The findings could eventually help scientists combat muscle wasting due to aging and other causes.
Previous research has indicated that Sestrin tends to build up in muscles after a workout, although the role of this protein had never been fully understood. Help may be on its way, however, as new research indicates that an existing protein provides some of the key benefits of exercise.
Medicine researchers at the University of MI studying a class of naturally occurring protein called Sestrin have found that it can mimic many effects of exercise in flies and mice.
The beneficial effects of Sestrin include more than just improved endurance.
Taking advantage of Drosophila flies' normal instinct to climb up and out of a test tube, their collaborators from Wayne State University in the USA developed a type of fly treadmill.
When they compared the results from both fly batches, they found that the normal flies' ability to run around improved over a period by four to six hours, while the flies without Sestrin did not make any progress without exercise.
"Flies can usually run around four to six hours at this point and the normal flies' abilities improved over that period".
When mice that were bred to lack Sestrin exercised, there were none of the expected improvements in aerobic capacity, respiration, and the ability to burn fat.
When the researchers overexpressed Sestrin in the muscles of normal flies, essentially maxing out their Sestrin levels, they found those flies had abilities above and beyond the trained flies, even without exercise. In contrast, the flies that lacked Sestrin showed no improvement at all, suggesting that the molecule must in some way generate changes in endurance levels following exercise.
"We propose that Sestrin can coordinate these biological activities by turning on or off different metabolic pathways", says U Michigan's Prof. Prof. Myungjin Kim. "This kind of combined effect is important for producing exercise's effects".
Could Sestrin supplements be on the horizon? "Sestrins are not small molecules, but we are working to find small molecule modulators of Sestrin". Because these flies couldn't produce any more Sestrin than they started with, the researchers were unsurprised to see that the insects made no further gains after exercise.