E3 ubiquitin ligase RMND5A maintains the self-renewal state of human neural stem/precursor cells by regulating Wnt and mTOR signaling pathways.

During cortical development, neural stem/precursor cells (NS/PCs) sequentially produce neurons, astrocytes, and oligodendrocytes. Before producing these cells, human (h) NS/PCs undergo prolonged self-renewal to form a larger cortex than other mammals, although the mechanisms are mostly unknown. Here, we performed a gene knockout screen using the CRISPR/Cas9 system to search for genes involved in hNS/PC self-renewal. We identified RMND5A, encoding an E3 ubiquitin ligase, among the candidate genes. We further demonstrated that knockdown of RMND5A decreased proliferation and promoted neuronal differentiation of hNS/PCs through the activation and suppression of the Wnt and mTOR signaling pathways, respectively. Taken together, our findings suggest that RMND5A participates in the maintenance of hNS/PC self-renewal by modulating the Wnt and mTOR signaling pathways. Impact statement During cortical development, human neural stem/precursor cells (hNS/PCs) undergo prolonged self-renewal to form a larger cortex than other mammals, although the mechanisms are mostly unknown. We identified RMND5A, an E3 ubiquitin ligase, as essential for maintaining self-renewal of hNS/PCs, providing valuable insights into the evolutionary expansion of the human brain.