Ever wonder why some of the old buddies you see at your high school reunion look like they could be your parents? Or why, perhaps, you look like you could be theirs? Blame it on telomeres, caps at the end of your cells' chromosomes that appear to hold the key to aging.
This week researchers from the Dana-Farber Cancer Institute reported that the length of telomeres -- which shorten with age -- determines virtually every aspect of aging from wrinkles and gray hair to the onset of dementia, diabetes, and heart disease. At least that was the case in the mice they studied in a report published in Nature.
"We think we've identified the core pathway that really helps explain many different theories of aging," says study co-author Dr. Ronald DePinho, a geneticist at Dana-Farber. "Our study provides a unified field theory for aging."
In a nutshell, once telomeres shorten to a particular length, aging accelerates. Shortened telomeres allow the cell's DNA to become damaged, which activates a gene, p53. This sets off a warning to shut down the cells' normal growth and division cycle until the damage can be fixed or, if not, the cells die.
At the same time, cells with short telomeres have power plants, or mitochondria, that are no longer operating at full capacity. This leads to malfunction in crucial organs like the brain, heart, liver, and pancreas, as well as a loss of muscle, and eventually extreme weakness and frailty.
The cycle feeds itself, quickly accelerating, says DePinho. "We do really well for decades and then in the last few years of life, we have a precipitous decline in health."
While genes certainly play a role in how quickly telomeres shorten, research suggests that lifestyle factors may matter just as much. Dr. Dean Ornish,a researcher at the University of California, San Francisco, found several years ago that volunteers -- yes, humans -- who agreed to follow a low-fat diet, regular exercise, and relaxation techniques wound up increasing their levels of telomerase, an enzyme that maintains the length of telomeres.
Avoiding smoking and excess calories, DePinho says, can also help slow the aging process. Some folks have drastically cut their calorie intakes to as little as 1,200 calories a day after some calorie restriction studies in mice and monkeys found that the practice slowed the aging process. But DePinho says it's best just to try to avoid becoming overweight.
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