There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Double-stranded RNA (dsRNA) induces sequence-specific posttranscriptional gene silencing
in many organisms by a process known as RNA interference (RNAi). Using a Drosophila
in vitro system, we demonstrate that 21- and 22-nt RNA fragments are the sequence-specific
mediators of RNAi. The short interfering RNAs (siRNAs) are generated by an RNase III-like
processing reaction from long dsRNA. Chemically synthesized siRNA duplexes with overhanging
3' ends mediate efficient target RNA cleavage in the lysate, and the cleavage site
is located near the center of the region spanned by the guiding siRNA. Furthermore,
we provide evidence that the direction of dsRNA processing determines whether sense
or antisense target RNA can be cleaved by the siRNA-protein complex.