No one is going to live forever, and there's nothing we can do about it. Every living thing has a sell-by date. However, it may be possible to increase our time on this planet, or at least make our old age healthier by discovering, understanding, and manipulating longevity genes.
The search for immortality is not quite as old as time itself, but for millennia humans have been concocting potions to try and hang around for as long as possible. And ever since the discovery of DNA there has been a belief that there may be a gene that contributes to a long life trait, that science will find this longevity gene and that it can be introduced into people who do not possess the trait naturally. The reality will be a little more complex as there will be several genes that contribute to a number of factors that influence lifespan, and these factors will be subject to many environmental influences, such as diet and stress.
Nonetheless the discovery of so-called longevity genes could lead to a slowing down of the ageing process, and better treatments for age-related diseases.
Examples of longevity genes: -
FOX03A - a variation of this gene is believed to be found more often in people living to 100 years and beyond. In research coming out of Kiel University in Germany (they have access to a large collection of DNA samples from very elderly people) the scientists confirmed this assumption by comparing the DNA from 388 German centenarians with the DNA from 731 younger people. In addition, this variation has been observed in centenarians all over the world. In previous work by an American research team led by Bradley J. Willcox, this same variation was found in Americans of Japanese origin who were aged over 95. So if there is a connection between a variation in this gene and living longer, what can it be? How does the gene influence the cellular environment to keep its owner alive for longer?
SIR2 - in yeast and other laboratory organisms scientists have found several longevity genes including daf-2, pit-1, and SIR2. They increase an organism's ability to survive extreme environmental conditions such as heat and drought. If these genes stay active for a long while it appears that they also improve health and extend lifespan. Restricting calorie intake has long been thought of as a way of increasing lifespan, and some scientists think that this is an environmental stressor that could activate SIR2. It has also been shown that an extra copy of SIR2 has increased longevity in several creatures such as yeast and fruit flies.
- Twenty five longevity genes were discovered by scientists at Washington University and other institutions in 2008. They were found in yeast and the roundworm C.elegans, and at least 15 of these genes have similar human versions. Some of the longevity genes play key roles in a nutrient response pathway known as TOR - Target of Rapamycin. The research lends weight to the idea that calorie intake affects lifespan by altering TOR activity.
Longevity Genes and Gene Therapy
The knowledge gleaned from discovering longevity genes could be applied in a number of ways.
Gene therapy to try an induce the effects of longevity genes
- Designing therapeutics to replicate the effects of longevity genes
- Understanding the optimum conditions for those genes to operate effectively. Those conditions could be a low stress, high nutrition diet. Or even a nutrient reduced diet.
Whether any of this is successful or not remains to be seen, but one application of longevity genes could be to increase the quality of life rather than its length. In August 2009 researchers at the University of Missouri published a paper detailing how they used gene therapy to introduce a longevity gene - MCAT - into mice. They found that the animals that had undergone the procedure could run faster, and for longer, than normal animals of the same age and sex. The scientists behind the study believe that the gene removes toxic substances called free radicals from the mitochondria. They postulate that a similar gene therapy approach in humans could be of benefit to people with muscular dystrophy and heart disease, as well as improving the health of the elderly.