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1. Microvilli-derived Extracellular Vesicles Govern Morphogenesis in Drosophila wing epithelium

Author

Graça Raposo, Laurent Ruel, Gisela D’Angelo, Anne-Sophie Macé, Renata Basto, Maryse Romao, Lucie Sengmanivong, Ilse Hurbain, Pascal P. Thérond, Centre de recherche de l'Institut Curie [Paris], Institut Curie [Paris], Structure and Membrane Compartments [Paris], Biologie Cellulaire et Cancer, Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), BioImaging Cell and Tissue Core Facility (PICT-IBiSA), Institut de signalisation, biologie du développement et cancer (ISBDC), Centre National de la Recherche Scientifique (CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), Institut de Biologie Valrose (IBV), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA), Compartimentation et dynamique cellulaires (CDC), Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Université Pierre et Marie Curie - Paris 6 (UPMC), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut Curie [Paris]-Centre National de la Recherche Scientifique (CNRS)

Subjects
0303 health sciences, animal structures, Chemistry, [SDV]Life Sciences [q-bio], Morphogenesis, Extracellular vesicle, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Epithelium, Cell biology, 03 medical and health sciences, 0302 clinical medicine, medicine.anatomical_structure, embryonic structures, medicine, Secretion, Cytoskeleton, Hedgehog, 030217 neurology & neurosurgery, Biogenesis, 030304 developmental biology, Morphogen
Abstract

The regulation and coordination of developmental processes involves the secretion of morphogens and membrane carriers, including extracellular vesicles, which facilitate their transport over long distance. The long-range activity of the Hedgehog morphogen is conveyed by extracellular vesicles. However, the site and the molecular basis of their biogenesis remains unknown. By combining fluorescence and electron microscopy combined with genetics and cell biology approaches, we investigated the origin and the cellular mechanisms underlying extracellular vesicle biogenesis, and their contribution to Drosophila wing disc development, exploiting Hedgehog as a long-range morphogen. We show that microvilli of Drosophila wing disc epithelium are the site of generation of small extracellular vesicles that transport Hedgehog across the tissue. This process requires the Prominin-like protein, whose activity, together with interacting cytoskeleton components and lipids, is critical for maintaining microvilli integrity and function in secretion. Our results provide the first evidence that microvilli-derived extracellular vesicles contribute to Hedgehog long-range signaling activity highlighting their physiological significance in tissue development in vivo.

Published
2021

2. Coronin 1C promotes triple-negative breast cancer invasiveness through regulation of MT1-MMP traffic and invadopodia function

Author

Graça Raposo, Thierry Dubois, Sophie Vacher, Ivan Bièche, Sonia Agüera-Gonzalez, Laetitia Fuhrmann, Maryse Romao, Anne Vincent-Salomon, Carole El Kesrouani, Marie Irondelle, Alan Guichard, Alessia Castagnino, Catalina Lodillinsky, James E. Bear, Anna Zagryazhskaya-Masson, Christoph S. Clemen, Philippe Chavrier, Antonio Castro-Castro, Angelika A. Noegel, and Institut Curie [Paris]

Subjects
0301 basic medicine, Cancer Research, Podosome, [SDV]Life Sciences [q-bio], Triple Negative Breast Neoplasms, macromolecular substances, Metastasis, 03 medical and health sciences, Mice, Actin filament branching, Cell Line, Tumor, Spheroids, Cellular, Genetics, medicine, Matrix Metalloproteinase 14, Animals, Humans, Neoplasm Invasiveness, Molecular Biology, Triple-negative breast cancer, ComputingMilieux_MISCELLANEOUS, Tumor microenvironment, biology, Microfilament Proteins, Cancer, medicine.disease, Protein Transport, 030104 developmental biology, Invadopodia, Podosomes, biology.protein, Cancer research, Heterografts, Female, Cortactin
Abstract

Membrane type 1-matrix metalloproteinase (MT1-MMP), a membrane-tethered protease, is key for matrix breakdown during cancer invasion and metastasis. Assembly of branched actin networks by the Arp2/3 complex is required for MT1-MMP traffic and formation of matrix-degradative invadopodia. Contrasting with the well-established role of actin filament branching factor cortactin in invadopodia function during cancer cell invasion, the contribution of coronin-family debranching factors to invadopodia-based matrix remodeling is not known. Here, we investigated the contribution of coronin 1C to the invasive potential of breast cancer cells. We report that expression of coronin 1C is elevated in invasive human breast cancers, correlates positively with MT1-MMP expression in relation with increased metastatic risk and is a new independent prognostic factor in breast cancer. We provide evidence that, akin to cortactin, coronin 1C is required for invadopodia formation and matrix degradation by breast cancer cells lines and for 3D collagen invasion by multicellular spheroids. Using intravital imaging of orthotopic human breast tumor xenografts, we find that coronin 1C accumulates in structures forming in association with collagen fibrils in the tumor microenvironment. Moreover, we establish the role of coronin 1C in the regulation of positioning and trafficking of MT1-MMP-positive endolysosomes. These results identify coronin 1C as a novel player of the multi-faceted mechanism responsible for invadopodia formation, MT1-MMP surface exposure and invasiveness in breast cancer cells.

Published
2018

3. Nucleoside diphosphate kinases fuel dynamin superfamily proteins with GTP for membrane remodeling

Author

Ioan Lascu, Graça Raposo, Céline Desbourdes, Philippe Chavrier, Nathalie Sauvonnet, Thibault Lagache, Guillaume Montagnac, Jérôme Guitton, Qinfang Shen, Aurélien Roux, Marie-Lise Lacombe, Maryse Romao, Uwe Schlattner, Lorena Griparic, AlexanderM van der Bliek, Mathieu Boissan, Simona Polo, Institut Curie [Paris], Pathologies biliaires, fibrose et cancer du foie [CHU Saint-Antoine], Centre de Recherche Saint-Antoine (CR Saint-Antoine), Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Saint-Antoine [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Saint-Antoine [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Dynamique de la membrane et du cytosquelette, Compartimentation et dynamique cellulaires (CDC), Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), David Geffen School of Medicine [Los Angeles], University of California [Los Angeles] (UCLA), University of California-University of California, Hospices Civils de Lyon (HCL), Université de Lyon, Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Biologie des Interactions Cellulaires (BIC), Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Analyse d'images biologiques - Biological Image Analysis (BIA), Institut de biochimie et génétique cellulaires (IBGC), Université Bordeaux Segalen - Bordeaux 2-Centre National de la Recherche Scientifique (CNRS), Laboratoire de bioénergétique fondamentale et appliquée (LBFA), Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Santé et de la Recherche Médicale (INSERM), IFOM, Istituto FIRC di Oncologia Molecolare (IFOM), Università degli Studi di Milano [Milano] (UNIMI), University of Geneva [Switzerland], This work was supported by Institut Curie, CNRS, Fondation ARC pour la Recherche sur le Cancer, Groupement des Entreprises Françaises contre le Cancer, Fondation pour la Recherche Médicale, the Human Frontier Science Program, the Swiss National Fund for Research Grant, and the European Research Council., Pathologies biliaires, fibrose et cancer du foie [CRSA], Centre de Recherche Saint-Antoine (CRSA), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), University of California (UC)-University of California (UC), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Milano = University of Milan (UNIMI), and Université de Genève = University of Geneva (UNIGE)

Subjects
endocrine system, MESH: GTP Phosphohydrolases, GTP', MESH: Mitochondria, [SDV]Life Sciences [q-bio], MESH: Guanosine Diphosphate, Biology, Guanosine triphosphate, MESH: Membrane Fusion, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, MESH: Adenosine Triphosphate, MESH: Animals, Nucleoside Diphosphate Kinase D, 030304 developmental biology, Dynamin, 0303 health sciences, Multidisciplinary, MESH: Guanosine Triphosphate, MESH: Humans, Kinase, Cell biology, MESH: Cell Line, MESH: Dynamins, MESH: Intracellular Membranes, chemistry, Guanosine diphosphate, 030220 oncology & carcinogenesis, ddc:540, MESH: Endocytosis, MESH: Coated Pits, Cell-Membrane, GTP Phosphohydrolases, MESH: NM23 Nucleoside Diphosphate Kinases, MESH: Nucleoside Diphosphate Kinase D, Adenosine triphosphate, MESH: Cell Membrane
Abstract

Supplying power: Right time, right place Cell membranes are very flexible and easily molded to shape; however, to physically pinch off a membrane vesicle from a membrane tube still requires power. A type of molecular machine known as dynamin is involved in this sort of membrane remodeling. Dynamins use guanosine triphosphate (GTP) rather than the more commonly used cellular energy source adenosine triphosphate to work. Boissan et al. now show that two separate dynamins found in the cytoplasm or the mitochondria both use the same sort of enzyme—nucleoside diphosphate kinases—to provide GTP at just the right time and the right place to power membrane fission. Science , this issue p. 1510

Published
2014

4. Symmetry breaking in spore germination relies on an interplay between polar cap stability and spore wall mechanics

Author

Jean-Daniel Julien, Daria Bonazzi, Matthieu Piel, Nicolas Minc, Maryse Romao, Arezki Boudaoud, Rima Seddiki, Institut Jacques Monod (IJM (UMR_7592)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Compartimentation et dynamique cellulaires (CDC), Centre National de la Recherche Scientifique (CNRS)-Institut Curie-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire Joliot Curie, École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique de l'ENS Lyon (Phys-ENS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Reproduction et développement des plantes (RDP), École normale supérieure - Lyon (ENS Lyon)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Institut Curie PhD fellowship, European Research Council starting grant (PhyMorph, #307387), CNRS, FP7 (CIG and ITN programs), ANR (grant 10PDOC00301), FRM (grant AJE20130426890), Mairie de Paris 'Emergence grant.', Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut Curie [Paris]-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), École normale supérieure de Lyon (ENS de Lyon)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Université Pierre et Marie Curie - Paris 6 (UPMC), École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon

Subjects
Polarity (physics), Morphogenesis, Biology, Cell Enlargement, Mechanotransduction, Cellular, Time-Lapse Imaging, General Biochemistry, Genetics and Molecular Biology, 03 medical and health sciences, 0302 clinical medicine, MESH: Cell Wall, Cell Wall, MESH: Spores, Fungal, Schizosaccharomyces, Spore germination, Image Processing, Computer-Assisted, Symmetry breaking, Mechanotransduction, MESH: Time-Lapse Imaging, Molecular Biology, Process (anatomy), [SDV.BDD]Life Sciences [q-bio]/Development Biology, MESH: Cell Enlargement, 030304 developmental biology, 0303 health sciences, MESH: Mechanotransduction, Cellular, Cell Polarity, MESH: Schizosaccharomyces pombe Proteins, Cell Biology, Mechanics, Spores, Fungal, MESH: Image Processing, Computer-Assisted, MESH: Morphogenesis, Spore, MESH: Schizosaccharomyces, Polar tube, Schizosaccharomyces pombe Proteins, MESH: Cell Polarity, 030217 neurology & neurosurgery, Developmental Biology
Abstract

International audience; The morphogenesis of single cells depends on their ability to coordinate surface mechanics and polarity. During germination, spores of many species develop a polar tube that hatches out of a rigid outer spore wall (OSW) in a process termed outgrowth. However, how these awakening cells reorganize to stabilize this first growth axis remains unknown. Here, using quantitative experiments and modeling, we reveal the mechanisms underlying outgrowth in fission yeast. We find that, following an isotropic growth phase during which a single polarity cap wanders around the surface, outgrowth occurs when spores have doubled their volume, concomitantly with the stabilization of the cap and a singular rupture in the OSW. This rupture happens when OSW mechanical stress exceeds a threshold, releases the constraints of the OSW on growth, and stabilizes polarity. Thus, outgrowth exemplifies a self-organizing morphogenetic process in which reinforcements between growth and polarity coordinate mechanics and internal organization.

Published
2014

5. Diaphanous-related formins are required for invadopodia formation and invasion of breast tumor cells

Author

Floria Lizárraga, Guillaume Montagnac, Maryse Romao, Guillem Rigaill, Graça Raposo, Gaëlle Le Dez, Isabelle Bonne, Renaud Poincloux, Philippe Chavrier, Institut Curie [Paris], Institut Pasteur [Paris], Institut des Sciences des Plantes de Paris-Saclay (IPS2 (UMR_9213 / UMR_1403)), Institut National de la Recherche Agronomique (INRA)-Université Paris-Sud - Paris 11 (UP11)-Université Paris Diderot - Paris 7 (UPD7)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Microscopie ultrastructurale (plate-forme), and Institut Pasteur [Paris] (IP)

Subjects
Cancer Research, Small interfering RNA, Pathology, medicine.medical_specialty, tumor, [SDV]Life Sciences [q-bio], Formins, Breast Neoplasms, macromolecular substances, Adenocarcinoma, Basement Membrane, Extracellular matrix, 03 medical and health sciences, 0302 clinical medicine, Microscopy, Electron, Transmission, Cell Line, Tumor, medicine, Matrix Metalloproteinase 14, Humans, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, Neoplasm Invasiveness, Cytoskeleton, membrane, Actin, 030304 developmental biology, Adaptor Proteins, Signal Transducing, 0303 health sciences, Matrigel, biology, Actins, Cell biology, Extracellular Matrix, Oncology, 030220 oncology & carcinogenesis, Invadopodia, biology.protein, cells, nucleators, Cortactin
Abstract

Proteolytic degradation of the extracellular matrix by metastatic tumor cells is initiated by the formation of invadopodia, i.e., actin-driven filopodia-like membrane protrusions endowed with matrix-degradative activity. A signaling cascade involving neural Wiskott-Aldrich syndrome protein and the Arp2/3 actin nucleating complex is involved in actin assembly at invadopodia. Yet, the mechanism of invadopodia formation is poorly understood. Based on their role as actin nucleators in cytoskeletal rearrangements, including filopodia formation, we examined the function of Diaphanous-related formins (DRF) in invadopodia formation and invasion by breast tumor cells. Using small interfering RNA silencing of protein expression in highly invasive MDA-MB-231 breast adenocarcinoma cells, we show that three members of the DRF family (DRF1–DRF3) are required for invadopodia formation and two-dimensional matrix proteolysis. We also report that invasion of a three-dimensional Matrigel matrix involves filopodia-like protrusions enriched for invadopodial proteins, including membrane type 1 matrix metalloproteinase, which depend on DRFs for their formation. These data identify DRFs as critical components of the invasive apparatus of tumor cells in two-dimensional and three-dimensional matrices and suggest that different types of actin nucleators cooperate during the formation of invadopodia. [Cancer Res 2009;69(7):2792–800]

Published
2009

6. Secretory cytotoxic granule maturation and exocytosis require the effector protein hMunc13-4

Author

Gaël Ménasché, Geneviève de Saint Basile, Chen-Hsuan Ho, Alain Fischer, Jérôme Feldmann, Maryse Romao, Mériem Garfa, Mickaël M. Ménager, Perrine Knapnougel, Graça Raposo, Developpement Normal et Pathologique du Système Immunitaire, Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Compartimentation et dynamique cellulaires (CDC), Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Université Pierre et Marie Curie - Paris 6 (UPMC), Unité d'Immunologie et d'Hématologie Pédiatrique (CHU Necker - Enfants Malades [AP-HP]), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-CHU Necker - Enfants Malades [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Supported by the Institut National de la Santé et de la Recherche Médicale, Agence Nationale de la Recherche, Action Concertée du Ministère de l’Education Nationale et de la Recherche (BCMS103), and Ministère de l’Education Nationale de la Recherche et de la Technologie (M.M.M.)., Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut Curie [Paris]-Centre National de la Recherche Scientifique (CNRS), and Ménasché, Gaël

Subjects
Cytotoxicity, Immunologic, [SDV.IMM] Life Sciences [q-bio]/Immunology, [SDV]Life Sciences [q-bio], Immunology, Immunoblotting, Fluorescent Antibody Technique, Nerve Tissue Proteins, Endosomes, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Biology, Lymphocyte Activation, Transfection, Polymerase Chain Reaction, Exocytosis, rab27 GTP-Binding Proteins, 03 medical and health sciences, 0302 clinical medicine, Microscopy, Electron, Transmission, Immunology and Allergy, Cytotoxic T cell, Humans, Immunoprecipitation, Microscopy, Immunoelectron, [SDV.BC] Life Sciences [q-bio]/Cellular Biology, Cells, Cultured, 030304 developmental biology, 0303 health sciences, Lymphokine-activated killer cell, Effector, Secretory Vesicles, Granule (cell biology), Degranulation, Cell Polarity, Cell biology, [SDV] Life Sciences [q-bio], Killer Cells, Natural, Biochemistry, rab GTP-Binding Proteins, [SDV.IMM]Life Sciences [q-bio]/Immunology, Lysosomes, 030215 immunology, T-Lymphocytes, Cytotoxic
Abstract

International audience; 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.

Published
2007

7. Multifocal structure of the T cell - dendritic cell synapse

Author

Alain Schmitt, Clotilde Randriamampita, Cédric Brossard, Alain Trautmann, Graça Raposo, Maryse Romao, Vincent Feuillet, [Institut Cochin] Departement Infection, immunité, inflammation, Institut Cochin (IC UM3 (UMR 8104 / U1016)), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
CD3 Complex, T cell, T-Lymphocytes, Immunology, Fluorescent Antibody Technique, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Biology, Immunofluorescence, law.invention, Synapse, 03 medical and health sciences, Mice, 0302 clinical medicine, law, medicine, Immunology and Allergy, Animals, Cytoskeleton, Antigen-presenting cell, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, 0303 health sciences, medicine.diagnostic_test, Dendritic cell, Dendritic Cells, Intercellular Adhesion Molecule-1, Immunological Synapses, Lymphocyte Function-Associated Antigen-1, Cell biology, Mice, Inbred C57BL, Microscopy, Electron, medicine.anatomical_structure, Synapses, [SDV.IMM]Life Sciences [q-bio]/Immunology, Electron microscope, 030215 immunology
Abstract

The structure of immunological synapses formed between murine naive T cells and mature dendritic cells has been subjected to a quantitative analysis. Immunofluorescence images of synapses formed in the absence of antigen show a diffuse synaptic accumulation of CD3 and LFA-1. In electron microscopy, these antigen-free synapses present a number of tight appositions (cleft size approximately 15 nm), all along the synapse. These tight appositions cover a significantly larger surface fraction of antigen-dependent synapses. In immunofluorescence, antigen-dependent synapses show multiple patches of CD3 and LFA-1 with a variable overlap. A similar distribution is observed for PKCtheta and talin. A concentric organization characteristic of prototypical synapses is rarely observed, even when dendritic cells are paralyzed by cytoskeletal poisons. In T-DC synapses, the interaction surface is composed of several tens of submicronic contact spots, with no large-scale segregation of CD3 and LFA-1. As a comparison, in T-B synapses, a central cluster of CD3 is frequently observed by immunofluorescence, and electron microscopy reveals a central tight apposition. Our data show that it is inappropriate to consider the concentric structure as a "mature synapse" and multifocal structures as immature.

Published
2005

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