title: Activin ligands are required for the re-activation of Smad2 signalling after neurulation and vascular development in Xenopus tropicalis.
abstract: The importance of Transforming Growth Factor β (TGFβ) signalling during early development has been well established. In particular, Nodal ligands have been shown to play essential roles for the specification and the patterning of the mesendoderm, axes formation and organogenesis. Activin ligands, like Nodal, signal by inducing the phosphorylation of the intracellular signal transducers Smad2 and Smad3. However, the roles of Activins during embryonic development are much less understood. Here, we report that during Xenopus tropicalis development two waves of Smad2 phoshorylation can be observed, first during gastrulation and then a second one after neurulation. Using a knock-down approach, we show that the second wave of Smad2 phosphorylation depends on activinβa (actβa) and activinβb (actβb) expression. Knocking down the expression of actβa, or treating the embryos with a chemical inhibitor inhibiting TGFβ receptor I (TGFβRI) activity after neurulation result in a decrease of the expression of endothelial cell markers and a lack of blood flow in Xenopus tadpoles. Taken together these data suggest that Activin ligands play an important role during vascular development in Xenopus tropicalis embryos.
authors.affiliation: The Healing Foundation Centre, Faculty of Life Sciences, University of Manchester, UK.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nagamori
authors.forename: Samantha
authors.initials: S
authors.lastname: Roberts
authors.forename: Marissa
authors.initials: M
authors.lastname: Maciej
authors.forename: Karel
authors.initials: K
authors.lastname: Dorey
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology; D002196:Capillaries / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D047108:Embryonic Development / Q000502:physiology; D004789:Enzyme Activation; D054262:Gastrulation / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D028322:Inhibin-beta Subunits / Q000235:genetics / Q000378:metabolism*; D060172:Morpholinos / Q000235:genetics; D054261:Neurulation / Q000502:physiology*; D055457:Nodal Protein / Q000378:metabolism; D038081:Organogenesis / Q000502:physiology; D010766:Phosphorylation; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism*; D051900:Smad3 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta; D014981:Xenopus; D029867:Xenopus Proteins / Q000378:metabolism*
chemical_list: D060172:Morpholinos; D055457:Nodal Protein; D018125:Receptors, Transforming Growth Factor beta; D051899:Smad2 Protein; C497785:Smad2 protein, Xenopus; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C103008:inhibin beta A subunit; D028322:Inhibin-beta Subunits