Mice Engineered to Lack Muscle Contraction Gene Have Superior Endurance (and Humans Might, Too)

By Rebecca Boyle Posted 07.18.2011 at 3:39 pm 11 Comments

Fast Hamster Wikimedia Commons

Around mile 10 of a recent half marathon, my quadriceps started to tighten and my feet increasingly felt like lead. Along with improving my training, perhaps in the future I will use zinc-finger nuclease scissors to snip out a gene called IL-15Rα, so I can run long distances with ease.

Mice that lack this gene, which is related to muscle contraction, can run much farther than their counterparts, a new study says — suggesting a genetic predisposition to endurance in some athletes.

Physiologists led by Tejvir Khurana at the University of Pennsylvania were studying IL-15Rα, which had been linked to proteins associated with muscle contraction. They engineered mice to lack that gene, and recorded the mice’s activity. Every night, the knockout mice ran six times farther than normal mice, according to the Science NOW blog.

The team dissected the muscles in these marathon mice, and found the muscles had more fibers and more mitochondria, the power plants of cells, Science NOW reports. This meant the muscles took longer to tire and longer to use up their energy supplies. The researchers found that the lack of IL-15Rα coaxed one type of muscle cell to turn into another type — from fast-twitch, easily tired muscles into slower-contracting, longer-endurance muscles.

It turns out that endurance athletes also have IL-15Rα variations, which might help explain their stamina. Khurana et. al worked with some Australian researchers to study genetic samples from Olympians and other world-class athletes, and found certain genetic variants were more common in long-distance athletes than in sprinters, for instance.

The research is reported in the Journal of Clinical Investigation.

More work must be done to explain why the IL-15Rα knockout mice had such a proclivity for physical activity — no one coaxed them to run six times longer than their friends, they just did. So it’s not clear whether a lack of IL-15Rα made them hyperactive as well as tenacious. But “the work raises the possibility that drugs blocking IL-15Rα could one day enhance endurance,” Science NOW reports.

Until then, looks like I will just have to keep training.

[AAAS Science NOW]

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11 Comments

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extremechiton

07/18/11 at 4:53 pm

steroids will do the same thing.

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Sweepya

07/18/11 at 5:37 pm

Looks like a dwarf hamster..

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tcolguin

07/18/11 at 6:04 pm

Everything comes at a cost.

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BubbaGump

07/18/11 at 6:33 pm

He represents our political system and leaders as they decide our financial future and budget.

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aarontco

07/18/11 at 7:53 pm

Does this gene therapy also allow them to sing, "Here I come to save the day", or say "Andale! Andale! Arriba! Arriba!"?

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SAWolf

07/18/11 at 10:21 pm

Steroids will not induce the development of type I muscle mass which is the muscle type with the abundance of mitochondria, where the electron transport process occurs, the final step in the synthesis of ATP and where oxygen is the final electron acceptor generating the oxygen radicals which induce cellular damage.

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crackkills

07/19/11 at 8:26 am

@BubbaGump - This is the second article I have read today with your useless comments about how the topic of the article represents the government deciding our financial future. If you are dissatisfied with the government, go post your dribble on a government opinion blog. This is not the place for those statements, unless of course the article is referring to the government deciding our financial future.

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lanredneck

from Northfield, Vt

07/19/11 at 8:34 am

how much and when lol would love to get some of this, could you target certain muscle groups ak legs back and core? While keeping upper body with the quick reflex muscles?

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Geawiel

07/19/11 at 11:25 am

The big question is, do the mice that are good in endurance sacrafice burst speed/sprint speed for their endurance.

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rettaH_daM

07/19/11 at 11:35 am

Brain: Are you pondering what I'm pondering?

Pinky: Sure, Brain, but before we can enter the Boston Marathon, we must first complete a standard marathon course certified by a national governing body affiliated with the International Association of Athletics Federations within a certain period of time before the date of the desired Boston Marathon, usually within approximately 18 months prior.

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Pooua

07/21/11 at 3:12 pm

I'm sure there is a trade-off for not having the gene. I wonder what it might be? Strength?

I believe I inherited faster-than-average reflexes from my mom's side of the family. On a good day, I can respond about 10% faster than other people do, but I usually run around 5% faster. I suspect I have a higher ratio of fast-twitch to slow-twitch muscles, as many swimmers do. Unfortunately, I suffer from a lot of tendon inflammation. I am fighting inflammatory diseases, something else I apparently inherited from my mom's side of the family. Even at my peak, under constant physical training, I've never had much stamina. I'm in pain a lot of the time. I've suspected for a while there is a genetic component to these symptoms. Perhaps this research is in that direction?