Judy Lieberman is leading an effort to silence messages sent from disease-related genes to our tissues and organs. The silencing technique is being tested in humans and animals suffering from a variety of disorders, including hepatitis, AIDS, diabetes, and macular degeneration, a major cause of blindness in older people. Staff photo Stephanie Mitchell/Harvard News Office |
Viruses get the silent treatment, any disease is a targetFebruary 15, 2007By William J. Cromie
What do you do if you're sure you've found a way to knock out the AIDS virus but you can't get the medicine into infected cells? That was the problem faced by Judy Lieberman, a professor of pediatrics at Harvard Medical School. Using tiny bits of genetic material, she and her research team have blocked messages sent from genes that underlie diseases like genital herpes and hepatitis. "We used the technique to protect mice against liver failure," she says. "Eighty percent of the protected animals lived; 80 percent of those without the protection died." Such protection is provided by small molecules of RNA (ribonucleic acid), which interfere with messages sent from genes instructing various proteins to be made. Interference RNA (RNAi) "tears up" these messages. For example, if a gene in the liver sends a signal that would lead to destruction of a liver cell, RNAi can block the signal. The RNAi itself is not destroyed in the process and survives to silence additional unwanted messages. Because all genes work through signals they send to other parts of a cell, RNAi might be used to silence an incredible variety of diseases, including AIDS, type 1 diabetes, rheumatoid arthritis, blinding macular degeneration, cancers, and, possibly, Asian bird flu. Studies already are under way to use RNAi to block human genes involved in AIDS, hepatitis, muscle-wasting Lou Gerhrig's disease, macular degeneration, and breast cancer. In principle, Lieberman says, "virtually any disease could be targeted by new classes of drugs based on RNAi." During the 2007 annual meeting of the American Association for the Advancement of Science in San Francisco (Feb. 15-19), Lieberman will describe how she beat long odds to develop a new process that can get RNAi molecules into specific cells. For example, it might be used to direct RNAi drugs into cells infected by HIV, the virus that causes AIDS. The process, licensed to a company in Cambridge, Mass., called Alnylam Pharmaceuticals, should help all researchers now working on these types of drugs. |
