R-loop landscapes in the developing human brain are linked to neural differentiation and cell type-specific...

Here, we construct genome-scale maps of R-loops, three-stranded nucleic acid structures comprised of a DNA/RNA hybrid and a displaced single strand of DNA, in both proliferative and differentiated zones of the human prenatal brain. We show that R-loops are abundant in the progenitor-rich germinal matrix and preferentially form at gene promoters slated for upregulated expression at later stages of differentiation, including numerous neurodevelopmental risk genes. RNase H1-mediated contraction of the genomic R-loop space in neural progenitors shifted differentiation toward the neuronal lineage and was associated with transcriptomic alterations, along with defective functional and structural neuronal connectivity in vivo and in vitro. Therefore, we conclude that R-loops are important for fine-tuning differentiation-sensitive gene expression programs of neural progenitor cells.