Autophagy

Cells accumulate debris: misfolded proteins, worn-out mitochondria, bacterial invaders. Autophagy is the mechanism that clears them. The cell builds a double-membrane vesicle (autophagosome), engulfs the target, and fuses with a lysosome to break it down into reusable amino acids and lipids. The process runs at a low baseline rate and ramps sharply under stress — fasting, infection, or damage. When autophagy slows with age, the backlog compounds: aggregated proteins build up in neurons, damaged organelles accumulate, and cells lose the ability to adapt. Restoring flux is a live target in neurodegeneration and longevity research.