Ectopic activation of Wnt/β-catenin signaling in lens fiber cells results in microphthalmia and cataract.

(A) Schematic diagram of αA-CLEF transgenic construct. αA-crystallin promoter (αACRY) drives expression of the fusion protein containing the C-terminal transactivation domain of human β-catenin fused to the amino terminus of full-length mouse Lef1 and HA-tag. (B) RT-PCR analysis of the onset of transgenic mRNA. CLEF mRNA is fully detected in mutant eyes from E13.5 until onward. (C) CLEF transgenic protein is detected in mutant lenses (Tg) at E16.5 with anti-HA-tag antibody. (D, E) CLEF transgenic protein is detected with anti-Lef1 antibody in the central part of the fiber cell compartment of mutant lenses at E13.5. (F) qRT-PCR demonstrates relative change of gene expression in E16.5 αA-CLEF transgenic lenses. Expression of known Wnt/β-catenin signaling target genes – Axin2, Nkd1, Cyclin D1 and Cyclin D2 is upregulated in E16.5 αA-CLEF lenses compared to wild-type, (**p<0.01). (G-N) Ocular phenotype of wild-type (G, I, K, M) and αA-CLEF (H, J, L, N) mice. (G, H). Adult transgenic mice develop microphthalmia and cataract. (I, J) Dissected lenses from P14 transgenic mouse are already smaller (J) compared to wild-type lenses (I) and visible cataract is already present in P14 transgenic lenses (J). (K-N) Histological sections of adult wild-type (K) and transgenic (M) eyes and detail view of wild-type (M) and αA-CLEF (N) lens equatorial region. Disorganized fiber cell nuclei and vacuoles are present in the equatorial region of transgenic lens (N). Scale bars indicate (D, E) 50 µm, (K, L) 400 µm, and (M, N) 100 µm. Abbreviations: fc, fiber cell compartment; eq, equatorial region.