Activin ligands are required for the re-activation of Smad2 signalling after neurulation and vascular development in Xenopus tropicalis

作者：Nagamori Yuki; Roberts Samantha; Maciej Marissa; Dorey Karel^*

来源：International Journal of Developmental Biology, 2014, 58(10-12): 783-791.

DOI：10.1387/ijdb.140244kd

• Activin
• vasculogenesis
• TGF beta
• Xenopus
• Smad

The importance of Transforming Growth Factor beta (TGF beta) 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 activin beta a (act beta a) and activin beta b (act beta b) expression. Knocking down the expression of act beta a, or treating the embryos with a chemical inhibitor inhibiting TGF beta receptor I (TGF beta RI) activity after neurulation result in a decrease of the expression of endothelial cell markers and a lack of blood flow in Xenopustadpoles. Taken together these data suggest that Activin ligands play an important role during vascular development in Xenopus tropicalis embryos.

• 出版日期2014