An RNA-directed nuclease mediates post-transcriptional gene silencing in Drosophila cells.
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 manner. These responses, called RNA interference or post-transcriptional gene silencing, may provide anti-viral defence, modulate transposition or regulate gene expression. 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, approximately 25-nucleotide RNA species which may confer specificity to the enzyme through homology to the substrate mRNAs.
Hammond
S M
SM
Genetica, Inc., Cold Spring Harbor, New York 11724, USA.
Bernstein
E
E
Beach
D
D
Hannon
G J
GJ
D000818:Animals; D016827:CD8 Antigens / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D002478:Cells, Cultured; D019927:Cyclin E / Q000235:genetics; D004330:Drosophila; D004722:Endoribonucleases / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D007763:Lac Operon; D012330:RNA, Double-Stranded / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D013379:Substrate Specificity; D014158:Transcription, Genetic; D014162:Transfection
D016827:CD8 Antigens; D019927:Cyclin E; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D004722:Endoribonucleases; C044803:ds RNase