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K. Varadaraj, S.S. Kumari, A. Shiels, R.T. Mathias; Transgenic Expression of AQP1 in Fiber Cells of Lenses From Wild Type and AQP0 Deficient Mice . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1843.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Lens water transport is mediated by AQP1 in epithelial cells and AQP0 in fiber cells. The functional significance of two different aquaporins is poorly understood. However, AQP0 is clearly important, as heterozygous knockout causes an age dependent nuclear cataract. The purpose of this investigation was to determine if replacement of AQP0 with AQP1 would restore water permeability and rescue the cataract in AQP0+/– lenses. Methods: Transgenic mice that express AQP1 in lens fiber cells were generated using the αA–crystallin promoter with a GFP tag. Transgenic founders were first identified by genotyping, then they were screened for positive expression using the Dark Reader special light and filter sets, immunostaining, and Western blotting. Founders were bred to generate homozygous transgenic (Tg–AQP1+/+) mice. To generate the double heterozygous (Tg–AQP1+/–/AQP0+/–), AQP0–/– mice were crossed with Tg–AQP1+/+ mice. Results: Lenses from transgenic mice expressing AQP1 in their fiber cells appeared normal although fiber cell water permeability was increased by 25–50 µm/s (Tg–AQP1+/–) and 50–100 µm/s (Tg–AQP1+/+). Fiber cell membrane water permeability in AQP0+/– lenses was reduced to about 60% of WT, and the lenses developed an age dependent cataract. However, in Tg–AQP1+/–/AQP0+/– lenses, fiber cell water permeability was significantly increased and the age dependent cataract did not develop. Conclusions: These data suggest that AQP1 and AQP0 have a similar function as a water transporter, and that function is critical for lens homeostasis. In addition to being a water transporter, AQP0 may have unique roles that were adequately fulfilled by the AQP0 protein present in the AQP0+/– lenses; these studies did not address this possibility.
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