The inducible nitric-oxide synthase (iNOS)/Src axis mediates toll-like receptor 3 tyrosine 759 phosphorylation and enhances its signal transduction, leading to interferon- β synthesis in macrophages

Ming Yu Hsieh, Miao Ying Chang, Yen Jen Chen, Yung Kuo Li, Tsung Hsien Chuang, Guann Yi Yu, Chun Hei Antonio Cheung, Hui Chen Chen, Ming Chei Maa, Tzeng Horng Leu

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15 Citations (Scopus)

Abstract

Double-stranded RNA (dsRNA) induces phosphorylation of Toll-like receptor 3 (TLR3) at tyrosine 759 and subsequently triggers signaling pathways to promote interferon-β (IFN-β) production. In this study, we found that dsRNA stimulation induces biphasic TLR3 Tyr-759 phosphorylation in macrophages. In addition to the immediate TLR3 Tyr-759 phosphorylation, we identified a second wave of Tyr-759 phosphorylation accompanied by an increase of both Src and ifn-β transcription in the later phase of dsRNA stimulation. Interestingly, Src phosphorylated TLR3 Tyr-759 in vitro and in vivo. However, knockdown of Src abolished the late phase of TLR3 Tyr-759 phosphorylation and decreased the nuclear accumulation of interferon regulatory factors 3 and 7 (IRF3 and -7) and IFN-β production. Reintroduction of Src restored all of these molecular changes. Notably, via down-regulation of Src, dsRNA-elicited TLR3 Tyr-759 phosphorylation, the nuclear accumulation of IRF3/IRF7, and IFN-β generation were inhibited in inducible nitric-oxide synthase (iNOS)-null macrophages. TLR3 knockdown destabilized Src and reduced the nuclear level of IRF3/IRF7 and IFN-β production in macrophages exposed to LPS (a TLR4 ligand known to induce Src and IFN-β expression). Ectopic expression of wild type TLR3, but not its 759-phenylalanine mutant, restored Src activity and ifn-β transcription. Taken together, these results suggested an essential role of the iNOS/Src/TLR3 axis in IFN-β production in macrophages.

Original languageEnglish
Pages (from-to)9208-9220
Number of pages13
JournalJournal of Biological Chemistry
Volume289
Issue number13
DOIs
Publication statusPublished - 2014 Mar 30

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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