Artemis and nonhomologous end joining-independent influence of DNA-dependent protein kinase catalytic subunit on chromosome stability.
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.
Pubmed ID: 19015239 RIS Download
Animals | Ataxia Telangiectasia Mutated Proteins | Cell Cycle | Cell Cycle Proteins | Cell Death | Chromosomal Instability | Chromosomal Proteins, Non-Histone | DNA Breaks, Double-Stranded | DNA Repair | DNA Repair Enzymes | DNA-Activated Protein Kinase | DNA-Binding Proteins | Embryo, Mammalian | Endonucleases | G2 Phase | Mice | Mice, Transgenic | Nuclear Proteins | Protein-Serine-Threonine Kinases | S Phase | Tumor Suppressor Proteins