Functional Interactions of PARP-1 with p53 in Apoptotic Cells

As indicated above, we, and others, have recendy shown the molecular association of p53 with PARP-1 in apoptotic cells following DNA damage. Interestingly however, the covalent poly(ADP-ribosyl)ation of p53 in apoptotic cells only takes place under specific conditions, e.g., when PARP-1 has not yet been proteolyzed by apoptotic caspases 3 and/or 7. Thus, it appears that the functional interactions between these two DNA stiand-break-sensing polypeptides occur under well-defined conditions. 

For example, if the end-goal of a severely DNA-damaged cell is to commit suicide, the covalent poly(ADP-ribosyl)ation of p53 may not occur in order to facilitate the p53-dependent pathway of apoptosis. On the other hand, if the main physiological response of a cell is to survive, p53 may be modified with ADP-ribose polymers to avoid cell death, while DNA-repair 

Functional R uladon of p53 by Covalent Poly(ADP-Ribosyl)ation 

---