Unlike conventional RNA interference techniques, CRISPR interference allows any number of individual genes to be silenced at the same time, Qi said. In addition, it acts more crisply, if you will, by not turning off untargeted genes the way RNA interference techniques do.
Gene switching by RNA interference was identified more than a decade ago, launching a new research field that has spawned a Nobel Prize and billion-dollar biotech firms. In January, the U.S. Food and Drug Administration announced its first approval of an injectable disease therapy based on a similar interference strategy, a drug to treat a rare form of high cholesterol.
RNA interference blocks the messenger RNA that drives protein protection based on the blueprint contained within a gene's DNA sequence. By preventing protein production, RNA interference may be used to get around the problem of difficult-to-target proteins, a frequent challenge in drug development.
But CRISPR interference acts one step earlier in the cell's protein manufacturing process. "The horse has already left the barn with RNA interference, in the sense that the RNA message already has been transcribed from DNA," said Jonathan Weissman, PhD, a Howard Hughes Medical Investigator and professor of cellular and molecular pharmacology, who is another senior author on the work. "With CRISPR interference, we can prevent the message from being written."
CRISPR an acronym for "clustered regularly interspaced short palindromic repeats" is a system that bacteria use to defend themselves against viruses. CRISPR acts like a vaccine, incorporating bits of genes from viruses. Bacteria can reference this library of virus genes to recognize and attack viral invaders.
Qi and colleagues used a protein from this system, called Cas9, as a chassis into which they can ins
|Contact: Jeffrey Norris|
University of California - San Francisco