title: MAPK/ERK signaling in activated T cells inhibits CD95/Fas-mediated apoptosis downstream of DISC assembly.
abstract: When T cells are activated, the expression of the CD95 ligand is elevated, with the purpose of inducing apoptosis in target cells and to later eliminate the activated T cells. We have shown previously that mitogen-activated protein kinase (MAPK or ERK) signaling suppresses CD95-mediated apoptosis in different cellular systems. In this study we examined whether MAPK signaling controls the persistence and CD95-mediated termination of an immune response in activated T cells. Our results show that activation of Jurkat T cells through the T cell receptor immediately suppresses CD95-mediated apoptosis, and that this suppression is mediated by MAPK activation. During the phase of elevated MAPK activity, the activation of caspase-8 and Bid is inhibited, whereas the assembly of a functional death-inducing signaling complex (DISC) is not affected. These results explain the resistance to CD95 responses observed during the early phase of T cell activation and suggest that MAPK-activation deflects DISC signaling from activating caspase-8 and Bid. The physiological relevance of the results was confirmed in activated primary peripheral T cells, in which inhibition of MAPK signaling markedly sensitized the cells to CD95-mediated apoptosis.
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Abo Akademi University, PO Box 123, FIN-20521 Turku, Finland.
authors.forename: T H
authors.initials: TH
authors.lastname: Holmström
authors.forename: I
authors.initials: I
authors.lastname: Schmitz
authors.forename: T S
authors.initials: TS
authors.lastname: Söderström
authors.forename: M
authors.initials: M
authors.lastname: Poukkula
authors.forename: V L
authors.initials: VL
authors.lastname: Johnson
authors.forename: S C
authors.initials: SC
authors.lastname: Chow
authors.forename: P H
authors.initials: PH
authors.lastname: Krammer
authors.forename: J E
authors.initials: JE
authors.lastname: Eriksson
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D017252:CD3 Complex / Q000276:immunology; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D053222:Fas Ligand Protein; D005455:Fluorescent Antibody Technique; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016853:Muromonab-CD3 / Q000276:immunology / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051025:bcl-Associated Death Protein; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism*
chemical_list: C494819:BAD protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D017252:CD3 Complex; C506386:CFLAR protein, human; D002352:Carrier Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D016853:Muromonab-CD3; D019253:Proto-Oncogene Proteins c-bcl-2; D051025:bcl-Associated Death Protein; D019014:fas Receptor; D020928:Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D013755:Tetradecanoylphorbol Acetate