In the early 2000s, RNAi was a hot topic. The science world was abuzz with all the possibilities that harnessing this natural process could hold. And why not? The idea of posttranscriptionally silencing genes using only a small fragment of double-stranded RNA is huge—big enough to earn the scientists who discovered it a Nobel Prize in 2006.
The process of RNAi starts with short (~70 nucleotieds), double-stranded fragments of RNA called short hairpin RNAs (shRNA). These shRNAs are exported into the cytoplasm and cleaved by the enzyme Dicer into smaller pieces of RNA that are about 21 nucleotides long and are referred to as small interfering RNAs (siRNA). The siRNAs reduce or stop expression of proteins through a sequence of events where the antisense strand of the siRNA is incorporated into and RNA-induced silencing complex (RISC), which then attaches to and degrades its complimentary messenger RNA, thereby reducing or completely stopping expression.
It turned out, however, that harnessing the promise of RNAi was a little trickier than anticipated. Continue reading “RNAi: The Dream Makes a Comeback”