Chapter 1-4 - Implications for Chromatin Biology in Toxicology

Abstract

A variety of early-life environmental exposures induce persistent epigenetic alterations, termed “epigenetic reprogramming,” which can cause changes in phenotype and disease susceptibility. It's becoming clear that phenotypic changes, such as congenital abnormalities, appearance, and behavior, may not present themselves after an initial insult, but instead, the initial insult induces epigenetic alterations that poise the genome to respond aberrantly to later-life challenges such as hormone exposure or dietary changes, culminating in increased risk of disease. Utilizing epigenomic alterations to identify individuals at increased disease risk is a current goal in the field, as is understanding the mechanisms responsible for epigenetic reprogramming. Understanding epigenetic reprogramming holds promise for the development of biomarkers of exposure and disease risk and new targets for interventions. Here, we describe mechanisms that contribute to epigenetic reprogramming of histone modifications in response to environmental exposures. Normal biological processes also involve changes in epigenetic histone modifications, including development and aging. Exploring epigenetic plasticity in normal physiological settings may also reveal how this plasticity creates a vulnerability to environmental exposures.