Ink4a/Arf Regulation by let-7b and Hmga2: A Genetic Pathway Governing Stem Cell Aging

Stem cell self-renewal capacity declines with age. In a recent issue of Cell, Nishino and colleagues (2008) show that Hmga2 maintains neural stem cell (NSC) function in young mice through repression of the Ink4a/Arf locus; in contrast, during aging, elevated let-7b blocks Hmga2 and contributes to declining NSC function.