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David M Wu, Xuke J Ji, Brian Palmer Hafler, Yunlu Xue, Sophia Zhao, Parimal Rana, Wenjun Xiong, Connie Cepko; Overexpression of human Nrf2 rescues cone photoreceptors and retinal pigment epithelial cells from degeneration in the rd1 mouse. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4503.
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© ARVO (1962-2015); The Authors (2016-present)
Overexpression of mouse Nrf2 in the rd1 mouse, a model of retinitis pigmentosa, results in rescue of cones and retinal pigment epithelial cells. The next step towards evaluating the potential for Nrf2 for human disesae therapy is to assess its ability to rescue retinal degeneration in larger animals. In planning such studies, it would be useful to know whether the product of the human Nrf2 gene is able to rescue across species, since this is the gene product of most interest in the development of human therapies.
An AAV 2/8 was constructed using a CMV promoter and human-beta globin intron to drive expression of the human Nrf2 gene (AAV 2/8 CMV human Nrf2). A construct with the same promoter complex encoding GFP strongly drives GFP expression in cone photoreceptors and retinal pigment epithelial cells in mouse retina (AAV 2/8 CMV GFP). The AAV 2/8 driving the human Nrf2 gene was delivered to the subretinal space of rd1 mouse eyes at p0. For controls, some eyes were left uninjected and other eyes were injected with AAV 2/8 with the same promoter complex driving GFP or mouse Nrf2 gene (AAV 2/8 CMV mouse Nrf2). The mice were sacrificed at P40 or P70. Cones were identified by immunostaining for cone arrestin and retinal pigment epithelial cells were identified by phalloidin.
All rd1 eyes at P40 and P70 showed evidence of retinal degeneration, with cone and retinal pigment epithelial cell loss higher in the central eye compared to the peripheral eye. However, there was significantly less loss in eyes infected with AAV 2/8 CMV human Nrf2 or AAV 2/8 mouse Nrf2 than in those that had been uninjected, or injected with AAV 2/8 CMV GFP. There was not a marked difference in eyes receiving AAV 2/8 CMV human Nrf2 compared to AAV 2/8 CMV mouse Nrf2.
Overexpression of human Nrf2 in the degenerating eyes of rd1 mice rescues cone photoreceptors and retinal pigment epithelial cells. There is significant homology between the coding sequence and protein sequence for human and mouse Nrf2 (83 and 82% respectively). Given that sequence homology is similar or greater in Nrf2 genes from large animals (89% in dogs and 99% in rhesus monkeys) that may be utilized in studies to evaluate Nrf2 as a potential therapeutic gene for human gene therapy trials, these results suggest that it may be feasible to assess rescue by the human Nrf2 gene across species.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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