title: Trypanosoma cruzi posttranscriptionally up-regulates and exploits cellular FLIP for inhibition of death-inducing signal.
abstract: Intracellular persistence of the protozoan parasite, Trypanosoma cruzi, is an aggravating cause of Chagas' disease, involving that the protozoan infection specifically inhibits death receptor-mediated apoptosis of host cells. Here we demonstrate that the parasite dramatically up-regulates cellular FLICE inhibitory protein (c-FLIP), the only known mammalian inhibitor specific for death receptor signaling, in infected cells by an unusual, posttranscriptional stabilization of the short-lived protein. We also show that c-FLIP is accumulated in T. cruzi-infected mouse heart muscle cells in vivo. Stimulation of death receptor Fas in infected cells induces recruitment of c-FLIP to block the procaspase-8 activation at the most upstream caspase cascade. c-FLIP knock-down with a small interfering RNA significantly restores Fas-mediated apoptosis in infected cells. Taken together, our findings indicate that T. cruzi posttranscriptionally up-regulates and exploits host c-FLIP for the inhibition of death-inducing signal, a mechanism that may allow parasites to persist in host cells.
authors.affiliation: Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Muneaki
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Junko
authors.initials: J
authors.lastname: Nakajima-Shimada
authors.forename: Takashi
authors.initials: T
authors.lastname: Aoki
mesh_terms: D000818:Animals; D017209:Apoptosis; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D005260:Female; D006321:Heart / Q000469:parasitology; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics; D014349:Trypanosoma cruzi / Q000502:physiology*; D015854:Up-Regulation; D019014:fas Receptor / Q000378:metabolism
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; C506387:Cflar protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D019014:fas Receptor; C505530:CASP8 protein, human; C505526:Casp8 protein, mouse; D053181:Caspase 8; D020169:Caspases