Ribonuclease H2 (
RNase H2) is a nuclease that specifically hydrolyzes
RNA residues in
RNA-
DNA hybrids. Mutations in the
RNase H2
enzyme complex have been identified in the
genetic disorder Aicardi-Goutières syndrome (AGS), which has similarities to the
autoimmune disease systemic lupus eryrthrematosis (SLE). The
RNase H2
enzyme has also been recently implicated as a key genome surveillance
enzyme. Therefore, small-molecule modulators of
RNase H2 activity may have utility in
therapeutics and as tools to investigate the cellular functions of
RNase H2. A fluorescent quench assay, measuring cleavage of an
RNA-
DNA duplex substrate by recombinant
RNase H2, was developed into a high-throughput format and used to screen a 48 560 compound library. A hit validation strategy was subsequently employed, leading to the identification of two novel inhibitor compounds with in vitro nanomolar range inhibition of
RNase H2 activity and >100-fold selectivity compared with
RNase H type 1. These compounds are the first small-molecule inhibitors of
RNase H2 to be reported. They and their derivatives should provide the basis for the development of tool compounds investigating the cellular functions of the
RNase H2
enzyme, and, potentially, for pharmacological manipulation of
nucleic acid-mediated immune responses.