EGFR signaling determines the differentiation routes of neuroepithelial cells in the visual center of Drosophila.

The developing central nervous system is regionalized into different domains to generate functionally distinct brain structures. Although this regionalization is crucial for constructing a functional brain, its regulatory mechanisms remain unclear. Here, we investigated regulatory mechanisms of the regionalization of the fly visual center. The medulla and lamina, two different ganglia, originate from the same precursor. We found that loss of anterior open (Aop), a negative regulator of epidermal growth factor receptor (EGFR) signaling, resulted in the ectopic formation of medulla neural stem cells in the developing lamina. In contrast, the lamina was expanded and intruded into the medulla after misexpression of Aop. Our findings suggest that Aop inactivates EGFR signaling in the prospective lamina to escape differentiation into the medulla for successful regionalization.