Reversible Histone Acetylation During Preimplantation Embryo Development in Mammals.

Histone acetylation is an epigenetic modification responsible for changes in chromatin architecture, accessibility, and ultimately gene expression. At the onset of a new life, when the fully differentiated parental genomes fuse together to generate a new totipotent cell, the gametes' epigenetic program must be erased, and new ones are progressively installed. Together with other epigenetic modifications, histone acetylation participates in the early events of embryogenesis, undergoing dynamic changes that involve several amino acid residues on different histone proteins. By analyzing studies that followed these changes during the preimplantation development in different mammals, we identified critical windows of acetylation/deacetylation in relation to the oocyte-to-zygote transition, the activation of the embryonic genome, and the specification of cell lineages, all crucial events for early embryo development, the establishment of pluripotent embryonic tissue, and ultimately of a multicellular organism.Finally, this survey points out the possibility that while contributing to the necessary plasticity of the embryonic stem cells, the reversibility of histone acetylation/deacetylation patterns renders this mechanism prone to be hijacked by environmental conditions, such as maternal diet or pollutants, leading to the alterations of epigenetic marks that can be potentially transmitted to the daughter cells and up to adulthood.