The nervous system of bilaterians arises from a small pool of neural progenitor cells (NPCs) that expresses SoxB genes, a family of transcription factors crucial for neurogenesis. The existence of NPCs has thus far been described in diverse species of Bilateria but not in its sister group, the Cnidaria. Hence, the evolutionary origin of NPCs remains obscure. Gemma Richards and Fabian Rentzsch (p. ) now investigate the cellular origin of neural cells in Nematostella vectensis, a sea anemone belonging to the Cnidaria group. They find that NvSoxB(2), a gene closely related to the bilaterian SoxB genes, is expressed in a mitotically active cell population that gives rise to three neuronal classes found in Nematostella. Further, using knockdown experiments, the authors showed that NvSoxB(2) is required for proper neural development. This study uncovers the existence of a dedicated NPC population for the first time outside bilaterians and identifies SoxB genes as ancient regulators of neurogenesis. Although many questions about the precise role of NvSoxB(2) in Nematostella remain to be answered, these results provide a fundamental insight into evolutionarily conserved core aspects of neural development.
