Longevity Research Raises Hopes, and Questions
Posted by Xeno on September 23, 2011
A trans-Atlantic dispute has opened up between two camps of researchers pursuing a gene that could lead to drugs that enhance longevity. British scientists say the longevity gene is “nearing the end of its life,” but the Americans whose work is under attack say the approach remains as promising as ever.
The dispute concerns genes that make sirtuins, proteins involved in controlling cells’ metabolism. Because of their metabolic role, the sirtuins may mediate the 40-percent-longer life enjoyed by laboratory rats and mice put on a very low-calorie diet.
People cannot keep to such a low-fat diet, but drugs that activate sirtuin would in principle be a painless way for humans to add years of lean and healthy life. This idea took wing when resveratrol, a substance found in trace quantities in red wine, was reported to activate sirtuin. In 2008 the pharmaceutical company GlaxoSmithKline paid $720 million for Sirtris, a start-up company trying to develop resveratrol-mimicking drugs that activate sirtuins.
Since then, several aspects of the sirtuin story have come under scientific challenge, including doubts as to whether resveratrol’s effects are really exercised through sirtuin, and whether the sirtuins are the real or only mediators of the longevity increase linked to a low-calorie diet.
Despite these concerns, the idea that sirtuins promote longevity appeals to scientists because of experiments that were started in yeast and repeated in two other standard laboratory organisms, the roundworm and the fruit fly.
It is these foundation experiments that have now come under attack by David Gems and Linda Partridge, researchers on aging at University College London. In an article published Wednesday in the journal Nature, they and colleagues have re-examined experiments in which roundworms and flies, genetically manipulated to produce more sirtuin than normal, were reported to live longer.
Both experiments were flawed, they say, because the worms and flies used as a control were not genetically identical to the test organisms. The London researchers report that they have repeated the experiments with proper controls and found that extra sirtuin does not, after all, make the worms or flies live longer. …