Functional differences between Tcf1 isoforms in early Xenopus development.

In Xenopus gastrula stage embryos, four isoforms of Tcf1 (B, C, D and E) are present with high amino acid sequence conservation compared to fish, mice and human. We studied possible functional differences between these Tcf1 isoforms during early Xenopus development. After overexpression of single Tcf1 isoforms, two distinct phenotypes were observed.

The E3 ligase RNF43 inhibits Wnt signaling downstream of mutated β-catenin by sequestering TCF4 to the nuclear membrane.

Given its fundamental role in development and cancer, the Wnt-β-catenin signaling pathway is tightly controlled at multiple levels. RING finger protein 43 (RNF43) is an E3 ubiquitin ligase originally found in stem cells and proposed to inhibit Wnt signaling by interacting with the Wnt receptors of the Frizzled family. We detected endogenous RNF43 in the nucleus of human intestinal crypt and colon cancer cells.

The Wnt signaling mediator tcf1 is required for expression of foxd3 during Xenopus gastrulation.

TCF1 belongs to the family of LEF1/TCF transcription factors that regulate gene expression downstream of Wnt/β-catenin signaling, which is crucial for embryonic development and is involved in adult stem cell regulation and tumor growth. In early Xenopus embryos, tcf1 plays an important role in mesoderm induction and patterning. Foxd3 emerged as a potential tcf1 target gene in a microarray analysis of gastrula stage embryos.

Lef1 plays a role in patterning the mesoderm and ectoderm in Xenopus tropicalis.

Tcf/Lef HMG box transcription factors are nuclear effectors of the canonical Wnt signaling pathway, which function in cell fate specification. Lef1 is required for the development of tissues and organs that depend on epithelial mesenchymal interactions. Here, we report the effects of lef1 loss of function on early development in X.

Cloning, embryonic expression, and functional characterization of two novel connexins from Xenopus laevis.

Vertebrate gap junctions are constituted of connexin (Cx) proteins. In Xenopus laevis, only seven different Cxs have been described so far. Here, we identify two new Cxs from X.