Research in Progress

Gene Therapy

“Fast and Cheap”: siRNA in Gene Silencing

Researchers at the Stanford University School of Medicine recently simplified a technique that results in gene silencing (or disabling). This technique was formerly limited by difficulty and expense. In order to see how a gene works, researchers often silence (use molecular techniques to “turn off”) that gene and observe the physiological effects of its absence. Short interference RNA (siRNA) is commonly used in the RNA interference (RNAi) technique to stop the translation of the particular gene of interest into protein. A benefit of siRNA is that, since it only targets the specific gene in question, it leaves behind a large number of genes for further study. (For more information on how siRNA works, please see New Scientist reports on gene therapy research.)

Three pathology graduate students developed a systematic method of using siRNAs to disable all genes in a given cell. By making their own siRNAs and cataloguing them in an siRNA library, the students were able to avoid the high costs of tailoring individual siRNAs to each gene in the cell. Researchers will be able to take siRNAs from the library “like books from a shelf” to test them on genes.

How did the students manage to circumvent the process of making one siRNA for each of the tens of thousands of genes in one cell? They used an enzyme to cut siRNA into short snippets and inserted these snippets into pieces of circular DNA (also known as plasmids). When placed into a cell, the plasmids began making siRNA. The students tested their plasmid technique on three known genes and were able to successfully disable them.

This greatly simplified, costeffective way to silence genes may lead to the discovery of genes that are involved in various diseases (including neurodegenerative disorders) and develop drugs that target them, especially the expression of their abnormal forms (such as the form of the Huntington gene -which is called the HD allele- that produces the mutant huntingtin protein.)

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Last Modified: 04/12/2007

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