THE quest to understand ageing has has been given a boost with the discovery that a gene that extends lifespan in yeast and worms may have the same effect in humans.
The gene, sirtuin 3, encodes a protein found in mitochondria, the energy factories of the cell. This fits in with the theory that ageing is at least partly due to accumulated damage from the highly reactive free radicals produced in mitochondria.
Up to a quarter of the variation in human lifespan is thought to be due to heredity, and several genes have been linked to longevity in animals. The latest study, led by Giovanna De Benedictis, a geneticist at the University of Calabria in Arcavata di Rende, Italy, shows that the sirtuin 3 gene is also associated with human longevity. 鈥淭he important message is that pathways that control ageing and longevity are conserved across evolution,鈥� De Benedictis says.
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Her team analysed variation in the sirtuin 3 gene in 801 local people, 120 of whom were centenarians. They found that the older men 鈥� though not women 鈥� were significantly more likely than younger people to have two copies of one variant of the gene, suggesting that this variant is linked with a survival advantage.
While other genes correlate with longevity in humans, many of them seem to be disease-susceptibility genes such as ApoE, which is linked with Alzheimer鈥檚 disease. These tell us little about ageing, because if one gene variant gives you a fatal disease its alternative form is bound to be more common in older people.
Sirtuin 3, in contrast, is not known to be linked to any disease, so the Italian team鈥檚 findings shed light on the basic biology of ageing, says Thomas Perls, a longevity researcher at Boston University. The results will appear later in Experimental Gerontology.