title: A new domain in the Toll/IL-1R domain-containing adaptor inducing interferon-β factor protein amino terminus is important for tumor necrosis factor-α receptor-associated factor 3 association, protein stabilization and interferon signaling.
abstract: Toll/IL-1R domain-containing adaptor inducing interferon-β (IFN-β) factor (TRIF) is a key adaptor for Toll-like receptor (TLR) 3 and TLR4 signaling. Using a novel cDNA isolate encoding a TRIF protein with a 21-residue deletion (Δ160-181) from its amino-terminal half, we investigated the impact of this deletion on TRIF functions. Transfection studies consistently showed higher expression levels of the (Δ160-181) TRIF compared to wild-type (wt) TRIF, an effect unrelated to apoptosis, cell lines or plasmid amplification. Colocalization of wt and (Δ160-181) TRIF proteins led to a dramatic reduction of their respective expressions, suggesting that wt/(Δ160-181) TRIF heterocomplexes are targeted for degradation. We demonstrated that wt TRIF associates with tumor necrosis factor-α receptor-associated factor 3 (TRAF3) better than (Δ160-181) TRIF, culminating in its greater ubiquitination and proteolysis. This explains, in part, the differential expression levels of the two TRIF proteins. Despite higher expression levels in transfected cells, (Δ160-181) TRIF inefficiently transactivated the IFN pathway, whereas the nuclear factor-κB (NF-κB) pathway activation remained similar to that by wt TRIF. In coexpression studies, (Δ160-181) TRIF marginally contributed to the IFN pathway activation, but still enhanced NF-κB signaling with wt TRIF. Therefore, this 21 amino acid sequence is crucial for TRAF3 association, modulation of TRIF stability and activation of the IFN pathway.
authors.affiliation: Metabolism Branch, Center for Cancer Research, National Institutes of Health, Bethesda, Md., USA.
authors.forename: Vinh-Phuc
authors.initials: VP
authors.lastname: Nguyen
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Michael N
authors.initials: MN
authors.lastname: Petrus
authors.forename: Carolyn K
authors.initials: CK
authors.lastname: Goldman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kruhlak
authors.forename: Richard N
authors.initials: RN
authors.lastname: Bamford
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Waldmann
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007372:Interferons / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D055550:Protein Stability; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport; D059748:Proteolysis; D017384:Sequence Deletion / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D048008:TNF Receptor-Associated Factor 3 / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D016328:NF-kappa B; C470409:TICAM1 protein, human; D048008:TNF Receptor-Associated Factor 3; D051197:Toll-Like Receptor 4; D007372:Interferons