The nitrone spin trap 5,5‑dimethyl‑1‑pyrroline N‑oxide binds to toll-like receptor-2-TIR-BB-loop domain and dampens downstream inflammatory signaling

Biochim Biophys Acta Mol Basis Dis. 2019 Jun 1;1865(6):1152-1159. doi: 10.1016/j.bbadis.2019.01.005. Epub 2019 Jan 23.

Abstract

The nitrone spin trap 5,5‑dimethyl‑1‑pyrroline N‑oxide (DMPO) dampens endotoxin-induced and TLR4-driven priming of macrophages, but the mechanism remains unknown. The available information suggests a direct binding of DMPO to the TIR domain, which is shared between TLRs. However, TLR2-TIR domain is the only TLR that have been crystallized. Our in silico data show that DMPO binds to four specific residues in the BB-loop within the TLR2-TIR domain. Our functional analysis using hTLR2.6-expressing HEKs cells showed that DMPO can block zymosan-triggered-TLR2-mediated NF-κB activation. However, DMPO did not affect the overall TLR2-MyD88 protein-protein interaction. DMPO binds to the BB-loop in the TIR-domain and dampens downstream signaling without affecting the overall TIR-MyD88 interaction. These data encourage the use of DMPO-derivatives as potential mechanism-based inhibitors of TLR-triggered inflammation.

Keywords: BB-loop; DMPO; Mechanism-based drug; Signal transduction; TIR domain; TLR2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclic N-Oxides / chemistry
  • Cyclic N-Oxides / metabolism*
  • HEK293 Cells
  • Humans
  • Inflammation / immunology
  • Inflammation / metabolism*
  • Mice
  • Molecular Dynamics Simulation
  • Myeloid Differentiation Factor 88 / chemistry
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B / chemistry
  • NF-kappa B / metabolism
  • Nitrogen Oxides / chemistry
  • Nitrogen Oxides / metabolism*
  • Protein Binding
  • Protein Domains
  • RAW 264.7 Cells
  • Signal Transduction*
  • Spin Labels*
  • Toll-Like Receptor 2 / antagonists & inhibitors
  • Toll-Like Receptor 2 / chemistry
  • Toll-Like Receptor 2 / metabolism*

Substances

  • Cyclic N-Oxides
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • Nitrogen Oxides
  • Spin Labels
  • Toll-Like Receptor 2
  • nitrones
  • 5,5-dimethyl-1-pyrroline-1-oxide