The best characterized non-canonical pathway is the Dishevelled-dependent “Planar Cell Polarity” (PCP) pathway. Wnt11 family ligands signal through non-canonical Wnt signaling pathways (Tada and Smith, 2000), which do not involve beta-catenin. Signaling downstream of Wnt11 family ligands is complex and involves multiple membrane receptors and cytosolic proteins (Sumanas and Ekker, 2001 Wallingford, 2012). However, the specific requirement for these ligands during gastrulation has not been fully assessed by knock-down or knock-out perturbation in amphibians. Signaling mediated by Wnt11 family ligands is known to play an important role in gastrulation and anterior-posterior axis extension in all vertebrates that have been studied (Andre et al., 2015 Hardy et al., 2008 Heisenberg et al., 2000 Kilian et al., 2003 Matsui et al., 2005 Tada and Smith, 2000 Yamaguchi et al., 1999). We were aided in our interpretation of the immunofluorescence by the novel, membrane proximal location of the cleavage furrow protein anillin in the epithelium of the blastopore lip and early archenteron. We found that the initial extension of the archenteron is correlated with blastopore lip maturation, and archenteron extension is dramatically disrupted by decreased Wnt11 family signaling. We connected these externally visible phenotypes to cellular events in the internal tissues by imaging intact fixed embryos stained for anillin and microtubules. Using dark field illuminated time-lapse imaging and kymograph analysis, we identified a failure of dorsal blastopore lip maturation that correlated with slower blastopore closure and failure to internalize the endoderm at the dorsal blastopore lip. In response to their very similar gastrulation phenotypes, we chose to characterize dual morphants. Single morphants exhibited very similar phenotypes of delayed blastopore closure, but they had different phenotypes during the tailbud period. We knocked down Wnt11b and Wnt11, separately and together, in Xenopus laevis. Non-mammalian vertebrate genomes encode two Wnt11 family proteins whose distinct functions have been unclear. Loss of function causes defects in gastrulation and/or anterior-posterior axis extension in all vertebrates. Wnt11 family proteins are ligands that activate a type of Dishevelled-mediated, non-canonical Wnt signaling pathway.
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