The secret lives of stem cells: unraveling the molecular basis of stem cell aging.

摘要

Although DNA demethylation is required to maintain stem cell properties, it has been reported that the role of DNMTs are distinct between embryonic stem cells (ESCs) and adult stem cells. Our recent findings agree that the levels of DNMT1 and DNMT3b decrease, while human umbilical cord blood stem cells (hUCB-SCs) lose their self-renewal and multipotency. However, 5-azacytidine (5-AZA), an inhibitor of DNMT analogous to cystidine, rapidly induced cellular senescence of hUCB-SCs through activation of p16~(INK4A) and p21~(CIP1)/WAF1. The epigenetic characteristics of adult stem cells, as opposed to ESCs, are likely to be more susceptible to DNMTs due to the presence of differential mechanisms. Moreover, DNMTs could lead to a delay of the aging process of adult stem cells.