X chromosome reactivation initiates in nascent primordial germ cells in mice.
Sugimoto M, Abe K.
Technology and Development Team for Mammalian Cellular Dynamics, BioResource Center, RIKEN Tsukuba Institute, Tsukuba, Ibaraki, Japan.
During primordial germ cell (PGC) development, epigenetic reprogramming events represented by X chromosome reactivation and erasure of genomic imprinting are known to occur. Although precise timing is not given, X reactivation is thought to take place over a short period of time just before initiation of meiosis. Here, we show that the cessation of Xist expression commences in nascent PGCs, and re-expression of some X-linked genes begins in newly formed PGCs. The X reactivation process was not complete in E14.5 PGCs, indicating that X reactivation in developing PGCs occurs over a prolonged period. These results set the reactivation timing much earlier than previously thought and suggest that X reactivation may involve slow passive steps.
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PMID: 17676999 [PubMed - indexed for MEDLINE]PMCID: PMC1950944