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Zhang T, Hu W, Chen W. Plasma Membrane Integrates Biophysical and Biochemical Regulation to Trigger Immune Receptor Functions. Front Immunol 2021; 12:613185. [PMID: 33679752 PMCID: PMC7933204 DOI: 10.3389/fimmu.2021.613185] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 01/06/2021] [Indexed: 11/23/2022] Open
Abstract
Plasma membrane provides a biophysical and biochemical platform for immune cells to trigger signaling cascades and immune responses against attacks from foreign pathogens or tumor cells. Mounting evidence suggests that the biophysical-chemical properties of this platform, including complex compositions of lipids and cholesterols, membrane tension, and electrical potential, could cooperatively regulate the immune receptor functions. However, the molecular mechanism is still unclear because of the tremendous compositional complexity and spatio-temporal dynamics of the plasma membrane. Here, we review the recent significant progress of dynamical regulation of plasma membrane on immune receptors, including T cell receptor, B cell receptor, Fc receptor, and other important immune receptors, to proceed mechano-chemical sensing and transmembrane signal transduction. We also discuss how biophysical-chemical cues couple together to dynamically tune the receptor's structural conformation or orientation, distribution, and organization, thereby possibly impacting their in-situ ligand binding and related signal transduction. Moreover, we propose that electrical potential could potentially induce the biophysical-chemical coupling change, such as lipid distribution and membrane tension, to inevitably regulate immune receptor activation.
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Affiliation(s)
- Tongtong Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The Center for Integrated Oncology and Precision Medicine, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Hu
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Chen
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory for Biomedical Engineering of Ministry of Education, State Key Laboratory for Modern Optical Instrumentation, College of Biomedical Engineering and Instrument Science, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
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2
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Lindner SE, Egelston CA, Huard SM, Lee PP, Wang LD. Arhgap25 Deficiency Leads to Decreased Numbers of Peripheral Blood B Cells and Defective Germinal Center Reactions. Immunohorizons 2020; 4:274-281. [PMID: 32434881 DOI: 10.4049/immunohorizons.2000021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 05/05/2020] [Indexed: 02/03/2023] Open
Abstract
Rho family GTPases are critical for normal B cell development and function, and their activity is regulated by a large and complex network of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). However, the role of GAPs in B cell development is poorly understood. In this study, we show that the novel Rac-GAP ARHGAP25 is important for B cell development in mice in a CXCR4-dependent manner. We show that Arhgap25 deficiency in mice leads to a significant decrease in peripheral blood B cell numbers as well as defects in mature B cell differentiation. Arhgap25-/- B cells respond to Ag stimulation in vitro and in vivo but have impaired germinal center formation and decreased IgG1 class switching. Additionally, Arhgap25-/- B cells show evidence of increased baseline motility and augmented chemotaxis to CXCL12. Taken together, these studies demonstrate an important role for Arhgap25 in peripheral B cell development and Ag response.
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Affiliation(s)
- Silke E Lindner
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010; and
| | - Colt A Egelston
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010; and
| | - Stephanie M Huard
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010; and
| | - Peter P Lee
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010; and
| | - Leo D Wang
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010; and .,Department of Pediatrics, City of Hope National Medical Center, Duarte, CA 91010
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3
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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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Del Valle Batalla F, Lennon-Dumenil AM, Yuseff MI. Tuning B cell responses to antigens by cell polarity and membrane trafficking. Mol Immunol 2018; 101:140-145. [PMID: 29935436 DOI: 10.1016/j.molimm.2018.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/01/2018] [Accepted: 06/09/2018] [Indexed: 01/01/2023]
Abstract
The capacity of B lymphocytes to produce specific antibodies, particularly broadly neutralizing antibodies that provide immunity to viral pathogens has positioned them as valuable therapeutic targets for immunomodulation. To become competent as antibody secreting cells, B cells undergo a series of activation steps, which are triggered by the recognition of antigens frequently displayed on the surface of other presenting cells. Such antigens elicit the formation of an immune synapse (IS), where local cytoskeleton rearrangements coupled to mechanical forces and membrane trafficking orchestrate the extraction and processing of antigens in B cells. In this review, we discuss the molecular mechanisms that regulate polarized membrane trafficking and mechanical properties of the immune synapse, as well as the potential extracellular cues from the environment, which may impact the ability of B cells to sense and acquire antigens at the immune synapse. An integrated view of the diverse cellular mechanisms that shape the immune synapse will provide a better understanding on how B cells are efficiently activated.
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Affiliation(s)
- Felipe Del Valle Batalla
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | | | - María-Isabel Yuseff
- Department of Cellular and Molecular Biology, Faculty of Sciences, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile.
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Bretou M, Kumari A, Malbec O, Moreau HD, Obino D, Pierobon P, Randrian V, Sáez PJ, Lennon-Duménil AM. Dynamics of the membrane-cytoskeleton interface in MHC class II-restricted antigen presentation. Immunol Rev 2016; 272:39-51. [DOI: 10.1111/imr.12429] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Marine Bretou
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Anita Kumari
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Odile Malbec
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Hélène D. Moreau
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Dorian Obino
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Paolo Pierobon
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Violaine Randrian
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
| | - Pablo J. Sáez
- Inserm U932, Institut Curie; ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043; Paris France
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Mattila PK, Batista FD, Treanor B. Dynamics of the actin cytoskeleton mediates receptor cross talk: An emerging concept in tuning receptor signaling. J Cell Biol 2016; 212:267-80. [PMID: 26833785 PMCID: PMC4748574 DOI: 10.1083/jcb.201504137] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Recent evidence implicates the actin cytoskeleton in the control of receptor signaling. This may be of particular importance in the context of immune receptors, such as the B cell receptor, where dysregulated signaling can result in autoimmunity and malignancy. Here, we discuss the role of the actin cytoskeleton in controlling receptor compartmentalization, dynamics, and clustering as a means to regulate receptor signaling through controlling the interactions with protein partners. We propose that the actin cytoskeleton is a point of integration for receptor cross talk through modulation of protein dynamics and clustering. We discuss the implication of this cross talk via the cytoskeleton for both ligand-induced and low-level constitutive (tonic) signaling necessary for immune cell survival.
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Affiliation(s)
- Pieta K Mattila
- Institute of Biomedicine, MediCity, University of Turku, 20520 Turku, Finland
| | - Facundo D Batista
- Lymphocyte Interaction Laboratory, The Francis Crick Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Bebhinn Treanor
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M5T 1C6, Canada
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Reversat A, Yuseff MI, Lankar D, Malbec O, Obino D, Maurin M, Penmatcha NVG, Amoroso A, Sengmanivong L, Gundersen GG, Mellman I, Darchen F, Desnos C, Pierobon P, Lennon-Duménil AM. Polarity protein Par3 controls B-cell receptor dynamics and antigen extraction at the immune synapse. Mol Biol Cell 2015; 26:1273-85. [PMID: 25631815 PMCID: PMC4454175 DOI: 10.1091/mbc.e14-09-1373] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
B-cell receptor (BCR) engagement with surface-tethered antigens leads to the formation of an immune synapse, which facilitates antigen uptake for presentation to T-lymphocytes. Antigen internalization and processing rely on the early dynein-dependent transport of BCR-antigen microclusters to the synapse center, as well as on the later polarization of the microtubule-organizing center (MTOC). MTOC repositioning allows the release of proteases and the delivery of MHC class II molecules at the synapse. Whether and how these events are coordinated have not been addressed. Here we show that the ancestral polarity protein Par3 promotes BCR-antigen microcluster gathering, as well as MTOC polarization and lysosome exocytosis, at the synapse by facilitating local dynein recruitment. Par3 is also required for antigen presentation to T-lymphocytes. Par3 therefore emerges as a key molecule in the coupling of the early and late events needed for efficient extraction and processing of immobilized antigen by B-cells.
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Affiliation(s)
- Anne Reversat
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France
| | - Maria-Isabel Yuseff
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France Departamento de Biologia Celular y Molecular, Pontificia Universidad Catolica de Chile, 6513677 Santiago, Chile
| | - Danielle Lankar
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France
| | - Odile Malbec
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France
| | - Dorian Obino
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France
| | - Mathieu Maurin
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France
| | | | - Alejandro Amoroso
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France Facultad de Ciencias de la Salud, Universidad San Sebastián, 7510157 Santiago, Chile
| | - Lucie Sengmanivong
- Cell and Tissue Imaging Core Facility (PICT-IBiSA) and Nikon Imaging Centre, Institut Curie, UMR144, Centre de Recherche, 75005 Paris, France
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | | | - François Darchen
- Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR8250, 75270 Paris Cedex 06, France
| | - Claire Desnos
- Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR8250, 75270 Paris Cedex 06, France
| | - Paolo Pierobon
- INSERM U932, Institut Curie, Centre de Recherche, 75005 Paris, France
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Burbage M, Keppler SJ, Gasparrini F, Martínez-Martín N, Gaya M, Feest C, Domart MC, Brakebusch C, Collinson L, Bruckbauer A, Batista FD. Cdc42 is a key regulator of B cell differentiation and is required for antiviral humoral immunity. J Exp Med 2015; 212:53-72. [PMID: 25547673 PMCID: PMC4291523 DOI: 10.1084/jem.20141143] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 11/25/2014] [Indexed: 12/22/2022] Open
Abstract
The small Rho GTPase Cdc42, known to interact with Wiskott-Aldrich syndrome (WAS) protein, is an important regulator of actin remodeling. Here, we show that genetic ablation of Cdc42 exclusively in the B cell lineage is sufficient to render mice unable to mount antibody responses. Indeed Cdc42-deficient mice are incapable of forming germinal centers or generating plasma B cells upon either viral infection or immunization. Such severe immune deficiency is caused by multiple and profound B cell abnormalities, including early blocks during B cell development; impaired antigen-driven BCR signaling and actin remodeling; defective antigen presentation and in vivo interaction with T cells; and a severe B cell-intrinsic block in plasma cell differentiation. Thus, our study presents a new perspective on Cdc42 as key regulator of B cell physiology.
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Affiliation(s)
- Marianne Burbage
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Selina J Keppler
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Francesca Gasparrini
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Nuria Martínez-Martín
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Mauro Gaya
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Christoph Feest
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Marie-Charlotte Domart
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Cord Brakebusch
- Biomedical Institute, Biotech Research and Innovation Centre, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Lucy Collinson
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Andreas Bruckbauer
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
| | - Facundo D Batista
- Lymphocyte Interaction Laboratory, Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, England, UK
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Abstract
In the early stages of atherosclerotic lesion development, cholesterol is mostly present as esterified cholesterol stored in macrophage cytoplasmic lipid droplets. However, when the lesion evolves, free cholesterol accumulates in other compartments, such as lysosomes and plasma membrane. A number of studies support a role for intracellular cholesterol content and distribution in regulating several cell functions. Particularly, membrane free cholesterol content has a specific effect on signaling pathways involved in regulating cell motility and organization of the actin cytoskeleton. These processes are regulated by several signaling pathways including the small GTPase Rac1. Rac1 belongs to the Rho GTPases of the Ras protein superfamily involved in the regulation of multiple cell functions, including cell proliferation, chemotaxis, phagocytosis, degranulation, and superoxide production. In this review, we discuss the role of Rac1 in macrophage with respect to cholesterol metabolism and trafficking as critical aspects for the development of atherosclerotic plaque.
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10
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Abstract
HIV-1-infected nonprogressors (NP) inhibit disease progression for years without antiretroviral therapy. Defining the mechanisms for this resistance to disease progression could be important in determining strategies for controlling HIV-1 infection. Here we show that two types of professional antigen-presenting cells (APC), i.e., dendritic cells (DC) and B lymphocytes, from NP lacked the ability to mediate HIV-1 trans infection of CD4+ T cells. In contrast, APC from HIV-1-infected progressors (PR) and HIV-1-seronegative donors (SN) were highly effective in mediating HIV-1 trans infection. Direct cis infection of T cells with HIV-1 was comparably efficient among NP, PR, and SN. Lack of HIV-1 trans infection in NP was linked to lower cholesterol levels and an increase in the levels of the reverse cholesterol transporter ABCA1 (ATP-binding cassette transporter A1) in APC but not in T cells. Moreover, trans infection mediated by APC from NP could be restored by reconstitution of cholesterol and by inhibiting ABCA1 by mRNA interference. Importantly, this appears to be an inherited trait, as it was evident in APC obtained from NP prior to their primary HIV-1 infection. The present study demonstrates a new mechanism wherein enhanced lipid metabolism in APC results in remarkable control of HIV-1 trans infection that directly relates to lack of HIV-1 disease progression. HIV-1 can be captured by antigen-presenting cells (APC) such as dendritic cells and transferred to CD4 helper T cells, which results in greatly enhanced viral replication by a mechanism termed trans infection. A small percentage of HIV-1-infected persons are able to control disease progression for many years without antiretroviral therapy. In our study, we linked this lack of disease progression to a profound inability of APC from these individuals to trans infect T cells. This effect was due to altered lipid metabolism in their APC, which appears to be an inherited trait. These results provide a basis for therapeutic interventions to control of HIV-1 infection through modulation of cholesterol metabolism.
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Yuseff MI, Pierobon P, Reversat A, Lennon-Duménil AM. How B cells capture, process and present antigens: a crucial role for cell polarity. Nat Rev Immunol 2013; 13:475-86. [PMID: 23797063 DOI: 10.1038/nri3469] [Citation(s) in RCA: 202] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
B cells are key components of the adaptive immune response. Their differentiation into either specific memory B cells or antibody-secreting plasma cells is a consequence of activation steps that involve the processing and presentation of antigens. The engagement of B cell receptors by surface-tethered antigens leads to the formation of an immunological synapse that coordinates cell signalling events and that promotes antigen uptake for presentation on MHC class II molecules. In this Review, we discuss membrane trafficking and the associated molecular mechanisms that are involved in antigen extraction and processing at the B cell synapse, and we highlight how B cells use cell polarity to coordinate the complex events that ultimately lead to efficient humoral responses.
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Abstract
A large antibody repertoire is generated in developing B cells in the bone marrow. Before these B cells achieve immunocompetence, those expressing autospecificities must be purged. To that end, B cells within the bone marrow and just following egress from the bone marrow are subject to tolerance induction. Once B cells achieve immunocompetence, the antibody repertoire can be further diversified by somatic hypermutation of immunoglobulin genes in B cells that have been activated by antigen and cognate T cell help and have undergone a germinal center (GC) response. This process also leads to the generation of autoreactive B cells which must be again purged to protect the host. Thus, B cells within the GC and just following egress from the GC are also subject to tolerance induction. Available data suggest that B cell intrinsic processes triggered by signaling through the B cell receptor activate tolerance mechanisms at both time points. Recent data suggest that GC and post-GC B cells are also subject to B cell extrinsic tolerance mechanisms mediated through soluble and membrane-bound factors derived from various T cell subsets.
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Andrews SF, Dai X, Ryu BY, Gulick T, Ramachandran B, Rawlings DJ. Developmentally regulated expression of MEF2C limits the response to BCR engagement in transitional B cells. Eur J Immunol 2012; 42:1327-36. [PMID: 22311635 DOI: 10.1002/eji.201142226] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transitional and naïve mature peripheral B cells respond very differently to B-cell receptor (BCR) cross-linking. While transitional B cells undergo apoptosis upon BCR engagement, mature B cells survive and proliferate. This differential response correlates with the capacity of mature, but not transitional B cells to transcribe genes that promote cell survival and proliferation, including those encoding c-Myc and the Bcl-2 family members Bcl-xL and A1. We recently demonstrated that transitional B cells fail to assemble transcriptional machinery at the promoter region of these target genes despite equivalent cytoplasmic signaling and nuclear translocation of key transcription factors including NF-κB and nuclear factor of activated T cells (NFAT). The transcription factor myocyte enhancer factor-2C (MEF2C) is regulated by both calcineurin and mitogen-activated protein kinase signaling pathways, and is essential for proliferation and survival downstream of BCR engagement in mature B cells. In this work, we demonstrate that transitional B cells have intrinsically low levels of MEF2C protein and DNA-binding activity, and that this developmental difference in MEF2C expression is functionally significant. Forced expression of MEF2C in transitional B cells promoted cell survival, proliferation, and upregulation of pro-survival genes. Thus, low MEF2C expression limits transitional B-cell responsiveness to BCR engagement before these cells reach maturity.
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Affiliation(s)
- Sarah F Andrews
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA, USA
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Subcellular distribution of Lck during CD4 T-cell maturation in the thymic medulla regulates the T-cell activation threshold. Proc Natl Acad Sci U S A 2012; 109:7415-20. [PMID: 22529380 DOI: 10.1073/pnas.1119272109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Mature peripheral T cells respond to foreign but not to self-antigens. During development in the thymus, deletion of high-affinity self-reactive immature thymocytes contributes to tolerance of mature T cells. However, double-positive thymocytes are positively selected to survive if they respond to self-peptide-MHC complexes; thus, there must be mechanisms to prevent overt reactivity to those same complexes in the periphery. "Developmental tuning" is the active process through which T-cell receptor (TCR)-associated signaling pathways of single-positive (SP) thymocytes are attenuated to respond appropriately to self-peptide-MHC complexes in the periphery. We previously showed that MHC class II expression in the thymic medulla was necessary to tune CD4(+) SP (CD4 SP) thymocytes. CD4 SP thymocytes from mice lacking medullary MHC class II expression had inappropriately enhanced proximal TCR signaling to low-affinity self-ligands that was associated with altered cellular distribution of the tyrosine kinase Lck. Now, we report that activation of both tuned and untuned CD4 SP thymocytes is Lck-dependent. Untuned CD4 SP cells contain a pool of Lck with increased basal phosphorylation that is not associated with the CD4 coreceptor. Phosphorylation of this pool of Lck decreases with tuning. Immunogold transmission electron microscopy of membrane sheets permitted direct visualization of Lck. In the absence of tuning, a significant proportion of Lck and the TCR subunit CD3ζ are expressed on the same protein island; this close association of Lck and the TCR probably explains the enhanced activation of untuned CD4 SP cells. Thus, changes in membrane topography during thymic maturation determine the set point for TCR responsiveness.
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Polarized Secretion of Lysosomes at the B Cell Synapse Couples Antigen Extraction to Processing and Presentation. Immunity 2011; 35:361-74. [DOI: 10.1016/j.immuni.2011.07.008] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/30/2011] [Accepted: 07/08/2011] [Indexed: 11/17/2022]
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Calandra S, Tarugi P, Speedy HE, Dean AF, Bertolini S, Shoulders CC. Mechanisms and genetic determinants regulating sterol absorption, circulating LDL levels, and sterol elimination: implications for classification and disease risk. J Lipid Res 2011; 52:1885-926. [PMID: 21862702 DOI: 10.1194/jlr.r017855] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestinal and hepatic-derived lipoprotein remnants (LDLR, APOB, APOE, LDLRAP1, PCSK9, IDOL). The insights gained from integrating the wealth of genetic data with biological processes have important implications for the classification of clinical and presymptomatic diagnoses of traditional LDL dyslipidemias, sitosterolemia, and newly emerging phenotypes, as well as their management through both nutritional and pharmaceutical means.
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Affiliation(s)
- Sebastiano Calandra
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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17
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Abstract
B cell activation is initiated by the ligation of the B cell receptor (BCR) with antigen and ultimately results in the production of protective antibodies against potentially pathogenic invaders. Here we review recent literature concerned with the spatiotemporal dynamic characterization of the early molecular events of B cell activation, including the initiation of BCR triggering, the formation of BCR microclusters, and the dynamic regulation of BCR signaling. Because these events involve the considerable reorganization of molecules within the membrane, an important role for the cytoskeleton is emerging in the regulation of B cell activation. At each stage we highlight the role of the cytoskeleton, establishing its pivotal position during the initiation and regulation of B cell activation.
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Affiliation(s)
- Naomi E. Harwood
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3PX, United Kingdom
| | - Facundo D. Batista
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3PX, United Kingdom
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18
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Yuseff MI, Lankar D, Lennon-Duménil AM. Dynamics of membrane trafficking downstream of B and T cell receptor engagement: impact on immune synapses. Traffic 2009; 10:629-36. [PMID: 19416472 PMCID: PMC2723867 DOI: 10.1111/j.1600-0854.2009.00913.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Accepted: 03/12/2009] [Indexed: 12/01/2022]
Abstract
The onset of an adaptive immune response requires the activation of T and B lymphocytes by antigen-presenting cells, through a specialized form of intercellular communication, known as the immunological synapse (IS). In B lymphocytes the IS promotes efficient recognition and acquisition of membrane-bound Ags, while in T cells, it modulates the T cell response upon exposure to peptide-major histocompatibility complexes. In this review, we highlight the similarities that determine B and T cell activation, focusing on immune receptor downstream signaling events that lead to synapse formation. We stress the notion that polarization of T and B lymphocytes characterized by global changes in cytoskeleton and membrane trafficking modulates synapse structure and function, thus determining lymphocyte effector functions and fate.
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Affiliation(s)
| | - Danielle Lankar
- INSERM U932, Institut Curie12 rue Lhomond, 75005, Paris, France
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19
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Andrews SF, Rawlings DJ. Transitional B cells exhibit a B cell receptor-specific nuclear defect in gene transcription. THE JOURNAL OF IMMUNOLOGY 2009; 182:2868-78. [PMID: 19234182 DOI: 10.4049/jimmunol.0802368] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The signaling programs that enforce negative selection in early transitional (T1) B cells in response to BCR engagement remain poorly defined. We conducted a comprehensive comparison of BCR signaling in T1 vs follicular mature splenic B cells. T1, in contrast to follicular mature B cells, failed to express key NF-kappaB target genes in response to BCR engagement and exhibited a striking defect in assembly of an active transcriptional complex at the promoter of the survival and proliferative genes A1 and c-Myc. Surprisingly, and contrary to previous models, classical protein kinase C and IkappaB kinase activation, NF-kappaB nuclear translocation and DNA binding were intact in T1 B cells. Furthermore, despite a marked reduction in NFAT1 expression, differential NFAT or AP-1 activation cannot explain this transcriptional defect. Our combined findings demonstrate that T1 B cells are programmed for signal- and stage-specific "nuclear nonresponsiveness" upon encounter with self-Ags.
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Affiliation(s)
- Sarah F Andrews
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA
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20
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Imamura Y, Oda A, Katahira T, Bundo K, Pike KA, Ratcliffe MJH, Kitamura D. BLNK binds active H-Ras to promote B cell receptor-mediated capping and ERK activation. J Biol Chem 2009; 284:9804-13. [PMID: 19218240 DOI: 10.1074/jbc.m809051200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cross-linked B cell receptor (BCR) aggregates on the cell surface, then assembles into the "cap" where Ras is co-localized, and transduces various intracellular signals including Ras-ERK activation. BCR signals induce proliferation, differentiation, or apoptosis of B cells depending on their maturational stage. The adaptor protein BLNK binds various signaling proteins and Igalpha, a signaling subunit of the BCR complex, and plays an important role in the BCR signal transduction. BLNK was shown to be required for activation of ERK, but not of Ras, after BCR cross-linking, raising a question how BLNK facilitates ERK activation. Here we demonstrate that BLNK binds the active form of H-Ras, and their binding is facilitated by BCR cross-linking. We have identified a 10-amino acid Ras-binding domain within BLNK that is necessary for restoration of BCR-mediated ERK activation in BLNK-deficient B cells and for anti-apoptotic signaling. The Ras-binding domain fused with a CD8alpha-Igalpha chimeric receptor could induce prolonged ERK phosphorylation, transcriptional activation of Elk1, as well as the capping of the receptor in BLNK-deficient B cells. These results indicate that BLNK recruits active H-Ras to the BCR complex, which is essential for sustained surface expression of BCR in the form of the cap and for the signal leading to functional ERK activation.
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Affiliation(s)
- Yasuhiro Imamura
- Division of Molecular Biology, Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda, Chiba 278-0022, Japan
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21
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Tonic B cell antigen receptor signals supply an NF-kappaB substrate for prosurvival BLyS signaling. Nat Immunol 2008; 9:1379-87. [PMID: 18978795 DOI: 10.1038/ni.1666] [Citation(s) in RCA: 165] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Accepted: 09/22/2008] [Indexed: 11/08/2022]
Abstract
The survival of transitional and mature B cells requires both the B cell antigen receptor (BCR) and BLyS receptor 3 (BR3), which suggests that these receptors send signals that are nonredundant or that engage in crosstalk with each other. Here we show that BCR signaling induced production of the nonclassical transcription factor NF-kappaB pathway substrate p100, which is required for transmission of BR3 signals and thus B cell survival. The capacity for sustained p100 production emerged during transitional B cell differentiation, the stage at which BCR signals begin to mediate survival rather than negative selection. Our findings identify a molecular mechanism for the reliance of primary B cells on continuous BR3 and BCR signaling, as well as for the gradual resistance to negative selection that is acquired during B cell maturation.
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22
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Abstract
The appropriate activation of B cells is critical for the development and operation of immune responses and is dependent on the extensive coordination of intra- and intercellular communications in response to antigen stimulation. An accurate description of the B cell-activation process requires investigation of these interactions within their correct cellular context both at high resolution and in real time. Here, we discuss a number of recent studies that have offered insight into the early molecular events of B cell activation. We suggest that segregation within the B cell membrane triggers localized cytoskeleton reorganisation and signaling, allowing the formation of B cell receptor (BCR) microclusters. These BCR microclusters are the sites for the coordinated recruitment of the signalosome and are propagated during B cell spreading. We discuss the recent identification of a critical role for CD19 in the B cell response to membrane-bound antigen and suggest a mechanism involving BCR microclusters by which it mediates its stimulatory function. Finally, we consider research that has taken advantage of recent technological advances in multiphoton microscopy that have allowed its application to the investigation of the dynamics of membrane-bound antigen presentation and subsequent B cell activation in lymph nodes in vivo.
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Affiliation(s)
- Naomi E Harwood
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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23
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Weber M, Treanor B, Depoil D, Shinohara H, Harwood NE, Hikida M, Kurosaki T, Batista FD. Phospholipase C-gamma2 and Vav cooperate within signaling microclusters to propagate B cell spreading in response to membrane-bound antigen. ACTA ACUST UNITED AC 2008; 205:853-68. [PMID: 18362175 PMCID: PMC2292224 DOI: 10.1084/jem.20072619] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
B cell receptor (BCR) recognition of membrane-bound antigen initiates a spreading and contraction response, the extent of which is controlled through the formation of signaling-active BCR-antigen microclusters and ultimately affects the outcome of B cell activation. We followed a genetic approach to define the molecular requirements of BCR-induced spreading and microcluster formation. We identify a key role for phospholipase C-γ2 (PLCγ2), Vav, B cell linker, and Bruton's tyrosine kinase in the formation of highly coordinated “microsignalosomes,” the efficient assembly of which is absolutely dependent on Lyn and Syk. Using total internal reflection fluorescence microscopy, we examine at high resolution the recruitment of PLCγ2 and Vav to microsignalosomes, establishing a novel synergistic relationship between the two. Thus, we demonstrate the importance of cooperation between components of the microsignalosome in the amplification of signaling and propagation of B cell spreading, which is critical for appropriate B cell activation.
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Affiliation(s)
- Michele Weber
- Lymphocyte Interaction Laboratory, London Research Institute, Cancer Research UK, London WC2A 3PX, England, UK
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