Abstract
53BP1 is a mediator of DNA double-strand break response including DNA damage checkpoint and DNA repair. Previously, we identified 53BP1 as a protein binding to tumor suppressor p53, but it is not clear whether 53BP1 is involved in p53 function. To elucidate this, we analyzed activation of p53 after X-irradiation using human cancer cell lines with functional p53, in which 53BP1 were depleted by RNAi. The result exhibited that depletion of 53BP1 down-regulated p53 activation but not ATM activation. Thus, our data indicate that 53BP1 functions upstream of p53 and downstream of ATM in the signaling pathway of p53 activation.
