Epigenetics and psychoneuroimmunology: mechanisms and models

Abstract

In this Introduction to the Named Series "Epigenetics, Brain, Behavior, and Immunity" an overview of epigenetics is provided with a consideration of the nature of epigenetic regulation including DNA methylation, histone modification and chromatin re-modeling. Illustrative examples of recent scientific developments are highlighted to demonstrate the influence of epigenetics in areas of research relevant to those who investigate phenomena within the scientific discipline of psychoneuroimmunology. These examples are presented in order to provide a perspective on how epigenetic analysis will add insight into the molecular processes that connect the brain with behavior, neuroendocrine responsivity and immune outcome.

Figure 1. Epigenetic processes, DNA methylation and histone modification

DNA methylation is an epigenetic mark which often represses gene transcription. Histones are proteins around which DNA is packaged and histone modifications can either repress or enhance gene transcription. Histone modifications occur when epigenetic factors are bound to histone “tails” and alter the extent to which DNA is wrapped around the histones, thus, altering the availability of DNA for transcription. DNA methylation and histone modification can impact health and may contribute to disease states such as cancer, autoimmune manifestations, mental disorders, or diabetes (Selvi and Kundu, 2009). Epigenetic mechanisms are affected by several factors and processes including; development in utero and in childhood, environmental stress, drugs and pharmaceuticals, aging, and diet, http://nihroadmap.nih.gov/epigenomics/index.asp. A color image is available on line in supplemental materials. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation. This work is in the public domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the US Code. The website for this figure is as follows: http://commons.wikimedia.org/wiki/File:Epigenetic_mechanisms.jpg

Figure 2. Cross sectional ribbon diagram of a nucleosome with central histones, their amino terminal tails, with DNA wrapped about the exterior surface

A color image is available on line in supplemental materials. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation. The figure is by Richard Wheeler (Zephyris), Sir William Dunn School of Pathology, University of Oxford, UK.Permission for its use has been obtained from Richard Wheeler, Zephyris, at the English language Wikipedia, the copyright holder of this work. The website for this figure is as follows: http://en.wikipedia.org/wiki/File:Nucleosome_1KX5_colour_coded.png.