An RNA-directed nuclease mediates post-transcriptional gene silencing in Drosophila cells

Top Cited Papers
Publisher Website
Google Scholar
Abstract
In a diverse group of organisms that includes Caenorhabditis elegans , Drosophila, planaria, hydra, trypanosomes, fungi and plants, the introduction of double-stranded RNAs inhibits gene expression in a sequence-specific manner1,2,3,4,5,6,7. These responses, called RNA interference or post-transcriptional gene silencing, may provide anti-viral defence, modulate transposition or regulate gene expression1,6,8,9,10. We have taken a biochemical approach towards elucidating the mechanisms underlying this genetic phenomenon. Here we show that ‘loss-of-function’ phenotypes can be created in cultured Drosophila cells by transfection with specific double-stranded RNAs. This coincides with a marked reduction in the level of cognate cellular messenger RNAs. Extracts of transfected cells contain a nuclease activity that specifically degrades exogenous transcripts homologous to transfected double-stranded RNA. This enzyme contains an essential RNA component. After partial purification, the sequence-specific nuclease co-fractionates with a discrete, ∼25-nucleotide RNA species which may confer specificity to the enzyme through homology to the substrate mRNAs.