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: Wnt responses are implicated in early eye development (Smith et al., 2005; Fuhrmann, 2008; Swindell et al., 2008; Zhou et al., 2008). To define the ligand genes expressed in eye tissues that were Cre targetable, we flow sorted GFP+ cells from Z/EG mice (Novak et al., 2000) converted by Le-cre (Ashery-Padan et al., 2000) and Wnt1-cre (Brault et al., 2001); these identify, respectively, ocular ectoderm and neural crest-derived POM cells according to antibody labeling for GFP in cryosections (Fig. 1A,C). Flow sorting of GFP+ cells from dissected eye regions from E10.5 showed well separated populations (Fig. 1B,D). End-point RT-PCR on mRNA isolated from these GFP+ populations showed that many Wnt ligands were expressed. Ectoderm expressing Le-cre expressed the majority of the Wnt ligand family, including Wnt1, 2, 3, 3a, 4, 5a, 6, 9b, 10a, 10b and 11 (Fig 1E). Sorted neural crest-derived POM cells expressed mRNA for Wnt2b, 3, 3a, 5a, 7b, 9a, 9b, 10 and 11 (Fig 1E).Fig. 1.
Affiliation: Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.