P. D Adams

An old house often has a locked cabinet full of tools: everything is there, but nobody fixes anything. Aging cells work much the same way. They accumulate the enzyme NAMPT, which kicks off production of the molecule NAD+, a sort of fuel for cellular processes. But in old cells that fuel is burned slowly, and the enzyme sits idle. NAMPT is the key that opens the door to NAD+.

In an orchestra that has been playing the same symphony for years, the musicians gradually start to drift: each one plays on their own, yet the notes remain the same. That is roughly what happens to cells as they age. Scientists have come up with a way to measure this discord, that is, how faithfully each cell follows the shared program of gene expression.