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ABSTRACT: The small GTPase CDC42 has pleiotropic functions during development and in the adult. These functions include intra- as well as intercellular tasks such as organization of the cytoskeleton and, at least in epithelial cells, formation of adherens junctions. To investigate CDC42 in the neuronal retina, we generated retina-specific Cdc42-knockdown mice (Cdc42-KD) and analyzed the ensuing consequences for the developing and postnatal retina. Lack of CDC42 affected organization of the developing retina as early as E17.5, prevented correct tissue lamination, and resulted in progressive retinal degeneration and severely reduced retinal function of the postnatal retina. Despite the disorganization of the retina, formation of the primary vascular plexus was not strongly affected. However, both deeper vascular plexi developed abnormally with no clear layering of the vessels. Retinas of Cdc42-KD mice showed increased expression of pro-survival, but also of pro-apoptotic and pro-inflammatory genes and exhibited prolonged Müller glia hypertrophy. Thus, functional CDC42 is important for correct tissue organization already during retinal development. Its absence leads to severe destabilization of the postnatal retina with strong degeneration and loss of retinal function.
PLoS ONE 01/2013; 8(1):e53806. · 4.09 Impact Factor
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ABSTRACT: Blinding diseases of the retina are frequently characterized by loss of photoreceptor cells. The retinal degeneration 10 (rd10) mouse expresses a mutant form of rod phosphodiesterase leading to autosomal recessive photoreceptor degeneration. In contrast to rd1, rd10 mice have remaining rod function mimicking more closely most forms of human Retinitis Pigmentosa. Here we use morphology, biochemistry, retinal whole mounts, real-time PCR, Western blotting and immunofluorescence to compile a comprehensive report on progression of retinal degeneration in the rd10 retina up to one year of age. We show that retinal development, morphology, gene expression pattern and retinal vasculature was normal until postnatal day 15. Thereafter, a bi-phasic pattern of rod cell death emerged with a first rapid phase peaking around 3 weeks of age followed by a slower second phase. Death of cone cells followed with a delay and vessel dropout was prominent in the retinal periphery of 6 months old rd10 mice. At one year of age, RPE atrophy was evident. The degenerating retina rapidly induced expression of transcriptional regulators Atf3 and Cebpd. Induction of Atf3 was transient and lasted only for several days at the beginning of degeneration whereas levels of Cebpd remained elevated throughout the period of photoreceptor loss. Several protective genes such as Lif, Edn2 and Fgf2 which are implicated in a potent endogenous survival pathway, and Mt1 and Mt2 were strongly upregulated in the rd10 retina. In addition, increased expression of Casp1 and Il1b suggested an inflammatory response.
Experimental Eye Research 04/2012; 99:17-26. · 3.26 Impact Factor
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Anna Egger, Marijana Samardzija,
Vithiyanjali Sothilingam,
Naoyuki Tanimoto,
Christina Lange,
Silvia Salatino,
Lei Fang,
Marina Garcia-Garrido,
Susanne Beck,
Michal J Okoniewski,
Albert Neutzner,
Mathias W Seeliger,
Christian Grimm,
Christoph Handschin
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ABSTRACT: The peroxisome proliferator-activated receptor γ coactivator 1 (PGC-1) proteins are key regulators of cellular bioenergetics and are accordingly expressed in tissues with a high energetic demand. For example, PGC-1α and PGC-1β control organ function of brown adipose tissue, heart, brain, liver and skeletal muscle. Surprisingly, despite their prominent role in the control of mitochondrial biogenesis and oxidative metabolism, expression and function of the PGC-1 coactivators in the retina, an organ with one of the highest energy demands per tissue weight, are completely unknown. Moreover, the molecular mechanisms that coordinate energy production with repair processes in the damaged retina remain enigmatic. In the present study, we thus investigated the expression and function of the PGC-1 coactivators in the healthy and the damaged retina. We show that PGC-1α and PGC-1β are found at high levels in different structures of the mouse retina, most prominently in the photoreceptors. Furthermore, PGC-1α knockout mice suffer from a striking deterioration in retinal morphology and function upon detrimental light exposure. Gene expression studies revealed dysregulation of all major pathways involved in retinal damage and apoptosis, repair and renewal in the PGC-1α knockouts. The light-induced increase in apoptosis in vivo in the absence of PGC-1α was substantiated in vitro, where overexpression of PGC-1α evoked strong anti-apoptotic effects. Finally, we found that retinal levels of PGC-1 expression are reduced in different mouse models for retinitis pigmentosa. We demonstrate that PGC-1α is a central coordinator of energy production and, importantly, all of the major processes involved in retinal damage and subsequent repair. Together with the observed dysregulation of PGC-1α and PGC-1β in retinitis pigmentosa mouse models, these findings thus imply that PGC-1α might be an attractive target for therapeutic approaches aimed at retinal degeneration diseases.
PLoS ONE 01/2012; 7(2):e31272. · 4.09 Impact Factor
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ABSTRACT: In lower vertebrates, such as fish, Müller glia plays an essential role in the restoration of visual function after retinal degeneration by transdifferentiating into photoreceptors and other retinal neurons. During this process, Müller cells re-enter the cell cycle, proliferate, and migrate from the inner nuclear layer (INL) to the photoreceptor layer where they express photoreceptor-specific markers. This process of Müller cell transdifferentiation is absent in mammals, and the loss of photoreceptors leads to permanent vision deficits.The mechanisms underlying the failure of mammalian Müller cells to behave as stem cells after photoreceptor degeneration are poorly understood. In the present study, we show that photoreceptor injury induces migration of PAX6-positive Müller cell nuclei toward the outer part of the INL and into the inner part of the outer nuclear layer. These cells express markers of the cell cycle, suggesting an attempt to re-enter the cell cycle similarly to lower vertebrates.However, mouse Müller cells do not proliferate in response to photoreceptor injury implying a blockade of the S-phase transition. Our results suggest that a release of the S-phase blockade may be crucial for Müller cells to successfully transdifferentiate and replace injured photoreceptors in mammals.
Glia 07/2011; 59(7):1033-46. · 4.82 Impact Factor
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ABSTRACT: Hypoxic preconditioning activates hypoxia-inducible transcription factors (HIFs) in the retina and protects photoreceptors from light-induced retinal degeneration. The authors tested whether photoreceptor-specific activation of HIFs in normoxia is sufficient for protection.
Rod-specific Vhl knockdown mice were generated using the Cre-lox system with the rod opsin promoter controlling expression of CRE recombinase to stabilize HIF transcription factors in normoxic rods. Cell death was induced by light exposure and quantified by ELISA. Rhodopsin was quantified by spectrophotometry. Gene expression was analyzed by real-time PCR, and levels of proteins were determined by Western blotting. Morphology was investigated by light microscopy and retinal function tested by ERG.
The rod-specific Vhl knockdown stabilized HIF-α proteins and induced expression of HIF target genes in retinas of 10-week-old mice under normoxic conditions. Retinal morphology and function were normal. At 36 hours after exposure to excessive light, Vhl knockdowns showed significantly less photoreceptor cell death than did wild-type controls. Ten days after light exposure, however, photoreceptor degeneration in Vhl knockdowns was similar to that of control animals. Vhl knockdowns expressed Fgf2 at higher basal levels before light exposure. After light exposure, however, expression of Fgf2 was not significantly different from that of wild-type controls.
Artificial activation of HIF transcription factors in normoxic photoreceptors results in an increased basal expression of Fgf2 that may contribute to a transient protection of rods against light damage. Full photoreceptor protection may require a hypoxia-like response in additional retinal cell types and/or the differential regulation of additional mechanisms.
Investigative ophthalmology & visual science 03/2011; 52(8):5872-80. · 3.43 Impact Factor
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ABSTRACT: Cone photoreceptors mediate visual acuity under daylight conditions, so loss of cone-mediated central vision of course dramatically affects the quality of life of patients suffering from retinal degeneration. Therefore, promoting cone survival has become the goal of many ocular therapies and defining the stage of degeneration that still allows cell rescue is of prime importance. Using the Rpe65(R91W/R91W) mouse, which carries a mutation in the Rpe65 gene leading to progressive photoreceptor degeneration in both patients and mice, we defined stages of retinal degeneration that still allow cone rescue. We evaluated the therapeutic window within which cones can be rescued, using a subretinal injection of a lentiviral vector driving expression of RPE65 in the Rpe65(R91W/R91W) mice. Surprisingly, when applied to adult mice (1 month) this treatment not only stalls or slows cone degeneration but, actually, induces cone-specific protein expression that was previously absent. Before the intervention only part of the cones (40% of the number found in wild-type animals) in the Rpe65(R91W/R91W) mice expressed cone transducin (GNAT2); this fraction increased to 64% after treatment. Correct S-opsin localization is also recovered in the transduced region. In consequence these results represent an extended therapeutic window compared to the Rpe65(-/-) mice, implying that patients suffering from missense mutations might also benefit from a prolonged therapeutic window. Moreover, cones are not only rescued during the course of the degeneration, but can actually recover their initial status, meaning that a proportion of altered cones in chromophore deficiency-related disease can be rehabilitated even though they are severely affected.
PLoS ONE 01/2011; 6(2):e16588. · 4.09 Impact Factor
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ABSTRACT: HIF1A is one of the major transcription factors that regulate tissue response to low oxygen tension. It controls expression of a large number of genes involved in cell survival, proliferation, angiogenesis, and other cellular processes. HIF1A is present at increased levels in the early postnatal retina. In this study its potential function during postnatal development of the mouse retina and retinal vasculature was analyzed.
A mouse line was generated with a Cre-mediated Hif1a knockdown in the peripheral retina. Retinal morphology and vasculature were analyzed in sections and flat mount preparations. Gene and protein expression were determined by real-time PCR and Western blot analysis.
The Cre-mediated knockdown caused a significant reduction in Hif1a gene expression and HIF1A protein levels in the early postnatal retina. Retinal morphology was normal but the Hif1a knockdown prevented the formation of the intermediate vascular plexus in the peripheral retina. The primary plexus and the outer plexus were less affected. The Hif1a knockdown did not affect expression of such angiogenesis-related genes as vascular endothelial growth factor (Vegf) but strongly induced expression of erythropoietin (Epo). At the protein level, EPAS1 (HIF2A) was stabilized in the Hif1a knockdown mice.
The results suggest that HIF1A may be directly or indirectly required for normal development of the retinal vasculature, especially of the intermediate plexus. EPO but not VEGF may play a significant role in the development of this phenotype. HIF1A may not be the main factor that regulates Vegf expression during retinal development in the mouse.
Investigative ophthalmology & visual science 01/2011; 52(5):2109-17. · 3.43 Impact Factor
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ABSTRACT: Loss of vision and blindness in human patients is often caused by the degeneration of neuronal cells in the retina. In mouse models, photoreceptors can be protected from death by hypoxic preconditioning. Preconditioning in low oxygen stabilizes and activates hypoxia inducible transcription factors (HIFs), which play a major role in the hypoxic response of tissues including the retina. We show that a tissue-specific knockdown of von Hippel-Lindau protein (VHL) activated HIF transcription factors in normoxic conditions in the retina. Sustained activation of HIF1 and HIF2 was accompanied by persisting embryonic vasculatures in the posterior eye and the iris. Embryonic vessels persisted into adulthood and led to a severely abnormal mature vessel system with vessels penetrating the photoreceptor layer in adult mice. The sustained hypoxia-like response also activated the leukemia inhibitory factor (LIF)-controlled endogenous molecular cell survival pathway. However, this was not sufficient to protect the retina against massive cell death in all retinal layers of adult mice. Caspases 1, 3 and 8 were upregulated during the degeneration as were several VHL target genes connected to the extracellular matrix. Misregulation of these genes may influence retinal structure and may therefore facilitate growth of vessels into the photoreceptor layer. Thus, an early and sustained activation of a hypoxia-like response in retinal cells leads to abnormal vasculature and severe retinal degeneration in the adult mouse retina.
Neurobiology of Disease 01/2011; 41(1):119-30. · 5.40 Impact Factor
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ABSTRACT: Retinal degeneration causes the induction of a leukemia inhibitory factor (LIF)-controlled survival pathway which includes Janus kinase/signal transducer and activator of transcription signaling. Lack of LIF prevents activation of this signaling cascade and accelerates disease progression leading to a fast loss of photoreceptor cells. In this study, we show that expression of Janus kinase 3 (Jak3), but not of the other members of the family of Janus kinases, is induced in four different models of retinal degeneration and that LIF is essential and sufficient to activate Jak3 gene expression. We also show that the induction of Jak3 and Lif may not depend directly on cell death but rather on the retinal stress during photoreceptor degeneration. However, despite its dependence on LIF, JAK3 is not essential for LIF-mediated photoreceptor protection or gene expression. Also, absence of JAK3 in knockout mice did not affect immune-related responses in the degenerating retina. JAK3 may therefore play a different, yet unknown, role in the retinal response to photoreceptor injury.
Journal of Neurochemistry 03/2010; 113(5):1210-20. · 4.06 Impact Factor
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ABSTRACT: Retinal degeneration is often used to describe a category of human eye diseases, which are characterized by photoreceptor
loss leading to severe visual impairment and blindness. An important, yet heterogeneous group of such diseases is called Retinitis
Pigmentosa (RP). To understand the molecular mechanisms of disease induction and progression and to develop therapeutical
strategies for the preservation of vision in RP patients, appropriate animal models are used in many research laboratories
worldwide. The largest category of models consists of mutant (spontaneous and genetically engineered) mice. However, in recent
years, zebrafish has been established as a highly valuable tool for the study of various biological problems, including retinal
degeneration. In this review, we summarize the currently available mouse and zebrafish models to study retinal degeneration
and give a short overview about recent developments in the field.
Key wordsMouse models-Zebrafish-Retinal degeneration-Retinitis Pigmentosa
12/2009: pages 51-79;
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ABSTRACT: Hypoxic preconditioning stabilizes hypoxia-inducible factor (HIF) 1 alpha in the retina and protects photoreceptors against light-induced cell death. HIF-1 alpha is one of the major transcription factors responding to low oxygen tension and can differentially regulate a large number of target genes. To analyse whether photoreceptor-specific expression of HIF-1 alpha is essential to protect photoreceptors by hypoxic preconditioning, we knocked down expression of HIF-1 alpha specifically in photoreceptor cells, using the cyclization recombinase (Cre)-lox system. The Cre-mediated knockdown caused a 20-fold reduced expression of Hif-1 alpha in the photoreceptor cell layer. In the total retina, RNA expression was reduced by 65%, and hypoxic preconditioning led to only a small increase in HIF-1 alpha protein levels. Accordingly, HIF-1 target gene expression after hypoxia was significantly diminished. Retinas of Hif-1 alpha knockdown animals did not show any pathological alterations, and tolerated hypoxic exposure in a comparable way to wild-type retinas. Importantly, the strong neuroprotective effect of hypoxic preconditioning against light-induced photoreceptor degeneration persisted in knockdown mice, suggesting that hypoxia-mediated survival of light exposure does not depend on an autocrine action of HIF-1 alpha in photoreceptor cells. Hypoxia-mediated stabilization of HIF-2 alpha and phosphorylation of signal transducer and activator of transcription 3 (STAT 3) were not affected in the retinas of Hif-1 alpha knockdown mice. Thus, these factors are candidates for regulating the resistance of photoreceptors to light damage after hypoxic preconditioning, along with several potentially neuroprotective genes that were similarly induced in hypoxic knockdown and control mice.
European Journal of Neuroscience 07/2009; 29(12):2291-302. · 3.63 Impact Factor
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Sandrine Joly,
Mike Francke,
Elke Ulbricht,
Susanne Beck,
Matthias Seeliger,
Petra Hirrlinger,
Johannes Hirrlinger,
Karl S Lang,
Martin Zinkernagel,
Bernhard Odermatt, Marijana Samardzija,
Andreas Reichenbach,
Christian Grimm,
Charlotte E Remé
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ABSTRACT: Phagocytosis is essential for the removal of photoreceptor debris following retinal injury. We used two mouse models, mice injected with green fluorescent protein-labeled bone marrow cells or green fluorescent protein-labeled microglia, to study the origin and activation patterns of phagocytic cells after acute blue light-induced retinal lesions. We show that following injury, blood-borne macrophages enter the eye via the optic nerve and ciliary body and soon migrate into the injured retinal area. Resident microglia are also activated rapidly throughout the entire retina and adopt macrophage characteristics only in the injured region. Both blood-borne- and microglia-derived macrophages were involved in the phagocytosis of dead photoreceptors. No obvious breakdown of the blood-retinal barrier was observed. Ccl4, Ccl12, Tgfb1, Csf1, and Tnf were differentially expressed in both the isolated retina and the eyecup of wild-type mice. Debris-laden macrophages appeared to leave the retina into the general circulation, suggesting their potential to become antigen-presenting cells. These experiments provide evidence that both local and immigrant macrophages remove apoptotic photoreceptors and cell debris in the injured retina.
American Journal Of Pathology 06/2009; 174(6):2310-23. · 4.89 Impact Factor
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Marijana Samardzija,
Naoyuki Tanimoto,
Corinne Kostic,
Susanne Beck,
Vitus Oberhauser,
Sandrine Joly,
Markus Thiersch,
Edda Fahl,
Yvan Arsenijevic,
Johannes von Lintig,
Andreas Wenzel,
Mathias W Seeliger,
Christian Grimm
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ABSTRACT: RPE65 is a retinoid isomerase required for the production of 11-cis-retinal, the chromophore of both cone and rod visual pigments. We recently established an R91W knock-in mouse strain as homologous animal model for patients afflicted by this mutation in RPE65. These mice have impaired vision and can only synthesize minute amounts of 11-cis-retinal. Here, we investigated the consequences of this chromophore insufficiency on cone function and pathophysiology. We found that the R91W mutation caused cone opsin mislocalization and progressive geographic cone atrophy. Remnant visual function was mostly mediated by rods. Ablation of rod opsin corrected the localization of cone opsin and improved cone retinal function. Thus, our analyses indicate that under conditions of limited chromophore supply rods and cones compete for 11-cis-retinal that derives from regeneration pathway(s) which are reliant on RPE65. Due to their higher number and the instability of cone opsin, rods are privileged under this condition while cones suffer chromophore deficiency and degenerate. These findings reinforce the notion that in patients any effective gene therapy with RPE65 needs to target the cone-rich macula directly to locally restore the cones' chromophore supply outside the reach of rods.
Human Molecular Genetics 02/2009; 18(7):1266-75. · 7.64 Impact Factor
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ABSTRACT: Expression of leukemia inhibitory factor (LIF) by a subset of Müller glia cells has recently been implicated in an endogenous survival response to photoreceptor injury in a model of inherited retinal degeneration. To investigate whether such a LIF-controlled survival pathway might be commonly induced upon photoreceptor injury independently of the nature of the toxic stimulus, we analyzed the role of LIF during light-induced retinal degeneration.
Lif(+/-) and Lif(-/-) mice were exposed to 15,000 lx of white light for 2 h. Retinal morphology and rhodopsin content were analyzed nine days after light exposure. Gene expression studies were done using real-time PCR. Protein levels were determined by western blotting using specific antibodies.
A lack of LIF reduced survival of photoreceptor cells after light exposure. In the absence of LIF several genes encoding molecules involved in the Janus kinase/signal transducer and activator of transcription (Jak/STAT) signaling pathway were not activated after light exposure. Presence or absence of LIF did not affect AKT (also known as protein kinase B, PKB) signaling and had only a mild effect on extracellular regulated kinase (ERK) phosphorylation. Stress-induced glial fibrillary acidic protein (GFAP) induction was minimal in the absence of LIF.
Our results suggest that increased retinal expression of LIF is a general response to photoreceptor injury. Independent of the nature of the toxic insult (gene mutation, light), LIF may activate an endogenous rescue pathway that protects viable photoreceptor cells, leading to an increased photoreceptor survival in the stressed retina. This defense system may depend on the Jak/STAT pathway and may involve endothelin 2 (EDN2) but not (or only minimally) AKT and ERK1,2 signaling.
Molecular vision 02/2009; 15:1631-7. · 2.20 Impact Factor
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ABSTRACT: Survival and death of photoreceptors in degenerative diseases of the retina is controlled by a multitude of genes and endogenous factors. Some genes may be involved in the degenerative process itself whereas others may be part of an endogenous defense system. We show in two models of retinal degeneration that photoreceptor death strongly induces expression of leukemia inhibitory factor (LIF) in a subset of Muller glia cells in the inner nuclear layer of the retina. LIF expression is essential to induce an extensive intraretinal signaling system which includes Muller cells and photoreceptors and is characterized by an upregulation of Edn2, STAT3, FGF2 and GFAP. In the absence of LIF, Muller cells remain quiescent, the signaling system is not activated and retinal degeneration is strongly accelerated. Intravitreal application of recombinant LIF induces the full molecular pathway including the activation of Muller cells in wild-type and Lif(-/-) mice. Interruption of the signaling cascade by an Edn2 receptor antagonist increases whereas activation of the receptor decreases photoreceptor cell death. Thus, LIF is essential and sufficient to activate an extensive molecular defense response to photoreceptor injury. Our data establish LIF as a Muller cell derived neuronal survival factor which controls an intrinsic protective mechanism that includes Edn2 signaling to support photoreceptor cell survival and to preserve vision in the injured retina.
Journal of Neuroscience 01/2009; 28(51):13765-74. · 7.11 Impact Factor
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ABSTRACT: During light-induced photoreceptor degeneration, large amounts of cellular debris are formed that must be cleared from the subretinal space. The integrins alphavbeta5 and alphavbeta3 are involved in the normal physiological process of phagocytosis in the retina. This study was conducted to investigate the question of whether the lack of beta5 and/or beta3 integrin subunits might influence the course of retinal degeneration and/or clearance of photoreceptor debris induced by acute exposure to light.
Wild-type, beta5(-/-) and beta3(-/-) single-knockout, and beta3(-/-)/beta5(-/-) Ccl2(-/-)/beta5(-/-) double-knockout mice were exposed to 13,000 lux of white light for 2 hours to induce severe photoreceptor degeneration. Real-time PCR and Western blot analysis were used to analyze gene and protein expression, light- and electron microscopy to judge retinal morphology, and immunofluorescence to study retinal distribution of proteins.
Individual or combined deletion of beta3 and beta5 integrin subunits did not affect the pattern of photoreceptor cell loss or the clearance of photoreceptor debris in mice compared with that in wild-type mice. Invading macrophages may contribute to efficient phagocytosis. However, ablation of the MCP-1 gene did not prevent macrophage recruitment. Several chemokines in addition to MCP-1 were induced after light-induced damage that may have compensated for the deletion of MCP-1.
Acute clearance of a large amount of cellular debris from the subretinal space involves invading macrophages and does not depend on beta3 and beta5 integrins.
Investigative ophthalmology & visual science 12/2008; 50(3):1423-32. · 3.43 Impact Factor
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ABSTRACT: Retinal degeneration is a main cause of blindness in humans. Neuroprotective therapies may be used to rescue retinal cells and preserve vision. Hypoxic preconditioning stabilizes the transcription factor HIF-1alpha in the retina and strongly protects photoreceptors in an animal model of light-induced retinal degeneration. To address the molecular mechanisms of the protection, we analyzed the transcriptome of the hypoxic retina using microarrays and real-time PCR.
Hypoxic exposure induced a marked alteration in the retinal transcriptome with significantly different expression levels of 431 genes immediately after hypoxic exposure. The normal expression profile was restored within 16 hours of reoxygenation. Among the differentially regulated genes, several candidates for neuroprotection were identified like metallothionein-1 and -2, the HIF-1 target gene adrenomedullin and the gene encoding the antioxidative and cytoprotective enzyme paraoxonase 1 which was previously not known to be a hypoxia responsive gene in the retina. The strongly upregulated cyclin dependent kinase inhibitor p21 was excluded from being essential for neuroprotection.
Our data suggest that neuroprotection after hypoxic preconditioning is the result of the differential expression of a multitude of genes which may act in concert to protect visual cells against a toxic insult.
BMC Genomics 02/2008; 9:73. · 4.07 Impact Factor
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ABSTRACT: RPE65 is a retinal pigment epithelial protein essential for the regeneration of 11-cis-retinal, the chromophore of cone and rod visual pigments. Mutations in RPE65 lead to a spectrum of retinal dystrophies ranging from Leber's congenital amaurosis to autosomal recessive retinitis pigmentosa. One of the most frequent missense mutations is an amino acid substitution at position 91 (R91W). Affected patients have useful cone vision in the first decade of life, but progressively lose sight during adolescence. We generated R91W knock-in mice to understand the mechanism of retinal degeneration caused by this aberrant Rpe65 variant. We found that in contrast to Rpe65 null mice, low but substantial levels of both RPE65 and 11-cis-retinal were present. Whereas rod function was impaired already in young animals, cone function was less affected. Rhodopsin metabolism and photoreceptor morphology were disturbed, leading to a progressive loss of photoreceptor cells and retinal function. Thus, the consequences of the R91W mutation are clearly distinguishable from an Rpe65 null mutation as evidenced by the production of 11-cis-retinal and rhodopsin as well as by less severe morphological and functional disturbances at early age. Taken together, the pathology in R91W knock-in mice mimics many aspects of the corresponding human blinding disease. Therefore, this mouse mutant provides a valuable animal model to test therapeutic concepts for patients affected by RPE65 missense mutations.
Human Molecular Genetics 02/2008; 17(2):281-92. · 7.64 Impact Factor
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Advances in experimental medicine and biology 02/2008; 613:75-85. · 1.09 Impact Factor
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ABSTRACT: Caspase-1 gene expression has been reported to be upregulated during light-induced retinal degeneration and to be reduced after neuroprotective treatments. Thus, caspase-1 may be proapoptotic in the retina. To test directly the role of caspase-1 in photoreceptor apoptosis, three mouse models were analyzed for retinal degeneration in the presence or absence of caspase-1.
Photoreceptor apoptosis was monitored in one model of induced (exposure to light) and in two models of inherited (rd1, VPP) retinal degeneration. Retinal degeneration was assessed qualitatively by light microscopy and quantitatively by the determination of free nucleosomes with ELISA or by rhodopsin measurements. Gene expression and protein levels were assessed by real-time RT-PCR and by Western blot analysis, respectively.
Levels of caspase-1 proenzyme increased in all models of retinal degeneration concomitantly with the onset of cell death. Maturation or classic activity of caspase-1 was not detected in the retina. Ablation of caspase-1 was protective in the model of adRP (VPP mouse), but not in the two other models. Ablation of interleukin-1 receptor type 1 was without effect. Expression of monocyte chemoattractant protein (MCP)-1 increased in the model protected by caspase-1 ablation.
Increased retinal expression of caspase-1 proenzyme may be a common marker for photoreceptor degeneration. The differential effects of caspase-1 ablation suggests a modulatory role of caspase-1 for photoreceptor apoptosis in some but not all models. Such a modulatory activity may involve a caspase-1 function different from the classic activation of interleukin-1beta.
Investigative Ophthalmology & Visual Science 01/2007; 47(12):5181-90. · 3.60 Impact Factor
