Bruton's tyrosine kinase phosphorylates Toll-like receptor 3 to initiate antiviral response

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 109; no. 15; pp. 5791 - 5796
• Main Authors: Lee, Koon-Guan, Xu, Shengli, Kang, Zi-Han, Huo, Jianxin, Huang, Mei, Liu, Dingxiang, Takeuchi, Osamu, Akira, Shizuo, Lam, Kong-Peng
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 10.04.2012; National Acad Sciences
• Subjects: Adaptor Proteins, Vesicular Transport - metabolism; Animals; Antibodies; Antiviral Agents - immunology; Antivirals; Binding sites; Biological Sciences; Cytokines; Cytokines - biosynthesis; Dengue virus; Dengue Virus - immunology; Dengue Virus - physiology; Double stranded RNA; Enzyme Activation; GTPase-Activating Proteins - metabolism; HEK293 Cells; Humans; Interferon-beta - biosynthesis; Macrophage Activation; Macrophages; Macrophages - enzymology; Macrophages - virology; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mutation; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; Protein-Serine-Threonine Kinases - metabolism; Protein-Tyrosine Kinases - deficiency; Protein-Tyrosine Kinases - metabolism; Proto-Oncogene Proteins c-akt - metabolism; Receptors; Rodents; Signal transduction; T cell receptors; Toll like receptors; Toll-Like Receptor 3 - metabolism; Transcription factors; Transcription Factors - metabolism; Virus Replication
• DOI: 10.1073/pnas.1119238109
• ISSN: 0027-8424

Toll-like receptor 3 (TLR3) mediates antiviral response by recognizing double-stranded RNA. Its cytoplasmic domain is tyrosine phosphorylated upon ligand binding and initiates downstream signaling via the adapter TIR-containing adaptor inducing interferon-β (TRIF). However, the kinase responsible for TLR3 phosphorylation remains unknown. We show here that Bruton's tyrosine kinase (BTK)-deficient macrophages failed to secrete inflammatory cytokines and IFN-β upon TLR3 stimulation and were impaired in clearing intracellular dengue virus infection. Mutant mice were also less susceptible to d-galactosamine/p(I:C)-induced sepsis. In the absence of BTK, TLR3-induced phosphoinositide 3-kinase (PI3K), AKT and MAPK signaling and activation of NFκB, IRF3, and AP-1 transcription factors were all defective. We demonstrate that BTK directly phosphorlates TLR3 and in particular the critical Tyr759 residue. BTK point mutations that abrogate or led to constitutive kinase activity have opposite effects on TLR3 phosphorlation. Loss of BTK also compromises the formation of the downstream TRIF/receptor-interacting protein 1 (RIP1)/TBK1 complex. Thus, BTK plays a critical role in initiating TLR3 signaling.