Published in: Nature vol. 404, pp.293-296 (March 16, 2000):


"An RNA-Directed Nuclease Mediates Post-Transcriptional Gene Silencing in Drosophila Cells."

Scott M. Hammond, Emily Bernstein, David Beach, and Gregory J. Hannon. 



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 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, ~25-nucleotide RNA species which may confer specificity to the enzyme through homology to the substrate mRNAs. 


Additional References:

1.  "Selective Gene De-Repression by De-Repressor RNA".

2. "Selective Control of  DNA Helix Openings during Gene Regulation".

3. "Nuclear RNA Species Activate DNA Transcription within Chromatin".

4. "Oncogenes as Molecular Targets within Active Chromatin".

5. "A Genetic Link between Co-Suppression and RNA Interference in C. elegans".


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euchromatin: "the most active portion of the genome within the cell nucleus".