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Identification and functional analysis of two GJA8 variants in Chinese families with eye anomalies

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Abstract

In this study, we report on two different GJA8 variants related to congenital eye anomalies in two unrelated families, respectively. GJA8 (or Cx50) encoding a transmembrane protein to form lens connexons has been known as a common causative gene in congenital cataracts and its variants have recently been reported related to a wide phenotypic spectrum of eye defects. We identified two GJA8 variants, c.134G>T (p.Try45Leu, W45L) detected in a cataract family by Sanger sequencing and c.281G>A (p.Gly94Glu, G94E) found in a family with severe eye malformations including microphthalmia by whole-exome sequencing. These two variants were absent in healthy population and predicted deleterious by bioinformatic analysis. Furthermore, we compared the expression in cell lines between these mutants and the wildtype to explore their potential mechanism. Cell counting kit-8 assay showed that overexpression of either W45L or G94E decreased cell viability compared with wild-type Cx50 and the control. A lower protein level in W45L found by western blotting and fewer punctate fluorescent signals showed by fluorescence microscopy suggested that W45L may have less protein expression. A higher G94E protein level and abundant dotted distribution indicated that G94E may cause aberrant protein degradation and accumulation. Such results from in vitro assays confirmed the impact of these two variants and gave us a hint about their different pathogenic roles in different phenotypes. In conclusion, our study is the first to have the functional analysis of two GJA8 variants c.134G>T and c.281G>A in Chinese pedigrees and explore the impact of these variants, which can help in prenatal diagnosis and genetic counseling as well in basic studies on GJA8.

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Acknowledgements

We appreciated all the volunteers for participating in this study. This project was supported by the Ministry of Science and Technology of China (2021YFA1101300 and 2020YFA0112500), the National Key basic Research Program of China (973 Program 2015CB964601), and the National Nature Science Foundation of China (81371062).

Funding

The Ministry of Science and Technology of China, Grant/Award Number: 2021YFA1101300 and 2020YFA0112500; the National Key Basic Research Program of China (973 Program 2015CB964601) and the National Nature Science Foundation of China (81371062).

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Authors and Affiliations

  1. Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai, 200434, China

    Linlin Zhou, Xuejiao Sun, Xinyao Wang, Kangyu Liu, Zilin Zhong & Jianjun Chen

  2. Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China

    Linlin Zhou, Xuejiao Sun, Xinyao Wang, Kangyu Liu, Zilin Zhong & Jianjun Chen

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  1. Linlin Zhou
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Correspondence to Jianjun Chen.

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Communicated by Shuhua Xu.

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Zhou, L., Sun, X., Wang, X. et al. Identification and functional analysis of two GJA8 variants in Chinese families with eye anomalies. Mol Genet Genomics 297, 1553–1564 (2022). https://doi.org/10.1007/s00438-022-01939-6

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