14-3-3ε and 14-3-3σ inhibit Toll-like receptor (TLR)-mediated proinflammatory cytokine induction

J Biol Chem. 2012 Nov 9;287(46):38665-79. doi: 10.1074/jbc.M112.367490. Epub 2012 Sep 14.

Abstract

Toll-like receptors (TLRs) are a group of pattern recognition receptors that play a crucial role in the induction of the innate immune response against bacterial and viral infections. TLR3 has emerged as a key sensor of viral double-stranded RNA. Thus, a clearer understanding of the biological processes that modulate TLR3 signaling is essential. Limited studies have applied proteomics toward understanding the dynamics of TLR signaling. Herein, a proteomics approach identified 14-3-3ε and 14-3-3σ proteins as new members of the TLR signaling complex. Toward the functional characterization of 14-3-3ε and 14-3-3σ in TLR signaling, we have shown that both of these proteins impair TLR2, TLR3, TLR4, TLR7/8, and TLR9 ligand-induced IL-6, TNFα, and IFN-β production. We also show that 14-3-3ε and 14-3-3σ impair TLR2-, TLR3-, TLR4-, TLR7/8-, and TLR9-mediated NF-κB and IFN-β reporter gene activity. Interestingly, although the 14-3-3 proteins inhibit poly(I:C)-mediated RANTES production, 14-3-3 proteins augment Pam(3)CSK(4), LPS, R848, and CpG-mediated production of RANTES (regulated on activation normal T cell expressed and secreted) in a Mal (MyD88 adaptor-like)/MyD88-dependent manner. 14-3-3ε and 14-3-3σ also bind to the TLR adaptors and to both TRAF3 and TRAF6. Our study conclusively shows that 14-3-3ε and 14-3-3σ play a major regulatory role in balancing the host inflammatory response to viral and bacterial infections through modulation of the TLR signaling pathway. Thus, manipulation of 14-3-3 proteins may represent novel therapeutic targets for inflammatory conditions and infections.

Publication types

  • Research Support, Non-U.S. Gov't
  • Retracted Publication

MeSH terms

  • 14-3-3 Proteins / metabolism*
  • CpG Islands
  • Cytokines / metabolism*
  • Electrophoresis, Gel, Two-Dimensional / methods
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Inflammation
  • Mass Spectrometry / methods
  • Models, Biological
  • Myeloid Differentiation Factor 88 / metabolism
  • Poly I-C / metabolism
  • Proteomics / methods
  • Signal Transduction
  • Toll-Like Receptors / metabolism*

Substances

  • 14-3-3 Proteins
  • Cytokines
  • MYD88 protein, human
  • Myeloid Differentiation Factor 88
  • Toll-Like Receptors
  • Poly I-C