RNA interference (RNAi) is a post-transcriptional process triggered by the introduction of double-stranded RNA (dsRNA) which leads to gene silencing in a sequence-specific manner. The first evidence that dsRNA could achieve efficient gene silencing through RNAi came from studies on the nematode Caenorhabditis elegans. Further analyses in the fruit fly Drosophila melanogaster have contributed greatly toward understanding the biochemical nature of the RNAi pathway [1].
Long dsRNAs are cleaved by the RNase III family member, Dicer, into 19-23 nucleotides (nt) fragments with 5’ phosphorylated ends and 2-nt unpaired and unphosphorylated 3’ ends.