title: In mouse embryonic fibroblasts, neither caspase-8 nor cellular FLICE-inhibitory protein (FLIP) is necessary for TNF to activate NF-κB, but caspase-8 is required for TNF to cause cell death, and induction of FLIP by NF-κB is required to prevent it.
abstract: Binding of TNF to TNF receptor-1 can give a pro-survival signal through activation of p65/RelA NF-κB, but also signals cell death. To determine the roles of FLICE-inhibitory protein (FLIP) and caspase-8 in TNF-induced activation of NF-κB and apoptosis, we used mouse embryonic fibroblasts derived from FLIP and caspase-8 gene-deleted mice, and treated them with TNF and a smac-mimetic compound that causes degradation of cellular inhibitor of apoptosis proteins (cIAPs). In cells treated with smac mimetic, TNF and Fas Ligand caused wild-type and FLIP(-/-) MEFs to die, whereas caspase-8(-/-) MEFs survived, indicating that caspase-8 is necessary for death of MEFs triggered by these ligands when IAPs are degraded. By contrast, neither caspase-8 nor FLIP was required for TNF to activate p65/RelA NF-κB, because IκB was degraded, p65 translocated to the nucleus, and an NF-κB reporter gene activated normally in caspase-8(-/-) or FLIP(-/-) MEFs. Reconstitution of FLIP(-/-) MEFs with the FLIP isoforms FLIP-L, FLIP-R, or FLIP-p43 protected these cells from dying when treated with TNF or FasL, whether or not cIAPs were depleted. These results show that in MEFs, caspase-8 is necessary for TNF- and FasL-induced death, and FLIP is needed to prevent it, but neither caspase-8 nor FLIP is required for TNF to activate NF-κB.
authors.affiliation: La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC 3086, Australia.
authors.forename: D M
authors.initials: DM
authors.lastname: Moujalled
authors.forename: W D
authors.initials: WD
authors.lastname: Cook
authors.forename: J M
authors.initials: JM
authors.lastname: Lluis
authors.forename: N R
authors.initials: NR
authors.lastname: Khan
authors.forename: A U
authors.initials: AU
authors.lastname: Ahmed
authors.forename: B A
authors.initials: BA
authors.lastname: Callus
authors.forename: D L
authors.initials: DL
authors.lastname: Vaux
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D015153:Blotting, Western; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D016328:NF-kappa B; D020033:Protein Isoforms; D014409:Tumor Necrosis Factor-alpha; D053181:Caspase 8
references.citation: Nat Rev Cancer. 2010 Aug;10(8):561-74
references.pmid: 20651737
references.citation: Immunity. 2000 Apr;12(4):419-29
references.pmid: 10795740
references.citation: Mol Cell Biol. 2004 Apr;24(7):2627-36
references.pmid: 15024054
references.citation: Cell Death Differ. 2008 Jan;15(1):213-5; author reply 215-6
references.pmid: 17992194
references.citation: Immunity. 1998 Aug;9(2):267-76
references.pmid: 9729047
references.citation: Mol Cell Biol. 2001 Aug;21(16):5299-305
references.pmid: 11463813
references.citation: Curr Biol. 2000 Jun 1;10(11):640-8
references.pmid: 10837247
references.citation: Oncogene. 2000 Sep 14;19(39):4451-60
references.pmid: 11002417
references.citation: EMBO J. 2002 Jul 15;21(14):3704-14
references.pmid: 12110583
references.citation: J Immunol. 1998 Oct 15;161(8):3936-42
references.pmid: 9780161
references.citation: Int J Biochem Cell Biol. 2010 Feb;42(2):210-3
references.pmid: 19932761
references.citation: J Biol Chem. 2009 Dec 18;284(51):35906-15
references.pmid: 19815541
references.citation: Science. 1996 Nov 1;274(5288):784-7
references.pmid: 8864119
references.citation: Blood. 2005 Sep 1;106(5):1581-9
references.pmid: 15905188
references.citation: Cell. 2007 Nov 16;131(4):682-93
references.pmid: 18022363
references.citation: Cell. 2009 Mar 20;136(6):1098-109
references.pmid: 19303852
references.citation: Cell. 2003 Jul 25;114(2):181-90
references.pmid: 12887920
references.citation: Immunity. 1997 Jun;6(6):751-63
references.pmid: 9208847
references.citation: J Immunol. 2005 Sep 15;175(6):3469-73
references.pmid: 16148088
references.citation: Genes Dev. 2003 Apr 1;17(7):883-95
references.pmid: 12654726
references.citation: Cell. 2004 Feb 20;116(4):491-7
references.pmid: 14980217
references.citation: J Mol Biol. 2008 Dec 12;384(2):313-23
references.pmid: 18835564
references.citation: Nat Immunol. 2007 Jun;8(6):592-600
references.pmid: 17468758
references.citation: J Biol Chem. 2003 Dec 19;278(51):51091-9
references.pmid: 14527959
references.citation: Immunity. 2000 Jun;12(6):633-42
references.pmid: 10894163
references.citation: J Biol Chem. 2008 Sep 5;283(36):24295-9
references.pmid: 18621737
references.citation: J Immunol. 2005 Apr 1;174(7):3999-4009
references.pmid: 15778357
references.citation: Genes Dev. 2000 Apr 1;14(7):854-62
references.pmid: 10766741
references.citation: Cell Death Differ. 2007 Feb;14(2):387-91
references.pmid: 17008913
references.citation: J Exp Med. 2006 May 15;203(5):1295-305
references.pmid: 16682493
references.citation: Proc Natl Acad Sci U S A. 2008 Nov 11;105(45):17463-8
references.pmid: 18981423
references.citation: J Biol Chem. 2000 Apr 14;275(15):10838-44
references.pmid: 10753878
references.citation: Cell Death Differ. 2002 Feb;9(2):138-44
references.pmid: 11840164
references.citation: Cell Death Differ. 2010 Mar;17(3):482-7
references.pmid: 19927158
references.citation: Cancer Res. 2009 Oct 1;69(19):7729-38
references.pmid: 19773432
references.citation: Nat Chem Biol. 2008 May;4(5):313-21
references.pmid: 18408713
references.citation: Cell. 2008 Feb 8;132(3):344-62
references.pmid: 18267068
references.citation: J Mol Biol. 2010 Feb 26;396(3):528-39
references.pmid: 20064526
references.citation: PLoS One. 2010 Jan 08;5(1):e8620
references.pmid: 20062539
references.citation: Gut. 2011 Feb;60(2):225-37
references.pmid: 20876774