The Epigenetic Regulation of Telomere Maintenance in Aging

Aging is a complex process influenced by a combination of genetic, epigenetic, and environmental factors. Genetic components donate almost 30% of the aging phenotypic variance, while epigenetic modifications that serve as environment X gene mediator are considered to be the major contributors. Epigenetic modifications (i.e., DNA methylation and histone modifications) can affect the gene expression and genomic stability and thus underlie age-associated diseases. Another mechanism found to be involved (may serve as a biomarker) with aging process is telomere attrition. Cellular telomeres shorten with age until a critical length, which results in a vital genomic material loss, thus triggering the cell to enter replicative senescence. This attrition is compensated by telomerase activity that maintains telomere length and support cell proliferation. Telomere length and telomerase activity are also regulated by epigenetic modifications that shape the telomere structure and influence its maintenance. Furthermore, telomeres can regulate epigenetic factors affecting gene expression of nearby genes. In sum, there is a clear cross talk between telomeres maintenance and epigenetic modifications that accompanied aging and age-related pathologies.