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Lowering the expression of a single gene may help extend the average human lifespan by 16 years, new research suggests.

Researchers 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. They found that reducing the expression of this gene extended the average lifespan on mice by 20 percent.

Researchers found that the lowering the expression of the gene did not affect every tissue and organ the same way.  For instance, experimental mice retained better memory and balance as they aged. However, their bones deteriorated more quickly than normal.

"While the high extension in lifespan is noteworthy, this study reinforces an important facet of aging; it is not uniform," lead researcher Toren Finkel, M.D., Ph.D., at NIH's National Heart, Lung, and Blood Institute (NHLBI), said in a news release. "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."

Researchers hope the latest findings will provide insight into the development of therapies for aging-related diseases that target specific organs. However, researchers say more studies are needed to identify exactly how aging in these different tissues is connected at the molecular level.

In the latest study, researchers engineered mice that produced about 25 percent of the normal amount of the mTOR protein, or about the minimum needed for survival.

The findings revealed that the median lifespan for the mTOR mice was 28.0 months for males and 31.5 months for females, compared to 22.9 months and 26.5 months for normal males and females. Researchers said that the lifespan increase in the study is one of the largest observed in mice so far.

While genetically modified mTOR mice aged better overall, researchers said they showed only selective improvement in specific organs.  Experimental mice outperformed normal mice of equivalent age in maze and balance tests, indicating better retention of memory or coordination. While older mTOR mice also retained more muscle strength and posture, they had a greater loss in bone volume and were more susceptible to infections, suggesting a loss of immune function.

The findings are published in the journal Cell Reports.