Identifying the machinery for epigenetic regulation at the dawn of metazoa

Epigenetics is the study of heritable differences in gene expression levels that are caused by mechanisms other than direct changes of the DNA sequence (Riggs et al. 1996). Many of those differences are the result of the actions of several classes of proteins that operate to modify the organization of DNA, including DNA methyltransferases (reviewed in Robertson 2005; Goll and Bestor 2005), histone acetylases (reviewed in Nakatani 2001) and deacetylases (reviewed in Lahue and Frizzell 2012), other histone modifiers (e.g. methylation reviewed in Black et al. 2012; ubiquitylation reviewed in Wright et al. 2012), and chromatin remodeling proteins (reviewed in Hargreaves and Crabtree 2011). These proteins interact with DNA in such a way as to change local chromatin states and gene expression patterns, thus influencing the phenotypes of the organism. Epigenetic regulation has been found to have implications in numerous human diseases, such as schizophrenia (Akbarian 2010), many types of cancer (Jones and Laird 1999; Laird 2005; Min et al. 2012; Heyn et al. 2012; Björkman et al. 2010), and Angelman syndrome (Zhao et al. 2007), and thus is an area of focused interest to both the scientific and medical communities