The precise genes involved in the control of ageing have been unclear, but several studies from invertebrates studies suggest that some of these life span genes encode components of the insulin or insulin-like signaling pathways. In December 5 Nature, Martin Holzenberger and colleagues at the INSERM, France, show that IGF-1 receptor regulates lifespan and resistance to oxidative stress in mice (Nature doi:10.1038/nature01298, December 5, 2002).

Holzenberger et al. inactivated the IGF-1R gene in mice (Igf1r) and observed that female Igf1r1/2 mice live 33% longer than wild-type females (P < 0.001), whereas the equivalent male mice show an increase in lifespan of 16% (which was not statistically significant). The long-lived Igf1r1/2 mice do not develop dwarfism, their energy metabolism is normal, and their nutrient uptake, physical activity, fertility and reproduction are unaffected. In addition, they showed that the Igf1r1/2 mice display greater resistance to oxidative stress —a factor commonly associated with the ageing process.

"These results show that a general decrease in IGF-1 receptor levels can increase lifespan in a mammalian species. Thus, the genetic link between insulin-like signaling and longevity, originally discovered in non-vertebrates, also seems to exist in higher vertebrates", conclude the authors.