Eye / Vision
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/30810
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Browsing Eye / Vision by Author "Stankowska, Dorota"
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Item Changes in the Expression of SMARCA4 in a Rat Model of Ocular Hypertension(2022) Worley, Josh; Stankowska, Dorota; Kodati, Bindu; Krishnamoorthy, RaghuTitle: Changes in the Expression of SMARCA4 in a Rat Model of Ocular Hypertension Purpose: SMARC4 (BRG1) is an ATP-dependent chromatin remodeling protein belonging to the SWI/SNF family of proteins involved in regulation of gene expression in numerous cell types in the body. The purpose of this study was to determine changes in the expression of SMARCA4 in the retina following intraocular pressure (IOP) elevation by the Morrison model in Brown Norway rats. We hypothesize that SMARCA4 expression may modulate the expression of the key genes involved in the neurodegenerative changes seen secondary to IOP elevation. Methods: The Morrison model of ocular hypertension (by injection of hypertonic saline through the episcleral veins) was utilized to unilaterally elevate the IOP in Brown Norway rats. IOP was elevated in the left eye of three retired breeder Brown Norway rats, with the right eye serving as the corresponding contralateral control. Rats were maintained for 2 weeks following IOP elevation and IOP measurements were carried out twice per week. Rats were subsequently euthanized, and retinal sections were obtained from both IOP-elevated and contralateral control eyes. Immunohistochemical analysis of SMARCA4 expression was carried out by immunostaining. Following confocal microscopy imaging, the intensity of immunofluorescence was quantified with the ImageJ software (NIH), and compared between IOP elevated and control eyes. Results: Immunohistochemical analysis revealed an appreciable decrease in the expression of SMARCA4 in retinal sections in two out of three rats, mainly the nerve fiber layer (by 47 to 57%), ganglion cell layer (by 18 to 40%) and inner plexiform layer (by 9 to 19%) in IOP elevated rat eyes compared to control eyes. One out of three tested rats showed a modest increase in immunostaining for SMARCA4 in the nerve fiber layer, ganglion cell layer and inner plexiform layer. Ongoing experiments will replicate these findings in order to generate statistically significant data. Conclusion: Changes in SMARCA4 expression could serve to regulate the expression of gene contributing to neurodegenerative effects due to elevated IOP. Understanding the role of SMARCA4 may allow us to better understand and address the mechanisms involved in glaucomatous neurodegeneration.Item Hybrid molecule SA-2 improves both mitochondrial respiration and glycolysis in primary human trabecular meshwork cells(2022) Amankwa, Charles E.; Gondi, Sudershan; Stankowska, Dorota; Acharya, SuchismitaPurpose: Oxidative stress (OS) caused by hypoxia/hyperoxia environment results in progressive loss of trabecular meshwork (TM) cells in primary open angle glaucoma (POAG). Our previous report demonstrated; a hybrid nitric oxide (NO) donor-antioxidant molecule SA-2 protect primary human (h) TM cells against t-butyl hydrogen peroxide (TBHP) -induced cell death and increased superoxide dismutase enzyme level. Here we investigated the effect of SA-2 on mitochondrial energy metabolism by measuring the respiration status, glycolysis rate and energy production. Methods: Primary hTM cells obtained from human donor eyes were seeded in 24-well culture plates (Seahorse XFe 24 Cell Mito Stress test kit, Agilent), and starved for 24h before treatment with SA-2 (1 µM,10µM,100µM, and 1mM). In a separate experiment, the cells were pretreated with TBHP (150µM) for 30 minutes, followed by the addition of SA-2 (10µM,100µM). After 24h, the mitochondrial complex inhibitors and uncoupling reagents (oligomycin, FCCP, rotenone/antimycin A) were added. The plate was analyzed for changes in oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) using the Seahorse XFe24 analyzer following the manufacturer's instructions. Results: The mean OCR was significantly decreased (>70%) followed by increase in the mean ECAR (~3-fold) after treatment with TBHP compared to oligo/FCCP/rot treated cells, hereafter called as negative control. Treatment with SA-2 at 1 µM,10µM,100µM and 1mM concentrations increased both oligomycin/FCCP induced decrease in ATP production and maximal mitochondrial respiration followed by an increase in the mean ECAR compared to negative control. The mean OCR was higher in SA-2 (100µM) +TBHP treated cells followed by an increase in ECAR in SA-2 (10µM or 100µM) +TBHP treated cells than TBHP and negative control treated cells. N =2-3. Conclusion: Mitochondrial respiration was impaired after TBHP treatment to hTM cells following cell death. While most of the mitochondrial targeting anti-oxidant compounds increase OCR but not ECAR, we found the hybrid NO donor-anti-oxidant compound SA-2 increases ATP production, maximal mitochondrial respiration and increases glycolytic energy production in hTM cells. This finding provides a novel direction for further investigation into the effect of SA-2 and mitochondrial bioenergetics during OS-induced cell death.Item Mechanisms of peptain-mediated neuroprotection in retinal ganglion cells(2022) Johnson, Gretchen A.; Pham, Jennifer; Kodati, Bindu; Krishnamoorthy, Raghu; Nagaraj, Ram; Stankowska, DorotaPURPOSE: To determine mechanisms underlying neuroprotective effects of the core peptide of alpha-B crystallin, peptain-1 (P1) conjugated to a cell-permeable peptide CPP (P1-CPP) in retinal ganglion cells (RGCs) in a rodent model of glaucoma. METHODS: Intraocular pressure (IOP) was elevated in Brown Norway (BN) rats and intravitreally injected with 2 µl of either P1-CPP or vehicle, once a week for a period of 2 weeks. Rats were euthanized, primary adult RGCs were isolated by the immunopanning method. Total RNA was isolated using the Trizol/column method. RNA-sequencing was performed using an Illumina platform. The resulting FASTQ files were uploaded into Galaxy for analysis with FASTQC, RNASTAR, feature counts, and finally DESeq2. The results from DESeq2 were then assessed with Qiagen's Ingenuity Pathway Analysis (IPA) to identify significantly upregulated pathways. Relative Creb-1 expression normalized to reference gene GAPDH was determined in IOP-P1-CPP and IOP-vehicle treated rat RGCs. Briefly, quantitative Polymerase Chain Reaction (qPCR) was performed using BioRad's PrimePCR Assay and SsoAdvanced Universal SYBR Green Supermix on the BioRad's CFX96 Real-Time System C1000 Touch Thermal Cycler. RESULTS: RNA-seq analysis from rat RGCs isolated following 2 weeks of IOP-elevation revealed that P1-CPP treated groups had several differentially expressed (DEGs), compared to vehicle-treated groups, including 6343 significantly upregulated and 5960 significantly downregulated. Some significantly upregulated pathways following P1-CPP treatment include phagosome formation, synaptic long-term depression, and CREB signaling in neurons. The IOP and vehicle-treated groups, when compared to the naïve group, demonstrated a decreased expression of members of the CREB signaling pathway (Creb-1, c-RAF, MEK1/2, ERK1/2, and p90RSK). This decline was prevented by P1-CPP treatment. Quantitative PCR further confirmed the RNA-seq findings of the increased expression of Creb-1 in P1-CPP treated rats compared to that of vehicle-treated group. CONCLUSIONS: Mechanism of action of P1-CPP in a rodent model of glaucoma includes the activation of the pro-survival CREB signaling pathway, phagosome formation, and long-term synaptic depression to prevent cell death and vision loss.Item Neuroprotection of human and rodent retinal ganglion cells by a hybrid antioxidant-nitric oxide donor small molecule, SA-2(2022) Pham, Jennifer; Johnson, Gretchen A.; Acharya, Suchismita; Stankowska, DorotaPURPOSE: Current treatments of glaucoma are aimed at lowering intraocular pressure (IOP), which is a key driver of retinal ganglion cell (RGC) death. Another contributing factor to RGC death is exposure to reactive oxygen species (ROS). At present, there is no FDA-approved neuroprotective treatment to prevent glaucomatous optic neuropathy and loss of RGCs. Our novel hybrid molecule, SA-2, contains both a nitric oxide (NO) donating group to lower IOP and a ROS scavenging group to protect RGCs. We hypothesize that SA-2 will inhibit the death of RGCs in an in vitro and an ex vivo neurotrophic factor deprivation model. METHODS: Retinal punches from human explants (n=4 donors/experiments) were isolated and treated with either SA-2 [1 mM] or vehicle and maintained without neurotrophic factors for 7 days ex vivo. In each experiment, 4 baseline retinal explants were collected on day 0. At the end of the experiment, explants were immunostained with RBPMS and Brn-3a (RGC-specific markers) and cell survival was analyzed. In three biological replicates, primary RGCs were isolated from rat pups and treated with either SA-2 (1 mM, 100 µM) or vehicle with or without neurotrophic factors for 48 h. Active caspase 3 and 7 assay was performed and apoptotic cell counts were analyzed. In another set of experiments, rat retinal explants were isolated and incubated with tert-Butyl hydroperoxide (TBHP) along with either SA-2 [1 mM] or vehicle for 2 h (n=2-4 explants/group). Production of superoxide by mitochondria was assessed using MitoSOX reagent according to manufacturer instructions. All cell counts were performed in a masked manner using ImageJ Software. One-way ANOVA or nonparametric Kruskal-Wallis was used for statistical analysis by GraphPad Prism 9 Software. RESULTS: In ex vivo human retinal explants, there was a significant increase in RGC survival by 39% in the SA-2 treated group compared to the vehicle group at day 7 (p< 0.0001). In rodent primary RGCs, SA-2 mediated a significant decrease in apoptotic cells by 30% (p< 0.01) and a 67% (p< 0.05) decrease in dead cell count. In rodent retinal explants, there was a significant decrease (by 59%, p< 0.0001) in the production of superoxide by mitochondria in the TBHP and SA-2 treated group, compared to the TBHP vehicle group. CONCLUSION: SA-2 was shown to be effective at preserving retinal ganglion cell survival in human retinal explants, rat retinal explants and primary rat RGCs by preventing apoptosis and protecting the cells from oxidative stress.