Cataract-causing G91del mutant destabilised βA3 heteromers formation linking with structural stability and cellular viability
- 6 September 2021
- journal article
- research article
- Published by BMJ in British Journal of Ophthalmology
- Vol. 106 (10), 1473-1478
- https://doi.org/10.1136/bjophthalmol-2021-320033
Abstract
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.Keywords
Funding Information
- National Natural Science Foundation of China (31872724, 81900837, 82070939)
- Natural Science Foundation of Zhejiang Province for Distinguished Young Scholar (LR21H120001)
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