Tcf-1 expression during Xenopus development.

We report the cloning and expression of Xenopus Tcf-1. The amino acid sequence of Tcf-1 of Xenopus laevis and Xenopus tropicalis is closely related to that of chicken, mouse and man. Thus, the family of Tcf/Lef proteins in the amphibian Xenopus comprises four members as in higher vertebrates.

Lef-1 and Tcf-3 transcription factors mediate tissue-specific Wnt signaling during Xenopus development.

Wnt signaling functions repeatedly during embryonic development to induce different but specific responses. What molecular mechanisms ensure that Wnt signaling triggers the correct tissue-specific response in different tissues? Early Xenopus development is an ideal model for addressing this fundamental question, since there is a dramatic change in the response to Wnt signaling at the onset of zygotic gene transcription: Wnt signaling components encoded by maternal mRNA establish the dorsal embryonic axis; zygotically expressed Xwnt-8 causes almost the opposite, by promoting ventral and lateral and restricting dorsal mesodermal development. Although Wnt signaling can function through different signal transduction cascades, the same beta-catenin-dependent, canonical Wnt signal transduction pathway mediates Wnt signaling at both stages of Xenopus development.

Molecular cloning, genetic mapping, and developmental expression of bovine POU5F1.

We describe isolation and characterization of the bovine ortholog of POU5F1 (bPOU5F1) encoding octamer-binding transcription factor-4 (Oct-4). The organization of bPOU5F1 is similar to its human and murine orthologs, and it shares 90.6% and 81.