Differential Expression Levels of Sox9 in Early Neocortical Radial Glial Cells Regulate the Decision Between Stem Cell Maintenance and Differentiation

The study, conducted three years ago, investigated the heterogeneity of radial glial progenitor cells (RGCs) in the dorsal forebrain, which are known to produce excitatory projection neurons and macroglia of the neocortex. Using single cell RNA sequencing, the researchers identified two subtypes of RGCs with different neurogenic behaviors. One subtype rapidly produced postmitotic neurons, while the other remained relatively quiescent before generating neurons. The study found that the transcription factor Sox9 was differentially expressed between these RGC subtypes. Elevated Sox9 expression in progenitors prevented RGC division and led to the generation of upper-layer cortical neurons from these progenitors at later ages. This indicated that Sox9 played a critical role in maintaining RGCs and regulating the generation of upper layer neurons.