Bone Morphogenetic Protein Antagonism of Spemann's Organizer Is Independent of Wnt Signaling

AbstractTheXenopushomeobox genetwinis involved in the Wnt-mediated induction of Spemann's organizer. Additionally, several lines of evidence indicate that bone morphogenetic proteins (BMPs) play a role in repressing the formation of the organizer by antagonizing the expression of genes involved in organizer establishment. In order to determine at what level BMPs exert their effect, we measured the activity of different genes expressed within the organizer region. We report that BMP signaling can antagonize the induction of the dorsal-specific genegoosecoidbut is unable to affect Wnt signaling at the level oftwin.These results suggest that the antagonistic activities of BMPs in organizer formation occur postzygotically, independent oftwinregulation, and that Wnt-like dorsal determinant signaling pathways do not crosstalk with BMPs