Cellular senescence in development, regeneration and disease.

Cellular senescence is a state comprising an essentially irreversible proliferative arrest combined with phenotypic changes and pronounced secretory activity. Although senescence has long been linked with aging, recent studies have uncovered functional roles for senescence in embryonic development, regeneration and reprogramming, and have helped to advance our understanding of this process as a highly coordinated and programmed cellular state. In this Primer article, we summarize some of the key findings in the field and attempt to explain them in a simple model that reconciles the normal and pathological roles for senescence.

The senescence-associated secretory phenotype induces cellular plasticity and tissue regeneration.

Senescence is a form of cell cycle arrest induced by stress such as DNA damage and oncogenes. However, while arrested, senescent cells secrete a variety of proteins collectively known as the senescence-associated secretory phenotype (SASP), which can reinforce the arrest and induce senescence in a paracrine manner. However, the SASP has also been shown to favor embryonic development, wound healing, and even tumor growth, suggesting more complex physiological roles than currently understood.