title: WASp-dependent actin cytoskeleton stability at the dendritic cell immunological synapse is required for extensive, functional T cell contacts.
abstract: The immunological synapse is a highly structured and molecularly dynamic interface between communicating immune cells. Although the immunological synapse promotes T cell activation by dendritic cells, the specific organization of the immunological synapse on the dendritic cell side in response to T cell engagement is largely unknown. In this study, confocal and electron microscopy techniques were used to investigate the role of dendritic cell actin regulation in immunological synapse formation, stabilization, and function. In the dendritic cell-restricted absence of the Wiskott-Aldrich syndrome protein, an important regulator of the actin cytoskeleton in hematopoietic cells, the immunological synapse contact with T cells occupied a significantly reduced surface area. At a molecular level, the actin network localized to the immunological synapse exhibited reduced stability, in particular, of the actin-related protein-2/3-dependent, short-filament network. This was associated with decreased polarization of dendritic cell-associated ICAM-1 and MHC class II, which was partially dependent on Wiskott-Aldrich syndrome protein phosphorylation. With the use of supported planar lipid bilayers incorporating anti-ICAM-1 and anti-MHC class II antibodies, the dendritic cell actin cytoskeleton organized into recognizable synaptic structures but interestingly, formed Wiskott-Aldrich syndrome protein-dependent podosomes within this area. These findings demonstrate that intrinsic dendritic cell cytoskeletal remodeling is a key regulatory component of normal immunological synapse formation, likely through consolidation of adhesive interaction and modulation of immunological synapse stability.
authors.affiliation: Molecular Immunology Unit, University College London Institute of Child Health, London, United Kingdom;
authors.forename: Dessislava
authors.initials: D
authors.lastname: Malinova
authors.affiliation: London Centre for Nanotechnology and Department of Cell and Developmental Biology, University College London, London, United Kingdom;
authors.forename: Marco
authors.initials: M
authors.lastname: Fritzsche
authors.affiliation: Division of Immune Cell Biology, Medical Research Council National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom;
authors.forename: Carla R
authors.initials: CR
authors.lastname: Nowosad
authors.affiliation: Imaging Unit, University College London Institute of Ophthalmology, London, United Kingdom; and.
authors.forename: Hannah
authors.initials: H
authors.lastname: Armer
authors.affiliation: Imaging Unit, University College London Institute of Ophthalmology, London, United Kingdom; and.
authors.forename: Peter M G
authors.initials: PM
authors.lastname: Munro
authors.affiliation: Molecular Immunology Unit, University College London Institute of Child Health, London, United Kingdom;
authors.forename: Michael P
authors.initials: MP
authors.lastname: Blundell
authors.affiliation: London Centre for Nanotechnology and Department of Cell and Developmental Biology, University College London, London, United Kingdom;
authors.forename: Guillaume
authors.initials: G
authors.lastname: Charras
authors.affiliation: Division of Immune Cell Biology, Medical Research Council National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom;
authors.forename: Pavel
authors.initials: P
authors.lastname: Tolar
authors.affiliation: Molecular Immunology Unit, University College London Institute of Child Health, London, United Kingdom;
authors.forename: Gerben
authors.initials: G
authors.lastname: Bouma
authors.affiliation: Molecular Immunology Unit, University College London Institute of Child Health, London, United Kingdom; Great Ormond Street Hospital for Children, National Health Service Foundation Trust, London, United Kingdom a.thrasher@ucl.ac.uk.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Thrasher
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D002450:Cell Communication / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology*; D036681:Fluorescence Recovery After Photobleaching; D054992:Immunological Synapses / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008810:Mice, Inbred C57BL; D000069261:Podosomes / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D051316:Wiskott-Aldrich Syndrome Protein / Q000378:metabolism*
chemical_list: D008051:Lipid Bilayers; D051316:Wiskott-Aldrich Syndrome Protein; D018799:Intercellular Adhesion Molecule-1
keywords: Arp2/3; DC; FRAP; ICAM-1; podosomes