The C-terminal Domain of the Long Form of Cellular FLICE-inhibitory Protein (c-FLIPL) Inhibits the Interaction of the Caspase 8 Prodomain with the Receptor-interacting Protein 1 (RIP1) Death Domain and Regulates Caspase 8-dependent Nuclear Factor κB (NF-κB) Activation

• Published in: The Journal of biological chemistry 2014-02, Vol.289 (7), p.3876-3887
• Main Authors: Matsuda, Iyo, Matsuo, Kentaro, Matsushita, Yuka, Haruna, Yasushi, Niwa, Masamitsu, Kataoka, Takao
• Format: Article
• Language: English
• Subjects: CASP8 and FADD-Like Apoptosis Regulating Protein - genetics; CASP8 and FADD-Like Apoptosis Regulating Protein - metabolism; Caspase; Caspase 8 - genetics; Caspase 8 - metabolism; Death Domain; Fas; HEK293 Cells; Humans; NF-kappa B - genetics; NF-kappa B - metabolism; NF-κB; Nuclear Pore Complex Proteins - genetics; Nuclear Pore Complex Proteins - metabolism; Protease Inhibitors - pharmacology; Protein Structure, Tertiary; RIP; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Signal Transduction; TNF Receptor-Associated Factor 2 - genetics; TNF Receptor-Associated Factor 2 - metabolism; U937 Cells
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.506485

Caspase 8 plays an essential role in the regulation of apoptotic and non-apoptotic signaling pathways. The long form of cellular FLICE-inhibitory protein (c-FLIPL) has been shown previously to regulate caspase 8-dependent nuclear factor κB (NF-κB) activation by receptor-interacting protein 1 (RIP1) and TNF receptor-associated factor 2 (TRAF2). In this study, the molecular mechanism by which c-FLIPL regulates caspase 8-dependent NF-κB activation was further explored in the human embryonic kidney cell line HEK 293 and variant cells barely expressing caspase 8. The caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone greatly diminished caspase 8-dependent NF-κB activation induced by Fas ligand (FasL) when c-FLIPL, but not its N-terminal fragment c-FLIP(p43), was expressed. The prodomain of caspase 8 was found to interact with the RIP1 death domain and to be sufficient to mediate NF-κB activation induced by FasL or c-FLIP(p43). The interaction of the RIP1 death domain with caspase 8 was inhibited by c-FLIPL but not c-FLIP(p43). Thus, these results reveal that the C-terminal domain of c-FLIPL specifically inhibits the interaction of the caspase 8 prodomain with the RIP1 death domain and, thereby, regulates caspase 8-dependent NF-κB activation. Caspase 8 and c-FLIPL regulate NF-κB activation via RIP1. The caspase 8 prodomain mediates NF-κB activation, and its interaction with the RIP1 death domain is inhibited by c-FLIPL but not c-FLIP(p43). The C-terminal domain of c-FLIPL inhibits the interaction of caspase 8 with the RIP1 death domain and caspase 8-dependent NF-κB activation. This study provides a novel molecular mechanism by which c-FLIPL cleavage is required for NF-κB activation.