Targeted mutation of the DNA methyltransferase gene results in embryonic lethality

These results indicate that while a 3-fold reduction in levels of genomic m5C has no detectable effect on the viability or proliferation of embryonic stem cells in culture, a similar reduction of DNA methylation in embryos causes abnormal development and embryonic lethality

En Li; Timothy H. Bestor; Rudolf Jaenisch

2004

Key concepts

Scholarcy highlights

  • Gene targeting in embryonic stem cells has been used to mutate the murine DNA methyltransferase gene
  • ES cell lines homozygous for the mutation were generated by consecutive targeting of both wild-type alleles; the mutant cells were viable and showed no obvious abnormalities with respect to growth rate or morphology, and had only trace levels of DNA methyltransferase activity
  • A quantitative end-labeling assay showed that the level of m5C in the DNA of homozygous mutant cells was about one-third that of wild-type cells, and Southern blot analysis after cleavage of the DNA with a methylation-sensitive restriction endonuclease revealed substantial demethylation of endogenous retroviral DNA
  • The DNA of homozygous embryos showed a reduction of the level of m5C similar to that of homozygous ES cells
  • These results indicate that while a 3-fold reduction in levels of genomic m5C has no detectable effect on the viability or proliferation of ES cells in culture, a similar reduction of DNA methylation in embryos causes abnormal development and embryonic lethality
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