Disabling de novo DNA methylation in embryonic stem cells allows an illegitimate fate trajectory

Masaki Kinoshita, Meng Amy Li, Michael Barber, William Mansfield, Sabine Dietmann, Austin Smith

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Genome remethylation is essential for mammalian development but specific reasons are unclear. Here we examined embryonic stem (ES) cell fate in the absence of de novo DNA methyltransferases. We observed that ES cells deficient for both Dnmt3a and Dnmt3b are rapidly eliminated from chimeras. On further investigation we found that in vivo and in vitro the formative pluripotency transition is derailed toward production of trophoblast. This aberrant trajectory is associated with failure to suppress activation of Ascl2. Ascl2 encodes a bHLH transcription factor expressed in the placenta. Misexpression of Ascl2 in ES cells provokes transdifferentiation to trophoblast-like cells. Conversely, Ascl2 deletion rescues formative transition of Dnmt3a/b mutants and improves contribution to chimeric epiblast. Thus, de novo DNA methylation safeguards against ectopic activation of Ascl2. However, Dnmt3a/b-deficient cells remain defective in ongoing embryogenesis. We surmise that multiple developmental transitions may be secured by DNA methylation silencing potentially disruptive genes.

Original languageEnglish
Article numbere2109475118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number38
StatePublished - Sep 21 2021


  • DNA methylation
  • Embryonic stem cells
  • Pluripotency


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