The same mechanism that causes children with a rare genetic disease called progeria to age at seven times the normal rate may play a role in normal ageing as well, US government researchers said.
The study led by Dr Francis Collins, director of the National Institutes of Health, suggests ageing may not simply be a gradual wearing out of cells.
Instead, it may be an active biological mechanism, one that might be tinkered with to address age-related diseases.
"I think a lot of people in the past have assumed that the ageing of cells and of individuals was just a matter of everything running down," said Dr Collins.
"What we are learning at the cellular level ... is that is not right," said Dr Collins, whose study appears in the Journal of Clinical Investigation.
Much of recent research into the biological processes of ageing has focused on telomeres, which Collins likens to "the aglets on shoelaces that keep the laces from them from getting ratty."
When telomeres become too short and frayed through cell division, the cell eventually dies. But it has not been entirely clear how this comes about.
Based on the study by Dr Collins and colleagues at the National Human Genome Research Institute, it now appears that the same toxic protein that drives the premature ageing disorder progeria plays a key role in normal cell ageing.
Formally known as known as Hutchinson-Gilford Progeria Syndrome, progeria is an extremely rare disease in which children experience symptoms normally linked with old age, hair loss, wrinkled skin, clogged arteries and arthritis. Affected children often die by the age of 13.
In a 2003 study, Dr Collins and colleagues found the disease is caused by mutations in a gene called LMNA that makes the toxic protein progerin.
"What this paper does is show the process that is happening in those children is clearly an important process in normal ageing," Dr Collins said. "And it shows the telomeres and progerin are connected. They have been on parallel scientific pathways and we have now found they are actually linked together."
He said when telomeres become too short and frayed, this triggers the production of progerin, signalling to the body that the cell is at the end of its useful life.
Dr Collins says the study shows that instead of being a passive wearing out of cells, ageing is an active biological mechanism that is programmed into cells.
And understanding this mechanism could lead to new kinds of treatments. Already, a study is underway in children with progeria to see if researchers could block the excess production of progerin.
Dr Collins says more work is needed to understand the biological mechanism of ageing.
"We clearly don't have the whole picture," he said.
But understanding the ageing process could lead to new ways to slow normal ageing, and it underscores the need to continue funding research on rare diseases.
"It is often the insights that come from the rare diseases that teach us something about more common ones," he said.
(Reuters Health, Julie Steenhuysen, June 2011)
Genetics - cancer & DNA