title: A signaling network stimulated by β2 integrin promotes the polarization of lytic granules in cytotoxic cells.
abstract: Cytotoxic lymphocytes kill target cells through the polarized release of the contents of intracellular perforin-containing granules. In natural killer (NK) cells, the binding of β2 integrin to members of the intercellular adhesion molecule family is sufficient to promote not only the adhesion of NK cells to target cells but also the polarization of intracellular lytic granules toward the target. We used NK cells in an experimental system designed to enable us to study the polarization of lytic granules in the absence of their release through degranulation, as well as β2 integrin signaling independently of inside-out signals from other receptors. Through a proteomics approach, we identified a signaling network centered on an integrin-linked kinase (ILK)-Pyk2-paxillin core that was required for granule and microtubule-organizing center (MTOC) polarization. The conserved Cdc42-Par6 signaling pathway, which controls cell polarity, was also activated by ILK and was required for granule polarization toward the target cell. A subset of the signaling components required for polarization contributed also to the convergence of granules on the MTOC. These results delineate two connected signaling networks that are stimulated upon β2 integrin engagement and control the polarization of the MTOC and associated lytic granules toward the site of contact with target cells to mediate cellular cytotoxicity.
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
authors.forename: Minggang
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: March
authors.affiliation: Mass Spectrometry and Proteomics Resource Laboratory, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: William S
authors.initials: WS
authors.lastname: Lane
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA. eLong@nih.gov.
authors.forename: Eric O
authors.initials: EO
authors.lastname: Long
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000704:Analysis of Variance; D015153:Blotting, Western; D018821:CD18 Antigens / Q000378:metabolism*; D016764:Cell Polarity / Q000276:immunology / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D003594:Cytoplasmic Granules / Q000276:immunology*; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D018613:Microscopy, Confocal; D022101:Microtubule-Organizing Center / Q000502:physiology; D009930:Organic Chemicals; D051419:Paxillin / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D053719:Tandem Mass Spectrometry; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D000099200:Scaffold Protein ILK
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018821:CD18 Antigens; D051418:Focal Adhesion Kinase 2; D009930:Organic Chemicals; D051419:Paxillin; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D020764:cdc42 GTP-Binding Protein; D000099200:Scaffold Protein ILK; C499657:PARD6A protein, human; C451241:PKH67