RNA interference: travelling in the cell and gaining functions? Trends Genet

Double-stranded RNA can induce the degradation of homologous RNAs in organisms as diverse as pro-tozoa, animals, plants and fungi, resulting in post-transcriptional gene silencing. But in some species, RNA-mediated processes can also lead to translational repression, DNA methylation, heterochromatin for-mation or DNA elimination. In some situations, amplifi-cation of the ‘trigger ’ double-stranded RNA seems to be required for efficient silencing. These findings imply that RNA-mediated mechanisms can control gene expression at both the transcriptional and the post-transcriptional level, and that they can operate in the nuclear and the cytoplasmic compartments. Double-stranded RNA (dsRNA) can induce many different epigenetic gene-silencing processes in eukaryotes, includ