Background/aims Congenital cataracts, which are genetically heterogeneous eye disorders, result in visual loss in childhood around the world. CRYBA1/BA3 serves as an abundant structural protein in the lens, and forms homomers and heteromers to maintain lens transparency. In previous study, we identified a common cataract-causing mutation, βA3-glycine at codon 91 (G91del) (c.271–273delGAG), which deleted a highly conserved G91del and led to perinuclear zonular cataract. In this study, we aimed to explore the underlying pathogenic mechanism of G91del mutation.
Methods Protein purification, size-exclusion chromatography, spectroscopy and molecular dynamics simulation assays were used to investigate the effects on the heteromers formation and the protein structural properties of βA3-crystallin caused by G91del mutation. Intracellular βA3-G91del overexpression, MTT (3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide) and cell apoptosis were used to investigate the cellular functions of βA3-G91del.
Results βA3-crystallin and βB2-crystallin could form heteromers, which have much more stable structures than βA3 homomers. Interestingly, βA3/βB2 heteromers improved their resistance against the thermal stress and the guanidine hydrochloride treatment. However, the pathogenic mutation βA3-G91del destroyed the interaction with βB2, and thereby decreased its structural stability as well as the resistance of thermal or chemical stress. What’s more, the βA3-G91del mutation induced cell apoptosis and escaped from the protection of βB2-crystallin.
Conclusions βA3/βB2 heteromers play an indispensable role in maintaining lens transparency, while the βA3-G91del mutation destabilises heteromers formation with βB2-crystallin, impairs cellular viability and induces cellular apoptosis. These all might contribute to cataract development.
- experimental – laboratory
- lens and zonules
Data availability statement
All data relevant to the study are included in the article or uploaded as online supplemental information.
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Contributors KY and XC conceived, designed and supervised the research. HW and QT performed the experiments. XC, JX and WX performed data analyses. HW wrote the manuscript.
Funding This work was supported by the National Natural Science Foundation of China (No. 31872724, No.82070939 and No. 81900837) and the Natural Science Foundation of Zhejiang Province for Distinguished Young Scholar (No. LR21H120001).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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