A piece from earlier this year at InfoAging: "Aging is characterized primarily by the decline of function in various cellular and molecular systems in the body. These changes are influenced by three factors: genetics, metabolism, and the environment. The focus in Dr. Cuervo's lab is the metabolic changes and resulting damage from these changes that are experienced with age, specifically damage to proteins. Every person experiences this damage to some degree, regardless of their age, but when it comes to repairing or removing the damage, the difference between young and old is clear. In younger people, the damaged or misfolded proteins can be repaired by what are known as chaperone proteins. Yet, like an old car, proteins that have undergone too much repair are not worth maintaining and so they are transported by the chaperone to the lysosome as 'trash' where they bind to a receptor and undergo autophagy (literally, self-eating) inside the organelle. Dr. Cuervo's research focuses on this pathway and how a major decline in its functionality is seen in older organisms." The piece goes on to describe how researchers restored this functionality to youthful levels in aged mice.