Dampening the silencing effect of RNA interference in mammals.

RNAi (RNA interference) refers to the suppression of expression of a target gene (mainly at the post-transcriptional or translational level) induced by small (21-23 nucleotides) RNA molecules, including siRNA (small interfering RNA). Suppression of gene expression by RNAi represents an important part of the regulation of gene expression. Interestingly, recent advancements in RNAi research support the notion that RNAi can be regulated just as an ordinary gene. In this issue of the Biochemical Journal, Hong et al. report their finding that suppression of RNAi is triggered by a high dose of siRNA in mice, and the suppression of RNAi in mice is related to eri-1 (enhanced RNA interference). Eri-1 is an RNaseT enzyme initially found in Caenorhabditis elegans that can degrade double-stranded RNA with 3' overhangs. The results presented by Hong et al. have the potential to be extended and contribute to our knowledge about the regulation of RNAi in mammals.