title: Trichothecene mycotoxins trigger a ribotoxic stress response that activates c-Jun N-terminal kinase and p38 mitogen-activated protein kinase and induces apoptosis.
abstract: The trichothecene family of mycotoxins inhibit protein synthesis by binding to the ribosomal peptidyltransferase site. Inhibitors of the peptidyltransferase reaction (e.g. anisomycin) can trigger a ribotoxic stress response that activates c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinases, components of a signaling cascade that regulates cell survival in response to stress. We have found that selected trichothecenes strongly activate JNK/p38 kinases and induce rapid apoptosis in Jurkat T cells. Although the ability of individual trichothecenes to inhibit protein synthesis and activate JNK/p38 kinases are dissociable, both effects contribute to the induction of apoptosis. Among trichothecenes that strongly activate JNK/p38 kinases, induction of apoptosis increases linearly with inhibition of protein synthesis. Among trichothecenes that strongly inhibit protein synthesis, induction of apoptosis increases linearly with activation of JNK/p38 kinases. Trichothecenes that inhibit protein synthesis without activating JNK/p38 kinases inhibit the function (i.e. activation of JNK/p38 kinases and induction of apoptosis) of apoptotic trichothecenes and anisomycin. Harringtonine, a structurally unrelated protein synthesis inhibitor that competes with trichothecenes (and anisomycin) for ribosome binding, also inhibits the activation of JNK/p38 kinases and induction of apoptosis by trichothecenes and anisomycin. Taken together, these results implicate the peptidyltransferase site as a regulator of both JNK/p38 kinase activation and apoptosis.
mesh_terms: D000841:Anisomycin / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D053938:DNA Fragmentation; D004640:Emetine / Q000494:pharmacology; D004789:Enzyme Activation; D006248:Harringtonines / Q000494:pharmacology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells; D007700:Kinetics; D020928:Mitogen-Activated Protein Kinases; D018384:Oxidative Stress / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012270:Ribosomes / Q000187:drug effects* / Q000201:enzymology; D013605:T-2 Toxin / Q000494:pharmacology; D014255:Trichothecenes / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases