02 Sep 2013, BioSpectrum Bureau , BioSpectrum
Singapore: Researchers at the National Institutes of Health (NIH) have found that by lowering the expression of a single gene can extend the average lifespan of a group of mice by about 20 percent, which is equivalent of raising the average human lifespan by 16 years. This study has been published in Cell Reports.
The research team targeted a gene called mTOR, which is involved in metabolism and energy balance, and may be connected with the increased lifespan associated with caloric restriction. The researchers engineered mice that produce about 25 percent of the normal amount of the mTOR protein, or about the minimum needed for survival. The engineered mTOR mice were a bit smaller than average, but they otherwise appeared normal.
While the genetically modified mTOR mice aged better overall, they showed only selective improvement in specific organs. They generally outperformed normal mice of equivalent age in maze and balance tests, indicating better retention of memory and coordination. Older mTOR mice also retained more muscle strength and posture. However, mTOR mice had a greater loss in bone volume as they aged, and they were more susceptible to infections at old age, suggesting a loss of immune function.
Dr Toren Finkel, lead researcher, National Heart, Lung, and Blood Institute (NHLBI), NIH, said that, "While the high extension in lifespan is noteworthy, this study reinforces an important facet of aging; it is not uniform. Rather, similar to circadian rhythms, an animal might have several organ-specific aging clocks that generally work together to govern the aging of the whole organism."
In addition to the NHLBI, this study was carried out by intramural researchers at the NIH's National Cancer Institute; National Institute of Diabetes and Digestive and Kidney Diseases; and National Institute on Aging.