Epigenetic maintenance of neural stem cell quiescence in the adult mouse hippocampus via Setd1a [RNA-Seq]

Quiescence, a hallmark of adult neural stem cells (NSCs), is required for maintaining the NSC pool to support life-long continuous neurogenesis in the adult dentate gyrus (DG). Whether epigenetic mechanisms can maintain NSC quiescence over long term in the adult brain is not well-understood. Here we showed that adult mice with haploinsufficiency of Setd1a, a schizophrenia risk gene encoding a histone H3K4 methyltransferase, exhibited substantially enlarged DG with increased number of dentate granule cells. Deletion of Setd1a specifically in quiescent NSCs in the adult DG promoted their activation and neurogenesis, which was countered by inhibition of histone demethylase LSD1. Mechanistically, RNA sequencing and CUT & RUN analyses of cultured quiescent adult NSCs revealed Setd1a deletion-induced transcriptional changes and Setd1a targets, among which down-regulation of Bhlhe40 promoted quiescent NSC activation in the adult DG. Together, our study revealed a Setd1a-dependent epigenetic mechanism that sustains NSC quiescence in the adult DG.