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"Anti-Aging Hormone" Found in Mice; May Help Humans

Brian Handwerk
for National Geographic News
August 25, 2005
 
Researchers have dramatically increased the life spans of mice by genetically engineering them to overproduce a protein called klotho. Not surprisingly, the discovery has spurred speculation that klotho could help humans live longer.

"We overexpressed the klotho gene to suppress aging, and we found that the average life span was 20 to 30 percent longer than in control animals," said pathologist Makoto Kuro-O, of the University of Texas' Southwestern Medical Center in Dallas.

The gene regulates production of klotho protein, which the study team says works like an anti-aging hormone. Kotho is involved in the suppression of insulin-signaling pathways—a process that has been shown to increase the life spans of worms and flies.

"We concluded that the klotho gene is an aging-suppression gene that can extend life span when overexpressed and accelerate aging when disrupted," said Kuro-O, who was on the study team. Their findings will be published in tomorrow's issue of the journal Science.

Benefit to Humans?

So, how might this relate to humans?

For starters, humans have a klotho gene almost identical to that in mice. Studies have shown that natural alterations of the klotho gene in both humans and mice can cause increased aging-related problems, such as muscular atrophy and hardening of the arteries.

"It makes for the intriguing possibility that the things found in mice [both good and bad] will also prove relevant to people," said Hal Dietz, professor of genetics at the Johns Hopkins University School of Medicine in Baltimore.

Now that the new study has shown that boosting klotho can generate longer mouse life spans, could humans benefit as well?

"I believe that the klotho gene can also regulate human aging," Kuro-O cautions. "So of course the immediate speculation would be that we could inject humans with klotho protein and extend human life span.

"But we just don't know," Kuro-O adds. "It might someday be an option for the treatment of aging. ... "

Klotho is likely an important key to how humans age, but not a single regulator. The gene is tied to some age-related afflictions. But it has not been linked to others, such as cancer or Alzheimer's disease.

"I don't think that klotho will turn out to be a master control gene for aging," Dietz, the Johns Hopkins geneticist, said.

"But I do think that klotho is clearly a regulator of many phenotypes [gene-related observable traits] that are associated with aging and that we'd like to alter," he said.

"If they could be manipulated, they would increase not only the length of life but the quality of life."

Body, Heal Thyself

Fifteen years ago scientists didn't even know that certain genes play a key role in regulating the aging process. But today scientists are using that knowedge to dramatically lengthen the life spans of worms, yeast cells—and now mice.

"We used to think of aging as if our bodies were cars that would wear out and break down," said pathologist David Sinclair of Harvard Medical School.

"But we now realize that, because we're biological organisms, we have cell-repair capacity, Sinclair said. "In every cell it's as if we have a mechanic who can be brought into action to slow the processes of deterioration and decay that lead to aging."

"We're just learning how to control those mechanics. The potential of the body to heal itself is huge."

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