Synergistic effect of chitosan and ß-carotene in inhibiting MNU-induced retinitis pigmentosa.

In this study, N-Methyl-N-nitrosourea (MNU) was intraperitoneally injected to construct a mouse retinitis pigmentosa (RP) model to evaluate the protective effect of chitosan and ß-carotene on RP. The results demonstrated that chitosan synergized with ß-carotene significantly reduced retinal histopathological structural damage in RP mice. The co-treatment group of ß-carotene and chitosan restored the retinal thickness and outer nuclear layer thickness better than the group treated with the two alone, and the thickness reached the normal level. The content of ß-carotene and retinoids in the liver of chitosan and ß-carotene co-treated group increased by 46.75 % and 20.69 %, respectively, compared to the ß-carotene group. Chitosan and ß-carotene supplement suppressed the expressions of Bax, Calpain2, Caspase3, NF-κB, TNF-α, IL-6, and IL-1ß, and promoted the up-regulation of Bcl2. Chitosan and ß-carotene interventions remarkably contributed to the content of SCFAs and enhanced the abundance of Ruminococcaceae, Rikenellaceae, Odoribacteraceae and Helicobacteraceae. Correlation analysis demonstrated a strong association between gut microbiota and improvement in retinitis pigmentosa. This study will provide a reference for the study of the gut-eye axis.

Dysregulation of Spliceosomes Complex Induces Retinitis Pigmentosa-Like Characteristics in sf3b4-Depleted Zebrafish.

The SF3B4 gene encodes a highly conserved protein that plays a critical role in mRNA splicing. Mutations in this gene are known to cause Nager syndrome, a rare craniofacial disorder. Although SF3B4 expression is detected in the optic vesicle before it is detected in the limb and somite, the role of SF3B4 in the eye is not well understood. This study investigated the function of sf3b4 in the retina by performing transcriptome profiles, immunostaining, and behavioral analysis of sf3b4-/- mutant zebrafish. Results from this study suggest that dysregulation of the spliceosome complex affects not only craniofacial development but also retinogenesis. Zebrafish lacking functional sf3b4 displayed characteristics similar to retinitis pigmentosa (RP), marked by severe retinal pigment epithelium defects and rod degeneration. Pathway analysis revealed altered retinol metabolism and retinoic acid signaling in the sf3b4-/- mutants. Supplementation of retinoic acid rescued key cellular phenotypes observed in the sf3b4-/- mutants, offering potential therapeutic strategies for RP in the future. In conclusion, this study sheds light on the previously unknown role of SF3B4 in retinogenesis and provides insights into the underlying mechanisms of RP.

Bujing Yishi tablets alleviate photoreceptor cells death via the P2X7R/CX3CL1/CX3CR1 pathway in Retinitis Pigmentosa rats.

BACKGROUND: Retinitis pigmentosa (RP) refers to a group of progressive photoreceptor degenerative diseases. The activation of microglia has been reported to play an important role in the photoreceptor degeneration in RP retinal. Bujing Yishi tablets (BJYS), a Chinese herbal medicine, has been used to treat retinal diseases in China with desirable effect in improving visual function. However, the mechanisms underlying the efficacy of BJYS treatment in RP are not yet fully understood. PURPOSE: Based on the preliminary experiments, this study aimed to investigate the therapeutic mechanism involved in treating N-Methyl-N-Nitrosourea (MNU)-induced retinal degeneration of RP with BJYS. METHODS: To explore the efficacy of BJYS, a rat experimental RP model was established through intraperitoneal injection of MNU (50 mg/kg). Two experiment was carried out. After the treatment, we conducted H&E, TUNEL, retinal cytokine levels and IBA-1 expression in microglia to confirm the impact on RP model. The specific mechanism of action of BJYS tablet was assessed by western blot, real-time polymerase chain reaction (RT-PCR), and immunofluorescence to determine the mRNA and protein expression levels involved in clarifying the effectiveness of BJYS exerted through P2X7R/CX3CL1/CX3CR1 pathway. RESULTS: Significant alleviation of retinal morphological structure and photoreceptor degeneration by BJYS treatment was observed in the retinal of MNU-induced RP rats, BJYS prevented the reduction of ONL thickness and decreased the level of apoptotic cells in ONL. It also inhibited microglia overactivation and reduced retinal levels of IL-1ß, IL-6, TNF-α. In addition, BJYS decreased the protein expression and mRNA expression of P2X7, CX3CL1 and CX3CR1 and reduced the phosphorylation of p38 MAPK. CONCLUSION: In summary, this study suggested that BJYS treatment could alleviate photoreceptors degeneration of RP by inhibiting microglia overactivation and inflammation through the P2X7R/CX3CL1/CX3CR1 pathway. These effects suggest that BJYS tablets may serve as a promising oral therapeutic agent for RP.

Protective effect of ZYMT, a traditional Chinese patent medicine in a mouse model of retinitis pigmentosa.

Retinitis pigmentosa (RP) is the most common genetic disorder that causes blindness. At present, there exists no remedy for the disease. The aim of the current research was to investigate the protective effect of Zhangyanming Tablets (ZYMT) in a mouse model of RP, and explore the underlying mechanism. Eighty RP mice were randomly divided into two groups. The mice in ZYMT group were administered with ZYMT suspension(0.0378 g/mL), while the mice in model group were given the same volume of distilled water. At day 7 and day 14 after intervention, electroretinogram (ERG), fundus photography, and histological examination were used to assess the retinal function and structure. TUNEL, immunofluorescence and qPCR were used to evaluate cell apoptosis and expressions of Sirt1, Iba1, Bcl-2, Bax and Caspase-3. A significantly shortened latency of ERG waves was observed in ZYMT-treated mice, in comparison to those in the model group (P < 0.05). Histologically, ultrastructure of the retina was better preserved, and the outer nuclear layer (ONL) exhibited marked increase in thickness and cell count in ZYMP group (P < 0.05). The apoptosis rate was decreased markedly in ZYMT group. Immunofluorescence analysis showed that the expressions of Iba1 and Bcl-2 in the retina were increased, Bax and Caspase-3 were decreased after ZYMT intervention, while the qPCR revealed that the expressions of Iba1 and Sirt1 were significantly increased (P < 0.05). This study indicated that ZYMT has protective effect on retinal function and morphology of inherited RP mice in the early stage, possibly mediated via the regulation of antioxidant and anti-/pro-apoptotic factors expressions.

Cell-specific electrical stimulation of human retinal neurons assessed by pupillary response dynamics in vivo.

Studies on the electrical excitability of retinal neurons show that photoreceptors and other cell types can be selectively activated by distinct stimulation frequencies in vitro. Yet, this principle still needs to be validated in humans in vivo. As a first step, this study explored the frequency preferences of human rods by means of transcorneal electrostimulation (TES), using the electrically-elicited pupillary responses (EEPRs) as an objective readout. The stimulation paradigm contained a 1.2 Hz sinusoidal envelope, which was superimposed on variable carrier frequencies (4-30 Hz). These currents were delivered to one of the participant's eyes via a corneal electrode and consensual pupillary reactions were recorded from the contralateral eye. The responsiveness of the retina at each frequency was assessed based on the EEPR dynamics. Differences between healthy participants and patients with retinitis pigmentosa were evaluated to identify the preferred frequency range of rods. The responsiveness of healthy individuals revealed a clear peak around 6-8 Hz. In contrast, the pupillary responses of patients were significantly reduced in the lower frequency range. These findings suggest that the responses in this frequency bin were selectively mediated by rods. This work provides evidence that different retinal cell types can be selectively activated via TES in vivo, and that this effect can be captured noninvasively using EEPRs. This knowledge may be exploited for the diagnostics and therapy of retinal diseases, e.g., to design cell-specific functional tests for the degenerating retina, or to optimize stimulation paradigms which are currently used by retinal prostheses.

Long-term vitamin A supplementation in a preclinical mouse model for RhoD190N-associated retinitis pigmentosa.

Retinitis pigmentosa (RP) is caused by one of many possible gene mutations. The National Institutes of Health recommends high daily doses of vitamin A palmitate for RP patients. There is a critical knowledge gap surrounding the therapeutic applicability of vitamin A to patients with the different subtypes of the disease. Here, we present a case report of a patient with RP caused by a p.D190N mutation in Rhodopsin (RHO) associated with abnormally high quantitative autofluorescence values after long-term vitamin A supplementation. We investigated the effects of vitamin A treatment strategy on RP caused by the p.D190N mutation in RHO by exposing Rhodopsin p.D190N (RhoD190N/+) and wild-type (WT) mice to experimental vitamin A-supplemented and standard control diets. The patient's case suggests that the vitamin A treatment strategy should be further studied to determine its effect on RP caused by p.D190N mutation in RHO and other mutations. Our mouse experiments revealed that RhoD190N/+ mice on the vitamin A diet exhibited higher levels of autofluorescence and lipofuscin metabolites compared to WT mice on the same diet and isogenic controls on the standard control diet. Vitamin A supplementation diminished photoreceptor function in RhoD190N/+ mice while preserving cone response in WT mice. Our findings highlight the importance of more investigations into the efficacy of clinical treatments like vitamin A for patients with certain genetic subtypes of disease and of genotyping in the precision care of inherited retinal degenerations.

Drug screening with zebrafish visual behavior identifies carvedilol as a potential treatment for an autosomal dominant form of retinitis pigmentosa.

Retinitis Pigmentosa (RP) is a mostly incurable inherited retinal degeneration affecting approximately 1 in 4000 individuals globally. The goal of this work was to identify drugs that can help patients suffering from the disease. To accomplish this, we screened drugs on a zebrafish autosomal dominant RP model. This model expresses a truncated human rhodopsin transgene (Q344X) causing significant rod degeneration by 7 days post-fertilization (dpf). Consequently, the larvae displayed a deficit in visual motor response (VMR) under scotopic condition. The diminished VMR was leveraged to screen an ENZO SCREEN-WELL REDOX library since oxidative stress is postulated to play a role in RP progression. Our screening identified a beta-blocker, carvedilol, that ameliorated the deficient VMR of the RP larvae and increased their rod number. Carvedilol may directly on rods as it affected the adrenergic pathway in the photoreceptor-like human Y79 cell line. Since carvedilol is an FDA-approved drug, our findings suggest that carvedilol can potentially be repurposed to treat autosomal dominant RP patients.

Photobiomodulation preserves mitochondrial redox state and is retinoprotective in a rodent model of retinitis pigmentosa.

Photobiomodulation (PBM) by far-red (FR) to near-infrared (NIR) light has been demonstrated to restore the function of damaged mitochondria, increase the production of cytoprotective factors and prevent cell death. Our laboratory has shown that FR PBM improves functional and structural outcomes in animal models of retinal injury and retinal degenerative disease. The current study tested the hypothesis that a brief course of NIR (830 nm) PBM would preserve mitochondrial metabolic state and attenuate photoreceptor loss in a model of retinitis pigmentosa, the P23H transgenic rat. P23H rat pups were treated with 830 nm light (180 s; 25 mW/cm2; 4.5 J/cm2) using a light-emitting diode array (Quantum Devices, Barneveld, WI) from postnatal day (p) 10 to p25. Sham-treated rats were restrained, but not treated with 830 nm light. Retinal metabolic state, function and morphology were assessed at p30 by measurement of mitochondrial redox (NADH/FAD) state by 3D optical cryo-imaging, electroretinography (ERG), spectral-domain optical coherence tomography (SD-OCT), and histomorphometry. PBM preserved retinal metabolic state, retinal function, and retinal morphology in PBM-treated animals compared to the sham-treated group. PBM protected against the disruption of the oxidation state of the mitochondrial respiratory chain observed in sham-treated animals. Scotopic ERG responses over a range of flash intensities were significantly greater in PBM-treated rats compared to sham controls. SD-OCT studies and histological assessment showed that PBM preserved the structural integrity of the retina. These findings demonstrate for the first time a direct effect of NIR PBM on retinal mitochondrial redox status in a well-established model of retinal disease. They show that chronic proteotoxic stress disrupts retinal bioenergetics resulting in mitochondrial dysfunction, and retinal degeneration and that therapies normalizing mitochondrial metabolism have considerable potential for the treatment of retinal degenerative disease.

Gypenosides attenuate retinal degeneration in a zebrafish retinitis pigmentosa model.

Retinitis pigmentosa (RP) is a collection of heterogenous genetic retinal disorders resulting in cumulative retinal deterioration involving progressive loss of photoreceptors and eventually in total blindness. Oxidative stress plays a central role in this photoreceptor loss. Gypenosides (Gyp) are the main functional component isolated from the climbing vine Gynostemma pentaphyllum and have been shown to defend cells against the effects of oxidative stress and inflammation, providing protection in experimentally-induced optic neuritis. The zebrafish model has been used to investigate a range of human diseases. Previously we reported early retinal degeneration in a mutant zebrafish line carrying a point-nonsense mutation in the retinitis pigmentosa GTPase regulator interacting protein 1 (rpgrip1) gene that is mutated in RP patients. The current study investigated the potential protective effects of Gyp against photoreceptor degeneration in the Rpgrip1 deleted zebrafish. Rpgrip1 mutant zebrafish were treated with 5 µg/ml of Gyp in E3 medium from 6 h post fertilization (hpf) till 1 month post fertilization (mpf). Rpgrip1 mutant zebrafish treated with 5 µg/ml of Gyp showed a significant decrease by 68.41% (p = 0.0002) in photoreceptor cell death compared to that of untreated mutant zebrafish. Expression of antioxidant genes catalase, sod1, sod2, gpx1, gclm, nqo-1 and nrf-2 was significantly decreased in rpgrip1 mutant zebrafish eyes by 61.51%, 77.40%, 60.11%, 81.17%, 72.07%, 78.95% and 85.42% (all p < 0.0001), respectively, when compared to that of wildtype zebrafish; superoxide dismutase and catalase activities, and glutathione levels in rpgrip1 mutant zebrafish eyes were significantly decreased by 87.21%, 21.55% and 96.51% (all p < 0.0001), respectively. There were marked increases in the production of reactive oxygen species (ROS) and malondialdehyde (MDA) by 2738.73% and 510.69% (all p < 0.0001), respectively, in rpgrip1 mutant zebrafish eyes; expression of pro-inflammatory cytokines IL-1ß, IL-6 and TNF-α was also significantly increased by 150.11%, 267.79% and 190.72% (all p < 0.0001), respectively, in rpgrip1 mutant zebrafish eyes, compared to that of wildtype zebrafish. Treatment with Gyp significantly counteracted these effects. This study indicates that Gyp has a potential role in the treatment of RP.

Iron-Chelating Drugs Enhance Cone Photoreceptor Survival in a Mouse Model of Retinitis Pigmentosa.

Purpose: Retinitis pigmentosa (RP) is a group of hereditary retinal degeneration in which mutations commonly result in the initial phase of rod cell death followed by gradual cone cell death. The mechanisms by which the mutations lead to photoreceptor cell death in RP have not been clearly elucidated. There is currently no effective treatment for RP. The purpose of this work was to explore iron chelation therapy for improving cone survival and function in the rd10 mouse model of RP. Methods: Two iron-chelating drugs, 5-(4-(2-hydroxyethyl) piperazin-1-yl (methyl)-8-hydroxyquinoline (VK28) and its chimeric derivative 5-(N-methyl-N-propargyaminomethyl)-quinoline-8-oldihydrochloride (VAR10303), were injected intraperitoneally to rd10 mice every other day starting from postnatal day 14. We investigate the effects of the two compounds on cone rescue at three time points, using a combination of immunocytochemistry, RT-PCR, Western blot analysis, and a series of visual function tests. Results: VK28 and VAR10303 treatments partially rescued cones, and significantly improved visual function in rd10 mice. Moreover, we showed that the neuroprotective effects of VK28 and VAR10303 were correlated to inhibition of neuroinflammation, oxidative stress, and apoptosis. Furthermore, we demonstrated that downregulation of NF-kB and p53 is likely to be the mechanisms by which proinflammatory mediators and apoptosis are reduced in the rd10 retina, respectively. Conclusions: VK28 and VAR10303 provided partial histologic and functional rescue of cones in RD10 mice. Our study demonstrated that iron chelation therapy might represent an effective therapeutic strategy for RP patients.

Anti-Aging Approach for Ocular Disorders: from Dry Eye to Retinitis Pigmentosa and Myopia.

More than 90% of ocular diseases, such as glaucoma, age-related macular degeneration, and dry eye, are age-related with the incidence increasing with age. Furthermore, although retinitis pigmentosa and myopia may be associated with hereditary factors, they are also considered age-related diseases since they progress with aging. Thus, instead of targeting individual diseases, a new approach aimed at targeting aging itself is being examined. The most established current anti-aging approach is calorie restriction, considered to induce various gene expressions such as anti-oxidative enzymes contributing to life extension. At first, we confirmed that conditions under increased oxidative stresses, including genetically modified animals, such as Sod-1 knockout mice (KO), Mev1 transgenic mice, and Nrf-2 KO mice, and smoking induces a decrease in tear secretion resulting in dry eye. Recently, we found that dietary supplements containing lactoferrin or lactic acid bacteria suppress oxidative stress in the lacrimal glands, these results need to be considered in association with the current advances in the microbiome research. It is now possible to promote the clinical use of those supplements to increase tear secretion. Calorie restriction (CR) activates longevity gene sirtuins. We also have shown that agents activating sirtuins, such as resveratrol or nicotinamide mononucleotide (NMN) have retinal protective effects. Particularly, NMN is promising since we have confirmed its therapeutic effect against retinitis pigmentosa. Ketone bodies are considered another mechanistic target of CR. We developed eye drops containing ketone bodies, and confirmed a therapeutic effect similar to that of CR. Now we are expanding our investigations to include new therapies for dry eye and neuroprotection for the retina and the optic nerve. Other pathways such as endoplasmic reticulum (ER) stress, inhibition of hypoxia-inducible factor (HIF), and inhibition of the insulin-like growth factor (IGF) are also considered to be targets for the anti-aging approach. Taken together, the new strategy "anti-aging" is one approach in dealing with ocular diseases. The anti-aging approach is promising as the next generation of preventive medicine focusing on aging for the current era with increased health care expenditures.

(2R, 3S)-Pinobanksin-3-cinnamate ameliorates photoreceptor degeneration in Pde6rd10 mice.

As an inherited disorder caused by initial death of rod photoreceptors, retinitis pigmentosa is currently untreatable and usually leads to partial or complete blindness. (2R, 3S)-Pinobanksin-3-cinnamate (PC) is a new flavonone isolated from the seed of Alpinia galanga Willd, and has been reported to exert neuroprotective effects by upregulating endogenous antioxidant enzymes. In this study, the anti-oxidative and neuroprotective activity of PC against photoreceptor apoptosis in rd10 mouse model of retinitis pigmentosa was explored. PC showed to produce significant improvement in histology and function in rd10 mice through reducing oxidative stress. For the first time, the protective effects of PC were demonstrated against retina degeneration in rd10 mice and our study provides scientific rationale on using PC as the supplementary treatment to the outer retina diseases, including retinitis pigmentosa, in which oxidative stress is thought to contribute to disease progression.

Safety assessment of docosahexaenoic acid in X-linked retinitis pigmentosa: the 4-year DHAX trial.

PURPOSE: Docosahexaenoic acid (DHA) continues to be evaluated and recommended as treatment and prophylaxis for various diseases. We recently assessed efficacy of high-dose DHA supplementation to slow vision loss in patients with X-linked retinitis pigmentosa (XLRP) in a randomized clinical trial. Because DHA is a highly unsaturated fatty acid, it could serve as a target for free-radical induced oxidation, resulting in increased oxidative stress. Biosafety was monitored during the 4-year trial to determine whether DHA supplementation was associated with identifiable risks. METHODS: Males (n = 78; 7-31 years) meeting entry criteria were enrolled. The modified intent-to-treat cohort (DHA = 33; placebo = 27) adhered to the protocol ≥ 1 year. Participants were randomized to an oral dose of 30 mg/kg/d DHA or placebo plus a daily multivitamin. Comprehensive metabolic analyses were assessed for group differences. Treatment-emergent adverse events including blood chemistry metabolites were recorded. RESULTS: By year 4, supplementation elevated plasma and red blood cell-DHA 4.4- and 3.6-fold, respectively, compared with the placebo group (P < 0.00001). Over the trial duration, no significant differences between DHA and placebo groups were found for vitamin A, vitamin E, platelet aggregation, antioxidant activity, lipoprotein cholesterol, or oxidized LDL levels (all P > 0.14). Adverse events were transient and not considered severe (e.g., gastrointestinal [GI] irritability, blood chemistry alterations). One participant was unable to tolerate persistent GI discomfort. CONCLUSIONS: Long-term, high-dose DHA supplementation to patients with XLRP was associated with limited safety risks in this 4-year trial. Nevertheless, GI symptoms should be monitored in all patients taking high dose DHA especially those with personal or family history of GI disturbances. (ClinicalTrials.gov number, NCT00100230.).

Retinitis pigmentosa mutants provide insight into the role of the N-terminal cap in rhodopsin folding, structure, and function.

Autosomal dominant retinitis pigmentosa (ADRP) mutants (T4K, N15S, T17M, V20G, P23A/H/L, and Q28H) in the N-terminal cap of rhodopsin misfold when expressed in mammalian cells. To gain insight into the causes of misfolding and to define the contributions of specific residues to receptor stability and function, we evaluated the responses of these mutants to 11-cis-retinal pharmacological chaperone rescue or disulfide bond-mediated repair. Pharmacological rescue restored folding in all mutants, but the purified mutant pigments in all cases were thermo-unstable and exhibited abnormal photobleaching, metarhodopsin II decay, and G protein activation. As a complementary approach, we superimposed this panel of ADRP mutants onto a rhodopsin background containing a juxtaposed cysteine pair (N2C/D282C) that forms a disulfide bond. This approach restored folding in T4K, N15S, V20G, P23A, and Q28H but not T17M, P23H, or P23L. ADRP mutant pigments obtained by disulfide bond repair exhibited enhanced stability, and some also displayed markedly improved photobleaching and signal transduction properties. Our major conclusion is that the N-terminal cap stabilizes opsin during biosynthesis and contributes to the dark-state stability of rhodopsin. Comparison of these two restorative approaches revealed that the correct position of the cap relative to the extracellular loops is also required for optimal photochemistry and efficient G protein activation.

NARP mutation and mtDNA depletion trigger mitochondrial biogenesis which can be modulated by selenite supplementation.

The importance of mitochondrial biogenesis in the pathogenesis of mitochondrial diseases has been widely recognised but little is known about it with regard to NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) syndrome. Since such knowledge would contribute to the understanding of the pathogenesis of this disease, we designed a study to provide comprehensive overview of mitochondrial biogenesis in cybrid cells harboring NARP mutation (8993T>G). We also used Rho0 cells with the same nuclear background to show that distinct mtDNA defects lead to distinct cellular responses irrespective of nuclear genome. Mitochondrial biogenesis is regulated by mitochondria-to-nucleus (retrograde) communication which depends on intracellular signaling pathways sensitive to ROS. Since we previously found that selenite lowered ROS in NARP cybrids, we hypothesised that selenite could also modulate mitochondrial biogenesis in these cells. Although the mitochondrial mass was not changed in NARP cybrids, we showed the compensatory upregulation of respiratory chain subunits which prompted us to investigate the transcription factors that regulate their expression such as PGC-1α, NRFs, and TFAM. Selenite supplementation increased the level of NRF1 and nuclear accumulation of NRF2, but we did not detect any major changes in the levels of investigated respiratory chain proteins. These subtle changes in mitochondrial biogenesis in response to selenite treatment support the hypothesis that selenite could be considered as a potential therapeutic agent of NARP syndrome due to its antioxidant properties. Moreover, it could also be tested with regard to other mitochondrial disorders associated with ROS overproduction.

Cut-like homeobox 1 (CUX1) regulates expression of the fat mass and obesity-associated and retinitis pigmentosa GTPase regulator-interacting protein-1-like (RPGRIP1L) genes and coordinates leptin receptor signaling.

The first intron of FTO contains common single nucleotide polymorphisms associated with body weight and adiposity in humans. In an effort to identify the molecular basis for this association, we discovered that FTO and RPGRIP1L (a ciliary gene located in close proximity to the transcriptional start site of FTO) are regulated by isoforms P200 and P110 of the transcription factor, CUX1. This regulation occurs via a single AATAAATA regulatory site (conserved in the mouse) within the FTO intronic region associated with adiposity in humans. Single nucleotide polymorphism rs8050136 (located in this regulatory site) affects binding affinities of P200 and P110. Promoter-probe analysis revealed that binding of P200 to this site represses FTO, whereas binding of P110 increases transcriptional activity from the FTO as well as RPGRIP1L minimal promoters. Reduced expression of Fto or Rpgrip1l affects leptin receptor isoform b trafficking and leptin signaling in N41 mouse hypothalamic or N2a neuroblastoma cells in vitro. Leptin receptor clusters in the vicinity of the cilium of arcuate hypothalamic neurons in C57BL/6J mice treated with leptin, but not in fasted mice, suggesting a potentially important role of the cilium in leptin signaling that is, in part, regulated by FTO and RPGRIP1L. Decreased Fto/Rpgrip1l expression in the arcuate hypothalamus coincides with decreased nuclear enzymatic activity of a protease (cathepsin L) that has been shown to cleave full-length CUX1 (P200) to P110. P200 disrupts (whereas P110 promotes) leptin receptor isoform b clustering in the vicinity of the cilium in vitro. Clustering of the receptor coincides with increased leptin signaling as reflected in protein levels of phosphorylated Stat3 (p-Stat3). Association of the FTO locus with adiposity in humans may reflect functional consequences of A/C alleles at rs8050136. The obesity-risk (A) allele shows reduced affinity for the FTO and RPGRIP1L transcriptional activator P110, leading to the following: 1) decreased FTO and RPGRIP1L mRNA levels; 2) reduced LEPR trafficking to the cilium; and, as a consequence, 3) a diminished cellular response to leptin.

Antioxidant defence systems and generation of reactive oxygen species in osteosarcoma cells with defective mitochondria: effect of selenium.

Mitochondrial diseases originate from mutations in mitochondrial or nuclear genes encoding for mitochondrial proteome. Neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) syndrome is associated with the T8993G transversion in ATP6 gene which results in substitution at the very conservative site in the subunit 6 of mitochondrial ATP synthase. Defects in the mitochondrial respiratory chain and the ATPase are considered to be accompanied by changes in the generation of reactive oxygen species (ROS). This study aimed to elucidate effects of selenium on ROS and antioxidant system of NARP cybrid cells with 98% of T8993G mutation load. We found that selenium decreased ROS generation and increased the level and activity of antioxidant enzymes such as glutathione peroxidase (GPx) and thioredoxin reductase (TrxR). Therefore, we propose selenium to be a promising therapeutic agent not only in the case of NARP syndrome but also other diseases associated with mitochondrial dysfunctions and oxidative stress.

Ganoderma spore lipid inhibits N-methyl-N-nitrosourea-induced retinal photoreceptor apoptosis in vivo.

The purpose of the present study was to investigate the effect of Ganoderma spores lipid (GSL) on Bax, Bcl-xl and Caspase-3 expression in damaged retina and to address the effect of GSL on photoreceptor cell lesions induced by N-methyl-N-nitrosourea (MNU). Thirty 50-day-old female Sprague-Dawley rats were divided randomly into five groups to detect the dose-response effect of GSL by electroretinogram (ERG) analysis. Four groups received different daily GSL doses (0.5, 1, 2 and 4 g/kg, respectively) and one control group received no treatment. Sixty rats were divided randomly into an untreated MNU model control group and the GSL treatment group. Retina tissue samples were obtained sequentially 0 h before and 1, 3, 7 and 10 d after MNU injection. Expressions of Bax, Bcl-xl and Caspase-3 were detected by RT-PCR and immunofluorescence assays, then photoreceptor cell apoptosis was confirmed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling (TUNEL) signals. GSL had a dose-response effect on retina ERG and reversed retinal photoreceptor damage induced by MNU. RT-PCR analysis demonstrated that transcription levels of Bax, Bcl-xl and Caspase-3 in MNU control group and GSL treatment group were all upregulated on 1 d (p < 0.01) and peaked on 3 d (p < 0.01) after MNU injection compared to before MNU injection. GSL treatment significantly decreased mRNA levels of Bax on 1, 3, 7 and 10 d vs. MNU group (all p < 0.01) and mRNA levels of Caspase-3 on 1, 3, 7 d (p < 0.01) and 10 d (p < 0.05) vs. MNU group. Bcl-xl was clearly upregulation on 1, 3, 7 and 10 d vs. MNU group (all p < 0.01). Expression ratios of Bax/Bcl-xl were raised after MNU injection on 1 and 3 d vs. 0 h before MNU (both p < 0.01), peaked on 3 d, then dropped after GSL treatment on 1, 3, 7 and 10 d vs. MNU group (all p < 0.01). Immunofluorescence assays showed GSL decreased Bax and Caspase-3 positive staining levels in retina and increased Bcl-xl level. TUNEL-positive cells were evoked only in the outer nuclear layer and peaked on 3 d in rats receiving MNU (p < 0.01 vs. 0 h before MNU). GSL administration decreased apoptosis levels significantly, and the apoptotic indexes (AIs) of the GSL group were lower than those of MNU group on 1 and 3 d (both p < 0.01). Taken together, these data suggest that GSL may regulate the expressions of Bax, Bcl-xl and Caspases-3, inhibiting MNU-induced rat photoreceptor cell apoptosis and protecting retinal function.

Systemic aminoglycoside treatment in rodent models of retinitis pigmentosa.

We studied the potential of systemically administered aminoglycosides as a therapy for retinal degeneration resulting from premature termination codon (PTC) mutations. Aminoglycosides were systemically delivered to two rodent models of retinal degeneration: a transgenic rat model of dominant disease caused by a PTC in rhodopsin (S334ter); and a mouse model of recessive disease (rd12) caused by a PTC in the retinoid isomerase Rpe65. Initial luciferase reporter assays were undertaken to measure the efficiency of gentamicin-induced read-through in vitro. These experiments indicated that gentamicin treatment induced on average a 5.3% extra read-through of the S334ter PTC in vitro, but did not affect the rd12 PTC. Beginning at postnatal day 5, animals received daily subcutaneous injections of gentamicin or geneticin at a range of doses. The effect of the treatment on retinal degeneration was examined by histopathology and electroretinography (ERG). Systemic treatment with aminoglycoside significantly increased the number of surviving photoreceptors in the S334ter rat model over several weeks of treatment, but was not effective in slowing the retinal degeneration in the rd12 mouse model. Similarly, ERG recordings indicated better preservation of retinal function in the treated S334ter rats, but no difference was observed in the rd12 mice. Daily subcutaneous injection of 12.5mug/g gentamicin was the only regimen that inhibited retinal degeneration without apparent adverse systemic side effects. Reduced effectiveness beyond postnatal day 50 correlated with reduced ocular penetration of drug as seen in gentamicin-Texas red (GTTR) conjugation experiments. We conclude that, in the rat model, an approximately 5% reduction of abnormal truncated protein is sufficient to enhance photoreceptor survival. Such a change in truncated protein is consistent with beneficial effects seen when aminoglycosides has been used in other, non-ocular animal models. In the rd12 mouse, lack of efficacy was seen despite this particular PTC being theoretically more sensitive to aminoglycoside modification. We conclude that aminoglycoside read-through of PTCs in vitro and in vivo cannot be predicted just from genomic context. Because there is considerable genetic heterogeneity amongst retinal degenerations, pharmacologic therapies that are not gene-specific have significant appeal. Our findings suggest that if adverse issues such as systemic toxicity and limited ocular penetration can be overcome, small molecule therapeutics, such as aminoglycosides, which target classes of mutation could hold considerable potential as therapies for retinal disease.

Effects of electroacupuncture on retinal nerve growth factor and brain-derived neurotrophic factor expression in a rat model of retinitis pigmentosa.

The aim of this study was to investigate the effect of electroacupuncture (EA) on the progression of retinal degeneration in rats affected by inherited retinitis pigmentosa (IRP) and to correlate this event with the retinal expression of neurotrophins. Thirty-day-old Royal College of Surgeons (RCS) rats were exposed to 25-min-long daily sessions of low-frequency EA for 11 consecutive days. Control-untreated and EA-treated rats were sacrificed 1 h after the last EA session, and their retina removed for biochemical, molecular, and immunohistochemical analyses. Our data revealed that daily sessions of low-frequency EA for 11 days to RCS rats during a critical developmental stage of retinal cell degeneration cause an increase of retinal nerve growth factor (NGF) and NGF high-affinity receptor (TrkA) expression; and increase of outer nuclear layer (ONL) thickness; and enhanced vascularization. These findings suggest the possible beneficial effects of EA treatment in the development of IRP-like retinal degeneration of RCS rats and that the mechanism through which EA might exerts its action on the regulation of NGF and brain-derived neurotrophic factor (BDNF) and/or their receptors in retinal cells.