The developmental aging and origins of health and disease hypotheses explained by different protein networks.

One theory that attempts to explain how and why an organism ages is the developmental hypothesis of aging (DevAge), which describes how developmental programming leads to aging in adults. Interestingly, the developmental origins of health and disease hypothesis (DOHaD) asserts that some aging-associated diseases that occur in adults are closely related to development and to conditions in the intrauterine environment. Thus, both aging and aging-associated diseases can be viewed, at least in part, as the result of a developmental program that is activated early in embryogenesis and persists throughout the lifespan of the organism. We would expect this developmental program to be regulated by a set of interacting protein networks that connect environmental and molecular signals. However, the connection between aging and development is not clear. Thus, a systems biology approach that incorporates different "omic" databases for two mammalian models, Homo sapiens and Mus musculus, was used to evaluate how development and aging are interconnected. Interestingly, three major, evolutionarily conserved processes, namely the immune system, epigenetics, and aerobic metabolism, appear to regulate aging and development in both H. sapiens and M. musculus. Considering that these three processes are essential to embryogenesis, the protein networks within these processes are subjected to strong selective pressure to eliminate gross developmental abnormalities in early embryogenesis. This selective pressure becomes more relaxed in the adult organism, permitting the onset of aging-associated diseases and inflammation-related aging; this concept echoes the antagonistic pleiotropy hypothesis of aging.