Scientists at the University of Georgia have identified a mechanism that determines the long life span of different animals. This was announced in a press release published on MedicalXpress.
The researchers found that a significant part of the aging process occurs due to epigenetic changes in the DNA regions formed by cytosine and guanine, which are linked to each other through phosphate bonds (CpG sites). Epigenetic changes in this case occur through methylation – the addition of a methyl group. This does not alter the DNA itself, but it does affect the activity of certain genes.
The methylation pattern changes with the age of animals, but aging is also influenced by another factor – double-stranded DNA strand breaks. These breaks are repaired by enzymes called chromatin modifiers. However, in this case, chromatin modifiers leave CpG islands (genomic regions with a large number of CpG sites), which leads to changes in gene expression and affects the fate of cells.
Longer species (humans, alligators, and elephants) have higher CpG levels. According to the scientists, this helps chromatin modifiers return to CpG islands after the breaks have been repaired, and also acts as a buffer to help keep most of the epigenetic control intact.
