Written in development and lost in ageing: the grammar of cellular identity.

Ageing results from the progressive loss of cellular identity constraints, with 90% of age-related DNA methylation changes occurring at PRC2-bound regions in mammals.

• Why it matters: Understanding the mechanistic basis of ageing is crucial because current theories lack clarity on how cellular identity deteriorates over time, impacting health and lifespan.
• What they did: The study analyzed chromatin programs and DNA methylation patterns across tissues, focusing on the antagonistic roles of PRC2 and H3K4/36 methylation, revealing age-related drift in identity boundaries.
• The result: Findings suggest that stabilizing chromatin architecture could preserve cellular identity, offering avenues for interventions to slow or reverse aspects of biological ageing.