An essential role for RIG-I in toll-like receptor-stimulated phagocytosis

Cell Host Microbe. 2009 Aug 20;6(2):150-61. doi: 10.1016/j.chom.2009.06.008.


Retinoic acid-inducible gene-I (RIG-I) plays an important role in antiviral response by recognizing double-stranded RNA. Here we demonstrate an unanticipated role of RIG-I in Toll-like receptor (TLR)-stimulated phagocytosis. Stimulation with lipopolysaccharide (LPS), a ligand of TLR4, induced the expression of RIG-I in macrophages. Depletion of RIG-I by RNAi or gene targeting inhibited the LPS-induced phagocytosis of bacteria. Cellular processes involved in phagocytosis, such as small GTPase Cdc42/Rac1 activation, actin polymerization, and actin-regulator Arp2/3 recruitment, were also impaired in RIG-I-deficient macrophages activated by LPS. Moreover, RIG-I(-/-) mice were found to be more susceptible to infection with Escherichia coli as compared to wild-type mice. Thus, the regulatory functions of RIG-I are strikingly broad, including a role not only in antiviral responses but in antibacterial responses as well.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin-Related Protein 2-3 Complex / metabolism
  • Animals
  • Cell Line
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / immunology*
  • Escherichia coli / immunology*
  • Escherichia coli Infections / immunology
  • GTPase-Activating Proteins / metabolism
  • Gene Silencing
  • Macrophages / microbiology*
  • Mice
  • Mice, Knockout
  • Neuropeptides / metabolism
  • Phagocytosis / immunology*
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Survival Analysis
  • Toll-Like Receptor 4 / immunology*
  • rac GTP-Binding Proteins / metabolism
  • rac1 GTP-Binding Protein


  • Actin-Related Protein 2-3 Complex
  • Arhgap31 protein, mouse
  • GTPase-Activating Proteins
  • Neuropeptides
  • RNA, Small Interfering
  • Rac1 protein, mouse
  • Toll-Like Receptor 4
  • Ddx58 protein, mouse
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases
  • rac GTP-Binding Proteins
  • rac1 GTP-Binding Protein