ABSTRACT Epigenetics investigates heritable changes in gene expression that occur without changes in DNA sequence. Several epigenetic mechanisms, including DNA methylation and histone modifications, can change genome function under exogenous influence. We review current evidence indicating that epigenetic alterations mediate effects caused by exposure to environmental toxicants. Results obtained from animal models indicate that in utero or early-life environmental exposures produce effects that can be inherited transgenerationally and are accompanied by epigenetic alterations. The search for human equivalents of the epigenetic mechanisms identified in animal models is under way. Recent investigations have identified a number of environmental toxicants that cause altered methylation of human repetitive elements or genes. Some exposures can alter epigenetic states and the same and/or similar epigenetic alterations can be found in patients with the disease of concern. On the basis of current evidence, we propose possible models for the interplay between environmental exposures and the human epigenome. Several investigations have examined the relationship between exposure to environmental chemicals and epigenetics, and have identified toxicants that modify epigenetic states. Whether environmental exposures have transgenerational epigenetic effects in humans remains to be elucidated. In spite of the current limitations, available evidence supports the concept that epigenetics holds substantial potential for furthering our understanding of the molecular mechanisms of environmental toxicants, as well as for predicting health-related risks due to conditions of environmental exposure and individual susceptibility.
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ABSTRACT: Endocrine disruptors have recently been shown to promote an epigenetic transgenerational phenotype involving a number of disease states (e.g. male infertility). The anti-androgenic fungicide vinclozolin was found to act transiently at the time of embryonic sex determination to promote in the F1 generation a spermatogenic cell defect and subfertility in the male. When the animals were allowed to age up to 1 yr, a number of other disease states developed. This phenotype was transferred through the male germ line to all subsequent generations analyzed (F1-F4). The ability of an environmental factor (i.e. endocrine disruptor) to promote an epigenetic transgenerational phenotype impacts the potential hazards of environmental toxins, mechanisms of disease etiology, and evolutionary biology. The biological importance of the epigenetic actions of environmental agents is reviewed in the context of the primordial germ cell and development of epigenetic transgenerational phenotypes.Endocrinology 07/2006; 147(6 Suppl):S43-9. · 4.46 Impact Factor