CTNND1 variants cause familial exudative vitreoretinopathy through the Wnt/cadherin axis
Mu Yang, Shujin Li, Li Huang, Rulian Zhao, Erkuan Dai, Xiaoyan Jiang, Yunqi He, Jinglin Lu, Li Peng, Wenjing Liu, Zhaotian Zhang, Dan Jiang, Yi Zhang, Zhilin Jiang, Yeming Yang, Peiquan Zhao, Xianjun Zhu, Xiaoyan Ding, Zhenglin Yang
Mu Yang, Shujin Li, Li Huang, Rulian Zhao, Erkuan Dai, Xiaoyan Jiang, Yunqi He, Jinglin Lu, Li Peng, Wenjing Liu, Zhaotian Zhang, Dan Jiang, Yi Zhang, Zhilin Jiang, Yeming Yang, Peiquan Zhao, Xianjun Zhu, Xiaoyan Ding, Zhenglin Yang
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Research Article Genetics Ophthalmology

CTNND1 variants cause familial exudative vitreoretinopathy through the Wnt/cadherin axis

Abstract

Familial exudative vitreoretinopathy (FEVR) is a hereditary disorder that can cause vision loss. CTNND1 encodes a cellular adhesion protein p120-catenin (p120), which is essential for vascularization with unclear function in postnatal physiological angiogenesis. Here, we applied whole-exome sequencing to 140 probands of FEVR families and identified 3 candidate variants in the human CTNND1 gene. We performed inducible deletion of Ctnnd1 in the postnatal mouse endothelial cells (ECs) and observed typical phenotypes of FEVR with reactive gliosis. Using unbiased proteomics analysis combined with experimental approaches, we conclude that p120 is critical for the integrity of adherens junctions (AJs) and that p120 activates Wnt signaling activity by protecting β-catenin from glycogen synthase kinase 3 beta–ubiqutin–guided (Gsk3β-ubiquitin–guided) degradation. Treatment of CTNND1-depleted human retinal microvascular ECs with Gsk3β inhibitors LiCl or CHIR-99021 enhanced cell proliferation. Moreover, LiCl treatment increased vessel density in Ctnnd1-deficient mouse retinas. Variants in CTNND1 caused FEVR by compromising the expression of AJs and Wnt signaling activity. Genetic interactions between p120 and β-catenin or α-catenin revealed by double-heterozygous deletion in mice showed that p120 regulates vascular development through the Wnt/cadherin axis. In conclusion, variants in CTNND1 can cause FEVR through the Wnt/cadherin axis.

Authors

Mu Yang, Shujin Li, Li Huang, Rulian Zhao, Erkuan Dai, Xiaoyan Jiang, Yunqi He, Jinglin Lu, Li Peng, Wenjing Liu, Zhaotian Zhang, Dan Jiang, Yi Zhang, Zhilin Jiang, Yeming Yang, Peiquan Zhao, Xianjun Zhu, Xiaoyan Ding, Zhenglin Yang

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Figure 9

Functional consequences of CTNND1 variant alleles.

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Functional consequences of CTNND1 variant alleles. (A) Western blot anal...
(A) Western blot analysis of protein levels of overexpressed FLAG-p120 and endogenous β-catenin, α-catenin, c-Myc, and CyclinD1 in HEK293T cells transfected with wild-type (WT), variant, or vector plasmids. (B–E) Quantification of relative protein levels of endogenous β-catenin, α-catenin, c-Myc, and CyclinD1 in HEK293T cells transfected with WT, variant, or vector plasmids. The P values are from multiple comparisons in 1-way ANOVA with Dunnett’s multiple comparisons test (n = 3); **P < 0.01, ***P < 0.001, ****P < 0.0001. (F) Schematic diagram of p120 protein. p120 consists of 10 armadillo repeat (ARM) domains flanked by N-terminal (NTD) and C-terminal (CTD) domains. The potential binding surfaces for cadherins are indicated with black lines. The locations of mutated residues are indicated with black arrows. (G) Western blot analysis of FLAG-p120 (WT, variant, or vector) co-immunoprecipitated with HA-VE-cadherin (HA-VE-cad) or endogenous β-catenin. An empty vector was used as negative control. Experiments were performed at least 3 times independently.