Toll-like receptor 3 associates with c-Src tyrosine kinase on endosomes to initiate antiviral signaling

EMBO J. 2006 Jul 26;25(14):3335-46. doi: 10.1038/sj.emboj.7601222. Epub 2006 Jul 6.


Double-stranded RNA (dsRNA) is produced during the replication cycle of most viruses and triggers antiviral immune responses through Toll-like receptor 3 (TLR3). However, the molecular mechanisms and subcellular compartments associated with dsRNA-TLR3-mediated signaling are largely unknown. Here we show that c-Src tyrosine kinase is activated by dsRNA in human monocyte-derived dendritic cells, and is recruited to TLR3 in a dsRNA-dependent manner. DsRNA-induced activation of interferon-regulatory factor 3 and signal transducer and activator of transcription 1 was abolished in Src kinase-deficient cells, and restored by adding back c-Src, suggesting a central role of c-Src in antiviral immunity. We also provide evidence that TLR3 is localized in the endoplasmic reticulum of unstimulated cells, moves to dsRNA-containing endosomes in response to dsRNA, and colocalizes with c-Src on endosomes containing dsRNA in the lumen. These results provide novel insight into the molecular mechanisms of TLR3-mediated signaling, which may contribute to the understanding of innate immune responses during viral infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CSK Tyrosine-Protein Kinase
  • Cells, Cultured
  • Dendritic Cells
  • Endosomes / enzymology*
  • Endosomes / physiology
  • Endosomes / virology*
  • Enzyme Activation / physiology
  • HeLa Cells
  • Humans
  • Interferon Regulatory Factor-3 / metabolism
  • Mice
  • Mice, Knockout
  • Protein-Tyrosine Kinases / metabolism
  • Protein-Tyrosine Kinases / physiology*
  • RNA, Double-Stranded / antagonists & inhibitors*
  • RNA, Double-Stranded / physiology
  • Rhinovirus / genetics
  • Rhinovirus / physiology*
  • STAT1 Transcription Factor / metabolism
  • Signal Transduction / physiology*
  • Toll-Like Receptor 3 / metabolism
  • Toll-Like Receptor 3 / physiology*
  • src-Family Kinases


  • Interferon Regulatory Factor-3
  • RNA, Double-Stranded
  • STAT1 Transcription Factor
  • STAT1 protein, human
  • TLR3 protein, human
  • Toll-Like Receptor 3
  • Protein-Tyrosine Kinases
  • CSK Tyrosine-Protein Kinase
  • src-Family Kinases
  • CSK protein, human