title: Sustained LFA-1 cluster formation in the immune synapse requires the combined activities of L-plastin and calmodulin.
abstract: Formation of immune synapses (IS) between T cells and APC requires multiple rearrangements in the actin cytoskeleton and selective receptor accumulation in supramolecular activation clusters (SMAC). The inner cluster (central SMAC) contains the TCR/CD3 complex. The outer cluster (peripheral SMAC) contains the integrin LFA-1 and Talin. Molecular mechanisms selectively stabilizing receptors in the IS remained largely unknown. Here, we demonstrate that sustained LFA-1 clustering in the IS is a consequence of the combined activities of the actin-bundling protein L-plastin (LPL) and calmodulin. Thus, upon antigen-recognition of T cells, LPL accumulated predominantly in the peripheral SMAC. siRNA-mediated knock-down of LPL led to a failure of LFA-1 and Talin redistribution - however, not TCR/CD3 relocalization - into the IS. As a result of this LPL knock-down, the T-cell/APC interface became smaller over time and T-cell proliferation was inhibited. Importantly, binding of calmodulin to LPL was required for the maintenance of LPL in the IS and consequently inhibition of calmodulin also prevented stable accumulation of LFA-1 and Talin, but not CD3, in the IS.
authors.affiliation: Institute for Immunology, Ruprecht-Karls-University, Heidelberg, Germany. guido.wabnitz@immu.uni-heidelberg.de
authors.forename: Guido H
authors.initials: GH
authors.lastname: Wabnitz
authors.forename: Philipp
authors.initials: P
authors.lastname: Lohneis
authors.forename: Henning
authors.initials: H
authors.lastname: Kirchgessner
authors.forename: Beate
authors.initials: B
authors.lastname: Jahraus
authors.forename: Susan
authors.initials: S
authors.lastname: Gottwald
authors.forename: Mathias
authors.initials: M
authors.lastname: Konstandin
authors.forename: Martin
authors.initials: M
authors.lastname: Klemke
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Samstag
mesh_terms: D000199:Actins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D001665:Binding Sites / Q000235:genetics; D002147:Calmodulin / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003001:Cloning, Molecular; D004768:Enterotoxins / Q000378:metabolism; D006801:Humans; D054992:Immunological Synapses / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000276:immunology / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018613:Microscopy, Confocal; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology
chemical_list: D000199:Actins; D002147:Calmodulin; D004768:Enterotoxins; D016169:Lymphocyte Function-Associated Antigen-1; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D034741:RNA, Small Interfering; D013449:Sulfonamides; C026742:plastin; C031818:enterotoxin B, staphylococcal; C017967:W 7