Function for p300 and not CBP in the apoptotic response to DNA damage

The cellular response to ionizing radiation (IR) includes the induction of apoptosis, The p300/CBP proteins possess histone acetyltransferase activity and function as transcriptional coactivators of p53. We have prepared cell s deficient in p300 or CBP to define the roles of these proteins in the cel lular response to DNA damage, The present results demonstrate that p300, bu t not CBP, contributes to IR sensitivity of cells. The results also demonst rate that IR-induced apoptosis is impaired in the p300-, but not CBP-, defi cient cells. These findings indicate that p300 functions in the apoptotic r esponse to DNA damage.