Caspase inhibitors induce a switch from apoptotic to proinflammatory signaling in CD95-stimulated T lymphocytes.
CD95 is a major apoptosis receptor that induces caspase activation and programmed cell death in susceptible cells. CD95-induced apoptosis can be blocked by peptidic caspase inhibitors such as benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone or Ile-Glu-Thr-Asp-fluoromethyl ketone. Here we show that stimulation of CD95 in the presence of these inhibitors induces necrosis and expression of various proinflammatory cytokines in primary T lymphocytes, such as TNF-alpha, IFN-gamma and granulocyte/macrophage colony-stimulating factor. In the absence of caspase inhibition CD95 stimulation did not result in cytokine expression, indicating that this proinflammatory signaling pathway is suppressed by active caspases. Further analysis with A3.01 T cells revealed that the proinflammatory signaling activity of CD95 was mediated by MEK/ERK, p38 and NF-kappaB signaling pathways. These findings point to a pivotal role of caspases not only as mediators of apoptosis but also as enzymes that prevent proinflammatory signaling during CD95-induced apoptosis. Moreover, our findings may be useful for the development of novel pharmacological strategies.
Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität, Würzburg, Germany. scheller@vim.uni-wuerzburg.de
Carsten
C
Scheller
Sieghart
S
Sopper
Christina
C
Ehrhardt
Egbert
E
Flory
Peifeng
P
Chen
Eleni
E
Koutsilieri
Stephan
S
Ludwig
Volker
V
ter Meulen
Christian
C
Jassoy
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D015703:Antigens, CD / Q000187:drug effects / Q000502:physiology; D017209:Apoptosis / Q000187:drug effects*; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000494:pharmacology; D007249:Inflammation / Q000503:physiopathology*; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D016328:NF-kappa B / Q000502:physiology; D009336:Necrosis; D009570:Nitriles / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects / Q000502:physiology; D047888:Receptors, Tumor Necrosis Factor, Type I; D015398:Signal Transduction / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics; D019014:fas Receptor / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases
D000590:Amino Acid Chloromethyl Ketones; D015703:Antigens, CD; D002070:Butadienes; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D007093:Imidazoles; D016328:NF-kappa B; D009570:Nitriles; D009842:Oligopeptides; D011725:Pyridines; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; C113580:U 0126; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; C425644:isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D003546:Cysteine Endopeptidases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole