dsRNA induces apoptosis through an atypical death complex associating TLR3 to caspase-8.
Fiche publication
Date publication
septembre 2012
Auteurs
Membres identifiés du Cancéropôle Est :
Dr MICHEAU Olivier
Tous les auteurs :
Estornes Y, Toscano F, Virard F, Jacquemin G, Pierrot A, Vanbervliet B, Bonnin M, Lalaoui N, Mercier-Gouy P, Pacheco Y, Salaun B, Renno T, Micheau O, Lebecque S
Lien Pubmed
Résumé
Toll-like receptor 3 (TLR3) is a pattern-recognition receptor known to initiate an innate immune response when stimulated by double-stranded RNA (dsRNA). Components of TLR3 signaling, including TIR domain-containing adapter inducing IFN-alpha (TRIF), have been demonstrated to contribute to dsRNA-induced cell death through caspase-8 and receptor interacting protein (RIP)1 in various human cancer cells. We provide here a detailed analysis of the caspase-8 activating machinery triggered in response to Poly(I:C) dsRNA. Engagement of TLR3 by dsRNA in both type I and type II lung cancer cells induces the formation of an atypical caspase-8-containing complex that is devoid of classical death receptors of the TNFR superfamily, but instead is physically associated to TLR3. The recruitment of caspase-8 to TLR3 requires RIP1, and is negatively modulated by cellular inhibitor of apoptosis protein (cIAP)2-TNF receptor-associated factor (TRAF)2-TNFR-associated death domain (TRADD) ubiquitin ligase complex, which regulates RIP1 ubiquitination. Intriguingly, unlike Fas- or TRAILR-dependent death signaling, caspase-8 recruitment and activation within the TLR3 death-signaling complex appears not to be stringently dependent on Fas-associated with death domain (FADD). Our findings uncover a novel aspect of the molecular mechanisms involved during apoptosis induced by the innate immune receptor TLR3 in cancer cells.
Référence
Cell Death Differ. 2012 Sep;19(9):1482-94