Article
- The EMBO Journal (2007) 26, 2942 - 2954
- doi:10.1038/sj.emboj.7601736
Published online: 31 May 2007
Subject Category:
POU-V factors antagonize maternal VegT activity and 
-Catenin signaling in Xenopus embryos
Ying Cao1, Doreen Siegel1, Cornelia Donow1, Sigrun Knöchel1, Li Yuan1 and Walter Knöchel1
- Institute of Biochemistry, University of Ulm, Ulm, Germany
Correspondence to:
Walter Knöchel, Institut für Biochemie, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany. Tel.: 0049 731/502 3280; Fax: 0049 731/502 3277; E-mail: walter.knoechel@uni-ulm.de
Received 1 December 2006; Accepted 7 May 2007
Abstract
VegT and 
-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 -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 -Catenin target genes. We suggest that POU-V factors antagonize primary inducers to allow germ layer specification in a temporally and spatially coordinated manner.
Keywords:
- -Catenin,
- germ layers,
- POU-V factors,
- VegT,
- Xenopus laevis
