Identification of Wnt/β-catenin modulated genes in the developing retina

Purpose: During mammalian eye development, the restriction of Wnt/β-catenin signaling at the junction of the neural retina and the retinal pigment epithelium in the peripheral eyecup is required for the development of the ciliary margin, a non-neural region of the eyecup that is the precursor of the ciliary body and iris of the adult eye. Methods: To identify genes that are modulated by β-catenin activity in the embryonic retina, we performed gene expression profiling in Li+-treated retinal explants, a pharmacological model of β-catenin activation. The Li+-modulated gene data set was searched for β-catenin/T-cell specific transcription factor binding sites. Results: Functional annotations of this data set revealed significant enrichments for genes involved in chromatin organization, neurogenesis, and cell motion/migration. Quantitative real-time polymerase chain reaction (qRT–PCR) analysis confirmed the modulation of 12 genes in Li+-treated explants and retinas of mice with Cre-mediated induction of constitutively active β-catenin (β-catact). In situ hybridization revealed β-catenin-specific upregulation of cyclindependent kinase inhibitor 1A (P21) [Cdkn1a] and tumor necrosis factor receptor superfamily, member 19 (Tnfrsf19) in the developing retina consistent with the antineurogenic and proliferation changes associated with ectopic Wnt/β-catenin signaling in the eyecup. Conclusions: This data set of Li+-modulated genes provides a valuable resource for characterizing the Wnt/ β-catenin