Targeting of integrin beta1 and kinesin 2alpha by microRNA 183.

MicroRNA 183 (miR-183) has been reported to inhibit tumor invasiveness and is believed to be involved in the development and function of ciliated neurosensory organs. We have recently found that expression of miR-183 increased after the induction of cellular senescence by exposure to H(2)O(2). To gain insight into the biological roles of miR-183 we investigated two potential novel targets: integrin beta1 (ITGB1) and kinesin 2alpha (KIF2A). miR-183 significantly decreased the expression of ITGB1 and KIF2A measured by Western blot. Targeting of the 3'-untranslated region (3'-UTR) of ITGB1 and KIF2A by miR-183 was confirmed by luciferase assay. Transfection with miR-183 led to a significant decrease in cell invasion and migration capacities of HeLa cells that could be rescued by expression of ITGB1 lacking the 3'-UTR. Although miR-183 had no effects on cell adhesion in HeLa cells, it significantly decreased adhesion to laminin, gelatin, and collagen type I in normal human diploid fibroblasts and human trabecular meshwork cells. These effects were also rescued by expression of ITGB1 lacking the 3'-UTR. Targeting of KIF2A by miR-183 resulted in some increase in the formation of cells with monopolar spindles in HeLa cells but not in human diploid fibroblast or human trabecular meshwork cells. The regulation of ITGB1 expression by miR-183 provides a new mechanism for the anti-metastatic role of miR-183 and suggests that this miRNA could influence the development and function in neurosensory organs, and contribute to functional alterations associated with cellular senescence in human diploid fibroblasts and human trabecular meshwork cells.

MicroRNA-24 regulates the processing of latent TGFß1 during cyclic mechanical stress in human trabecular meshwork cells through direct targeting of FURIN.

Cyclic mechanical stress (CMS) leads to alterations of cellular functions in the trabecular meshwork (TM), including the up-regulation of transforming growth factor beta 1 (TGFß1), that can potentially contribute to the pathogenesis of glaucoma. Although microRNAs (miRNAs) are known to play important roles in many biological functions, little is known about their potential involvement in the cellular responses elicited by mechanical stress. Here we analyzed changes in miRNA expression induced by CMS, and examined the possible role of miR-24 in the response of human TM cells to CMS. CMS induced the expression of miR-24 that led to the down regulation of the subtilisin-like proprotein convertase FURIN, which is known to play a major role in the processing of TGFß1. FURIN was confirmed as a novel target of miR-24 by 3' UTR luciferase assay and western blot. Overexpression of miR-24 resulted in a significant decrease in activated TGFß1. This effect was mimicked by down regulation of FURIN by siRNA. Conversely, inhibition of miR-24 expression with a specific antagomir led to a small but significant increase in TGFß1. Furthermore, the increase in active TGFß1 induced by CMS in HTM cells was prevented by miR-24. Altogether, our results suggest that miRNAs might contribute to the regulation of responses to CMS in TM cells. Specifically, miR-24 might play an important role in modulating the induction of TGFß1 mediated by CMS through direct targeting of FURIN.

Long-Term Decrease of Intraocular Pressure in Rats by Viral Delivery of miR-146a.

Purpose: To evaluate the effects of miR-146a in trabecular meshwork (TM) cells and on intraocular pressure (IOP) in vivo via viral delivery of miR-146a to the anterior chamber of rat eyes. Methods: Human TM cells were transfected with miR-146 mimic or inhibitor. Some cells from each group were then subjected to cyclic mechanical stress (CMS). Other cells from each group had no force applied. Gene expression was then analyzed by quantitative polymerase chain reaction (qPCR). Replication-deficient adenovirus and lentivirus expressing miR-146a were inoculated into the anterior segment of Brown Norway rat eyes. IOP was monitored by rebound tonometry, visual acuity was evaluated by optokinetic tracking (OKT), and inflammation markers in the anterior segment were examined by slit-lamp, qPCR, and semi-thin sections. Results: miR-146 affected the expression of genes potentially involved in outflow homeostasis at basal levels and under CMS. Both lentiviral and adenoviral vectors expressing miR-146a resulted in sustained decreases in IOP ranging from 2.6 to 4.4 mmHg. Long term follow-up of rats injected with lentiviral vectors showed a sustained effect on IOP of 4.4 ± 2.9 mmHg that lasted until rats were sacrificed more than 8 months later. Eyes showed no signs of inflammation, loss of visual acuity, or other visible abnormalities. Conclusions: Intracameral delivery of miR-146a can provide a long-term decrease of IOP in rats without signs of inflammation or other visible adverse effects. Transitional Relevance: The IOP-lowering effects of miR-146 observed in rats provides a necessary step toward the development of an effective gene therapy for glaucoma in humans.

Assessment of Visual and Retinal Function Following In Vivo Genipin-Induced Scleral Crosslinking.

Purpose: Genipin has been proposed as a possible neuroprotective therapy in myopia and glaucoma. Here, we aim to determine the effects of prolonged genipin-induced scleral stiffening on visual function. Methods: Eyes from Brown Norway rats were treated in vivo with either a single 15 mM genipin retrobulbar injection or sham retrobulbar injection and were compared to naïve eyes. Intraocular pressure, optomotor response, and electroretinograms were repeatedly measured over 4 weeks following retrobulbar injections to determine visual and retinal function. At 4 weeks, we quantified retinal ganglion cell axon counts. Finally, molecular changes in gene and protein expression were analyzed via real-time polymerase chain reaction (RT-PCR) and proteomics. Results: Retrobulbar injection of genipin did not affect intraocular pressure (IOP) or retinal function, nor have a sustained impact on visual function. Although genipin-treated eyes had a small decrease in retinal ganglion cell axon counts compared to contralateral sham-treated eyes (-8,558 ± 18,646; mean ± SD), this was not statistically significant (P = 0.206, n = 9). Last, we did not observe any changes in gene or protein expression due to genipin treatment. Conclusions: Posterior scleral stiffening with a single retrobulbar injection of 15 mM genipin causes no sustained deficits in visual or retinal function or at the molecular level in the retina and sclera. Retinal ganglion cell axon morphology appeared normal. Translational Significance: These results support future in vivo studies to determine the efficacy of genipin-induced posterior scleral stiffening to help treat ocular diseases, like myopia and glaucoma.

Role of miR-29b on the regulation of the extracellular matrix in human trabecular meshwork cells under chronic oxidative stress.

PURPOSE: To investigate the role of miR-29b on the changes in expression of genes involved in the synthesis and deposition of extracellular matrix (ECM) induced by chronic oxidative stress in human trabecular meshwork cells (HTM). METHODS: Changes in gene expression induced by miR-29b in HTM cells were evaluated by gene array analysis using Affymetrix U133A2 arrays and confirmed by quantitative-PCR. Pathway analysis was conducted using Metacore. Targeting of miR-29b to the 3'-untranslated region of three novel putative targets was evaluated using the Psicheck luciferase system. Chronic oxidative stress was induced by incubation at 40% oxygen for 4-5 days, using cultures incubated at 5% oxygen as controls. Changes in expression in microRNA or gene expression were analyzed by Q-PCR. Cell viability was measured by lactate dehydrogenase release. RESULTS: Transfection of HTM cells with miR-29b mimic resulted in downregulation of multiple ECM components, including collagens (COL1A1, COL1A2, COL4A1, COL5A1, COL5A2, COL3A1) LAMC1, and FBN as well as several genes involved in ECM deposition and remodeling, such as SPARC/osteonectin. Three additional genes, BMP1, ADAM12, and NKIRAS2, were identified as direct targets of miR-29b. Chronic oxidative stress induced a significant downregulation of miR-29b in two HTM cell lines that was associated with increased expression of several ECM genes known to be regulated by miR-29b. The increase in expression of these genes was inhibited by transfection with miR-29b mimic. MiR-29b increased cell viability under both chronic oxidative stress and physiologic oxygen concentrations. CONCLUSIONS: MiR-29b negatively regulates the expression of multiple genes involved in the synthesis and deposition of ECM in trabecular meshwork (TM) cells. Downregulation of miR-29b might contribute to increased expression of several ECM genes under chronic oxidative stress conditions. The balance between the activation of ECM production induced by oxidative stress and the protective effects of miR-29b could be a relevant factor in understanding how oxidative damage may lead to increased deposition of ECM in the TM and contribute to the elevation of intra-ocular pressure in glaucoma.

Cross-talk between TGF-beta1 and IL-6 in human trabecular meshwork cells.

PURPOSE: To investigate the relationship between transforming growth factor beta-1 (TGF-beta1) and interleukin-6 (IL-6) in human trabecular meshwork (HTM) cells as well as to identify the signaling pathway/s involved in the increased IL-6 expression that occurs in response to mechanical stress and TGF-beta1. METHODS: All experiments were performed in confluent monolayers of HTM cells at passage 3. Secreted IL-6 was quantified by ELISA. Levels of IL-6 mRNA were evaluated by polymerase chain reaction (PCR) analysis. Activation of the IL-6 and TGF-beta1 promoters was monitored by measuring secreted alkaline phosphatase protein (SEAP) released into the culture medium by HTM cells infected with an adenovirus expressing the SEAP reporter gene that was controlled by either the IL-6 promoter (AdIL6-SEAP) or the TGF-beta1 promoter (AdTGFbeta1-SEAP). Cyclic mechanical stress (5% elongation, one cycle per second) was applied using the Flexcell System. Reagents used in this study included human TGF-beta1, human IL-6, and the inhibitors for the p38 mitogen-activated protein kinase (MAPK; SB202190), c-jun NH2-terminal kinase (JNK; SP600125), extracellular-regulating kinase (ERK; PD98059), and TGF type I activin receptor (SB431542). RESULTS: Incubation of HTM cells with TGF-beta1 (5 ng/ml) resulted in a significant increase in the protein and mRNA levels of IL-6, which was significantly diminished in the presence of the inhibitors for p38 MAPK or JNK. No transcriptional activation of the exogenous IL-6 promoter was observed following TGF-beta1 treatment. In addition, the presence of inhibitors for the p38 MAPK, ERK, and TGF-beta1 pathways significantly decreased the increased expression of IL-6 by cyclic mechanical stress. Furthermore, exposure of HTM cells to IL-6 (100 ng/ml) demonstrated the transcriptional activation of TGF-beta1 promoter, which was severely impaired by blocking the p38 MAPK pathway. CONCLUSIONS: Our results indicate that TGF-beta1 participates in the regulation of basal expression and the stretch-induced expression of IL-6 and suggest the possible existence in cultured HTM cells of an autocrine loop between IL-6 and TGF-beta1. We also found that p38 MAPK might play a contributing role in the maintenance of such a loop.

Alterations in gene expression induced by cyclic mechanical stress in trabecular meshwork cells.

PURPOSE: To investigate the changes in gene expression induced by cyclic mechanical stress (CMS) in trabecular meshwork (TM) cells. METHODS: Human TM cultures from three donors were plated on type I collagen-coated flexible silicone bottom plates and subjected to 15% stretching, one cycle per second for 6 h. Non-stressed parallel control cultures were incubated under the same conditions in the absence of CMS. Total RNA from each culture was amplified (1 round of amplification) and hybridized to Operon Human Oligo Arrays version 3.0 (35 K probes). Differences in gene expression induced by CMS were analyzed using Genespring 7.2. quantitative polymerase chain reaction (Q-PCR) was used to confirm changes in the expressions of 12 selected genes. The effects of chemical inhibitors for p38, ERK (extracellular signal-regulated kinase), JNK (Jun N-terminal kinase), PKA (protein kinase A), PI3K (phosphoinositide 3-kinase), and P2 (purinergic 2) receptors on the induction of MMP3 (matrix metalloproteinase 3), HSP70 (heat shock protein 70), ECSM1 (endothelial cell specific molecule 1), BMP2 (bone morphogenetic protein 2), VEGFC (vascular endothelial growth factor C), and IL-8 (interleukin 8) were evaluated in porcine TM cells subjected to the same regime of CMS as that used in human cells. RESULTS: CMS induced extensive gene expression changes (664 genes, p < or = 0.05) twofold or higher in cultured TM cells. Many of these changes were related to extracellular matrix (ECM) synthesis and remodeling including the upregulation of two metalloproteinases (MMP3 and MMP10). Cytoskeleton and cell adhesion genes were also affected by CMS as well as genes known to be involved in cellular protection against stress including several members of the HSP70 family. Inhibition of PI3K/AKT and P2 receptors pathways significantly reduced the induction of MMP3 and IL-8 whereas the inhibition of the PKA/cAMP pathway decreased ECSM1 and BMP2. CONCLUSIONS: CMS activated many genes that could influence the aqueous humor outflow facility, specifically genes involved in ECM synthesis and remodeling (e.g. MMPs), cytoskeletal organization, and cell adhesion. Induction of MMP3 has the potential to increase the aqueous humor outflow facility and could be part of a homeostatic mechanism involved in the maintenance of normal intraocular pressure (IOP) levels. Other observed changes are more likely to be related to general cellular responses to stress (e.g., HSP70, ECSM1, and BMP2). Although these latter changes may initially help to repair mechanical damage, some of them such as the induction of BMP2 could eventually increase tissue rigidity and compromise the ability of the TM to maintain normal levels of outflow resistance.

Cytoprotective effects of proteasome beta5 subunit overexpression in lens epithelial cells.

PURPOSE: To determine whether the overexpression of the proteasome catalytic beta5 subunit (PSMB5) can induce the expression of the catalytic subunits beta1 and beta2, enhance proteasome activity, and exert a cytoprotective effect in lens epithelial cells. METHODS: Cells from the human lens epithelial cell line SRA01/04 (LECs) were stably transfected either with a plasmid expressing the proteasome catalytic subunit beta5 or with an empty plasmid. beta-5-expressing LECs and controls were analyzed for the expression of beta1, beta2, beta5, and alpha6 proteasome subunits; chymotrypsin-like (CT-L) and peptidylglutamyl-peptide hydrolase (PGPH) catalytic activities; as well as for the accumulation of carbonylated proteins, rates of cell viability, and apoptosis after oxidative stress. RESULTS: Stable expression of the beta5 proteasome subunit resulted in increased expression of the catalytic subunits beta1 and beta2, increased CT-L and PGPH proteasome activities, and increased resistance to accumulation of carbonylated proteins and cell death after oxidative stress. CONCLUSIONS: The proteasome activity can be genetically "upregulated" in lens cells by overexpression of the beta5 catalytic subunit. The resulting increase in proteasome activity leads to a decrease in the accumulation of oxidized proteins and enhanced cell survival following oxidative stress.

Effect of cellular senescence on the P2Y-receptor mediated calcium response in trabecular meshwork cells.

PURPOSE: The objectives of this study were to evaluate the potential release of ATP that is mediated by mechanical stress on trabecular meshwork (TM) cells, to identify the specific P2Y receptors mediating the ATP response, and to determine whether cellular senescence might interfere with the P2Y receptor-mediated calcium response, thus contributing to the loss of physiologic TM function in aging and primary open angle glaucoma (POAG). METHODS: Experiments were conducted using primary cultures of porcine TM cells. Cyclic mechanical stretch (10% stretching/second) was generated using the Flexcell system. ATP release and ectoATPase activity induced by mechanical stress were measured using a luciferin/luciferase assay. Replicative senescence was induced by passing the cells 18 times at a 1:2 split ratio and confirmed by the presence of senescence-associated beta-galactosidase (sa-beta-gal) and autofluorescence. For calcium imaging, cells were plated on gelatin-coated coverslips, bathed in calcium Ringer's solution, and loaded with fluo-4 (5 microM) for 1 h. Agonists of P2Y1 (ADP) and P2Y2/P2Y4 (ATP, UTP) receptors at 10 microM or 100 microM concentrations were added to the bathing medium. Relative changes in cytosolic calcium concentration as a function of time were measured by fluorescent microscopy and reported as peak amplitudes of fluo-4 fluorescence normalized to baseline values (deltaF/Fo). RESULTS: Mechanical stress induced an increase in ATP release from TM cells (258%+/-23% at 15 min, 188%+/-11% at 30 min, and 900%+/-203% at 1 h; p<0.017, n=4) as well as an increase in ectoATPase activity present in the extracellular media during the first 15 min of stress (57%+/-15%, p=0.011, n=4). The P2Y receptor agonists listed above induced a concentration-dependent rise in intracellular calcium in the TM cells. The peak amplitude, deltaF/Fo, was 1.07+/-0.12 (n=3) for 10 microM ADP, 2.59+/-0.33 (n=6) for 100 microM ADP, 1.21+/-0.64 (n=12) for 10 microM UTP, 3.22+/-2.0 (n=12) for 100 microM UTP, 0.88+/-0.40 (n=9) for 10 microM ATP, and 1.37+/-0.61 (n=25) for 100 microM ATP. Cells at passage 18 showed significantly lower levels of intracellular calcium induced by ATP (36%), UTP (34%), and ADP (52%) compared to cells at passage 2, independent from any changes in P2Y receptor changes in expression. CONCLUSIONS: The ability to release ATP in response to mechanical stress and the presence of functional P2Y receptors in TM cells suggest a novel mechanism by which TM cells could sense and respond to changes in intraocular pressure (IOP). In addition, the decrease in P2Y receptor-mediated calcium responses observed in senescent TM cells suggests that the disregulation of calcium homeostasis in senescence may contribute to the alterations of the TM in aging and POAG.

Sustained stress response after oxidative stress in trabecular meshwork cells.

PURPOSE: To investigate the mechanisms by which chronic oxidative stress may lead to a sustained stress response similar to that previously observed in the trabecular meshwork (TM) of glaucoma donors. METHODS: Porcine TM cells were treated with 200 microM H2O2 twice a day for four days and were allowed to recover for three additional days. After the treatment, TM cells were analyzed for generation of intracellular reactive oxygen species (iROS), mitochondrial potential, activation of NF-kappaB, and the expression of inflammatory markers IL-1alpha, IL-6, IL-8, and ELAM-1. Potential sources of iROS were evaluated using inhibitors for nitric oxide, nitric oxide synthetase, cyclooxygenase, xanthine oxidase, NADPH oxidase, mitochondrial ROS, and PKC. The role of NF-kappaB activation in the induction of inflammatory markers was evaluated using the inhibitors Lactacystin and BAY11-7082. RESULTS: Chronic oxidative stress simulated by H2O2 exposure of porcine TM cells resulted in the sustained production of iROS by the mitochondria. Inhibition of mitochondrial iROS had a significant inhibitory effect on the activation of NF-kappaB and the induction of IL-1alpha, IL-6, IL-8, and ELAM-1 triggered by chronic oxidative stress. Inhibition of NF-kappaB partially prevented the induction of IL-1alpha, IL-8, and ELAM-1, but not IL-6. CONCLUSIONS: Chronic oxidative stress in TM cells induced iROS production in mitochondria. This increase in iROS may contribute to the pathogenesis of the TM in glaucoma by inducing the expression of inflammatory mediators previously observed in glaucoma donors as well as the levels of oxidative damage in the tissue.

Regulation of intraocular pressure by microRNA cluster miR-143/145.

Glaucoma is a major cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP), which causes optic nerve damage and retinal ganglion cell death, is the primary risk factor for blindness in glaucoma patients. IOP is controlled by the balance between aqueous humor secretion from the ciliary body (CB) and its drainage through the trabecular meshwork (TM). How microRNAs (miRs) regulate IOP and glaucoma in vivo is largely unknown. Here we show that miR-143 and miR-145 expression is enriched in the smooth muscle and trabecular meshwork in the eye. Targeted deletion of miR-143/145 in mice results in significantly reduced IOP, consistent with an ~2-fold increase in outflow facilities. However, aqueous humor production in the same mice appears to be normal based on a microbeads-induced glaucoma model. Mechanistically, we found that miR-143/145 regulates actin dynamics and the contractility of TM cells, consistent with its regulation of actin-related protein complex (ARPC) subunit 2, 3, and 5, as well as myosin light chain kinase (MLCK) in these cells. Our data establish miR-143/145 as important regulators of IOP, which may have important therapeutic implications in glaucoma.

Genome-wide expression profile of human trabecular meshwork cultured cells, nonglaucomatous and primary open angle glaucoma tissue.

PURPOSE: To contrast genome-wide gene expression profiles of cultured human trabecular meshwork (HTM) cells to that of control and primary open angle glaucoma (POAG) HTM tissues. METHODS: Cultured HTM cells, HTM tissue dissected from control donors, and HTM tissue from POAG donors receiving medication for glaucoma were fixed in RNA latertrade mark. Total RNA extracted from these samples was linearly amplified with the Ovation Biotin RNA Amplification and Labeling System and individually hybridized to Affymetrix Human Genome U133 Plus 2.0 high density microarrays. Data analysis was performed using GeneSpring Software 7.0. Selected genes showing significant differential expression were validated by quantitative real-time PCR in nonamplified RNA. RESULTS: Cultured HTM cells retained the expression of some genes characteristic of HTM tissue, including chitinase 3-like 1 and matrix Gla protein, but demonstrated downregulation of physiologically important genes such as myocilin. POAG HTM tissue showed relatively small changes compared to that of control donors. These changes included the statistically significant upregulation of several genes associated with inflammation and acute-phase response, including selectin-E (ELAM-I), as well as the downregulation of the antioxidants paraoxonase 3 and ceruloplasmin. CONCLUSIONS: Downregulation in cultured HTM cells of genes potentially relevant for outflow pathway function highlights the importance of developing new conditions for the culture of TM cells capable of preserving the characteristics of TM cells in vivo. Comparative analysis between control and POAG tissues suggests that the upregulation of inflammation-associated genes might be involved in the progression of glaucoma.

Juvenile bilateral lens dislocation and glaucoma associated with a novel mutation in the fibrillin 1 gene.

PURPOSE: To describe the clinical, ocular, and genetic findings in multiple members of a family with early-onset and bilateral lens dislocation, clinical corneal guttae, and glaucoma. METHODS: All family members underwent complete physical and ophthalmic examinations. After informed consent was given, DNA was obtained from eleven family members, eight of whom were affected. Three polymorphic markers near the fibrillin 1 (FBN1) locus were genotyped and the results analyzed using the VITESSE program. Amplification of the 65 exons and flanking intronic sequences of FBN1 was performed using polymerase chain reaction (PCR), followed by conformation sensitive gel electrophoresis (CSGE). Then, all fragments with mobility variations were sequenced. RESULTS: Pedigree analysis revealed a three generation family with eight of eleven individuals affected by early onset lens dislocation, high myopia, typical facies, frontal bossing, flexion contractures, proximal interphalangeal (PIP) joint thickening, clinical corneal guttae, and glaucoma. Genetic linkage analysis using polymorphic markers near FBN1 demonstrated an LOD score of 1.78 (maximum possible LOD score 1.78). Conformation sequence gel electrophoresis analysis suggested a sequence variation in exon 3. Sequencing revealed a C965G substitution, resulting in an S322C coding change. This sequence variant segregated with affection status and was not identified in 154 control chromosomes. CONCLUSIONS: This syndrome is consistent with a novel mutation in the FBN1 gene. FBN1 mutations have been previously described as causative for Marfan syndrome. The early-onset of complete lens dislocation, progressive corneal guttae, and glaucoma is unusual for Marfan syndrome. This study expands the Marfan phenotype and demonstrates a possible link between guttae, glaucoma, and fibrillin 1 disorders.

miR-183 Inhibits UV-Induced DNA Damage Repair in Human Trabecular Meshwork Cells by Targeting of KIAA0101.

PURPOSE: The purpose of this study was to investigate the mechanisms by which miR-183 may contribute to the phenotypic alterations associated with stress-induced senescence of human trabecular meshwork (HTM) cells. METHODS: Changes in gene expression induced by miR-183 in HTM cells were evaluated by gene array analysis, confirmed by quantitative-PCR (Q-PCR), and analyzed by MetaCore pathway analysis. Effects of miR-183 on cell proliferation were assessed by incorporation of bromodeoxyuridine incorporation, and DNA damage by CometAssay after ultraviolet (UV) irradiation in primary HTM cells, and confirmed in human diploid fibroblasts (HDF) and HeLa cells. A plasmid expressing KIAA0101 without its 3'-untranslated region (3'-UTR) was cotransfected with miR-183 to evaluate the role of KIAA0101 on the effects induced by miR-183. RESULTS: miR-183 affected the expression of multiple genes involved in cell cycle regulation and DNA damage response in HTM cells. Forced expression of miR-183 in HTM and HDF resulted in a significant decrease in proliferation in primary HTM and HDF cells but not in HeLa cells. In all cell types tested, overexpression of miR-183 resulted in increased DNA damage under UV irradiation. Expression of KIAA0101 lacking the 3'-UTR region partially prevented the effects of miR-183 on cell proliferation and completely reversed the effects on UV-induced DNA damage. CONCLUSIONS: Our results suggest that the observed up-regulation of miR-183 after stress-induced senescence in HTM cells may contribute to reinforce cellular senescence by inhibiting cell cycle progression through multiple gene targets and limiting the DNA repair mechanisms through inhibition of KIAA0101.

Cellular senescence in the glaucomatous outflow pathway.

The mechanisms responsible for the progressive malfunction of the trabecular meshwork (TM)-Schlemm's canal (SC) conventional outflow pathway tissue in primary open angle glaucoma (POAG) are still not fully understood. To determine whether POAG is characterized by an accumulation of senescent cells, similar to what has been described in other diseases, we have compared the levels of the senescence marker senescence-associated-beta-galactosidase (SA-beta-gal) in the outflow pathway cells of POAG and age-matched control donors. POAG donors demonstrated a statistically significant fourfold increase in the percentage of SA-beta-gal positive cells. These results suggest a potential role for cellular senescence in the pathophysiology of the outflow pathway.

Lentiviral mediated gene delivery to the anterior chamber of rodent eyes.

PURPOSE: To study the in vivo efficiency of lentiviral vectors in delivering genes to the trabecular meshwork (TM) of rodent eyes. METHODS: Lentiviral vectors were constructed using the elongation factor 1 alpha (EF-1alpha) promoter driving expression of the green fluorescent protein (GFP) gene. The viral construct was injected intracamerally through the peripheral cornea into the anterior chamber of live rodent eyes. Several variables were evaluated to determine the optimal conditions for TM cell transduction. These parameters included viral concentration, injection volume, needle rotation, and the modulation of anterior chamber current convections. Changes in intraocular pressures (IOPs) were monitored using a Tonopen XL. Signs of inflammation and corneal neovascularization were evaluated by slit lamp observation. Three weeks after injection, the eyes were enucleated and analyzed for GFP expression and distribution. RESULTS: A single intracameral viral dose between 10(7) and 10(8) pfu produced a high and evenly distributed expression of GFP in the TM and corneal endothelial cells. The cornea remained clear and no signs of inflammation were present during the course of the experiment. Moreover, no significant changes in IOPs were observed. CONCLUSIONS: A high transduction efficiency of TM and corneal endothelial cells can be effectively obtained after a single dose of recombinant lentivirus. The EF-1alpha promoter induces high expression of the reporter gene and is a reliable alternative to the CMV promoter when stable, long term expression is desired.

Characterization of four Toll related genes during development and immune responses in Anopheles gambiae.

Toll-like receptors (TLRs) are a group of evolutionary conserved proteins with diverse biological functions. In Drosophila melanogaster, Toll protein plays an important role in pattern formation in embryogenesis and in antimicrobial immunity in larvae and adults. In insects, Toll and two other related proteins, Tehao and 18-wheeler have been shown to participate in the activation of the innate immune responses to fungal and bacterial pathogens. In this paper we report the cloning and characterization of four TLR gene from malaria vector mosquito Anopheles gambiae, AgToll, AgToll6, AgTrex, and AgToll9, orthologues of DmToll, DmToll6, DmTollo (Toll8) and DmToll9 (CG5528) in Drosophila melanogaster. The expression profiles of these genes during development, in different adult tissues and after immune challenge were examined. As expected for the orthologue of Drosophila Toll, AgToll was found to be expressed highly in the ovary and may play a role in pattern formation during embryogenesis. AgToll9, surprisingly, was found to be highly expressed in the adult gut. The potential roles of these genes in development and immunity were discussed.

Quantitative trait loci in Anopheles gambiae controlling the encapsulation response against Plasmodium cynomolgi Ceylon.

BACKGROUND: Anopheles gambiae females are the world's most successful vectors of human malaria. However, a fraction of these mosquitoes is refractory to Plasmodium development. L3-5, a laboratory selected refractory strain, encapsulates transforming ookinetes/early oocysts of a wide variety of Plasmodium species. Previous studies on these mosquitoes showed that one major (Pen1) and two minor (Pen2, Pen3) autosomal dominant quantitative trait loci (QTLs) control the melanotic encapsulation response against P. cynomolgi B, a simian malaria originating in Malaysia. RESULTS: We have investigated the response of L3-5 to infection with P. cynomolgi Ceylon, a different but related parasite species, in crosses with the susceptible strain 4Arr. Refractoriness to this parasite is incompletely recessive. Infection and genotyping of F2 intercross females at genome-spanning microsatellite loci revealed that 3 autosomal QTLs control encapsulation of this species. Two loci map to the regions containing Pen2 and Pen3. The novel QTL maps to chromosome 3R, probably to polytene division 32 or 33. Thus the relative contribution of any QTL to oocyst encapsulation varies with the species of parasite. Further, different QTLs were most readily identified in different F2 families. This, like the F1 data, suggests that L3-5 is not genetically homogeneous and that somewhat different pathways may be used to achieve an encapsulation response. CONCLUSION: We have shown here that different QTLs are involved in responses against different Plasmodium parasites.

Role of microRNAs in the trabecular meshwork.

MicroRNAs (miRNAs) are now recognized as important post-transcriptional regulators of gene expression. MiRNAs are known to modulate cellular functions relevant to the normal and pathological physiology of the trabecular meshwork (TM) such as cell contraction and extracellular matrix turnover. There is also increasing evidence supporting the role of miRNAs in the pathogenesis of multiple diseases, and their potential value as both biomarkers of disease and therapeutic targets. However, compared with other tissues, our current knowledge regarding the roles played by miRNAs in the TM is still very limited. Here, we review the information currently available about miRNAs in the TM and discuss the main challenges and opportunities to incorporate the rapid progress in miRNA biology to the understanding of the normal and pathological physiology of the TM, and to develop novel clinical applications for diagnosis and therapy of high intraocular pressure.

Endogenous production of extracellular adenosine by trabecular meshwork cells: potential role in outflow regulation.

PURPOSE: To investigate the mechanisms for endogenous production of extracellular adenosine in trabecular meshwork (TM) cells and evaluate its physiological relevance to the regulation of aqueous humor outflow facility. METHODS: Extra-cellular levels of adenosine monophosphate (AMP) and adenosine in porcine trabecular meshwork (PTM) cells treated with adenosine triphosphate (ATP), AMP, cAMP or forskolin with or without specific inhibitors of phosphodiesterases (IBMX) and CD73 (AMPCP) were determined by high-pressure liquid chromatography fluorometry. Extracellular adenosine was also evaluated in cell cultures subjected to cyclic mechanical stress (CMS) (20% stretching; 1 Hz) and after disruption of lipid rafts with methyl-ß-cyclodextrin. Expression of CD39 and CD73 in porcine TM cells and tissue were examined by Q-PCR and Western blot. The effect of inhibition of CD73 on outflow facility was evaluated in perfused living mouse eyes. RESULTS: PTM cells generated extracellular adenosine from extracellular ATP and AMP but not from extracellular cAMP. Increased intracellular cAMP mediated by forskolin led to a significant increase in extracellular adenosine production that was not prevented by IBMX. Inhibition of CD73 resulted, in all cases, in a significant decrease in extracellular adenosine. CMS induced a significant activation of extracellular adenosine production. Inhibition of CD73 activity with AMPCP in living mouse eyes resulted in a significant decrease in outflow facility. CONCLUSIONS: These results support the concept that the extracellular adenosine pathway might play an important role in the homeostatic regulation of outflow resistance in the TM, and suggest a novel mechanism by which pathologic alteration of the TM, such as increased tissue rigidity, could lead to abnormal elevation of IOP in glaucoma.