title: SOXE neofunctionalization and elaboration of the neural crest during chordate evolution.
abstract: During chordate evolution, two genome-wide duplications facilitated acquisition of vertebrate traits, including emergence of neural crest cells (NCCs), in which neofunctionalization of the duplicated genes are thought to have facilitated development of craniofacial structures and the peripheral nervous system. How these duplicated genes evolve and acquire the ability to specify NC and their derivatives are largely unknown. Vertebrate SoxE paralogues, most notably Sox9/10, are essential for NC induction, delamination and lineage specification. In contrast, the basal chordate, amphioxus, has a single SoxE gene and lacks NC-like cells. Here, we test the hypothesis that duplication and divergence of an ancestral SoxE gene may have facilitated elaboration of NC lineages. By using an in vivo expression assay to compare effects of AmphiSoxE and vertebrate Sox9 on NC development, we demonstrate that all SOXE proteins possess similar DNA binding and homodimerization properties and can induce NCCs. However, AmphiSOXE is less efficient than SOX9 in transactivation activity and in the ability to preferentially promote glial over neuronal fate, a difference that lies within the combined properties of amino terminal and transactivation domains. We propose that acquisition of AmphiSoxE expression in the neural plate border led to NCC emergence while duplication and divergence produced advantageous mutations in vertebrate homologues, promoting elaboration of NC traits.
authors.affiliation: School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Andrew
authors.initials: A
authors.lastname: Tai
authors.affiliation: School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Martin
authors.initials: M
authors.lastname: Cheung
authors.affiliation: Genome Regulation Laboratory, Drug Discovery Pipeline, Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong, 510530, China.
authors.forename: Yong-Heng
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Genome Regulation Laboratory, Drug Discovery Pipeline, Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong, 510530, China.
authors.forename: Ralf
authors.initials: R
authors.lastname: Jauch
authors.affiliation: Division of Biology 139-74, California Institute of Technology, Pasadena, USA.
authors.forename: Marianne E
authors.initials: ME
authors.lastname: Bronner
authors.affiliation: School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Kathryn S E
authors.initials: KS
authors.lastname: Cheah
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002465:Cell Movement; D002642:Chick Embryo; D020440:Gene Duplication; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D064175:Lancelets / Q000235:genetics* / Q000502:physiology; D016013:Likelihood Functions; D008968:Molecular Conformation; D009432:Neural Crest / Q000166:cytology* / Q000502:physiology*; D054259:Neural Tube / Q000502:physiology; D009457:Neuroglia / Q000502:physiology; D009474:Neurons / Q000502:physiology; D010802:Phylogeny; D055503:Protein Multimerization; D055757:SOXE Transcription Factors / Q000235:genetics / Q000502:physiology*; D013045:Species Specificity; D015533:Transcriptional Activation; D014714:Vertebrates / Q000502:physiology
chemical_list: D055757:SOXE Transcription Factors