Stem cells residing in the outer layer of the skin are extremely resistant to cell death following DNA damage, reports a study published in Nature Cell Biology this week. Little is known about how stem cells sense and respond to DNA damage to ensure the transmission of accurate genetic information, so these findings may have important implications for understanding the increased susceptibility of certain tissues to DNA damage-induced tumour development and ageing.
Stem cells are at high risk of accumulating deleterious mutations since they reside and self-renew in the adult tissues for extended periods of time. The balance between the maintenance of genomic integrity and the preservation of tissue integrity following DNA damage is therefore crucial to ensure tissue turnover while avoiding cancer and ageing. Cedric Blanpain and colleagues find that, following DNA damage, hair follicle stem cells are protected from cell death - known as apoptosis. This is due to the increased expression of the anti-apoptotic protein Bcl-2 and to accelerated DNA repair, which is mediated by the non-homologous end joining (NHEJ) DNA repair pathway that repairs double strand damage to DNA.