title: Collagen type I-mediated activation of ERK/MAP Kinase is dependent on Ras, Raf-1 and protein phosphatase 2A in Jurkat T cells.
abstract: Growing evidence indicates that interactions of T cells with extracellular matrix through beta1 integrins are important for the regulation of T cell-mediated immune responses and diseases. In this regard, we have recently demonstrated that collagen I (Coll I) through alpha2beta1 integrin inhibited Fas-induced apoptosis of T cells by activating a protein phosphatase 2A (PP2A)-dependent ERK/MAP Kinase pathway. As survival of T cells is critical for their functions, we further investigated the mechanisms underlying the activation of this pathway. Inhibition studies demonstrated that Coll I activates the ERK/MAP Kinase pathway in Jurkat T cells through the activation of Ras and Raf-1. Activation of PP2A was not necessary for the binding of Coll I to Jurkat T cells, but is required for the activation of Raf-1. In accordance, activation of Ras, Raf-1 and PP2A were also required for the ability of Coll I to protect Jurkat T cells from Fas-induced apoptosis. In contrast and despite its capacity to activate Ras, fibronectin (Fbn) failed to activate PP2A and Raf-1. These results might explain, at least in part, the weak ability of Fbn to activate ERK in T cells, supporting thus the differential signaling of beta1 integrin members in these cells. This study provides novel insights into the mechanisms by which beta1 integrins activate the ERK/MAP Kinase pathway in T cells, and is the first report to provide a role for PP2A in integrin-mediated ERK/MAP Kinase activation.
authors.affiliation: Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Pavillon CHUL, and Faculté de Médecine, Université Laval, 2705, Blvd. Laurier, Local T1-49, Que., Canada G1V 4G2.
authors.forename: Nizar
authors.initials: N
authors.lastname: Chetoui
authors.forename: Steve
authors.initials: S
authors.lastname: Gendron
authors.forename: Estelle
authors.initials: E
authors.lastname: Chamoux
authors.forename: Fawzi
authors.initials: F
authors.lastname: Aoudjit
mesh_terms: D024042:Collagen Type I / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism* / Q000494:pharmacology; D019169:Jurkat Cells; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000502:physiology*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D019908:Proto-Oncogene Proteins c-raf / Q000037:antagonists & inhibitors / Q000502:physiology*; D016283:Proto-Oncogene Proteins p21(ras) / Q000037:antagonists & inhibitors / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology*
chemical_list: D024042:Collagen Type I; D019012:Integrin beta1; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D016283:Proto-Oncogene Proteins p21(ras)