Defective DNA methylation/demethylation processes define aging-dependent methylation patterns

The process of aging culminates in a multitude of chronological irreversible changes at the cellular and molecular levels that push the organism toward a progressive loss of physiological integrity and increased susceptibility to disease. Mounting evidence indicates that aging trajectories can be closely tracked down by changes in the DNA methylation patterns over the entire lifespan. The tracing of underlying mechanisms is a promising research path to gain a deeper understanding of the molecular nature of aging. Here we discuss current knowledge about dynamics of DNA methylation in mammals and describe changes in DNA methylation occurring during aging. We explore mechanisms that could underpin aging-related DNA methylation changes and highlight models in which those changes can be understood in the context of the complex interplay between DNA methylation, chromatin states and their modulators.