Researchers at the National Institutes of Health (NIH) have created genetically altered mice that outlive regular mice by about 20%--the equivalent of raising the average human lifespan by 16 years, from 79 to 95.
To engineer these longer-living mice, the investigators targeted and lowered the expression of a gene called mTOR--which is involved in metabolism and energy balance and may be linked to the increased lifespan associated with calorie restriction.
"While the high extension in lifespan is noteworthy, this study reinforces an important facet of aging; it is not uniform," said lead researcher Dr. Toren Finkel of NIH's National Heart, Lung, and Blood Institute (NHLBI), in a statement.
While altering this gene extended the lifespan of the mice, it did not affect every tissue and organ the same way. For example, as the mice aged, they retained better memory and balance, but their bones deteriorated more quickly than those of mice that were not genetically altered.
The engineered mice produced about 25% of the normal amount of the mTOR protein--about the minimum needed for survival. They were slightly smaller than average but otherwise appeared normal. Muscle strength and posture was better maintained in the genetically altered mice compared with regular mice, but they also showed a greater susceptibility to infections at old age, suggesting a loss of immune function. The findings appear in the Aug. 29 edition of Cell Reports.
The findings could help guide the development of new treatments for aging-related diseases like Alzheimer's, but more tests in mice as well as human cells are needed to identify how the aging process in various tissues is connected at the molecular level.
- read the press release
- here's the study summary