title: Differential involvement of p38 MAP kinase pathway and Bax translocation in the mitochondria-mediated cell death in TCR- and dexamethasone-stimulated thymocytes.
abstract: Mitochondria play a central role in many apoptotic reactions. Although mitochondrial apoptotic changes and caspase activation have been demonstrated in the apoptotic thymocytes, cell death signal through mitochondria in TCR-stimulated thymocytes has not been fully understood. In this study, we show that TCR stimulation induced disruption of mitochondrial transmembrane potential (Delta Psi(m)), the cytochrome c release from mitochondira, capase-3 activation, and the cell death of thymocytes. Bongkrekic acid, an inhibitor of Delta Psi(m) disruption, blocked the cytochrome c release from mitochondria and the following caspase-3-mediated cell death. Furthermore, a pro-apoptotic Bcl-2 family protein, Bax, but not Bad or Bid, was translocated from cytosol to mitochondria in TCR-stimulated thymocytes. This translocation and the following apoptotic changes were inhibited by SB203580, a p38 kinase inhibitor, in a specific manner. These results suggest that activated p38 kinase pathway by TCR stimulation induces translocation of Bax to mitochondria, causing Delta Psi(m) disruption, and the release of cytochrome c, which finally induces caspase-3-mediated apoptosis in thymocytes.
authors.affiliation: Department of Immunology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yoshino
authors.forename: H
authors.initials: H
authors.lastname: Kishi
authors.forename: T
authors.initials: T
authors.lastname: Nagata
authors.forename: K
authors.initials: K
authors.lastname: Tsukada
authors.forename: S
authors.initials: S
authors.lastname: Saito
authors.forename: A
authors.initials: A
authors.lastname: Muraguchi
mesh_terms: D000818:Animals; D017209:Apoptosis; D001865:Bongkrekic Acid / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology*; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: C494827:Bax protein, mouse; D003574:Cytochrome c Group; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell; D051028:bcl-2-Associated X Protein; D001865:Bongkrekic Acid; D003907:Dexamethasone; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases