Common age: worms, yeast, and people share genes for aging

Science News, March 15, 2008 by Ewen Callaway

Genetic changes that slow aging in roundworms also keep the lowly baker's yeast from going rapidly over the hill, new research shows. Humans have many of these same genes, and drugs targeting them might eventually turn back our own biological clocks.

Aging shouldn't be an evolved trait, with common genes shared by distant species, many scientists once reasoned. Most animals pass on their DNA long before aging takes its toll. And throughout much of life's history, animals were likelier to die from starving or being eaten than from growing old, says biologist Brian Kennedy, who led the study.

But recent research on aging in yeast, flies, and worms has turned up a smattering of genes that lengthen life span when removed. More than 1 billion years of evolution separates yeast and roundworms.

Kennedy and his colleague Matt Kaeberlein, both of the University of Washington in Seattle, scoured journal articles for genes tied to long life in the roundworm Caenorhabditis elegans--a popular animal used to study aging. The researchers identified 276 worm genes that enhance longevity when deactivated, then tested to see if deleting them might slow aging in yeast as well.

Kennedy and Kaeberlein's team found 25 aging-related genes shared by yeast and worms; 22 of these genes had not previously been linked to life span in yeast. Humans have 15 of the genes, the team reports in the April Genome Research.

A surprisingly high number of the genes are involved in cells' response to nutrients, Kennedy says. Cutting calories can boost life span in nearly every organism, from yeast to Labrador retrievers. "The things that govern aging are really closely linked to the amount of nutrients in the environment," he says. In times of feast, organisms grow fast, live hard, and die early. With less grub around, an animal might focus on protecting its cells from the damage that spurs aging, he says.

Nutrition explains why yeast, worms, and people have the same aging genes, agrees Pankaj Kapahi of the Buck Institute in Novato, Calif. Studying less complex organisms offers a quick way to home in on genes involved in aging--and possible treatments. "A lot of people don't think yeast aging has anything to do with human aging," he says. "This really dispels that belief."