Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Changes in the steady state level of retinols, retinaldehydes and retinyl esters in the trans and 11-cis forms and trans retinoic acid were measured in whole chicken eye during development from day 6 in ovo to day 3 post-hatch. These retinoids, quantified by different HPLC systems, were detected in this time sequence: trans-retinol and trans-retinyl esters in the first week in ovo, 11-cis-retinol in the second week. The highest level of 11-cis-retinaldehyde and 11-cis-retinyl esters was reached at the end of development in ovo; however, their levels increased further after hatching. The retinoic acid level decreased at the end of the first week, rising again at the end of the second week. The enzyme activities involved in the metabolism of these retinoids-acyl-CoA: retinol acyltransferase, trans-retinol dehydrogenase, 11-cis-retinol dehydrogenase, trans-retinyl ester hydrolase and trans: 11-cis-retinol isomerase were also estimated and they were detectable already in the first week of development in ovo. At day 6 of the biosynthesis of retinoic acid by the retinaldehyde dehydrogenase activity from retina cytosol was also shown.
Mol Cell Biochem 1994 Mar 16
PMID:Retinoid dynamics in chicken eye during pre- and postnatal development. 807 8

The visual cycle, the biochemical process by which the light-sensitive isomer of vitamin A is continually recycled, is crucial to vision in a healthy eye. More than 150 years of research into this remarkable biochemical process has given invaluable understanding in debilitating visual diseases that impact thousands of individuals worldwide, many of them children. The visual cycle spans photoreceptor cells in the retina and the underlying retinal pigment epithelium (RPE) and requires a protein called RPE65 for its function. In many ways, RPE65 is the capstone to the cyclical processing of vitamin A in the eye, and the discovery of this retinol isomerase helped fill a critical gap in the understanding of retinoid processing in vision. This chapter will focus on the history of visual cycle research, from the first experiments well over a century ago to the discovery of RPE65. Because of the undeniable importance of RPE65 in the visual cycle, this chapter will also focus on the protein structure and mechanism by which it converts light-insensitive all-trans-vitamin A to light-sensitive 11-cis-vitamin A for continued visual function. Finally, this chapter will briefly discuss RPE65 and its known disease associations in the clinical setting. Thanks to the efforts of researchers for well over a century in studying the visual cycle, the medical community is now poised to make significant gains in the treatment of blindness.
Prog Mol Biol Transl Sci 2015
PMID:A History of the Classical Visual Cycle. 2631 Jan 69

Astyanax mexicanus consists of two forms, a sighted surface dwelling form (surface fish) and a blind cave-dwelling form (cavefish). Embryonic eyes are initially formed in cavefish but they are subsequently arrested in growth and degenerate during larval development. Previous lens transplantation studies have shown that the lens plays a central role in cavefish eye loss. However, several lines of evidence suggest that additional factors, such as the retinal pigment epithelium (RPE), which is morphologically altered in cavefish, could also be involved in the eye regression process. To explore the role of the RPE in cavefish eye degeneration, we generated an albino eyed (AE) strain by artificial selection for hybrid individuals with large eyes and a depigmented RPE. The AE strain exhibited an RPE lacking pigment granules and showed reduced expression of the RPE specific enzyme retinol isomerase, allowing eye development to be studied by lens ablation in an RPE background resembling cavefish. We found that lens ablation in the AE strain had stronger negative effects on eye growth than in surface fish, suggesting that an intact RPE is required for normal eye development. We also found that the AE strain develops a cartilaginous sclera lacking boney ossicles, a trait similar to cavefish. Extrapolation of the results to cavefish suggests that the RPE and lens have dual roles in eye degeneration, and that deficiencies in the RPE may be associated with evolutionary changes in scleral ossification.
J Exp Zool B Mol Dev Evol 2020 Nov
PMID:Dual roles of the retinal pigment epithelium and lens in cavefish eye degeneration. 3193 Jun 86