title: p38 mitogen-activated protein kinase mediates the Fas-induced mitochondrial death pathway in CD8+ T cells.
abstract: The p38 mitogen-activated protein kinase (MAPK) signaling pathway can be activated by a variety of stress stimuli such as UV radiation and osmotic stress. The regulation and role of this pathway in death receptor-induced apoptosis remain unclear and may depend on the specific death receptor and cell type. Here we show that binding of Fas ligand to Fas activates p38 MAPK in CD8+ T cells and that activation of this pathway is required for Fas-mediated CD8+ T-cell death. Active p38 MAPK phosphorylates Bcl-xL and Bcl-2 and prevents the accumulation of these antiapoptotic molecules within the mitochondria. Consequently, a loss of mitochondrial membrane potential and the release of cytochrome c lead to the activation of caspase 9 and, subsequently, caspase 3. Therefore, the activation of p38 MAPK is a critical link between Fas and the mitochondrial death pathway and is required for the Fas-induced apoptosis of CD8+ T cells.
authors.affiliation: Department of Medicine/Immunobiology Program, Given Medical Building D305, University of Vermont, Burlington, VT 05405, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Farley
authors.forename: Gustavo
authors.initials: G
authors.lastname: Pedraza-Alva
authors.forename: Diego
authors.initials: D
authors.lastname: Serrano-Gomez
authors.forename: Viswas
authors.initials: V
authors.lastname: Nagaleekar
authors.forename: Alexander
authors.initials: A
authors.lastname: Aronshtam
authors.forename: Troy
authors.initials: T
authors.lastname: Krahl
authors.forename: Tina
authors.initials: T
authors.lastname: Thornton
authors.forename: Mercedes
authors.initials: M
authors.lastname: Rincón
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D015398:Signal Transduction; D048069:Tumor Necrosis Factors / Q000378:metabolism / Q000494:pharmacology; D051020:bcl-X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D048069:Tumor Necrosis Factors; D051020:bcl-X Protein; D019014:fas Receptor; D045304:Cytochromes c; D048051:p38 Mitogen-Activated Protein Kinases; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases