title: Neurogenic gene regulatory pathways in the sea urchin embryo.
abstract: During embryogenesis the sea urchin early pluteus larva differentiates 40-50 neurons marked by expression of the pan-neural marker synaptotagmin B (SynB) that are distributed along the ciliary band, in the apical plate and pharyngeal endoderm, and 4-6 serotonergic neurons that are confined to the apical plate. Development of all neurons has been shown to depend on the function of Six3. Using a combination of molecular screens and tests of gene function by morpholino-mediated knockdown, we identified SoxC and Brn1/2/4, which function sequentially in the neurogenic regulatory pathway and are also required for the differentiation of all neurons. Misexpression of Brn1/2/4 at low dose caused an increase in the number of serotonin-expressing cells and at higher dose converted most of the embryo to a neurogenic epithelial sphere expressing the Hnf6 ciliary band marker. A third factor, Z167, was shown to work downstream of the Six3 and SoxC core factors and to define a branch specific for the differentiation of serotonergic neurons. These results provide a framework for building a gene regulatory network for neurogenesis in the sea urchin embryo.
authors.affiliation: National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wei
authors.affiliation: National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Angerer
authors.affiliation: National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA rang@mail.nih.gov.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Angerer
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D050809:POU Domain Factors / Q000235:genetics / Q000378:metabolism; D012617:Sea Urchins / Q000196:embryology* / Q000378:metabolism*; D000097607:Homeobox Protein SIX3
chemical_list: D005136:Eye Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D050809:POU Domain Factors; D000097607:Homeobox Protein SIX3; C085076:transcription factor Brn-2; C074065:Pou3f3 protein, mouse
keywords: Brn1/2/4; Embryogenesis; Neurogenesis; Sea urchin; Six3; SoxC; Strongylocentrotus purpuratus