title: Xenopus POU factors of subclass V inhibit activin/nodal signaling during gastrulation.
abstract: 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.
authors.affiliation: Department of Biochemistry, University of Ulm, Albert-Einstein-Allee 11, Ulm, Germany.
authors.forename: Ying
authors.initials: Y
authors.lastname: Cao
authors.forename: Doreen
authors.initials: D
authors.lastname: Siegel
authors.forename: Walter
authors.initials: W
authors.lastname: Knöchel
mesh_terms: D028341:Activins / Q000378:metabolism*; D000818:Animals; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D005775:Gastrula / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D009474:Neurons / Q000378:metabolism; D055457:Nodal Protein; D050809:POU Domain Factors / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D055457:Nodal Protein; C526008:Nodal protein, mouse; D050809:POU Domain Factors; D016212:Transforming Growth Factor beta; D028341:Activins; D012313:RNA