We have known for decades that physical activity weakens muscles. The question was always why. A new study from Duke-NUS Medical School in Singapore, published in the leading journal in the field, provides an answer at the molecular level: a single gene called DEAF1 increases with age and disrupts the balance between creating new proteins and eliminating damaged ones. The sport lowers it, and returns the cell to a youthful function.
The problem: more production, less cleaning
At the heart of the process is a cellular pathway called mTORC1, which is responsible for two parallel things: building new proteins, and removing the damaged ones (autophagy). In a young muscle the two are balanced. In old muscle, mTORC1 becomes unhealthy overactive. He continues to build, but stops cleaning.
The result: damaged proteins accumulate in the cell. They take up space, interfere with the mechanisms, and eventually the cell weakens. This is the process that produces the decrease in muscle strength, sarcopenia, and the loss of muscle mass with age.
The Discovery: Who Overactivates mTORC1?
The team led by Prof\' Tang Hong-wen from the Cancer and Stem Cell Program at Duke-NUS searched for the culprit. After a series of experiments on old mice and human cells, they identified it: a gene called DEAF1. DEAF1 levels increase with age in muscle. And as it rises, mTORC1 races. The proteins accumulate. The muscle is weakened.
"Exercise manages to reverse this process and correct the imbalance," explained Prof. Tang. "The activity activates proteins that lower DEAF1 levels, and return the growth pathway to a normal balance."
How does exercise knock down DEAF1?
The team followed the molecular chain. When the muscle contracts during training, it activates sensors that detect the mechanical load. These, in turn, activate enzymes that suppress DEAF1 expression. Within hours of exercise, muscle DEAF1 levels decrease. mTORC1 returns to a normal rate. The elimination of the damaged proteins is renewed.
What surprised the team: Even in very old mice, when DEAF1 was genetically removed, the muscles showed signs of regeneration. Grip strength improved, muscle mass increased, and damaged fibers were replaced with healthy fibers. That is, even without physical activity, a decrease in DEAF1 alone was enough to give an effect "as if we were exercising".
Meaning: drug that simulates exercise?
The discovery opens up three practical possibilities:
- A new medicinal target. A specific DEAF1 inhibitor could be a drug candidate for sarcopenia and muscle wasting in adults who cannot exercise (post-surgery, chronically ill, bedridden).
- Biomarker for muscle health. DEAF1 levels in a muscle biopsy may be used to estimate the biological age of the tissue.
- Improving training protocols. If we know what type of exercise lowers DEAF1 the most (aerobic? strength? HIIT?), we can make specific recommendations for adults.
Why is this more important than previous studies
We have had hints in the past about the connection between physical activity and cellular pathways. But DEAF1 is the first gene that explains the entire chain from contraction to protein renewal. He answers the question "What exactly happens in the molecule when I exercise?" with a clear answer.
What can you do now
- Resistance training 2-3 times a week remains the most powerful intervention against DEAF1.
- Incremental training is better than "every few days". DEAF1 levels rise again within 48-72 hours, so there is an advantage to frequency.
- Combination with sufficient protein (1.2-1.6 grams per kg of body weight per day at age 60+) intensifies the effect.
Until a DEAF1 inhibitor drug reaches the market (you can expect 5-7 years), the surest way to lower this gene is the simplest: get out of your chair and exercise.
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