Coactivation of Rac and Rho by Wnt/Frizzled signaling is required for vertebrate gastrulation
- Raymond Habas1,2,
- Igor B. Dawid1, and
- Xi He2,3
Abstract
Wnt/Frizzled (Fz) signaling controls cell polarity/movements during vertebrate gastrulation via incompletely defined mechanisms. We demonstrated previously that Wnt/Fz activation of Rho, a GTPase and regulator of cytoskeletal architecture, is essential for vertebrate gastrulation. Here we report that in mammalian cells andXenopus embryos, Wnt/Fz signaling coactivates Rho and Rac, another GTPase and distinct regulator of cytoskeletal architecture. Wnt/Fz activation of Rac is independent of Rho and mediates Wnt/Fz activation of Jun N-terminal kinase (JNK). Dishevelled (Dvl), a cytoplasmic protein downstream of Fz, forms a Wnt-induced complex with Rac independent of the Wnt-induced Dvl–Rho complex. Depletion or inhibition of Rac function perturbs Xenopus gastrulation without affecting Wnt/Fz activation of the Rho or β-catenin pathway. We propose that parallel activation of Rac and Rho pathways by Wnt/Fz signaling is required for cell polarity and movements during vertebrate gastrulation.
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Footnotes
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↵3 Corresponding author.
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E-MAIL xi.he{at}tch.harvard.edu; FAX (617) 734-1646.
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Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.1022203.
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- Received July 9, 2002.
- Accepted November 15, 2002.
- Cold Spring Harbor Laboratory Press