title: POU-V factors antagonize maternal VegT activity and beta-Catenin signaling in Xenopus embryos.
abstract: VegT and beta-Catenin are key players in the hierarchy of factors that are required for induction and patterning of mesendoderm in Xenopus embryogenesis. By descending the genetic cascades, cells lose their pluripotent status and are determined to differentiate into distinct tissues. Mammalian Oct-3/4, a POU factor of subclass V (POU-V), is required for the maintenance of pluripotency of embryonic stem cells. However, its molecular function within the early embryo is yet poorly understood. We here show that the two maternal Xenopus POU-V factors, Oct-60 and Oct-25, inhibit transcription of genes activated by VegT and beta-Catenin. Maternal POU-V factors and maternal VegT show an opposite distribution along the animal/vegetal axis. Oct-25, VegT and Tcf3 interact with each other and form repression complexes on promoters of VegT and beta-Catenin target genes. We suggest that POU-V factors antagonize primary inducers to allow germ layer specification in a temporally and spatially coordinated manner.
authors.affiliation: Institute of Biochemistry, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
authors.forename: Ying
authors.initials: Y
authors.lastname: Cao
authors.forename: Doreen
authors.initials: D
authors.lastname: Siegel
authors.forename: Cornelia
authors.initials: C
authors.lastname: Donow
authors.forename: Sigrun
authors.initials: S
authors.lastname: Knöchel
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.forename: Walter
authors.initials: W
authors.lastname: Knöchel
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA; D024202:Electrophoretic Mobility Shift Assay; D008969:Molecular Sequence Data; D050809:POU Domain Factors / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014158:Transcription, Genetic; D014981:Xenopus; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051176:beta Catenin / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D050809:POU Domain Factors; D020825:T-Box Domain Proteins; C103966:VegT protein, Xenopus; D029867:Xenopus Proteins; D051176:beta Catenin; D004247:DNA