title: Xebf3 is a regulator of neuronal differentiation during primary neurogenesis in Xenopus.
abstract: During primary neurogenesis in Xenopus, a cascade of helix--loop--helix (HLH) transcription factors regulates neuronal determination and differentiation. While XNeuroD functions at a late step in this cascade to regulate neuronal differentiation, the factors that carry out terminal differentiation are still unknown. We have isolated a new Xenopus member of the Ebf/Olf-1 family of HLH transcription factors, Xebf3, and provide evidence that, during primary neurogenesis, it regulates neuronal differentiation downstream of XNeuroD. In developing Xenopus embryos, Xebf3 is turned on in the three stripes of primary neurons at stage 15.5, after XNeuroD. In vitro, XEBF3 binds the EBF/OLF-1 binding site and functions as a transcriptional activator. When overexpressed, Xebf3 is able to induce ectopic neurons at neural plate stages and directly convert ectodermal cells into neurons in animal cap explants. Expression of Xebf3 can be activated by XNeuroD both in whole embryos and in animal caps, indicating that this new HLH factor might be regulated by XNeuroD. Furthermore, in animal caps, XNeuroD can activate Xebf3 in the absence of protein synthesis, suggesting that, in vitro, this regulation is direct. Similar to XNeuroD, but unlike Xebf2/Xcoe2, Xebf3 expression and function are insensitive to Delta/Notch-mediated lateral inhibition. In summary, we conclude that Xebf3 functions downstream of XNeuroD and is a regulator of neuronal differentiation in Xenopus.
authors.affiliation: Department of Neuroscience, San Raffaele Scientific Institute (HSR), Milan, Italy.
authors.forename: O
authors.initials: O
authors.lastname: Pozzoli
authors.forename: A
authors.initials: A
authors.lastname: Bosetti
authors.forename: L
authors.initials: L
authors.lastname: Croci
authors.forename: G G
authors.initials: GG
authors.lastname: Consalez
authors.forename: M L
authors.initials: ML
authors.lastname: Vetter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D009420:Nervous System / Q000166:cytology / Q000196:embryology*; D009474:Neurons / Q000166:cytology; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C484669:EBF3 protein, Xenopus; C489922:Ebf2 protein, mouse; C093564:Neurogenic differentiation factor 1