Scaffolding adaptor protein Gab1 is required for TLR3/4- and RIG-I-mediated production of proinflammatory cytokines and type I IFN in macrophages

J Immunol. 2010 Jun 1;184(11):6447-56. doi: 10.4049/jimmunol.0901750. Epub 2010 Apr 30.

Abstract

RIG-I-like helicases and TLRs are critical sensors in the induction of type I IFN and proinflammatory cytokines to initiate innate immunity against invading pathogens. However, the mechanisms for the full activation of TLR and RIG-I-triggered innate response remain to be fully investigated. Grb2-associated binder 1 (Gab1), a member of scaffolding/adaptor proteins, can mediate signal transduction from many receptors, however, whether and how Gab1 is required for TLR and RIG-I-triggered innate responses remain unknown. In this study, we demonstrated that Gab1 significantly enhances TLR4-, TLR3-, and RIG-I-triggered IL-6, IL-1beta, and IFN-alpha/beta production in macrophages. Gab1 knockdown in primary macrophages or Gab1 deficiency in mouse embryonic fibroblasts significantly suppresses TLR3/4- and RIG-I-triggered production of IL-6, IL-1beta, and IFN-alpha/beta. Consistently, Gab1 deficiency impairs vesicular stomatitis virus (VSV) infection-induced IFN-alpha/beta production. In addition to promoting both MyD88- and TLR/IL-1 receptor domain-containing adaptor protein inducing IFN-beta-dependent MAPKs and NF-kappaB activation, Gab1 enhances PI3K/Akt activation by directly binding p85 in TLR signaling and VSV infection. Accordingly, Gab1 inhibits VSV replication and VSV infection-induced cell damage by inducing type I IFNs and IFN-inducible gene expression via PI3K/Akt pathway. Therefore, Gab1 is needed for full activation of TLR3/4- and RIG-I-triggered innate responses by promoting activation of PI3K/Akt, MAPKs, and NF-kappaB pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Blotting, Western
  • Cell Separation
  • Cytokines
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Flow Cytometry
  • Gene Expression
  • Gene Expression Profiling
  • Gene Expression Regulation / immunology
  • Immunoprecipitation
  • Interferon Type I / immunology
  • Interferon Type I / metabolism*
  • Macrophages / immunology
  • Macrophages / metabolism*
  • Membrane Proteins / immunology
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mitogen-Activated Protein Kinases / immunology
  • Mitogen-Activated Protein Kinases / metabolism
  • NF-kappa B / immunology
  • NF-kappa B / metabolism
  • Nerve Tissue Proteins / immunology
  • Nerve Tissue Proteins / metabolism*
  • Phosphatidylinositol 3-Kinases / immunology
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoproteins / immunology
  • Phosphoproteins / metabolism*
  • RNA Interference
  • Receptors, Cell Surface
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / immunology
  • Toll-Like Receptor 3 / immunology
  • Toll-Like Receptor 3 / metabolism*
  • Toll-Like Receptor 4 / immunology
  • Toll-Like Receptor 4 / metabolism*
  • Transfection

Substances

  • Adaptor Proteins, Signal Transducing
  • Cytokines
  • Gab1 protein, mouse
  • Interferon Type I
  • Membrane Proteins
  • NF-kappa B
  • Nerve Tissue Proteins
  • Phosphoproteins
  • Receptors, Cell Surface
  • Robo3 protein, mouse
  • TLR3 protein, mouse
  • Tlr4 protein, mouse
  • Toll-Like Receptor 3
  • Toll-Like Receptor 4
  • Mitogen-Activated Protein Kinases