title: A role for p21ras/MAP kinase in TCR-mediated activation of LFA-1.
abstract: LFA-1 is a beta2 integrin that plays well-characterized roles in adhesion of T lymphocytes to APC, T cell-mediated cytolysis, and leukocyte-endothelial cell interactions. Although it is clear that LFA-1 must undergo affinity or avidity changes to bind its cellular ligand ICAM-1, the intracellular signaling pathways involved are not well characterized. Here, we show that the Ras-mitogen-activated protein kinase (MAPK) signaling pathway is also involved in TCR-activated LFA-1 adhesion. Expression of a dominant negative form of p21ras in a thymocyte cell line inhibits, while constitutively active p21ras both enhances and sustains, subsequent TCR-triggered adhesion to isolated ICAM-1. However, the Ras/MAPK pathway alone is not sufficient for activating T cell LFA-1, as inhibition of both downstream MAPK/extracellular regulated kinase kinase (MEK) activity and phosphatidylinositol 3-kinase activity is required for complete inhibition of adhesion.
authors.affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA. orourke@scripps.edu
authors.forename: A M
authors.initials: AM
authors.lastname: O'Rourke
authors.forename: H
authors.initials: H
authors.lastname: Shao
authors.forename: J
authors.initials: J
authors.lastname: Kaye
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D004789:Enzyme Activation / Q000276:immunology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D048728:MAP Kinase Kinase Kinase 1; D051379:Mice; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D016169:Lymphocyte Function-Associated Antigen-1; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011948:Receptors, Antigen, T-Cell; D018799:Intercellular Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; D048728:MAP Kinase Kinase Kinase 1; C482578:Map3k1 protein, mouse; D016283:Proto-Oncogene Proteins p21(ras)