Epigenetics in Health and Disease

2. Chromatin dynamics and chromatin remodeling in animals

A proper function of eukaryotic cells requires the packaging of the long DNA chain into a small nucleus. In mammals, approximately 2 meters of DNA has to fit into the nucleus, which is about 5 micrometers in size. Even a more complex task is to package DNA so that it allows for the development- and tissue-specific expression pattern. Chromatin compaction is achieved through the activity of small basic proteins called histones. DNA is wrapped twice around the histone octamer, thus taking the basic unit of chromatin assembly—the nucleosome, which compacts the DNA length about sevenfold—from 2 nm to roughly 11 nm. The binding of histone H1 between two nucleosomes triggers further compaction ...