Self protection from anti-viral responses--Ro52 promotes degradation of the transcription factor IRF7 downstream of the viral Toll-Like receptors

PLoS One. 2010 Jul 26;5(7):e11776. doi: 10.1371/journal.pone.0011776.

Abstract

Ro52 is a member of the TRIM family of single-protein E3 ligases and is also a target for autoantibody production in systemic lupus erythematosus and Sjögren's syndrome. We previously demonstrated a novel function of Ro52 in the ubiquitination and proteasomal degradation of IRF3 following TLR3/4 stimulation. We now present evidence that Ro52 has a similar role in regulating the stability and activity of IRF7. Endogenous immunoprecipitation of Ro52-bound proteins revealed that IRF7 associates with Ro52, an effect which increases following TLR7 and TLR9 stimulation, suggesting that Ro52 interacts with IRF7 post-pathogen recognition. Furthermore, we show that Ro52 ubiquitinates IRF7 in a dose-dependent manner, resulting in a decrease in total IRF7 expression and a subsequent decrease in IFN-alpha production. IRF7 stability was increased in bone marrow-derived macrophages from Ro52-deficient mice stimulated with imiquimod or CpG-B, consistent with a role for Ro52 in the negative regulation of IRF7 signalling. Taken together, these results suggest that Ro52-mediated ubiquitination promotes the degradation of IRF7 following TLR7 and TLR9 stimulation. As Ro52 is known to be IFN-inducible, this system constitutes a negative-feedback loop that acts to protect the host from the prolonged activation of the immune response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Interferon Regulatory Factor-7 / genetics
  • Interferon Regulatory Factor-7 / metabolism*
  • Interferon-alpha / metabolism
  • Mice
  • Mice, Knockout
  • Protein Binding
  • Ribonucleoproteins / genetics
  • Ribonucleoproteins / metabolism*
  • Toll-Like Receptor 7 / genetics
  • Toll-Like Receptor 7 / metabolism
  • Toll-Like Receptor 9 / genetics
  • Toll-Like Receptor 9 / metabolism
  • Toll-Like Receptors / genetics
  • Toll-Like Receptors / metabolism*
  • Ubiquitination

Substances

  • IRF7 protein, human
  • Interferon Regulatory Factor-7
  • Interferon-alpha
  • Ribonucleoproteins
  • SS-A antigen
  • Toll-Like Receptor 7
  • Toll-Like Receptor 9
  • Toll-Like Receptors