Sahu Bhubanananda, Maeda Akiko
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, USA.
Methods Mol Biol. 2018;1753:89-102. doi: 10.1007/978-1-4939-7720-8_6.
The retinal pigmented epithelium (RPE) is a single layer of polarized epithelial cells which plays many important roles for visual function. One of such roles is production of visual chromophore, 11-cis-retinal through the visual cycle. The visual cycle consists of biochemical processes for regenerating chromophore by a collective action of the RPE and photoreceptor. Photoreceptors harbor the G protein-coupled receptors, opsin which enables to receive light when it bounds to 11-cis-retinal. With absorption of a photon of light, 11-cis-retinal photoisomerizes to all-trans-retinal. All-trans-retinal reduces to all-trans-retinol in the photoreceptor and further recycles back to 11-cis-retinal in the RPE. Acyltransferases and isomerohydrolase(s) along with retinol dehydrogenases sequentially convert all-trans-retinol to 11-cis-retinal in the RPE. Dysfunctions of any retinoid cycle enzymes in the RPE can cause retinal diseases. Phenotyping RPE functions by the use of mutant mouse models will provide great detailed biochemical insights of the visual cycle and further manipulative strategies to protect against retinal degeneration. Here, we describe biochemical analyses of the visual cycle in mouse models using RPE cells.
视网膜色素上皮（RPE）是一层极化的上皮细胞，对视觉功能起着许多重要作用。其中一个作用是通过视觉循环产生视觉发色团11-顺式视黄醛。视觉循环由RPE和光感受器共同作用使发色团再生的生化过程组成。光感受器含有G蛋白偶联受体视蛋白，当它与11-顺式视黄醛结合时能够接收光。随着一个光子的吸收，11-顺式视黄醛光异构化为全反式视黄醛。全反式视黄醛在光感受器中还原为全反式视黄醇，并在RPE中进一步循环回11-顺式视黄醛。酰基转移酶和异构水解酶与视黄醇脱氢酶一起在RPE中依次将全反式视黄醇转化为11-顺式视黄醛。RPE中任何类视黄醇循环酶的功能障碍都可能导致视网膜疾病。通过使用突变小鼠模型对RPE功能进行表型分析，将为视觉循环提供非常详细的生化见解，并为预防视网膜退化提供进一步的操纵策略。在这里，我们描述了使用RPE细胞对小鼠模型中视觉循环的生化分析。
