title: Secretory cytotoxic granule maturation and exocytosis require the effector protein hMunc13-4.
abstract: Cytotoxic T lymphocytes and natural killer cells exert their cytotoxic activity through the polarized secretion of cytotoxic granules at the immunological synapse. Rab27a and hMunc13-4 are critical effectors of the exocytosis of cytotoxic granules. Here we show that the cytotoxic function of lymphocytes requires the cooperation of two types of organelles: the lysosomal cytotoxic granule and the endosomal 'exocytic vesicle'. Independently of Rab27a, hMunc13-4 mediated the assembly of Rab11(+) recycling and Rab27(+) late endosomal vesicles, constituting a pool of vesicles destined for regulated exocytosis. It also primed cytotoxic granule fusion, possibly through interaction with active Rab27a. Cytotoxic T lymphocyte-target cell recognition induced rapid polarization of both types of organelles, which coalesced near the cell-cell contact area. Our data provide insight into the regulation of the generation and release of cytotoxic granules by effector cytotoxic T lymphocytes and natural killer cells.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale Unité 768, Laboratoire du Développement Normal et Pathologique du Système Immunitaire, Paris F-75015 France.
authors.forename: Mickaël M
authors.initials: MM
authors.lastname: Ménager
authors.forename: Gaël
authors.initials: G
authors.lastname: Ménasché
authors.forename: Maryse
authors.initials: M
authors.lastname: Romao
authors.forename: Perrine
authors.initials: P
authors.lastname: Knapnougel
authors.forename: Chen-Hsuan
authors.initials: CH
authors.lastname: Ho
authors.forename: Mériem
authors.initials: M
authors.lastname: Garfa
authors.forename: Graça
authors.initials: G
authors.lastname: Raposo
authors.forename: Jérôme
authors.initials: J
authors.lastname: Feldmann
authors.forename: Alain
authors.initials: A
authors.lastname: Fischer
authors.forename: Geneviève
authors.initials: G
authors.lastname: de Saint Basile
mesh_terms: D016764:Cell Polarity; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000502:physiology*; D011992:Endosomes / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D008213:Lymphocyte Activation / Q000276:immunology; D008247:Lysosomes / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000276:immunology* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D022142:Secretory Vesicles / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism; D000075745:rab27 GTP-Binding Proteins
chemical_list: D009419:Nerve Tissue Proteins; C485548:UNC13B protein, human; D000075745:rab27 GTP-Binding Proteins; C066694:RAB27A protein, human; D020691:rab GTP-Binding Proteins