DNA methylation: a powerful epigenetic regulator

Throughout our lives, our DNA undergoes modifications linked to our diet, environment, diseases and adaptative phenomenons. They are called epigenetic modifications, and they are closely related to aging. Breakthroughs in quantitative methods for full genome analysis (genome-wide associated studies, or GWAS) allowed to shed some light on epigenetic modification and to study how they are regulated.

Epigenetic modifications are diverse and can happen at any time during a lifetime, as a reply to signals that our cells receive: stress, smoking, diet, hormonal response… They can be temporary and help the body face a specific emergency, or long-lasting, in which case they have a direct impact on gene expression and long-term DNA integrity. They can take many forms and result from the work of specific enzymes that add small structures to our DNA, either directly or through DNA-associated proteins like histones. The modifications we know best today are also the most common : glycosylation (sugar addition), methylation (addition of a methyl group on our DNA), and histone methylation and acetylation.

They have a direct impact on gene transcription (and full-protein generation) because they can block important DNA sites, as well as the access to sequences that are indispensable to transcription. Methylation can lead to the inactivation of a given gene. The alterations caused by aging-related methylation are called “epigenetic derivations”, a number of events that lead to the gradual de-methylation of the genome, and the hyper-methylation or certain areas called CpG islands [1].