The latest twist on the Nobel prizewinning method of RNA interference, or RNAi, could prove to be a real turn-on. Whereas standard RNAi silences a target gene, switching protein production off, the new technique boosts gene activity, providing a genetic 鈥渙n鈥� switch.
RNAi can silence genes in two ways. It can block the messenger RNA that is the intermediate between gene and protein and it can also interfere with 鈥減romoter鈥� sequences that boost a gene鈥檚 activity. It was while investigating this second phenomenon that Long-Cheng Li of the University of California, San Francisco, and his colleagues stumbled on the new method, dubbed RNA activation.
Li tried to silence several genes in human cells using short pieces of double-stranded RNA, 21 bases long. But to his surprise, he found that they had precisely the opposite effect (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0607015103).
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Although the exact mechanism remains unclear, Li鈥檚 team has already found that it requires a protein called Ago2, which is also involved in the standard RNAi process. Li believes RNA activation could find widespread use, for example in treating cancer by boosting the activity of tumour suppressor genes.
