tretinoin and Retinal-Degeneration

Rod and cone photoreceptors degenerate in retinitis pigmentosa (RP). While downstream neurons survive, they undergo physiological changes, including accelerated spontaneous firing in retinal ganglion cells (RGCs). Retinoic acid (RA) is the molecular trigger of RGC hyperactivity, but whether this interferes with visual perception is unknown. Here, we show that inhibiting RA synthesis with disulfiram, a deterrent of human alcohol abuse, improves behavioral image detection in vision-impaired mice. In vivo Ca

Topics: Animals; Disease Models, Animal; Mice; Retinal Degeneration; Retinal Ganglion Cells; Retinitis Pigmentosa; Tretinoin

Retinitis Pigmentosa (RP) is a progressive, debilitating visual disorder caused by mutations in a diverse set of genes. In both humans with RP and mouse models of RP, rod photoreceptor dysfunction leads to loss of night vision, and is followed by secondary cone photoreceptor dysfunction and degeneration, leading to loss of daylight color vision. A strategy to prevent secondary cone death could provide a general RP therapy to preserve daylight color vision regardless of the underlying mutation. In mouse models of RP, cones in the peripheral retina survive long-term, despite complete rod loss. The mechanism for such peripheral cone survival had not been explored. Here, we found that active retinoic acid (RA) signaling in peripheral Muller glia is necessary for the abnormally long survival of these peripheral cones. RA depletion by conditional knockout of RA synthesis enzymes, or overexpression of an RA degradation enzyme, abrogated the extended survival of peripheral cones. Conversely, constitutive activation of RA signaling in the central retina promoted long-term cone survival. These results indicate that RA signaling mediates the prolonged peripheral cone survival in the rd1 mouse model of retinal degeneration, and provide a basis for a generic strategy for cone survival in the many diseases that lead to loss of cone-mediated vision.

Topics: Animals; Color Vision; Disease Models, Animal; Mice; Retina; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinitis Pigmentosa; Tretinoin

Light responses are initiated in photoreceptors, processed by interneurons, and synaptically transmitted to retinal ganglion cells (RGCs), which send information to the brain. Retinitis pigmentosa (RP) is a blinding disease caused by photoreceptor degeneration, depriving downstream neurons of light-sensitive input. Photoreceptor degeneration also triggers hyperactive firing of RGCs, obscuring light responses initiated by surviving photoreceptors. Here we show that retinoic acid (RA), signaling through its receptor (RAR), is the trigger for hyperactivity. A genetically encoded reporter shows elevated RAR signaling in degenerated retinas from murine RP models. Enhancing RAR signaling in healthy retinas mimics the pathophysiology of degenerating retinas. Drug inhibition of RAR reduces hyperactivity in degenerating retinas and unmasks light responses in RGCs. Gene therapy inhibition of RAR increases innate and learned light-elicited behaviors in vision-impaired mice. Identification of RAR as the trigger for hyperactivity presents a degeneration-dependent therapeutic target for enhancing low vision in RP and other blinding disorders.

Topics: Animals; Cell Membrane Permeability; Disease Models, Animal; Electroencephalography; Genetic Therapy; HEK293 Cells; Humans; Mice; Patch-Clamp Techniques; Photosensitivity Disorders; Rats; Receptors, Retinoic Acid; Retinal Degeneration; Retinal Ganglion Cells; Retinitis Pigmentosa; Tretinoin; Vision, Ocular

The loss of cone photoreceptors that mediate daylight vision represents a leading cause of blindness, for which cell replacement by transplantation offers a promising treatment strategy. Here, we characterize cone differentiation in retinas derived from mouse embryonic stem cells (mESCs). Similar to in vivo development, a temporal pattern of progenitor marker expression is followed by the differentiation of early thyroid hormone receptor β2-positive precursors and, subsequently, photoreceptors exhibiting cone-specific phototransduction-related proteins. We establish that stage-specific inhibition of the Notch pathway increases cone cell differentiation, while retinoic acid signaling regulates cone maturation, comparable with their actions in vivo. MESC-derived cones can be isolated in large numbers and transplanted into adult mouse eyes, showing capacity to survive and mature in the subretinal space of Aipl1

Topics: Adaptor Proteins, Signal Transducing; Animals; Basic-Leucine Zipper Transcription Factors; Cell Differentiation; Disease Models, Animal; Eye Proteins; Hepatocyte Nuclear Factor 6; Leukemia Inhibitory Factor; Mice; Mice, Knockout; Mouse Embryonic Stem Cells; Oligodendrocyte Transcription Factor 2; Opsins; Orphan Nuclear Receptors; Otx Transcription Factors; Receptors, Notch; Retinal Cone Photoreceptor Cells; Retinal Degeneration; RNA Interference; RNA, Small Interfering; Signal Transduction; Tretinoin

Anomalous neuritogenesis is a hallmark of neurodegenerative disorders, including retinal degenerations, epilepsy, and Alzheimer's disease. The neuritogenesis processes result in a partial reinnervation, new circuitry, and functional changes within the deafferented retina and brain regions. Using the light-induced retinal degeneration (LIRD) mouse model, which provides a unique platform for exploring the mechanisms underlying neuritogenesis, we found that retinoid X receptors (RXRs) control neuritogenesis. LIRD rapidly triggered retinal neuron neuritogenesis and up-regulated several key elements of retinoic acid (RA) signaling, including retinoid X receptors (RXRs). Exogenous RA initiated neuritogenesis in normal adult retinas and primary retinal cultures and exacerbated it in LIRD retinas. However, LIRD-induced neuritogenesis was partly attenuated in retinol dehydrogenase knockout (Rdh12(-/-)) mice and by aldehyde dehydrogenase inhibitors. We further found that LIRD rapidly increased the expression of glutamate receptor 2 and β Ca(2+)/calmodulin-dependent protein kinase II (βCaMKII). Pulldown assays demonstrated interaction between βCaMKII and RXRs, suggesting that CaMKII pathway regulates the activities of RXRs. RXR antagonists completely prevented and RXR agonists were more effective than RA in inducing neuritogenesis. Thus, RXRs are in the final common path and may be therapeutic targets to attenuate retinal remodeling and facilitate global intervention methods in blinding diseases and other neurodegenerative disorders.

Topics: Alcohol Oxidoreductases; Alitretinoin; Animals; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Disease Models, Animal; Mice; Mice, Inbred BALB C; Mice, Mutant Strains; Neurodegenerative Diseases; Primary Cell Culture; Receptors, AMPA; Receptors, Retinoic Acid; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Retinoic Acid Receptor alpha; Retinoic Acid Receptor gamma; Signal Transduction; Tretinoin; Vision, Ocular

RPE65 gene knockout (Rpe65⁻/⁻) mice showed abolished isomerohydrolase activity in the visual cycle and were considered a model for vitamin A deficiency in the retina. The purpose of this study was to compare the retinal phenotypes between vitamin A-deficient (VAD) mice and Rpe65⁻/⁻ mice under normal diet.. The VAD mice were fed with a vitamin A-deprived diet after birth. The age-matched control mice and Rpe65⁻/⁻ mice were maintained under normal diet. The structure of photoreceptor outer segment was compared using electron microscopy. Photoreceptor-specific gene expression was determined using real-time RT-PCR. The isomerohydrolase and lecithin-retinol acyltransferase (LRAT) activities were measured using an in vitro enzymatic activity assay. Endogenous retinoid profiles were analyzed by HPLC in mouse eyecup homogenates.. Compared to wild-type mice under normal diet, scanning and transmission electron microscopy showed that the outer segments of photoreceptors were disorganized in VAD mice and were not disorganized in Rpe65⁻/⁻ mice, although they were shortened in the latter. VAD mice showed more prominent downregulation of middle wavelength cone opsin, whereas Rpe65⁻/⁻ mice displayed more suppressed expression of short wavelength cone opsin. In vitro enzymatic activity assay and Western blot analysis showed that vitamin A deprivation downregulated LRAT expression and activity in the eyecup, but Rpe65⁻/⁻ mice showed unchanged LRAT expression and activity. The depressed LRAT activity in VAD mice was partially rescued by the intraperitoneal injection of retinoic acid.. VAD and Rpe65⁻/⁻ mice are different in cone photoreceptor degeneration, photoreceptor-specific gene regulation, isomerohydrolase activity, endogenous retinoid profile, and LRAT activity.

Topics: Acyltransferases; Animals; Blotting, Western; Carrier Proteins; Cell Count; Chromatography, High Pressure Liquid; cis-trans-Isomerases; Eye Proteins; Gene Expression; Injections, Intraperitoneal; Mice; Mice, Knockout; Microscopy, Electron, Scanning; Opsins; Phenotype; Photoreceptor Cells, Vertebrate; Retinal Degeneration; Retinal Photoreceptor Cell Outer Segment; Retinal Pigment Epithelium; Reverse Transcriptase Polymerase Chain Reaction; Tretinoin; Vitamin A; Vitamin A Deficiency

The purpose of this study is to characterize the co-expression of nestin--a neuroectodermal stem cell and a reactive glial marker-with various mature retinal cell markers in retinal progenitor cells (RPCs) expanded in vitro, followed either by in vitro induction or subretinal transplantation. Rat RPCs derived from embryonic day (E) 17 rat retina were expanded in serum free defined culture, and induced to differentiate by all-trans retinoic acid (RA). Following induction, cells were stained for nestin in combination with retinal neuronal and glial markers. Cultured cells were collected for quantitative RT-PCR gene expression analysis prior to and after induction. In a second series, passage 2 RPCs were transplanted into the subretinal space of S334ter-3 retinal degeneration rats at postnatal day 28. After 1-4 weeks, sections through the transplant were double immunostained for nestin and various retinal specific neuronal markers. The cultured RPCs treated with RA exhibited nestin co-expression with various retinal specific markers, including protein kinase C alpha (PKC), neurofilament 200 (NF200), cellular retinaldehyde binding protein (CRALBP), and rhodopsin. Following RA induction, quantitative RT-PCR analysis demonstrated downregulation of nestin, PAX-6, thy1.1, and PKCalpha, and upregulation of rhodopsin, glial fibrillary acidic protein (GFAP), and CrX. No nestin coexpression was observed with any of the retinal specific neuronal markers in RPC transplants in vivo except for some nestin-immunoreactivity overlapping with GFAP positive cells in the host retina. The role of nestin as a unique neural stem/progenitor cell marker should be reconsidered. Nestin expression during RPC maturation appears to be different in vitro versus in vivo.

Topics: Animals; Cell Differentiation; Cells, Cultured; Down-Regulation; Female; Intermediate Filament Proteins; Male; Microscopy, Phase-Contrast; Nerve Tissue Proteins; Nestin; Rats; Rats, Mutant Strains; Retina; Retinal Degeneration; Reverse Transcriptase Polymerase Chain Reaction; Stem Cell Transplantation; Stem Cells; Tretinoin

To study the prevention of retinoid acid (RA) to the retinal degeneration when being injected into sub retinal space.. 10(-3) mol/L RA and phosphate buffered saline (PBS) were injected into the sub retinal space of 8 retinal degeneration (rd) mice respectively. The eye was analysed under microscopy one month after injection. 12 rd mice sorted as 4 groups were contrast; there were 3 rd mice whose mouse age was 7, 14, 28 days and 3 months respectively in each group.. The cells in inner nucleus layer had proliferated very much in part of tested eyes at one month. There were no difference between group RA and group PBS.. The degeneration of retina couldn't be stopped and the degenerated retina couldn't be restored to normal through the injection RA into the sub retinal space of rd mouse.

Topics: Administration, Topical; Animals; Mice; Mice, Inbred C3H; Retina; Retinal Degeneration; Tretinoin

Several reports have characterized the retinal degeneration observed in the Mitf(vit) mutant mouse. Despite these reports, the factor(s) that may cause or modulate the degeneration still are not well defined; however, it is known that the photoreceptors of Mitf(vit) mice die through an apoptotic mechanism. We reported previously that retinoid metabolism in the RPE of Mitf(vit)++ mice is perturbed. Retinoids regulate genes via the RAR and RXR nuclear receptor pathway that are involved in numerous cellular responses including apoptosis. It is possible that retinoic acid (RA) modulates the retinal degeneration observed in the Mitf(vit) mice. The purpose of this study was to evaluate the levels of RA in whole eyes, as well as its distribution between neural retina and RPE, of the Mitf(vit) mutant mouse model. An additional purpose was to examine the expression of the RA generating enzyme, retinaldehyde dehydrogenase (AHD2), in the eyes of mutant and control mice.. The distribution of AHD2 in eyes of pre- and postnatal Mitf(vit) and C57BL/6 wild-type mice was determined immunohistochemically. Quantitative and qualitative analyses of RA were performed using reversed-phase high performance liquid chromatography (HPLC).. The distribution of AHD2 in ocular tissues was similar between pre- and postnatal Mitf(vit) and C57BL/6 control mice. At postnatal week 10, however, a marked increase in AHD2 immunoreactivity was noted in the central dorsal neural retina of Mitf(vit) mice. No differences in the level of total RA in whole eyes were noted between Mitf(vit) and control mice at early postnatal ages. By 10 weeks of age there was a significant elevation of RA that was localized to the neural retina.. In this study, we show a high level of AHD2 and RA in the neural retina of Mitf(vit) mice relative to control mice. It is possible that this elevation of RAs contributes to the retinal degeneration observed in Mitf(vit) mice either by inducing apoptosis or by enhancing the effect of some other factor(s) involved in the apoptotic pathway.

Topics: Aldehyde Oxidoreductases; Animals; Animals, Newborn; Chromatography, High Pressure Liquid; Disease Models, Animal; Eye; Immunohistochemistry; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Pigment Epithelium of Eye; Retina; Retinal Degeneration; Retinal Dehydrogenase; Time Factors; Tretinoin

The eye is the organ whose development is the most frequently altered in response to maternal vitamin A deficiency [VAD; Warkany, J. and Schraffenberger, S. (1946). Archs Ophthalmol. 35, 150-169]. With the exception of prenatal retinal dysplasia, all the ocular abnormalities of the fetal VAD syndrome are recapitulated in mouse mutants lacking either RARalpha and RARbeta2, RARalpha and RARgamma, RARgamma and RARbeta2, or RXRalpha [Lohnes, D., Mark, M., Mendelsohn, C., Dolle, P., Dierich, A., Gorry, P., Gansmuller, A. and Chambon, P. (1994) Development 120, 2723-2748; Mendelsohn, C., Lohnes, D., Décimo, D., Lufkin, T., LeMeur, M., Chambon, P. and Mark, M. (1994) Development 120, 2749-2771; Kastner, P., Grondona, J. Mark, M., Gansmuller, A., LeMeur, M., Décimo, D., Vonesch, J.L., Dollé, P. and Chambon, P. (1994) Cell 78, 987-1003], thus demonstrating that retinoic acid (RA) is the active vitamin A metabolite during prenatal eye morphogenesis. Whether retinoids are also involved in postnatal eye development could not be investigated, as VAD newborns are not viable and the above RAR double null mutants and RXRalpha null mutants died in utero or at birth. We report here the generation of viable RARbeta2/RARgamma2 double null mutant mice, which exhibit several eye defects. The neural retina of newborn RARbeta2gamma2 mutants is thinner than normal due to a reduced rate of cell proliferation, and from day 4 shows multiple foci of disorganization of its layers. These RARbeta2gamma2 mutants represent the first genetically characterized model of retinal dysplasia and their phenotype demonstrates that RARs, and therefore RA, are required for retinal histogenesis. The RARbeta2gamma2 retinal pigment epithelium (RPE) cells display histological and/or ultrastructural alterations and/or fail to express cellular retinol binding protein I (CRBPI). Taken altogether, the early onset of the RPE histological defects and their striking colocalisation with areas of the neural retina displaying a faulty laminar organization, a reduced neuroblastic proliferation, and a lack of photoreceptor differentiation and/or increased apoptosis, make the RPE a likely target tissue of the RARbeta2gamma2 double null mutation. A degeneration of the adult neural retina, which may similarly be secondary to a defective RPE, is also observed in these mutants, thus demonstrating an essential role of RA in the survival of retinal cells. Moreover, all RARbeta2gamma2 mutants display defects in structures

Topics: Animals; Animals, Newborn; Cell Division; DNA; Eye Abnormalities; Female; Immunohistochemistry; In Situ Hybridization; Male; Mice; Mice, Mutant Strains; Microscopy, Electron; Receptors, Retinoic Acid; Retina; Retinal Degeneration; Retinal Diseases; Retinal Dysplasia; Rod Opsins; Tretinoin

To evaluate the protective effects of midkine (MK), the product of a retinoic acid-responsive gene, on constant light-induced retinal degeneration in albino Sprague-Dawley rats.. Midkine, basic fibroblast growth factor (bFGF), MK plus heparin, or buffer controls were injected intravitreally 2 days before constant light exposure. After 7 days of continuous light exposure, the eyes were perfused with fixative, bisected along the vertical meridian, embedded in paraffin, and sectioned. The degree of retinal light damage was assessed for paraffin-embedded sections by cytologic analysis, by measuring the thickness of the outer nuclear layer (ONL), and by counting the number of macrophages.. After 1 week of constant light exposure, uninjected controls and those injected with phosphate-buffered saline (PBS) lost most of the photoreceptor inner and outer segments, and the thickness of the ONL was decreased. Eyes that were injected with MK or bFGF demonstrated a significant rescue in the photoreceptor layer with a two- to threefold increase in the ONL thickness. The number of macrophages in eyes injected with MK was significantly suppressed compared with controls. Those injected with bFGF had a 1.5-fold increase in number compared with controls.. Midkine has shown strong survival-promoting activity in constant light-induced retinal degeneration, and thus has a high degree of neurotrophic activity in vivo.

Topics: Animals; Carrier Proteins; Cell Count; Cell Survival; Cytokines; Fibroblast Growth Factor 2; Heparin; Light; Midkine; Photoreceptor Cells; Proteins; Radiation Injuries, Experimental; Rats; Rats, Sprague-Dawley; Retinal Degeneration; Tretinoin

Analysis of the sucrose-density-gradient patterns of the 110 000g supernatant fractions of adult and foetal retina and pigment epithelium showed them to contain a limited number of highly specific binding sites ('receptors') for [3H]retinoic acid that sediment at approx. 2S. Binding in pigment epithelium is higher than in any tissue yet reported. A 5S binding component is also observed and is probably due to serum contamination. Fractionation studies indicate that [3H]retinoic acid binding in the retina is lower in the photoreceptor units than in the retinal inner layers. This is in contrast with previous results that show greater [3H]retinol binding in photoreceptors. Studies with dystrophic human and rat retinas, which lack the photoreceptor layers, confirm that [3H]retinoic acid binding is greater in the non-photoreceptor layers of the retina. No specific [3H]retinoic acid binding is found in corneal epithelium, although endothelium and the conjunctiva demonstrate specific 2S binding. Such differences in retinol and retinoic acid binding may indicate different roles for the two compounds in ocular tissues.

Topics: Animals; Binding Sites; Cattle; Centrifugation, Density Gradient; Chick Embryo; Chickens; Cornea; Eye; Haplorhini; Humans; Pigment Epithelium of Eye; Rats; Receptors, Drug; Retina; Retinal Degeneration; Tretinoin; Vitamin A

Topics: Animals; Disease Models, Animal; Light; Membranes; Microscopy, Electron; Microscopy, Electron, Scanning; Phagocytosis; Photoreceptor Cells; Rats; Retinal Degeneration; Temperature; Tretinoin; Visual Fields; Vitamin A Deficiency