CW. NEU1 and NEU3 enzymes alter CD22 organization on B cells. BIOPHYSICAL REPORTS 2022; 2:100064. [PMID: 36425332 PMCID: PMC9680808 DOI: 10.1016/j.bpr.2022.100064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/19/2022] [Indexed: 06/16/2023]
Abstract
The B cell membrane expresses sialic-acid-binding immunoglobulin-like lectins, also called Siglecs, that are important for modulating immune response. Siglecs have interactions with sialoglycoproteins found on the same membrane (cis-ligands) that result in homotypic and heterotypic receptor clusters. The regulation and organization of these clusters, and their effect on cell activation, is not clearly understood. We investigated the role of human neuraminidase enzymes NEU1 and NEU3 on the clustering of CD22 on B cells using confocal microscopy. We observed that native NEU1 and NEU3 activity influence the cluster size of CD22. Using single-particle tracking, we observed that NEU3 activity increased the lateral mobility of CD22, which was in contrast to the effect of exogenous bacterial NEU enzymes. Moreover, we show that native NEU1 and NEU3 activity influenced cellular Ca2+ levels, supporting a role for these enzymes in regulating B cell activation. Our results establish a role for native NEU activity in modulating CD22 organization and function on B cells.
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Affiliation(s)
- Hanh-Thuc Ton Tran
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Caishun Li
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
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9
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McShane AN, Malinova D. The Ins and Outs of Antigen Uptake in B cells. Front Immunol 2022; 13:892169. [PMID: 35572544 PMCID: PMC9097226 DOI: 10.3389/fimmu.2022.892169] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 11/13/2022] Open
Abstract
A review of our current knowledge of B cell antigen uptake mechanisms, the relevance of these processes to pathology, and outstanding questions in the field. Specific antigens induce B cell activation through the B cell receptor (BCR) which initiates downstream signaling and undergoes endocytosis. While extensive research has shed light on the signaling pathways in health and disease, the endocytic mechanisms remain largely uncharacterized. Given the importance of BCR-antigen internalization for antigen presentation in initiating adaptive immune responses and its role in autoimmunity and malignancy, understanding the molecular mechanisms represents critical, and largely untapped, potential therapeutics. In this review, we discuss recent advancements in our understanding of BCR endocytic mechanisms and the role of the actin cytoskeleton and post-translational modifications in regulating BCR uptake. We discuss dysregulated BCR endocytosis in the context of B cell malignancies and autoimmune disorders. Finally, we pose several outstanding mechanistic questions which will critically advance our understanding of the coordination between BCR endocytosis and B cell activation.
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Affiliation(s)
- Adam Nathan McShane
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Dessislava Malinova
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
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10
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Seeley-Fallen MK, Lazzaro M, Liu C, Li QZ, Upadhyaya A, Song W. Non-Muscle Myosin II Is Essential for the Negative Regulation of B-Cell Receptor Signaling and B-Cell Activation. Front Immunol 2022; 13:842605. [PMID: 35493485 PMCID: PMC9047714 DOI: 10.3389/fimmu.2022.842605] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/21/2022] [Indexed: 11/30/2022] Open
Abstract
Antigen (Ag)-triggered B-cell receptor (BCR) signaling initiates antibody responses. However, prolonged or uncontrolled BCR signaling is associated with the development of self-reactive B-cells and autoimmune diseases. We previously showed that actin-mediated B-cell contraction on Ag-presenting surfaces negatively regulates BCR signaling. Non-muscle myosin II (NMII), an actin motor, is involved in B-cell development and antibody responses by mediating B-cell migration, cytokinesis, and Ag extraction from Ag-presenting cells. However, whether and how NMII regulates humoral responses through BCR signaling remains elusive. Utilizing a B-cell-specific, partial NMIIA knockout (cIIAKO) mouse model and NMII inhibitors, this study examined the role of NMII in BCR signaling. Upon BCR binding to antibody-coated planar lipid bilayers (PLB), NMIIA was recruited to the B-cell contact membrane and formed a ring-like structure during B-cell contraction. NMII recruitment depended on phosphatidylinositol 5-phosphatase (SHIP1), an inhibitory signaling molecule. NMII inhibition by cIIAKO did not affect B-cell spreading on PLB but delayed B-cell contraction and altered BCR clustering. Surface BCR “cap” formation induced by soluble stimulation was enhanced in cIIAKO B-cells. Notably, NMII inhibition by cIIAKO and inhibitors up-regulated BCR signaling in response to both surface-associated and soluble stimulation, increasing phosphorylated tyrosine, CD79a, BLNK, and Erk and decreasing phosphorylated SHIP1. While cIIAKO did not affect B-cell development, the number of germinal center B-cells was significantly increased in unimmunized cIIAKO mice, compared to control mice. While cIIAKO mice mounted similar antibody responses when compared to control mice upon immunization, the percentages of high-affinity antibodies, Ag-specific germinal center B-cells and isotype switched B-cells were significantly lower in cIIAKO mice than in control mice. Furthermore, autoantibody levels were elevated in cIIAKO mice, compared to control mice. Collectively, our results reveal that NMII exerts a B-cell-intrinsic inhibition on BCR signaling by regulating B-cell membrane contraction and surface BCR clustering, which curtails the activation of non-specific and self-reactive B-cells.
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Affiliation(s)
- Margaret K. Seeley-Fallen
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Michelle Lazzaro
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Chaohong Liu
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Quan-Zhen Li
- Department of Immunology and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, MD, United States
| | - Wenxia Song
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States
- *Correspondence: Wenxia Song,
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11
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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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12
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Ulloa R, Corrales O, Cabrera-Reyes F, Jara-Wilde J, Saez JJ, Rivas C, Lagos J, Härtel S, Quiroga C, Yuseff MI, Diaz-Muñoz J. B Cells Adapt Their Nuclear Morphology to Organize the Immune Synapse and Facilitate Antigen Extraction. Front Immunol 2022; 12:801164. [PMID: 35222354 PMCID: PMC8863768 DOI: 10.3389/fimmu.2021.801164] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/24/2021] [Indexed: 11/25/2022] Open
Abstract
Upon interaction with immobilized antigens, B cells form an immune synapse where actin remodeling and re-positioning of the microtubule-organizing center (MTOC) together with lysosomes can facilitate antigen extraction. B cells have restricted cytoplasmic space, mainly occupied by a large nucleus, yet the role of nuclear morphology in the formation of the immune synapse has not been addressed. Here we show that upon activation, B cells re-orientate and adapt the size of their nuclear groove facing the immune synapse, where the MTOC sits, and lysosomes accumulate. Silencing the nuclear envelope proteins Nesprin-1 and Sun-1 impairs nuclear reorientation towards the synapse and leads to defects in actin organization. Consequently, B cells are unable to internalize the BCR after antigen activation. Nesprin-1 and Sun-1-silenced B cells also fail to accumulate the tethering factor Exo70 at the center of the synaptic membrane and display defective lysosome positioning, impairing efficient antigen extraction at the immune synapse. Thus, changes in nuclear morphology and positioning emerge as critical regulatory steps to coordinate B cell activation.
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Affiliation(s)
- Romina Ulloa
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Oreste Corrales
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernanda Cabrera-Reyes
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge Jara-Wilde
- Laboratory for Scientific Image Analysis SCIAN-Lab, Programa de Biología Integrativa, Instituto de Ciencias Biomédicas ICBM, Facultad de Medicina, Universidad de Chile and Biomedical Neuroscience Institute BNI, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Juan José Saez
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Christopher Rivas
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jonathan Lagos
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Steffen Härtel
- Laboratory for Scientific Image Analysis SCIAN-Lab, Programa de Biología Integrativa, Instituto de Ciencias Biomédicas ICBM, Facultad de Medicina, Universidad de Chile and Biomedical Neuroscience Institute BNI, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Centro de Informática Médica y Telemedicina CIMT, Facultad de Medicina, Universidad de Chile and Centro Nacional en Sistemas de Información en Salud CENS, Santiago, Chile
| | - Clara Quiroga
- División de Enfermedades Cardiovasculares, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Universidad de Chile and 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
| | - Jheimmy Diaz-Muñoz
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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13
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Stage-Specific Non-Coding RNA Expression Patterns during In Vitro Human B Cell Differentiation into Antibody Secreting Plasma Cells. Noncoding RNA 2022; 8:ncrna8010015. [PMID: 35202088 PMCID: PMC8878715 DOI: 10.3390/ncrna8010015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/31/2022] [Accepted: 02/03/2022] [Indexed: 11/17/2022] Open
Abstract
The differentiation of B cells into antibody secreting plasma cells (PCs) is governed by a strict regulatory network that results in expression of specific transcriptomes along the activation continuum. In vitro models yielding significant numbers of PCs phenotypically identical to the in vivo state enable investigation of pathways, metabolomes, and non-coding (ncRNAs) not previously identified. The objective of our study was to characterize ncRNA expression during human B cell activation and differentiation. To achieve this, we used an in vitro system and performed RNA-seq on resting and activated B cells and PCs. Characterization of coding gene transcripts, including immunoglobulin (Ig), validated our system and also demonstrated that memory B cells preferentially differentiated into PCs. Importantly, we identified more than 980 ncRNA transcripts that are differentially expressed across the stages of activation and differentiation, some of which are known to target transcription, proliferation, cytoskeletal, autophagy and proteasome pathways. Interestingly, ncRNAs located within Ig loci may be targeting both Ig and non-Ig-related transcripts. ncRNAs associated with B cell malignancies were also identified. Taken together, this system provides a platform to study the role of specific ncRNAs in B cell differentiation and altered expression of those ncRNAs involved in B cell malignancies.
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14
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Holms RD, Ataullakhanov RI. Ezrin Peptide Therapy from HIV to COVID: Inhibition of Inflammation and Amplification of Adaptive Anti-Viral Immunity. Int J Mol Sci 2021; 22:11688. [PMID: 34769119 PMCID: PMC8584018 DOI: 10.3390/ijms222111688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/19/2021] [Accepted: 10/25/2021] [Indexed: 11/30/2022] Open
Abstract
Human Ezrin Peptides (HEPs) are inhibitors of expression of IL-6 and other inflammatory cytokines, amplifiers of adaptive B cell and T cell immunity and enhancers of tissue repair. The mutation stable C-terminus of HIV gp120, mimics 69% of the "Hep-receptor", a zipped α-helical structure in the middle of the α domain of human ezrin protein. Synthetic peptides homologous to the Hep-receptor of ezrin of five to fourteen amino acids, activate anti-viral immunity against a wide range of viruses (HIV, HCV, herpes, HPV, influenza and other human respiratory viruses). Human Ezrin Peptide One (HEP1) TEKKRRETVEREKE (brand name Gepon, registered for human use in Russia from 2001) is a successful treatment for opportunistic infections in HIV-infected patients. That treats HEP1and prevents mucosal candidiasis, herpes zoster outbreaks and infection-induced chronic diarrhea. There are clinical publications in Russian on the successful treatments of chronic recurrent vaginal candidiasis, acute and chronic enterocolitis and dysbacteriosis, which are accompanied by normalization of the mucosal microbiome, and the decline or disappearance of inflammation. HEP1 is also an effective treatment and prevention for recurrent inflammation and ulceration in the stomach, duodenum and colon. HEP1 and RepG3 GEKKRRETVEREGG (a derivative of HEP1) have been used successfully as an inhaled spray peptide solution to treat a small number of human volunteers with mild-to-moderate COVID, resulting from SARS-CoV-2 infection, based on earlier successes in treating acute viral respiratory disease with inflammatory complications. Ezrin peptides seem to correct a dysregulation of innate immune responses to SARS-CoV-2. They are also adjuvants of B cell adaptive immunity and increase antibody titres, resulting in protection from lethal virus infection of mice. In a clinical study in Moscow, orally administered HEP1 was shown to enhance antibody-titres produced in response to hepatitis-B vaccination. These very preliminary but promising results with ezrin peptide treatment of COVID must be replicated in large-scale randomised placebo controlled clinical studies, to be verified.
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15
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Deretic N, Bolger-Munro M, Choi K, Abraham L, Gold MR. The Actin-Disassembly Protein Glia Maturation Factor γ Enhances Actin Remodeling and B Cell Antigen Receptor Signaling at the Immune Synapse. Front Cell Dev Biol 2021; 9:647063. [PMID: 34336818 PMCID: PMC8318000 DOI: 10.3389/fcell.2021.647063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Signaling by the B cell antigen receptor (BCR) initiates actin remodeling. The assembly of branched actin networks that are nucleated by the Arp2/3 complex exert outward force on the plasma membrane, allowing B cells to form membrane protrusions that can scan the surface of antigen-presenting cells (APCs). The resulting Arp2/3 complex-dependent actin retrograde flow promotes the centripetal movement and progressive coalescence of BCR microclusters, which amplifies BCR signaling. Glia maturation factor γ (GMFγ) is an actin disassembly-protein that releases Arp2/3 complex-nucleated actin filaments from actin networks. By doing so, GMFγ could either oppose the actions of the Arp2/3 complex or support Arp2/3 complex-nucleated actin polymerization by contributing to the recycling of actin monomers and Arp2/3 complexes. We now show that reducing the levels of GMFγ in human B cell lines via transfection with a specific siRNA impairs the ability of B cells to spread on antigen-coated surfaces, decreases the velocity of actin retrograde flow, diminishes the coalescence of BCR microclusters into a central cluster at the B cell-APC contact site, and decreases APC-induced BCR signaling. These effects of depleting GMFγ are similar to what occurs when the Arp2/3 complex is inhibited. This suggests that GMFγ cooperates with the Arp2/3 complex to support BCR-induced actin remodeling and amplify BCR signaling at the immune synapse.
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Affiliation(s)
- Nikola Deretic
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Madison Bolger-Munro
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Kate Choi
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Libin Abraham
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Michael R Gold
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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16
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Li Y, Bhanja A, Upadhyaya A, Zhao X, Song W. WASp Is Crucial for the Unique Architecture of the Immunological Synapse in Germinal Center B-Cells. Front Cell Dev Biol 2021; 9:646077. [PMID: 34195186 PMCID: PMC8236648 DOI: 10.3389/fcell.2021.646077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 05/17/2021] [Indexed: 12/12/2022] Open
Abstract
B-cells undergo somatic hypermutation and affinity maturation in germinal centers. Somatic hypermutated germinal center B-cells (GCBs) compete to engage with and capture antigens on follicular dendritic cells. Recent studies show that when encountering membrane antigens, GCBs generate actin-rich pod-like structures with B-cell receptor (BCR) microclusters to facilitate affinity discrimination. While deficiencies in actin regulators, including the Wiskott-Aldrich syndrome protein (WASp), cause B-cell affinity maturation defects, the mechanism by which actin regulates BCR signaling in GBCs is not fully understood. Using WASp knockout (WKO) mice that express Lifeact-GFP and live-cell total internal reflection fluorescence imaging, this study examined the role of WASp-mediated branched actin polymerization in the GCB immunological synapse. After rapid spreading on antigen-coated planar lipid bilayers, GCBs formed microclusters of phosphorylated BCRs and proximal signaling molecules at the center and the outer edge of the contact zone. The centralized signaling clusters localized at actin-rich GCB membrane protrusions. WKO reduced the centralized micro-signaling clusters by decreasing the number and stability of F-actin foci supporting GCB membrane protrusions. The actin structures that support the spreading membrane also appeared less frequently and regularly in WKO than in WT GCBs, which led to reductions in both the level and rate of GCB spreading and antigen gathering. Our results reveal essential roles for WASp in the generation and maintenance of unique structures for GCB immunological synapses.
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Affiliation(s)
- Yanan Li
- Department of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China.,Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Child Infection and Immunity, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, National Clinical Research Center for Child Health and Disorders, Chongqing, China.,Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, College Park, MD, United States
| | - Anshuman Bhanja
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, College Park, MD, United States
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, College Park, MD, United States.,Institute for Physical Science and Technology, University of Maryland, College Park, College Park, MD, United States
| | - Xiaodong Zhao
- Department of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China.,Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Child Infection and Immunity, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, National Clinical Research Center for Child Health and Disorders, Chongqing, China
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, College Park, MD, United States
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17
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Bolger-Munro M, Choi K, Cheung F, Liu YT, Dang-Lawson M, Deretic N, Keane C, Gold MR. The Wdr1-LIMK-Cofilin Axis Controls B Cell Antigen Receptor-Induced Actin Remodeling and Signaling at the Immune Synapse. Front Cell Dev Biol 2021; 9:649433. [PMID: 33928084 PMCID: PMC8076898 DOI: 10.3389/fcell.2021.649433] [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: 01/04/2021] [Accepted: 03/12/2021] [Indexed: 12/27/2022] Open
Abstract
When B cells encounter membrane-bound antigens, the formation and coalescence of B cell antigen receptor (BCR) microclusters amplifies BCR signaling. The ability of B cells to probe the surface of antigen-presenting cells (APCs) and respond to APC-bound antigens requires remodeling of the actin cytoskeleton. Initial BCR signaling stimulates actin-related protein (Arp) 2/3 complex-dependent actin polymerization, which drives B cell spreading as well as the centripetal movement and coalescence of BCR microclusters at the B cell-APC synapse. Sustained actin polymerization depends on concomitant actin filament depolymerization, which enables the recycling of actin monomers and Arp2/3 complexes. Cofilin-mediated severing of actin filaments is a rate-limiting step in the morphological changes that occur during immune synapse formation. Hence, regulators of cofilin activity such as WD repeat-containing protein 1 (Wdr1), LIM domain kinase (LIMK), and coactosin-like 1 (Cotl1) may also be essential for actin-dependent processes in B cells. Wdr1 enhances cofilin-mediated actin disassembly. Conversely, Cotl1 competes with cofilin for binding to actin and LIMK phosphorylates cofilin and prevents it from binding to actin filaments. We now show that Wdr1 and LIMK have distinct roles in BCR-induced assembly of the peripheral actin structures that drive B cell spreading, and that cofilin, Wdr1, and LIMK all contribute to the actin-dependent amplification of BCR signaling at the immune synapse. Depleting Cotl1 had no effect on these processes. Thus, the Wdr1-LIMK-cofilin axis is critical for BCR-induced actin remodeling and for B cell responses to APC-bound antigens.
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Affiliation(s)
- Madison Bolger-Munro
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Kate Choi
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Faith Cheung
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Yi Tian Liu
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - May Dang-Lawson
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Nikola Deretic
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Connor Keane
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Michael R Gold
- Department of Microbiology & Immunology and Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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18
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Interplay between HGAL and Grb2 proteins regulates B-cell receptor signaling. Blood Adv 2020; 3:2286-2297. [PMID: 31362927 DOI: 10.1182/bloodadvances.2018016162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 05/30/2019] [Indexed: 01/30/2023] Open
Abstract
Human germinal center (GC)-associated lymphoma (HGAL) is an adaptor protein expressed in GC B cells. HGAL regulates cell motility and B-cell receptor (BCR) signaling, processes that are central for the successful completion of the GC reaction. Herein, we demonstrate phosphorylation of HGAL by Syk and Lyn kinases at tyrosines Y80, Y86, Y106Y107, Y128, and Y148. The HGAL YEN motif (amino acids 107-109) is similar to the phosphopeptide motif pYXN used as a binding site to the growth factor receptor-bound protein 2 (Grb2). We demonstrate by biochemical and molecular methodologies that HGAL directly interacts with Grb2. Concordantly, microscopy studies demonstrate HGAL-Grb2 colocalization in the membrane central supramolecular activation clusters (cSMAC) following BCR activation. Mutation of the HGAL putative binding site to Grb2 abrogates the interaction between these proteins. Further, this HGAL mutant localizes exclusively in the peripheral SMAC and decreases the rate and intensity of BCR accumulation in the cSMAC. Furthermore, we demonstrate that Grb2, HGAL, and Syk interact in the same complex, but Grb2 does not modulate the effects of HGAL on Syk kinase activity. Overall, the interplay between the HGAL and Grb2 regulates the magnitude of BCR signaling and synapse formation.
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19
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Pournia F, Dang-Lawson M, Choi K, Mo V, Lampe PD, Matsuuchi L. Identification of serine residues in the connexin43 carboxyl tail important for BCR-mediated spreading of B-lymphocytes. J Cell Sci 2020; 133:jcs237925. [PMID: 31964709 PMCID: PMC10682646 DOI: 10.1242/jcs.237925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/20/2019] [Indexed: 11/20/2022] Open
Abstract
B-lymphocytes recognize antigen via B-cell antigen receptors (BCRs). This binding induces signaling, leading to B-cell activation, proliferation and differentiation. Early events of BCR signaling include reorganization of actin and membrane spreading, which facilitates increased antigen gathering. We have previously shown that the gap junction protein connexin43 (Cx43; also known as GJA1) is phosphorylated upon BCR signaling, and its carboxyl tail (CT) is important for BCR-mediated spreading. Here, specific serine residues in the Cx43 CT that are phosphorylated following BCR stimulation were identified. A chimeric protein containing the extracellular and transmembrane domains of CD8 fused to the Cx43 CT was sufficient to support cell spreading. Cx43 CT truncations showed that the region between amino acids 246-307 is necessary for B-cell spreading. Site-specific serine-to-alanine mutations (S255A, S262A, S279A and S282A) resulted in differential effects on both BCR signaling and BCR-mediated spreading. These serine residues can serve as potential binding sites for actin remodeling mediators and/or BCR signaling effectors; therefore, our results may reflect unique roles for each of these serines in terms of linking the Cx43 CT to actin remodeling.
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Affiliation(s)
- Farnaz Pournia
- Cell and Developmental Biology Graduate Program, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
- Department of Zoology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - May Dang-Lawson
- Department of Zoology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Kate Choi
- Cell and Developmental Biology Graduate Program, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
- Department of Zoology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Victor Mo
- Cell and Developmental Biology Graduate Program, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
- Department of Zoology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Paul D Lampe
- Translational Research Program, Public Health Sciences and Human Biology Divisions, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N, Seattle, WA 98109-1024, USA
| | - Linda Matsuuchi
- Cell and Developmental Biology Graduate Program, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
- Department of Zoology, Life Sciences Institute, University of British Columbia (UBC), 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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20
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The role of actin and myosin in antigen extraction by B lymphocytes. Semin Cell Dev Biol 2019; 102:90-104. [PMID: 31862219 DOI: 10.1016/j.semcdb.2019.10.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/14/2019] [Accepted: 10/31/2019] [Indexed: 12/14/2022]
Abstract
B cells must extract antigens attached to the surface of antigen presenting cells to generate high-affinity antibodies. Antigen extraction requires force, and recent studies have implicated actomyosin-dependent pulling forces generated within the B cell as the major driver of antigen extraction. These actomyosin-dependent pulling forces also serve to test the affinity of the B cell antigen receptor for antigen prior to antigen extraction. Such affinity discrimination is central to the process of antibody affinity maturation. Here we review the evidence that actomyosin-dependent pulling forces generated within the B cell promote affinity discrimination and power antigen extraction. Our take on these critical B cell functions is influenced significantly by the recent identification of formin-generated, myosin-rich, concentric actin arcs in the medial portion of the T cell immune synapse, as B cells appear to contain a similar contractile actomyosin structure.
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21
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Galectin-8 Favors the Presentation of Surface-Tethered Antigens by Stabilizing the B Cell Immune Synapse. Cell Rep 2019; 25:3110-3122.e6. [PMID: 30540943 PMCID: PMC6302547 DOI: 10.1016/j.celrep.2018.11.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 10/03/2018] [Accepted: 11/13/2018] [Indexed: 11/21/2022] Open
Abstract
Complete activation of B cells relies on their capacity to extract tethered antigens from immune synapses by either exerting mechanical forces or promoting their proteolytic degradation through lysosome secretion. Whether antigen extraction can also be tuned by local cues originating from the lymphoid microenvironment has not been investigated. We here show that the expression of Galectin-8-a glycan-binding protein found in the extracellular milieu, which regulates interactions between cells and matrix proteins-is increased within lymph nodes under inflammatory conditions where it enhances B cell arrest phases upon antigen recognition in vivo and promotes synapse formation during BCR recognition of immobilized antigens. Galectin-8 triggers a faster recruitment and secretion of lysosomes toward the B cell-antigen contact site, resulting in efficient extraction of immobilized antigens through a proteolytic mechanism. Thus, extracellular cues can determine how B cells sense and extract tethered antigens and thereby tune B cell responses in vivo.
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22
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Sáez JJ, Diaz J, Ibañez J, Bozo JP, Cabrera Reyes F, Alamo M, Gobert FX, Obino D, Bono MR, Lennon-Duménil AM, Yeaman C, Yuseff MI. The exocyst controls lysosome secretion and antigen extraction at the immune synapse of B cells. J Cell Biol 2019; 218:2247-2264. [PMID: 31197029 PMCID: PMC6605794 DOI: 10.1083/jcb.201811131] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 04/11/2019] [Accepted: 05/22/2019] [Indexed: 02/06/2023] Open
Abstract
BCR engagement enhances microtubule stability, which triggers the mobilization of Exo70 from the centrosome to the immune synapse. BCR engagement activates GEF-H1, which promotes exocyst assembly required for the docking and secretion of lysosomes, facilitating the extraction of surface-tethered antigens. B lymphocytes capture antigens from the surface of presenting cells by forming an immune synapse. Local secretion of lysosomes, which are guided to the synaptic membrane by centrosome repositioning, can facilitate the extraction of immobilized antigens. However, the molecular basis underlying their delivery to precise domains of the plasma membrane remains elusive. Here we show that microtubule stabilization, triggered by engagement of the B cell receptor, acts as a cue to release centrosome-associated Exo70, which is redistributed to the immune synapse. This process is coupled to the recruitment and activation of GEF-H1, which is required for assembly of the exocyst complex, used to promote tethering and fusion of lysosomes at the immune synapse. B cells silenced for GEF-H1 or Exo70 display defective lysosome secretion, which results in impaired antigen extraction and presentation. Thus, centrosome repositioning coupled to changes in microtubule stability orchestrates the spatial-temporal distribution of the exocyst complex to promote polarized lysosome secretion at the immune synapse.
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Affiliation(s)
- Juan José Sáez
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.,Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Jheimmy Diaz
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge Ibañez
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Pablo Bozo
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernanda Cabrera Reyes
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Martina Alamo
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - François-Xavier Gobert
- INSERM U932, Institut Curie, Centre de Recherche, PSL Research University, Paris, Île-de-France, France
| | - Dorian Obino
- INSERM U932, Institut Curie, Centre de Recherche, PSL Research University, Paris, Île-de-France, France
| | - María Rosa Bono
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Ana-María Lennon-Duménil
- INSERM U932, Institut Curie, Centre de Recherche, PSL Research University, Paris, Île-de-France, France
| | - Charles Yeaman
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA
| | - María-Isabel Yuseff
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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23
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Bolger-Munro M, Choi K, Scurll JM, Abraham L, Chappell RS, Sheen D, Dang-Lawson M, Wu X, Priatel JJ, Coombs D, Hammer JA, Gold MR. Arp2/3 complex-driven spatial patterning of the BCR enhances immune synapse formation, BCR signaling and B cell activation. eLife 2019; 8:e44574. [PMID: 31157616 PMCID: PMC6591008 DOI: 10.7554/elife.44574] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 06/01/2019] [Indexed: 12/17/2022] Open
Abstract
When B cells encounter antigens on the surface of an antigen-presenting cell (APC), B cell receptors (BCRs) are gathered into microclusters that recruit signaling enzymes. These microclusters then move centripetally and coalesce into the central supramolecular activation cluster of an immune synapse. The mechanisms controlling BCR organization during immune synapse formation, and how this impacts BCR signaling, are not fully understood. We show that this coalescence of BCR microclusters depends on the actin-related protein 2/3 (Arp2/3) complex, which nucleates branched actin networks. Moreover, in murine B cells, this dynamic spatial reorganization of BCR microclusters amplifies proximal BCR signaling reactions and enhances the ability of membrane-associated antigens to induce transcriptional responses and proliferation. Our finding that Arp2/3 complex activity is important for B cell responses to spatially restricted membrane-bound antigens, but not for soluble antigens, highlights a critical role for Arp2/3 complex-dependent actin remodeling in B cell responses to APC-bound antigens.
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Affiliation(s)
- Madison Bolger-Munro
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverCanada
- Life Sciences Institute, I3 Research GroupUniversity of British ColumbiaVancouverCanada
| | - Kate Choi
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverCanada
- Life Sciences Institute, I3 Research GroupUniversity of British ColumbiaVancouverCanada
| | - Joshua M Scurll
- Department of Mathematics, Institute of Applied MathematicsUniversity of British ColumbiaVancouverCanada
| | - Libin Abraham
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverCanada
- Life Sciences Institute, I3 Research GroupUniversity of British ColumbiaVancouverCanada
- Department of Mathematics, Institute of Applied MathematicsUniversity of British ColumbiaVancouverCanada
| | - Rhys S Chappell
- Department of Mathematics, Institute of Applied MathematicsUniversity of British ColumbiaVancouverCanada
| | - Duke Sheen
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverCanada
- Life Sciences Institute, I3 Research GroupUniversity of British ColumbiaVancouverCanada
| | - May Dang-Lawson
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverCanada
- Life Sciences Institute, I3 Research GroupUniversity of British ColumbiaVancouverCanada
| | - Xufeng Wu
- Cell Biology and Physiology CenterNational Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - John J Priatel
- Department of Pathology and Laboratory MedicineUniversity of British ColumbiaVancouverCanada
- BC Children’s Hospital Research InstituteVancouverCanada
| | - Daniel Coombs
- Department of Mathematics, Institute of Applied MathematicsUniversity of British ColumbiaVancouverCanada
| | - John A Hammer
- Cell Biology and Physiology CenterNational Heart, Lung and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Michael R Gold
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverCanada
- Life Sciences Institute, I3 Research GroupUniversity of British ColumbiaVancouverCanada
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24
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Gold MR, Reth MG. Antigen Receptor Function in the Context of the Nanoscale Organization of the B Cell Membrane. Annu Rev Immunol 2019; 37:97-123. [DOI: 10.1146/annurev-immunol-042718-041704] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The B cell antigen receptor (BCR) plays a central role in the self/nonself selection of B lymphocytes and in their activation by cognate antigen during the clonal selection process. It was long thought that most cell surface receptors, including the BCR, were freely diffusing and randomly distributed. Since the advent of superresolution techniques, it has become clear that the plasma membrane is compartmentalized and highly organized at the nanometer scale. Hence, a complete understanding of the precise conformation and activation mechanism of the BCR must take into account the organization of the B cell plasma membrane. We review here the recent literature on the nanoscale organization of the lymphocyte membrane and discuss how this new information influences our view of the conformational changes that the BCR undergoes during activation.
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Affiliation(s)
- Michael R. Gold
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael G. Reth
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
- Department of Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, 79108 Freiburg, Germany
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25
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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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26
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Maity PC, Datta M, Nicolò A, Jumaa H. Isotype Specific Assembly of B Cell Antigen Receptors and Synergism With Chemokine Receptor CXCR4. Front Immunol 2019. [PMID: 30619343 DOI: 10.3389/fimmu.2018.02988.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Expression of the membrane-bound form of the immunoglobulin (Ig) as part of the antigen receptor is indispensable for both the development and the effector function of B cells. Among five known isotypes, IgM and IgD are the common B cell antigen receptors (BCRs) that are co-expressed in naïve B cells. Despite having identical antigen specificity and being associated with the same signaling heterodimer Igα/Igβ (CD79a/CD79b), IgM and IgD-BCR isotypes functionally differ from each other in the manner of antigen binding, the formation of isolated nanoclusters and in their interaction with co-receptors such as CD19 and CXCR4 on the plasma membrane. With recent developments in experimental techniques, it is now possible to investigate the nanoscale organization of the BCR and better understand early events of BCR engagement. Interestingly, the cytoskeleton network beneath the membrane controls the BCR isotype-specific organization and its interaction with co-receptors. BCR triggering results in reorganization of the cytoskeleton network, which is further modulated by isotype-specific signals from co-receptors. For instance, IgD-BCR is closely associated with CXCR4 on mature B cells and this close proximity allows CXCR4 to employ the BCR machinery as signaling hub. In this review, we discuss the functional specificity and nanocluster assembly of BCR isotypes and the consequences of cross-talk between CXCR4 and IgD-BCR. Furthermore, given the role of BCR and CXCR4 signaling in the development and survival of leukemic B cells, we discuss the consequences of the cross-talk between CXCR4 and the BCR for controlling the growth of transformed B cells.
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Affiliation(s)
| | - Moumita Datta
- Institute of Immunology, Ulm University, Ulm, Germany
| | | | - Hassan Jumaa
- Institute of Immunology, Ulm University, Ulm, Germany
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27
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Maity PC, Datta M, Nicolò A, Jumaa H. Isotype Specific Assembly of B Cell Antigen Receptors and Synergism With Chemokine Receptor CXCR4. Front Immunol 2019; 9:2988. [PMID: 30619343 PMCID: PMC6305424 DOI: 10.3389/fimmu.2018.02988] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 12/04/2018] [Indexed: 12/20/2022] Open
Abstract
Expression of the membrane-bound form of the immunoglobulin (Ig) as part of the antigen receptor is indispensable for both the development and the effector function of B cells. Among five known isotypes, IgM and IgD are the common B cell antigen receptors (BCRs) that are co-expressed in naïve B cells. Despite having identical antigen specificity and being associated with the same signaling heterodimer Igα/Igβ (CD79a/CD79b), IgM and IgD-BCR isotypes functionally differ from each other in the manner of antigen binding, the formation of isolated nanoclusters and in their interaction with co-receptors such as CD19 and CXCR4 on the plasma membrane. With recent developments in experimental techniques, it is now possible to investigate the nanoscale organization of the BCR and better understand early events of BCR engagement. Interestingly, the cytoskeleton network beneath the membrane controls the BCR isotype-specific organization and its interaction with co-receptors. BCR triggering results in reorganization of the cytoskeleton network, which is further modulated by isotype-specific signals from co-receptors. For instance, IgD-BCR is closely associated with CXCR4 on mature B cells and this close proximity allows CXCR4 to employ the BCR machinery as signaling hub. In this review, we discuss the functional specificity and nanocluster assembly of BCR isotypes and the consequences of cross-talk between CXCR4 and IgD-BCR. Furthermore, given the role of BCR and CXCR4 signaling in the development and survival of leukemic B cells, we discuss the consequences of the cross-talk between CXCR4 and the BCR for controlling the growth of transformed B cells.
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Affiliation(s)
| | - Moumita Datta
- Institute of Immunology, Ulm University, Ulm, Germany
| | | | - Hassan Jumaa
- Institute of Immunology, Ulm University, Ulm, Germany
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28
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Roman-Garcia S, Merino-Cortes SV, Gardeta SR, de Bruijn MJW, Hendriks RW, Carrasco YR. Distinct Roles for Bruton's Tyrosine Kinase in B Cell Immune Synapse Formation. Front Immunol 2018; 9:2027. [PMID: 30237801 PMCID: PMC6136277 DOI: 10.3389/fimmu.2018.02027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/17/2018] [Indexed: 12/11/2022] Open
Abstract
Bruton's tyrosine kinase (Btk) has a key role in the signaling pathways of receptors essential for the B lymphocyte response. Given its implication in B cell-related immunodeficiencies, leukemias/lymphomas and autoimmunity, Btk is studied intensely and is a target for therapy. Here, using primary B cells from distinct mouse models and the pharmacological inhibitors ibrutinib and acalabrutinib, we report distinct roles for Btk in antigen-triggered immune synapse (IS) formation. Btk recruitment to the plasma membrane regulates the B cell ability to trigger IS formation as well as its appropriate molecular assembly; Btk shuttling/scaffold activities seem more relevant than the kinase function on that. Btk-kinase activity controls antigen accumulation at the IS through the PLCγ2/Ca2+ axis. Impaired Btk membrane-recruitment or kinase function likewise alters antigen-triggered microtubule-organizing center (MTOC) polarization to the IS, B cell activation and proliferation. Data also show that, for B cell function, IS architecture is as important as the quantity of antigen that accumulates at the synapse.
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Affiliation(s)
- Sara Roman-Garcia
- B cell Dynamics Laboratory, Department on Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, Spain
| | - Sara V Merino-Cortes
- B cell Dynamics Laboratory, Department on Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, Spain
| | - Sofia R Gardeta
- B cell Dynamics Laboratory, Department on Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, Spain
| | | | - Rudi W Hendriks
- Department of Pulmonary Medicine, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Yolanda R Carrasco
- B cell Dynamics Laboratory, Department on Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, Spain
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29
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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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30
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Wang JC, Bolger-Munro M, Gold MR. Imaging the Interactions Between B Cells and Antigen-Presenting Cells. Methods Mol Biol 2018; 1707:131-161. [PMID: 29388105 DOI: 10.1007/978-1-4939-7474-0_10] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In vivo, B cells are often activated by antigens that are displayed on the surface of antigen-presenting cells (APCs). Binding of membrane-associated antigens to the B cell receptor (BCR) causes rapid cytoskeleton-dependent changes in the spatial organization of the BCR and other B cell membrane proteins, leading to the formation of an immune synapse. This process has been modeled using antigens attached to artificial planar lipid bilayers or to plasma membrane sheets. As a more physiological system for studying B cell-APC interactions, we have expressed model antigens in easily transfected adherent cell lines such as Cos-7 cells. The model antigens that we have used are a transmembrane form of a single-chain anti-Igκ antibody and a transmembrane form of hen egg lysozyme that is fused to a fluorescent protein. This has allowed us to study multiple aspects of B cell immune synapse formation including cytoskeletal reorganization, BCR microcluster coalescence, BCR-mediated antigen gathering, and BCR signaling. Here, we provide protocols for expressing these model antigens on the surface of Cos-7 cells, transfecting B cells with siRNAs or with plasmids encoding fluorescent proteins, using fixed cell and live cell fluorescence microscopy to image B cell-APC interactions, and quantifying APC-induced changes in BCR spatial organization and signaling.
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Affiliation(s)
- Jia C Wang
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Madison Bolger-Munro
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Michael R Gold
- Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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31
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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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32
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A Rough Energy Landscape to Describe Surface-Linked Antibody and Antigen Bond Formation. Sci Rep 2016; 6:35193. [PMID: 27731375 PMCID: PMC5059681 DOI: 10.1038/srep35193] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/27/2016] [Indexed: 11/08/2022] Open
Abstract
Antibodies and B cell receptors often bind their antigen at cell-cell interface while both molecular species are surface-bound, which impacts bond kinetics and function. Despite the description of complex energy landscapes for dissociation kinetics which may also result in significantly different association kinetics, surface-bound molecule (2D) association kinetics usually remain described by an on-rate due to crossing of a single free energy barrier, and few experimental works have measured association kinetics under conditions implying force and two-dimensional relative ligand-receptor motion. We use a new laminar flow chamber to measure 2D bond formation with systematic variation of the distribution of encounter durations between antigen and antibody, in a range from 0.1 to 10 ms. Under physiologically relevant forces, 2D association is 100-fold slower than 3D association as studied by surface plasmon resonance assays. Supported by brownian dynamics simulations, our results show that a minimal encounter duration is required for 2D association; an energy landscape featuring a rough initial part might be a reasonable way of accounting for this. By systematically varying the temperature of our experiments, we evaluate roughness at 2kBT, in the range of previously proposed rough parts of landscapes models during dissociation.
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33
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Abstract
An important underlying mechanism that contributes to autoimmunity is the loss of inhibitory signaling in the immune system. Sialic acid-recognizing Ig superfamily lectins or Siglecs are a family of cell surface proteins largely expressed in hematopoietic cells. The majority of Siglecs are inhibitory receptors expressed in immune cells that bind to sialic acid-containing ligands and recruit SH2-domain-containing tyrosine phosphatases to their cytoplasmic tails. They deliver inhibitory signals that can contribute to the constraining of immune cells, and thus protect the host from autoimmunity. The inhibitory functions of CD22/Siglec-2 and Siglec-G and their contributions to tolerance and autoimmunity, primarily in the B lymphocyte context, are considered in some detail in this review. The relevance to autoimmunity and unregulated inflammation of modified sialic acids, enzymes that modify sialic acid, and other sialic acid-binding proteins are also reviewed.
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Affiliation(s)
- Vinay S Mahajan
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.,Departments of Medicine and Pathology, Harvard Medical School, Boston, MA, USA.,Deaprtment of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Shiv Pillai
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.,Departments of Medicine and Pathology, Harvard Medical School, Boston, MA, USA
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34
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Label-free proteomic analysis of placental proteins during Toxoplasma gondii infection. J Proteomics 2016; 150:31-39. [PMID: 27569050 DOI: 10.1016/j.jprot.2016.08.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 08/15/2016] [Accepted: 08/23/2016] [Indexed: 12/24/2022]
Abstract
Toxoplasma gondii is a ubiquitous, obligate intracellular parasite capable of crossing the placental barrier and causing spontaneous abortion, preterm labor, or significant disease in the surviving neonate. To better understand molecular mechanisms underlying abnormal pregnancy outcomes caused by T. gondii, placental proteins extracted from T. gondii-infected and -uninfected mice were comparatively analyzed using label-free liquid chromatography-tandem mass spectrometry. Significant difference was observed in the expression of 58 out of 792 proteins in infected placentas (p<0.05) compared with that in uninfected placentas. Quantitative real-time polymerase chain reaction, western blotting, and immunohistochemical staining were used to validate the results of the proteomic analysis. Some placental proteins differentially expressed in infected and uninfected mice were found to be associated with several different biological processes of pregnancy, particularly with trophoblast invasion and placental development. The results provide possible novel insights into the molecular mechanisms for abnormal pregnancy outcomes associated with T. gondii infection. SIGNIFICANCE In order to further explore the mechanisms of abnormal pregnant outcomes caused by T. gondii infection, we first applied label-free proteomic technology to analyze the differentially expressed host placental proteins with T. gondii infection. The results showed that some differential proteins are associated with trophoblast invasion and placenta development. The findings provide a systemic view of the altered placental proteins and help to declare the molecular mechanisms of abnormal pregnancy outcomes caused by T. gondii infection.
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35
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Elucidation of tonic and activated B-cell receptor signaling in Burkitt's lymphoma provides insights into regulation of cell survival. Proc Natl Acad Sci U S A 2016; 113:5688-93. [PMID: 27155012 DOI: 10.1073/pnas.1601053113] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Burkitt's lymphoma (BL) is a highly proliferative B-cell neoplasm and is treated with intensive chemotherapy that, because of its toxicity, is often not suitable for the elderly or for patients with endemic BL in developing countries. BL cell survival relies on signals transduced by B-cell antigen receptors (BCRs). However, tonic as well as activated BCR signaling networks and their relevance for targeted therapies in BL remain elusive. We have systematically characterized and compared tonic and activated BCR signaling in BL by quantitative phosphoproteomics to identify novel BCR effectors and potential drug targets. We identified and quantified ∼16,000 phospho-sites in BL cells. Among these sites, 909 were related to tonic BCR signaling, whereas 984 phospho-sites were regulated upon BCR engagement. The majority of the identified BCR signaling effectors have not been described in the context of B cells or lymphomas yet. Most of these newly identified BCR effectors are predicted to be involved in the regulation of kinases, transcription, and cytoskeleton dynamics. Although tonic and activated BCR signaling shared a considerable number of effector proteins, we identified distinct phosphorylation events in tonic BCR signaling. We investigated the functional relevance of some newly identified BCR effectors and show that ACTN4 and ARFGEF2, which have been described as regulators of membrane-trafficking and cytoskeleton-related processes, respectively, are crucial for BL cell survival. Thus, this study provides a comprehensive dataset for tonic and activated BCR signaling and identifies effector proteins that may be relevant for BL cell survival and thus may help to develop new BL treatments.
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36
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Obino D, Farina F, Malbec O, Sáez PJ, Maurin M, Gaillard J, Dingli F, Loew D, Gautreau A, Yuseff MI, Blanchoin L, Théry M, Lennon-Duménil AM. Actin nucleation at the centrosome controls lymphocyte polarity. Nat Commun 2016; 7:10969. [PMID: 26987298 PMCID: PMC4802043 DOI: 10.1038/ncomms10969] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/05/2016] [Indexed: 01/01/2023] Open
Abstract
Cell polarity is required for the functional specialization of many cell types including lymphocytes. A hallmark of cell polarity is the reorientation of the centrosome that allows repositioning of organelles and vesicles in an asymmetric fashion. The mechanisms underlying centrosome polarization are not fully understood. Here we found that in resting lymphocytes, centrosome-associated Arp2/3 locally nucleates F-actin, which is needed for centrosome tethering to the nucleus via the LINC complex. Upon lymphocyte activation, Arp2/3 is partially depleted from the centrosome as a result of its recruitment to the immune synapse. This leads to a reduction in F-actin nucleation at the centrosome and thereby allows its detachment from the nucleus and polarization to the synapse. Therefore, F-actin nucleation at the centrosome—regulated by the availability of the Arp2/3 complex—determines its capacity to polarize in response to external stimuli. Cell polarity is marked by re-orientation of the centrosome, but the mechanisms governing centrosome polarization are poorly understood. Here Obino et al. show that in lymphocytes centrosome-associated Arp2/3 nucleates actin that tethers the centrosome to the nucleus; activation depletes Arp2/3 from the centrosome and frees it from the nucleus.
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Affiliation(s)
- Dorian Obino
- INSERM-U932 Immunité et Cancer, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
| | - Francesca Farina
- CytoMorpho Lab, Biosciences &Biotechnology Institute of Grenoble, UMR5168, CEA/INRA/CNRS/Université Grenoble-Alpes, Grenoble 38054, France
| | - Odile Malbec
- INSERM-U932 Immunité et Cancer, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
| | - Pablo J Sáez
- INSERM-U932 Immunité et Cancer, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
| | - Mathieu Maurin
- INSERM-U932 Immunité et Cancer, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
| | - Jérémie Gaillard
- CytoMorpho Lab, Biosciences &Biotechnology Institute of Grenoble, UMR5168, CEA/INRA/CNRS/Université Grenoble-Alpes, Grenoble 38054, France
| | - Florent Dingli
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
| | - Damarys Loew
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
| | | | - Maria-Isabel Yuseff
- Departamento de Biologia Celular y Molecular, Pontificia Universidad Catolica de Chile, Santiago 6513677, Chile
| | - Laurent Blanchoin
- CytoMorpho Lab, Biosciences &Biotechnology Institute of Grenoble, UMR5168, CEA/INRA/CNRS/Université Grenoble-Alpes, Grenoble 38054, France
| | - Manuel Théry
- CytoMorpho Lab, Biosciences &Biotechnology Institute of Grenoble, UMR5168, CEA/INRA/CNRS/Université Grenoble-Alpes, Grenoble 38054, France.,CytoMorpho Lab, Hopital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, CEA/INSERM/Université Paris Diderot, Paris 75010, France
| | - Ana-Maria Lennon-Duménil
- INSERM-U932 Immunité et Cancer, Institut Curie, PSL Research University, 75248 Paris Cedex 05, France
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Budzyńska PM, Niemelä M, Sarapulov AV, Kyläniemi MK, Nera KP, Junttila S, Laiho A, Mattila PK, Alinikula J, Lassila O. IRF4 Deficiency Leads to Altered BCR Signalling Revealed by Enhanced PI3K Pathway, Decreased SHIP Expression and Defected Cytoskeletal Responses. Scand J Immunol 2016; 82:418-28. [PMID: 26173778 DOI: 10.1111/sji.12343] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 07/07/2015] [Indexed: 12/13/2022]
Abstract
The graded expression of transcription factor interferon regulatory factor 4 (IRF4) regulates B cell development and is critical for plasma cell differentiation. However, the mechanisms, by which IRF4 elicits its crucial tasks, are largely unknown. To characterize the molecular targets of IRF4 in B cells, we established an IRF4-deficient DT40 B cell line. We found that in the absence of IRF4, the expression of several molecules involved in BCR signalling was altered. For example, the expression of B cell adaptor for PI3K (BCAP) was upregulated, whereas the SHIP (SH2-containing Inositol 5?-Phosphatase) expression was downregulated. These molecular unbalances were accompanied by increased BCR-induced calcium signalling, attenuated B cell linker protein (BLNK) and ERK activity and enhanced activity of PI3K/protein kinase B (Akt) pathway. Further, the IRF4-deficient cells showed dramatically diminished cytoskeletal responses to anti-IgM cross-linking. Our results show that IRF4 has an important role in the regulation of BCR signalling and help to shed light on the molecular mechanisms of B cell development and germinal centre response.
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Affiliation(s)
- P M Budzyńska
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.,Turku Doctoral Programme of Biomedical Sciences, University of Turku, Turku, Finland
| | - M Niemelä
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland
| | - A V Sarapulov
- Institute of Biomedicine, Department of Pathology, University of Turku, Turku, Finland
| | - M K Kyläniemi
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland
| | - K-P Nera
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland
| | - S Junttila
- The Finnish Microarray and Sequencing Center, Turku Centre for Biotechnology, Turku, Finland
| | - A Laiho
- The Finnish Microarray and Sequencing Center, Turku Centre for Biotechnology, Turku, Finland
| | - P K Mattila
- Institute of Biomedicine, Department of Pathology, University of Turku, Turku, Finland
| | - J Alinikula
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland
| | - O Lassila
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland
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38
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The cytoskeleton in cell-autonomous immunity: structural determinants of host defence. Nat Rev Immunol 2015; 15:559-73. [PMID: 26292640 DOI: 10.1038/nri3877] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Host cells use antimicrobial proteins, pathogen-restrictive compartmentalization and cell death in their defence against intracellular pathogens. Recent work has revealed that four components of the cytoskeleton--actin, microtubules, intermediate filaments and septins, which are well known for their roles in cell division, shape and movement--have important functions in innate immunity and cellular self-defence. Investigations using cellular and animal models have shown that these cytoskeletal proteins are crucial for sensing bacteria and for mobilizing effector mechanisms to eliminate them. In this Review, we highlight the emerging roles of the cytoskeleton as a structural determinant of cell-autonomous host defence.
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Abstract
The fate of T and B lymphocytes, the key cells that direct the adaptive immune response, is regulated by a diverse network of signal transduction pathways. The T- and B-cell antigen receptors are coupled to intracellular tyrosine kinases and adaptor molecules to control the metabolism of inositol phospholipids and calcium release. The production of inositol polyphosphates and lipid second messengers directs the activity of downstream guanine-nucleotide-binding proteins and protein and lipid kinases/phosphatases that control lymphocyte transcriptional and metabolic programs. Lymphocyte activation is modulated by costimulatory molecules and cytokines that elicit intracellular signaling that is integrated with the antigen-receptor-controlled pathways.
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Affiliation(s)
- Doreen Cantrell
- College of Life Sciences, Wellcome Trust Biocentre, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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40
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Kremlitzka M, Mácsik-Valent B, Erdei A. Syk is indispensable for CpG-induced activation and differentiation of human B cells. Cell Mol Life Sci 2015; 72:2223-36. [PMID: 25543269 PMCID: PMC11113211 DOI: 10.1007/s00018-014-1806-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 11/21/2014] [Accepted: 12/15/2014] [Indexed: 12/11/2022]
Abstract
B cells are efficiently activated by CpG oligodeoxynucleotides (ODNs) to produce pro-inflammatory cytokines and antibody (Ab). Here, we describe a so far unidentified, spleen tyrosine kinase (Syk)-dependent pathway, which is indispensable for CpG-induced human B cell activation. We show that triggering of B cells by CpG results in Syk and src kinase phosphorylation, proliferation, as well as cytokine and Ab production independent of the BCR. Notably, all these functions are abrogated when Syk is inhibited. We demonstrate that CpG-induced Syk activation originates from the cell surface in a TLR9-dependent manner. While inhibition of Syk does not influence the uptake of CpG ODNs, activation of the kinase is a prerequisite for the delivery of CpG into TLR9-containing endolysosomes and for the CpG-induced up-regulation of TLR9 expression. Our results reveal an alternative, Syk-dependent pathway of CpG-induced B cell stimulation, which is initiated at the plasma membrane and seems to be an upstream requirement for endosomal TLR9-driven B cell proliferation and differentiation.
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Affiliation(s)
| | - Bernadett Mácsik-Valent
- Department of Immunology, Eötvös Loránd University, 1117 Budapest Pázmány s. 1/c, Budapest, Hungary
| | - Anna Erdei
- Department of Immunology, Eötvös Loránd University, 1117 Budapest Pázmány s. 1/c, Budapest, Hungary
- MTA-ELTE Immunology Research Group, Budapest, Hungary
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41
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Quintero CA, Tudela JG, Damiani MT. Rho GTPases as pathogen targets: Focus on curable sexually transmitted infections. Small GTPases 2015; 6:108-18. [PMID: 26023809 DOI: 10.4161/21541248.2014.991233] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Pathogens have evolved highly specialized mechanisms to infect hosts. Several microorganisms modulate the eukaryotic cell surface to facilitate their engulfment. Once internalized, they hijack the molecular machinery of the infected cell for their own benefit. At different stages of phagocytosis, particularly during invasion, certain pathogens manipulate pathways governed by small GTPases. In this review, we focus on the role of Rho proteins on curable, sexually transmitted infections caused by Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and Treponema pallidum. Despite the high, worldwide frequencies of these sexually-transmitted diseases, very little is known about the strategies developed by these microorganisms to usurp key eukaryotic proteins that control intracellular signaling and actin dynamics. Improved knowledge of these molecular mechanisms will contribute to the elucidation of how these clinically important pathogens manipulate intracellular processes and parasitize their hosts.
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Affiliation(s)
- Cristián A Quintero
- a Laboratory of Phagocytosis and Intracellular Trafficking; IHEM-CONICET; School of Medicine; University of Cuyo ; Mendoza , Argentina
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42
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Freeman SA, Jaumouillé V, Choi K, Hsu BE, Wong HS, Abraham L, Graves ML, Coombs D, Roskelley CD, Das R, Grinstein S, Gold MR. Toll-like receptor ligands sensitize B-cell receptor signalling by reducing actin-dependent spatial confinement of the receptor. Nat Commun 2015; 6:6168. [PMID: 25644899 PMCID: PMC4327415 DOI: 10.1038/ncomms7168] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 12/22/2014] [Indexed: 01/26/2023] Open
Abstract
Integrating signals from multiple receptors allows cells to interpret the physiological context in which a signal is received. Here we describe a mechanism for receptor crosstalk in which receptor-induced increases in actin dynamics lower the threshold for signalling by another receptor. We show that the Toll-like receptor ligands lipopolysaccharide and CpG DNA, which are conserved microbial molecules, enhance signalling by the B-cell antigen receptor (BCR) by activating the actin-severing protein cofilin. Single-particle tracking reveals that increased severing of actin filaments reduces the spatial confinement of the BCR within the plasma membrane and increases BCR mobility. This allows more frequent collisions between BCRs and greater signalling in response to low densities of membrane-bound antigen. These findings implicate actin dynamics as a means of tuning receptor signalling and as a mechanism by which B cells distinguish inert antigens from those that are accompanied by indicators of microbial infection. Microbial pathogens can activate both innate and adaptive receptors, and integration of these signals may enhance the sensitivity of the immune response. Freeman et al. show that innate microbial cues sensitize B cells to antigen by increasing actin dynamics and reducing the actin-dependent confinement of the B-cell receptor.
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Affiliation(s)
- Spencer A Freeman
- 1] Department of Microbiology &Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Department of Cellular &Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [3] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [4] Program in Cell Biology, The Hospital for Sick Kids Research Institute, 686 Bay Street, Toronto, Ontario, Canada M5G 0A4
| | - Valentin Jaumouillé
- Program in Cell Biology, The Hospital for Sick Kids Research Institute, 686 Bay Street, Toronto, Ontario, Canada M5G 0A4
| | - Kate Choi
- 1] Department of Microbiology &Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Brian E Hsu
- 1] Department of Microbiology &Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Harikesh S Wong
- Program in Cell Biology, The Hospital for Sick Kids Research Institute, 686 Bay Street, Toronto, Ontario, Canada M5G 0A4
| | - Libin Abraham
- 1] Department of Microbiology &Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [3] Department of Mathematics and Institute of Applied Mathematics, 1984 Mathematics Road, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2
| | - Marcia L Graves
- 1] Department of Microbiology &Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Department of Cellular &Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [3] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Daniel Coombs
- Department of Mathematics and Institute of Applied Mathematics, 1984 Mathematics Road, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2
| | - Calvin D Roskelley
- 1] Department of Cellular &Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Raibatak Das
- Department of Integrative Biology, University of Colorado Denver, 1151 Arapahoe, Denver, Colorado 80204, USA
| | - Sergio Grinstein
- Program in Cell Biology, The Hospital for Sick Kids Research Institute, 686 Bay Street, Toronto, Ontario, Canada M5G 0A4
| | - Michael R Gold
- 1] Department of Microbiology &Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3 [2] Life Sciences Institute I3 and Cell Research Groups, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
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43
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Maity PC, Yang J, Klaesener K, Reth M. The nanoscale organization of the B lymphocyte membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:830-40. [PMID: 25450974 PMCID: PMC4547082 DOI: 10.1016/j.bbamcr.2014.11.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 10/30/2014] [Accepted: 11/07/2014] [Indexed: 12/13/2022]
Abstract
The fluid mosaic model of Singer and Nicolson correctly predicted that the plasma membrane (PM) forms a lipid bi-layer containing many integral trans-membrane proteins. This model also suggested that most of these proteins were randomly dispersed and freely diffusing moieties. Initially, this view of a dynamic and rather unorganized membrane was supported by early observations of the cell surfaces using the light microscope. However, recent studies on the PM below the diffraction limit of visible light (~250nm) revealed that, at nanoscale dimensions, membranes are highly organized and compartmentalized structures. Lymphocytes are particularly useful to study this nanoscale membrane organization because they grow as single cells and are not permanently engaged in cell:cell contacts within a tissue that can influence membrane organization. In this review, we describe the methods that can be used to better study the protein:protein interaction and nanoscale organization of lymphocyte membrane proteins, with a focus on the B cell antigen receptor (BCR). Furthermore, we discuss the factors that may generate and maintain these membrane structures.
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Affiliation(s)
- Palash Chandra Maity
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany; Department of Molecular Immunology, Biology III, University of Freiburg, Germany; Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
| | - Jianying Yang
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany; Department of Molecular Immunology, Biology III, University of Freiburg, Germany; Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Kathrin Klaesener
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany; Department of Molecular Immunology, Biology III, University of Freiburg, Germany; Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Michael Reth
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany; Department of Molecular Immunology, Biology III, University of Freiburg, Germany; Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
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44
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Ketchum C, Miller H, Song W, Upadhyaya A. Ligand mobility regulates B cell receptor clustering and signaling activation. Biophys J 2014; 106:26-36. [PMID: 24411234 DOI: 10.1016/j.bpj.2013.10.043] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/19/2013] [Accepted: 10/28/2013] [Indexed: 11/15/2022] Open
Abstract
Antigen binding to the B cell receptor (BCR) induces receptor clustering, cell spreading, and the formation of signaling microclusters, triggering B cell activation. Although the biochemical pathways governing early B cell signaling have been well studied, the role of the physical properties of antigens, such as antigen mobility, has not been fully examined. We study the interaction of B cells with BCR ligands coated on glass or tethered to planar lipid bilayer surfaces to investigate the differences in B cell response to immobile and mobile ligands. Using high-resolution total internal reflection fluorescence (TIRF) microscopy of live cells, we followed the movement and spatial organization of BCR clusters and the associated signaling. Although ligands on either surface were able to cross-link BCRs and induce clustering, B cells interacting with mobile ligands displayed greater signaling than those interacting with immobile ligands. Quantitative analysis revealed that mobile ligands enabled BCR clusters to move farther and merge more efficiently than immobile ligands. These differences in physical reorganization of receptor clusters were associated with differences in actin remodeling. Perturbation experiments revealed that a dynamic actin cytoskeleton actively reorganized receptor clusters. These results suggest that ligand mobility is an important parameter for regulating B cell signaling.
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Affiliation(s)
- Christina Ketchum
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742
| | - Heather Miller
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Wenxia Song
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Arpita Upadhyaya
- Biophysics Graduate 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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45
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Kläsener K, Maity PC, Hobeika E, Yang J, Reth M. B cell activation involves nanoscale receptor reorganizations and inside-out signaling by Syk. eLife 2014; 3:e02069. [PMID: 24963139 PMCID: PMC4067077 DOI: 10.7554/elife.02069] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Binding of antigen to the B cell antigen receptor (BCR) initiates a multitude of events resulting in B cell activation. How the BCR becomes signaling-competent upon antigen binding is still a matter of controversy. Using a high-resolution proximity ligation assay (PLA) to monitor the conformation of the BCR and its interactions with co-receptors at a 10-20 nm resolution, we provide direct evidence for the opening of BCR dimers during B cell activation. We also show that upon binding Syk opens the receptor by an inside-out signaling mechanism that amplifies BCR signaling. Furthermore, we found that on resting B cells, the coreceptor CD19 is in close proximity with the IgD-BCR and on activated B cells with the IgM-BCR, indicating nanoscale reorganization of receptor clusters during B cell activation.DOI: http://dx.doi.org/10.7554/eLife.02069.001.
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Affiliation(s)
- Kathrin Kläsener
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Max Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Palash C Maity
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Max Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Elias Hobeika
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Max Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Jianying Yang
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Max Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Michael Reth
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany Max Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
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46
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Actin-binding protein 1 links B-cell antigen receptors to negative signaling pathways. Proc Natl Acad Sci U S A 2014; 111:9881-6. [PMID: 24958882 DOI: 10.1073/pnas.1321971111] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Prolonged or uncontrolled B-cell receptor (BCR) signaling is associated with autoimmunity. We previously demonstrated a role for actin in BCR signal attenuation. This study reveals that actin-binding protein 1 (Abp1/HIP-55/SH3P7) is a negative regulator of BCR signaling and links actin to negative regulatory pathways of the BCR. In both Abp1(-/-) and bone marrow chimeric mice, in which only B cells lack Abp1 expression, the number of spontaneous germinal center and marginal zone B cells and the level of autoantibody are significantly increased. Serum levels of T-independent antibody responses and total antibody are elevated, whereas T-dependent antibody responses are markedly reduced and fail to undergo affinity maturation. Upon activation, surface BCR clustering is enhanced and B-cell contraction delayed in Abp1(-/-) B cells, concurrent with slow but persistent increases in F-actin at BCR signalosomes. Furthermore, BCR signaling is enhanced in Abp1(-/-) B cells compared with wild-type B cells, including Ca(2+) flux and phosphorylation of B-cell linker protein, the mitogen-activated protein kinase kinase MEK1/2, and ERK, coinciding with reductions in recruitment of the inhibitory signaling molecules hematopoietic progenitor kinase 1 and SH2-containing inositol 5-phosphatase to BCR signalosomes. Our results indicate that Abp1 negatively regulates BCR signaling by coupling actin remodeling to B-cell contraction and activation of inhibitory signaling molecules, which contributes to the regulation of peripheral B-cell development and antibody responses.
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47
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Song W, Liu C, Seeley-Fallen MK, Miller H, Ketchum C, Upadhyaya A. Actin-mediated feedback loops in B-cell receptor signaling. Immunol Rev 2014; 256:177-89. [PMID: 24117821 DOI: 10.1111/imr.12113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Upon recognizing cognate antigen, B cells mobilize multiple cellular apparatuses to propagate an optimal response. Antigen binding is transduced into cytoplasmic signaling events through B-cell antigen receptor (BCR)-based signalosomes at the B-cell surface. BCR signalosomes are dynamic and transient and are subsequently endocytosed for antigen processing. The function of BCR signalosomes is one of the determining factors for the fate of B cells: clonal expansion, anergy, or apoptosis. Accumulating evidence underscores the importance of the actin cytoskeleton in B-cell activation. We have begun to appreciate the role of actin dynamics in regulating BCR-mediated tonic signaling and the formation of BCR signalosomes. Our recent studies reveal an additional function of the actin cytoskeleton in the downregulation of BCR signaling, consequently contributing to the generation and maintenance of B-cell self-tolerance. In this review, we discuss how actin remodels its organization and dynamics in close coordination with BCR signaling and how actin remodeling in turn amplifies the activation and subsequent downregulation process of BCR signaling, providing vital feedback for optimal BCR activation.
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Affiliation(s)
- Wenxia Song
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, USA
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48
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Li XW, Rees JS, Xue P, Zhang H, Hamaia SW, Sanderson B, Funk PE, Farndale RW, Lilley KS, Perrett S, Jackson AP. New insights into the DT40 B cell receptor cluster using a proteomic proximity labeling assay. J Biol Chem 2014; 289:14434-47. [PMID: 24706754 PMCID: PMC4031500 DOI: 10.1074/jbc.m113.529578] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In the vertebrate immune system, each B-lymphocyte expresses a surface IgM-class B cell receptor (BCR). When cross-linked by antigen or anti-IgM antibody, the BCR accumulates with other proteins into distinct surface clusters that activate cell signaling, division, or apoptosis. However, the molecular composition of these clusters is not well defined. Here we describe a quantitative assay we call selective proteomic proximity labeling using tyramide (SPPLAT). It allows proteins in the immediate vicinity of a target to be selectively biotinylated, and hence isolated for mass spectrometry analysis. Using the chicken B cell line DT40 as a model, we use SPPLAT to provide the first proteomic analysis of any BCR cluster using proximity labeling. We detect known components of the BCR cluster, including integrins, together with proteins not previously thought to be BCR-associated. In particular, we identify the chicken B-lymphocyte allotypic marker chB6. We show that chB6 moves to within about 30–40 nm of the BCR following BCR cross-linking, and we show that cross-linking chB6 activates cell binding to integrin substrates laminin and gelatin. Our work provides new insights into the nature and composition of the BCR cluster, and confirms SPPLAT as a useful research tool in molecular and cellular proteomics.
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Affiliation(s)
- Xue-Wen Li
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, the University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Johanna S Rees
- the Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom, the Cambridge Centre for Proteomics, Tennis Court Road, University of Cambridge, Cambridge CB2 1QR, United Kingdom
| | - Peng Xue
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Hong Zhang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Samir W Hamaia
- the Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Bailey Sanderson
- the Department of Biological Sciences, DePaul University, Chicago, Illinois 60604, and
| | - Phillip E Funk
- the Department of Biological Sciences, DePaul University, Chicago, Illinois 60604, and
| | - Richard W Farndale
- the Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Kathryn S Lilley
- the Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom, the Cambridge Centre for Proteomics, Tennis Court Road, University of Cambridge, Cambridge CB2 1QR, United Kingdom
| | - Sarah Perrett
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China,
| | - Antony P Jackson
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China, the Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom,
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Liu C, Bai X, Wu J, Sharma S, Upadhyaya A, Dahlberg CIM, Westerberg LS, Snapper SB, Zhao X, Song W. N-wasp is essential for the negative regulation of B cell receptor signaling. PLoS Biol 2013; 11:e1001704. [PMID: 24223520 PMCID: PMC3818172 DOI: 10.1371/journal.pbio.1001704] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 09/25/2013] [Indexed: 11/19/2022] Open
Abstract
Negative regulation of receptor signaling is essential for controlling cell activation and differentiation. In B-lymphocytes, the down-regulation of B-cell antigen receptor (BCR) signaling is critical for suppressing the activation of self-reactive B cells; however, the mechanism underlying the negative regulation of signaling remains elusive. Using genetically manipulated mouse models and total internal reflection fluorescence microscopy, we demonstrate that neuronal Wiskott-Aldrich syndrome protein (N-WASP), which is coexpressed with WASP in all immune cells, is a critical negative regulator of B-cell signaling. B-cell-specific N-WASP gene deletion causes enhanced and prolonged BCR signaling and elevated levels of autoantibodies in the mouse serum. The increased signaling in N-WASP knockout B cells is concurrent with increased accumulation of F-actin at the B-cell surface, enhanced B-cell spreading on the antigen-presenting membrane, delayed B-cell contraction, inhibition in the merger of signaling active BCR microclusters into signaling inactive central clusters, and a blockage of BCR internalization. Upon BCR activation, WASP is activated first, followed by N-WASP in mouse and human primary B cells. The activation of N-WASP is suppressed by Bruton's tyrosine kinase-induced WASP activation, and is restored by the activation of SH2 domain-containing inositol 5-phosphatase that inhibits WASP activation. Our results reveal a new mechanism for the negative regulation of BCR signaling and broadly suggest an actin-mediated mechanism for signaling down-regulation.
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MESH Headings
- Actins/metabolism
- Animals
- Antibodies, Antinuclear/blood
- Antigens/immunology
- Autoantibodies/blood
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- Cells, Cultured
- Humans
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Knockout
- Protein Transport
- Receptors, Antigen, B-Cell/metabolism
- Signal Transduction
- Wiskott-Aldrich Syndrome/immunology
- Wiskott-Aldrich Syndrome/metabolism
- Wiskott-Aldrich Syndrome Protein/metabolism
- Wiskott-Aldrich Syndrome Protein, Neuronal/physiology
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Affiliation(s)
- Chaohong Liu
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Xiaoming Bai
- Division of Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Junfeng Wu
- Division of Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Shruti Sharma
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, Maryland, United States of America
| | - Carin I. M. Dahlberg
- Translational Immunology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden
| | - Lisa S. Westerberg
- Translational Immunology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden
| | - Scott B. Snapper
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Xiaodong Zhao
- Division of Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Wenxia Song
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
- Division of Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China
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