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p53-Independent apoptosis disrupts early organogenesis in embryos lacking both ataxia-telangiectasia mutated and Prkdc.

Titlep53-Independent apoptosis disrupts early organogenesis in embryos lacking both ataxia-telangiectasia mutated and Prkdc.
Publication TypeJournal Article
Year of Publication2006
AuthorsGladdy RA, Nutter LMJ, Kunath T, Danska JS, Guidos CJ
JournalMol Cancer Res
Date Published2006 May
KeywordsAnimals, Apoptosis, Ataxia Telangiectasia Mutated Proteins, Cell Cycle Proteins, DNA-Activated Protein Kinase, DNA-Binding Proteins, Embryonic Development, Female, Genes, p53, Immunohistochemistry, In Situ Nick-End Labeling, Male, Mice, Mice, SCID, Nuclear Proteins, Organogenesis, Protein-Serine-Threonine Kinases, Tumor Suppressor Protein p53, Tumor Suppressor Proteins

The ataxia-telangiectasia mutated (ATM) protein and the nonhomologous end-joining (NHEJ) pathway play crucial roles in sensing and repairing DNA double-strand breaks in postnatal cells. However, each pathway is dispensable for early embryogenesis. Loss of both ATM and Prkdc/Ku is synthetically lethal, but neither the developmental processes perturbed nor the mechanisms of lethality have been determined by previous reports. Here, we show that ATM and Prkdc collaborate to maintain genomic stability during gastrulation and early organogenesis, a period of rapid proliferation and hypersensitivity to DNA damage. At E7.5 to E8.5, ATM(-/-)Prkdcscid/scid embryos displayed normal proliferation indices but exhibited excessive apoptosis and elevated expression of Ser15-phosphorylated p53. Thus, this crucial regulatory residue of p53 can be phosphorylated in the absence of ATM or Prkdc. However, loss of p53 did not abrogate or delay embryonic lethality, revealing that apoptosis is p53 independent in these in ATM(-/-)Prkdcscid/scid embryos. Because mice with combined disruptions of ATM and other NHEJ components (ligase IV, Artemis) are viable, our data suggest a novel NHEJ-independent function for Prkdc/Ku that is required to complete early embryogenesis in the absence of ATM.

Alternate JournalMol. Cancer Res.
PubMed ID16687486