An operational definition of epigenetics

Abstract

A recent meeting (December 2008) regarding chromatin-based epigenetics was hosted by the Banbury Conference Center and Cold Spring Harbor Laboratory. The intent was to discuss aspects of epigenetic control of genomic function, and to arrive at a consensus definition of "epigenetics" to be considered by the broader community. It was evident that multiple mechanistic steps lead to the stable heritance of the epigenetic phenotype. Below we provide our view and interpretation of the proceedings at the meeting.

Figure 1.

The epigenetic pathway. Three categories of signals are proposed to operate in the establishment of a stably heritable epigenetic state. An extracellular signal referred to as the “Epigenator” (shown in blue) originates from the environment and can trigger the start of the epigenetic pathway. The “Epigenetic Initiator” (shown in red) receives the signal from the “Epigenator” and is capable of determining the precise chromatin location and/or DNA environment for the establishment of the epigenetic pathway. The “Epigenetic Maintainer” (shown in green) functions to sustain the chromatin environment in the initial and succeeding generations. Persistence of the chromatin milieu may require cooperation between the Initiator and the Maintainer. Examples for each category are shown below each heading. Chromatin is depicted in blue.