Fig. 3
From: Rejuvenation by cell reprogramming: a new horizon in gerontology
Diagrammatic representation of the cumulative DNA damage theory and the epigenetic model of aging. a Progressive age-related DNA damage that takes place in the genome of cells with age due to environmental insults. ROS, reactive oxygen species. b The upper diagram represents some of the progressive changes in histones H3 and H4 methylation and acetylation during normal aging. Changes in DNA methylation are represented by stemmed asterisks on DNA. The lower diagram represents the chronologic changes that may occur on the same epigenetic marks during OSKM gene-induced rejuvenation/dedifferentiation. Red symbols represent chromatin activating marks whereas black symbols correspond to chromatin-repressor marks. Blue wavy lines represent the gene transcripts