Catenin α 1 mutations cause familial exudative vitreoretinopathy by overactivating Norrin/β-catenin signaling
Xianjun Zhu, … , Weiquan Zhu, Zhenglin Yang
Xianjun Zhu, … , Weiquan Zhu, Zhenglin Yang
Published January 26, 2021
Citation Information: J Clin Invest. 2021;131(6):e139869. https://doi.org/10.1172/JCI139869.
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Research Article Angiogenesis Genetics

Catenin α 1 mutations cause familial exudative vitreoretinopathy by overactivating Norrin/β-catenin signaling

Abstract

Familial exudative vitreoretinopathy (FEVR) is a severe retinal vascular disease that causes blindness. FEVR has been linked to mutations in several genes associated with inactivation of the Norrin/β-catenin signaling pathway, but these account for only approximately 50% of cases. We report that mutations in α-catenin (CTNNA1) cause FEVR by overactivating the β-catenin pathway and disrupting cell adherens junctions. We identified 3 heterozygous mutations in CTNNA1 (p.F72S, p.R376Cfs*27, and p.P893L) by exome sequencing and further demonstrated that FEVR-associated mutations led to overactivation of Norrin/β-catenin signaling as a result of impaired protein interactions within the cadherin-catenin complex. The clinical features of FEVR were reproduced in mice lacking Ctnna1 in vascular endothelial cells (ECs) or with overactivated β-catenin signaling by an EC-specific gain-of-function allele of Ctnnb1. In isolated mouse lung ECs, both CTNNA1-P893L and F72S mutants failed to rescue either the disrupted F-actin arrangement or the VE-cadherin and CTNNB1 distribution. Moreover, we discovered that compound heterozygous Ctnna1 F72S and a deletion allele could cause a similar phenotype. Furthermore, in a FEVR family, we identified a mutation of LRP5, which activates Norrin/β-catenin signaling, and the corresponding knockin mice exhibited a partial FEVR-like phenotype. Our study demonstrates that the precise regulation of β-catenin activation is critical for retinal vascular development and provides new insights into the pathogenesis of FEVR.

Authors

Xianjun Zhu, Mu Yang, Peiquan Zhao, Shujin Li, Lin Zhang, Lulin Huang, Yi Huang, Ping Fei, Yeming Yang, Shanshan Zhang, Huijuan Xu, Ye Yuan, Xiang Zhang, Xiong Zhu, Shi Ma, Fang Hao, Periasamy Sundaresan, Weiquan Zhu, Zhenglin Yang

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Figure 4

Conditional KO of Ctnna1 in mice causes severe retinal vascularization defects.

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Conditional KO of Ctnna1 in mice causes severe retinal vascularization d...
(A) DAPI staining of hyaloid vessels in the eyes of control and Ctnna1iECKO mice, showing that hyaloid vessel regression was markedly delayed in the eye. Scale bar: 250 μm. (B) Compared with those of littermate controls, P9 flat-mounted retinas of Ctnna1iECKO/+ mice showed delayed radial growth of the superficial vascular plexus, with moderate neovascularizations at the angiogenic front. Ctnna1iECKO retinas showed retarded vascular growth and hyperplasia of the primary vascular plexus. Vessels were stained with IB4 (red). Scale bar: 500 μm. (C) Frozen sections of retinas from P9 control, Ctnna1iECKO/+, and Ctnna1iECKO mice were costained with IB4 (red) and DAPI (blue). Scale bars: 25 μm. Vertical growth of the superficial retinal vascular plexus was delayed in Ctnna1iECKO/+ mice. In Ctnna1iECKO retinas, profound defects in vertical vascular growth into the deeper retinal layers were observed, and the vascular plexus became hyperplastic. No secondary or tertiary vessels were observed in these retinas. (D) VE-cadherin (green) and IB4 (red) staining of P9 Ctnna1iECKO and control retinas. VE-cadherin was disorganized in Ctnna1iECKO retinas. White dotted boxes indicate enlarged regions, detailed on the right. Scale bars: 25 μm and 10 μm (enlarged insets). (E) P9 flat-mounted Ctnna1iECKO retinas showed extensive leakage of Evans blue dye (white arrow) and visible, enlarged blood vessels (yellow arrow) compared with control retinas. (F) Ctnna1iECKO, Ctnna1iECKO/+, and control retinas were costained with IB4 (green) and Ter119 (red), revealing extensive leakage of erythrocytes (white arrowheads) in Ctnna1iECKO/+ and Ctnna1iECKO retinas. Scale bars: 25 μm. (G–I) Quantification of vascular progression, vascular density, and vessel leakage. Error bars indicate the SD. *P <0.05 and ****P < 0.0001, by 1-way ANOVA with Tukey’s multiple-comparison test (n ≥ 6). Experiments were performed independently at least 3 times.