The Role of Nucleosomes in Epigenetic Gene Regulation

Chromatin is a dynamic and highly organised structure that plays a role in all aspects of chromatin biology and controls access to DNA. The basic repeating unit of chromatin is the nucleosome, an octamer of histone proteins wrapped around twice with DNA. Transcriptional gene regulation is largely controlled by the epigenetic regulation of the nucleosome, both through the position of the nucleosome in the DNA and chemical modifications to the histone proteins within the nucleosome core. In this chapter, we discuss the role of the nucleosome in controlling gene regulation at promoters, enhancers and in gene bodies. We also discuss the role of bivalent chromatin and asymmetric nucleosomes at these elements. While the focus of this chapter is on transcriptional regulation, many of the concepts also extend to other aspects of chromatin biology including DNA repair and replication.