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Subfunctionalization of a Retinoid-Binding Protein Provides Evidence for Two Parallel Visual Cycles in the Cone-Dominant Zebrafish Retina
- Publication Year :
- 2008
- Publisher :
- Society for Neuroscience, 2008.
-
Abstract
- In vertebrates, the absorption of a photon results in an 11-cisto all-transisomerization of the retinylidene chromophore of cone and rod visual pigments. To sustain vision, metabolic pathways (visual cycles) have evolved that recycle all-trans-retinal back to 11-cis-retinal. The canonical visual cycle takes place in photoreceptor cells and the adjacent retinal pigment epithelium (RPE). Biochemical analyses provided evidence for the existence of an additional cone-specific visual cycle involving Müller glia cells, but none of its molecular components has yet been identified. Here we took advantage of the zebrafish retina to investigate the role of the cellular retinaldehyde-binding protein CRALBP in this process. We found that the zebrafish genome encodes twocralbpparalogs:cralbp aandcralbp b. These paralogs are differentially expressed in the retina. Cralbp a is exclusively expressed in the RPE, and Cralbp b is localized to Müller cells. We used an antisense morpholino approach to knock down eachcralbpparalog. Analysis of 11-cis-retinal levels revealed that visual chromophore regeneration is diminished under both conditions. Visual performance, as assessed by electroretinography, revealed reduced light sensitivity in both Cralbp a- and Cralbp b-deficient larvae, but it was more pronounced in Cralbp b-deficient larvae. Cralbp b-deficient larvae also exhibited significant deficits in their visual behavior. Together, these data demonstrate that Cralbp expression in Müller cells is essential for cone vision, thereby providing evidence that both the canonical and the alternative visual cycle depend on the same type of retinoid-binding protein.
- Subjects :
- animal structures
genetic structures
Retinal Cone Photoreceptor Cells
Retina
medicine
Animals
Protein Isoforms
Pigment Epithelium of Eye
Zebrafish
Vision, Ocular
Retinal pigment epithelium
biology
medicine.diagnostic_test
General Neuroscience
Retinoid binding protein
Anatomy
Articles
Zebrafish Proteins
biology.organism_classification
eye diseases
Cell biology
Retinol-Binding Proteins
medicine.anatomical_structure
Visual Perception
sense organs
Carrier Proteins
Muller glia
Neuroglia
Visual phototransduction
Electroretinography
Photoreceptor Cells, Vertebrate
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....67001d7ccc5266436c2a475a1bb9d597