RNA interference and interferon.

Extract: Over the past 5 years, the phenomenon of RNA interference (RNAi) has progressed from being considered a mysterious response to double-stranded RNA (dsRNA) in the nematode C. elegans to the latest potential therapeutic tool to silence gene expression in certain diseases such as cancer or viral infections. However, the application of this biological phenomenon as a powerful research tool is not as clear-cut as scientists had initially hoped. dsRNA, the initiator of RNAi, is not made as a result of normal cellular processes, but is considered a warning to the cell of potential danger. Foreign dsRNA molecules can be formed through the transcription of potentially harmful transposons that contain inverted repeat sequences, as well as through the replication process of the majority of viruses during an infection. In organisms, such as the aforementioned nematode C. elegans and Drosophila, that respond to dsRNA-containing challenges through RNAi, the foreign dsRNA is recognized and cleaved into 21-23 nucleotide short interfering (si) RNAs. The siRNA is then incorporated into the RNA Induced Silencing Complex, which targets the mRNA of homologous sequence for degradation.