Early embryonic lethality in PARP-1 Atm double-mutant mice suggests a functional synergy in cell proliferation during development

PARP-1 and ATM are bath involved in the response to DNA strand breaks, resu lting in induction of a signaling network responsible for DNA surveillance, cellular recovery, and cell survival. ATM interacts with double-strand bre ak repair pathways and induces signals resulting in the control of the cell cycle-coupled checkpoints. PARP-1 acts as a DNA break sensor in the base e xcision repair pathway of DNA. Mice with mutations inactivating either prot ein show radiosensitivity and high radiation-induced chromosomal aberration frequencies. Embryos carrying double mutations of both PARP-1 and ATM gene s were generated, These mutant embryos show apoptosis in the embryo but not in extraembryonic tissues and die at embryonic day 8.0, although extraembr yonic tissues appear normal for up to 10.5 days of gestation. These results reveal a functional synergy between PARP-1 and ATM during a period of embr yokenesis embryokenesis when cell cycle checkpoints are not active and the embryo is particularly sensitive to DNA. damage. These results suggest that ATM and PARP-1 have synergistic phenotypes due to the effects of these pro teins on signaling DNA damage and/or on distinct pathways of DNA repair.