Precise epigenetic modifications in stem cells control developmental programs and cell fate decisions. In particular, the addition or removal of trimethylation of histone 3 lysine 27 (H3K27me3) at lineage-specific genes has been linked to the repression of gene expression, and a precise balance of methyltransferases and demethylases within cells determines H3K27me3 levels. The demethylase UTX is essential for development and tissue homeostasis; however, a role for UTX in stem cell–mediated tissue regeneration is unknown. In this issue of the
Ling Liu, Thomas A. Rando
Activation and differentiation of satellite cells require precise temporal expression of linage-specific transcription factors.