Role of oxidative damage and IL-1 beta-converting enzyme-like proteases in Fas-based cytotoxicity exerted by effector T cells.
The implication of oxidative damage and/or intact mitochondrial function in physiological Fas-based cytotoxicity has been tested using the cytolytic hybridoma d11S and the CD8(+) CTL clone KB5.C20, previously stimulated to express Fas ligand (FasL) on their surface, as effectors and U937 or U937-rho0 cells (depleted of mitochondrial DNA) as targets. Immobilized anti-Fas mAb, which induced death of U937 cells, inhibited the growth of U937-rho0 cells but without inducing cell death. By contrast, FasL-expressing effectors readily killed both targets, with induction of DNA fragmentation, in 20 h assays. These results demonstrate the lack of involvement of mitochondrial-derived free radicals and/or intact mitochondrial function in physiological Fas-based cytotoxicity. Supplementation of Fas-sensitive cells (Jurkat, U937, L1210Fas) with a polyunsaturated fatty acid, which induces cell death through the generation of lipid free radicals, resulted in the potentiation of Fas-based cytotoxicity. This potentiating effect, but not Fas-based cytotoxicity itself, was eliminated by the physiological antioxidant vitamin E. On the other hand, the IL-1beta-converting enzyme (ICE)-like protease tetrapeptide inhibitor Ac-YVAD-cmk partially inhibited Fas-based cytotoxicity, while the specific inhibitor of CPP32/Yama Ac-DEVD-CHO was a much more effective inhibitor of Fas-induced apoptosis. It was concluded that Fas-induced cytotoxicity was clearly dependent on ICE-like protease activation, and especially on that of CPP32 in Fas-sensitive cells, including mitochondrial DNA-depleted ones.
Anel
A
A
Departamento de Bioquimica y Biologia Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain.
Gamen
S
S
Alava
M A
MA
Schmitt-Verhulst
A M
AM
Piñeiro
A
A
Naval
J
J
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D020170:Caspase 1; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000502:physiology*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D007739:L Cells; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000276:immunology*; D011480:Protease Inhibitors / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000187:drug effects / Q000494:pharmacology*
D005231:Fatty Acids, Unsaturated; D011480:Protease Inhibitors; D019014:fas Receptor; D003546:Cysteine Endopeptidases; D020170:Caspase 1