PURPOSE: Phototransduction in cones is initiated by the bleaching of their visual pigment, which comprises a protein component-cone opsin-and a vitamin A derivative-11-cis retinal. Little is known about the source of 11-cis retinal for cones. In the current study, neural retina leucine zipper-deficient (Nrl(-/-)) and rod opsin (Rho(-/-))-deficient mice were used, two mouse models that have been described as having a "cone-only" retina, to analyze the retinoid metabolism of cones. In addition, these mice were bred to retinal pigment epithelial protein 65 (Rpe65(-/-))-deficient mice to study the role of RPE65. METHODS: Mice were analyzed using morphology, Western blot analysis, immunohistochemistry, electroretinography (ERG), and retinoid profiling by HPLC. RESULTS: In comparison to wild-type mice, the retina of Nrl(-/-) mice contained elevated levels of RPE65 and cellular retinaldehyde-binding protein (CRALBP), suggesting a particular role of these two proteins for the retinoid metabolism of cones. In Nrl(-/-) mice, different retinoid species were present in proportions similar to wild type. Ablation of RPE65 in Nrl(-/-) and Rho(-/-) mice led to the absence of 11-cis retinal, but increased the total retinoid content, with retinyl esters representing the most abundant retinoid species. In the absence of RPE65, retinal sensitivity in Nrl(-/-) mice dropped by a factor of a thousand. CONCLUSIONS: The data show that RPE65, previously shown to be essential for rod function, is also indispensable for the production of 11-cis retinal for cones and thus for cone function.
PURPOSE: Phototransduction in cones is initiated by the bleaching of their visual pigment, which comprises a protein component-cone opsin-and a vitamin A derivative-11-cis retinal. Little is known about the source of 11-cis retinal for cones. In the current study, neural retina leucine zipper-deficient (Nrl(-/-)) and rod opsin (Rho(-/-))-deficient mice were used, two mouse models that have been described as having a "cone-only" retina, to analyze the retinoid metabolism of cones. In addition, these mice were bred to retinal pigment epithelial protein 65 (Rpe65(-/-))-deficient mice to study the role of RPE65. METHODS:Mice were analyzed using morphology, Western blot analysis, immunohistochemistry, electroretinography (ERG), and retinoid profiling by HPLC. RESULTS: In comparison to wild-type mice, the retina of Nrl(-/-) mice contained elevated levels of RPE65 and cellular retinaldehyde-binding protein (CRALBP), suggesting a particular role of these two proteins for the retinoid metabolism of cones. In Nrl(-/-) mice, different retinoid species were present in proportions similar to wild type. Ablation of RPE65 in Nrl(-/-) and Rho(-/-) mice led to the absence of 11-cis retinal, but increased the total retinoid content, with retinyl esters representing the most abundant retinoid species. In the absence of RPE65, retinal sensitivity in Nrl(-/-) mice dropped by a factor of a thousand. CONCLUSIONS: The data show that RPE65, previously shown to be essential for rod function, is also indispensable for the production of 11-cis retinal for cones and thus for cone function.
Authors: Fan Yang; Hongwei Ma; Joshua Belcher; Michael R Butler; T Michael Redmond; Sanford L Boye; William W Hauswirth; Xi-Qin Ding Journal: FASEB J Date: 2016-09-13 Impact factor: 5.191
Authors: M Dominik Fischer; Gesine Huber; Susanne C Beck; Naoyuki Tanimoto; Regine Muehlfriedel; Edda Fahl; Christian Grimm; Andreas Wenzel; Charlotte E Remé; Serge A van de Pavert; Jan Wijnholds; Marek Pacal; Rod Bremner; Mathias W Seeliger Journal: PLoS One Date: 2009-10-19 Impact factor: 3.240