Chromatin Regulation of Early Embryonic Lineage Specification

Anzy Miller, Brian Hendrich, Miller, Anzy, Hendrich, Brian

The very first cell divisions in mammalian embryogenesis produce a ball of cells, each with the potential to form any cell in the developing embryo or placenta. At some point, the embryo produces enough cells that some are located on the outside of the embryo, while others are completely surrounded by other cells. It is at this point that cells undergo the very first lineage commitment event: outer cells form the trophectoderm and lose the potential to form embryonic lineages, while inner cells form the Inner Cell Mass, which retain embryonic potential. Cell identity is defined by gene expression patterns, and gene expression is largely controlled by how the DNA is packaged into chromatin. A number of protein complexes exist which are able to use the energy of ATP to remodel chromatin: that is, to alter the nucleosome topology of chromatin. Here, we summarise the evidence that chromatin remodellers play essential roles in the successful completion of preimplantation development in mammals and describe recent efforts to understand the molecular mechanisms through which chromatin remodellers facilitate the successful completion of the first cell fate decisions in mammalian embryogenesis.