Epigenetic control of cell fate in mouse blastocysts: the role of covalent histone modifications and chromatin remodeling.

The first cell-fate decision in mammalian preimplantation embryos is the segregation of the inner cell mass (ICM) and trophectoderm (TE) cell lineages. The ICM develops into the embryo proper, whereas the TE ensures embryo implantation and is the source of the extra-embryonic trophoblast cell lineages, which contribute to the functional components of the placenta. The development of a totipotent zygote into a multi-lineage blastocyst is associated with the generation of distinct transcriptional programs. Several key transcription factors participate in the ICM and TE-specific transcriptional networks, and recent studies indicate that post-translational histone modifications as well as ATP-dependent chromatin remodeling complexes converge with these transcriptional networks to regulate ICM and TE lineage specification. This review will discuss our current understanding and future perspectives related to transcriptional and epigenetic regulatory mechanisms that are implicated in the initial mammalian lineage commitment steps, with a focus on events in mice.