While epigenetic modifications are critical for cell state changes throughout development, a detailed characterization of chromatin accessibility during neurogenesis has not been explored. We collected single-cell chromatin accessibility profiles from four distinct neurogenic regions of the embryonic mouse forebrain using single nuclei ATAC-Seq (snATAC-Seq). We identified thousands of differentially accessible peaks, many restricted to distinct progenitor cell types or brain regions. Integrating snATAC-Seq and transcriptome data, we characterized changes of chromatin accessibility at enhancers and promoters that were tightly coupled to transcript abundance during neurodevelopment. Integrating chromatin accessibility profiles from embryonic and adult interneurons with the iPSYCH2012 dataset revealed several disease-associated polymorphisms overlapped with accessible regions in embryonic cells. These findings highlight a diverse chromatin landscape in embryonic neural progenitors, extensive coordination between chromatin accessibility and gene expression during neuron fate determination, and open the door for future studies to define critical enhancer-promoter interactions that direct cell fate decisions.

The ventricular zone (VZ) of the nervous system contains radial glia cells that were originally considered relatively homogenous in their gene expression. However, a detailed characterization of transcriptional diversity in these VZ cells has not been reported. Here, we performed single-cell RNA sequencing to characterize transcriptional heterogeneity of neural progenitors within the VZ and subventricular zone (SVZ) of the mouse embryonic cortex and ganglionic eminences (GEs). By using a transgenic mouse line to enrich for VZ cells, we detect significant transcriptional heterogeneity within VZ and SVZ progenitors, both between forebrain regions and within spatial subdomains of specific GEs. Additionally, we observe differential gene expression between E12.5 and E14.5 VZ cells, which could provide insights into temporal changes in cell fate. Together, our results reveal a previously unknown spatial and temporal genetic diversity of telencephalic VZ cells that will aid our understanding of initial fate decisions in the forebrain.