Scientists find a key pathway for ageing

Scientists have discovered a molecular pathway that plays a determinant role in the process of ageing.

Washington: Scientists have discovered a molecular pathway that plays a determinant role in the process of ageing, a finding they say could lead to new drugs to treat ageing-related diseases.

Past studies have suggested that low-calorie diets can help slow the process of ageing and improve health in old age. But how it works has so far been a mystery.

Now, a team from the University of Wisconsin-Madison in the US found a molecular pathway which is a key determinant of the ageing process.

The finding, appeared online in the journal Cell, not only helps explain the cascade of events that contributes to ageing, but also provides a rational basis for devising interventions, drugs that may retard ageing and contribute to better health in old age, said the researchers.

"We`re getting closer and closer to a good understanding of how caloric restriction works," said senior author of the study Tomas A Prolla, a UW-Madison professor of genetics.

"This study is the first direct proof for a mechanism underlying the anti-ageing effects we observe under caloric restriction."

The new study focuses on an enzyme called Sirt3 – one of a family of enzymes known as sirtuins, which have been implicated in previous studies in the ageing process, gene transcription, programmed cell death and stress resistance under reduced calorie conditions.

In mammals, including humans, there are seven sirtuins that seem to have wide-ranging influence on cell fate and physiology.

Sirt3 has been less studied than other members of the sirtuin family, but the new study provides "the first clear evidence that sirtuins have anti-ageing effects in mammals," said study researcher John M Denu of UW-Madison`s Wisconsin Institute for Discovery.

The Sirt3 enzyme, Denu explained, acts on mitochondria -- structures inside cells that produce energy and that are the sources of highly reactive forms of oxygen known as free radicals, which damage cells and promote the effects of ageing.

Under reduced-calorie conditions, levels of Sirt3 amp up, altering metabolism and resulting in fewer free radicals produced by mitochondria.