Replication-coupled passive DNA demethylation for the erasure of genome imprints in mice

Genome-wide DNA demethylation, including the erasure of genome imprints, in primordial germ cells (PGCs), is critical as a first step for creating the totipotent epigenome in the germ line. Here, we provide evidence that contrary to the prevailing model involving active DNA demethylation, imprint erasure in mouse PGCs occurs in a manner consistent with replication-coupled passive DNA demethylation: PGCs erase imprints during their rapid proliferation with little de novo as well as maintenance DNA methylation potential and no major chromatin alterations. Our findings necessitate the re-evaluation of and provide novel insights into the mechanism of genome-wide DNA demethylation in PGCs.

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Kagiwada S, Kurimoto K, Hirota T, Yamaji M, Saitou M