Epigenetics Recording Varied Environment and Complex Cell Events is an Origin of Cellular Aging

Although the phenomenal relationship between epigenetics and aging phenotypic changes is built up, an intrinsic connection between the epigenetics and aging requires to be theoretically illuminated. In this study, we propose epigenetic recording of varied cell environment and complex history could be an origin of cellular aging. Through epigenetic modifications, the environment and historical events can induce the chromatin template into activated or repressive accessible structure, thereby shaping the DNA template into a spectrum of chromatin states. The inner nature of diversity and conflicts born by cell environment and its historical events are hence recorded into the chromatin template. This could result in a dissipated spectrum of chromatin state and chaos of overall gene expressions. An unavoidable degradation of epigenome entropy, similar to Shannon entropy, would be consequently induced. The resulted disorder in epigenome, characterized by corrosion of epigenome entropy as reflected in chromatin template, can be stably memorized and propagated through cell divisions. Furthermore, hysteresis nature of epigenetics responding to emerging environment could exacerbate the degradation of epigenome entropy. Besides stochastic errors, we propose that epigenetics disorder and chaos derived from unordered environment and complex cell experiences play an essential role in epigenetic drift and the as-resulted cellular aging.