Proliferation failure and gamma radiation sensitivity of Fen1 null mutant mice at the blastocyst stage

Mol Cell Biol. 2003 Aug;23(15):5346-53. doi: 10.1128/MCB.23.15.5346-5353.2003.

Abstract

Flap endonuclease 1 (FEN1) has been shown to remove 5' overhanging flap intermediates during base excision repair and to process the 5' ends of Okazaki fragments during lagging-strand DNA replication in vitro. To assess the in vivo role of the mammalian enzyme in repair and replication, we used a gene-targeting approach to generate mice lacking a functional Fen1 gene. Heterozygote animals appear normal, whereas complete depletion of FEN1 causes early embryonic lethality. Fen1(-/-) blastocysts fail to form inner cell mass during cellular outgrowth, and a complete inactivation of DNA synthesis in giant cells of blastocyst outgrowth was observed. Exposure of Fen1(-/-) blastocysts to gamma radiation caused extensive apoptosis, implying an essential role for FEN1 in the repair of radiation-induced DNA damage in vivo. Our data thus provide in vivo evidence for an essential function of FEN1 in DNA repair, as well as in DNA replication.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Apoptosis
  • Blastocyst / metabolism
  • Cell Division
  • DNA Repair
  • DNA Replication
  • Endodeoxyribonucleases / genetics*
  • Endodeoxyribonucleases / physiology*
  • Flap Endonucleases
  • Gamma Rays
  • Genetic Vectors
  • Genotype
  • Heterozygote
  • Homozygote
  • In Situ Nick-End Labeling
  • Mice
  • Mice, Transgenic
  • Microscopy, Fluorescence
  • Models, Genetic
  • Mutation
  • Oxidative Stress
  • Physical Chromosome Mapping
  • Polymerase Chain Reaction
  • Time Factors

Substances

  • Endodeoxyribonucleases
  • Flap Endonucleases