FOXO3 shares common targets with ASCL1 genome-wide and inhibits ASCL1-dependent neurogenesis

FOXO transcription factors are central regulators of longevity from worms to humans. FOXO3 – the FOXO isoform associated with exceptional human longevity – preserves adult neural stem cell pools. Here we identify FOXO3 direct targets genome-wide in primary cultures of adult neural progenitor cells (NPCs). Interestingly, FOXO3-bound sites are enriched for motifs for bHLH transcription factors and FOXO3 shares common targets with the pro-neuronal bHLH transcription factor ASCL1/MASH1 in NPCs. Analysis of the chromatin landscape reveals that FOXO3 and ASCL1 are particularly enriched at the enhancers of genes involved in neurogenic pathways. Intriguingly, FOXO3 inhibits ASCL1-dependent neurogenesis in NPCs and direct neuronal conversion in fibroblasts. FOXO3 also restrains neurogenesis in vivo. Our study identifies a genome-wide interaction between the pro-longevity transcription factor FOXO3 and the cell fate determinant ASCL1, and raises the possibility that FOXO3’s ability to restrain ASCL1-dependent neurogenesis may help preserve the neural stem cell pool.