"Epigenetic factors and environment"

Abstract

The term epigenetic means "above genetics" originally proposed by C. Waddington to describe the existence of heredity mechanisms. Epigenetic processes include mitotic and / or meiotic hereditary modifications to gene expression without altering the DNA sequence.In eukaryotes the epigenetic phenomena are related to the structure of chromatin and its configurations. DNA is organized into chromatin within the nucleus. Chromatin is a complex with DNA, histone proteins and no histone proteins, which have two functional states, heterochromatin and euchromatin. The nucleosome is the first level of chromatin organization that enables DNA packaging, regulating gene expression and making possible epigenetic phenomena. Chromatin allows different configurations of the same genome, causing various epigenomes and then different phenotypes.Histone modifications, DNA methylation and the activity of nonncRNA, are the major mechanism of epigenetic regulation in eukaryotes. Epigenome represents the connection between environment and genome. Environmental influences can affect the programming of the genome, activating specific pathways in cells that, through the mechanisms of epigenetic regulation, promote the stable remodeling of chromatin changing gene expression and phenotype. Some of these changes can be inherited to the progeny even when the environmental trigger is over. In humans, environmentally induced modification in the epigenome has also been linked to a variety of pathologies, nevertheless, DNA and chromatin alterations are reversible and the implementation of epigenetic therapies for the treatment of epigenetically based diseases is a field of ongoing research and shows amazing perspectives.

GALANI Maria