The POU factor Oct-25 regulates the Xvent-2B gene and counteracts terminal differentiation in Xenopus embryos.
The Xvent-2B promoter is regulated by a BMP-2/4-induced transcription complex comprising Smad signal transducers and specific transcription factors. Using a yeast one-hybrid screen we have found that Oct-25, a Xenopus POU domain protein related to mammalian Oct-3/4, binds as an additional factor to the Xvent-2B promoter. This interaction was further confirmed by both in vitro and in vivo analyses. The Oct-25 gene is mainly transcribed during blastula and gastrula stages in the newly forming ectodermal and mesodermal germ layers. Luciferase reporter gene assay demonstrated that Oct-25 stimulates transcription of the Xvent-2B gene. This stimulation depends on the Oct-25 binding site and the bone morphogenetic protein-responsive element. Furthermore, Oct-25 interacts in vitro with components of the Xvent-2B transcription complex, like Smad1/4 and Xvent-2. Overexpression of Oct-25 results in anterior/posterior truncations and lack of differentiation for neuroectoderm- and mesoderm-derived tissues including blood cells. This effect is consistent with an evolutionarily conserved role of class V POU factors in the maintenance of an undifferentiated cell state. In Xenopus, the molecular mechanism underlying this process might be coupled to the expression of Xvent proteins.
Cao
Ying
Y
Abteilung Biochemie, Universität Ulm, Albert-Einstein-Allee 11, D-89081, Germany.
Knöchel
Sigrun
S
Donow
Cornelia
C
Miethe
Josef
J
Kaufmann
Eckhard
E
Knöchel
Walter
W
D000818:Animals; D001483:Base Sequence; D001757:Blastomeres / Q000166:cytology / Q000502:physiology; D002454:Cell Differentiation; D003001:Cloning, Molecular; D018983:DNA Footprinting; D017931:DNA Primers; D003850:Deoxyribonuclease I; D004625:Embryo, Nonmammalian / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics*; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics*
D017931:DNA Primers; D018398:Homeodomain Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C099992:ventx2.1 protein, Xenopus; D003850:Deoxyribonuclease I