Checkpoint kinase-2 and p53 in human leukemic cells MOLT-4 after gamma irradiation

Abstract

Ionizing radiation causes activation of ATM-kinase, which further influences a number of downstream targets involved in cell-cycle regulation and apoptosis. We investigated the molecular pathway induced by gamma-irradiation in human leukemic cells MOLT-4.

Here we show that rapid phosphorylation of checkpoint kinas-2 (0.5 hour post irradiation)) precedes accumulation of protein p53 and its phosphorylation on serine 392 with subsequent induction of apoptosis. Oncoprotein Mdm2 (p53-negative regulator) is maximally phosphorylated at the same time as p53.