Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions

A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.

Overexpressing NeuroD1 reprograms Müller cells into various types of retinal neurons

The onset of retinal degenerative disease is often associated with neuronal loss. Therefore, how to regenerate new neurons to restore vision is an important issue. NeuroD1 is a neural transcription factor with the ability to reprogram brain astrocytes into neurons in vivo. Here, we demonstrate that in adult mice, NeuroD1 can reprogram Müller cells, the principal glial cell type in the retina, to become retinal neurons. Most strikingly, ectopic expression of NeuroD1 using two different viral vectors converted Müller cells into different cell types. Specifically, AAV7 m8 GFAP681::GFP-ND1 converted Müller cells into inner retinal neurons, including amacrine cells and ganglion cells. In contrast, AAV9 GFAP104::ND1-GFP converted Müller cells into outer retinal neurons such as photoreceptors and horizontal cells, with higher conversion efficiency. Furthermore, we demonstrate that Müller cell conversion induced by AAV9 GFAP104::ND1-GFP displayed clear dose-and time-dependence. These results indicate that Müller cells in adult mice are highly plastic and can be reprogrammed into various subtypes of retinal neurons.

Investigating Müller glia reprogramming in mice: a retrospective of the last decade, and a look to the future

Müller glia,as prominent glial cells within the retina,plays a significant role in maintaining retinal homeostasis in both healthy and diseased states.In lower vertebrates like zebrafish,these cells assume responsibility for spontaneous retinal regeneration,wherein endogenous Müller glia undergo proliferation,transform into Müller glia-derived progenitor cells,and subsequently regenerate the entire retina with restored functionality.Conversely,Müller glia in the mouse and human retina exhibit limited neural reprogramming.Müller glia reprogramming is thus a promising strategy for treating neurodegenerative ocular disorders.Müller glia reprogramming in mice has been accomplished with remarkable success,through various technologies.Advancements in molecular,genetic,epigenetic,morphological,and physiological evaluations have made it easier to document and investigate the Müller glia programming process in mice.Nevertheless,there remain issues that hinder improving reprogramming efficiency and maturity.Thus,understanding the reprogramming mechanism is crucial toward exploring factors that will improve Müller glia reprogramming efficiency,and for developing novel Müller glia reprogramming strategies.This review describes recent progress in relatively successful Müller glia reprogramming strategies.It also provides a basis for developing new Müller glia reprogramming strategies in mice,including epigenetic remodeling,metabolic modulation,immune regulation,chemical small-molecules regulation,extracellular matrix remodeling,and cell-cell fusion,to achieve Müller glia reprogramming in mice.

Neural and Müller glial adaptation of the retina to photoreceptor degeneration

The majority of inherited retinal degenerative diseases and dry age-related macular degeneration are characterized by decay of the outer retina and photoreceptors,which leads to progressive loss of vision.The inner retina,including second-and third-order retinal neurons,also shows aberrant structural changes at all stages of degeneration.Müller glia,the major glial cells maintain retinal homeostasis,activating and rearranging immediately in response to photoreceptor stress.These phenomena are collectively known as retinal remodeling and are anatomically well described,but their impact on visual function is less well characterized.Retinal remodeling has traditionally been considered a detrimental chain of events that decreases visual function.However,emerging evidence from functional assays suggests that remodeling could also be a part of a survival mechanism wherein the inner retina responds plastically to outer retinal degeneration.The visual system’s first synapses between the photoreceptors and bipolar cells undergo rewiring and functionally compensate to maintain normal signal output to the brain.Distinct classes of retinal ganglion cells remain even after the massive loss of photoreceptors.Müller glia possess the regenerative potential for retinal recovery and possibly exert adaptive transcriptional changes in response to neuronal loss.These types of homeostatic changes could potentially explain the well-maintained visual function observed in patients with inherited retinal degenerative diseases who display prominent anatomic retinal pathology.This review will focus on our current understanding of retinal neuronal and Müller glial adaptation for the potential preservation of retinal activity during photoreceptor degeneration.Targeting retinal self-compensatory responses could help generate universal strategies to delay sensory disease progression.

Modulation of TGFβ_2 and dopamine by PKC in retinal Müller cells of guinea pig myopic eye

AIM: To investigate the effect of protein kinase C (PKC) on transforming growth factor-β2 (TGFβ2) and dopamine in retinal Müller cells of guinea pig myopic eye. METHODS: Myopia was induced by translucent goggles in guinea pig, whose retinal Müller cells were cultured using the enzyme-digesting method. Retinal Müller cells were divided into 5 groups: normal control, myopia, myopia plus GF109203X, myopia plus PMA, myopia plus DMSO. PKC activities were detected by the non-radioactive methods. TGFβ2 and tyrosine hydroxylase (TH) proteins were analyzed by Western Blotting in retinal Müller cells. Dopamine was determined by the high-performance liquid chromatography- electrochemical detection in suspensions. RESULTS: After 14 days deprived, the occluded eyes became myopic with ocular axle elongating. Müller cells of guinea pigs were obtained using enzyme digestion. Compared with normal control group, the increase in PKC activity and the up-regulation in TGFβ2 expression were found in retinal Müller cells of myopic eyes, with the decrease of TH and dopamine content (P <0.05). After PKC activated by PMA, TGFβ2 and TH content were up-regulated with the increase of dopamine content (P <0.05). While the PKC activities was inhibited by GF109203X, proteins of TGFβ2 and TH were down-regulated in the myopic eyes, with the decrease of dopamine content (P <0.05). CONCLUSION: TGFβ2 and dopamine are modulated by PKC in Müller cells of the myopic eyes in guinea pig.

Pirfenidone suppresses the abnormal activation of human Müller cells after platelet-derived growth factor-BB stimulation

AIM: To determine the effect of pirfenidone on the activated human Müller cells by platelet-derived growth factor-BB(PDGF-BB). METHODS: The primary human Müller cells were separated from retinal tissues and established the pathogenic model by stimulated with PDGF-BB. The Müller cells behaviour of normal group and the model group was measured by MTT assay, Trypan blue assay, cell migration assay, and collagen contraction assay. The expression of transforming growth factor(TGF)-β1,-β2, and pigment epithelium-derived factor(PEDF) was estimated with realtime polymerase chain reaction(PCR), Western blot and immunofluorescence analyses. RESULTS: A pathogenic/proliferative model of Müller cells was established by stimulating normal cultured Müller cells with 10 ng/mL PDGF-BB for 48 h. After treated with 0.2 and 0.3 mg/mL pirfenidone, the proliferation, migration and collagen contraction was statistically significantly depressed in the model group compared with the normal groups. The expression levels of TGF-β1 and TGF-β2 were significantly down-regulated, while the PEDF expression was significantly up-regulated after treated with 0.2 and 0.3 mg/mL pirfenidone in the model group. CONCLUSION: Pirfenidone effectively suppress the proliferation, migration and collagen contraction of the human Müller cells stimulated with PDGF-BB through down-regulation of TGF-β1/TGF-β2 and up-regulation of PEDF.

Enrichment of retinal ganglion and Müller glia progenitors from retinal organoids derived from human induced pluripotent stem cells-possibilities and current limitations

BACKGROUND Retinal organoids serve as excellent human-specific disease models for conditions affecting otherwise inaccessible retinal tissue from patients.They permit the isolation of key cell types affected in various eye diseases including retinal ganglion cells(RGCs)and Müller glia.AIM To refine human-induced pluripotent stem cells(hiPSCs)differentiated into threedimensional(3D)retinal organoids to generate sufficient numbers of RGCs and Müller glia progenitors for downstream analyses.METHODS In this study we described,evaluated,and refined methods with which to generate Müller glia and RGC progenitors,isolated them via magnetic-activated cell sorting,and assessed their lineage stability after prolonged 2D culture.Putative progenitor populations were characterized via quantitative PCR and immunocytochemistry,and the ultrastructural composition of retinal organoid cells was investigated.RESULTS Our study confirms the feasibility of generating marker-characterized Müller glia and RGC progenitors within retinal organoids.Such retinal organoids can be dissociated and the Müller glia and RGC progenitor-like cells isolated via magnetic-activated cell sorting and propagated as monolayers.CONCLUSION Enrichment of Müller glia and RGC progenitors from retinal organoids is a feasible method with which to study cell type-specific disease phenotypes and to potentially generate specific retinal populations for cell replacement therapies.

The ROCK pathway inhibitor Y-27632 mitigates hypoxia and oxidative stress-induced injury to retinal Müller cells

Rho kinase （ROCK） was the first downstream Rho effector found to mediate RhoA-induced actin cytoskeletal changes through effects on myosin light chain phosphorylation. There is abundant evidence that the ROCK pathway participates in the pathogenesis of retinal endothelial injury and proliferative epiretinal membrane traction. In this study, we investigated the effect of the ROCK pathway inhibitor Y-27632 on retinal Müller cells subjected to hypoxia or oxidative stress. Müller cells were subjected to hypoxia or oxidative stress by exposure to CoCl2 or H2O2. After a 24-hour treatment with Y-27632, the 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide assay was used to assess the survival of Müller cells. Hoechst 33258 was used to detect apoptosis, while 2′,7′-dichlorodihydrofluorescein diacetate was used to measure reactive oxygen species generation. A transwell chamber system was used to examine the migration ability of Müller cells. Western blot assay was used to detect the expression levels of α-smooth muscle actin, glutamine synthetase and vimentin. After treatment with Y-27632, Müller cells subjected to hypoxia or oxidative stress exhibited a morphology similar to control cells. Y-27632 reduced apoptosis, α-smooth muscle actin expression and reactive oxygen species generation under oxidative stress, and it reduced cell migration under hypoxia. Y-27632 also upregulated glutamine synthetase expression under hypoxia but did not impact vimentin expression. These findings suggest that Y-27632 protects Müller cells against cellular injury caused by oxidative stress and hypoxia by inhibiting the ROCK pathway.

pigment epithelium-derived factor protects the morphological structure of retinal Müller cells in diabetic rats

AIM: To investigate if pigment epithelium-derived factor(PEDF) has any protective effect on the retinal Müller cells of Sprague-Dawley rats suffering from diabetes mellitus.METHODS: Sixty Sprague-Dawley rats were randomly divided into a negative control group, a group receiving0.1 μg/μL PEDF, another group receiving 0.2 μg/μL PEDF,and a group receiving balanced salt solution(BSS). Rats in both the PEDF and BSS groups were treated intravitreally based on previously established diabetic models. After 4wk of treatment, morphological alterations of Müller cells and protein expression of glutamine synthase(GS) and glial fibrillary acidic protein(GFAP)were analyzed.RESULTS:PEDFateither0.1μg/μLor0.2μg/μLsignificantly improved the structures of both nuclei and organelles of Müller cells compared to the BSS-treated group.Expression of GS was significantly higher in the 0.2 μg/μL PEDF group than that in the BSS group(P =0.012), but expression of GFAP was significantly lower in the 0.2 μg/μL PEDF group than that in the BSS group(P =0.000);however, there were no significant differences in expression of these proteins between the 0.1 μg/μL PEDF group and the BSS group(P =0.608, P =0.152). CONCLUSION: PEDF protects the morphological ultrastructure of Müller cells, improves the expression of glutamate synthase and prevents cell gliosis.

Effect of taurine on GFAP and TauT expressions in rat retinal Müller cells in high glucose culture

Objective： To detect the expression of glial fibrillary acid protein （GFAP） and taurine transporter （TauT） in the retinal Müller cells in high glucose culture with taurine and to explore the influence of glucose on the taurine transporting, and the possible protective effects of taurine on MUller cells in early diabetic retinopathy. Methods： The Müller cells from the rat retina were cultured in high glucose, and GFAP and Taut expressions were detected in the cells treated with different doses of taurine by immuocytochemical fluorescein staining and Western blotting. Results： High glucose enhanced the expression of GFAP and decreased the expression of TauT in Müller cells. Taurine decreased the up-regulation of GFAP in the cells which was induced by high glucose; 0. 1-10 mmol/L taurine increased the expression of TauT in Müller cells. Conclusion： Taurine can inhibit the changes in Müller cell resulted from high glucose.

Effects of 530 nm monochromatic light on basic fibroblast growth factor and transforming growth factor-β1 expression in Müller cells

AIMTo expose rat retinal M&#x000fc;ller cells to 530 nm monochromatic light and investigate the influence of varying light illumination times on basic fibroblast growth factor (bFGF) and transforming growth factor-&#x003b2;1 (TGF-&#x003b2;1) expression.METHODSThree groups of rat retinal M&#x000fc;ller cells cultured in vitro under a 530 nm monochromatic light were divided into 6, 12 and 24h experimental groups, while cells incubated under dark conditions served as the control group. The bFGF and TGF-&#x003b2;1 mRNA expression, protein levels and fluorescence intensity of the M&#x000fc;ller cells were analyzed.RESULTSThe bFGF mRNA expression and protein levels were significantly upregulated in M&#x000fc;ller cells in all three experimental groups compared with the control group (P&#x0003c;0.05), while that of TGF-&#x003b2;1 was downregulated (P&#x0003c;0.05). Also, bFGF expression was positively correlated, but TGF-&#x003b2;1 expression was negatively correlated with illumination time. The largest changes for both cytokines were seen in the 24h group. The changes in bFGF and TGF-&#x003b2;1 fluorescence intensity were highest in the 24h group, and significant differences were observed among the experimental groups (P&#x0003c;0.05).CONCLUSIONThe expressions of bFGF and TGF-&#x003b2;1 changed in a time-dependent manner in M&#x000fc;ller cells exposed to 530 nm monochromatic light with 250 lx illumination intensity. M&#x000fc;ller cells might play a role in the development of myopia by increasing bFGF expression or decreasing TGF-&#x003b2;1 expression. Changes in cytokine expression in retinal M&#x000fc;ller cells may affect monochromatic light-induced myopia.

Potential role of Müller cells in the pathogenesis of macropsia associated with epiretinal membrane:a hypothesis revisited

Pathophysiological explanations for metamorphopsia associated with retinal pathologies generally focus on photoreceptor organization disruption. However, the retinal microarchitecture is complicated, and we hypothesize that other retinal cells may also be involved. Metamorphopsia has been widely studied in eyes with epiretinal membranes and we revisit the idea that Müller cell displacement causes retinal macropsia. A Pub Med query and related article search for the macula ultrastructure under normal and pathological conditions revealed an enormous amount of information, particularly ultrahigh definition optical coherence tomography and other retinal imaging modality studies. Findings of these imaging studies support our hypothesis that Müller cells, and not cone photoreceptors, are primarily responsible for macropsia in eyes with epiretinal membranes. More specifically, we conclude that displacement of Müller cell endfeet, and not photoreceptor cones, is a more likely the explanation for retinal macropsia associated with epiretinal membranes.

Absence of ephrin-A2/A3 increases retinal regenerative potential for Müller cells in Rhodopsin knockout mice

Müller cells(MC) are considered dormant retinal progenitor cells in mammals.Previous studies demonstrated ephrin-As act as negative regulators of neural progenitor cells in the retina and brain.It remains unclear whether the lack of ephrin-A2/A3 is sufficient to promote the neurogenic potential of MC.Here we investigated whether the MC is the primary retinal cell type expressing ephrin-A2/A3 and their role on the neurogenic potential of Müller cells.In this study, we showed that ephrin-A2/A3 and their receptor EphA4 were expressed in retina and especially enriched in MC.The level of ephrin As/EphA4 expression increased as the retina matured that is correlated with the reduced proliferative and progenitor cell potential of MC.Next, we investigated the proliferation in primary MC cultures isolated from wild-type and A2~(–/–) A3~(–/–) mice by 5-ethynyl-2′-deoxyuridine(EdU) incorporation.We detected a significant increase of EdU~+ cells in MC derived from A2~(–/–) A3~(–/–) mice.Next, we investigated the role of ephrin-A2/A3 in mice undergoing photoreceptor degeneration such as Rhodopsin knockout(Rho~(–/–)) mice.To further evaluate the role of ephrin-A2/A3 in MC proliferation in vivo, EdU was injected intraperitoneally to adult wild-type, A2~(–/–) A3~(–/–), Rho~(–/–) and Rho~(–/–) A2~(–/–) A3~(–/–) mice and the numbers of EdU~+ cells distributed among different layers of the retina.Ephrin As/EphA4 expression was upregulated in the retina of Rho~(–/–) mice compared to the wild-type mice.In addition, cultured MC derived from ephrin-A2~(–/–) A3~(–/–) mice also expressed higher levels of progenitor cell markers and exhibited higher proliferation potential than those from wild-type mice.Interestingly, we detected a significant increase of EdU~+ cells in the retinas of adult ephrin-A2~(–/–) A3~(–/–) mice mainly in the inner nuclear layer;and these EdU~+ cells were co-localized with MC marker, cellular retinaldehyde-binding protein, suggesting some proliferating cells are from MC.In Rhodopsin knockout mice(Rho~(–/–) A2~(–/–) A3~(–/–) mice), a significantly greater amount of EdU~+ cells were located in the ciliary body, retina and RPE than that of Rho~(–/–) mice.Comparing between 6 and 12 weeks old Rho~(–/–) A2~(–/–) A3~(–/–) mice, we recorded more EdU~+ cells in the outer nuclear layer in the 12-week-old mice undergoing severe retinal degeneration.Taken together, Ephrin-A2/A3 are negative regulators of the proliferative and neurogenic potentials of MC.Absence of ephrin-A2/A3 promotes the migration of proliferating cells into the outer nuclear layer and may lead to retinal cell regeneration.All experimental procedures were approved by the Animal Care and Use Committee at Schepens Eye Research Institute, USA(approval No.S-353-0715) on October 24, 2012.

Foveal regeneration after resolution of cystoid macular edema without and with internal limiting membrane detachment:presumed role of glial cells for foveal structure stabilization

AIM: To document with spectral-domain optical coherence tomography the morphological regeneration of the fovea after resolution of cystoid macular edema(CME) without and with internal limiting membrane(ILM) detachment and to discuss the presumed role of the glial scaffold for foveal structure stabilization. METHODS: A retrospective case series of 38 eyes of 35 patients is described. Of these, 17 eyes of 16 patients displayed foveal regeneration after resolution of CME, and 6 eyes of 6 patients displayed CME with ILM detachment. Eleven eyes of 9 patients displayed other kinds of foveal and retinal disorders associated with ILM detachment. RESULTS: The pattern of edematous cyst distribution, with or without a large cyst in the foveola and preferred location of cysts in the inner nuclear layer or Henle fiber layer(HFL), may vary between different eyes with CME or in one eye during different CME episodes. Large cysts in the foveola may be associated with a tractional elevation of the inner foveal layers and the formation of a foveoschisis in the HFL. Edematous cysts are usually not formed in the ganglion cell layer. Eyes with CME and ILM detachment display a schisis between the detached ILM and nerve fiber layer(NFL) which is traversed by Müller cell trunks. ILM detachment was also found in single eyes with myopic traction maculopathy, macular pucker, full-thickness macular holes, outer lamellar holes, and glaucomatous parapapillary retinoschisis, and in 3 eyes with Müller cell sheen dystrophy(MCSD). As observed in eyes with MCSD, cellophane maculopathy, and macular pucker, respectively, fundus light reflections can be caused by different highly reflective membranes or layers: the thickened and tightened ILM which may or may not be detached from the NFL, the NFL, or idiopathic epiretinal membranes. In eyes with short single or multiple CME episodes, the central fovea regenerated either completely, which included the disappearance of irregularities of the photoreceptor layer lines and the reformation of a fovea externa, or with remaining irregularities of the photoreceptor layer lines. CONCLUSION: The examples of a complete regeneration of the foveal morphology after transient CME show that the fovea may withstand even large tractional deformations and has a conspicuous capacity of structural regeneration as long as no cell degeneration occurs. It is suggested that the regenerative capacity depends on the integrity of the threedimensional glial scaffold for foveal structure stabilization composed of Müller cell and astrocyte processes. The glial scaffold may also maintain the retinal structure after loss of most retinal neurons as in late-stage MCSD.

Effects of Avastin on Expression of AQP4 in Müller Cells under Hypoxia

The aim of this study was to investigate the effects of Avastin on aquaporin4(AQP4) expression in human retinal Müller cells in vitro under hypoxia,so as to explore the mechanism of Avastin treating retinal edema.The human Müller cells were cultured using the enzymatic digestion method.Müller cells were identified under the transmission electron microscopy and by using immunofluorescence staining.By using semi-quantitative reverse transcription polymerase chain reaction(RT-PCR),the expression of AQP4 mRNA and VEGF mRNA in Müller cells cultured with 500 μmol/L CoCl 2 for 0,3,6,12 and 24 h,and with 0,100,300,500 and 700 μmol/L CoCl 2 for 24 h was detected.The expression of AQP4 mRNA in Müller cells cultured with 50 ng/mL exogenous vascular endothelial growth factor(VEGF) for 0,0.5,1,2 and 4 h,and with 0,25,50 and 75 ng/mL VEGF for 24 h was detected.Amplified cDNA products of AQP4 mRNA in Müller cells cultured with 500 μmol/L CoCl 2 and 200 μg/mL Avastin for 24 h were detected.The results showed that more than 95% cells displayed positive immunofluorescence reaction.Characteristic 8-10 nm intracellular filaments could be seen in the cytoplasm under the transmission electron microscopy.In the CoCl 2 experimental groups,the expression of AQP4 mRNA and VEGF mRNA in Müller cells was increased as compared with the control group.Alteration of AQP4 mRNA and VEGF mRNA levels showed a significantly positive correlation(r 2 =0.822,P<0.05).The expression of AQP4 mRNA in Müller cells was increased by VEGF.The expression of AQP4 mRNA was significantly decreased by Avastin as compared with the control group.It is suggested that Avastin can decrease the expression of AQP4 mRNA in human Müller cells under chemical hypoxic conditions partially via VEGF path,which may be one of the mechanisms of Avastin treating retinal edema.

Neuroprotection of the inner retina:Müller cells and lactate

Müller cells：The neglected neighbor：Müller cells constitute the majority of retinal glial cells and offer more alternating functions than any other cell of the retina.Uniquely,Müller cells cover the complete thickness of the retina,and their roles therefore differ correspondingly to the retinal segment in which they are located.In the inner retina,Müller cells are crucial in taking up toxic molecules,such as excessive.

Neurochemical plasticity of Müller cells after retinal injury: overexpression of GAT-3 may potentiate excitotoxicity

The retina is a multilayered tissue that develops following a central-to-peripheral gradient. Its structure derives from multipotent precursors, as shown through clonal analysis of retinal cell lineage. These progenitors generate diverse cell types, controlled by complex influences of intrinsic and extrinsic factors （Hatakevama and Kagevama, 2004）.

Soxllb regulates the migration and fate determination of Müller glia-derived progenitors during retina regeneration in zebrafish

The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 homolog,regulates the migration and fate determination of Müller glia-derived progenitors(MGPCs)in an adult zebrafish model of mechanical retinal injury.Following a stab injury,the expression of Sox11 b was induced in proliferating MGPCs in the retina.Sox11 b knockdown did not affect MGPC formation at 4 days post-injury,although the nuclear morphology and subsequent radial migration of MGPCs were alte red.At 7 days post-injury,Sox11 b knockdown res ulted in an increased proportion of MGPCs in the inner retina and a decreased propo rtion of MGPCs in the outer nuclear layer,compared with controls.Furthermore,Sox11 b knockdown led to reduced photoreceptor regeneration,while it increased the numbe rs of newborn amacrines and retinal ganglion cells.Finally,quantitative polymerase chain reaction analysis revealed that Sox11 b regulated the expression of Notch signaling components in the retina,and Notch inhibition partially recapitulated the Sox11 b knockdown phenotype,indicating that Notch signaling functions downstream of Sox11 b.Our findings imply that Sox11 b plays key roles in MGPC migration and fate determination during retina regeneration in zebrafish,which may have critical im plications for future explorations of retinal repair in mammals.

Protective effects of curcumin on retinal Müller cell in early diabetic rats

·AIM: To explore the effects and potential mechanisms of curcumin on retinal Müller cell in early diabetic rats. ·METHODS: Diabetic rats were induced by a single intraperitoneal injection of streptozotocin (STZ). Male Sprague-Dawley (SD) rats were randomly assigned into 4 groups: control group (nave SD rats administered with a single intraperitoneal injection of citric buffer), diabetic group (STZ -diabetic rats), dimethyl sulfoxide (DMSO) group (diabetic rats intraperitoneally administered with mixture of DMSO and normal saline, once a day) and curcumin group (diabetic rats intraperitoneally administered with curcumin, 80mg/kg, once a day). Three months after diabetes onset, malondialdehyde (MDA, indication of oxidative stress level) and reduced glutathione (GSH) in retina were detected with kits, glial fibrillary acidic protein (GFAP) in retina was revealed by immunohistochemistry and Western blot, and retinal glutamine synthetase (GS) were observed by Western blot. ·RESULTS: Compared with control group, retinal MDA was increased, and GSH was decreased in diabetic and DMSO groups ( 【0.05, respectively). While, retinal MDA and GSH in curcumin group showed no difference compared with control group ( 】0.05). Furthermore, upregulation of retinal GFAP and down-regulation of retinal GS were detected in diabetic and DMSO groups, and no alteration could be observed in curcumin group revealed with Western blot. Compared with control group, retinal Müller cells showed significant increase in GFAP immunochemistry staining in diabetic and DMSO groups. Moreover, GFAP -positive staining was decreased in curcumin group compared with diabetic group. · CONCLUSION: Curcumin inhibits diabetic retinal oxidative stress, protects Müller cell, and prevents the down -regulation of GS in diabetic retina. Therefore, curcumin has a therapeutic potential in the treatment of diabetic retinopathy (DR).

Role of endoplasmic reticulum stress in the loss of retinal ganglion cells in diabetic retinopathy

Endoplasmic reticulum stress is closely involved in the early stage of diabetic retinopathy. In the present study, a streptozotocin-induced diabetic animal model was given an intraperitoneal injection of tauroursodeoxycholic acid. Results from immunofluorescent co-localization experiments showed that both caspase-12 protein and c-Jun N-terminal kinase 1 phosphorylation levels significantly in- creased, which was associated with retinal ganglion cell death in diabetic retinas. The C/ERB ho- mologous protein pathway directly contributed to glial reactivity, and was subsequently responsible for neuronal loss and vascular abnormalities in diabetic retinopathy. Our experimental findings in- dicate that endoplasmic reticulum stress plays an important role in diabetes-induced retinal neu- ronal loss and vascular abnormalities, and that inhibiting the activation of the endoplasmic reticulum stress pathway provides effective protection against diabetic retinopathy.