title: FADD deficiency sensitises Jurkat T cells to TNF-alpha-dependent necrosis during activation-induced cell death.
abstract: Activation-induced cell death (AICD) in activated T lymphocytes is largely mediated by Fas/Fas ligand (FasL) interaction. The cytoplasmic adaptor molecule Fas-associated death domain protein (FADD) plays an essential role in the apoptotic signalling of the Fas death pathway. In the present study, we observed that FADD deficient (FADD(-/-)) Jurkat T cells undergo AICD to a similar extent as wild-type cells. AICD in wild-type Jurkat T cells is via apoptosis, whereas it is non-apoptotic in FADD(-/-) cells. The latter took up propidium iodide, exhibit a loss in mitochondrial membrane potential and have no detectable cleavage products of caspase-8 or -3 activation, suggesting that these cells die by necrosis. Wild-type Jurkat T cells undergo apoptosis when incubated with recombinant FasL and Trail but not with TNF-alpha. In contrast, FADD(-/-) Jurkat T cells are resistant to FasL and Trail but die of necrosis when incubated with TNF-alpha. We showed that neutralising anti-TNF-alpha blocked AICD as well as TNF-alpha-induced necrosis in FADD(-/-) Jurkat T cells. Furthermore, down regulating the receptor interacting protein, RIP, with geldanamycin treatment, which is essential for TNF-alpha signalling, markedly inhibited AICD in FADD(-/-) Jurkat T cells. In addition, caspase-8-deficient Jurkat T cells are resistant to Fas- and TNF-alpha-induced cell death. Taken together, our results suggest that a deficiency in FADD and not caspase-8 or the inhibition of the Fas signalling pathway sensitises Jurkat T cells to TNF-alpha-dependent necrosis during AICD.
authors.affiliation: Medical Research Council Toxicology Unit, University of Leicester, Leicester LE1 9HN, United Kingdom.
authors.forename: C P
authors.initials: CP
authors.lastname: Lawrence
authors.forename: S C
authors.initials: SC
authors.lastname: Chow
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency* / Q000235:genetics; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000494:pharmacology; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; D006801:Humans; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000494:pharmacology; D009336:Necrosis; D013601:T-Lymphocytes / Q000187:drug effects* / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D048069:Tumor Necrosis Factors / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C505533:FADD protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D048069:Tumor Necrosis Factors; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases