1. Small C-terminal Domain Phosphatase 3 Dephosphorylates the Linker Sites of Receptor-regulated Smads (R-Smads) to Ensure Transforming Growth Factor β (TGFβ)-mediated Germ Layer Induction in Xenopus Embryos.
- Author
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Sun G, Hu Z, Min Z, Yan X, Guan Z, Su H, Fu Y, Ma X, Chen YG, Zhang MQ, Tao Q, and Wu W
- Subjects
- Activins metabolism, Animals, Binding Sites, Blastula embryology, Blastula metabolism, Bone Morphogenetic Proteins metabolism, Female, Gastrula embryology, Gastrula metabolism, Gene Knockdown Techniques, Germ Layers embryology, Germ Layers metabolism, Ligands, Nodal Signaling Ligands metabolism, Phosphoprotein Phosphatases antagonists & inhibitors, Phosphoprotein Phosphatases genetics, Phosphorylation, RNA, Messenger genetics, RNA, Messenger metabolism, RNA, Small Interfering genetics, Signal Transduction, Smad Proteins, Receptor-Regulated chemistry, Xenopus Proteins antagonists & inhibitors, Xenopus Proteins genetics, Xenopus laevis genetics, Phosphoprotein Phosphatases metabolism, Smad Proteins, Receptor-Regulated metabolism, Transforming Growth Factor beta metabolism, Xenopus Proteins metabolism, Xenopus laevis embryology, Xenopus laevis metabolism
- Abstract
Germ layer induction is one of the earliest events shortly after fertilization that initiates body formation of vertebrate embryos. In Xenopus, the maternally deposited transcriptional factor VegT promotes the expression of zygotic Nodal/Activin ligands that further form a morphogen gradient along the vegetal-animal axis and trigger the induction of the three germ layers. Here we found that SCP3 (small C-terminal domain phosphatase 3) is maternally expressed and vegetally enriched in Xenopus embryos and is essential for the timely induction of germ layers. SCP3 is required for the full activation of Nodal/Activin and bone morphogenetic protein signals and functions via dephosphorylation in the linker regions of receptor-regulated Smads. Consistently, the linker regions of receptor-regulated Smads are heavily phosphorylated in fertilized eggs, and this phosphorylation is gradually removed when embryos approach the midblastula transition. Knockdown of maternal SCP3 attenuates these dephosphorylation events and the activation of Nodal/Activin and bone morphogenetic protein signals after midblastula transition. This study thus suggested that the maternal SCP3 serves as a vegetally enriched, intrinsic factor to ensure a prepared status of Smads for their activation by the upcoming ligands during germ layer induction of Xenopus embryos., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
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