Pigment epithelium

Disorder characterized by atrophy ofthe choroid (the thin membrane covering most of the posterior of the eye between the retina and sclera) and degeneration of the retinal pigment epithelium resulting in night blindness. The disease is caused by mutations in Rab escort protein Repl (component A of Rab geranylgeranyl transferase). 

LUTTY G, GRUNWALD J, MAjji A B, UYAMA M and YONEYA s (1999) Changes in choriocapillaris and retinal pigment epithelium (RPE) in age-related macular degeneration. Mol Vis. 5 35-8. 

Melanins are prodnced in mammals in two types of cells of different developmental origin (1) the melanocytes of the skin, hair, choroids and iris and (2) the retinal pigment epithelium (RPE). Specialized organelles of the melanocytes, the melano-somes, synthesize and store eumelanins and phaeomelanins. 

Seagle, B.L. et al., Melanin photoprotection in the human retinal pigment epithelium and its correlation with light-induced cell apoptosis, Proc. Natl. Acad. Sci. USA, 102, 8978, 2005. 

The retina comprises two principal components, the non-neural retinal pigment epithelium and the neural retina. The retinal pigment epithelium is an essential component of the visual system both structurally and functionally. It is important for the turnover and phagocytosis of photoreceptor outer segments, the metabolism of retinoids, the exchange of nutrients between the photoreceptors, and the choroidal blood vessels and the maintenance of an efficient outer blood-retinal barrier. 

Figure 7. Expression pattern of the mouse tyrosinase gene during embryonic development and its recapitulation in transgenic mice as determined by in situ hybridization (Beermann et al., 1992a). Black box, mouse tyrosinase open box, transgene ptrTyrf striped box, ptrTyr5. Interrupted boxes indicate variations between lines. RPE, retinal pigment epithelium e, days of gestation d0.5, newborn.

Kltippel, M Beermann.F., Ruppert, S., Schmid, E Hummler, E., and Schiitz, G. (1991). The mouse tyrosinase promoter is sufficient for expression in melanocytes and in the pigmented epithelium of the retina. Proc. Natl. Acad. Sci. USA 88 3777-3781. 

Bleaching is reversed in the dark and the red-purple color of rhodopsin returns. This is thought to occur by the reduction of all-Pms-retinal to vitamin Ai (retinal), which diffuses from the rod into the pigment epithelium, where it is converted enzymatically to the 1 l-c isomer of vitamin At. The enzymatic isomerization is followed by diffusion back into the rod, oxidation to 11 -rfr-retinal, and combination with opsin to form rhodopsin. This process is shown schematically in Figure 12.5.[Pg.289]

Parish, C. A. et al. (1998). Isolation and one-step preparation of A2E and iso-A2E, fluorophores from human retinal pigment epithelium. Proceedings of the National Academy of Sciences 95 2988-2995. 

Lutein and zeaxanthin are the dominant carotenoids in nonretinal eye tissue, and lycopene and p-carotene have been found in the ciliary body, which after the retina and the retinal pigment epithelium (RPE) contains the highest quantity of carotenoids (Bernstein et al. 2001). The orbital adipose tissue also contains measurable quantities of lutein and p-carotene, and possibly other carotenoids as minor constituents (Sires et al. 2001). It is also interesting to note that lutein was recently identified in the vitreous body of human fetuses, 15-28 weeks old (Yakovleva et al. 2007). However, these results may have to be considered with caution, because the vitreous bodies were described as substantially being penetrated with hyaloid blood vessels, which could have contaminated the vitreous with blood. 

Leung, I. Y., M. M. Sandstrom et al. (2004). Nutritional manipulation of primate retinas, II Effects of age, n-3 fatty acids, lutein, and zeaxanthin on retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 45(9) 3244-3256. 

Anderson, DH, Ozaki, S, Nealon, M, Neitz, J, Mullins, RF, Hageman, GS, and Johnson, LV, 2001. Local cellular sources of apolipoprotein E in the human retina and retinal pigmented epithelium implications for the process of drusen formation. Am J Ophthalmol 131, 767-781. 

Bailey, KR, Ishida, BY, Duncan, KG, Kane, JP, and Schwartz, DM, 2004. Basal reverse cholesterol transport of retinal pigment epithelium cell digested photoreceptor outer segment lipids. Invest Ophthalmol Vis Sci 45, U721. 

Constable, PA, Lawrenson, JG, Dolman, DE, Arden, GB, and Abbott, NJ, 2006. P-Glycoprotein expression in human retinal pigment epithelium cell lines. Exp Eye Res 83, 24—30. 

Hahn, P, Milam, AH, and Dunaief, JL, 2003. Maculas affected by age-related macular degeneration contain increased chelatable iron in the retinal pigment epithelium and Bruch s membrane. Arch Ophthalmol 121, 1099-1105. 

Holtkamp, GM, Kijlstra, A, Peek, R, and de Vos, AF, 2001. Retinal pigment epithelium-immune system interactions Cytokine production and cytokine-induced changes. Prog Retin Eye Res 20, 29-48. 

Kennedy, BG and Mangini, NJ, 2002. P-glycoprotein expression in human retinal pigment epithelium. Mol Vis 8, 422-430. 

Confluent monolayers of cultured human fetal retinal pigment epithelium exhibit morphology and physiology of native tissue. Invest Ophthalmol Vis Sci 47, 3612-3624. 

Marin-Castano, ME, Striker, GE, Alcazar, O, Catanuto, P, Espinosa-Heidmann, DG, and Cousins, SW, 2006. Repetitive nonlethal oxidant injury to retinal pigment epithelium decreased extracellular matrix turnover in vitro and induced sub-RPE deposits in vivo. Invest Ophthalmol Vis Sci 47,4098-4112. 

Ryeom, SW, Silverstein, RL, Scotto, A, and Sparrow, JR, 1996a. Binding of anionic phospholipids to retinal pigment epithelium may be mediated by the scavenger receptor CD36. J Biol Chem 271, 20536-20539. 

Ryeom, SW, Sparrow, JR, and Silverstein, RL, 1996b. CD36 participates in the phagocytosis of rod outer segments by retinal pigment epithelium. J Cell Sci 109, 387-395. 

Strauss, O, 2005. The retinal pigment epithelium in visual function. Physiol Rev 85, 845-881. 

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