The fountain of youth might be reserved to the annals of mythology, but geneticists may have just discovered the next closest thing. Their discovery could soon make it possible to extend the normal human lifespan to 500 years, according to the Buck Institute, a research group that studies aging.
During a series of simple genetic experiments on C. Elegans nematode worms, researchers found that they could extend the worms' lives by a shocking five times, far exceeding hypothesis expectations.
"Basically these worms lived to the human equivalent of 400 to 500 years," explained lead scientist Pankaj Kapahi.
Kapahi and colleagues combined mutations in two genetic pathways already known for lifespan extension. The first tweak involved mutations that inhibit key molecules involved in insulin signaling (IIS), which is usually associated with a doubling of the lifespan in these worms. A second tweak was performed on the nutrient signaling pathway Target of Rapamycin (TOR), which is typically associated with a 30 percent increase in lifespan.
Naturally, the researchers hypothesized that the dual tweak would combine for roughly a 130 percent lifespan extension. They were stunned when the worms showed a five-fold increase instead.
"Instead, what we have here is a synergistic five-fold increase in lifespan," said Kapahi. "The two mutations set off a positive feedback loop in specific tissues that amplified lifespan."
Kapahi also said it ought to be possible to use this method to combat many of the ailments of aging in more complex organisms too, possibly even humans. At the very least, the research could help explain why scientists are having a difficult time identifying single genes responsible for the long lives experienced by human centenarians.
"It's quite probable that interactions between genes are critical in those fortunate enough to live very long, healthy lives," said Kapahi.
The results are also encouraging because they found that the positive feedback loop originated in the germline tissue, which are sequences of reproductive cells that can be passed on to successive generations. If this is indeed the case, then it lends credence to the idea that a similar synergy between the two pathways might exist in more complex organisms.
Whether similar gene tweaks in humans would show the same results has yet to be tested, but there's reason for optimism. Researchers are already streamlining the experiment for trials on mice.
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