The missing link

Scientists ID protein that links dietary restriction with healthy aging

By Czerne M. Reid

Christiaan Leeuwenburgh/Photo by Sarah Kiewel

Restricting calories extends life and slows a range of age-related disorders in mice, rats and other organisms. But even after eight decades of research on the subject, scientists are still unclear just how caloric restriction exerts its age-battling influence.

Now, for the first time in mammals, UF researchers and colleagues at the University of Wisconsin have sleuthed out the role of a key player in the process, using age-related hearing loss as an example. The protein in question, called Sirt3, could provide a new target for anti-aging drug therapies. The findings were reported in the Nov. 24 issue of the journal Cell.

The researchers found that when Sirt3 is absent, caloric restriction loses its anti-aging powers. They uncovered details of how the protein, an enzyme found primarily in mitochondria — the energy-producing centers of cells — wards off cell death by maintaining an environment that combats destructive chemicals.

“Knocking it out seems to be very negative for mitochondrial function and allows the accumulation of oxidative stress and damage to neurons and other cells,” said Christiaan Leeuwenburgh, Ph.D., one of the study’s senior authors who is chief of the biology of aging division in the UF College of Medicine department of aging and geriatric research and a member of the UF Institute on Aging. “That’s an important clue about the role that Sirt3 plays in protecting cells from age-related damage.”

Age-related hearing loss is the most common sensory disorder among the elderly, affecting more than 40 percent of people older than 65 and projected to affect 28 million Americans by 2030, according to the Department of Health and Human Services.