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Genes Dev January 15, 2003; 17 (2): 295-309.

Coactivation of Rac and Rho by Wnt/Frizzled signaling is required for vertebrate gastrulation.

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 and Xenopus 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 beta-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.

PubMed ID: 12533515
PMC ID: PMC195976
Article link: Genes Dev
Grant support: [+]

Species referenced: Xenopus
Genes referenced: akt1 dvl2 jun rac1 rho rho.2
Morpholinos: rac1 MO1

References [+] :
Adler, Planar signaling and morphogenesis in Drosophila. 2002, Pubmed