scholarly journals cisRetinol oxidation regulates photoreceptor access to the retina visual cycle and cone pigment regeneration

2016 ◽  
Vol 594 (22) ◽  
pp. 6753-6765 ◽  
Author(s):  
Shinya Sato ◽  
Vladimir J. Kefalov
Keyword(s):  
Visual Cycle ◽  
Cone Pigment

scholarly journals Function of mammalian M-cones depends on the level of CRALBP in Müller cells

2020 ◽  
Vol 153 (1) ◽  
Author(s):  
Alexander V. Kolesnikov ◽  
Philip D. Kiser ◽  
Krzysztof Palczewski ◽  
Vladimir J. Kefalov
Keyword(s):  
Dark Adaptation ◽  
Molecular Mechanisms ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Müller Cells ◽  
Muller Cells ◽  
Visual Cycle ◽  
Gene Encoding ◽  
Rods And Cones ◽  
Cone Pigment

Cone photoreceptors mediate daytime vision in vertebrates. The rapid and efficient regeneration of their visual pigments following photoactivation is critical for the cones to remain photoresponsive in bright and rapidly changing light conditions. Cone pigment regeneration depends on the recycling of visual chromophore, which takes place via the canonical visual cycle in the retinal pigment epithelium (RPE) and the Müller cell–driven intraretinal visual cycle. The molecular mechanisms that enable the neural retina to regenerate visual chromophore for cones have not been fully elucidated. However, one known component of the two visual cycles is the cellular retinaldehyde-binding protein (CRALBP), which is expressed both in the RPE and in Müller cells. To understand the significance of CRALBP in cone pigment regeneration, we examined the function of cones in mice heterozygous for Rlbp1, the gene encoding CRALBP. We found that CRALBP expression was reduced by ∼50% in both the RPE and retina of Rlbp1+/− mice. Electroretinography (ERG) showed that the dark adaptation of rods and cones is unaltered in Rlbp1+/− mice, indicating a normal RPE visual cycle. However, pharmacologic blockade of the RPE visual cycle revealed suppressed cone dark adaptation in Rlbp1+/− mice in comparison with controls. We conclude that the expression level of CRALPB specifically in the Müller cells modulates the efficiency of the retina visual cycle. Finally, blocking the RPE visual cycle also suppressed further cone dark adaptation in Rlbp1−/− mice, revealing a shunt in the classical RPE visual cycle that bypasses CRALBP and allows partial but unexpectedly rapid cone dark adaptation.

Retinol dehydrogenases: Membrane-bound enzymes for the visual function

2014 ◽  
Vol 92 (6) ◽  
pp. 510-523 ◽  
Author(s):  
Mustapha Lhor ◽  
Christian Salesse
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Membrane Binding ◽  
Large Family ◽  
Structural Features ◽  
Visual Cycle ◽  
Retinoid Metabolism ◽  
Current State ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

Retinoid metabolism is important for many physiological functions, such as differenciation, growth, and vision. In the visual context, after the absorption of light in rod photoreceptors by the visual pigment rhodopsin, 11-cis retinal is isomerized to all-trans retinal. This retinoid subsequently undergoes a series of modifications during the visual cycle through a cascade of reactions occurring in photoreceptors and in the retinal pigment epithelium. Retinol dehydrogenases (RDHs) are enzymes responsible for crucial steps of this visual cycle. They belong to a large family of proteins designated as short-chain dehydrogenases/reductases. The structure of these RDHs has been predicted using modern bioinformatics tools, which allowed to propose models with similar structures including a common Rossman fold. These enzymes undergo oxidoreduction reactions, whose direction is dictated by the preference and concentration of their individual cofactor (NAD(H)/NADP(H)). This review presents the current state of knowledge on functional and structural features of RDHs involved in the visual cycle as well as knockout models. RDHs are described as integral or peripheral enzymes. A topology model of the membrane binding of these RDHs via their N- and (or) C-terminal domain has been proposed on the basis of their individual properties. Membrane binding is a crucial issue for these enzymes because of the high hydrophobicity of their retinoid substrates.

Spectral Tuning in the Human Blue Cone Pigment†

Biochemistry ◽  
1999 ◽  
Vol 38 (36) ◽  
pp. 11593-11596 ◽  
Author(s):  
Jeffry I. Fasick ◽  
Ning Lee ◽  
Daniel D. Oprian
Keyword(s):  
Spectral Tuning ◽  
Cone Pigment

scholarly journals Quantal noise from human red cone pigment

2008 ◽  
Vol 11 (5) ◽  
pp. 565-571 ◽  
Author(s):  
Yingbin Fu ◽  
Vladimir Kefalov ◽  
Dong-Gen Luo ◽  
Tian Xue ◽  
King-Wai Yau
Keyword(s):  
Cone Pigment

Divergent Phenotypes of Vision and Accessory Visual Function in Mice with Visual Cycle Dysfunction (Rpe65rd12) or Retinal Degeneration (rd/rd)

2008 ◽  
Vol 49 (6) ◽  
pp. 2737 ◽  
Author(s):  
Stewart Thompson ◽  
Robert F. Mullins ◽  
Alisdair R. Philp ◽  
Edwin M. Stone ◽  
N. Mrosovsky
Keyword(s):  
Retinal Degeneration ◽  
Visual Function ◽  
Visual Cycle

scholarly journals The rhodopsin-retinochrome system for retinal re-isomerization predates the origin of cephalopod eyes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Oliver Vöcking ◽  
Lucas Leclère ◽  
Harald Hausen
Keyword(s):  
In Situ Hybridization ◽  
Photoreceptor Cells ◽  
Visual Cycle ◽  
Phylogenetic Distribution ◽  
Enzymatic Process ◽  
Antibody Staining ◽  
The Individual ◽  
Functional Components ◽  
Visual Rhodopsin

Abstract Background The process of photoreception in most animals depends on the light induced isomerization of the chromophore retinal, bound to rhodopsin. To re-use retinal, the all-trans-retinal form needs to be re-isomerized to 11-cis-retinal, which can be achieved in different ways. In vertebrates, this mostly includes a stepwise enzymatic process called the visual cycle. The best studied re-isomerization system in protostomes is the rhodopsin-retinochrome system of cephalopods, which consists of rhodopsin, the photoisomerase retinochrome and the protein RALBP functioning as shuttle for retinal. In this study we investigate the expression of the rhodopsin-retinochrome system and functional components of the vertebrate visual cycle in a polyplacophoran mollusk, Leptochiton asellus, and examine the phylogenetic distribution of the individual components in other protostome animals. Results Tree-based orthology assignments revealed that orthologs of the cephalopod retinochrome and RALBP are present in mollusks outside of cephalopods. By mining our dataset for vertebrate visual cycle components, we also found orthologs of the retinoid binding protein RLBP1, in polyplacophoran mollusks, cephalopods and a phoronid. In situ hybridization and antibody staining revealed that L. asellus retinochrome is co-expressed in the larval chiton photoreceptor cells (PRCs) with the visual rhodopsin, RALBP and RLBP1. In addition, multiple retinal dehydrogenases are expressed in the PRCs, which might also contribute to the rhodopsin-retinochrome system. Conclusions We conclude that the rhodopsin-retinochrome system is a common feature of mollusk PRCs and predates the origin of cephalopod eyes. Our results show that this system has to be extended by adding further components, which surprisingly, are shared with vertebrates.

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