Roles of miRNAs and long noncoding RNAs in the progression of diabetic retinopathy

Nuclear proteins and diabetic retinopathy: a review

Diabetic retinopathy (DR) is an eye disease that causes blindness and vision loss in diabetic. Risk factors for DR include high blood glucose levels and some environmental factors. The pathogenesis is based on inflammation caused by interferon and other nuclear proteins. This review article provides an overview of DR and discusses the role of nuclear proteins in the pathogenesis of the disease. Some core proteins such as MAPK, transcription co-factors, transcription co-activators, and others are part of this review. In addition, some current advanced treatment resulting from the role of nuclear proteins will be analyzes, including epigenetic modifications, the use of methylation, acetylation, and histone modifications. Stem cell technology and the use of nanobiotechnology are proposed as promising approaches for a more effective treatment of DR.

MiR-9-3 hypermethylation is associated with stages of diabetic retinopathy

Purpose

To investigate the potential relation between methylation of miR-9-3 and stages of diabetic retinopathy (DR). Additionally, we explored whether miR-9-3 methylation impacts the serum levels of Vascular Endothelial Growth Factor (VEGF).

Methods

A cross-sectional study was conducted with 170 participants with type 2 diabetes, including a control group (n = 64) and a diabetes retinopathy group (n = 106), which was further divided into NPDR (n = 58) and PDR (n = 48) subgroups. Epidemiological, clinical, anthropometric, biochemical ELISA assay were analysed. DNA extracted from leukocytes was used to profile miR-9-3 methylation using PCR-MSP.

Results

MiR-9-3 hypermethylated profile was higher in the DR group (p < 0.001) and PDR subgroup compared to DM2 control group (p < 0.001). The hypermethylated profile in the PDR subgroup was also higher compared to NPDR subgroup (p < 0.001). There was no difference between DM2 control and NPDR group (p = 0.234). Logistic regression showed that miR-9-3 hypermethylation increases the odds of presenting DR (OR: 2.826; p = 0.002) and PDR (OR: 5.472; p < 0.001). In addition, hypermethylation of miR-9-3 in the DR and NPDR subgroup was associated with higher serum VEGF-A levels (p = 0.012 and p = 0.025, respectively).

Conclusion

The methylation profile of the miR-9-3 promoter increases the risk of developing PDR. Higher levels of VEGF-A are associated with miR-9-3 hypermethylated profile in patients in the DR and NPDR stages.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01411-9.

Whole transcriptome sequencing reveals key genes and ceRNA regulatory networks associated with pimpled eggs in hens

Eggshell is one of the most important indicators of egg quality, and due to low shell strength, pimple eggs (PE) are more susceptible to breakage, thus causing huge economic losses to the egg industry. At the current time, the molecular mechanisms that regulate the formation of pimple eggs are poorly understood. In this study, uterine tissues of PE-laying hens (n = 8) and normal egg (NE) -laying hens (n = 8) were analyzed by whole transcriptome sequencing, and a total of 619 differentially expressed mRNAs (DE mRNAs), 122 differentially expressed lncRNAs (DE lncRNAs) and 21 differentially expressed miRNAs (DE miRNAs) were obtained. Based on the targeting relationship among DE mRNAs, DE lncRNAs and DE miRNAs, we constructed a competitive endogenous RNA (ceRNA) network including 12 DE miRNAs, 19 DE lncRNAs, and 128 DE mRNAs. Considering the large amount of information contained in the network, we constructed a smaller ceRNA network to better understand the complex mechanisms of pimple egg formation. The smaller ceRNA network network contains 7 DE lncRNAs (LOC107056551, LOC121109367, LOC121108909, LOC121108862, LOC112530033, LOC121113165, LOC107054145), 5 DE miRNAs (gga-miR-6568-3p, gga-miR-31-5p, gga-miR-18b-3p, gga-miR-1759-3p, gga-miR-12240-3p) and 7 DE mRNAs (CABP1, DNAJC5, HCN3, HPCA, IBSP, KCNT1, OTOP3), and these differentially expressed genes may play key regulatory roles in the formation of pimpled eggs in hens. This study provides the overall expression profiles of mRNAs, lncRNAs and miRNAs in the uterine tissues of hens, which provides a theoretical basis for further research on the molecular mechanisms of pimpled egg formation, and has potential applications in improving eggshell quality.

lncRNA MALAT1 promotes diabetic retinopathy by upregulating PDE6G via miR-378a-3p

Diabetic retinopathy (DR) is the main cause of adult insomnia, which causes certain social and economic pressure. This research was to investigate the role and regulatory mechanisms of MALAT1, miR-378a-3p and PDE6g in retinal microvascular endothelial cells (RMECs) under high glucose (HG). MALAT1, Mir-378a-3p and PDE6G expressions level were detected by qRT-PCR and Western blot. The proliferation, Bax and Bcl-2 protein expression of RMECs were detected by CCK-8 and western blot. The target relationships of MALAT1, miR-378a-3p and PDE6G were determined by bioinformatics analysis, dual-luciferase reporter gene, RIP and RNA pull-down assay. HG enhanced the expression of MALAT1 and PDE6G, and inhibited the expression of miR-378a-3p. Overexpression of MALAT1 promotes the proliferation of RMECs and inhibits apoptosis under HG condition. MALAT1 competitively adsorbed miR-378a-3p, which targeted PDE6G. Data reveal that MALAT1/miR-378a-3p/PDE6G signal axis restrain the apoptosis of RMECs under HG. This finding may help to delay the development of DR.

Non-coding RNAs and exosomal non-coding RNAs in diabetic retinopathy: A narrative review

Diabetic retinopathy (DR) is a devastating complication of diabetes, having extensive and resilient effects on those who suffer from it. As yet, the underlying cell mechanisms of this microvascular disorder are largely unclear. Recently, growing evidence suggests that epigenetic mechanisms can be responsible for gene deregulation leading to the alteration of key processes in the development and progression of DR, in addition to the widely recognized pathological mechanisms. It is noteworthy that seemingly unending epigenetic modifications, caused by a prolonged period of hyperglycemia, may be a prominent factor that leads to metabolic memory, and brings epigenetic entities such as non-coding RNA into the equation. Consequently, further investigation is necessary to truly understand this mechanism. Exosomes are responsible for carrying signals from cells close to the vasculature that are participating in abnormal signal transduction to faraway organs and cells by sailing through the bloodstream. These signs indicate metabolic disorders. With the aid of their encased structure, they can store diverse signaling molecules, which then can be dispersed into the blood, urine, and tears. Herein, we summarized various non-coding RNAs (ncRNAs) that are related to DR pathogenesis. Moreover, we highlighted the role of exosomal ncRNAs in this disease.

Bioinformatics and in vitro study reveal the roles of microRNA-346 in high glucose-induced human retinal pigment epithelial cell damage

AIM

To study microRNAs (miRNAs) and their potential effects in high glucose-induced human retinal pigment epithelial cell damage.

METHODS

We screened the GSE52233 miRNA expression dataset for differentially expressed miRNAs (DEMs). The target genes of the top 10 DEMs were predicted using miRWalk 2.0 database, followed by function enrichment and protein-protein interaction analysis. miRNA expression was determined in the human retinal pigment epithelial cell line ARPE-19 treated with high glucose (HG) by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Cell proliferation was determined using cell counting kit (CCK)-8 assay. Cell cycle, apoptosis, and reactive oxygen species (ROS) levels were determined by flow cytometry. The direct interaction between miRNA and targets was validated using dual-luciferase reporter assay.

RESULTS

Thirty-nine DEMs were screened, and we predicted 125 miRNA-mRNA pairs for the top 10 DEMs, including 119 target genes of seven DEMs such as miR-346, which was upregulated in diabetic retinopathy (DR). miR-346 target genes were substantially enriched in the regulation of intracellular transport and retinoic acid-inducible gene I (RIG-I)-like receptor signaling pathway. Expression of three upregulated and downregulated miRNAs were verified by qRT-PCR in HG-treated ARPE-19 cells. Expression of miR-346 was elevated in HG treated ARPE-19 cells in a dose-dependent manner. HG inhibited cell proliferation and induced apoptosis, which were partly reversed by transfecting an miR-346 inhibitor, which even decreased the ROS levels elevated due to HG. Argonaute 2 (AGO2) was a target of miR-346.

CONCLUSION

miR-346 is a key miRNA and plays an important role in HG-induced damage in human retinal pigment epithelial cells.

Inhibiting autophagy by miR-19a-3p/PTEN regulation protected retinal pigment epithelial cells from hyperglycemic damage

OBJECTIVE

The catabolic process of autophagy is arousing the attention of researchers studying diabetic retinopathy (DR), but the role and molecular mechanism of autophagy in DR are still unclear.

METHODS

An in vivo diabetic rat model and in vitro hyperglycemic-exposed retinal pigment epithelium (RPE) cell cultures were established to mimic early DR. Transmission electron microscopy and mRFP-GFP-LC3 adenovirus transfection were applied for autophagic flux analysis. MicroRNA (miR)-19a-3p, members of the phosphate and tensin homolog (PTEN)/Akt/mammalian target of rapamycin (mTOR) pathway, and the autophagy-related proteins light chain (LC)3II/I and p62 were detected. Annexin V, transwell, Cell Counting Kit-8, fluorescein isothiocyanate-dextran monolayer permeability assay, and transepithelial electrical resistance were performed to evaluate the effects of regulating autophagy on RPE cells under the DR condition.

RESULTS

Autophagy was aberrantly activated in DR as evidenced by autophagosome accumulation. Further mechanistic experiments revealed that DR induced PTEN expression, thus inhibiting Akt/mTOR phosphorylation and stimulating aberrant autophagy and apoptosis. Notably, these events could be reversed by miR-19a-3p directly targeting PTEN. Downregulation of autophagy by miR-19a-3p overexpression, PTEN knockdown, or 3-methyladenine (3-MA) treatment inhibited autophagosome formation and thus effectively ameliorated hyperglycemia-induced RPE cell apoptosis, increased migration, inhibited viability, and enhanced monolayer permeability under the DR condition.

CONCLUSIONS

Our findings suggest that upregulation of miR-19a-3p inhibits aberrant autophagy by directly targeting PTEN, thus protecting RPE cells against DR damage. miR-19a-3p may represent a novel therapeutic target for inducing protective autophagy in early DR.

lncRNA HOTAIR promotes ROS generation and NLRP3 inflammasome activation by inhibiting Nrf2 in diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a microvascular complication associated with damage to the retina due to inflammation induced by high glucose. Activation of the NLRP3 inflammasome plays a critical role in DR and its prevention is beneficial to patients. However, the regulation of long non-coding RNA (lncRNA) in NLRP3 inflammasome activation of DR is incompletely understood. So, this study aimed to uncover the functional and regulatory mechanism of the lncRNA HOTAIR in NLRP3 inflammasome activation in Dr.

METHODS

The vitreous humor was collected from the patients and detected the inflammatory and oxidative stress makers. Human retinal endothelial cells (HRECs) were cultured and stimulated in low D-glucose (5 mmol/L) or high D-glucose (20 mmol/L). Additionally, HRECs were knocked down HOTAIR with a si-RNA. Then, the NLRP3 inflammasome activation was analyzed by western blotting and pyroptosis cell imaging. The ROS was measured by specific probe. The activation of Nrf2 measured by Immunofluorescent staining. The interaction between HOTAIR and Nrf2 was evaluated by co-immunoprecipitation and RNA immunoprecipitation.

RESULTS

The expression of HOTAIR was significantly increased in the vitreous of patients with DR and in HRECs stimulated with high glucose. Furthermore, HOTAIR knockdown relieved NLRP3 inflammasome activation. More specifically, HOTAIR knockdown suppressed the expression of NLRP3, pro-caspase-1, and pro-IL-1β, as well as IL-1β maturation and pyroptosis. HOTAIR knockdown also interfered with the ROS generation induced by high glucose. Moreover, HOTAIR promoted the interaction between Nrf2 and Keap1 by binding and inactivating Nrf2.

CONCLUSION

The lncRNA HOTAIR promotes NLRP3 inflammasome activation and ROS generation by inhibiting Nrf2 in Dr.

Malignancy-related mir-210, mir-373 and let-7 levels are affected in iron deficiency anemia

Background

Hypoxia is the hallmark of iron deficiency anemia (IDA) and in hypoxic environment, significant changes are observed in malignancy-related microRNAs (miRNA). Our aim is to examine whether there is any difference in the levels of miR-210, miR-373 and let-7, which are directly related to malignancies in patients with IDA.

Methods

Thirty-five female patients with IDA between the ages of 18-65 and 10 healthy controls were included in the study. Patients who received oral iron therapy, who had inflammatory disease, and who were pregnant were excluded from the study. Student t Test was used for comparing variables with normal distribution in two independent groups, and Mann-Whitney U Test was used for variables without normal distribution. Comparison of categorical data was made using the chi-square test.

Results

The mean hemoglobin and ferritin level were 10,78±0,93 and 6.28±5,76 respectively. Plasma miR-210 expression were found as -7.27±2.23 and -6.15±0,88 in IDA and control group respectively (p = 0.022). Plasma miRNA-373 were -7.36±2,58 and -6,96±1,93 and let-7 expression were 2.14±2,15 and 3,57±2,21 in IDA and control group. (p = 0.65 and p = 0.20, respectively).

Conclusions

Plasma miR-210 expression was significantly up-regulated and miR-373 and let-7 expression was down-regulated, though insignificantly, in IDA group.

Regulation of Long Noncoding RNA NEAT1/miR-320a/HIF-1α Competitive Endogenous RNA Regulatory Network in Diabetic Retinopathy

Purpose

To determine the mechanism that long noncoding RNA NEAT1 (lncNEAT1)/miR-320a competitive endogenous RNA (ceRNA) network regulates hypoxia-inducible factor-1α (HIF-1α) in ARPE-19 cells and its potential role in diabetic retinopathy (DR).

Methods

ARPE-19 cells were cultured in a normal or high-glucose (HG) medium, and cell migration, invasion, and permeability were detected by scratch, transwell, and FITC-dextran staining assays. LncNEAT1, HIF-1α, ZO-1, occludin, N-cadherin, and vimentin levels were tested. The binding of lncNEAT1 to miR-320a was verified by dual-luciferase reporter assay, and the binding of miR-320a to HIF-1α by RIP assay. ARPE-19 cells were treated with lncNEAT1 or HIF-1α shRNA or miR-320a agomir to determine the activation of ANGPTL4/p-STAT3 pathway. The effect of lncNEAT1 in DR and its regulations on miR-320a and HIF-1α were determined in a rat model of DR.

Results

HG treatment promoted the migration, invasion, and permeability of ARPE-19 cells. After lncNEAT1 silencing, HIF-1α, N-cadherin, and vimentin levels were downregulated, ZO-1 and occludin levels were upregulated, and the migration, permeability, and invasion of HG-treated ARPE-19 cells were inhibited. However, HIF-1α overexpression increased N-cadherin and vimentin expression, reduced ZO-1 and occludin expression, and promoted the migration, permeability, and invasion of ARPE-19 cells. The binding of miR-320a with both lncNEAT1 and HIF-1α was predicted and confirmed. In a diabetic rat model, silencing lncNEAT1 inhibited HIF-1α/ANGPTL4/p-STAT3 pathway activation and alleviated retinopathy.

Conclusions

The lncNETA1/miR-320a/HIF-1α ceRNA network activates the ANGPTL4/p-STAT3 pathway and promotes HG-induced ARPE-19 cell invasion and migration.

MicroRNA 9 Is a Regulator of Endothelial to Mesenchymal Transition in Diabetic Retinopathy

Purpose

Diabetic retinopathy (DR) is a significant cause of blindness. Most research around DR focus on late-stage developments rather than early changes such as early endothelial dysfunction. Endothelial-to-mesenchymal transition (EndMT), an epigenetically regulated process whereby endothelial cells lose endothelial characteristics and adopt mesenchymal-like phenotypes, contributes to early endothelial changes in DR. The epigenetic regulator microRNA 9 (miR-9) is suppressed in the eyes during DR. MiR-9 plays a role in various diseases and regulates EndMT-related processes in other organs. We investigated the role miR-9 plays in glucose-induced EndMT in DR.

Methods

We examined the effects of glucose on miR-9 and EndMT using human retinal endothelial cells (HRECs). We then used HRECs and an endothelial-specific miR-9 transgenic mouse line to investigate the effect of miR-9 on glucose-induced EndMT. Finally, we used HRECs to probe the mechanisms through which miR-9 may regulate EndMT.

Results

We found that miR-9 inhibition was both necessary and sufficient for glucose-induced EndMT. Overexpression of miR-9 prevented glucose-induced EndMT, whereas suppressing miR-9 caused glucose-like EndMT changes. We also found that preventing EndMT with miR-9 overexpression improved retinal vascular leakage in DR. Finally, we showed that miR-9 regulates EndMT at an early stage by regulating EndMT-inducing signals such as proinflammatory and TGF-β pathways.

Conclusions

We have shown that miR-9 is an important regulator of EndMT in DR, potentially making it a good target for RNA-based therapy in early DR.

microRNA-96 targets the INS/AKT/GLUT4 signaling axis: Association with and effect on diabetic retinopathy

Background

miR-96-5p is a highly expressed microRNA in the retina of subjects with diabetes. The INS/AKT/GLUT4 signaling axis is the main cell signaling pathway of glucose uptake in cells. Here, we investigated the role of miR-96-5p in this signaling pathway.

Methods

Expression levels of miR-96-5p and its target genes were measured under high glucose conditions, in the retina of streptozotocin-induced diabetic mice, in the retina of AAV-2-eGFP-miR-96 or GFP intravitreal injected mice and in the retina of human donors with diabetic retinopathy (DR). MTT, wound healing, tube formation, Western blot, TUNEL, angiogenesis assays and hematoxylin-eosin staining of the retinal sections were performed.

Results

miR-96-5p expression was increased under high glucose conditions in mouse retinal pigment epithelial (mRPE) cells, in the retina of mice receiving AAV-2 carrying miR-96 and STZ-treated mice. Expression of the miR-96-5p target genes related to the INS/AKT/GLUT4 signaling pathway was reduced following miR-96-5p overexpression. mmu-miR-96-5p expression decreased cell proliferation and thicknesses of retinal layers. Cell migration, tube formation, vascular length, angiogenesis, and TUNEL-positive cells were increased.

Conclusions

In in vitro and in vivo studies and in human retinal tissues, miR-96-5p regulated the expression of the PIK3R1, PRKCE, AKT1, AKT2, and AKT3 genes in the INS/AKT axis and some genes involved in GLUT4 trafficking, such as Pak1, Snap23, RAB2a, and Ehd1. Because disruption of the INS/AKT/GLUT4 signaling axis causes advanced glycation end product accumulation and inflammatory responses, the inhibition of miR-96-5p expression could ameliorate DR.

Downregulation of plasma microRNA-29c-3p expression may be a new risk factor for diabetic retinopathy

BACKGROUND

Circulation miRNAs have emerged as new biomarkers for identifying and monitoring the microvascular complications of diabetes. The aim of this study is to evaluate the levels of five candidate miRNAs (miR-29c-3p, miR-18a, miR-31, miR-181 and miR-20a) in patients with diabetic retinopathy (DR) and their relationship with disease severity.

METHODS

The study included 31 diabetes patients without DR (NDR group), 68 patients with DR (DR group) and 30 healthy controls (HC group). Twenty-five of patients with DR were proliferative DR (PDR group) and 43 were non-proliferative DR (NPDR group) patients. Metabolic parameters and serum vascular endothelial growth factor (VEGF) levels of all participants were measured. Circulating miRNAs levels were determined by quantitative real-time PCR. Fundus examinations of all patients were performed by a single ophthalmologist.

RESULTS

VEGF levels were significantly higher in the NDR, and DR groups compared to HC group (P=0.011 and P=0.014, respectively). Plasma miR-29c-3p was downregulated in diabetic patients with retinopathy and without retinopathy. This downregulation was more prominent in diabetic patients without retinopathy compared to those with retinopathy (P=0.016). There was no significant difference in plasma levels of miR-18a, miR-20a, miR-18a and miR-31 between diabetic subjects with and without retinopathy (P>0.05). There was no correlation between DR severity and the levels of miRNAs (P>0.05). In multivariate logistic regression analysis, it was found that changes in plasma miR-29c-3p expression of diabetic patients increased DR risk independent of other risk factors.

CONCLUSIONS

Plasma miR-29c-3p expression is downregulated in diabetic patients with and without retinopathy, and changes in this miRNA are an independent risk factor for the development of DR.

Differences in junction-associated gene expression changes in three rat models of diabetic retinopathy with similar neurovascular phenotype

Diabetic retinopathy, also defined as microvascular complication of diabetes mellitus, affects the entire neurovascular unit with specific aberrations in every compartment. Neurodegeneration, glial activation and vasoregression are observed consistently in models of diabetic retinopathy. However, the order and the severity of these aberrations varies in different models, which is also true in patients. In this study, we analysed rat models of diabetic retinopathy with similar phenotypes to identify key differences in the pathogenesis. For this, we focussed on intercellular junction-associated gene expression, which are important for the communication and homeostasis within the neurovascular unit. Streptozotocin-injected diabetic Wistar rats, methylglyoxal supplemented Wistar rats and polycystin-2 transgenic (PKD) rats were analysed for neuroretinal function, vasoregression and retinal expression of junction-associated proteins. In all three models, neuroretinal impairment and vasoregression were observed, but gene expression profiling of junction-associated proteins demonstrated nearly no overlap between the three models. However, the differently expressed genes were from the main classes of claudins, connexins and integrins in all models. Changes in Rcor1 expression in diabetic rats and Egr1 expression in PKD rats confirmed the differences in upstream transcription factor level between the models. In PKD rats, a possible role for miRNA regulation was observed, indicated by an upregulation of miR-26b-5p, miR-122-5p and miR-300-3p, which was not observed in the other models. In silico allocation of connexins revealed not only differences in regulated subtypes, but also in affected retinal cell types, as well as connexin specific upstream regulators Sox7 and miR-92a-3p. In this study, we demonstrate that, despite their similar phenotype, models for diabetic retinopathy exhibit significant differences in their pathogenic pathways and primarily affected cell types. These results underline the importance for more sensitive diagnostic tools to identify pathogenic clusters in patients as the next step towards a desperately needed personalized therapy.

Ginsenoside Rg1 Inhibits High Glucose-Induced Proliferation, Migration, and Angiogenesis in Retinal Endothelial Cells by Regulating the lncRNA SNHG7/miR-2116-5p/SIRT3 Axis

Background

Diabetic retinopathy (DR), including retinal angiogenesis and endothelial cell proliferation and migration, is a serious complication in diabetic patients. It has been reported that ginsenoside Rg1 can prevent retinal damage. However, the mechanism by which Rg1 prevents retinal damage is unknown. Therefore, the aim of the present study was to investigate the mechanism by which Rg1 inhibits high glucose-induced complications through the regulation of the lncRNA SNHG7/miR-2116-5p/SIRT3 axis.

Methods

Under high glucose (HG) conditions, human retinal endothelial cells (HRECs) were cultured to simulate a DR environment, and Rg1 was added after 48 h. Negative control (NC), miR-2116-5p mimic, si-SNHG7, pc-DNA SIRT3, and miR-2116-5p inhibitor were transfected into HRECs, and CCK-8 assay was used to detect the cell viability. Angiogenesis and transwell assays were used to evaluate angiogenesis and cell migration, respectively. qRT-PCR and Western blot were used to detect the expression of related genes and proteins. Luciferase reporter assays and bioinformatics were used to analyze the target binding sites of miR-2116-5p to lncRNA SNHG7 and SIRT3.

Results

The proliferation, migration and angiogenesis of HRECs were induced by HG. As expected, HG upregulated miR-2116-5p and VEGF expression but downregulated lncRNA SNHG7 and SIRT3 expression. Importantly, Rg1 inhibited HG-induced HREC proliferation, migration, and angiogenesis by upregulating the lncRNA SNHG7, and miR-2116-5p had a target regulatory relationship with both lncRNA SNHG7 and SIRT3.

Conclusion

Rg1 inhibits HG-induced proliferation, migration, angiogenesis, and VEGF expression in retinal endothelial cells through the lncRNA SNG7/miR-2116-5p/SIRT3 axis. This finding provides theoretical evidence for the clinical application of Rg1 in DR.

Noncoding RNAs Are Promising Therapeutic Targets for Diabetic Retinopathy: An Updated Review (2017-2022)

Diabetic retinopathy (DR) is the most common complication of diabetes. It is also the main cause of blindness caused by multicellular damage involving retinal endothelial cells, ganglial cells, and pigment epithelial cells in adults worldwide. Currently available drugs for DR do not meet the clinical needs; thus, new therapeutic targets are warranted. Noncoding RNAs (ncRNAs), a new type of biomarkers, have attracted increased attention in recent years owing to their crucial role in the occurrence and development of DR. NcRNAs mainly include microRNAs, long noncoding RNAs, and circular RNAs, all of which regulate gene and protein expression, as well as multiple biological processes in DR. NcRNAs, can regulate the damage caused by various retinal cells; abnormal changes in the aqueous humor, exosomes, blood, tears, and the formation of new blood vessels. This study reviews the different sources of the three ncRNAs-microRNAs, long noncoding RNAs, and circular RNAs-involved in the pathogenesis of DR and the related drug development progress. Overall, this review improves our understanding of the role of ncRNAs in various retinal cells and offers therapeutic directions and targets for DR treatment.

miRNAs as Biomarkers in Diabetes: Moving towards Precision Medicine

Diabetes mellitus (DM) is a complex metabolic disease with many specifically related complications. Early diagnosis of this disease could prevent the progression to overt disease and its related complications. There are several limitations to using existing biomarkers, and between 24% and 62% of people with diabetes remain undiagnosed and untreated, suggesting a large gap in current diagnostic practices. Early detection of the percentage of insulin-producing cells preceding loss of function would allow for effective therapeutic interventions that could delay or slow down the onset of diabetes. MicroRNAs (miRNAs) could be used for early diagnosis, as well as for following the progression and the severity of the disease, due to the fact of their pancreatic specific expression and stability in various body fluids. Thus, many studies have focused on the identification and validation of such groups or "signatures of miRNAs" that may prove useful in diagnosing or treating patients. Here, we summarize the findings on miRNAs as biomarkers in diabetes and those associated with direct cellular reprogramming strategies, as well as the relevance of miRNAs that act as a bidirectional switch for cell therapy of damaged pancreatic tissue and the studies that have measured and tracked miRNAs as biomarkers in insulin resistance are addressed.

MicroRNA-150 (miR-150) and Diabetic Retinopathy: Is miR-150 Only a Biomarker or Does It Contribute to Disease Progression?

Diabetic retinopathy (DR) is a chronic disease associated with diabetes mellitus and is a leading cause of visual impairment among the working population in the US. Clinically, DR has been diagnosed and treated as a vascular complication, but it adversely impacts both neural retina and retinal vasculature. Degeneration of retinal neurons and microvasculature manifests in the diabetic retina and early stages of DR. Retinal photoreceptors undergo apoptosis shortly after the onset of diabetes, which contributes to the retinal dysfunction and microvascular complications leading to vision impairment. Chronic inflammation is a hallmark of diabetes and a contributor to cell apoptosis, and retinal photoreceptors are a major source of intraocular inflammation that contributes to vascular abnormalities in diabetes. As the levels of microRNAs (miRs) are changed in the plasma and vitreous of diabetic patients, miRs have been suggested as biomarkers to determine the progression of diabetic ocular diseases, including DR. However, few miRs have been thoroughly investigated as contributors to the pathogenesis of DR. Among these miRs, miR-150 is downregulated in diabetic patients and is an endogenous suppressor of inflammation, apoptosis, and pathological angiogenesis. In this review, how miR-150 and its downstream targets contribute to diabetes-associated retinal degeneration and pathological angiogenesis in DR are discussed. Currently, there is no effective treatment to stop or reverse diabetes-caused neural and vascular degeneration in the retina. Understanding the molecular mechanism of the pathogenesis of DR may shed light for the future development of more effective treatments for DR and other diabetes-associated ocular diseases.

The Role of miR-29 Family in TGF-β Driven Fibrosis in Glaucomatous Optic Neuropathy

Primary open angle glaucoma (POAG), a chronic optic neuropathy, remains the leading cause of irreversible blindness worldwide. It is driven in part by the pro-fibrotic cytokine transforming growth factor beta (TGF-β) and leads to extracellular matrix remodelling at the lamina cribrosa of the optic nerve head. Despite an array of medical and surgical treatments targeting the only known modifiable risk factor, raised intraocular pressure, many patients still progress and develop significant visual field loss and eventual blindness. The search for alternative treatment strategies targeting the underlying fibrotic transformation in the optic nerve head and trabecular meshwork in glaucoma is ongoing. MicroRNAs are small non-coding RNAs known to regulate post-transcriptional gene expression. Extensive research has been undertaken to uncover the complex role of miRNAs in gene expression and miRNA dysregulation in fibrotic disease. MiR-29 is a family of miRNAs which are strongly anti-fibrotic in their effects on the TGF-β signalling pathway and the regulation of extracellular matrix production and deposition. In this review, we discuss the anti-fibrotic effects of miR-29 and the role of miR-29 in ocular pathology and in the development of glaucomatous optic neuropathy. A better understanding of the role of miR-29 in POAG may aid in developing diagnostic and therapeutic strategies in glaucoma.

Differential expression analysis of mRNAs, lncRNAs, and miRNAs expression profiles and construction of ceRNA networks in PEDV infection

BACKGROUND

Porcine Epidemic Diarrhea Virus (PEDV) is a coronavirus that seriously affects the swine industry. MicroRNAs and long noncoding RNAs are two relevant non-coding RNAs (ncRNAs) class and play crucial roles in a variety of physiological processes. Increased evidence indicates a complex interaction between mRNA and ncRNA. However, our understanding of the function of ncRNA involved in host-PEDV interaction is limited.

RESULTS

A total of 1,197 mRNA transcripts, 539 lncRNA transcripts, and 208 miRNA transcripts were differentially regulated at 24 h and 48 h post-infection. Gene ontology (GO) and KEGG pathway enrichment analysis showed that DE mRNAs and DE lncRNAs were mainly involved in biosynthesis, innate immunity, and lipid metabolism. Moreover, we constructed a miRNA-mRNA-pathway network using bioinformatics, including 12 DE mRNAs, 120 DE miRNAs, and 11 pathways. Finally, the target genes of DE miRNAs were screened by bioinformatics, and we constructed immune-related lncRNA-miRNA-mRNA ceRNA networks. Then, the selected DE genes were validated by qRT-PCR, which were consistent with the results from RNA-Seq data.

CONCLUSIONS

This study provides the comprehensive analysis of the expression profiles of mRNAs, lncRNAs, and miRNAs during PEDV infection. We characterize the ceRNA networks which can provide new insights into the pathogenesis of PEDV.

The Protective Effects of Neurotrophins and MicroRNA in Diabetic Retinopathy, Nephropathy and Heart Failure via Regulating Endothelial Function

Diabetes mellitus is a common disease affecting more than 537 million adults worldwide. The microvascular complications that occur during the course of the disease are widespread and affect a variety of organ systems in the body. Diabetic retinopathy is one of the most common long-term complications, which include, amongst others, endothelial dysfunction, and thus, alterations in the blood-retinal barrier (BRB). This particularly restrictive physiological barrier is important for maintaining the neuroretina as a privileged site in the body by controlling the inflow and outflow of fluid, nutrients, metabolic end products, ions, and proteins. In addition, people with diabetic retinopathy (DR) have been shown to be at increased risk for systemic vascular complications, including subclinical and clinical stroke, coronary heart disease, heart failure, and nephropathy. DR is, therefore, considered an independent predictor of heart failure. In the present review, the effects of diabetes on the retina, heart, and kidneys are described. In addition, a putative common microRNA signature in diabetic retinopathy, nephropathy, and heart failure is discussed, which may be used in the future as a biomarker to better monitor disease progression. Finally, the use of miRNA, targeted neurotrophin delivery, and nanoparticles as novel therapeutic strategies is highlighted.

Long Non-coding RNAs: Pivotal Epigenetic Regulators in Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe complication of diabetes; however, its mechanism is not fully understood. Evidence has recently revealed that long non-coding RNAs (lncRNAs) are abnormally expressed in DR, and lncRNAs may function as pivotal regulators. LncRNAs are able to modulate gene expression at the epigenetic level by acting as scaffolds of histone modification complexes and sponges of binding with microRNAs (miRNAs). LncRNAs are believed to be important epigenetic regulators, which may become beneficial in the diagnosis and therapy of DR. However, the mechanisms of lncRNAs in DR are still unclear. In this review, we summarize the possible functions and mechanisms of lncRNAs in epigenetic regulation to target genes in the progression of DR.

The Correlation Between MicroRNAs and Diabetic Retinopathy

Micro ribonucleic acids (miRNAs), as a category of post-transcriptional gene inhibitors, have a wide range of biological functions, are involved in many pathological processes, and are attractive therapeutic targets. Considerable evidence in ophthalmology indicates that miRNAs play an important role in diabetic retinopathy (DR), especially in inflammation, oxidative stress, and neurodegeneration. Targeting specific miRNAs for the treatment of DR has attracted much attention. This is a review focusing on the pathophysiological roles of miRNAs in DR, diabetic macular edema, and proliferative DR complex multifactorial retinal diseases, with particular emphasis on how miRNAs regulate complex molecular pathways and underlying pathomechanisms. Moreover, the future development potential and application limitations of therapy that targets specific miRNAs for DR are discussed.

Circ_0001897 regulates high glucose-induced angiogenesis and inflammation in retinal microvascular endothelial cells through miR-29c-3p/transforming growth factor beta 2 axis

Diabetic retinopathy (DR) has become the leading cause of blindness among adults at working age. Previous studies have implicated circ_0001897 in the development of DR. In this study, we investigated the functional roles and mechanisms of circ_0001897 in high glucose-induced angiogenesis and inflammation. Peripheral blood samples from DR patients and healthy controls were collected to examine circ_0001897 expression, which demonstrated a significant upregulation of circ_0001897 in DR patients. To investigate the functional role and mechanisms of circ_0001897, human retinal microvascular endothelial cells (HRECs) were treated with high glucose (HG) to establish an in vitro DR model of endothelial cells. HG treatment induced the upregulation of circ_0001897 in HRECs, and enhanced cell proliferation, inflammatory responses, as well as in vitro angiogenesis. Circ_0001897 knockdown significantly attenuated the cell proliferation, inflammatory responses, and angiogenesis induced by HG treatment. Mechanistically, circ_0001897 sponged and inhibited the activity of mir-29c-3p, which in turn regulates the downstream target transforming growth factor beta 2 (TGFB2). The effects of circ_0001897 knockdown could be rescued by mir-29c-3p inhibitor or TGFB2 overexpression. Collectively, our data demonstrated the novel role of circ_0001897/mir-29c-3p/TGFB2 axis in regulating HG-induced inflammation and angiogenesis of HRECs. These findings suggest that targeting circ_0001897 could serve as an intervention strategy to ameliorate DR.

Diagnostic circulating biomarkers to detect vision-threatening diabetic retinopathy: Potential screening tool of the future?

With the increasing prevalence of diabetes in developing and developed countries, the socio-economic burden of diabetic retinopathy (DR), the leading complication of diabetes, is growing. Diabetic retinopathy (DR) is currently one of the leading causes of blindness in working-age adults worldwide. Robust methodologies exist to detect and monitor DR; however, these rely on specialist imaging techniques and qualified practitioners. This makes detecting and monitoring DR expensive and time-consuming, which is particularly problematic in developing countries where many patients will be remote and have little contact with specialist medical centres. Diabetic retinopathy (DR) is largely asymptomatic until late in the pathology. Therefore, early identification and stratification of vision-threatening DR (VTDR) is highly desirable and will ameliorate the global impact of this disease. A simple, reliable and more cost-effective test would greatly assist in decreasing the burden of DR around the world. Here, we evaluate and review data on circulating protein biomarkers, which have been verified in the context of DR. We also discuss the challenges and developments necessary to translate these promising data into clinically useful assays, to detect VTDR, and their potential integration into simple point-of-care testing devices.

Potential value of lncRNAs as a biomarker for proliferative diabetic retinopathy

OBJECTIVES

To investigate the differences in lncRNAs expression in whole blood between diabetic retinopathy (DR) patients and healthy subjects, and to evaluate the potential value of lncRNAs as a diagnostic biomarker for proliferative diabetic retinopathy (PDR).

METHODS

A series of 34 PDR patients, 34 patients with non-proliferative DR (NPDR) and 34 healthy participants were enroled. Differentially expressed lncRNAs were demonstrated using high-throughput sequencing and validated using qRT-PCR. Gene Ontology (GO) was performed to explore the possible biological function of the differentially expressed lncRNAs. lncRNA/mRNA coexpression network was built to determine the targets of differentially expressed lncRNAs. Receiver operating characteristic (ROC) analysis was utilized to evaluate the diagnostic value of lncRNAs for PDR.

RESULTS

We identified 175 and 179 differentially expressed lncRNAs in PDR patients compared with control samples and NPDR patients, respectively. GO analysis showed that the various metabolic processes were possibly influenced by these dysregulated lncRNAs. Using the differently expressed lncRNAs data, we further identified 82 overlapping lncRNAs in PDR patients with NPDR and control subjects. Part of these overlapping lncRNAs was significantly correlated with nuclear factor kappa B (NF-κB) and Wnt signal pathways. ROC curves were constructed for two upregulated lncRNAs and the ROC analysis indicated that both of them had potential diagnostic value and could distinguish PDR from control subjects and NPDR patients.

CONCLUSIONS

LncRNAs expression was altered in PDR patients compared with NPDR and control subjects. Moreover, it provides a resource that lncRNAs might be novel diagnostic and prognostic biomarker for PDR.

Mi-RNA-93 and Mi-RNA-152 in the Diagnosis of Type 2 Diabetes and Diabetic Retinopathy

Background and Aim: Diabetes mellitus (DM) is a chronic disorder with diabetic retinopathy (DR) as one of its main microvascular outcomes, being a prime cause of vision loss. Dysregulation of microRNAs (miRNAs) has been associated with some diabetic microvascular complications such as diabetic retinopathy. This hypothesised changes in the serum of miR-93 and miR-152 in diabetes and diabetic retinopathy.

Methods: The study cohort consisted of 80 healthy volunteers, 80 type 2 diabetic patients, and 80 diabetic retinopathy patients, of whom 40 had proliferative (PDR) and 40 non-proliferative retinopathy (NPDR). Serum fasting and 2-hour postprandial glucose (2hPP), glycated haemoglobin (HbA1c), fasting insulin, and HOMA-IR were evaluated by routine methods, miR-93 and miR-152 expression by quantitative real-time PCR.

Results: FBG, 2hPP, fasting insulin, HOMA-IR, and miR-152 showed an increasing trend across groups while miR-93 showed a decreasing trend (all p < 0.001). Binary logistic regression analysis for prediction of DR found that the most significant were miR-152 (OR 1.37, 95% CI: 1.18–1.58, <0.001), BMI (1.13, [1.07–1.31], p = 0.004), duration of disease (1.29 [1.04–1.6] p = 0.018), and miR-152 (0.01, [0.0–0.47] p = 0.019). The most significant predictors of PDR were miR-152 (OR = 1.47, 95% CI: 1.12–1.92, p = 0.005), HOMA-IR (2.66 [1.30–5.45] p = 0.007), and miR-93 (0.25 [0.07–0.86] p = 0.028).

Conclusion: MiR-93 and miR-152 can differentiate patients with diabetes and those with DR. Both miRNAs might be potential biomarkers for diabetes and diabetic retinopathy, and specifically for proliferative diabetic retinopathy.

Effect of Shuangdan Mingmu Capsule on Diabetic Retinopathy in Rats via Regulation of miRNAs

PURPOSE

To evaluate the effects of Shuangdan Mingmu (SDMM) capsule on diabetic retinopathy in rats by regulating miRNAs.

MATERIALS AND METHODS

Streptozotocin (STZ) (50 mg/kg) was successfully used to induce diabetes in male Sprague-Dawley rats, which were randomly assigned to a group taking SDMM capsules ("diabetic+SDMM") or a control group ("diabetic"), and the normal group (n=10/group). The diabetic+SDMM capsule group received 1.89g/kg/d of SDMM capsule by gavage, whereas the other groups received the same amount of distilled water. After 12-weeks of gavage, the retina was removed from all rats for histopathological analysis, and miRNA sequencing experiments were carried out to identify the differential expression of miRNAs. These results were then confirmed by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

SDMM capsules improved retinal morphology, restored the number of cells in the ganglion cell layer (p<0.0001) and reduced apoptosis in all retinal layers (p values in the outer nuclear layers, inner nuclear layers and ganglion cell layers 0.0001, 0.0147, 0.0034, respectively). In addition, miRNA expression was changed in rats taking SDMM capsules. Compared with the diabetic group, six miRNAs were up-regulated and four miRNAs were down-regulated in the diabetic+SDMM capsule group. The qRT-PCR validation results showed that the expression levels of miR-450b-5p, miR-1249 and miR-155-5p were consistent with the trend of miRNA sequencing results, and were all up-regulated after SDMM capsule treatment. Target gene prediction and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed miRNAs showed that these pathways were mainly concentrated in the focal adhesions and PI3K/Akt, MAPK, and neural factor signaling pathways.

CONCLUSION

SDMM capsules may prevent and treat diabetic retinopathy by regulating the expression of miR-450b-5p, miR-1249 and miR-155-5p.

Inhibitory effect of miR‑182‑5p on retinal neovascularization by targeting angiogenin and BDNF

Retinal neovascularization (RNV) is a type of serious vision-threating disease, commonly induced by hypoxia of ischemic retinopathy, which happens in various ocular diseases including diabetic retinopathy and retinopathy of prematurity. In clinical work, anti-VEGF therapy is the preferred strategy for treating RNV. However, not all cases are sensitive to anti-VEGF injection. It is urgent and necessary to develop novel targets for inhibiting neovascularization in ocular diseases. Angiogenin (ANG) and brain-derived neurotrophic factor (BDNF) are implicated in angiogenesis, although their regulation and effects in RNV remain to be elucidated. microRNA (miRNA) is a type of small non-coding RNA, which can modulate targets by degrading transcripts or inhibiting protein translation. In the present study, miRNA-mediated modulation of ANG and BDNF was explored in an oxygen-induced retinopathy mouse model and human retinal microvascular endothelial cells (HRECs) under hypoxia. The results showed that downregulation of miR-182-5p and upregulation of ANG and BDNF were found in vivo and in vitro. Overexpression of miR-182-5p suppressed the expression of ANG and BDNF significantly in HRECs under hypoxia. In addition, knockdown of ANG and BDNF by miR-182-5p transfection significantly improved hypoxia-induced HRECs dysfunctions, including enhancing cell viability, reducing cell migration and improved tube integrity. In conclusion, miRNA-dependent regulation on ANG and BDNF indicates a critical role in hypoxia-induced retinal microvascular response. miR-182-5p-based therapy can influence the expression of ANG and BDNF, which demonstrates the potential for treating RNV diseases.

miRNA Levels as a Biomarker for Anti-VEGF Response in Patients with Diabetic Macular Edema

BACKGROUND

The aim of this study was to investigate whether miRNA levels in the circulation could serve as a predictive biomarker for responsiveness to anti-vascular endothelial growth factor (VEGF) therapy in patients with diabetic macular edema.

METHODS

Whole blood samples were collected at baseline from 135 patients who were included in the BRDME study, a randomized controlled comparative trial of monthly bevacizumab or ranibizumab treatment for 6 months in patients with diabetic macular edema (Trialregister.nl, NTR3247). Best corrected visual acuity letter score (BCVA) and retinal central area thickness (CAT) were measured monthly during the 6-month follow-up. Levels of selected miRNAs were quantified.

RESULTS

Following linear regression analysis, the levels of four miRNAs were negatively associated with baseline CAT. Multivariable regression analysis confirmed this association for miR-181a. No associations with changes in CAT after 3 or 6 months of anti-VEGF treatment were found. In addition, no associations with miRNA levels with baseline BCVA or change in BCVA after 3 or 6 months of anti-VEGF treatment were found.

CONCLUSIONS

Circulating miR-181a levels were negatively associated with CAT at baseline. However, no associations between miRNA levels and the response to anti-VEGF therapy were found.

MicroRNA-139-5p Alleviates High Glucose-Triggered Human Retinal Pigment Epithelial Cell Injury by Targeting LIM-Only Factor 4

Diabetic retinopathy (DR) is a type of diabetes complication, which can result in loss of vision in adults worldwide. Increasing evidence has revealed that microRNAs (miRs) can regulate DR progression. Thus, the present study was aimed at assessing the possible mechanism of miR-139-5p in high glucose- (HG-) incubated retinal pigment epithelial (ARPE-19) cells. The present results demonstrated that miR-139-5p expression was notably reduced in the serum samples of patients with DR, as well as in ARPE-19 cells treated with HG in a time-dependent manner. Moreover, miR-139-5p was markedly overexpressed by transfection of miR-139-5p mimics into ARPE-19 cells. Overexpression of miR-139-5p markedly induced cell viability and repressed HG-triggered apoptosis. Furthermore, overexpression of miR-139-5p relived HG-enhanced oxidative stress injury. It was found that HG induced malondialdehyde levels but decreased superoxide dismutase and glutathione peroxidase activities in ARPE-19 cells. In addition, overexpression of miR-139-5p could markedly decrease intracellular stress. The results demonstrated that overexpression of miR-139-5p effectively repressed HG-activated inflammation, as indicated by the upregulation of inflammation cytokines, including TNF-α, IL-6, and Cox-2, in ARPE-19 cells. Subsequently, it was identified that LIM-only factor 4 (LMO4) could act as a downstream target for miR-139-5p. LMO4 expression was significantly increased in patients with DR and HG-treated ARPE-19 cells. Mechanistically, knockdown of LMO4 reversed the biological role of miR-139-5p in proliferation, apoptosis, oxidative stress, and release of inflammation factors in vitro. Collectively, these results suggested that miR-139-5p significantly decreased ARPE-19 cell injury caused by HG by inducing proliferation and suppressing cell apoptosis, oxidant stress, and inflammation by modulating LMO4.

Knockdown of Long Non-coding RNA TUG1 Suppresses Migration and Tube Formation in High Glucose-Stimulated Human Retinal Microvascular Endothelial Cells by Sponging miRNA-145

Diabetic retinopathy (DR) is a serious complication of diabetes mellitus. The purpose of this study was to investigate the potential functional role of long non-coding RNA TUG1 in high glucose (HG)-stimulated human retinal microvascular endothelial cells (hRMECs). The results demonstrated that following 72 h of HG stimulation, enhanced proliferation, migration, and tube formation process were observed in hRMECs. Moreover, HG treatment markedly increased TUG1 expression in hRMECs, and knockdown of TUG1 notably restrained the aberrant phenotypes of hRMECs induced by HG. Mechanistically, TUG1 may serve as a competing endogenous RNA (ceRNA) for miR-145, thereby blocking the repression on VEGF-A in hRMECs. Rescue experiments further indicated that inhibition of miR-145 abolished the beneficial role of TUG1 knockdown in HG-treated hRMECs. Our data suggested that knockdown of TUG1 protects hRMECs against HG stimulation partly by regulating miR-145/VEGF-A axis.

MicroRNA and diabetic retinopathy-biomarkers and novel therapeutics

Diabetic retinopathy (DR) accounts for ~80% of legal blindness in persons aged 20-74 years and is associated with enormous social and health burdens. Current therapies are invasive, non-curative, and in-effective in 15-25% of DR patients. This review outlines the potential utility of microRNAs (miRNAs) as biomarkers and potential therapy for diabetic retinopathy. miRNAs are small noncoding forms of RNA that may play a role in the pathogenesis of DR by altering the level of expression of genes via single nucleotide polymorphism and regulatory loops. A majority of miRNAs are intracellular and specific intracellular microRNAs have been associated with cellular changes associated with DR. Some microRNAs are extracellular and called circulatory microRNAs. Circulatory miRNAs have been found to be differentially expressed in serum and bodily fluid in patients with diabetes mellitus (DM) with and without retinopathy. Some miRNAs have been associated with the severity of DR, and future studies may reveal whether circulatory miRNAs could serve as novel reliable biomarkers to detect or predict retinopathy progression. Therapeutic strategies can be developed utilizing the natural miRNA/long noncoding RNA (lncRNA) regulatory loops. miRNAs and lncRNAs are two major families of the non-protein-coding transcripts. They are regulatory molecules for fundamental cellular processes via a variety of mechanisms, and their expression and function are tightly regulated. The recent evidence indicates a cross-talk between miRNAs and lncRNAs. Therefore, dysregulation of miRNAs and lncRNAs is critical to human disease pathogenesis, such as diabetic retinopathy. miRNAs are long-distance communicators and reprogramming agents, and they embody an entirely novel paradigm in cellular and tissue signaling and interaction. By targeting specific miRNAs, whole pathways implicated in the pathogenesis of DR may potentially be altered. Understanding the endogenous roles of miRNAs in the pathogenesis of diabetic retinopathy could lead to novel diagnostic and therapeutic approaches to managing this frequently blinding retinal condition.

Long Non-Coding RNAs Gene Variants as Molecular Markers for Diabetic Retinopathy Risk and Response to Anti-VEGF Therapy

Background

Long non-coding RNAs (lncRNAs) play essential roles in molecular diagnosis and therapeutic response in several diseases.

Purpose

For the first time, we aimed to evaluate the association of four lncRNAs TUG1 (rs7284767G/A), MIAT (rs1061540T/C), MALAT1 (rs3200401C/T), and SENCR (rs12420823C/T) variants with susceptibility to diabetic retinopathy (DR), disease severity, and early therapeutic response to intravitreous anti-vascular endothelial growth factor aflibercept therapy.

Patients and Methods

This case-control study enrolled 126 adult patients with type 2 diabetes. TaqMan assays using Real-Time PCR were run for genotyping. Multivariable regression analyses were applied to assess the role of each polymorphism after the adjustment of covariates.

Results

Carriers of TUG1 A/G and MIAT T/C and C/C genotypes were more likely to develop DR [OR=3.15 (95% CI=1.15–8.64), and OR=4.31 (95% CI=1.78–10.47)], while MALAT1 T/C conferred protection (OR=0.40, 95% CI=0.16–0.99). For TUG1, MALAT1, MIAT, and SENCR genotype combinations, GTCT and GCCC had a higher disease risk (P=0.012). For disease severity, MIAT T/T homozygosity was associated with higher DR grade [33.3% (T/T) vs 10% (C/C) and 4.2% (C/T) carriers, P=0.012]. Otherwise, patients with the SENCR T variant exhibited better pre-treatment best-corrected visual acuity level (p=0.021). Following aflibercept administration, carrying the TUG1 A or MIAT T/C was associated with a poor therapeutic response (OR=5.02, 95% CI=1.60–15.76, and OR=10.23, 95% CI=1.51–69.15, respectively).

Conclusion

The lncRNAs TUG1 (rs7284767G/A) and MIAT (rs1061540T/C) were associated with increased DR susceptibility and poor response to aflibercept treatment, while MALAT1 (rs3200401C/T) conferred protection to DR. These genetic determinants could be useful in DR risk stratification and pharmacogenetics after validation in large-scale studies.

LINC01133 promotes the progression of cervical cancer via regulating miR-30a-5p/FOXD1

BACKGROUND

The prognosis of patients with recurrent or metastatic cervical cancer (CC) remains poor, and its incidence is especially high in developing countries. Multiple long noncoding RNAs are recently identified as crucial oncogenic factors or tumor suppressors. In this study, we explored the function and mechanism of LINC01133 during the progression of CC.

METHODS

Expression levels of LINC01133 and miR-30a-5p in 50 CC tissue samples were measured using quantitative real-time polymerase chain reaction. Immunohistochemistry and Western blot analysis were used to detect the expression of oncogene forkhead box D1 (FOXD1). The association between pathological indices and the expression level of LINC01133 was also analyzed. Human CC cell lines HeLa and SiHa were used as cell models. CCK-8 and bromodeoxyuridine assays were used to assess the effect of LINC01133 on CC cell line proliferation. Flow cytometry was used to study the effect of LINC01133 on CC apoptosis. Transwell assay was conducted to detect the effect of LINC01133 on migration and invasion. Furthermore, luciferase reporter assay was used to confirm the targeting relationship between miR-30a-5p to LINC01133.

RESULTS

We observed that LINC01133 expression in CC clinical samples was significantly increased, with high expression associated with higher T stage and negative HPV infection of the patients. Its overexpression remarkably accelerated proliferation and metastasis of CC cells, with reduced apoptosis. LINC01133 knockdown suppressed the malignant phenotypes of CC cells. Overexpression of LINC01133 significantly reduced the expression of miR-30a-5p by sponging it and enhanced the expression of FOXD1.

CONCLUSIONS

We report the overexpression of LINC01133 in CC sample and cell lines, which correlated with unfavorable pathological indices. LINC01133 was a sponge of tumor suppressor miR-30a-5p, and it enhanced the expression of FOXD1 indirectly and functioned as an oncogenic lncRNA in CC.

Involvement of miR-126 rs4636297 and miR-146a rs2910164 polymorphisms in the susceptibility for diabetic retinopathy: a case-control study in a type 1 diabetes population

BACKGROUND AND PURPOSE

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression. MiRNA-126 and miRNA-146a have been described as having abnormal expressions in diabetic retinopathy (DR) patients. Polymorphisms in genes codifying miRNAs (miRSNPs) may alter the expression of the corresponding miRNA and, thus, interfere with susceptibility to DR. Therefore, miRSNPs in miR-126 and miR-146a genes could be associated with DR susceptibility. The purpose of this study was to investigate the association between miR-126 rs4636297 (G/A) and miR-146a rs2910164 (G/C) miRSNPs and DR.

METHODS

This case-control study included 195 type 1 diabetes mellitus (T1DM) patients with DR (cases) and 215 patients without DR and with ≥10 years of T1DM (controls). MiRSNPs were genotyped by real-time PCR.

RESULTS

Genotype distributions of two analysed miRSNPs were in Hardy-Weinberg equilibrium in controls (p > 0.050). Frequencies of the miR-126 rs4636297 miRSNP were not significantly different between case and control groups (p = 0.169). However, after adjustment for age, glycated haemoglobin, triglycerides, estimated glomerular filtration rate and ethnicity, the A allele of this miRSNP was associated with protection for DR under additive [OR: 0.444 (95% CI: 0.211-0.936), p = 0.033] and dominant [OR: 0.512 (95% CI: 0.303-0.865), p = 0.012] inheritance models. Genotype and allele frequencies of miR-146a rs2910164 miRSNP did not differ between groups (p = 0.368 and p = 0.957), and this polymorphism was not associated with DR when assuming different inheritance models.

CONCLUSION

Our results suggest an association between the A allele of miR-126 rs4636297 miRSNP and protection for DR in a Southern Brazilian population.

DNMT1-mediated lncRNA MEG3 methylation accelerates endothelial-mesenchymal transition in diabetic retinopathy through the PI3K/Akt/mTOR signaling pathway

Diabetic retinopathy (DR) is one of the serious complications that occurs in diabetic patients that frequently causes blindness. Long noncoding RNAs (lncRNAs) have been associated with DR pathology. This study aimed to determine the underlying mechanism of lncRNA maternally expressed gene 3 (MEG3) in association with DNA methyltransferase 1 (DNMT1) in the endothelial-mesenchymal transition (endMT) that occurs in DR. A rat model of DR was induced by streptozotocin (STZ) injection, and a high-glucose (HG)-induced cell model was established by exposing microvascular endothelial cells obtained from retina of rats to HG. Subsequently, MEG3 was overexpressed in rat and cell models to characterize its impact on endMT in DR and the involvement of the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway. Furthermore, the methylation level of MEG3 promoter region was determined with the application of methylation-specific polymerase chain reaction, followed by chromatin immunoprecipitation assay for methyltransferase enrichment. Finally, we examined the regulation of DNMT1 on MEG3 methylation and endMT in the HG-induced cell model. The results obtained revealed downregulated MEG3 expression in DR rat and cell models. Overexpressed MEG3 was shown to suppress endMT in DR rat and cell models through the inhibition of the PI3K/Akt/mTOR signaling pathway. Notably, DNMT1 could promote MEG3 promoter methylation to inhibit MEG3 expression by recruiting methyltransferase, which activated the PI3K/Akt/mTOR signaling pathway to accelerate endMT in DR. These findings further highlighted the inhibitory effect of MEG3 on endMT in DR, thus presenting a novel therapeutic target candidate for DR treatment.

MSC-derived exosomal lncRNA SNHG7 suppresses endothelial-mesenchymal transition and tube formation in diabetic retinopathy via miR-34a-5p/XBP1 axis

AIMS

Diabetic retinopathy (DR) is the most common complication of type 2 diabetes mellitus, which could result in visual impairment. Accumulating studies have shown the implication of long non-coding RNAs (lncRNAs) in the pathogenesis of DR. Our aims are to investigate whether lncRNA SNHG7 plays a role during DR pathogenesis.

MAIN METHODS

Human retinal microvascular endothelial cells (HRMECs) were treated with high glucose (HG) to build cell model. Relative expression of RNAs were examined using qPCR, and western blot or immunofluorescence analysis was adopted to detect the protein expression. Cell viability, migration and angiogenic capacity of HRMECs were estimated through CCK-8, transwell and tube formation experiments, respectively. Dual-luciferase reporter and RNA pull down assays were employed to verify the interplay between miR-34a-5p and SNHG7 or XBP1. Mesenchymal stem cells (MSCs) were identified by examining typical surface makers using flow cytometry and the differentiation abilities via Alizarin red, Oil red O and Alcian blue staining. MSC-derived exosomes were verified by transmission electron microscopy and western blot.

KEY FINDINGS

LncRNA SNHG7 sponged to and negatively regulated miR-34a-5p. SNHG7 overexpression repressed HG induced endothelial-mesenchymal transition (EndMT) and tube formation of HRMECs, while miR-34a-5p overexpression could reverse this effect. miR-34a-5p targeted and negative regulated XBP1. Knockdown of miR-34a-5p repressed HG induced EndMT and tube formation, which were partially blocked by XBP1 inhibition. MSC-derived exosomes could transfer SNHG7 to HRMECs and modulated EndMT and tube formation.

SIGNIFICANCE

The MSC-derived exosomal lncRNA SNHG7 suppresses EndMT and tube formation in HRMECs via miR-34a-5p/XBP1 axis.

Upregulation of long non-coding RNA SNHG16 promotes diabetes-related RMEC dysfunction via activating NF-κB and PI3K/AKT pathways

Diabetic retinopathy (DR) is a severe diabetes-induced eye disease, in which its pathological phenomena basically include abnormal proliferation, migration, and angiogenesis of microvascular endothelial cells in the retina. Long non-coding RNAs (lncRNAs) have been proven to be important regulators in various biological processes, but their participation in DR remains largely undiscovered. In the present study, we aimed to unveil the role of lncRNA small nucleolar RNA host gene 16 (SNHG16) in regulating the functions of human retinal microvascular endothelial cells (hRMECs) under a high-glucose (HG) condition. We found that SNHG16 expression was significantly upregulated in hRMECs treated with HG. Functionally, SNHG16 could facilitate hRMEC proliferation, migration, and angiogenesis. Moreover, SNHG16 was associated with nuclear factor κB (NF-κB) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. Mechanistically, SNHG16 could promote hRMEC dysfunction by sequestering microRNA (miR)-146a-5p and miR-7-5p to act as a competing endogenous RNA (ceRNA) with interleukin-1 receptor-associated kinase 1 (IRAK1) and insulin receptor substrate 1 (IRS1). In conclusion, our results illustrated the potential role of SNHG16 in facilitating hRMEC dysfunction under HG treatment, providing a novel approach for DR therapy.

LncRNA APCDD1L-AS1 induces icotinib resistance by inhibition of EGFR autophagic degradation via the miR-1322/miR-1972/miR-324-3p-SIRT5 axis in lung adenocarcinoma

BACKGROUND

Epidermal growth factor receptor-tyrosinase kinase inhibitor (EGFR-TKI) resistance is the major obstacle in the treatment of lung adenocarcinoma (LUAD) patients harboring EGFR-sensitive mutations. However, the long non-coding RNAs (lncRNAs) related to EGFR-TKIs resistance and their functional mechanisms are still largely unknown. This study aimed to investigate the role and regulatory mechanism of lncRNA APCDD1L-AS1 in icotinib resistance of lung cancer.

METHODS

Molecular approaches including qRT-PCR, MTT assay, colony formation, RNA interference and cell transfection, RNA immunoprecipitation (RIP), dual luciferase reporter assay, RNA fluorescence in situ hybridization, TUNEL assay, flow cytometry, immunoblotting, xenograft model and transcriptome sequencing were used to investigate the mechanism of APCDD1L-AS1 in icotinib resistance.

RESULTS

A novel lncRNA, APCDD1L-AS1 was identified as the most significantly upregulated lncRNA in icotinib-resistant LUAD cells by the transcriptome sequencing and differential lncRNA expression analysis. We found that APCDD1L-AS1 not only promoted icotinib resistance, but also upregulated the protein expression level of EGFR. Mechanistically, APCDD1L-AS1 promoted icotinib resistance and EGFR upregulation by sponging with miR-1322/miR-1972/miR-324-3p to remove the transcription inhibition of SIRT5. Furthermore, SIRT5 elevated EGFR expression and activation by inhibiting the autophagic degradation of EGFR, finally promoting icotinib resistance. Consistently, the autophagy initiator rapamycin could decrease EGFR levels and increase the sensitivity of icotinib-resistant LUAD cells to icotinib.

CONCLUSION

APCDD1L-AS1 could promote icotinib resistance by inhibiting autophagic degradation of EGFR via the miR-1322/miR-1972/miR-324-3p-SIRT5 axis. The combination of autophagy initiator and EGFR-TKIs might serve as a potential new strategy for overcoming EGFR-TKIs resistance in LUAD patients.

RNA therapeutics for retinal diseases

INTRODUCTION

In the retina, noncoding RNA (ncRNA) plays an integral role in regulating apoptosis, inflammatory responses, visual perception, and photo-transduction, with altered levels reported in diseased states.

AREAS COVERED

MicroRNA (miRNA), a class of ncRNA, regulates post-transcription gene expression through the binding of complementary sites of target messenger RNA (mRNA) with resulting translational repression. Small-interfering RNA (siRNA) is a double-stranded RNA (dsRNA) that regulates gene expression, leading to selective silencing of genes through a process called RNA interference (RNAi). Another form of RNAi involves short hairpin RNA (shRNA). In age-related macular degeneration (AMD) and diabetic retinopathy (DR), miRNA has been implicated in the regulation of angiogenesis, oxidative stress, immune response, and inflammation.

EXPERT OPINION

Many RNA-based therapies in development are conveniently administered intravitreally, with the potential for pan-retinal effect. The majority of these RNA therapeutics are synthetic ncRNA's and hold promise for the treatment of AMD, DR, and inherited retinal diseases (IRDs). These RNA-based therapies include siRNA therapy with its high specificity, shRNA to 'knock down' autosomal dominant toxic gain of function-mutated genes, antisense oligonucleotides (ASOs), which can restore splicing defects, and translational read-through inducing drugs (TRIDs) to increase expression of full-length protein from genes with premature stop codons.

MicroRNA-148a-3p alleviates high glucose-induced diabetic retinopathy by targeting TGFB2 and FGF2

AIMS

Diabetic retinopathy (DR), a common complication of type 1 or type 2 diabetes mellitus, has become the leading cause of blindness among adults in working age. The dysregulation of microRNA has been reported to be strongly related to the initiation or progression of DR. However, neither the biological role nor the molecular mechanism of miR-148a-3p has been researched in DR. This study is designed to investigate the function and mechanism of miR-148a-3p in DR.

METHODS

The bioinformatics analysis (Targetscan: https://www.targetscan.org/vert_72/ ) and numerous experiments including real-time quantitative polymerase chain reaction, terminal deoxynucleotidyltransferase dUTP nick end labeling, CCK-8, western blot, vasculogenesis and luciferase reporter assays were used to research the function and mechanism of miR-148a-3p in DR.

RESULTS

We constructed DR cell model by treating human retinal microvascular endothelial cells (HRECs) with different concentration gradients of high glucose (HG). Additionally, HG treatment reduced miR-148a-3p level in HRECs. In function, overexpression of miR-148a-3p caused an increase in cell viability and a decrease in cell apoptosis. Besides, miR-148a-3p overexpression led to a damage on blood-retinal barrier (BRB) and suppressed angiogenesis. In mechanism, miR-148a-3p specifically bound to 3' untranslated region of TGFB2 and FGF2. At least, rescue assays demonstrated that the inhibitive influence of miR-148a-3p mimics on BRB injury was offset by overexpression of TGFB2 and the attenuation of angiogenesis resulting from miR-148a-3p mimics was abrogated by overexpression of FGF2 CONCLUSIONS: In a word, we discovered that miR-148a-3p alleviated HG-induced DR by targeting TGFB2 and FGF2. This novel discovery indicated miR-148a-3p as a potential target for DR diagnosis or treatment.

MicroRNA Expression in the Aqueous Humor of Patients with Diabetic Macular Edema

We identified and compared secreted microRNA (miRNA) expression in aqueous humor (AH) and plasma samples among patients with: type 2 diabetes mellitus (T2D) complicated by non-proliferative diabetic retinopathy (DR) associated with diabetic macular edema (DME) (DME group: 12 patients); T2D patients without DR (D group: 8 patients); and non-diabetic patients (CTR group: 10 patients). Individual patient AH samples from five subjects in each group were profiled on TaqMan Low Density MicroRNA Array Cards. Differentially expressed miRNAs identified from profiling were then validated in single assay for all subjects. The miRNAs validated in AH were then evaluated in single assay in plasma. Gene Ontology (GO) analysis was conducted. From AH profiling, 119 mature miRNAs were detected: 86 in the DME group, 113 in the D group and 107 in the CTR group. miRNA underexpression in the DME group was confirmed in single assay for let-7c-5p, miR-200b-3p, miR-199a-3p and miR-365-3p. Of these four, miR-199a-3p and miR-365-3p were downregulated also in the plasma of the DME group. GO highlighted 54 validated target genes of miR-199a-3p, miR-200b-3p and miR-365-3p potentially implied in DME pathogenesis. Although more studies are needed, miR-200b-3p, let-7c-5p, miR-365-3p and miR-199a-3p represent interesting molecules in the study of DME pathogenesis.

Integrated analysis of lncRNA, miRNA and mRNA reveals novel insights into the fertility regulation of large white sows

Background

Improving sow fertility is extremely important as it can lead to increased reproductive efficiency and thus profitability for swine producers. There are considerable differences in fertility rates among individual animals, but the underlying molecular mechanisms remain unclear. In this study, by using different types of RNA libraries, we investigated the complete transcriptome of ovarian tissue during the luteal (L) and follicular (F) phases of the estrous cycle in Large White pigs with high (H) and low (L) fecundity, and performed a comprehensive analysis of long noncoding RNAs (lncRNAs), mRNAs and micro RNAs (miRNAs) from 16 samples by combining RNA sequencing (RNA-seq) with bioinformatics.

Results

In total, 24,447 lncRNAs, 27,370 mRNAs, and 216 known miRNAs were identified in ovarian tissues. The genomic features of lncRNAs, such as length distribution and number of exons, were further analyzed. We selected a threshold of P < 0.05 and |log₂ (fold change)| ≥ 1 to obtain the differentially expressed lncRNAs, miRNAs and mRNAs by pairwise comparison (LH vs. LL, FH vs. FL). Bioinformatics analysis of these differentially expressed RNAs revealed multiple significantly enriched pathways (P < 0.05) that were closely involved in the reproductive process, such as ovarian steroidogenesis, lysosome, steroid biosynthesis, and the estrogen and GnRH signaling pathways. Moreover, bioinformatics screening of differentially expressed miRNAs that share common miRNA response elements (MREs) with lncRNAs and their downstream mRNA targets were performed. Finally, we constructed lncRNA–miRNA–mRNA regulation networks. The key genes in these networks were verified by Reverse Transcription Real-time Quantitative PCR (RT-qRCR), which were consistent with the results from RNA-Seq data.

Conclusions

These results provide further insights into the fertility of pigs andcan contribute to further experimental investigation of the functions of these genes.

Long non-coding RNA VIM Antisense RNA 1 (VIM-AS1) sponges microRNA-29 to participate in diabetic retinopathy

AIMS

Long non-coding RNA (lncRNA) VIM Antisense RNA 1 (VIM-AS1) has been reported to be correlated with type 2 diabetes (T2D) susceptibility, while the roles of this lncRNA in T2D and its complications remain unclear. This study aimed to explore the role of VIM-AS1 in diabetic retinopathy (DR).

METHODS

Gene expression levels in both human specimens and in vitro cultivated cells were determined by qPCR and western blot. Overexpression experiments were performed to analyze gene interactions. Cell apoptosis after transfections was detected by cell apoptosis assay.

RESULTS

We found that VIM-AS1 was significantly downregulated in T2D patients in comparison with that in healthy controls. Specifically, the expression levels of VIM-AS1 were lowest among T2D patients complicated with DR. Bioinformatics analysis showed that VIM-AS1 can interact with microRNA 29 (miR-29), which is a critical player in high glucose-induced apoptosis of human retinal pigment epithelial cells (RPEs). Dual-luciferase assay also revealed the direct interaction between them. High glucose treatment led to upregulated miR-29 and downregulated VIM-AS1. However, overexpression of VIM-AS1 and miR-29 did not affect the expression of each other. Cell apoptosis analysis showed that overexpression of VIM-AS1 reduced the enhancing effects of miR-29 overexpression on RPEs cell proliferation.

CONCLUSIONS

Therefore, VIM-AS1 may sponge miR-29 to participate in DR.

Integrative analysis of competitive endogenous RNA network reveals the regulatory role of non-coding RNAs in high-glucose-induced human retinal endothelial cells

Background

Increasing evidence has suggested that non-coding RNAs (ncRNAs) play critical roles in the pathogenesis of diabetic retinopathy (DR), but their underlying mechanisms remain unclear. The purpose of this study was to determine latent key genes and to structure a competing endogenous RNA (ceRNA) regulatory network to discover the potential molecular mechanisms governing the effects of high glucose on human retinal endothelial cells (HRECs).

Methods

We obtained microarray data for long non-coding RNA (lncRNA) and mRNA of high-glucose-induced HREC samples from NCBI GEO datasets. The ceRNA network was screened using intersecting prediction results from miRcode, TargetScan, miRTarBase and miRDB. The protein–protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes and hub genes were obtained using the cytoHubba app. The ClusterProfiler package was applied for performing Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The expression of key RNAs was verified using the qRT-PCR method. A key ceRNA subnetwork was constructed based on the criticality of the genes and its binding sites were verified by luciferase reporter assay. The viability and apoptosis of HRECs were tested using the transfection of the miR-449c inhibitor.

Results

A total of 3,328 lncRNAs and 2,017 mRNAs were screened for differentially expressed (DE) profiles. The newly constructed ceRNA network was composed of 410 lncRNAs, 35 miRNAs and 122 mRNAs. The 10 hub genes were identified through the PPI network. GO and KEGG analysis revealed that DE mRNAs were mainly related to the positive regulation of the mRNA catabolic process, cell polarity, and the G1/S transition of mitotic and cell cycle signaling pathways. QRT-PCR was used to verify RNAs and the most important genes were screened out. A key ceRNA subnetwork OIP5-AS1/miR-449c/MYC was established. The binding site was verified by luciferase reporter assay. The expression levels of OIP5-AS1 and MYC increased after miR-449c inhibitor transfection, miR-449c decreased, HRECs activity increased, and apoptosis decreased, compared with the control group.

Conclusion

We successfully built the key ceRNA subnetwork, OIP5-AS1/miR-449c/MYC, by applying the GEO database for data analysis and mining. The results from the ceRNA network allow us to better understand the effect of ncRNAs on HRECs under hyperglycemic conditions and the pathogenesis of DR.

MicroRNA-199a-3p inhibits angiogenesis by targeting the VEGF/PI3K/AKT signalling pathway in an in vitro model of diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a major inducer of blindness and visual impairment. As a critical cause for DR, hyperglycaemia is able to trigger multiple biochemical alterations. MiRNAs, which contain various functions, can effectively regulate blood glucose levels. This research aims to confirm the roles of miRNA-199a-3p in the progression of angiogenesis in an in vitro model of DR.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was carried to determine the expression levels of miR-199a-3p and VEGF in both hRMECs and APRE-19 cells. The luciferase reporter assay was used to study the interaction between miR-199a-3p and VEGF. Western blot assay was conducted to examine the expression levels of VEGF and the PI3K/AKT signalling pathway. The cell proliferation capacity was detected via the CCK-8 test. The impact of miR-199a-3p on migration was determined using Transwell and wound healing assays. A Matrigel tube formation assay was employed to determine the vascular formation of hRMECs. Flow cytometry was used to determine cell apoptosis in the presence of LY294002 as a PI3K inhibitor.

RESULTS

Our results showed that high glucose (HG) decreased the relative expression level of miR-199a-3p but increased VEGF expression in hRMECs and APRE-19 cells. MiR-199a-3p inhibitor augmented cell growth, migration and angiogenesis of hRMECs. Moreover, upregulation of miR-199a-3p evidently alleviated the increases in cell proliferation, migration and angiogenesis caused by HG. In addition, the luciferase reporter assay indicated that miR-199a-3p directly targeted VEGF. The overexpression of miR-199a-3p obviously restrained the HG-stimulated PI3K/AKT signalling pathway and angiogenesis, which could be further inhibited by LY294002. Moreover, LY294002 could slightly ameliorate the miR-199a-3p inhibitor-stimulated PI3K/AKT signalling pathway and angiogenesis.

CONCLUSION

MiR-199a-3p upregulation ameliorated HG-stimulated angiogenesis of hRMECs by modulating the PI3K/AKT pathway through inhibiting VEGF. Although retinal neovascularization in vivo has not been studied, these in vitro findings provide more evidence for the role of miR-199a-3p upregulation against HG-induced angiogenesis.

Dysregulation of miR-210 is involved in the development of diabetic retinopathy and serves a regulatory role in retinal vascular endothelial cell proliferation

Background

Diabetic retinopathy is a common complication of diabetes mellitus (DM). The purpose of this study was to investigate the expression and clinical significance of miR-210 in DR patients and explore the regulatory effect of miR-210 on vascular endothelial cell function under high-glucose condition.

Methods

Quantitative real-time PCR was used to estimate miR-210 expression. A receiver operating characteristics curve (ROC) was plotted to evaluate the diagnostic value of miR-210. Human umbilical vein endothelial cells (HUVECs) were used and treated with high glucose (30 mM), and the cell proliferation was assessed by MTT assay.

Results

Serum expression of miR-210 was upregulated in DR patients compared with DM without DR patients and healthy controls. The expression of miR-210 in proliferative DR (PDR) patients was higher than non-proliferative DR (NPDR) patients. The increased serum miR-210 could be used to distinguish DR cases from healthy individuals and also simple DM patients, and can screen PDR cases from NPDR cases. The overexpression of miR-210 promoted HUVEC proliferation, while the knockdown of miR-210 resulted in the opposite effect under a high-glucose condition.

Conclusion

The data of this study demonstrated that serum increased miR-210 serves as a diagnostic biomarker in DR patients and may have the ability to predict DR development and severity. The regulatory effect of miR-210 on vascular endothelial cell proliferation under high-glucose condition, indicating its therapeutic potential in the treatment of diabetic vascular diseases.