Van Hooser J Preston, Liang Yan, Maeda Tadao, Kuksa Vladimir, Jang Geeng-Fu, He Yu-Guang, Rieke Fred, Fong Henry K W, Detwiler Peter B, Palczewski Krzysztof
Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA.
J Biol Chem. 2002 May 24;277(21):19173-82. doi: 10.1074/jbc.M112384200. Epub 2002 Mar 15.
The visual process is initiated by the photoisomerization of 11-cis-retinal to all-trans-retinal. For sustained vision the 11-cis-chromophore must be regenerated from all-trans-retinal. This requires RPE65, a dominant retinal pigment epithelium protein. Disruption of the RPE65 gene results in massive accumulation of all-trans-retinyl esters in the retinal pigment epithelium, lack of 11-cis-retinal and therefore rhodopsin, and ultimately blindness. We reported previously (Van Hooser, J. P., Aleman, T. S., He, Y. G., Cideciyan, A. V., Kuksa, V., Pittler, S. J., Stone, E. M., Jacobson, S. G., and Palczewski, K. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8623-8628) that in Rpe65-/- mice, oral administration of 9-cis-retinal generated isorhodopsin, a rod photopigment, and restored light sensitivity to the electroretinogram. Here, we provide evidence that early intervention by 9-cis-retinal administration significantly attenuated retinal ester accumulation and supported rod retinal function for more than 6 months post-treatment. In single cell recordings rod light sensitivity was shown to be a function of the amount of regenerated isorhodopsin; high doses restored rod responses with normal sensitivity and kinetics. Highly attenuated residual rod function was observed in untreated Rpe65-/- mice. This rod function is likely a consequence of low efficiency production of 11-cis-retinal by photo-conversion of all-trans-retinal in the retina as demonstrated by retinoid analysis. These studies show that pharmacological intervention produces long lasting preservation of visual function in dark-reared Rpe65-/- mice and may be a useful therapeutic strategy in recovering vision in humans diagnosed with Leber congenital amaurosis caused by mutations in the RPE65 gene, an inherited group of early onset blinding and retinal degenerations.
视觉过程由11-顺式视黄醛向全反式视黄醛的光异构化引发。为了维持视觉，必须从全反式视黄醛再生11-顺式发色团。这需要RPE65，一种主要的视网膜色素上皮蛋白。RPE65基因的破坏导致全反式视黄酯在视网膜色素上皮中大量积累，缺乏11-顺式视黄醛，因此也缺乏视紫红质，最终导致失明。我们之前报道过（Van Hooser, J. P., Aleman, T. S., He, Y. G., Cideciyan, A. V., Kuksa, V., Pittler, S. J., Stone, E. M., Jacobson, S. G., and Palczewski, K. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8623 - 8628），在Rpe65基因敲除小鼠中，口服9-顺式视黄醛可生成视紫红质，一种视杆光色素，并恢复视网膜电图的光敏感性。在此，我们提供证据表明，通过给予9-顺式视黄醛进行早期干预可显著减轻视网膜酯积累，并在治疗后6个月以上维持视杆视网膜功能。在单细胞记录中，视杆光敏感性显示为再生视紫红质量的函数；高剂量可恢复具有正常敏感性和动力学的视杆反应。在未治疗的Rpe65基因敲除小鼠中观察到高度减弱的残余视杆功能。如类视黄醇分析所示，这种视杆功能可能是视网膜中全反式视黄醛光转化生成11-顺式视黄醛效率低下的结果。这些研究表明，药物干预可在暗饲养的Rpe65基因敲除小鼠中长期维持视觉功能，并且可能是一种有用的治疗策略，用于恢复因RPE65基因突变导致的Leber先天性黑蒙症患者的视力，这是一组遗传性早发性失明和视网膜变性疾病。
