Histone modification

Histone modifications are reversible chemical changes to histone proteins around which DNA is wound, including acetylation, methylation, phosphorylation, and ubiquitination. They reshape chromatin structure and recruit regulatory complexes, thereby controlling gene transcription, DNA repair, and replication. The combined pattern is often called the histone code. Age-related shifts in histone marks contribute to epigenetic drift, loss of cellular identity, and dysregulated stress and longevity pathways.