Deficiency in both ATM and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is synthetically lethal in developing mouse embryos. Using mice that phenocopy diverse aspects of Atm deficiency, we have analyzed the genetic requirements for embryonic lethality in the absence of functional DNA-PKcs. Similar to the loss of ATM, hypomorphic mutations of Mre11 (Mre11(ATLD1)) led to synthetic lethality when juxtaposed with DNA-PKcs deficiency (Prkdc(scid)). In contrast, the more moderate DNA double-strand break response defects associated with the Nbs1(DeltaB) allele permitted viability of some Nbs1(DeltaB/DeltaB) Prkdc(scid/scid) embryos. Cell cultures from Nbs1(DeltaB/DeltaB) Prkdc(scid/scid) embryos displayed severe defects, including premature senescence, mitotic aberrations, sensitivity to ionizing radiation, altered checkpoint responses, and increased chromosome instability. The known functions of DNA-PKcs in the regulation of Artemis nuclease activity or nonhomologous end joining-mediated repair do not appear to underlie the severe genetic interaction. Our results reveal a role for DNA-PKcs in the maintenance of S/G(2)-phase chromosome stability and in the induction of cell cycle checkpoint responses.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.