In the retina, pH fluctuations may play an important role in adapting retinal responses to different light intensities and are involved in the fine tuning of visual perception. Acidosis occurs in the subretinal space (SRS) under pathological conditions such as age-related macular degeneration (AMD). Although it is well known that many transporters in the retinal pigment epithelium (RPE) cells can maintain pH homeostasis efficiently, other receptors in RPE may also be involved in sensing acidosis, such as acid-sensing ion channels (ASICs). In this study, we investigated whether ASIC1a was expressed in the RPE cells and whether it was involved in the function of these cells. Real-time RT-PCR and Western blotting were used to analyze the ASIC1a expression in ARPE-19 cells during oxidative stress induced by hydrogen peroxide (H(2)O(2)). Furthermore, inhibition or over-expression of ASIC1a in RPE cells was obtained using inhibitors (amiloride and PCTx1) or by the transfection of cDNA encoding hASIC1a. Cell viability was determined by using the MTT assay. The real-time RT-PCR and Western blotting results showed that both the mRNA and protein of ASIC1a were expressed in RPE cells. Inhibition of ASICs by amiloride in normal RPE cells resulted in cell death, indicating that ASICs play an important physiological role in RPE cells. Furthermore, over-expression of ASIC1a in RPE cells prolonged cell survival under oxidative stress induced by H(2)O(2). In conclusion, ASIC1a is functionally expressed in RPE cells and may play an important role in the physiological function of RPE cells by protecting them from oxidative stress.
Acid Sensing Ion Channels ; metabolism ; Cell Line ; Humans ; Ion Channel Gating ; physiology ; Oxidative Stress ; physiology ; Retinal Pigment Epithelium ; cytology ; metabolism

BACKGROUNDAdenosine receptors (ADORs) have been reported to play a role in experimental myopia. This study aimed to determine the distribution of ADORs in human retinal pigment epithelium (RPE) cells cultured in vitro.

METHODSHuman RPE cells (cell line D407) were cultured in vitro. ADOR mRNA in RPE was detected by reverse transcription polymerase chain reaction. ADOR protein expression in RPE was confirmed by Western blotting analysis of cell lysates. Confocal fluorescence microscopy was used to study the subcellular distribution of ADORs.

RESULTSAll four subtypes of ADORs mRNA and protein were expressed in human RPE. This was confirmed by Western blotting analysis. The ADOR subtypes were differently distributed within the cells. ADORA1 was expressed in nucleus, perinucleus and cytoplasm of RPE. ADORA2A was concentrated mainly in one side of the perinucleus and cytoplasm of RPE. ADORA2B was strongly expressed in the nucleus, perinucleus and the cytoplasm, and ADORA3 was expressed weakly in the cytoplasm of RPE.

CONCLUSIONSADORs are expressed in human RPE. The different distribution at the subcellular level suggests different functions of ADOR subtypes.

Blotting, Western ; Cell Line ; Fluorescent Antibody Technique, Indirect ; Humans ; Receptors, Purinergic P1 ; genetics ; metabolism ; Retinal Pigment Epithelium ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

The present study was designed to analyze the metabolites of all-trans-retinal (atRal) and compare the cytotoxicity of atRal versus its derivative all-trans-retinoic acid (atRA) in human retinal pigment epithelial (RPE) cells. We confirmed that atRA was produced in normal pig neural retina and RPE. The amount of all-trans-retinol (atROL) converted from atRal was about 2.7 times that of atRal-derived atRA after incubating RPE cells with 10 μmol/L atRal for 24 h, whereas atRA in medium supernatant is more plentiful (91 vs. 29 pmol/mL), suggesting that atRA conversion facilitates elimination of excess atRal in the retina. Moreover, we found that mRNA expression of retinoic acid-specific hydroxylase CYP26b1 was dose-dependently up-regulated by atRal exposure in RPE cells, indicating that atRA inactivation may be also initiated in atRal-accumulated RPE cells. Our data show that atRA-caused viability inhibition was evidently reduced compared with the equal concentration of its precursor atRal. Excess accumulation of atRal provoked intracellular reactive oxygen species (ROS) overproduction, heme oxygenase-1 (HO-1) expression, and increased cleaved poly(ADP-ribose) polymerase 1 (PARP1) expression in RPE cells. In contrast, comparable dosage of atRA-induced oxidative stress was much weaker, and it could not activate apoptosis in RPE cells. These results suggest that atRA generation is an antidotal metabolism pathway for atRal in the retina. Moreover, we found that in the eyes of ABCA4^-/-RDH8^-/- mice, a mouse model with atRal accumulation in the retina, the atRA content was almost the same as that in the wild type. It is possible that atRal accumulation simultaneously and equally promotes atRA synthesis and clearance in eyes of ABCA4^-/-RDH8^-/- mice, thus inhibiting the further increase of atRA in the retina. Our present study provides further insights into atRal clearance in the retina.
ATP-Binding Cassette Transporters/physiology* ; Alcohol Oxidoreductases/physiology* ; Animals ; Cell Survival/drug effects* ; Cells, Cultured ; Humans ; Inactivation, Metabolic ; Mice ; Retina/metabolism* ; Retinal Pigment Epithelium/metabolism* ; Swine ; Tretinoin/pharmacology*

OBJECTIVETo observe the contribution of Borneolum syntheticum to the intervention effect of Liuwei Dihuang Pill (, LDP) on experimental retinal degeneration, and initially investigate the mechanism of Borneolum syntheticum as meridian-lead-in drug.

METHODSA total of 180 sodium iodateinduced retinital degeneration rats were randomly divided into three groups, including distilled water group, LDP group, and LDP+Borneolum syntheticum (LDP+BS) group. Twenty normal rats were fed regularly without any treatment as normal control. On day 7 and 14 after treatment, histopathological study and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) test were performed to evaluate the retinopathy. Claudin-5 expression at blood-retina barrier (BRB) was detected by Western blot at different time points from 0.5 to 8 h after gavage.

RESULTSOn day 7 and 14 after treatment, the retinal lesion grades were significantly different among the three groups (P<0.05). The grade in the LDP+BS group was significantly less than the LDP and distilled water groups (both P<0.05), no significant difference was observed between the LDP and distilled water groups (P>0.05). The apoptosis rates in the LDP+BS group was significantly less than the distilled water and LDP groups (both P<0.05), while there was no significant difference between LDP and distilled water groups (P>0.05). Expression of claudin-5 in LDP+BS group was significantly less than the other two groups at 0.5, 1 and 2 h after gavage (P<0.05). There was no apparent difference among the three groups at 4 and 8 h after gavage (P>0.05).

CONCLUSIONBorneolum syntheticum could strengthen the effect of LDP on experimental retinal degeneration, indicated that Borneolum syntheticum might play the role of meridian-lead-in drug in the formula. The mechanism may be due to Borneolum syntheticum could promote the physiologically openness of bloodretina barrier through transiently affecting the expression of claudin-5.

Animals ; Apoptosis ; drug effects ; Claudin-5 ; metabolism ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Rats, Sprague-Dawley ; Retinal Degeneration ; chemically induced ; drug therapy ; pathology ; Retinal Pigment Epithelium ; drug effects ; pathology ; Time Factors

The purpose of this study was to investigate the molecular mechanisms whereby hydrogen sulfide (H2S) exerts the promoting effect on vascular endothelial cells migration. We used wound healing assay to study the effect of NaHS (H2S donor) on the migration ability of rhesus retinal pigment epithelial cell line, RF/6A cells, under normoxic conditions. Real-time PCR was used to measure hypoxia-inducible factor 1α (HIF-1α) mRNA level. Western blot was used to measure the expression of HIF-1α protein. The probe 2',7'-dichlorofluorescein diacetate (DCFH-DA) was used to measure intracellular reactive oxygen species (ROS) level. The results showed that NaHS (10-100 μmol/L) could significantly promote RF/6A cells migration under normoxic conditions, and this effect could be inhibited by 50 µmol/L HIF-1 inhibitor, CdCl2. NaHS increased the protein level of HIF-1α in a dose- and time-dependent manner, and up-regulated the mRNA level of HIF-1α quickly and continuously. Moreover, NaHS could significantly decrease ROS levels in RF/6A cells under normoxic conditions. These results suggest HIF-1 may mediate the promoting effect of H2S on vascular endothelial cells migration under normoxic conditions. ROS, as an upstream regulator of HIF-1α, may be involved in the migration-promoting effect of H2S.
Animals ; Cell Line ; Cell Movement ; physiology ; Endothelial Cells ; cytology ; Hydrogen Sulfide ; metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit ; genetics ; metabolism ; Macaca mulatta ; RNA, Messenger ; genetics ; metabolism ; Reactive Oxygen Species ; metabolism ; Retinal Pigment Epithelium ; cytology ; Sulfides ; pharmacology

OBJECTIVE: To investigate the regulation of atropine to the expression and secretion of TGF-beta2 in retinal pigment epithelium (RPE) cells by observing the changes of those under different treatments of atropine and carbachol. METHODS: D407 cells were cultured conventionally and divided into 4 groups as follows: (1) An experimental group (Group A), cells were pretreated with 10(-4)-10(-8) mol/L atropine for 30 min, and then treated with 10(-5) mol/L carbachol; (2) a negative control group (Group B), cells were treated with 10(-4)-10(-8) mol/L atropine; (3) a positive control group (Group C), cells were treated with 10(-5) mol/L carbachol; (4) a blank control group (Group D). The concentration of TGF-beta2 in the supernate, and the level of TGF-beta2 mRNA and protein were measured by ELISA, RT-PCR, and Western blot after the 24-hour treatment. The data were analyzed by analysis of variance. RESULTS: The levels of TGF-beta2 mRNA and protein in the cytoplasm and the concentration of TGF-beta2 in the supernate in the experimental groups were lower than those of the positive control group. Atropine at 10-4 mol/L could completely inhibit the effect of carbachol at 10-5 mol/L. The effect of atropine was concentration-dependent (F=1,056.897,1,320.170, and 475.657; P<0.001). There was no change of TGF-beta2 level in the cytoplasm and supernate with the treatment of atropine alone (P>0.05). CONCLUSION Carbachol can promote the expression and secretion of TGF-beta2 in human RPE cells and atropine could reverse it effectively, suggesting that M receptor may be involved.
Adult ; Atropine ; pharmacology ; Carbachol ; pharmacology ; Cell Line ; Female ; Humans ; Male ; Muscarinic Antagonists ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Retinal Pigment Epithelium ; cytology ; metabolism ; Transforming Growth Factor beta2 ; genetics ; metabolism ; Young Adult

The aim of this study is to prepare hyaluronic acid (HA) modified core-shell liponanoparticles (pHA-LCS-NPs) as gene delivery system and investigate its gene transfection efficiency in human retinal pigment epithelium (ARPE-19) cells in vitro. The pHA-LCS-NPs was prepared by firstly hydrating dry lipid film with CS-NPs suspension to get LCS-NPs, then modifying the lipid bilayer with HA by amidation reaction between HA and dioleoyl phosphatidylethanolamine (DOPE). Its morphology, particle size and zeta potential were investigated. XTT assay was used to evaluate the cell safety of different vectors in vitro. The gene transfection efficiency of pHA-LCS-NPs modified with different contents of HA was investigated in ARPE-19 cells with green fluorescent protein (pEGFP) as the reporter gene. The results showed that the obtained pHA-LCS-NPs exhibited a clear core-shell structure with the average particles size of (214.9 +/- 7.2) nm and zeta potential of (-35 +/- 3.7) mV. The 24 h cumulative release of gene from pHA-LCS-NPs was less than 30%. After 48 h incubation, gene transfection efficiency of pHA-LCS-NPs/pEGFP was 1.81 times and 3.75 times higher than that of CS-NPs/pEGFP and naked pEGFP, respectively. Also no obvious cytotoxicity was observed on pHA-LCS-NPs. It suggested that the pHA-LCS-NPs might be promising non-viral gene delivery systems with high efficiency and low cytotoxicity.
Cell Survival ; Gene Transfer Techniques ; Genes, Reporter ; Genetic Vectors ; Green Fluorescent Proteins ; metabolism ; Humans ; Hyaluronic Acid ; chemistry ; pharmacology ; Lipids ; Nanoparticles ; Particle Size ; Phosphatidylethanolamines ; chemistry ; pharmacology ; Retinal Pigment Epithelium ; drug effects ; Transfection

The role of methyl-CpG binding domain protein 2 (MBD2) in an ApoE-deficient mouse model of age-related macular degeneration (AMD) was investigated. Eight-week-old Mbd2/ApoE double deficient (Mbd2(-/-) ApoE(-/-)) mice (n=12, 24 eyes, experimental group) and MBD2 (wt) ApoE(-/-) mice (n=12, 24 eyes, control group) were fed on Western-type diet for 4 months. The mice were sacrificed, and total serum cholesterol levels were analyzed and Bruch's membrane (BM) of the eyes was removed for ultrastructural observation by transmission electron microscopy. Moreover, intercellular adhesion molecule 1 (ICAM-1) immunoreactivities were evaluated by fluorescence microscopy in sections of the eyes in both groups for further understanding the function mechanism of MBD2. There was no significant difference in the total serum cholesterol levels between control group and experimental group (P>0.05). Transmission electron microscopy revealed that AMD-like lesions, various vacuoles accumulated on BM, notable outer collagenous layer deposits and dilated basal infoldings of retinal pigment epithelium (RPE) were seen in both groups, and the BM in control group was significantly thickened as compared with experimental group (P<0.05). Fluorescence micrographs exhibited the expression of ICAM-1 in choroid was higher in control group than in experimental group. We are led to conclude that MBD2 gene knockout may lead to accumulation of more deposits on the BM and influence the pathogenesis of AMD via triggering endothelial activation and inflammatory response in choroid, improving microcirculation, and reducing lipid deposition so as to inhibit the development of AMD-like lesions. Our study helps to provide a new therapeutic approach for the clinical treatment of AMD.
Animals ; Apolipoproteins E ; genetics ; metabolism ; Bruch Membrane ; metabolism ; ultrastructure ; Cholesterol ; blood ; Choroid ; metabolism ; ultrastructure ; DNA-Binding Proteins ; genetics ; metabolism ; Intercellular Adhesion Molecule-1 ; metabolism ; Macular Degeneration ; blood ; genetics ; metabolism ; Male ; Mice ; Mice, Knockout ; Microscopy, Electron, Transmission ; Microscopy, Fluorescence ; Retinal Pigment Epithelium ; metabolism ; ultrastructure

The generation of functional retinal pigment epithelium (RPE) is of great therapeutic interest to the field of regenerative medicine and may provide possible cures for retinal degenerative diseases, including age-related macular degeneration (AMD). Although RPE cells can be produced from either embryonic stem cells or induced pluripotent stem cells, direct cell reprogramming driven by lineage-determining transcription factors provides an immediate route to their generation. By monitoring a human RPE specific Best1::GFP reporter, we report the conversion of human fibroblasts into RPE lineage using defined sets of transcription factors. We found that Best1::GFP positive cells formed colonies and exhibited morphological and molecular features of early stage RPE cells. Moreover, they were able to obtain pigmentation upon activation of Retinoic acid (RA) and Sonic Hedgehog (SHH) signaling pathways. Our study not only established an ideal platform to investigate the transcriptional network regulating the RPE cell fate determination, but also provided an alternative strategy to generate functional RPE cells that complement the use of pluripotent stem cells for disease modeling, drug screening, and cell therapy of retinal degeneration.
Animals ; Bestrophins ; Cell Differentiation ; Cell Line ; Cell Lineage ; Chloride Channels ; genetics ; metabolism ; Embryonic Stem Cells ; cytology ; metabolism ; Eye Proteins ; genetics ; metabolism ; Fibroblasts ; cytology ; metabolism ; Genes, Reporter ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Mice ; Pigmentation ; Retinal Pigment Epithelium ; cytology ; metabolism ; Transcription Factors ; metabolism

The purpose of this study was to investigate the protective effect of puerarin on retina pigment epithelial (RPE) cells of diabetic rats against apoptosis. One hundred and eight Sprague-Dawley (SD) rats were randomly divided into 3 groups: control group, streptozotocin (STZ) group and puerarin group. STZ and puerarin groups received 3 d of STZ injection (45 mg/kg per day, i.p.). Additionally, puerarin groups were treated with puerarin (140 mg/kg, i.p.) from the 4th day to the end of experiment. The rats from different groups were sacrificed on 20, 40 and 60 d after STZ injection for harvesting RPE cells. Western blot analysis, DNA laddering, RT-PCR and immunohistochemistry were used for determining the expression of nitrotyrosine (NT, the foot print of peroxynitrite), cell apoptosis, iNOS mRNA and Fas/Fas ligand (FasL) signal transduction in RPE cells, respectively. The results showed that control group maintained low apoptosis level and little NT, iNOS mRNA, Fas/FasL protein expressions, as well as normal blood glucose and body weight during 60 d of the experiment. Compared with control group, STZ group showed obvious apoptosis and higher NT, iNOS mRNA, Fas/FasL protein expressions from 20 d after STZ injection. Puerarin relieved apoptosis of RPE cells and decreased NT, iNOS mRNA, Fas/FasL protein expressions in puerarin group 20 or 40 d after STZ injection, compared with STZ group. These results suggest puerarin can decrease RPE cells apoptosis in diabetic rats by reducing peroxynitrite level and iNOS expression, thus being a potential therapeutic agent in controlling of diabetic retinopathy.
Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Diabetic Retinopathy ; prevention & control ; Fas Ligand Protein ; metabolism ; Isoflavones ; pharmacology ; Male ; Nitric Oxide Synthase Type II ; genetics ; metabolism ; Peroxynitrous Acid ; metabolism ; Protective Agents ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Retinal Pigment Epithelium ; pathology ; fas Receptor ; metabolism