DNA methylation, histone deacetylase repressory complexes and development

DNA methylation in mammals is known to play a role in gene silencing and to be critical in embryo development. Here we describe how methylation makes use of histone deacetylase repressory complexes in stable gene silencing and perhaps also in stable inheritance of chromatin structure. If DNA methylation is an evolutionary more recent addition to the mechanisms regulating the mammalian genome, it certainly takes advantage of existing histone deacetylase repressory complexes that are observed in methylation deficient organisms, such as Drosophila, yeast, and C. elegans.