title: TNF receptor-associated factor-1 (TRAF1) negatively regulates Toll/IL-1 receptor domain-containing adaptor inducing IFN-beta (TRIF)-mediated signaling.
abstract: Toll-like receptor 3 (TLR3) plays an important role in antiviral responses through recognizing viral double-stranded RNA produced during viral infection and mediating induction of type I IFN. TRIF is a Toll/IL-1 receptor (TIR) domain-containing adaptor protein that is associated with TLR3 and critically involved in TLR3-mediated signaling. In yeast two-hybrid screens, we identified TNF receptor-associated factor (TRAF)1 as a TRIF-interacting protein. The TRAF-C domain of TRAF1 and the TIR domain of TRIF were responsible for their interaction. Overexpression of TRAF1 inhibited TRIF- and TLR3-mediated activation of NF-kappaB, IFN-stimulated response element and the IFN-beta promoter. Overexpression of TRIF caused caspase-dependent cleavage of TRAF1. The cleaved N-terminal but not C-terminal fragment of TRAF1 was responsible for inhibiting TRIF signaling. Mutation of the caspase cleavage site of TRAF1 or addition of the caspase inhibitor crmA inhibited TRAF1 cleavage and abolished the ability of TRAF1 to inhibit TRIF signaling, suggesting that TRIF-induced cleavage of TRAF1 is required for its inhibition of TRIF signaling. Our findings provide a novel mechanism for negative regulation of TRIF-mediated signaling.
authors.affiliation: College of Life Sciences, Peking University, Beijing, China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Su
authors.forename: Su
authors.initials: S
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Meng
authors.forename: Wanqiang
authors.initials: W
authors.lastname: Qian
authors.forename: Wei
authors.initials: W
authors.lastname: Xie
authors.forename: Danying
authors.initials: D
authors.lastname: Chen
authors.forename: Zhonghe
authors.initials: Z
authors.lastname: Zhai
authors.forename: Hong-Bing
authors.initials: HB
authors.lastname: Shu
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D016899:Interferon-beta / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism; D017472:Receptors, Interleukin-1 / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology*; D047990:TNF Receptor-Associated Factor 1 / Q000276:immunology / Q000378:metabolism*; D051196:Toll-Like Receptor 3 / Q000276:immunology / Q000378:metabolism; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D016328:NF-kappa B; D017472:Receptors, Interleukin-1; C470409:TICAM1 protein, human; D047990:TNF Receptor-Associated Factor 1; D051196:Toll-Like Receptor 3; D016899:Interferon-beta