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Vitamin A Derivatives as Treatment Options for Retinal Degenerative Diseases
Department of Ophthalmology & Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA
* Author to whom correspondence should be addressed.
Received: 7 May 2013; in revised form: 5 June 2013 / Accepted: 13 June 2013 / Published: 12 July 2013
Abstract: The visual cycle is a sequential enzymatic reaction for vitamin A, all-trans-retinol, occurring in the outer layer of the human retina and is essential for the maintenance of vision. The central source of retinol is derived from dietary intake of both retinol and pro-vitamin A carotenoids. A series of enzymatic reactions, located in both the photoreceptor outer segment and the retinal pigment epithelium, transform retinol into the visual chromophore 11-cis-retinal, regenerating visual pigments. Retina specific proteins carry out the majority of the visual cycle, and any significant interruption in this sequence of reactions is capable of causing varying degrees of blindness. Among these important proteins are Lecithin:retinol acyltransferase (LRAT) and retinal pigment epithelium-specific 65-kDa protein (RPE65) known to be responsible for esterification of retinol to all-trans-retinyl esters and isomerization of these esters to 11-cis-retinal, respectively. Deleterious mutations in these genes are identified in human retinal diseases that cause blindness, such as Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP). Herein, we discuss the pathology of 11-cis-retinal deficiency caused by these mutations in both animal disease models and human patients. We also review novel therapeutic strategies employing artificial visual chromophore 9-cis-retinoids which have been employed in clinical trials involving LCA patients.
Keywords: vitamin A; all-trans-retinol; 11-cis-retinal; retina; visual cycle; carotenoids; 9-cis-retinyl acetate; retinal pigmented epithelium; photoreceptor; Leber congenital amaurosis
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Cite This Article
MDPI and ACS Style
Perusek, L.; Maeda, T. Vitamin A Derivatives as Treatment Options for Retinal Degenerative Diseases. Nutrients 2013, 5, 2646-2666.
Perusek L, Maeda T. Vitamin A Derivatives as Treatment Options for Retinal Degenerative Diseases. Nutrients. 2013; 5(7):2646-2666.
Perusek, Lindsay; Maeda, Tadao. 2013. "Vitamin A Derivatives as Treatment Options for Retinal Degenerative Diseases." Nutrients 5, no. 7: 2646-2666.