RESUMO
The high-mobility-group domain containing SoxC transcription factors Sox4 and Sox11 are expressed and required in the vertebrate central nervous system in neuronal precursors and neuroblasts. To identify genes that are widely regulated by SoxC proteins during vertebrate neurogenesis we generated expression profiles from developing mouse brain and chicken neural tube with reduced SoxC expression and found the transcription factor prospero homeobox protein 1 (Prox1) strongly down-regulated under both conditions. This led us to hypothesize that Prox1 expression depends on SoxC proteins in the developing central nervous system of mouse and chicken. By combining luciferase reporter assays and over-expression in the chicken neural tube with in vivo and in vitro binding studies, we identify the Prox1 gene promoter and two upstream enhancers at -44 kb and -40 kb relative to the transcription start as regulatory regions that are bound and activated by SoxC proteins. This argues that Prox1 is a direct target gene of SoxC proteins during neurogenesis. Electroporations in the chicken neural tube furthermore show that Prox1 activates a subset of SoxC target genes, whereas it has no effects on others. We propose that the transcriptional control of Prox1 by SoxC proteins may ensure coupling of two types of transcription factors that are both required during early neurogenesis, but have at least in part distinct functions. Open Data: Materials are available on https://cos.io/our-services/open-science-badges/ https://osf.io/93n6m/.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Proteínas de Homeodomínio/metabolismo , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Prosencéfalo/citologia , Fatores de Transcrição SOXC/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Embrião de Galinha , Imunoprecipitação da Cromatina , Biologia Computacional , Ensaio de Desvio de Mobilidade Eletroforética , Eletroporação , Embrião de Mamíferos , Ontologia Genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Homeodomínio/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Tubo Neural/citologia , Tubo Neural/metabolismo , Fatores do Domínio POU/genética , Fatores do Domínio POU/metabolismo , Prosencéfalo/embriologia , Prosencéfalo/crescimento & desenvolvimento , Prosencéfalo/metabolismo , Fatores de Transcrição SOXC/genética , Tubulina (Proteína)/metabolismo , Proteínas Supressoras de Tumor/genéticaRESUMO
Development of the mouse CNS was reported to be normal in the absence of either Sox4 or its close relative Sox11 despite strong and widespread expression of both transcription factors. In this study, we show that combined absence of both Sox proteins in the mouse leads to severe hypoplasia of the developing spinal cord. Proliferation of neuroepithelial precursor cells in the ventricular zone was unaffected. These cells also acquired their correct positional identity. Both glial and neuronal progenitors were generated and neurons appeared in a similar spatiotemporal pattern as in the wild-type. Rates of cell death were however dramatically increased throughout embryogenesis in the double deficient spinal cord arguing that Sox4 and Sox11 are jointly and redundantly required for cell survival. The absence of pronounced proliferation, patterning, specification, and maturation defects furthermore indicates that the decreased cell survival is not a secondary effect of one of these events. We therefore conclude that the two Sox proteins directly function as pro-survival factors during spinal cord development in neural cell types.
