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. Author manuscript; available in PMC: 2021 Dec 1.
Published in final edited form as: Exp Eye Res. 2020 Oct 9;201:108231. doi: 10.1016/j.exer.2020.108231

Figure 2.

Figure 2.

The role of the canonical Wnt/β Catenin pathway in bi-directional signaling determining corneal epithelial cell fate. (A) In the WT mouse, transcription factor Pitx2 is necessary for the expression of Dkk2, which is confined to the mesenchyme at E11.5, but present in both the epithelium and POM at E14.5, and continues to be expressed in these tissues post natally. Dkk2 from these sources antagonizes Wnt/β catenin signaling in the epithelium and POM. Pax6 expression is observed in the epithelium and leads to the expression of corneal specific markers, including K3 and K12. (B) When Dkk2, or the upstream Pitx2, are genetically knocked-down, Wnt/β catenin signaling persists without Dkk2 antagonism. Upregulation of markers of Wnt signaling such as Axin2 are observed in the POM and epithelium, and Pax6 is suppressed in the epithelium. Due to an absence of Pax6, a conjunctival phenotype is observed as early as E16.5.