Investigating the Roles of Cellular Senescence in Embryogenesis and Aging

The study explored the dual role of cellular senescence in aging and embryonic development. In aging, it was found that Keratin-15 positive hair follicle stem cells increased with age but had reduced functionality and stress tolerance, potentially due to extrinsic senescence affecting epidermal Jak-Stat signaling. This suggested that epidermal stem cell decline contributed to tissue aging. In embryogenesis, senescence was identified as a normal mechanism, particularly in the apical ectodermal ridge and hindbrain neural tube, dependent on p21. Mice lacking p21 showed defects in embryonic senescence and limb patterning. The study also noted gene-expression similarities between developmental and oncogene-induced senescence, indicating a shared function. Senescence was suggested to have evolved as a developmental mechanism, later adapted for adult roles.