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Rap2 is required for Wnt/β‐catenin signaling pathway in Xenopus early development
Author(s) -
Choi SunCheol,
Han JinKwan
Publication year - 2005
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600571
Subject(s) - wnt signaling pathway , biology , xenopus , ectopic expression , microbiology and biotechnology , gene knockdown , frizzled , beta catenin , catenin , lrp6 , lrp5 , mesoderm , signal transduction , convergent extension , small gtpase , genetics , embryonic stem cell , gene , embryogenesis , gastrulation , embryo
The Wnt/β‐catenin signaling pathway is critical for the establishment of organizer and embryonic body axis in Xenopus development. Here, we present evidence that Xenopus Rap2, a member of Ras GTPase family, is implicated in Wnt/β‐catenin signaling during the dorsoventral axis specification. Ectopic expression of XRap2 can lead to neural induction without mesoderm differentiation. XRap2 dorsalizes ventral tissues, inducing axis duplication, organizer‐specific gene expression and convergent extension movements. Knockdown of XRap2 causes ventralized phenotypes including shortened body axis and defective dorsoanterior patterning, which are associated with aberrant Wnt signaling. In line with this, XRap2 depletion inhibits β‐catenin stabilization and the induction of ectopic dorsal axis and Wnt‐responsive genes caused by XWnt8, Dsh or β‐catenin, but has no effect on the signaling activities of a stabilized β‐catenin. Its knockdown also disrupts the vesicular localization of Dsh, thereby inhibiting Dsh‐mediated β‐catenin stabilization and the membrane recruitment and phosphorylation of Dsh by frizzled signaling. Taking together, we suggest that XRap2 is involved in Wnt/β‐catenin signaling as a modulator of the subcellular localization of Dsh.