Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 103, Issue 26, Pages 10017-10022Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0602436103
Keywords
ataxia telangiectasia mutated; DNA double strand-break; tumorigenesis; neurogenesis; genomic instability
Categories
Funding
- NCI NIH HHS [P30 CA 21765, P30 CA021765, CA 21765] Funding Source: Medline
- NINDS NIH HHS [R01 NS037956, R56 NS037956, NS 37956] Funding Source: Medline
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The repair of DNA double-strand breaks (DSBs) occurs via nonhomologous end-joining (NHEJ) or homologous recombination (HR). These mechanistically distinct pathways are critical for maintenance of genomic integrity and organismal survival. Although inactivation of either pathway leads to embryonic lethality, here we show selective requirements for each DNA DSB repair pathway at different stages of mammalian nervous system development. DNA damage-induced apoptosis resulting from inactivation of HR (Xrcc2 deficiency) only occurred in proliferating neural precursor cells, whereas disruption of NHEJ (DNA ligase IV deficiency) mainly affected differentiating cells at later developmental stages. Therefore, these data suggest that NHEJ is dispensable for a substantial portion of early development because DSB repair during this period utilizes HR. Moreover, DNA damage-induced apoptosis required the ataxia telangiectasia mutated (Atm) kinase after disruption of NHEJ, but not HR, during neurogenesis. However, embryonic lethality arising from disruption of either repair pathway was rescued by loss of p53 and resulted in specific tumor types reflective of the particular DSB repair pathway inactivated. Thus, these data reveal distinct tissue- and cell-type requirements for each DNA DSB repair pathway during neural development and provide insights for understanding the contributions of DNA DSB responses to disease.
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