NOTCH, ERK and SHH signaling respectively control the fate determination of cortical astrocytes, oligodendrocytes, and olfactory bulb interneurons [CUT&Tag]

During cortical development, radial glial cells, known as neural stem cells, initially generate a large number of cortical glutamatergic pyramidal neurons through a process called neurogenesis. This is followed by the generation of a diversity of cortical astrocytes, oligodendrocytes, and olfactory bulb interneurons, known as gliogenesis. However, the molecular mechanisms underlying the switch from cortical neurogenesis to gliogenesis, and the subsequent fate determination of cortical astrocytes, oligodendrocytes, and olfactory bulb interneurons, remain unclear. Here, we report that extracellular signal-regulated kinase (ERK) signaling plays a fundamental role in promoting cortical gliogenesis and the generation of cortical glial progenitors. Additionally, SHH-SMO-GLI activator signaling has an auxiliary function to ERK during these processes. We further demonstrate that NOTCH signaling is absolutely required for the fate determination of astrocytes, while ERK signaling plays a prominent role in oligodendrocyte fate specification, and SHH signaling is crucial for the fate determination of olfactory bulb interneurons from cortical progenitors. We provide evidence suggesting that this mechanism is conserved in both mice and humans. Finally, we propose a unifying principle of mammalian cortical gliogenesis.