Disease relevance of retinal

• The product of retinal isomerization is all-E-retinal, which in the eye is a biosynthetic precursor to N-retinylidene-N-retinylethanolamine, a hallmark of age-related macular degeneration [1].
• To restore light sensitivity, the all-trans-retinaldehyde must be chemically re-isomerized by an enzyme pathway called the visual cycle [2].

High impact information on retinal

• Furthermore, 9-Z- and all-E-retinal isomers are biosynthetic precursors to 9-Z- and all-E-retinoic acids, ligands that mediate specific cellular responses by binding to transcriptional regulatory proteins critical in growth and development [1].
• Exposure of human adult RPE cells to UV light at predominantly 320-400 nm (UVA light) in the presence of all-trans-retinaldehyde results in photooxidative cytotoxicity [3].
• Light activation of rhodopsin results in its release of all-trans-retinaldehyde, which constitutes the first reactant in A2E biosynthesis [4].
• Proof that the effects of HNE and trans-retinal are mediated by UCP is provided by examination of proton conductance in transgenic plants overexpressing UCP [5].
• We demonstrate that 4-hydroxy-2-nonenal (HNE), a product of lipid peroxidation, and a structurally related compound, trans-retinal, stimulate a proton conductance in potato mitochondria that is inhibitable by GTP (a characteristic of UCP) [5].

Biological context of retinal

• 11-cis-Retinaldehyde and all-trans-retinol were found to dissociate from the strong binding site of IRBP 3-4-fold slower than all-trans-retinaldehyde and 11-cis-retinol [6].
• The light-evoked trans-tissue potential (TTP), the trans-epithelial potential (TEP), the trans-retinal potentials, and the intracellularly-recorded apical and basal membrane potentials were studied [7].
• This indicates that the rabbit eye is a good model for studying intravitreal pharmacokinetics of ganciclovir and suggests a common elimination mechanism which may be trans-retinal [8].

Anatomical context of retinal

• The effect on the EECP of sequential epi-retinal (i.e. return electrode on epi-retinal surface) vs. trans-retinal (i.e. return electrode behind sclera) stimulation was compared [9].

Gene context of retinal

• Recombinant chick ALDH6 has a K(0.5) = 0.26 microm, V(max) = 48.4 nmol/min/mg and exhibits strong positive cooperativity (H = 1.9) toward all-trans-retinaldehyde; mouse ALDH6 has similar kinetic parameters [10].
• When coexpressed with arrestins, melanopsin could use all-trans-retinaldehyde as a chromophore, which suggests that it may function as a bireactive opsin [11].
• The level of ATPase activity was comparable to that of trans-retinal-stimulated ABCR ATPase [12].
• The action spectrum has a maximum of 500 nm, and the entire spectrum from 350 to 800 nm closely matches the absorption spectrum of rhodopsin, which is apparently the pigment which mediates the effects of light on phosphodiesterase activity. trans-Retinal alone does not mimic light [13].

Analytical, diagnostic and therapeutic context of retinal

• Treatments aimed at avoiding enucleation include: plaque, proton beam or stereotactic radiotherapy; trans-scleral or trans-retinal local resection; and transpupillary thermotherapy [14].

References