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Retinal Degeneration (retinal + degeneration)
Selected AbstractsRetinal Degenerations: Biology, Diagnostics and TherapeuticsCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 6 2008Article first published online: 10 OCT 200 No abstract is available for this article. [source] Retinal organization in the retinal degeneration 10 (rd10) mutant mouse: A morphological and ERG studyTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2007Claudia Gargini Abstract Retinal degeneration 10 (rd10) mice are a model of autosomal recessive retinitis pigmentosa (RP), identified by Chang et al. in 2002 (Vision Res. 42:517,525). These mice carry a spontaneous mutation of the rod-phosphodiesterase (PDE) gene, leading to a rod degeneration that starts around P18. Later, cones are also lost. Because photoreceptor degeneration does not overlap with retinal development, and light responses can be recorded for about a month after birth, rd10 mice mimic typical human RP more closely than the well-known rd1 mutants. The aim of this study is to provide a comprehensive analysis of the morphology and function of the rd10 mouse retina during the period of maximum photoreceptor degeneration, thus contributing useful data for exploiting this novel model to study RP. We analyzed the morphology and survival of retinal cells in rd10 mice of various ages with quantitative immunocytochemistry and confocal microscopy; we also studied retinal function with the electroretinogram (ERG), recorded between P18 and P30. We found that photoreceptor death (peaking around P25) is accompanied and followed by dendritic retraction in bipolar and horizontal cells, which eventually undergo secondary degeneration. ERG reveals alterations in the physiology of the inner retina as early as P18 (before any obvious morphological change of inner neurons) and yet consistently with a reduced band amplification by bipolar cells. Thus, changes in the rd10 retina are very similar to what was previously found in rd1 mutants. However, an overall slower decay of retinal structure and function predicts that rd10 mice might become excellent models for rescue approaches. J. Comp. Neurol. 500:222,238, 2007. © 2006 Wiley-Liss, Inc. [source] Retinal degeneration: challenge and opportunityCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 5 2005Michael Kalloniatis BSc (Optom) MSc (Optom) PhD No abstract is available for this article. [source] The unconventional myosin-VIIa associates with lysosomesCYTOSKELETON, Issue 1 2005Lily E. Soni Abstract Mutations in the myosin-VIIa (MYO7a) gene cause human Usher disease, characterized by hearing impairment and progressive retinal degeneration. In the retina, myosin-VIIa is highly expressed in the retinal pigment epithelium, where it plays a role in the positioning of melanosomes and other digestion organelles. Using a human cultured retinal pigmented epithelia cell line, ARPE-19, as a model system, we have found that a population of myosin-VIIa is associated with cathepsin D- and Rab7-positive lysosomes. Association of myosin-VIIa with lysosomes was Rab7 independent, as dominant negative and dominant active versions of Rab7 did not disrupt myosin-VIIa recruitment to lysosomes. Association of myosin-VIIa with lysosomes was also independent of the actin and microtubule cytoskeleton. Myosin-VIIa copurified with lysosomes on density gradients, and fractionation and extraction experiments suggested that it was tightly associated with the lysosome surface. These studies suggest that myosin-VIIa is a lysosome motor. Cell Motil. Cytoskeleton 62:13,26, 2005. © 2005 Wiley-Liss, Inc. [source] Loss of photic entrainment at low illuminances in rats with acute photoreceptor degenerationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2009Domitille L. Boudard Abstract In several species, an acute injection of N -methyl- N -nitrosourea (MNU) induces a retinal degeneration characterized principally by a rapid loss of the outer nuclear layer, the other layers remaining structurally intact. It has, however, also been reported that down-regulation of melanopsin gene expression is associated with the degeneration and is detectable soon after injection. Melanopsin is expressed by a small subset of intrinsically photosensitive retinal ganglion cells and plays an important role in circadian behaviour photoentrainment. We injected MNU into Long Evans rats and investigated the ability of animals to entrain to three light/dark cycles of different light intensities (300, 15 and 1 lux). Control animals entrained their locomotor activity rhythms to the three cycles. In contrast, MNU-treated animals could only entrain properly to the 300 lux cycle. For the 15 lux cycle, their phase angle was much altered compared with control animals, and for the 1 lux cycle, MNU-injected animals were unable to photoentrain and exhibited an apparent free-run activity pattern with a period of 24.3 h. Subsequent to behavioural studies the animals were killed and rod, cone, melanopsin expression and melanopsin-expressing cells were quantified. Rod and cone loss was almost complete, melanopsin protein was reduced by 83% and melanopsin-expressing cells were reduced by 37%. Our study provides a comprehensive model of photoreceptor degeneration at the adult stage and a simple and versatile method to investigate the relation between retinal photoreceptors and the circadian system. [source] Absence of phosphoglucose isomerase-1 in retinal photoreceptor, pigment epithelium and Muller cellsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2004Simon N. Archer Abstract Macroarray analysis was used to compare equal amounts of cDNA from wild-type and rd/rd (retinal degeneration) mice, collected at P90 when photoreceptor degeneration is virtually complete. A stronger signal for the glycolytic enzyme phosphoglucose isomerase (Gpi1) was observed in the rd/rd sample. Extracellularly, Gpi1 may act as a cytokine, independently described as neuroleukin and autocrine motility factor. Retinal Gpi1 expression was investigated by Northern and Western blot analysis and immunohistochemistry. Double-labelling was performed with antibodies against Gpi1 and calbindin-D, glutamine synthetase, RPE65, calretinin and ultraviolet opsin in order to provide positive cell type identification. Northern and Western blots showed double expression levels per microgram of RNA and protein, respectively, in the rd/rd retina compared with wild-type. However, the total amount of Gpi1 protein per retina was indistinguishable. Gpi1 immunoreactivity was found in ganglion, amacrine, horizontal and bipolar cells, but not in rods, cones, pigment epithelium and Muller cells. This distribution explains why the absolute amounts of Gpi1 protein were not appreciably different between wild-type and the rd/rd phenotype, where rods and cones are absent, whilst the relative contribution of Gpi1 to the total protein and RNA pools differed. Some extracellular immunoreactivity was observed in the photoreceptor matrix around cones in freshly fixed tissue only, which could possibly reflect a role as a cytokine. We propose that glycolysis in Gpi1-negative cells proceeds entirely through the pentose phosphate pathway, creating NADPH at the cost of organic carbon. We hypothesize that the unique metabolic needs of photoreceptors justify this trade-off. [source] Spectrum of ALMS1 variants and evaluation of genotype-phenotype correlations in Alström syndrome,HUMAN MUTATION, Issue 11 2007Jan D. Marshall Abstract Alström syndrome is a monogenic recessive disorder featuring an array of clinical manifestations, with systemic fibrosis and multiple organ involvement, including retinal degeneration, hearing loss, childhood obesity, diabetes mellitus, dilated cardiomyopathy (DCM), urological dysfunction, and pulmonary, hepatic, and renal failure. We evaluated a large cohort of patients with Alström syndrome for mutations in the ALMS1 gene. In total, 79 disease-causing variants were identified, of which 55 are novel mutations. The variants are primarily clustered in exons 8, 10, and 16, although we also identified novel mutations in exons 12 and 18. Most alleles were identified only once (45/79), but several were found recurrently. Founder effects are likely in families of English and Turkish descent. We also identified 66 SNPs and assessed the functional significance of these variants based on the conserved identity of the protein and the severity of the resulting amino acid substitution. A genotype,phenotype association study examining 18 phenotypic parameters in a subset of 58 patients found suggestive associations between disease-causing variants in exon 16 and the onset of retinal degeneration before the age of 1 year (P = 0.02), the occurrence of urological dysfunction (P = 0.02), of DCM (P = 0.03), and of diabetes (P = 0.03). A significant association was found between alterations in exon 8 and absent, mild, or delayed renal disease (P = 0.0007). This data may have implications for the understanding of the molecular mechanisms of ALMS1 and provides the basis for further investigation of how alternative splicing of ALMS1 contributes to the severity of the disease. Hum Mutat 28(11),1114,1123, 2007. Published 2007 Wiley-Liss, Inc. [source] Amyloid-,(1-42) alters structure and function of retinal pigmented epithelial cellsAGING CELL, Issue 2 2009Julien Bruban Summary Age-related macular degeneration (AMD) is characterized by the formation of drusen, extracellular deposits associated with atrophy of the retinal pigmented epithelium (RPE), disturbance of the transepithelial barrier and photoreceptor death. Amyloid-, (A,) is present in drusen but its role during AMD remains unknown. This study investigated the in vitro and in vivo effects of the oligomeric form of A,(1-42) , OA,(1-42) , on RPE and found that it reduced mitochondrial redox potential and increased the production of reactive oxygen species, but did not induce apoptosis in RPE cell cultures. It also disorganized the actin cytoskeleton and halved occludin expression, markedly decreasing attachment capacity and abolishing the selectivity of RPE cell transepithelial permeability. Antioxidant pretreatment partially reversed the effects of OA,(1-42) on mitochondrial redox potential and transepithelial permeability. Subretinally injected OA,(1-42) induced pigmentation loss and RPE hypertrophy but not RPE cell apoptosis in C57BL/6 J mice. Rapid OA,(1-42)-induced disorganization of cytoskeletal actin filaments was accompanied by decreased RPE expression of the tight junction proteins occludin and zonula occludens-1 and of the visual cycle proteins cellular retinaldehyde-binding protein and RPE65. The number of photoreceptors decreased by half within a few days. Our study pinpoints the role of A, in RPE alterations and dysfunctions leading to retinal degeneration and suggests that targeting A, may help develop selective methods for treating diseases involving retinal degeneration, such as AMD. [source] Congenital DNA repair deficiency results in protection against renal ischemia reperfusion injury in miceAGING CELL, Issue 2 2009Denis Susa Summary Cockayne syndrome and other segmental progerias with inborn defects in DNA repair mechanisms are thought to be due in part to hypersensitivity to endogenous oxidative DNA damage. The accelerated aging-like symptoms of this disorder include dysmyelination within the central nervous system, progressive sensineuronal hearing loss and retinal degeneration. We tested the effects of congenital nucleotide excision DNA repair deficiency on acute oxidative stress sensitivity in vivo. Surprisingly, we found mouse models of Cockayne syndrome less susceptible than wild type animals to surgically induced renal ischemia reperfusion injury, a multifactorial injury mediated in part by oxidative damage. Renal failure-related mortality was significantly reduced in Csb,/, mice, kidney function was improved and proliferation was significantly higher in the regenerative phase following ischemic injury. Protection from ischemic damage correlated with improved baseline glucose tolerance and insulin sensitivity and a reduced inflammatory response following injury. Protection was further associated with genetic ablation of a different Cockayne syndrome-associated gene, Csa. Our data provide the first functional in vivo evidence that congenital DNA repair deficiency can induce protection from acute stress in at least one organ. This suggests that while specific types of unrepaired endogenous DNA damage may lead to detrimental effects in certain tissues, they may at the same time elicit beneficial adaptive changes in others and thus contribute to the tissue specificity of disease symptoms. [source] Functional implications for Kir4.1 channels in glial biology: from K+ buffering to cell differentiationJOURNAL OF NEUROCHEMISTRY, Issue 3 2008Michelle L. Olsen Abstract Astrocytes and oligodendrocytes are characterized by a very negative resting potential and a high resting permeability for K+ ions. Early pharmacological and biophysical studies suggested that the resting potential is established by the activity of inwardly rectifying, Ba2+ sensitive, weakly rectifying Kir channels. Molecular cloning has identified 16 Kir channels genes of which several mRNA transcripts and protein products have been identified in glial cells. However, genetic deletion and siRNA knock-down studies suggest that the resting conductance of astrocytes and oligodendrocytes is largely due to Kir4.1. Loss of Kir4.1 causes membrane depolarization, and a break-down of K+ and glutamate homeostasis which results in seizures and wide-spread white matter pathology. Kir channels have also been shown to act as critical regulators of cell division whereby Kir function is correlated with an exit from the cell cycle. Conversely, loss of functional Kir channels is associated with re-entry of cells into the cell cycle and gliosis. A loss of functional Kir channels has been shown in a number of neurological diseases including temporal lobe epilepsy, amyotrophic lateral sclerosis, retinal degeneration and malignant gliomas. In the latter, expression of Kir4.1 is sufficient to arrest the aberrant growth of these glial derived tumor cells. Kir4.1 therefore represents a potential therapeutic target in a wide variety of neurological conditions. [source] Increased expression of glial cell line-derived neurotrophic factor protects against oxidative damage-induced retinal degenerationJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Aling Dong Abstract Oxidative damage contributes to retinal cell death in patients with age-related macular degeneration or retinitis pigmentosa. One approach to treatment is to identify and eliminate the sources of oxidative damage. Another approach is to identify treatments that protect cells from multiple sources of oxidative damage. In this study, we investigated the effect of increased expression of glial cell line-derived neurotrophic factor (GDNF) in three models of oxidative damage-induced retinal degeneration. Double transgenic mice with doxycycline-inducible expression of GDNF in the retina were exposed to paraquat, FeSO4, or hyperoxia, all sources of oxidative damage and retinal cell death. Compared to controls, mice with increased expression of GDNF in the retina showed significant preservation of retinal function measured by electroretinograms, reduced thinning of retinal cell layers, and fewer TUNEL-positive cells indicating less retinal cell death. Mice over-expressing GDNF also showed less staining for acrolein, nitrotyrosine, and 8-hydroxydeoxyguanosine, indicating less oxidative damage to lipids, proteins, and DNA. This suggests that GDNF did not act solely to allow cells to tolerate higher levels of oxidative damage before initiation of apoptosis, but also reduced damage from oxidative stress to critical macromolecules. These data suggest that gene transfer of Gdnf should be considered as a component of therapy for retinal degenerations in which oxidative damage plays a role. [source] Canine inhertited retinal degenerations: update on molecular genetic research and its clinical applicationJOURNAL OF SMALL ANIMAL PRACTICE, Issue 10 2002C-T. Lin Inherited retinal degenerations in the dog include generalized progressive retinal atrophy, retinal pigment epithelial dystrophy, congenital stationary night blindness and day blindness (hemeralopia). The clinical phenotype and pathology of these diseases closely resemble some types of human inherited retinal degeneration, in particular retinitis pigmentosa, one of the most common inherited causes of blindness in man. Molecular genetic investigations aim to identify the genetic mutations underlying the canine inherited retinal degenerations. Two major research strategies, candidate gene analysis and linkage analysis, have been used. To date, candidate gene analysis has definitively identified the genetic mutations underlying nine inherited retinal degenerations, each in a different breed of dog, and linkage studies have identified genetic markers for a further retinal degeneration which is found in at least six different breeds. This review outlines the research strategy behind candidate gene and linkage studies and summarises recent results in the search for genetic causes of canine inherited retinal degenerations. The aim is to increase awareness of this rapidly changing field and to show how the research can be used to develop genetic tests for these diseases and thereby reduce the incidence of inherited eye disease in dogs. [source] Rare case of Alstrom syndrome without obesity and with short stature, diagnosed in adulthood (Case Report)NEPHROLOGY, Issue 2 2006EYUP KOÇ SUMMARY: Alstrom syndrome is a rare autosomal recessive disorder characterized by retinal degeneration, sensorineural hearing loss, obesity, type 2 diabetes mellitus and chronic nephropathy. It may be associated with acanthosis nigricans, hypergonadotropic hypogonadism, hepatic dysfunction, hepatic steatosis, hyperlipidaemia, dilated cardiomyopathy and short stature. We report a patient with Alstrom syndrome who had hypergonadotropic hypogonadism, hepatic dysfunction, hepatic steatosis and short stature with normal body weight, all of which are seen infrequently with this syndrome. [source] Marinesco-Sjögren syndrome with atrophy of the brain stem tegmentum and dysplastic cytoarchitecture in the cerebral cortexNEUROPATHOLOGY, Issue 5 2008Kenji Sakai Marinesco-Sjögren syndrome (MSS) is a progressive multisystem disease with autosomal recessive inheritance characterized by cataracts, mental retardation, and cerebellar ataxia. Recently, two causative genes for MSS, SIL1 and SARA2, have been identified. On the other hand, the histopathologic features of the CNS in this syndrome have not yet been clarified in detail. We report here the features of an autopsy case of MSS with progressive myopathy, in which atrophy of the cerebellum and brain stem tegmentum, retinal degeneration, and dysplastic cytoarchitecture in the cerebral cortex were evident. An elder brother of the patient showed quite similar symptoms, implying an autosomal recessive mode of inheritance. However, we detected no mutations in the available genes. This case appears to represent an unusual example of MSS manifesting widespread developmental anomaly and neuronal degeneration in the CNS. [source] Ca2+ -dependent Regulation of Phototransduction,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Ricardo Stephen Photon absorption by rhodopsin triggers the phototransduction signaling pathway that culminates in degradation of cGMP, closure of cGMP-gated ion channels and hyperpolarization of the photoreceptor membrane. This process is accompanied by a decrease in free Ca2+ concentration in the photoreceptor cytosol sensed by Ca2+ -binding proteins that modulate phototransduction and activate the recovery phase to reestablish the photoreceptor dark potential. Guanylate cyclase-activating proteins (GCAPs) belong to the neuronal calcium sensor (NCS) family and are responsible for activating retinal guanylate cyclases (retGCs) at low Ca2+ concentrations triggering synthesis of cGMP and recovery of the dark potential. Here we review recent structural insight into the role of the N-terminal myristoylation in GCAPs and compare it to other NCS family members. We discuss previous studies identifying regions of GCAPs important for retGC1 regulation in the context of the new structural data available for myristoylated GCAP1. In addition, we present a hypothetical model for the Ca2+ -triggered conformational change in GCAPs and retGC1 regulation. Finally, we briefly discuss the involvement of mutant GCAP1 proteins in the etiology of retinal degeneration as well as the importance of other Ca2+ sensors in the modulation of phototransduction. [source] Effect of Visible Light on Normal and P23H-3 Transgenic Rat Retinas: Characterization of a Novel Retinoic Acid Derivative Present in the P23H-3 RetinaPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2006Todd Duncan ABSTRACT Transgenic rats with the P23H mutation in rhodopsin exhibit increased susceptibility to light damage, compared with normal animals. It is known that light-induced retinal damage requires repetitive bleaching of rhodopsin and that photoreceptor cell loss is by apoptosis; however, the underlying molecular mechanism(s) leading to photoreceptor cell death are still unknown. Photoproducts, such as all- trans retinal or other retinoid metabolites, released by the extensive bleaching of rhodopsin could lead to activation of degenerative processes, especially in animals genetically predisposed to retinal degenerations. Using wild-type and transgenic rats carrying the P23H opsin mutation, we evaluated the effects of acute intense visible light on retinoid content, type and distribution in ocular tissues. Rats were exposed to green light (480,590 nm) for 0, 5, 10, 30 and 120 min. Following light treatment, rats were sacrificed and neural retinas were dissected free of the retinal pigment epithelium. Retinoids were extracted from retinal tissues and then subjected to HPLC and mass spectral analysis. We found that the light exposure affected relative levels of retinoids in the neural retina and retinal pigment epithelium of wild-type and P23H rat eyes similarly. In the P23H rat retina but not the wild-type rat retina, we found a retinoic acid-like compound with an absorbance maximum of 357 nm and a mass of 304 daltons. Production of this retinoic acid-like compound in transgenic rats is influenced by the age of the animals and the duration of light exposure. It is possible that this unique retinoid may be involved in the process of light-induced retinal degeneration. [source] cGMP-dependent cone photoreceptor degeneration in the cpfl1 mouse retinaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 17 2010Dragana Trifunovi Abstract Inherited retinal degeneration affecting both rod and cone photoreceptors constitutes one of the leading causes of blindness in the developed world. Such degeneration is at present untreatable, and the underlying neurodegenerative mechanisms are unknown, even though certain genetic causes have been established. The rd1 mouse is one of the best characterized animal models for rod photoreceptor degeneration, whereas the cpfl1 mouse is a recently discovered model for cone cell death. Because both animal models are affected by functionally similar mutations in the rod and cone phosphodiesterase 6 genes, respectively, we asked whether the mechanisms of photoreceptor degeneration in these two mouse lines share common pathways. In the present study, we followed the temporal progression of photoreceptor degeneration in the cpfl1 retina, correlated it with specific metabolic markers, and compared it with the wild-type and the rd1 situation. Similar to corresponding rd1 observations, cpfl1 cone photoreceptor cell death was associated with an accumulation of cyclic guanosine monophosphate (cGMP), activity of calpains, and phosphorylation of vasodilator-stimulated protein (VASP). Cone degeneration progressed rapidly, with a peak in cell death around postnatal day 24. Furthermore, cpfl1 cone photoreceptor migration during early postnatal development was delayed significantly compared with the corresponding wild-type retina. The finding that rod and cone photoreceptor degeneration was associated with the same metabolic markers suggests that in both cell types similar degenerative mechanisms are active. This raises the possibility that equivalent neuroprotective strategies may be used to prevent both rod and cone photoreceptor degeneration. J. Comp. Neurol. 518:3604,3617, 2010. © 2010 Wiley-Liss, Inc. [source] Retinal organization in the retinal degeneration 10 (rd10) mutant mouse: A morphological and ERG studyTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2007Claudia Gargini Abstract Retinal degeneration 10 (rd10) mice are a model of autosomal recessive retinitis pigmentosa (RP), identified by Chang et al. in 2002 (Vision Res. 42:517,525). These mice carry a spontaneous mutation of the rod-phosphodiesterase (PDE) gene, leading to a rod degeneration that starts around P18. Later, cones are also lost. Because photoreceptor degeneration does not overlap with retinal development, and light responses can be recorded for about a month after birth, rd10 mice mimic typical human RP more closely than the well-known rd1 mutants. The aim of this study is to provide a comprehensive analysis of the morphology and function of the rd10 mouse retina during the period of maximum photoreceptor degeneration, thus contributing useful data for exploiting this novel model to study RP. We analyzed the morphology and survival of retinal cells in rd10 mice of various ages with quantitative immunocytochemistry and confocal microscopy; we also studied retinal function with the electroretinogram (ERG), recorded between P18 and P30. We found that photoreceptor death (peaking around P25) is accompanied and followed by dendritic retraction in bipolar and horizontal cells, which eventually undergo secondary degeneration. ERG reveals alterations in the physiology of the inner retina as early as P18 (before any obvious morphological change of inner neurons) and yet consistently with a reduced band amplification by bipolar cells. Thus, changes in the rd10 retina are very similar to what was previously found in rd1 mutants. However, an overall slower decay of retinal structure and function predicts that rd10 mice might become excellent models for rescue approaches. J. Comp. Neurol. 500:222,238, 2007. © 2006 Wiley-Liss, Inc. [source] 4145: Analysis of mouse eye mutants as models for human diseasesACTA OPHTHALMOLOGICA, Issue 2010S JADEJA Purpose The Eumodic (European Mouse Disease Clinic) project screens mouse knockout lines and ENU induced mutants for pathological phenotypes. Initially 2 of the strains identified with an eye defect by the Sanger MGP and a strain from the ENU mutagenesis screen at MRC Harwell have been selected for further investigation. Methods Following the initial primary phenotyping, pathology; histology; and immunohistochemistry was carried out on ocular tissue collected from mutant and control animals to determine defects in eye structure and development. This gave an indication to the underlying cause of the defects seen, enabling further molecular biology analysis. Results Btb/Poz Domain-containing Protein 12 (Btbd12) is a scaffold protein required for the formation of DNA repair complexes. The mouse knockout of this gene shows corneal opacity, dilated pupils and occasional microphthalmia, modelling the phenotypes seen in human diseases of defective DNA repair. The corneas of the mutant animals exhibit increased DNA damage which is likely to be the cause of the opacification. Solute Carrier Family 9 Member 8 (Slc9a8) is a Sodium/ Hydrogen exchanger and has previously been shown to play a role in ion exchange. The Slc9a8 knockout strain appears to have retinal degeneration and the males are infertile. The ENU-induced mutant Pedv128 exhibits defects in the retinal vasculature including defective vascular patterning and increased vascular leakage. Of particular interest is that this vascular phenotype is restricted to the eyes. Conclusion Investigation of mouse eye mutants can result in a better understanding of the pathology and underlying causes of human diseases. [source] Chromosomal number aberrations and transformation in adult mouse retinal stem cells in vitroACTA OPHTHALMOLOGICA, Issue 2009M DJOJOSUBROTO Purpose The therapeutic potential of stem cells on degenerative diseases and damaged tissues such as retinal degeneration has been recognized. Generation of high numbers of retinal stem cells (RSCs) in vitro would thus be beneficial for retinal transplantation. As long-term cultivated cells might be unstable and have a risk of transformation, it is important to assess the stability of these cells. Methods We analyzed chromosomal aberrations of RSC lines isolated from adult and postnatal day 1 mouse retinas. Then, selected cell lines were tested for anchorage-dependent proliferation, and for possibility of transformation by transplantation in immunocompromised mice. Results Aneuploidy occurred in all adult cell lines, albeit to different levels. Neonatal RSCs were the most stable and displaying a normal karyotype until at least passage 9. We observed that two of the adult RCS lines tested were transformed and identified several cell cycle proteins that might support the cell continuous proliferation and transformation. Conclusion The aneuploidy level of adult RSCs did not necessarily correlate with cell transformation. Only the adult RSC lines passaged for longer period and with higher dilution ratio underwent transformation, showing that culture condition plays an important role in supporting the selection and growth of transformed cells. [source] The Bmi1 polycomb gene as a target for therapies against retinal degenerationACTA OPHTHALMOLOGICA, Issue 2009Y ARSENIJEVIC Purpose In several neurodegenerative diseases the reactivation of cell cycle proteins is a key event that precedes neuronal apoptosis. We asked whether a similar phenomenon occurs in Rd1 mice, a model of retinitis pigmentosa widely used to study photoreceptor (PR) loss. Methods We used different knockout mouse models to reveal whether proteins involved in the cell cycle regulation are responsible for photoreceptor loss in the Rd1 mouse. Results At P12, an early stage of the disease, Rd1 mice displayed an increased expression of CDK4 and CDK2 among PR nuclei. PRs also undergo DNA synthesis. At P12, the polycomb protein Bmi1 was expressed in virtually all the nuclei in the inner and outer nuclear layer of both wild-type (WT) and Rd1 mice. Bmi1 promotes cell cycle progression via the repression of tumor suppressor genes. We reasoned that Bmi1 deletion could impede the aberrant CDK reactivation that characterizes neuronal apoptosis and may therefore delay retinal degeneration. We compared the histology of WT, Rd1 and Rd1;Bmi1-/- and observed the presence of 7 rows of PRs in Rd1;Bmi1-/- mice at P33, while Rd1 littermates displayed a single scattered row of PRs. ERG recordings revealed the ability of Rd1:Bmi1-/- retinas to respond to light stimuli. Both DNA synthesis and CDK4 were strongly decreased in Rd1;Bmi1-/- mice, respectively by 70% and 50% as compared to Rd1 littermates. Conclusion In conclusion, our data show for the first time a mechanism of retina degeneration involving a reactivation of the cell cycle that precedes PR death in Rd1 mice and reveal that the partial inhibition of cell cycle re-entry strongly delays PR loss. [source] Developments in molecular genetics and electrophysiology in inherited retinal disordersACTA OPHTHALMOLOGICA, Issue 2 2006Sten Andréasson Abstract. Retinitis pigmentosa is said to be the most frequent reason for severe visual handicap among young people in Scandinavia today. Developments in the fields of electrophysiology and molecular genetics have increased our understanding of the pathophysiology of these disorders and have also improved our clinical competence, leading to a better understanding of the patient's visual handicap and his or her prognosis. This represents the first step towards fulfilling our plan for the future, which is ultimately to cure blindness caused by the different forms of hereditary retinal degeneration. This review is based on 20 years of research at the Department of Ophthalmology in Lund. [source] Increased expression of glial cell line-derived neurotrophic factor protects against oxidative damage-induced retinal degenerationJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Aling Dong Abstract Oxidative damage contributes to retinal cell death in patients with age-related macular degeneration or retinitis pigmentosa. One approach to treatment is to identify and eliminate the sources of oxidative damage. Another approach is to identify treatments that protect cells from multiple sources of oxidative damage. In this study, we investigated the effect of increased expression of glial cell line-derived neurotrophic factor (GDNF) in three models of oxidative damage-induced retinal degeneration. Double transgenic mice with doxycycline-inducible expression of GDNF in the retina were exposed to paraquat, FeSO4, or hyperoxia, all sources of oxidative damage and retinal cell death. Compared to controls, mice with increased expression of GDNF in the retina showed significant preservation of retinal function measured by electroretinograms, reduced thinning of retinal cell layers, and fewer TUNEL-positive cells indicating less retinal cell death. Mice over-expressing GDNF also showed less staining for acrolein, nitrotyrosine, and 8-hydroxydeoxyguanosine, indicating less oxidative damage to lipids, proteins, and DNA. This suggests that GDNF did not act solely to allow cells to tolerate higher levels of oxidative damage before initiation of apoptosis, but also reduced damage from oxidative stress to critical macromolecules. These data suggest that gene transfer of Gdnf should be considered as a component of therapy for retinal degenerations in which oxidative damage plays a role. [source] Canine inhertited retinal degenerations: update on molecular genetic research and its clinical applicationJOURNAL OF SMALL ANIMAL PRACTICE, Issue 10 2002C-T. Lin Inherited retinal degenerations in the dog include generalized progressive retinal atrophy, retinal pigment epithelial dystrophy, congenital stationary night blindness and day blindness (hemeralopia). The clinical phenotype and pathology of these diseases closely resemble some types of human inherited retinal degeneration, in particular retinitis pigmentosa, one of the most common inherited causes of blindness in man. Molecular genetic investigations aim to identify the genetic mutations underlying the canine inherited retinal degenerations. Two major research strategies, candidate gene analysis and linkage analysis, have been used. To date, candidate gene analysis has definitively identified the genetic mutations underlying nine inherited retinal degenerations, each in a different breed of dog, and linkage studies have identified genetic markers for a further retinal degeneration which is found in at least six different breeds. This review outlines the research strategy behind candidate gene and linkage studies and summarises recent results in the search for genetic causes of canine inherited retinal degenerations. The aim is to increase awareness of this rapidly changing field and to show how the research can be used to develop genetic tests for these diseases and thereby reduce the incidence of inherited eye disease in dogs. [source] Effect of Visible Light on Normal and P23H-3 Transgenic Rat Retinas: Characterization of a Novel Retinoic Acid Derivative Present in the P23H-3 RetinaPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2006Todd Duncan ABSTRACT Transgenic rats with the P23H mutation in rhodopsin exhibit increased susceptibility to light damage, compared with normal animals. It is known that light-induced retinal damage requires repetitive bleaching of rhodopsin and that photoreceptor cell loss is by apoptosis; however, the underlying molecular mechanism(s) leading to photoreceptor cell death are still unknown. Photoproducts, such as all- trans retinal or other retinoid metabolites, released by the extensive bleaching of rhodopsin could lead to activation of degenerative processes, especially in animals genetically predisposed to retinal degenerations. Using wild-type and transgenic rats carrying the P23H opsin mutation, we evaluated the effects of acute intense visible light on retinoid content, type and distribution in ocular tissues. Rats were exposed to green light (480,590 nm) for 0, 5, 10, 30 and 120 min. Following light treatment, rats were sacrificed and neural retinas were dissected free of the retinal pigment epithelium. Retinoids were extracted from retinal tissues and then subjected to HPLC and mass spectral analysis. We found that the light exposure affected relative levels of retinoids in the neural retina and retinal pigment epithelium of wild-type and P23H rat eyes similarly. In the P23H rat retina but not the wild-type rat retina, we found a retinoic acid-like compound with an absorbance maximum of 357 nm and a mass of 304 daltons. Production of this retinoic acid-like compound in transgenic rats is influenced by the age of the animals and the duration of light exposure. It is possible that this unique retinoid may be involved in the process of light-induced retinal degeneration. [source] 2223: Carbon monoxide as a mediator in the retinaACTA OPHTHALMOLOGICA, Issue 2010C BUCOLO Purpose Carbonic monoxide (CO) is organic gas ubiquitously synthesized in mammalian tissues by enzyme that has constitutive and inducible forms. This gas is produced as metabolic end-product in specific cell life phases, and may acts as atypical neuronal messenger. Evidence has recently accumulated suggesting that CO may be cytoprotective because its bioactions, including inhibition of apoptosis, platelet aggregation, complement activation, and inflammatory cytokine production. CO appears to be important to counteract the cytotoxicity caused by excessive production of reactive oxygen (ROS) and nitrogen (RNS) species. Methods In vitro and in vivo models. Results Induction of heme oxygenase (HO)-1 by hemin has been found to prevent retinal cell death after ischemia provoked by ocular hypertension in rats. The LPS-induced expression of pro-inflammatory cytokines, in rat eye, is also inhibited by CO. Interestingly, drugs active as inhibitors of iNOS block CO-induced increases in cGMP in the retina.Drugs inhibiting NO formation by acting on iNOS activity have been found to potently reduce intraocular pressure. Studies from our lab showed that an increase of CO availability by hemin or carbon monoxide-releasing molecules lower the intraocular pressure, suggesting a suppress action of iNOS-derived NO production. Conclusion A better understanding of CO regulation may lead to new therapeutic options that are safer and more efficacious than currently available treatments for various sight-threatening eye diseases, such as retinal degenerations. [source] | |||||||||||||||||||||||||