Cell cycle heterogeneity directs the timing of neural stem cell activation from quiescence

Abstract

Staging quiescent cells Tissue-specific stem cells either divide or wait in a quiescent state until needed by the body. Quiescent stem cells have been thought to reside in the G 0 stage before activating to reenter the cell cycle. However, Otsuki and Brand now show that most quiescent stem cells in the Drosophila brain are arrested in G 2 . Cells in the two phases display differences; for example, G 2 stem cells awaken more quickly than G 0 stem cells, with the conserved pseudokinase Tribbles playing a regulatory role. Elucidating the different pathways and mechanisms underlying quiescence could help to inform regenerative drug design. Science , this issue p. 99