May 24, 2001

2 min read

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Scientists Develop New Technique for Silencing Human Genes

By Kate Wong

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Researchers have known for some time that one way to determine what any given gene does is to turn it off and see what happens. Silencing the gene by blocking its so-called messenger RNA¿a technique dubbed RNA interference (RNAi)¿has proved particularly effective in such creatures as nematode worms and fruit flies. In mammalian cells, though, this method seemed to elicit a nonspecific, and therefore uninformative, response¿until now. Findings published today in the journal Nature reveal that RNAi can, in fact, work in mammalian cells. The new results should help scientists study many genes of unknown function that human genome research continues to bring to light.

Researchers induce RNAi in nonmammalian cells by first synthesizing a double-stranded RNA (dsRNA) matching a particular gene sequence and introducing it into a cell, which results in the dsRNA breaking into short pieces. These short interfering RNAs (siRNAs) then trigger the degradation of the matching messenger RNA sequence, thus silencing the gene it belongs to. The new research, conducted by Thomas Tuschl of the University of Gottingen in Germany and his colleagues, reveals that although introducing dsRNA into mammalian cells leads to a nonspecific response, introducing the siRNAs themselves into the cells can initiate RNAi.

RNAi appears to work more effectively than the popular "antisense" techniques for preventing gene expression, although various technical issues must be resolved before it is widely applied to mammalian cells. For one thing, whereas dsRNA can be fed to nematodes for the desired result, delivering siRNAs to mammalian cells is not so simple. All in all, however, the results mark a big step forward. The use of these siRNAs, the researchers write, "holds great promise for analysis of gene function in human cell culture and the development of gene-specific therapeutics."

Kate Wong is an award-winning science writer and senior editor for features at Scientific American, where she has focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for nearly 30 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home to the shores of Kenya’s Lake Turkana in search of the oldest stone tools in the world, as well as to Madagascar on an expedition to unearth ancient mammals and dinosaurs, the icy waters of Antarctica, where humpback whales feast on krill, and a “Big Day” race around the state of Connecticut to find as many bird species as possible in 24 hours. Wong is co-author, with Donald Johanson, of Lucy’s Legacy: The Quest for Human Origins. She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow her on Bluesky @katewong.bsky.social

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