Aging in humans refers to a multidimensional process of physical, psychological, and social change, though aging itself may not be a wonderful thing to most of us due to external signs such as greying hair and wrinkles.
Increasing number of studies have shown that Epigenetic regulatory mechanisms are increasingly appreciated as central to aging. In yeast studies, aging and consequent sterility are found to be correlated with a loss of characteristic heterochromatic silencing at telomeres, mating type locus, and rDNA repeats, which suggests that aging results at least in part from a failure to maintain proper chromatin structure with time. In culture senescent cells, Histone levels are also found to decline during replicative senescence, and several histone methylation and acetylation marks redistribute with senescence associated gene expression changes. Age-related chromatin changes have also been observed in mammalian model. For example, there are significant differences in DNA methylation patterns between young and old mice, and these methylation changes are consistent across a number of different tissue types. Studies on Age-related changes in nuclear structure indicate that aging process is also correlated with breakdown of nuclear architecture, which subsequently may affects regulation of gene expression.