An "on/off" switch for aging cells

Scientists at the Salk Institute have discovered an on-and-off “switch” in cells that may hold the key to healthy aging. This switch points to a way to encourage healthy cells to keep dividing and generating, for example, new lung or liver tissue, even in old age.

In our bodies, newly divided cells constantly replenish lungs, skin, liver and other organs. However, most human cells cannot divide indefinitely–with each division, a cellular timekeeper at the ends of chromosomes shortens. When this timekeeper, called a telomere, becomes too short, cells can no longer divide, causing organs and tissues to degenerate, as often happens in old age. But there is a way around this countdown: some cells produce an enzyme called telomerase, which rebuilds telomeres and allows cells to divide indefinitely.

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