miR-17-3p Exacerbates Oxidative Damage in Human Retinal Pigment Epithelial Cells

MiR-17-3p Facilitates Aggressive Cell Phenotypes in Colon Cancer by Targeting PLCD1 Through Affecting KIF14

Colon cancer (CC) is a common and lethal cancer to be further elucidated. Accumulating studies elaborated the crucial role of miRNAs differentially expressed in cancer cell growth. In the present study, differentially expressed miRNAs related to CC were screened by the bioinformatics methods on the strength of TCGA database. Highly expressed miR-17-3p was proved to notably influence CC cell proliferative, migratory, invasion, and apoptotic levels. By using TargetScan and miRTarBase databases, phospholipase C delta 1 (PLCD1) was predicted as a target downstream of miR-17-3p, and their binding site was predicted. Through TCGA database, low expression of PLCD1 and its significant negative correlation with miR-17-3p were identified in CC. Dual-luciferase reporter gene analysis ascertained the targeting relationship between miR-17-3p and PLCD1. Cell Counting Kit-8, colony formation, and transwell assays were introduced to detect CC cell malignant progression. Flow cytometry was applied to detect CC cell apoptosis. As result revealed, miR-17-3p was markedly highly expressed, and PLCD1, the target of miR-17-3p, was remarkably lowly expressed in CC cells. Forced expression of miR-17-3p facilitated CC cell proliferation, migration, invasion, and suppressed apoptosis. Biological roles of upregulating miR-17-3p in the colon cancer cells were markedly weakened by over-expressing PLCD1 simultaneously. MiR-17-3p regulated CC cell malignant progression, as well as apoptosis by targeting PLCD1. Moreover, KIF14 was extensively considered as an involved tumor-promoting gene that could be affected by miR-17-3p/PLCD1 axis based on BioGRID analysis and CO-IP assay. Concludingly, this study exhibited that miR-17-3p facilitated CC progression by PLCD1 downregulation.

MiR-302d inhibits TGFB-induced EMT and promotes MET in primary human RPE cells

PURPOSE

Transforming growth factor-beta (TGFB)-mediated epithelial-mesenchymal transition (EMT) plays a crucial role in the pathogenesis of retinal fibrosis, which is one of the leading causes of impaired vision. Current approaches to treating retinal fibrosis focus, among other things, on inhibiting the TGFB signaling pathway. Transient expression of microRNAs (miRNAs) is one way to inhibit the TGFB pathway post-transcriptionally. Our previous study identified the miRNA miR-302d as a regulator of multiple TGFB-related genes in ARPE-19 cells. To further explore its effect on primary cells, the effect of miR-302d on TGFB-induced EMT in primary human retinal pigment epithelium (hRPE) was investigated in vitro.

METHODS

hRPE cells were extracted from patients receiving enucleation. Transfection of hRPE cells with miR-302d was performed before or after TGFB1 stimulation. Live-cell imaging, immunocytochemistry staining, Western blot, and ELISA assays were utilized to identify the alterations of cellular morphology and EMT-related factors expressions in hRPE cells.

RESULTS

hRPE cells underwent EMT by TGFB1 exposure. The transfection of miR-302d inhibited the transition with decreased production of mesenchymal markers and increased epithelial factors. Meanwhile, the phosphorylation of SMAD2 activated by TGFB1 was suppressed. Moreover, miR-302d expression promoted TGFB1-induced fibroblast-like hRPE cells to revert towards an epithelial stage. As confirmed by ELISA, miR-302d reduced TGFB receptor 2 (TGFBR2) and vascular endothelial growth factor A (VEGFA) levels 48 hours after transfection.

CONCLUSIONS

The protective effect of miR-302d might be a promising approach for ameliorating retinal fibrosis and neovascularization. MiR-302d suppresses TGFB-induced EMT in hRPE cells via downregulation of TGFBR2, even reversing the process. Furthermore, miR-302d reduces the constitutive secretion of VEGFA from hRPE cells.

Hormesis and Oxidative Distress: Pathophysiology of Reactive Oxygen Species and the Open Question of Antioxidant Modulation and Supplementation

Alterations of redox homeostasis leads to a condition of resilience known as hormesis that is due to the activation of redox-sensitive pathways stimulating cell proliferation, growth, differentiation, and angiogenesis. Instead, supraphysiological production of reactive oxygen species (ROS) exceeds antioxidant defence and leads to oxidative distress. This condition induces damage to biomolecules and is responsible or co-responsible for the onset of several chronic pathologies. Thus, a dietary antioxidant supplementation has been proposed in order to prevent aging, cardiovascular and degenerative diseases as well as carcinogenesis. However, this approach has failed to demonstrate efficacy, often leading to harmful side effects, in particular in patients affected by cancer. In this latter case, an approach based on endogenous antioxidant depletion, leading to ROS overproduction, has shown an interesting potential for enhancing susceptibility of patients to anticancer therapies. Therefore, a deep investigation of molecular pathways involved in redox balance is crucial in order to identify new molecular targets useful for the development of more effective therapeutic approaches. The review herein provides an overview of the pathophysiological role of ROS and focuses the attention on positive and negative aspects of antioxidant modulation with the intent to find new insights for a successful clinical application.

MicroRNA-17-3p suppresses NF-κB-mediated endothelial inflammation by targeting NIK and IKKβ binding protein

Nuclear factor kappa B (NF-κB) activation contributes to many vascular inflammatory diseases. The present study tested the hypothesis that microRNA-17-3p (miR-17-3p) suppresses the pro-inflammatory responses via NF-κB signaling in vascular endothelium. Human umbilical vein endothelial cells (HUVECs), transfected with or without miR-17-3p agomir/antagomir, were exposed to lipopolysaccharide (LPS), and the inflammatory responses were determined. The cellular target of miR-17-3p was examined with dual-luciferase reporter assay. Mice were treated with miR-17-3p agomir and the degree of LPS-induced inflammation was determined. In HUVECs, LPS caused upregulation of miR-17-3p. Overexpression of miR-17-3p in HUVECs inhibited NIK and IKKβ binding protein (NIBP) protein expression and suppressed LPS-induced phosphorylation of inhibitor of kappa Bα (IκBα) and NF-κB-p65. The reduced NF-κB activity was paralleled by decreased protein levels of NF-κB-target gene products including pro-inflammatory cytokine [interleukin 6], chemokines [interleukin 8 and monocyte chemoattractant protein-1] and adhesion molecules [vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin]. Immunostaining revealed that overexpression of miR-17-3p reduced monocyte adhesion to LPS-stimulated endothelial cells. Inhibition of miR-17-3p with antagomir has the opposite effect on LPS-induced inflammatory responses in HUVECs. The anti-inflammatory effect of miR-17-3p was mimicked by NIBP knockdown. In mice treated with LPS, miR-17-3p expression was significantly increased. Systemic administration of miR-17-3p for 3 days suppressed LPS-induced NF-κB activation and monocyte adhesion to endothelium in lung tissues of the mice. In conclusion, miR-17-3p inhibits LPS-induced NF-κB activation in HUVECs by targeting NIBP. The findings therefore suggest that miR-17-3p is a potential therapeutic target/agent in the management of vascular inflammatory diseases.

Circular RNAs; powerful microRNA sponges to overcome diabetic nephropathy

Diabetic nephropathy (DN), also known as diabetic kidney disease (DKD), is a drastic renal complication of type 1 and type 2 diabetes mellitus (DM). Poorly controlled DM over the years, may disrupt kidneys' blood vessels, leading to the hypertension (HTN) and DN onset. During DN, kidneys' waste filtering ability becomes disturbed. Being on a healthy lifestyle and controlling both DM and HTN are now the best proceedings to prevent or at least delay DN occurrence. Unfortunately, about one-fourth of diabetic individuals eventually experience the corresponding renal failure, and thus it is critical to discover effective diagnostic biomarkers and therapeutic strategies to combat DN. In the past few years, circular RNAs (circRNAs), as covalently closed endogenous non-coding RNAs (ncRNAs), are believed to affect DN pathogenesis in a positive manner. CircRNAs are able to impact different cellular processes and signaling pathways by targeting biological molecules or various molecular mechanisms. Still, as a key regulatory axis, circRNAs can select miRNAs as their molecular targets, in which they are considered as miRNA sponges. In this way, circRNA-induced suppression of particular miRNAs may prevent from DN progression or promotes the DN elimination. Since the expression of circRNAs has also been reported to be increased in DN-associated cells and tissues, they can be employed as either diagnostic biomarkers or therapeutic targets.

Micro RNAs in Regulation of Cellular Redox Homeostasis

In living cells Reactive Oxygen Species (ROS) participate in intra- and inter-cellular signaling and all cells contain specific systems that guard redox homeostasis. These systems contain both enzymes which may produce ROS such as NADPH-dependent and other oxidases or nitric oxide synthases, and ROS-neutralizing enzymes such as catalase, peroxiredoxins, thioredoxins, thioredoxin reductases, glutathione reductases, and many others. Most of the genes coding for these enzymes contain sequences targeted by micro RNAs (miRNAs), which are components of RNA-induced silencing complexes and play important roles in inhibiting translation of their targeted messenger RNAs (mRNAs). In this review we describe miRNAs that directly target and can influence enzymes responsible for scavenging of ROS and their possible role in cellular redox homeostasis. Regulation of antioxidant enzymes aims to adjust cells to survive in unstable oxidative environments; however, sometimes seemingly paradoxical phenomena appear where oxidative stress induces an increase in the levels of miRNAs which target genes which are supposed to neutralize ROS and therefore would be expected to decrease antioxidant levels. Here we show examples of such cellular behaviors and discuss the possible roles of miRNAs in redox regulatory circuits and further cell responses to stress.

Molecular Mechanisms Related to Oxidative Stress in Retinitis Pigmentosa

Retinitis pigmentosa (RP) is an inherited retinopathy. Nevertheless, non-genetic biological factors play a central role in its pathogenesis and progression, including inflammation, autophagy and oxidative stress. The retina is particularly affected by oxidative stress due to its high metabolic rate and oxygen consumption as well as photosensitizer molecules inside the photoreceptors being constantly subjected to light/oxidative stress, which induces accumulation of ROS in RPE, caused by damaged photoreceptor’s daily recycling. Oxidative DNA damage is a key regulator of microglial activation and photoreceptor degeneration in RP, as well as mutations in endogenous antioxidant pathways involved in DNA repair, oxidative stress protection and activation of antioxidant enzymes (MUTYH, CERKL and GLO1 genes, respectively). Moreover, exposure to oxidative stress alters the expression of micro-RNA (miRNAs) and of long non-codingRNA (lncRNAs), which might be implicated in RP etiopathogenesis and progression, modifying gene expression and cellular response to oxidative stress. The upregulation of the P2X7 receptor (P2X7R) also seems to be involved, causing pro-inflammatory cytokines and ROS release by macrophages and microglia, contributing to neuroinflammatory and neurodegenerative progression in RP. The multiple pathways analysed demonstrate that oxidative microglial activation may trigger the vicious cycle of non-resolved neuroinflammation and degeneration, suggesting that microglia may be a key therapy target of oxidative stress in RP.

The Impact of miRNAs in Health and Disease of Retinal Pigment Epithelium

MicroRNAs (miRNAs), a class of non-coding RNAs, are essential key players in the control of biological processes in both physiological and pathological conditions. miRNAs play important roles in fine tuning the expression of many genes, which often have roles in common molecular networks. miRNA dysregulation thus renders cells vulnerable to aberrant fluctuations in genes, resulting in degenerative diseases. The retinal pigment epithelium (RPE) is a monolayer of polarized pigmented epithelial cells that resides between the light-sensitive photoreceptors (PR) and the choriocapillaris. The demanding physiological functions of RPE cells require precise gene regulation for the maintenance of retinal homeostasis under stress conditions and the preservation of vision. Thus far, our understanding of how miRNAs function in the homeostasis and maintenance of the RPE has been poorly addressed, and advancing our knowledge is central to harnessing their potential as therapeutic agents to counteract visual impairment. This review focuses on the emerging roles of miRNAs in the function and health of the RPE and on the future exploration of miRNA-based therapeutic approaches to counteract blinding diseases.

Crocetin Prevents RPE Cells from Oxidative Stress through Protection of Cellular Metabolic Function and Activation of ERK1/2

Age-related macular degeneration (AMD) is a leading cause for visual impairment in aging populations with limited established therapeutic interventions available. Oxidative stress plays an essential role in the pathogenesis of AMD, damaging the retinal pigment epithelium (RPE), which is essential for the function and maintenance of the light-sensing photoreceptors. This study aimed to evaluate the effects of crocetin, one of the main components of Saffron, on an in vitro RPE model of tert-butyl hydroperoxide (TBHP) induced oxidative stress using ARPE19 cells. The effects of crocetin were assessed using lactate de-hydrogenase (LDH) and ATP assays, as well as immunocytochemistry for cell morphology, junctional integrity, and nuclear morphology. The mechanism of crocetin action was determined via assessment of energy production pathways, including mitochondrial respiration and glycolysis in real-time as well as investigation of extracellular signal-regulated kinase 1/2 (ERK1/2) activation and distribution. Our results show that crocetin pre-treatment protects ARPE19 cells from TBHP-induced LDH release, intracellular ATP depletion, nuclear condensation, and disturbance of junctional integrity and cytoskeleton. The protective effect of crocetin is mediated via the preservation of energy production pathways and activation of ERK1/2 in the first minutes of TBHP exposure to potentiate survival pathways. The combined data suggest that a natural antioxidant, such as crocetin, represents a promising candidate to prevent oxidative stress in RPE cells and might halt or delay disease progression in AMD.

miR302a and 122 are deregulated in small extracellular vesicles from ARPE-19 cells cultured with H2O2

Age related macular degeneration (AMD) is a common retina-related disease leading to blindness. Little is known on the origin of the disease, but it is well documented that oxidative stress generated in the retinal pigment epithelium and choroid neovascularization are closely involved. The study of circulating miRNAs is opening new possibilities in terms of diagnosis and therapeutics. miRNAs can travel associated to lipoproteins or inside small Extracellular Vesicles (sEVs). A number of reports indicate a significant deregulation of circulating miRNAs in AMD and experimental approaches, but it is unclear whether sEVs present a significant miRNA cargo. The present work studies miRNA expression changes in sEVs released from ARPE-19 cells under oxidative conditions (i.e. hydrogen peroxide, H₂O₂). H₂O₂ increased sEVs release from ARPE-19 cells. Moreover, 218 miRNAs could be detected in control and H₂O₂ induced-sEVs. Interestingly, only two of them (hsa-miR-302a and hsa-miR-122) were significantly under-expressed in H₂O₂-induced sEVs. Results herein suggest that the down regulation of miRNAs 302a and 122 might be related with previous studies showing sEVs-induced neovascularization after oxidative challenge in ARPE-19 cells.

miR-19a Is Involved In Progression And Malignancy Of Anaplastic Thyroid Cancer Cells

Background

MicroRNAs (miRNAs) are endogenous, single-stranded, non-coding RNAs acting as negative regulators of gene expression involved in a number of physiological processes. MiRNAs' expression is commonly dysregulated in many types of human tumor diseases and cancers, including thyroid cancers, and is often involved in tumor initiation and progression. miR-19a, a member of miR-17-92 cluster, has been demonstrated to promote cell growth in anaplastic thyroid cancer (ATC), the most advanced and aggressive thyroid cancer.

Purpose

In this work, we investigate the potential contribution of miR-19a in thyroid cancer cells poor prognosis and de-differentiation.

Methods

We directly modulated the expression of miR-19a in papillary (PTC) and anaplastic thyroid carcinoma cell lines through transfection of specific miR-19a mimic or inhibitor. Further, we performed gene expression analysis of specific genes to evaluate miR-19a association with cell cycle, differentiation, and poor prognosis.

Results

Our data indicate that miR-19a overexpression in PTC cells significantly promotes cell growth, decreases the expression of differentiation genes and activates poor prognosis genes. Its inhibition in ATC cells reduces cell proliferation and the expression of genes related to poor prognosis but does not affect differentiation.

Conclusion

Our findings reveal the existence of functional associations between miR-19a expression and thyroid cancer progression and malignancy suggesting miR-19a as a novel candidate therapeutic target for ATC.

MiR-21-3p modulates lipopolysaccharide-induced inflammation and apoptosis via targeting TGS4 in retinal pigment epithelial cells

Age-related macular degeneration (AMD) is a major reason of blindness in the elderly. MicroRNAs are implicated in various pathological processes, including inflammation and apoptosis. In this study, we aim to investigate the biological functions of miR-21-3p in inflammation and apoptosis caused by lipopolysaccharide (LPS) in human retinal pigment epithelial (ARPE-19) cells. The miR-21-3p inhibitor and mimic were transfected into ARPE-19 cells for 48 hours, followed by exposed to LPS (10 μg/mL) for 24 hours. The mRNA and protein expression of IL-6 and MCP-1 were measured using real-time PCR (RT-PCR) and enzyme-linked immunosorbent assays. Cell viability, apoptosis, caspase 3 activity, cleaved caspase-3 and cleaved-PARP protein levels were detected to evaluate the effects of miR-21-3p on apoptosis. Additionally, the target relationship between miR-21-3p and regulator of G-protein signalling 4 (RGS4) was verified by dual luciferase reporter assay. RT-PCR analysis demonstrated that LPS induced miR-21-3p expression. Inhibition of miR-21-3p reduced the mRNA and protein levels of IL-6 and MCP-1. Apoptosis, caspase-3 activity, and cleaved-caspase 3 and cleaved PARP protein levels were repressed by the miR-21-3p inhibitor. However, overexpression of miR-21-3p showed the opposite results. Furthermore, we identified that miR-21-3p directly targeted the 3' untranslated region of RGS4. MiR-21-3p negatively regulated the expression of RGS4 both in mRNA and protein levels. Silencing RGS4 reduced the anti-inflammatory and anti-apoptotic effects of miR-21-3p inhibitor. Our results revealed that miR-21-3p inhibition targeted RGS4 to attenuate inflammatory responses and apoptosis caused by LPS in ARPE-19 cells.

miR-17-3p Downregulates Mitochondrial Antioxidant Enzymes and Enhances the Radiosensitivity of Prostate Cancer Cells

Radioresistance remains to be a major obstacle in the management of patients with advanced prostate cancer (PCa). We have identified a mature miR-17-3p processed from the 3' arm of precursor miR-17, which appeared to be able to inhibit three major antioxidant enzymes located in mitochondria, i.e., manganese superoxide dismutase (MnSOD), glutathione peroxidase 2 (Gpx2), and thioredoxin reductase 2 (TrxR2). Here we show that upregulation of miR-17-3p remarkably sensitized PCa cells to ionizing radiation (IR). Reductions of the three antioxidants led to increasing cellular reactive oxygen species (ROS) accumulation as well as declining mitochondrial respiration. The miR-17-3p-mediated dysfunction of mitochondrial antioxidants apparently sensitizing IR therapy was manifested in vitro and in vivo. Substantially, the miR-17-3p effect on suppression of the antioxidants can be efficiently eliminated or attenuated by transfecting with either an miR-17-3p inhibitor or each of the related antioxidant cDNA expression constructs. Overall, in addition to the insights into the functional assessments for the duplex of miR-17-5p and miR-17-3p, the present study highlights the rigorous evidence that demonstrated suppression of multiple mitochondrial antioxidants by a single microRNA (miRNA), thereby providing a promising approach to improve radiotherapy for advanced PCa by targeting mitochondrial function.

Beneficial and paradoxical roles of selenium at nutritional levels of intake in healthspan and longevity

Accumulation of genome and macromolecule damage is a hallmark of aging, age-associated degeneration, and genome instability syndromes. Although processes of aging are irreversible, they can be modulated by genome maintenance pathways and environmental factors such as diet. Selenium (Se) confers its physiological functions mainly through selenoproteins, but Se compounds and other proteins that incorporate Se nonspecifically also impact optimal health. Bruce Ames proposed that the aging process could be mitigated by a subset of low-hierarchy selenoproteins whose levels are preferentially reduced in response to Se deficiency. Consistent with this notion, results from two selenotranscriptomic studies collectively implicate three low-hierarchy selenoproteins in age or senescence. Experimental evidence generally supports beneficial roles of selenoproteins in the protection against damage accumulation and redox imbalance, but some selenoproteins have also been reported to unexpectedly display harmful functions under sporadic conditions. While longevity and healthspan are usually thought to be projected in parallel, emerging evidence suggests a trade-off between longevity promotion and healthspan deterioration with damage accumulation. We propose that longevity promotion under conditions of Se deficiency may be attributed to 1) stress-response hormesis, an advantageous event of resistance to toxic chemicals at low doses; 2) reduced expression of selenoproteins with paradoxical functions to a lesser extent. In particular, selenoprotein H is an evolutionally conserved nuclear selenoprotein postulated to confer Se functions in redox regulation, genome maintenance, and senescence. This review highlights the need to pinpoint roles of specific selenoproteins and Se compounds in healthspan and lifespan for a better understanding of Se contribution at nutritional levels of intake to healthy aging.

Redox Regulation and Noncoding RNAs

SIGNIFICANCE

RNA is a heterogeneous class of molecules with the minority being protein coding. Noncoding RNAs (ncRNAs) are involved in translation and epigenetic control mechanisms of gene expression. Recent Advances: In recent years, the number of identified ncRNAs has dramatically increased and it is now clear that ncRNAs provide a complex layer of differential gene expression control.

CRITICAL ISSUES

NcRNAs exhibit interplay with redox regulation. Redox regulation alters the expression of ncRNAs; conversely, ncRNAs alter the expression of generator and effector systems of redox regulation in a complex manner, which will be the focus of this review article.

FUTURE DIRECTIONS

Understanding the role of ncRNA in redox control will lead to the development of new strategies to alter redox programs. Given that many ncRNAs (particularly microRNAs [miRNAs]) change large gene sets, these molecules are attractive drug candidates; already, now miRNAs can be targeted in patients. Therefore, the development of ncRNA therapies focusing on these molecules is an attractive future strategy. Antioxid. Redox Signal. 29, 793-812.

Hepatic oxidative stress in pigmented P23H rhodopsin transgenic rats with progressive retinal degeneration

Retinitis pigmentosa (RP) comprises a group of inherited retinal degenerative conditions characterized by primary degeneration of the rod photoreceptors. Increased oxidative damage is observed in the retina, aqueous humor, and plasma of RP animal models and patients. The hepatic oxidative status may also be affected in RP due to oxidative damage influencing soluble macromolecules exiting the retina or to alterations in the melanopsin system resulting in chronic circadian desynchronization that negatively alters the oxidative stress defense system. P23H rats were crossed with pigmented Long Evans rats to produce offspring exhibiting the clinical conditions of RP. We measured hepatic malondialdehyde and 4-hydroxyalkenal concentrations as oxidative stress markers; nitrite level as a total nitrosative damage marker; total antioxidant capacity; and the activities of catalase, superoxide dismutase (SOD), and glutathione S-transferase. Retinal visual function was assessed based on optomotor and electroretinogram responses. P23H transgenic rats exhibited diminished visual acuity, contrast sensitivity, and electroretinographic responses according to the level of retinal degeneration. P23H rats at 30 days of age already demonstrated only 47% of the hepatic total antioxidant capacity of wild-type animals. Hepatic catalase and SOD activities were also reduced in P23H rats after 120 days, but we detected no difference in glutathione S-transferase activity. P23H rats had increased hepatic oxidative and nitrosative damage markers. GSH/GSSG ratio showed a significant diminution in P23H rats at P120 compared to WT. We conclude that the liver is under increased oxidative stress in P23H rats. Further studies are required, however, to clarify the contribution of systemic oxidative damage to the pathogenesis of RP.

Neuroprotection afforded by circadian regulation of intracellular glutathione levels: A key role for miRNAs

Circadian rhythms are approximately 24-h oscillations of physiological and behavioral processes that allow us to adapt to daily environmental cycles. Like many other biological functions, cellular redox status and antioxidative defense systems display circadian rhythmicity. In the central nervous system (CNS), glutathione (GSH) is a critical antioxidant because the CNS is extremely vulnerable to oxidative stress; oxidative stress, in turn, causes several fatal diseases, including neurodegenerative diseases. It has long been known that GSH level shows circadian rhythm, although the mechanism underlying GSH rhythm production has not been well-studied. Several lines of recent evidence indicate that the expression of antioxidant genes involved in GSH homeostasis as well as circadian clock genes are regulated by post-transcriptional regulator microRNA (miRNA), indicating that miRNA plays a key role in generating GSH rhythm. Interestingly, several reports have shown that alterations of miRNA expression as well as circadian rhythm have been known to link with various diseases related to oxidative stress. A growing body of evidence implicates a strong correlation between antioxidative defense, circadian rhythm and miRNA function, therefore, their dysfunctions could cause numerous diseases. It is hoped that continued elucidation of the antioxidative defense systems controlled by novel miRNA regulation under circadian control will advance the development of therapeutics for the diseases caused by oxidative stress.

Dissecting microRNA dysregulation in age-related macular degeneration: new targets for eye gene therapy

MicroRNAs (miRNAs) are key regulators of gene expression in humans. Overexpression or depletion of individual miRNAs is associated with human disease. Current knowledge suggests that the retina is influenced by miRNAs and that dysregulation of miRNAs as well as alterations in components of the miRNA biogenesis machinery are involved in retinal diseases, including age-related macular degeneration (AMD). Furthermore, recent studies have indicated that the vitreous has a specific panel of circulating miRNAs and that this panel varies according to the specific pathological stress experienced by the retinal cells. MicroRNA (miRNA) profiling indicates subtype-specific miRNA profiles for late-stage AMD highlighting the importance of proper miRNA regulation in AMD. This review will describe the function of important miRNAs involved in inflammation, oxidative stress and pathological neovascularization, the key molecular mechanisms leading to AMD, and focus on dysregulated miRNAs as potential therapeutic targets in AMD.

Epigenetic Treatment of Neurodegenerative Ophthalmic Disorders: An Eye Toward the Future

Eye disease is one of the primary medical conditions that requires attention and therapeutic intervention in ageing populations worldwide. Further, the global burden of diabetes and obesity, along with heart disease, all lead to secondary manifestations of ophthalmic distress. Therefore, there is increased interest in developing innovative new approaches that target various mechanisms and sequelae driving conditions that result in adverse vision. The research challenge is even greater given that the terrain of eye diseases is difficult to landscape into a single therapeutic theme. This report addresses the burden of eye disease due to mitochondrial dysfunction, including antioxidant, autophagic, epigenetic, mitophagic, and other cellular processes that modulate the biomedical end result. In this light, we single out lipoic acid as a potent known natural activator of these pathways, along with alternative and potentially more effective conjugates, which together harness the necessary potency, specificity, and biodistribution parameters required for improved therapeutic outcomes.

Multimodal Regulation Orchestrates Normal and Complex Disease States in the Retina

Regulation of biological processes occurs through complex, synergistic mechanisms. In this study, we discovered the synergistic orchestration of multiple mechanisms regulating the normal and diseased state (age related macular degeneration, AMD) in the retina. We uncovered gene networks with overlapping feedback loops that are modulated by nuclear hormone receptors (NHR), miRNAs, and epigenetic factors. We utilized a comprehensive filtering and pathway analysis strategy comparing miRNA and microarray data between three mouse models and human donor eyes (normal and AMD). The mouse models lack key NHRS (Nr2e3, RORA) or epigenetic (Ezh2) factors. Fifty-four total miRNAs were differentially expressed, potentially targeting over 150 genes in 18 major representative networks including angiogenesis, metabolism, and immunity. We identified sixty-eight genes and 5 miRNAS directly regulated by NR2E3 and/or RORA. After a comprehensive analysis, we discovered multimodal regulation by miRNA, NHRs, and epigenetic factors of three miRNAs (miR-466, miR1187, and miR-710) and two genes (Ell2 and Entpd1) that are also associated with AMD. These studies provide insight into the complex, dynamic modulation of gene networks as well as their impact on human disease, and provide novel data for the development of innovative and more effective therapeutics.