RNA interference

RNA interference (RNAi) is a relatively newly-discovered mechanism in which the presence of small fragments of dsRNA whose sequence matches a given gene leads to the suppression of the expression of that gene.

RNAi appears to be a highly potent and specific process which is actively carried out by special mechanisms in the cell. The precise details of how it works are still unclear, but it involves breaking down mRNA transcripts before they undergo translation. It is thought to have evolved as a defence against the expression of retrovirus genes integrated into the host genome as provirus. It was first discovered in plants, but has now been found in many other eukaryotes.

RNAi has recently been applied as an experimental technique to "knockout" genes in model organisms for experimental analysis. (Because RNAi may not totally abolish expression of a gene, using it against a gene is sometimes referred as a "knockdown", to distinguish it from procedures in which the DNA sequence encoding a gene is removed.) Most functional genomics applications of RNAi were made on Caenorhabditis elegans, a worm that's a model organism in genetics research.

The dsRNA that trigger RNAi may be usable as drugs. For example, dsRNA could repress essential genes in eukaryotic human pathogens or viruses that are dissimilar from any human genes, which would be analogous to how existing drugs work. Such applications of RNAi are currently only speculative.

Compare antisense mRNA[?].

External links

http://www.ambion.com/techlib/tn/73/735

http://www.macalester.edu/~montgomery/RNAi