title: CD28-stimulated ERK2 phosphorylation is required for polarization of the microtubule organizing center and granules in YTS NK cells.
abstract: Activation of natural killer (NK) cell cytotoxicity requires adhesion and formation of a conjugate with a susceptible target cell, followed by actin polymerization, and polarization of the microtubule organizing center (MTOC) and cytolytic granules to the NK cell immune synapse. Here, by using the YTS NK cell line as a model, CD28 is shown to be an activating receptor. It signals cytotoxicity in a process dependent on phosphoinositide-3 kinase activation, leading to sustained extracellular signal-regulated kinase 2 (ERK2) phosphorylation. ERK and phospho-ERK localize to microtubule filaments. Neither conjugation with targets nor actin polymerization is affected by blocking ERK2 activation. However, both polarization of the MTOC and cytolytic granules to the synaptic region and NK cell cytotoxicity are strongly reduced by blocking ERK2 activation. A role for the CD28/CD80 interaction in cytotoxicity of human peripheral NK cells also was established. By contrast, lymphocyte function-associated antigen 1 (LFA-1) ligation transduces only a transient ERK2 activation and fails to induce killing in YTS cells. Thus, in YTS cells, a CD28 signal is used to polarize the MTOC and cytolytic granules to the NK cell immune synapse by stimulating sustained ERK2 activation.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138.
authors.forename: David S J
authors.initials: DSJ
authors.lastname: Allan
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138.
authors.forename: Konrad
authors.initials: K
authors.lastname: Krzewski
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138.
authors.forename: Baoxue
authors.initials: B
authors.lastname: Ge
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138.
authors.forename: Hernan
authors.initials: H
authors.lastname: Kopcow
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138 jlstrom@fas.harvard.edu.
authors.forename: Jack L
authors.initials: JL
authors.lastname: Strominger
mesh_terms: D017209:Apoptosis; D018821:CD18 Antigens / Q000378:metabolism; D018106:CD28 Antigens / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity; D004789:Enzyme Activation; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology* / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D022101:Microtubule-Organizing Center / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D010766:Phosphorylation; D013997:Time Factors
chemical_list: D018821:CD18 Antigens; D018106:CD28 Antigens; D016169:Lymphocyte Function-Associated Antigen-1; D019950:Mitogen-Activated Protein Kinase 1