Epigenetic ageing

With age, cells tend to be hypomethylated globally, but show hypermethylation locally (e.g. at promoter CpG islands). This combination is also referred to as "epigenetic drift" and is a typical characteristic of epigenetic ageing.

Global hypomethylation:

• With increasing age, the total amount of DNA methylation in the genome decreases.
• Repetitive elements (LINEs, SINEs, satellite DNA) are particularly affected.
• Consequence: genomic instability, increased mutation rate.

Regional hypermethylation:

• At the same time, focal hypermethylation occurs at certain CpG islands in promoter regions.
• This often affects tumor suppressor genes and cell cycle regulation genes.
• Consequence: potentially reduced gene expression of important protective genes.