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Biol Open 2021 Feb 25;102:. doi: 10.1242/bio.051797.
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Segregation of brain and organizer precursors is differentially regulated by Nodal signaling at blastula stage.

Castro Colabianchi AM , Tavella MB , Boyadjián López LE , Rubinstein M , Franchini LF , López SL .

The blastula Chordin- and Noggin-expressing (BCNE) center comprises animal-dorsal and marginal-dorsal cells of the amphibian blastula and contains the precursors of the brain and the gastrula organizer. Previous findings suggested that the BCNE behaves as a homogeneous cell population that only depends on nuclear β-catenin activity but does not require Nodal and later segregates into its descendants during gastrulation. In contrast to previous findings, in this work, we show that the BCNE does not behave as a homogeneous cell population in response to Nodal antagonists. In fact, we found that chordin.1 expression in a marginal subpopulation of notochordal precursors indeed requires Nodal input. We also establish that an animal BCNE subpopulation of cells that express both, chordin.1 and sox2 (a marker of pluripotent neuroectodermal cells), and gives rise to most of the brain, persisted at blastula stage after blocking Nodal. Therefore, Nodal signaling is required to define a population of chordin.1+ cells and to restrict the recruitment of brain precursors within the BCNE as early as at blastula stage. We discuss our findings in Xenopus in comparison to other vertebrate models, uncovering similitudes in early brain induction and delimitation through Nodal signaling.

PubMed ID: 33563608
PMC ID: PMC7928228
Article link: Biol Open

Species referenced: Xenopus laevis
Genes referenced: cer1 chrd chrd.2 chrdl1 ctnnb1 foxh1 gsc hes4 hesx1 mcf2 mix1 myod1 nodal nodal1 nodal2 nog psmd6 sia1 smad2 smad4 sox2 tbxt vegt
GO keywords: gastrulation [+]

Article Images: [+] show captions
References [+] :
Agius, Endodermal Nodal-related signals and mesoderm induction in Xenopus. 2000, Pubmed, Xenbase