Basic Epigenetic Mechanisms and Phenomena

The term “epigenetics” literally defines mechanisms that act above genetics and was originally coined to describe processes that are essential to guide development from the fertilized oozyte to the mature offspring. Today, epigenetics is understood as mitotically/meiotically inherited information that is not dependent on DNA sequence. Epigenetic mechanisms are initiated in response to a factor or environmental signal and are stable even in the absence of the initial signal. Within the last two decades much progress has been made in the field owing to the discovery of proteins that are involved in setting and interpreting epigenetic marks. We can now appreciate epigenetic mechanisms that act on different layers of chromatin and their impact on development, differentiation, homeostasis, and also their causal involvement in a variety of diseases including cancer. This chapter will provide an introduction to basic epigenetic mechanisms and phenomena and discuss the role of epigenetics for different disease.