The visual process is initiated by the photoisomerization of 11-cis-retinal to all-trans-retinal. For sustained vision the 11-cis-chromophore must be regenerated from all-trans-retinal. This requires RPE65, a dominant retinal pigment epithelium protein. Disruption of the RPE65 gene results in massive accumulation of alltrans-retinyl esters in the retinal pigment epithelium, lack of 11-cis-retinal and therefore rhodopsin, and ultimately blindness. We reported previously (Van Hooser, J. P., Aleman, T. S., He, Y. G., Cideciyan, A. V., Kuksa, V., Pittler, S. J., Stone, E. M., Jacobson, S. G., and Palczewski, K. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8623-8628) that in Rpe65؊/؊ mice, oral administration of 9-cis-retinal generated isorhodopsin, a rod photopigment, and restored light sensitivity to the electroretinogram. Here, we provide evidence that early intervention by 9-cis-retinal administration significantly attenuated retinal ester accumulation and supported rod retinal function for more than 6 months post-treatment. In single cell recordings rod light sensitivity was shown to be a function of the amount of regenerated isorhodopsin; high doses restored rod responses with normal sensitivity and kinetics. Highly attenuated residual rod function was observed in untreated Rpe65؊/؊ mice. This rod function is likely a consequence of low efficiency production of 11-cis-retinal by photo-conversion of alltrans-retinal in the retina as demonstrated by retinoid analysis. These studies show that pharmacological intervention produces long lasting preservation of visual function in dark-reared Rpe65؊/؊ mice and may be a useful therapeutic strategy in recovering vision in humans diagnosed with Leber congenital amaurosis caused by mutations in the RPE65 gene, an inherited group of early onset blinding and retinal degenerations. Leber congenital amaurosis (LCA)1 is a group of conditions that cause blindness or severe visual impairment from birth. All show both rod and cone dysfunction, a negligible (not recordable) electroretinogram (ERG), and nystagmus. They result in early onset retinal dystrophy (1), which over time may be accompanied by pigmentary changes in the retina, hence "amaurosis" (Greek for darken). LCA is caused by defects in at least five different genes that disrupt a variety of different cellular functions (2-6).In ϳ12% of all LCA cases the gene for a 65-kDa protein (RPE65) of retinal pigment epithelium cells (RPE) is disabled (7,8). RPE65 is heavily expressed in RPE cells, where it plays an essential role in the retinoid cycle. This is a set of tightly interconnected events that involve both photoreceptors and RPE cells. The photoisomerization of the visual pigment chromophore (11-cis-retinal) produces all-trans-retinal, which is reduced in the photoreceptor, transferred to the RPE, converted back to 11-cis-retinal, and then transferred back to the photoreceptor to regenerate the original visual pigment (reviewed in Ref. 9). The precise function of RPE65 in retinoid processing is unknown.Genetically enginee...

Oxidation of docosahexaenoate phospholipids produces 4-hydroxy-7-oxo-hept-5-eonyl phospholipids (HOHA-PLs) that react with protein lysyl ε-amino residues to generate 2-ω-carboxyethylpyrrole (CEP) derivatives, endogenous factors that induce angiogenesis in the retina and tumors. It seemed likely, but remained unproven, that HOHA-PLs react with ethanolamine phospholipids (EPs) in vivo to generate CEP-EPs. We now show that CEP-EPs are present in human blood at 4.6-fold higher levels in age-related macular degeneration plasma than in normal plasma. We also show that CEP-EPs are pro-angiogenic, inducing tube formation by human umbilical vein endothelial cells by activating Toll-like receptor 2. CEP-EP levels may be a useful biomarker for clinical assessment of AMD risk and CEP-associated tumor progression and a tool for monitoring the efficacy of therapeutic interventions.

Phototransduction is initiated by the photoisomerization of rhodopsin (Rho) chromophore 11-cis-retinylidene to all-trans-retinylidene. Here, using Rho regenerated with retinal analogs with different ring sizes, which prevent isomerization around the C 11 ‫؍‬C 12 double bond, the activation mechanism of this G-protein-coupled receptor was investigated. We demonstrate that 11-cis-7-ring-Rho does not activate G-protein in vivo and in vitro, and that it does not isomerize along other double bonds, suggesting that it fits tightly into the binding site of opsin. In contrast, bleaching 11-cis-6-ring-Rho modestly activates phototransduction in vivo and at low pH in vitro. These results reveal that partial activation is caused by isomerization along other double bonds in more rigid 6-locked retinal isomers and protonation of key residues by lowering pH in 11-cis-6-ring-Rhos. Full activation is not achieved, because isomerization does not induce a complete set of conformational rearrangements of Rho. These results with 6-and 7-ringconstrained retinoids provide new insights into Rho activation and suggest a potential use of locked retinals, particularly 11-cis-7-ring-retinal, to inactivate opsin in some retinal degeneration diseases.In vertebrate retinal photoreceptor cells, isomerization of the visual pigment chromophore, 11-cis-retinal to all-trans-retinal, triggers a set of reactions collectively termed the phototransduction cascade (1, 2). The phototransduction events are initiated by activated rhodopsin (Rho*) 1 and progress through a classical G-protein cascade, ultimately leading to neuronal signaling. Metarhodopsin II (or Meta II, Rho*), the catalytically active intermediate generated by photoisomerization of Rho chromophore, contains all-trans-retinal covalently bound to Lys 296 of opsin via the deprotonated Schiff base. Subsequently, Meta II undergoes reprotonation, and the photolyzed chromophore is hydrolyzed and released from opsin (3-5). The precise mechanism of Rho activation by the photoisomerized chromophore is unknown (6).The photobleaching process of rhodopsin has been investigated using retinal analogs that contained an extra ring between C 10 and C 13 , making retinal non-isomerizable around the 11-cis double bond (7-12). An artificial visual pigment with restricted C 9 -C 11 motion forms normal photolysis intermediates (13), suggesting an importance of C 11 ϭC 12 bond isomerization in the activation of Rho. More recently, it was reported that after photoisomerization, the ␤-ionone ring of the chromophore moves to a new position during the transition to Meta II (7). Jang et al. (14) showed using 6-ring-constrained retinal isomers and the crystal structure of Rho in the ground state (15) that if this movement is restricted, only residual activity could be observed. Locked retinal analogs were also used to study visual transduction in vivo using vitamin A-deprived rats (16, 17). These animals had approximately half of the normal complement of rhodopsin, and injection of locked retinal led to the appearan...

Myofibroblasts are fibroblastic cells that function in wound healing, tissue repair and fibrosis, and arise from bone marrow (BM)-derived fibrocytes and a variety of local progenitor cells. In the cornea, myofibroblasts are derived primarily from stromal keratocytes and from BM-derived fibrocytes after epithelial-stromal and endothelial-stromal injuries. Quantitative proteomic comparison of mature alpha-smooth muscle actin (α-SMA)+ myofibroblasts (verified by immunocytochemistry for vimentin, α-SMA, desmin, and vinculin) generated from rabbit corneal fibroblasts treated with transforming growth factor (TGF) beta-1 or generated directly from cultured BM treated with TGF beta-1 was pursued for insights into possible functional differences. Paired cornea-derived and BM-derived α-SMA+ myofibroblast primary cultures were generated from four New Zealand white rabbits and confirmed to be myofibroblasts by immunocytochemistry. Paired cornea- and BM-derived myofibroblast specimens from each rabbit were analyzed by LC MS/MS iTRAQ technology using an Orbitrap Fusion Lumos Tribrid mass spectrometer, the Mascot search engine, the weighted average quantification method and the UniProt rabbit and human databases. From 2329 proteins quantified with ≥ 2 unique peptides from ≥ 3 rabbits, a total of 673 differentially expressed (DE) proteins were identified. Bioinformatic analysis of DE proteins with Ingenuity Pathway Analysis implicate progenitor-dependent functional differences in myofibroblasts that could impact tissue development. Our results suggest BM-derived myofibroblasts may be more prone to the formation of excessive cellular and extracellular material that are characteristic of fibrosis.