NF-kappaB inhibition reveals differential mechanisms of TNF versus TRAIL-induced apoptosis upstream or at the level of caspase-8 activation independent of cIAP2

Tobias Longin Haas, Philip Diessenbacher, Mike Hupe, Martin R. Sprick, Andreas Kerstan, Peter Geserick, Tina Wachter, Manfred Neumann, Henning Walczak, John Silke, Martin Leverkus

Risultato della ricerca: Contributo in rivistaArticolo in rivista

53 Citazioni (Scopus)

Abstract

Death ligands not only activate a death program but also regulate inflammatory signalling pathways, for example, through NF-κB induction. Although tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and TNF both activate NF-κB in human keratinocytes, only TRAIL potently induces apoptosis. However, when induction of NF-κB was inhibited with a kinase dead IKK2 mutant (IKK2-KD), TNF- but not TRAIL-induced apoptosis was dramatically enhanced. Acquired susceptibility to TNF-induced apoptosis was due to increased caspase-8 activation. To investigate the mechanism of resistance of HaCaT keratinocytes to TNF-induced apoptosis, we analyzed a panel of NF-κB-regulated effector molecules. Interestingly, the inhibitor of apoptosis protein (IAP) family member cIAP2, but not cIAP1, X-linked inhibitor of apoptosis, TNF receptor-associated factor (TRAF)-1, or TRAF2, was downregulated in sensitive but not in resistant HaCaT keratinocytes. Surprisingly, however, stable inducible expression of cIAP2 was not sufficient to render IKK2-KD-sensitized keratinocytes resistant to TNF, and reduction of cIAP2 alone did not increase the sensitivity of HaCaT keratinocytes to TNF. In conclusion, we demonstrate that inhibition of NF-κB dramatically sensitizes human keratinocytes to TNF- but not to TRAIL-induced apoptosis and that this sensitization for TNF was largely independent of cIAP2. Our data thus clearly exclude the candidates proposed to date to confer TNF apoptosis resistance and suggest the function of an unanticipated effector of NF-κB critical for the survival of HaCaT keratinocytes upstream or at the level of caspase-8 activation. © 2007 The Society for Investigative Dermatology.
Lingua originaleEnglish
pagine (da-a)1134-1147
Numero di pagine14
RivistaJournal of Investigative Dermatology
Volume128
DOI
Stato di pubblicazionePubblicato - 2008

Keywords

  • 2708
  • Medicine (all)

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