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Zhen Li, Sumin Gu, Jean X Jiang; Embryonic Chick Lens Serves as an in vivo Model for Studying Congenital Cataract Mutations. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2854.
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© ARVO (1962-2015); The Authors (2016-present)
Congenital cataracts are lens opacity found at birth and most of these cataracts have been related to gene mutations in the lens. To date, 44 loci have been linked to congenital cataracts, but the underlying mechanism remains largely unknown. This is likely caused by a lack of effective model system, which mimics lens microenvironment in situ. Here we tested various cataract mutants using an embryonic chick lens model with retroviral expression and showed that this model closely mimics cataract formation and lens structure changes as a result of mutant expression.
Three congenital cataract mutants, chick connexin (Cx) 50E48K, human aquaporin 0 (AQP0) R33C, and human αA-crystalline (CRYAA) R54C, were reconstructed into a RCAS(A) retroviral vector. The retroviral constructs containing different mutants were injected into the lumen of embryonic chick lens at 68 hours of embryonic development. At embryonic day (E) 14 and 20, lens injected with mutants or vehicle were collected, and photographed under darkfield illumination. Lens were then fixed and paraffin and frozen tissue sections were prepared. Histochemical assays with hematoxylin and eosin staisning and immunofluorescence were performed.
Cataract formation was observed in lenses injected with Cx50E48K mutant at E14, but not in lenses injected with vehicle or wild type Cx50. Histochemical studies revealed that Cx50E48K expression led to disorganized nuclei and vacuoles. The severity of cataract formation was related to the amount and location of expression of the mutant. Both human mutants, AQP0R33C and CRYAAR54C, also resulted in cataract formation in this model. The cataracts were detected in mutant, but not in WT expressed E20 chick lens, Human AQP0R33C expression exhibited cortical cataract formation and also enlargement of extracellular spaces and fiber distortion at E20. A posterior capsule cataract was more prominent in human CRYAAR54C injected chick lens.
Retroviral expression of congenital mutant genes in embryonic chick lens closely mimics human congenital cataracts and lens morphological changes in situ. This model will likely provide a fast and reliable tool to investigate the development and underlying mechanism of congenital cataracts.
This is a 2020 ARVO Annual Meeting abstract.
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