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Nobel Prize in Medicine Goes to Two U.S. Scientists

Aalok Mehta
National Geographic News
October 2, 2006
 
Biologists Andrew Z. Fire and Craig C. Mello will split the 2006 Nobel Prize in Physiology or Medicine for their work uncovering how certain genes in the body are inactivated.

The Nobel Assembly at the Karolinska Institute in Stockholm, Sweden, announced today that Fire, of Stanford University School of Medicine in California, and Mello, of the University of Massachusetts Medical School in Worcester, will each receive half of the prize, worth 10 million Swedish kronor (1.4 million U.S. dollars).

The pair is being honored for their discovery of the mechanism behind RNA interference, a process that plants, animals, and humans use to "silence" certain genes.

The finding opened the way for an entirely new type of treatment for many ailments such as AIDS or cancer: knocking out expression of the disease-causing gene.

"This year's Nobel Laureates have discovered a fundamental mechanism for controlling the flow of genetic information," the institute said in a press release.

(Get more information about the winners from the Nobel Foundation.)

Gene Silencing

DNA holds the information needed to build all the proteins that make life possible. The information in a gene is first copied into a molecule known as mRNA (messenger RNA), which is then used as a template for making a protein (get a genetics overview.)

But unlike DNA, which generally exists only as a double-stranded molecule with two matching sides, mRNA is single-stranded.

Fire and Mello found that injecting a cell with the matching strand for a certain mRNA silences all expression of the associated gene—the protein is simply not made. The scientists reported their discoveries in a 1998 issue of the journal Nature.

The matching strand binds to the target RNA to create a double-stranded RNA molecule, similar to DNA.

This double-stranded RNA, scientists later discovered, is destroyed by a set of proteins as a natural defense mechanism against viruses, as well as a tool to regulate the expression of certain genes.

Some of these proteins "remember" the RNA's code and destroy future copies of the associated single-stranded mRNA as well.

"This method has already become an important research tool in biology and biomedicine," according to the Karolinska Institute. "In the future, it is hoped that it will be used in many disciplines, including clinical medicine and agriculture."

Biologists now routinely use the technique to explore gene pathways, and scientists have successfully inactivated genes in humans and lab animals.

This discovery "gives people a method to silence particular genes and look and see what happens, so they can identify what each gene does," said David Bartel, a biology professor at the Massachusetts Institute of Technology in Cambridge.

"Researchers have done this for most genes in the worm, and for most genes in human cells in culture as well."

Group Effort

Researchers also hope that RNA interference can silence damaged or dangerous genes that cause cancer, heart diseases, infections, and other conditions. (Related: "New DNA Mapping Project to Trace Genetic Ills" [October 2005].)

It's "just really, really exciting how many different fields, seemingly unrelated, have just merged together with the understanding of the mechanism," Mello said in an interview with the Nobel Foundation.

"As the understanding grows, we just seem to be bringing together these very distant-looking, sort-of-unrelated looking stories ... [they] just keep coming together and unfolding in beautiful ways."

"I am very honored that our work has received such positive attention," Fire said in a statement released by the Washington, D.C.-based Carnegie Institution, where he performed the RNA interference research.

"Science is a group effort. Please recognize that the recent progress in the field of RNA-based gene silencing has involved original scientific inquiry from research groups around the world," he continued.

"Any prize recognition should go to the many scientists who have made individual contributions, and to the spirit of scientific community that has allowed information and ideas to flow freely."

Update: October 4, 2006

On Tuesday U.S. scientists John C. Mather and George F. Smoot were awarded the 2006 Nobel Prize in Physics for their research helping to solidify the big bang theory of the origin of the universe.

And on Wednesday U.S. biologist Roger D. Kornberg won the 2006 Nobel Prize in Chemistry for helping to unravel how cells make proteins using genetic information.

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