Pax6 targets in neural stem cells. Mus musculus

Pax6 is a highly conserved transcription factor among vertebrates and is important in various aspects of the central nervous system (CNS) development. However, the gene regulatory circuitry of Pax6 underlying these functions remains elusive. We find that, following expression in neural progenitor cells, Pax6 targets many promoters embedded in an active chromatin environment. Intriguingly, many of these sites are also bound by another progenitor factor, Sox2, which cooperates with Pax6 in gene regulation. A combinatorial analysis of Pax6 binding dataset with transcriptome changes in Pax6-deficient neural progenitors reveals a dual role for Pax6, in which it activates the neuronal (ectodermal) genes while concurrently represses the mesodermal and endodermal genes thereby ensuring the unidirectionality of lineage commitment towards glutamatergic neuronal differentiation. Furthermore, Pax6 is critical for inducing activity of transcription factors that elicit neurogenesis and repress others that promote non-neuronal lineages. In addition to many established downstream effectors, Pax6 directly binds and activates a number of genes that are specifically expressed in neural progenitors but have not been previously implicated in neurogenesis. The in utero knockdown of one such gene, Ift74, during brain development impairs polarity and migration of new-born neurons. These findings demonstrate new aspects of the gene regulatory circuitry of Pax6, revealing how it functions to control neuronal development at multiple levels to ensure unidirectionality and proper execution of the neurogenic program. Overall design: Pax6 chip-chip was performed in neural stem cells to elucidate its genomic targets and down-stream gene regulatory network