Selective inhibition of ADAR2-catalyzed editing of the serotonin 2c receptor pre-mRNA by a helix-threading peptide.

RNA editing by adenosine deamination is a form of epigenetic control of gene expression wherein the ADAR enzymes convert adenosine to inosine in RNA often changing the meaning of codons. The pre-mRNA for the 2c subtype of serotonin receptor (5-HT2cR) is shown here to support small molecule binding near known editing sites. Furthermore, a helix-threading peptide binds this site and inhibits the in vitro reaction of ADAR2 in an RNA-substrate selective manner. This is the first example of substrate-selective inhibition of editing by an RNA-binding small molecule and sets the stage for the development of new reagents capable of controlling gene function through manipulation of mRNA editing.