mTOR

A protein that acts as the cell's central nutrient sensor, steering it toward growth when resources are plentiful and repair when scarce.

• Amino acids, insulin and energy status activate mTOR, which drives protein synthesis and growth and suppresses autophagy.
• Turning it down with the drug rapamycin extends lifespan in yeast, worms, flies and mice, even when mice start it late in life.
• Rapamycin is already approved to prevent transplant rejection; low or intermittent doses are being tested against ageing.
• Side effects include immune suppression and blood-sugar changes, and there is no proof yet that it slows ageing in people.