Neddylation is critical to cortical development by regulating Wnt/β-catenin signaling

Wnt signaling plays a critical role in production and differentiation of neurons and undergoes a progressive reduction during cortical development. However, how Wnt signaling is regulated is not well understood. Here we provide evidence for an indispensable role of neddylation, a ubiquitylation-like protein modification, in inhibiting Wnt/beta-catenin signaling. We show that beta-catenin is neddylated; and inhibiting beta-catenin neddylation increases its nuclear accumulation and Wnt/beta-catenin signaling. To test this hypothesis in vivo, we mutated Nae1, an obligative subunit of the E1 for neddylation in cortical progenitors. The mutation leads to eventual reduction in radial glia progenitors (RGPs). Consequently, the production of intermediate progenitors (IPs) and neurons is reduced, and neuron migration is impaired, resulting in disorganization of the cerebral cortex. These phenotypes are similar to those of beta-catenin gain-of-function mice. Finally, suppressing beta-catenin expression is able to rescue deficits of Nae1 mutant mice. Together, these observations identified a mechanism to regulate Wnt/beta-catenin signaling in cortical development.