title: The RNA-binding protein XSeb4R regulates maternal Sox3 at the posttranscriptional level during maternal-zygotic transition in Xenopus.
abstract: The maternal-zygotic transition (MZT) is an embryonic event that overlaps with and plays key roles in primary germ layer specification in vertebrates. During MZT, maternally supplied mRNAs are degraded while zygotic transcripts are synthesized to either reinforce the already specified cell fate or to trigger new cell identity. Here, we show that forced expression of the RNA-binding protein, XSeb4R, in animal pole blastomeres of Xenopus embryos, inappropriately stabilizes transcripts there, including maternal Sox3. This leads to the impaired ability of the ectodermal progenitors to respond to factors regulating brain patterning and their eventual loss by apoptosis. XSeb4R protein binds specifically to the 3'UTR of Sox3 mRNA. XSeb4R gain-of-function in ectodermal explants reveals increased stability of the maternal Sox3 transcripts, associated with a robust Sox3 protein production. Conversely, whereas XSeb4R depletion abolishes VegT expression, the amount of the maternal Sox3 mRNA is rather increased but without augmentation in the amount of Sox3 protein. Moreover, XSeb4R protein knockdown leads to the modification of the ectoderm-mesoderm boundary, marked by expanded/shifted expression of the mesodermal marker genes such as Xbra and Apod, followed by an expression inhibition of Epi. K., an ectodermal marker. Overall, our data suggest XSeb4R as a novel player in gene expression regulation, acting at the posttranscriptional level during ectoderm specification in Xenopus.
authors.affiliation: Laboratoire de Génétique du Développement, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires (IBMM), rue des Profs. Jeener et Brachet 12, B-6041 Gosselies, Belgium.
authors.forename: Souhila
authors.initials: S
authors.lastname: Bentaya
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Ghogomu
authors.forename: Jessica
authors.initials: J
authors.lastname: Vanhomwegen
authors.forename: Claude
authors.initials: C
authors.lastname: Van Campenhout
authors.forename: Aurore
authors.initials: A
authors.lastname: Thelie
authors.forename: Maxime
authors.initials: M
authors.lastname: Dhainaut
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Bellefroid
authors.forename: Jacob
authors.initials: J
authors.lastname: Souopgui
mesh_terms: D000818:Animals; D017209:Apoptosis; D001757:Blastomeres / Q000378:metabolism; D004475:Ectoderm / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008648:Mesoderm / Q000378:metabolism; D011485:Protein Binding; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000378:metabolism*; D055748:SOXB1 Transcription Factors / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D015053:Zygote / Q000254:growth & development*
chemical_list: D016601:RNA-Binding Proteins; C482980:SEB4R protein, Xenopus; D055748:SOXB1 Transcription Factors; C527788:Sox3 protein, Xenopus; D029867:Xenopus Proteins