One of the most common cellular responses to DNA breakage is the covalent post-translational modification of the nuclear proteins with poly ADP ribose from the NAD+ as a precursor, which is mostly catalyzed by the poly-ADP-ribose polymerase1(PARP1).
A Review on: “Recent Updates on Poly-Adp-Ribosylation (Parylation) in Physiology and Pathology”
