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Mech Dev August 1, 2006; 123 (8): 614-25.

Xenopus POU factors of subclass V inhibit activin/nodal signaling during gastrulation.

Three POU factors of subclass V, Oct-25, Oct-60 and Oct-91 are expressed in Xenopus oocytes and early embryos. We here demonstrate that vegetal overexpression of Oct-25, Oct-60, Oct-91 or mammalian Oct-3/4 suppresses mesendoderm formation in Xenopus embryos. Oct-25 and Oct-60 are shown to inhibit activin/nodal and FGF signaling pathways. Loss of Oct-25 and Oct-60 function results in elevated transcription of mesendodermal marker genes and ectopic formation of endoderm in the equatorial region of gastrula stage embryos. Within the ectoderm, Oct-25 promotes neural fate by upregulating neuroectodermal genes, such as Xsox2, which prevent differentiation of neural progenitors into neurons. We also show that mouse Oct-3/4 and Xenopus Oct-25 or Oct-60 behave as functional homologues. We conclude that Xenopus Oct proteins are required to control the levels of embryonic signaling pathways, thereby ensuring the correct specification of germ layers.

PubMed ID: 16860542
Article link: Mech Dev

Species referenced: Xenopus laevis
Genes referenced: myc nodal nodal1 pou5f3.1 pou5f3.2 pou5f3.3 sox17a sox2 tbxt
Morpholinos: pou5f3.2 MO2 pou5f3.3 MO1 pou5f3.3 MO5

Phenotypes: Xla Wt + Mmu.Pou5f1 (fig.1.e) [+]

Article Images: [+] show captions