Exercise Lowers the Expression of the Gene That Drives Muscle Aging
For decades, researchers could describe what happens to muscle as a body ages. Strength fades, recovery from a stumble or a surgery drags on, and falls and fractures grow more likely. What they could not fully explain was the reason, the chain of events inside the cell that turns strong tissue into weak.
A team at Duke-NUS Medical School in Singapore, working with Singapore General Hospital and Cardiff University, has traced part of that chain to a single gene. Their findings, published in PNAS, put a protein called DEAF1 near the center of how muscle ages, and point to something ordinary that counters it: movement.
The trouble runs through a system inside muscle cells called mTORC1, which sets the balance between two constant jobs: assembling fresh proteins and disposing of worn-out ones. Young muscle keeps those two jobs even. In aging muscle, mTORC1 tips toward assembly and lets the disposal side lag, so worn proteins collect faster than they clear, and strength ebbs along with them.
DEAF1 is the lever behind that tilt. As muscle gets older, the team found, DEAF1 grows more abundant, and the more of it there is, the harder it drives mTORC1 out of balance. In a younger body, a family of proteins called FOXOs holds DEAF1 down. But FOXO activity fades with age too, releasing that restraint and letting DEAF1 build up with nothing to counter it.
Exercise, it turns out, is one of the things that naturally pushes DEAF1 back down. The team confirmed the link in two organisms as different as fruit flies and elderly mice, with the same outcome each time: when they forced DEAF1 up, muscle deteriorated faster; when they brought it down, strength recovered and the protein balance was restored.
“Exercise tells muscles to ‘clean up and reset,'” said Priscillia Choy Sze Mun, the study’s first author. “Lowering DEAF1 helps older muscles regain strength and balance, almost like hitting the rewind button.”
Senior author Tang Hong-Wen described the same loop from the pathway’s side. “Physical activity activates certain proteins which lower DEAF1 levels, bringing the growth pathway back into balance. This allows ageing muscles to clear out damaged proteins, rebuild themselves properly, and help them stay stronger and more resilient.”
There is a catch. Exercise only rights the imbalance while this control system still responds; once it stops responding, moving more may no longer be enough by itself. That ceiling is a big part of why the team is chasing DEAF1 as a drug target, separate from any advice about the gym. Plenty of people cannot move much, whether they are recovering from surgery, worn down by illness, or living in a body that has stopped answering the signals exercise sends. For them, a way to reach the same molecular switch by another route could matter a great deal.
That work is still ahead. For now, the study delivers something narrower and solid: a mechanism traced through flies and mice, and a sharper account of why the plain advice to keep moving holds up all the way down at the level of one gene. The body has been running this repair on its own the whole time. Researchers finally know the name of the switch it flips.
