Fezf2 promotes neuronal differentiation through localised activation of Wnt/β-catenin signalling during forebrain development

Brain regionalisation, neuronal subtype diversification and circuit connectivity are crucial events in the establishment of higher cognitive functions. Here we report the requirement for the transcriptional repressor Fezf2 for proper differentiation of neural progenitor cells during the development of the Xenopus forebrain. Depletion of Fezf2 induces apoptosis in postmitotic neural progenitors, with concomitant reduction in forebrain size and neuronal differentiation. Mechanistically, we found that Fezf2 stimulates neuronal differentiation by promoting Wnt/beta-catenin signalling in the developing forebrain. In addition, we show that Fezf2 promotes activation of Wnt/beta-catenin signalling by repressing the expression of two negative regulators of Wnt signalling, namely Ihx2 and Ihx9. Our findings suggest that Fezf2 plays an essential role in controlling when and where neuronal differentiation occurs within the developing forebrain and that it does so by promoting local Wnt/beta-catenin signalling via a double-repressor model.