Identification of an Optimal TLR8 Ligand by Alternating the Position of 2'-O-Ribose Methylation

Int J Mol Sci. 2022 Sep 22;23(19):11139. doi: 10.3390/ijms231911139.


Recognition of RNA by receptors of the innate immune system is regulated by various posttranslational modifications. Different single 2'-O-ribose (2'-O-) methylations have been shown to convert TLR7/TLR8 ligands into specific TLR8 ligands, so we investigated whether the position of 2'-O-methylation is crucial for its function. To this end, we designed different 2'-O-methylated RNA oligoribonucleotides (ORN), investigating their immune activity in various cell systems and analyzing degradation under RNase T2 treatment. We found that the 18S rRNA-derived TLR7/8 ligand, RNA63, was differentially digested as a result of 2'-O-methylation, leading to variations in TLR8 and TLR7 inhibition. The suitability of certain 2'-O-methylated RNA63 derivatives as TLR8 agonists was further demonstrated by the fact that other RNA sequences were only weak TLR8 agonists. We were thus able to identify specific 2'-O-methylated RNA derivatives as optimal TLR8 ligands.

Keywords: 2′-O-ribose-methylation; RNase T2; TLR7; TLR8; immune activation.

MeSH terms

  • Ligands
  • Methylation
  • Oligoribonucleotides / metabolism
  • Protein Processing, Post-Translational
  • RNA / metabolism
  • RNA, Ribosomal, 18S / metabolism
  • Ribose
  • Toll-Like Receptor 7* / metabolism
  • Toll-Like Receptor 8* / metabolism


  • Ligands
  • Oligoribonucleotides
  • RNA, Ribosomal, 18S
  • Toll-Like Receptor 7
  • Toll-Like Receptor 8
  • RNA
  • Ribose