Regeneration of 11-cis-Retinal in the Retinoid Visual Cycle

2011 ◽  
pp. 48-69
Keyword(s):  
Visual Cycle

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.

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.

scholarly journals Pathophysiological features of the visual cycle, cascade and metabolic pathways in retinitis pigmentosa

2021 ◽  
Vol 14 (1) ◽  
pp. 80-88
Author(s):  
M. E. Weener ◽  
D. S. Atarshchikov ◽  
V. V. Kadyshev ◽  
I. V. Zolnikova ◽  
A. M. Demchinsky ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Literature Review ◽  
Retinitis Pigmentosa ◽  
Metabolic Pathways ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Visual Signal ◽  
Visual Cycle ◽  
Target Treatment ◽  
Interphotoreceptor Matrix

This literature review offers a detailed description of the genes and proteins involved in pathophysiological processes in isolated retinitis pigmentosa (RP). To date, 84 genes and 7 candidate genes have been described for non-syndromic RP. Each of these genes encodes a protein that plays a role in vital processes in the retina and / or retinal pigment epithelium, including the cascade of phototransduction (transmission of the visual signal), the visual cycle, ciliary transport, the environment of photoreceptor cilia and the interphotoreceptor matrix. The identification and study of pathophysiological pathways affected in non-syndromic RP is important for understanding the main pathogenic ways and developing approaches to target treatment.

17 Isomerizations in the Visual Cycle

The Enzymes ◽  
1972 ◽  
pp. 573-590 ◽  
Author(s):  
Joram Heller
Keyword(s):  
Visual Cycle

scholarly journals Retinal degeneration associated with RDH12 mutations results from decreased 11-cis retinal synthesis due to disruption of the visual cycle

2006 ◽  
Vol 15 (9) ◽  
pp. 1559-1559
Author(s):  
Debra A. Thompson ◽  
Andreas R. Janecke ◽  
Jessica Lange ◽  
Kecia L. Feathers ◽  
Christian A. Hübner ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Visual Cycle

scholarly journals The role of retinal photoisomerase in the visual cycle of the honeybee.

1991 ◽  
Vol 97 (1) ◽  
pp. 143-165 ◽  
Author(s):  
W C Smith ◽  
T H Goldsmith
Keyword(s):  
Visual Pigment ◽  
Compound Eye ◽  
Rod Outer Segments ◽  
Visual Cycle ◽  
In Vitro Techniques ◽  
The Third ◽  
Isomerization Processes

The compound eye of the honeybee has previously been shown to contain a soluble retinal photoisomerase which, in vitro, is able to catalyze stereospecifically the photoconversion of all-trans retinal to 11-cis retinal. In this study we combine in vivo and in vitro techniques to demonstrate how the retinal photoisomerase is involved in the visual cycle, creating 11-cis retinal for the generation of visual pigment. Honeybees have approximately 2.5 pmol/eye of retinal associated with visual pigments, but larger amounts (4-12 pmol/eye) of both retinal and retinol bound to soluble proteins. When bees are dark adapted for 24 h or longer, greater than 80% of the endogenous retinal, mostly in the all-trans configuration, is associated with the retinal photoisomerase. On exposure to blue light the retinal is isomerized to 11-cis, which makes it available to an alcohol dehydrogenase. Most of it is then reduced to 11-cis retinol. The retinol is not esterified and remains associated with a soluble protein, serving as a reservoir of 11-cis retinoid available for renewal of visual pigment. Alternatively, 11-cis retinal can be transferred directly to opsin to regenerate rhodopsin, as shown by synthesis of rhodopsin in bleached frog rod outer segments. This retinaldehyde cycle from the honeybee is the third to be described. It appears very similar to the system in another group of arthropods, flies, and differs from the isomerization processes in vertebrates and cephalopod mollusks.

Sign in / Sign up

Export Citation Format

Share Document