DNA repair is essential for cell vitality, cell survival, and cancer prevention, yet cells’ ability to patch up damaged DNA declines with age for reasons not fully understood.

Now, research led by scientists at Harvard Medical School (HMS) reveals a critical step in a molecular chain of events that allows cells to mend their broken DNA.

The findings, to be published March 24 in Science, offer a critical insight into how and why the body’s ability to fix DNA dwindles over time and point to a previously unknown role for the signaling molecule NAD as a key regulator of protein-to-protein interactions in DNA repair. NAD, identified a century ago, is already known for its role…