Wnt ligands from the embryonic surface ectoderm regulate 'bimetallic strip' optic cup morphogenesis in mouse.
Bottom Line: Consistent with this, microarray and cell fate marker analysis identified a series of expression changes in genes known to be regulated by RA or by the Wnt/β-catenin pathway.Using pathway reporters, we showed that Wnt ligands from the surface ectoderm directly or indirectly elicit a Wnt/β-catenin response in retinal pigment epithelium (RPE) progenitors near the optic cup rim.These data thus establish a novel hypothesis to explain how differential cell numbers in a bilayered epithelium can lead to shape change.
Affiliation: Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.Show MeSH
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Mentions: Whole-mount E13.5 eyes viewed axially show a ventral coloboma that reflects the failure of the ventral choroidal fissure to close (Fig. 3A-D). In addition, the distal boundary of pigmentation in the control and Le-cre; Wlsfl/fl eyes differs. In section, the Le-cre; Wlsfl/fl mice show an eye ‘cup' that is more saucer-shaped at E11.5 (Fig. 2H) and E12.5 (Fig. 2J). This change is very obvious at E13.5 when eyes are viewed laterally in whole-mount (Fig. 3E-H). In control eyes the RPE wraps around the eye cup (Fig. 3E,G), but in Le-cre; Wlsfl/fl mice the saucer-shaped RPE does not extend distally around the eye cup (Fig. 3F,H). By E13.5, Le-cre; Wlsfl/fl mice also show extrusion of lens material to the exterior (Fig. 3F,H). The ventral coloboma of the Le-cre; Wlsfl/fl mice is apparent in much of this analysis (see also Fig. 4B,D, Fig. 5B,D and Fig. 7I,J) and is one feature of the phenotype similar to that of Lrp6 mutant mice (Zhou et al., 2008). These changes in eye development indicate that Wnt ligands produced by the surface ectoderm have a crucial role in eye development and influence morphogenesis of both the mesenchyme and the eye cup.Fig. 3.
Affiliation: Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.