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PubMed1992

Transgenic mice with a rhodopsin mutation (Pro23His): a mouse model of autosomal dominant retinitis pigmentosa.

We inserted into the germline of mice either a mutant or wild-type allele from a patient with retinitis pigmentosa and a missense mutation (P23H) in the rhodopsin gene. All three lines of transgenic mice with the mutant allele developed photoreceptor degeneration; the one with the least severe retinal photoreceptor degeneration had the lowest transgene expression, which was one-sixth the level of endogenous murine rod opsin. Of two lines of mice with the wild-type allele, one expressed approximately equal amounts of transgenic and murine opsin and maintained normal retinal function and structure. The other expressed approximately 5 times more transgenic than murine opsin and developed a retinal degeneration similar to that found in mice carrying a mutant allele, presumably due to the overexpression of this protein. Our findings help to establish the pathogenicity of mutant human P23H rod opsin and suggest that overexpression of wild-type human rod opsin leads to a remarkably similar photoreceptor degeneration.

Animals↗
PubMedDate not supplied

Strategies for identification of mutations causing hereditary retinal diseases in dogs: evaluation of opsin as a candidate gene.

Progressive retinal atrophy (PRA), like retinitis pigmentosa (RP) in man, represents a clinical classification grouping together a variety of hereditary diseases of the visual cells which have broadly similar clinical characteristics. At least six distinct autosomal recessive and one X-linked retinal disease locus have been identified. As one of the strategies to look for the gene defect causing the different forms of PRA, we are examining first the most promising candidate genes. These include those coding for photoreceptor-specific structural proteins and enzymes of the phototransduction pathway, especially those reported to cause RP. Preeminent among these candidates is the gene for rod opsin, in which multiple causative mutations have been identified in both dominant and recessive forms of RP. In addition, mutations in this gene are also causally associated with congenital stationary night blindness (CSNB) in man. We have used two strategies to examine the rod opsin gene for association with inherited retinal disease in dogs: (1) linkage to determine cosegregation of the disease locus with an intragenic polymorphic marker in the opsin gene in those breeds where suitable informative pedigrees were available; and (2) scanning the coding sequence of the gene in cases where only a limited number of affected or obligate heterozygous samples were available for a breed. We conclude that mutations in the rod opsin gene are not associated with PRA or CSNB in the 11 different dog breeds tested.

Animals↗
PubMed1997

Spatial and temporal expression of cone opsins during monkey retinal development.

The primate retina requires a coordinated series of developmental events to form its specialized photoreceptor topography. In this study, the temporal expression of cone photoreceptor opsin was determined in Macaca monkey retina. Markers for mRNA and protein that recognize short wavelength (S) and long/medium wavelength (L/M) opsin were used to determine (1) the temporal and spatial patterns of opsin expression, (2) the spatial relationship between S and L/M cones at the time of initial opsin expression, and (3) the relative time of cone and rod opsin expression (Dorn et al. [1995] Invest. Ophthalmol. Vis. Sci. 36:2634-2651). Adult cone outer segments were recognized by either L/M or S opsin antiserum. Of all adult cone inner segments, 88-90% contained L/M opsin mRNA, whereas 10-12% contained S opsin mRNA. Fetal cones initially showed cell membrane as well as outer segment labeling for opsin protein, but cell membrane labeling disappeared by birth. No cones at any age contained markers for both S and L/M opsin mRNA or protein. S and L/M opsin protein appeared in the fovea at fetal day 75. Once opsin expression progressed beyond the fovea, both mRNA and protein for S opsin were consistently detected more peripherally than L/M opsin. Cones at the peripheral edge of S opsin expression had basal telodendria that appeared to reach toward neighboring cones. Because interactions between cone populations could organize the cone mosaic, the spatial relationship between S cones and the first cones to express L/M protein was analyzed quantitatively by using double-label immunocytochemistry. No consistent relationship was found between these two cone populations. Cones are generated at least 1 week before rods across monkey retina. However, rod opsin protein appears in and around the fovea at fetal day 66, 1 week before cone opsin protein. This suggests that independent local factors control differentiation in these two photoreceptor populations.

Aging↗
PubMed1989

A comparison of some photoreceptor characteristics in the pineal and retina. II. The Djungarian hamster (Phodopus sungorus).

A rod-specific antiserum was used to immunolabel elements within the retina and pineal of the adult Djungarian hamster and Welsh Mountain sheep. In the retina immunostaining was localized to the outer segments and perikarya of photoreceptor cells, while in the pineal limited numbers of labelled pinealocytes were scattered throughout the gland. An enzyme-linked immunosorbent assay (ELISA) was then used to obtain a quantitative measure of rod opsin in total eye and pineal extracts from the Djungarian hamster. Total rod opsin (+/- SEM) in the eye was measured by absorbance spectroscopy (1.88 +/- 0.10 nmoles opsin/eye) and by using the ELISA (1.75 +/- 0.02 nmoles opsin/eye). The opsin content from a total of 56 pineals gave a mean value of 0.34 +/- 0.01 pmoles opsin/pineal. Since a functional photopigment should be coupled in a 1:1 ratio to a chromophore, we investigated whether we could identify 11-cis and/or all-trans retinaldehydes in the pineal extracts by quantitative extraction and HPLC analysis as the oximes. No evidence of 11-cis or all-trans retinaloxime could be found, the chromatograms were indistinguishable from those produced by extracts of cortical brain tissue. We conclude that the opsin present within the adult hamster pineal is not coupled to the common vertebrate retinaldehyde chromophore, and as a result, is unlikely to be part of a functional photopigment.

Adaptation, Physiological↗
PubMed2000

Development of stable cell lines expressing high levels of point mutants of human opsin for biochemical and biophysical studies.

Stable HEK293S cell lines expressing high levels of normal and mutant human rod opsins were generated. Cellular expression is uniform across a population. Secondary overexpression of the same opsin transgene linked to a different drug selection marker (hygro(R)) yielded expression clones with increased opsin levels compared to the neo(R) parent strain. Wild-type and mutant human opsins regenerate with native chromophore and demonstrate spectroscopic properties consistent with previous reports of bovine opsin mutants. HEK293S cells can be grown in larger scale suspension culture (10(9) cells/liter) or in roller bottles (10(8) cells/bottle) to facilitate milligram-order preparations of purified pigments. These cell lines should be useful in any time-resolved spectroscopic or biophysical experiments that require either uniform cellular levels of opsin protein or regenerable pigment, or large amounts of purified visual pigment. They should also be useful in experiments where uniform constitutive levels of a given mutant human visual pigment are needed in each cell. These and similar types of constitutive or inducible cell lines may also be useful for studying mechanisms of human cell death that occur by mutations in the human rod opsin gene.

Amino Acid Substitution↗
PubMed2002

The retina of Spalax ehrenbergi: novel histologic features supportive of a modified photosensory role.

PURPOSE: The retina of the blind mole rat Spalax ehrenbergi was compared with other vertebrate photosensitive organs in an attempt to correlate its histologic organization with a presumptive nonvisual photoreceptor role. METHODS: The eyes of eight adult animals were analyzed by light and electron microscopy, using conventional staining and immunolabeling with antibodies against phototransduction proteins and calretinin. RESULTS: Rods accounted for most of the photoreceptor cells in the Spalax retina, although their morphology is dissimilar to that of sighted mammals, in that they contained only rudimentary outer segments. The latter showed strong rod-opsin and transducin immunoreactions. The phagosomes in the retinal pigmentary epithelium were also rod-opsin positive. Synapses were evident at the photoreceptor cells pedicles. Occasionally, several synaptic active sites were present, suggesting cone cell origin; however, cone-opsin was not immunodetected in the study samples. Synaptic ribbon fields, sometimes distant to the active sites, resembled those found in the vertebrate pineal. The other retinal layers were somewhat less organized than in sighted mammals. Some cells were displaced and the calretinin-positive inner plexiform layer had no sublayers. Calretinin immunolabeling was found in horizontal, amacrine, and ganglion cells. Folding of the retina produced rosette-like images similar to those reported before in the retina of nocturnal mammals and in the avian pineal gland. CONCLUSIONS: These data suggest that the retina of the mole rat has undergone evolutionary restructuring to a photoreceptive pineal-like organization. This supports the thesis that the photoreceptor cells of this unique organ have been reprogrammed during the subterranean adaptation of Spalax, from their original visual function to mediating photoperiodic regulation.

Animals↗
PubMed1996

Temporal expression of rod and cone opsins in embryonic goldfish retina predicts the spatial organization of the cone mosaic.

PURPOSE: Cone photoreceptors in teleost fish retina are organized into a precise, crystalline mosaic in which the four spectral subtypes have a consistent position relative to each other. The objective of the current study was to describe the spatial and temporal progression of photoreceptor differentiation in the embryonic goldfish retina to understand how the retinal cone mosaic might be produced. METHODS: To identify developing photoreceptors when they first begin to express a specific opsin, the authors used in situ hybridization with cRNA probes generated from cDNA for rod opsin and red, green, blue, and ultraviolet cone opsins from goldfish (Carassius auratus). RESULTS: In the retina, rod opsin was expressed first, and it was restricted to a small patch of regularly spaced, precocious rods located near the ventronasal edge of the retina, close to the choroid fissure. The patch enlarged by recruitment of additional rods in a circular path, moving from ventral to nasal to dorsal to temporal retina. Expression of cone opsins began approximately 10 hours after rod opsin was first expressed, and differentiation of cone photoreceptors followed the spatial pattern laid down by the early rods. The temporal order of onset of cone opsin expression was red, then green, then blue, then ultraviolet. When rod and red cone opsin probes were combined, the number of labeled cells was additive, suggesting that these two opsins are expressed in separate populations of photoreceptors. CONCLUSIONS: The onset of opsin expression in goldfish retina follows a highly ordered spatio-temporal pattern. Early differentiation and regular spacing of the precocious rods was unexpected and suggested that they may play a role in cone mosaic patterning. The order of subsequent cone opsin expression was related to the relative positions of cone subtype in the mosaic, suggesting the possibility that inductive interactions among developing photoreceptors may be responsible for patterning the cone mosaic array.

Animals↗
PubMed2006

Vertebrate opsins belonging to different classes vary in constitutively active properties resulting from salt-bridge mutations.

Vertebrate opsins are classified into one of five classes on the basis of amino acid similarity. These classes are short wavelength sensitive 1 and 2 (SWS1, SWS2), medium/long wavelength sensitive (M/LWS), and rod opsin like 1 and 2 (RH1, RH2). In bovine rod opsin (RH1), two critical amino acids form a salt bridge in the apoprotein that maintains the opsin in an inactive state. These residues are K296, which functions as the chromophore binding site, and E113, which functions as the counterion to the protonated Schiff base. Corresponding residues in each of the other vertebrate opsin classes are believed to play similar roles. Previous reports have demonstrated that mutations in these critical residues result in constitutive activation of transducin by RH1 class opsins in the absence of chromophore. Additionally, recent reports have shown that an E113Q mutation in SWS1 opsin is constitutively active. Here we ask if the other classes of vertebrate opsins maintain activation characteristics similar to that of bovine RH1 opsin. We approach this question by making the corresponding substitutions which disrupt the K296/E113 salt bridge in opsins belonging to the other vertebrate opsin classes. The mutant opsins are tested for their ability to constitutively activate bovine transducin. We demonstrate that mutations disrupting this key salt bridge produce constitutive activation in all classes. However, the mutant opsins differ in their ability to be quenched in the dark state by the addition of chromophore as well as in their level of constitutive activation. The differences in constitutive activation profiles suggest that structural differences exist among the opsin classes that may translate into a difference in activation properties.

Amino Acid Sequence↗
PubMed2006

Decrease of cone opsin mRNA in experimental ocular hypertension.

PURPOSE: This study was designed to test the hypothesis that photoreceptors are adversely affected in glaucoma. As a measure of this effect, we examined the levels of rod opsin, and red/green and blue cone opsin mRNAs in monkeys with experimental ocular hypertension and glaucoma and in human eyes from donors with diagnosed glaucoma. METHODS: Experimental ocular hypertension was induced in one eye of 19 cynomolgous and 2 rhesus monkeys by laser ablation of the trabecular meshwork. In 15 monkeys, the elevated IOP was reduced by trabeculectomy. When the animals had experienced prolonged elevations of IOP (128 to 260 days), they were killed and the eyes enucleated. Fresh retinal tissue from the macula, inferotemporal retina (mid-peripheral), and far peripheral regions were harvested from some animals using a 3 mm trephine. The remaining retinas from these monkeys, and whole retinas from other animals were fixed. RNA isolated from each trephined sample was used for RNase Protection Analysis or real time PCR analysis to quantify opsin mRNA levels from different photoreceptor cell types. Fixed tissue was used for in situ hybridization studies. Human donor eyes (7 glaucoma and 4 control) were obtained from eye banks. All human specimens were used for in situ hybridization studies. RESULTS: Quantitative mRNA analysis and in situ hybridization studies both showed a reduction in the expression of red/green and blue cone opsin mRNAs in 6 monkey eyes with chronic ocular hypertension, relative to the contralateral eye. No loss of rod opsin mRNA was observed. The principal reduction occurred in cells of the mid-peripheral retina, a region of retina that often shows early and progressive damage in humans with glaucoma. In monkeys with ocular hypertension followed by trabeculectomy, there was a similar decrease in cone opsin mRNAs, but only in six out of fifteen (40%) of the monkeys. The decrease in these animals was correlated with a significantly elevated IOP at some time during the 2 weeks prior to euthanization and not with the extent of glaucomatous damage. Of the 7 human eyes with diagnosed glaucoma that were examined, 5 showed a decrease of cone opsin mRNA in the mid-peripheral retina, whereas none of the 4 normal eyes examined showed a decrease. CONCLUSIONS: Ocular hypertension leading to glaucoma also affects the outer retina, particularly the cone photoreceptors. We speculate that these cells become stressed leading to a disruption in the expression of normal genes, such as that encoding opsin. There is some evidence that this effect is reversible, when IOP levels are reduced.

Aged↗
PubMed2000

Vertebrate ancient (VA) opsin and extraretinal photoreception in the Atlantic salmon (Salmo salar).

A member of a new photopigment family first isolated from teleost fish, vertebrate ancient (VA) opsin, has recently been shown to form a functional photopigment and to be expressed within a subset of horizontal and amacrine cells of the inner retina. These sites of expression (and structural features) of VA opsin suggest that this photopigment might mediate non-image-forming light-detection tasks. We attempted to gain support for this hypothesis by examining the expression of VA opsin within the central nervous system (CNS) (pineal and deep brain) of the Atlantic salmon Salmo salar. In addition, we examined the sites of rod-opsin, cone-opsin and &agr; -transducin expression within the salmon CNS to provide a more complete description of the extraretinal photoreceptors of a teleost vertebrate. We show that multiple populations of cells within the salmon CNS appear to contain photoreceptors: VA opsin was strongly expressed in the pineal organ and in bilateral columns of subependymal cells in the epithalamus; anti-cone-opsin antibodies labelled cells within the pineal and numerous cells in the anterior hypothalamus (suprachiasmatic nucleus, nucleus preopticus magnocellularis, nucleus preopticus parvocellularis); anti-rod-opsin antibodies labelled cells within the pineal but no other areas within the central brain; and anti- &agr; -transducin antibodies labelled cells within the pineal and the ventral telencephalon. Collectively, our results suggest that VA opsin is a photopigment specialised for irradiance detection tasks within the eye, pineal and central brain, and that the salmon has multiple and varied populations of photoreceptors within the CNS. We review the significance of these findings within the broad context of vertebrate extraretinal photoreception.

Animals↗
PubMed2003

Correlation of regenerable opsin with rod ERG signal in Rpe65-/- mice during development and aging.

PURPOSE: RPE65 has been shown to be essential for the production of 11-cis retinal by the retinal pigment epithelium. Mutations in RPE65 are known to be associated with severe forms of early-onset retinal dystrophy. This project was designed to determine the amount of regenerable opsin in Rpe65-/- mice during development and aging, and to examine the function of this rhodopsin by electroretinography (ERG). METHODS: Young and aged Rpe65-/- and wild-type (WT) mice were dark adapted. Endogenous rhodopsin and regenerable opsin were measured using absorption-difference spectrophotometry. Photoreceptor function was assessed with scotopic single-flash ERGs and photoreceptors were counted in histologic sections. Opsin's primary structure was analyzed by mass-spectrometric mapping. RESULTS: Unlike WT mice, amounts of regenerable opsin in Rpe65-/- mice decreased significantly with age, which correlated with a decrease in the number of photoreceptors and a decline in ERG amplitudes. Opsin structure, however, did not change. No endogenous levels of rhodopsin were measurable in the Rpe65-/- mice (detection limit: 0.225 pmol). 11-cis Retinal injections resulted in the regeneration of similar amounts of rhodopsin and improved rod function in a comparable way, irrespective of age. CONCLUSIONS: In the aged Rpe65-/- mouse, opsin levels decrease because of the loss of photoreceptors. The remaining opsin is structurally intact, and the components of the phototransduction cascade and the retinal circuitry remain functional, despite the absence of normal photoreceptor activity.

Aging↗
PubMed1999

Morphological, physiological, and biochemical changes in rhodopsin knockout mice.

Mutations in rod opsin, the visual pigment protein of rod photoreceptors, account for approximately 15% of all inherited human retinal degenerations. However, the physiological and molecular events underlying the disease process are not well understood. One approach to this question has been to study transgenic mice expressing opsin genes containing defined mutations. A caveat of this approach is that even the overexpression of normal opsin leads to photoreceptor cell degeneration. To overcome the problem, we have reduced or eliminated endogenous rod opsin content by targeted gene disruption. Retinas in mice lacking both opsin alleles initially developed normally, except that rod outer segments failed to form. Within months of birth, photoreceptor cells degenerated completely. Retinas from mice with a single copy of the opsin gene developed normally, and rods elaborated outer segments of normal size but with half the normal complement of rhodopsin. Photoreceptor cells in these retinas also degenerated but did so over a much slower time course. Physiological and biochemical experiments showed that rods from mice with a single opsin gene were approximately 50% less sensitive to light, had accelerated flash-response kinetics, and contained approximately 50% more phosducin than wild-type controls.

Animals↗
PubMed2005

Targeted effects of retinoic acid signaling upon photoreceptor development in zebrafish.

Retinoic acid (RA) is a signaling molecule important for photoreceptor development in vertebrates. The purpose of this study was to examine the mechanisms of the effects of RA upon developing rod and cone photoreceptors in the embryonic zebrafish. Exposure to exogenous RA increased the number of photoreceptors expressing rod opsin and red cone opsin, and decreased the number of photoreceptors expressing the blue and UV cone opsins, suggesting targeted effects of RA on photoreceptor development. RA exposure also increased opsin expression in individual rods and red cones, but decreased opsin expression in individual blue and UV cones, as indicated by differences in the strength of opsin hybridization in identified photoreceptors. RA exposure did not, however, significantly alter quantitative measures of photoreceptor pattern in a manner expected for changes in photoreceptor fate. These observations collectively indicate that RA treatment does not affect photoreceptor fate, but rather differentially influences opsin transcription in determined photoreceptors. An enzyme involved in RA synthesis, RALDH2, was immunocytochemically localized to retinal progenitor cells and the retinal pigmented epithelium (RPE), suggesting the presence of RA in the vicinity of developing photoreceptors. However, expression of an RA response element-driven transgene was restricted to the RPE, retinal progenitors, and a small population of neurons in ventral retina, suggesting that the endogenous RA signaling system is spatially limited within the eye.

Aldehyde Oxidoreductases↗
PubMed1984

Dark noise in the outer segment membrane current of green rod photoreceptors from toad retina.

The outer segment membrane current of single green rods from toad retina was recorded with a suction electrode, and the rate of spontaneous noise events similar to single-photon responses was measured at different temperatures. The activation energy, Gibbs free energy of activation, and entropy of activation for the process producing spontaneous events were similar to the values reported for thermal isomerization of free 11-cis-retinal (Hubbard, 1966), suggesting that thermal isomerization of the chromophore may be the trigger for the spontaneous events. The apparent rate constant for thermal activation of the green rod photopigment was about 4 times higher than in red rods but about 1000 times lower than for free 11-cis-retinal. Thus, both red and green rod opsin appear to stabilize 11-cis-retinal against thermal isomerization, but green rod opsin is somewhat less effective. The speed of the average dim-flash response increased as temperature was raised, as reported previously in both cone and rod photoreceptors. The reciprocal of the time-to-peak of the dim-flash response had an average Q10 of 3.3 between 20 and 30 degrees C. Changing temperature shifted the time scale of the response without altering response wave form, suggesting that all delay stages shaping the light response were approximately equally affected by temperature. At temperatures greater than 25 degrees C, flash responses were sometimes biphasic, i.e. inward dark current first decreased after a flash, then transiently increased beyond the resting dark level.

Animals↗
PubMedDate not supplied

Mutually exclusive expression of the L and M pigment genes in the human retinoblastoma cell line WERI: Resetting by cell division.

The key steps in the evolution of full trichromatic color vision in primates include duplication of the ancestral pigment gene to form the L and M pigment gene array on the X chromosome, mutually exclusive expression of the L and M pigment genes in cone photoreceptors, and formation of a retinal mosaic with randomly distributed L and M cones. Previous work using transgenic mice has indicated that a locus control region adjacent to this array of genes plays an important role in their mutually exclusive expression in respective cone cells (Smallwood et al., 2002). However, the mechanism by which this is accomplished is unknown. We searched for a cellular model system to investigate the mechanism of this mutually exclusive expression. We previously showed that the undifferentiated human retinoblastoma cell line WERI expresses L and M cone opsin but not rod opsin genes. We now show that WERI cells express the L and M pigment genes in a mutually exclusive manner, in that either L or M pigment mRNA is expressed in a single cell. Importantly, clonal analysis showed that single WERI cells that express either L or M generate, upon cell division produce, a mixed population of L- or M-expressing cells. These results indicate, first, that cell division resets L or M pigment gene expression, most likely due to disassembly and reassembly of LCR-promoter DNA-protein complexes during cell division. Second, a retinal mosaic with near-random distribution of L and M cones may have been generated automatically after duplication of the ancestral gene to form the L and M pigment genes. Third, determination of L and M cone identity may not require external molecular cues during differentiation, and is consistent with the idea that L and M cones are not intrinsically different.

Blotting, Northern↗
PubMed1996

Developmentally important DNA elements within the bovine opsin upstream region.

PURPOSE: Nuclear run-on analysis has documented three categories of opsin gene expression during bovine fetal retinal development: basal levels of transcription occurring before 6 months gestation; opsin-specific enhanced levels of fetal transcription at 7-7.5 months gestation; and a switch from fetal to adult transcription, where transcriptional activity acquires a sarkosyl sensitive component in the adult. To begin determining the mechanism of these multiple levels of gene regulation, DNA regulatory elements within 2.1 kb of the rod opsin upstream region were identified in fetal and adult bovine retinal extracts that represented the transcriptional activities characteristic of each stage of opsin gene expression. METHODS: DNAse I footprint experiments were performed on fetal and adult bovine retinal extracts from each of the developmental stages of opsin expression. RESULTS: Ten regions of protection were mapped and the level of protection was quantitated as a function of the developmental stage. CONCLUSIONS: The 10 DNA elements identified fell into three categories of developmental protection: those elements that were protected similarly at each developmental stage; those elements that were more highly protected when opsin transcription was at basal levels (i.e., less than 6 months gestation); and those elements that were more highly protected in fetal ages as compared to the adult animal. These elements are likely to be important in the developmental regulation of rod opsin gene expression.

Animals↗
PubMed2004

The effect of retinal ganglion cell injury on light-induced photoreceptor degeneration.

PURPOSE: To determine the effect of optic nerve transection (ONT) and excitotoxic retinal ganglion cell (RGC) injury on light-induced photoreceptor degeneration. METHODS: Age- and sex-matched rats underwent unilateral ONT or received intravitreal injections of N-methyl-D-aspartate (NMDA). The fellow eye received sham treatment, and 7 or 21 days later each eye was subjected to an intense photic injury. Maximum a- and b-wave amplitudes of the flash electroretinogram (ERG) were measured at baseline, after the RGC insult, and 5 days after the photic injury. Semiquantitative reverse transcription-polymerase chain reaction analysis and immunoblot analysis were used to assess rod opsin mRNA and rhodopsin kinase protein levels and to measure defined trophic factors 7 or 21 days after ONT or injection of NMDA. Structural changes after the insults were determined histologically and immunohistochemically. RESULTS: ONT caused time-dependent reductions in the mean a- and b-wave amplitudes. Seven days after intravitreal NMDA the b-wave amplitude was reduced, but the a-wave was unaffected. ONT and NMDA injection attenuated the light-induced reductions in the a- and b-wave. Rod opsin mRNA levels and rhodopsin kinase protein levels were also significantly greater in the axotomized and NMDA-treated eyes compared with the sham-treated fellow eyes after the photic injury. Structural protection in the RGC-injured eyes was also evident histologically. Fibroblast growth factor (FGF)-2, ciliary neurotrophic factor (CNTF), and glial fibrillary acidic protein (GFAP) were significantly upregulated after ONT and NMDA. CONCLUSIONS: ONT and intravitreal injection of NMDA protect against subsequent photic injury. This protection may relate to the activation of retinal glial cells and the possible action of trophic factors such as FGF-2 and CNTF.

Animals↗
PubMed2004

Otx2 homeobox gene induces photoreceptor-specific phenotypes in cells derived from adult iris and ciliary tissue.

PURPOSE: It remains unclear which gene induction effectively generates photoreceptor-specific phenotypes from nonretinal tissues. The purpose of this study was to determine whether Crx and Otx2--homeobox genes related to photoreceptor development--can induce the generation of these phenotypes in cells derived from adult ciliary and iris tissue and in mesencephalon-derived neural stem cells. METHODS: Crx and Otx2 were transferred into adult rat ciliary- and embryonic mesencephalon-derived neurospheres and adult rat iris-derived cells with the aid of a recombinant retrovirus. The presence of photoreceptor-specific phenotypes was confirmed by immunocytochemistry and Western blot analysis. RESULTS: More than 90% of the Crx- and Otx2-transfected ciliary- and iris-derived cells exhibited rod opsin immunoreactivity, whereas few of the similarly transfected mesencephalon-derived neural stem cells expressed rod opsin. At least two additional key components of the phototransduction cascade, recoverin and Gdeltat1, were expressed by Crx- and Otx2-transfected iris-derived cells. CONCLUSIONS: Crx and Otx2 effectively induced the generation of photoreceptor-specific phenotypes from ciliary- and iris-derived cells. That both Crx and Otx2 induced phenotype generation in cells derived from iris or ciliary tissue may suggest an approach to photoreceptor cell preparation for retinal transplantation.

Animals↗