What mTOR is
mTOR (mechanistic, formerly mammalian, target of rapamycin) is a protein kinase that acts as a master sensor of nutrients and growth signals. When nutrients are plentiful it drives growth and protein synthesis; when they are scarce it switches on repair and recycling (autophagy).
Why it matters for longevity
Reducing mTOR signalling extends lifespan across yeast, worms, flies and mice. It is the pathway through which both caloric restriction and rapamycin are thought to act, making mTOR one of the most important nodes in ageing biology.
What the evidence shows
The animal and mechanistic evidence is strong and reproducible. In humans the picture is earlier-stage: mTOR inhibition is being tested for ageing-related endpoints, but no therapy is proven to extend healthy human lifespan via this pathway.
Related
See rapamycin and metformin for the drugs most associated with modulating nutrient-sensing pathways.