title: CD81 controls sustained T cell activation signaling and defines the maturation stages of cognate immunological synapses.
abstract: In this study, we investigated the dynamics of the molecular interactions of tetraspanin CD81 in T lymphocytes, and we show that CD81 controls the organization of the immune synapse (IS) and T cell activation. Using quantitative microscopy, including fluorescence recovery after photobleaching (FRAP), phasor fluorescence lifetime imaging microscopy-Föster resonance energy transfer (phasorFLIM-FRET), and total internal reflection fluorescence microscopy (TIRFM), we demonstrate that CD81 interacts with ICAM-1 and CD3 during conjugation between T cells and antigen-presenting cells (APCs). CD81 and ICAM-1 exhibit distinct mobilities in central and peripheral areas of early and late T cell-APC contacts. Moreover, CD81-ICAM-1 and CD81-CD3 dynamic interactions increase over the time course of IS formation, as these molecules redistribute throughout the contact area. Therefore, CD81 associations unexpectedly define novel sequential steps of IS maturation. Our results indicate that CD81 controls the temporal progression of the IS and the permanence of CD3 in the membrane contact area, contributing to sustained T cell receptor (TCR)-CD3-mediated signaling. Accordingly, we find that CD81 is required for proper T cell activation, regulating CD3ζ, ZAP-70, LAT, and extracellular signal-regulated kinase (ERK) phosphorylation; CD69 surface expression; and interleukin-2 (IL-2) secretion. Our data demonstrate the important role of CD81 in the molecular organization and dynamics of the IS architecture that sets the signaling threshold in T cell activation.
authors.affiliation: Servicio de Inmunología, Hospital de la Princesa, Instituto de Investigación Sanitaria La Princesa, Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Rocha-Perugini
authors.forename: M
authors.initials: M
authors.lastname: Zamai
authors.forename: J M
authors.initials: JM
authors.lastname: González-Granado
authors.forename: O
authors.initials: O
authors.lastname: Barreiro
authors.forename: E
authors.initials: E
authors.lastname: Tejera
authors.forename: M
authors.initials: M
authors.lastname: Yañez-Mó
authors.forename: V R
authors.initials: VR
authors.lastname: Caiolfa
authors.forename: F
authors.initials: F
authors.lastname: Sanchez-Madrid
mesh_terms: D000938:Antigen-Presenting Cells / Q000276:immunology; D017252:CD3 Complex / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D036681:Fluorescence Recovery After Photobleaching; D031541:Fluorescence Resonance Energy Transfer; D057809:HEK293 Cells; D006801:Humans; D054992:Immunological Synapses / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D008856:Microscopy, Fluorescence; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D060225:Tetraspanin 28 / Q000378:metabolism*
chemical_list: D017252:CD3 Complex; C554798:CD81 protein, human; C573420:ICAM1 protein, human; D060225:Tetraspanin 28; D018799:Intercellular Adhesion Molecule-1