Transgenic analysis of a SoxB gene reveals neural progenitor cells in the cnidarian Nematostella vectensis.
Bilaterian neurogenesis is characterized by the generation of diverse neural cell types from dedicated neural stem/progenitor cells (NPCs). However, the evolutionary origin of NPCs is unclear, as neurogenesis in representatives of the bilaterian sister group, the Cnidaria, occurs via interstitial stem cells that also possess broader, non-neural, developmental potential. We address this question by analysing neurogenesis in an anthozoan cnidarian, Nematostella vectensis. Using a transgenic reporter line, we show that NvSoxB(2) - an orthologue of bilaterian SoxB genes that have conserved roles in neurogenesis - is expressed in a cell population that gives rise to sensory neurons, ganglion neurons and nematocytes: the three primary neural cell types of cnidarians. EdU labelling together with in situ hybridization, and within the NvSoxB(2)::mOrange transgenic line, demonstrates that cells express NvSoxB(2) before mitosis and identifies asymmetric behaviours of sibling cells within NvSoxB(2)(+) lineages. Morpholino-mediated gene knockdown of NvSoxB(2) blocks the formation of all three neural cell types, thereby identifying NvSoxB(2) as an essential positive regulator of nervous system development. Our results demonstrate that diverse neural cell types derive from an NvSoxB(2)-expressing population of mitotic cells in Nematostella and that SoxB genes are ancient components of a neurogenic program. To our knowledge this is the first description of a lineage-restricted, multipotent cell population outside the Bilateria and we propose that neurogenesis via dedicated, SoxB-expressing NPCs predates the split between cnidarians and bilaterians.
Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, Bergen N-5008, Norway.
Gemma Sian
GS
Richards
Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, Bergen N-5008, Norway fabian.rentzsch@sars.uib.no.
Fabian
F
Rentzsch
D000818:Animals; D005075:Biological Evolution; D019070:Cell Lineage / Q000502:physiology; D005724:Ganglia / Q000166:cytology / Q000378:metabolism; D055785:Gene Knockdown Techniques; D018014:Gene Transfer Techniques; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D060172:Morpholinos / Q000235:genetics; D039902:Multipotent Stem Cells / Q000502:physiology*; D058894:Nematocyst / Q000166:cytology / Q000378:metabolism; D058953:Neural Stem Cells / Q000378:metabolism*; D055495:Neurogenesis / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055749:SOXB2 Transcription Factors / Q000235:genetics* / Q000378:metabolism; D012615:Sea Anemones / Q000166:cytology* / Q000235:genetics*; D011984:Sensory Receptor Cells / Q000378:metabolism
D060172:Morpholinos; D055749:SOXB2 Transcription Factors
Cnidaria; Nematostella; Neural progenitor cells; Neurogenesis; SoxB genes