LncRNA-MALAT1 promotes neovascularization in diabetic retinopathy through regulating miR-125b/VE-cadherin axis

Exosomal MALAT1 from macrophages treated with high levels of glucose upregulates LC3B expression via miR-204-5p downregulation

BACKGROUND

Metastasis-associated lung adenocarcinoma transcript 1 ( MALAT1 ) plays a critical role in the pathophysiology of diabetes-related complications. However, whether macrophage-derived MALAT1 affects autophagic activity under hyperglycemic conditions is unclear. Therefore, we investigated the molecular regulatory mechanisms of macrophage-derived MALAT1 and autophagy under hyperglycemic conditions.

METHODS

Hyperglycemia was induced by culturing macrophages in 25 mM glucose for 1 hour. Exosomes were extracted from the culture media. A rat model of carotid artery balloon injury was established to assess the effect of MALAT1 on vascular injury. Reverse transcription, real-time quantitative polymerase chain reaction, western blotting, immunohistochemical staining, and luciferase activity assays were performed.

RESULTS

Stimulation with high levels of glucose significantly enhanced MALAT1 expression in macrophage-derived exosomes. MALAT1 inhibited miR-204-5p expression in macrophage-derived exosomes under hyperglycemic conditions. siRNA-induced silencing of MALAT1 significantly reversed macrophage-derived exosome-induced miR-204-5p expression. Hyperglycemic treatment caused a significant, exosome-induced increase in the expression of the autophagy marker LC3B in macrophages. Silencing MALAT1 and overexpression of miR-204-5p significantly decreased LC3B expression induced by macrophage-derived exosomes. Overexpression of miR-204-5p significantly reduced LC3B luciferase activity induced by macrophage-derived exosomes. Balloon injury to the carotid artery in rats significantly enhanced MALAT1 and LC3B expression, and significantly reduced miR-204-5p expression in carotid artery tissue. Silencing MALAT1 significantly reversed miR-204-5p expression in carotid artery tissue after balloon injury. MALAT1 silencing or miR-204-5p overexpression significantly reduced LC3B expression after balloon injury.

CONCLUSION

This study demonstrated that hyperglycemia upregulates MALAT1 . MALAT1 suppresses miR-204-5p expression and counteracts the inhibitory effect of miR-204-5p on LC3B expression in macrophages to promote vascular disease.

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.

Insights into the defensive roles of lncRNAs during Mycoplasma pneumoniae infection

Mycoplasma pneumoniae causes respiratory tract infections, affecting both children and adults, with varying degrees of severity ranging from mild to life-threatening. In recent years, a new class of regulatory RNAs called long non-coding RNAs (lncRNAs) has been discovered to play crucial roles in regulating gene expression in the host. Research on lncRNAs has greatly expanded our understanding of cellular functions involving RNAs, and it has significantly increased the range of functions of lncRNAs. In lung cancer, transcripts associated with lncRNAs have been identified as regulators of airway and lung inflammation in a process involving protein complexes. An excessive immune response and antibacterial immunity are closely linked to the pathogenesis of M. pneumoniae. The relationship between lncRNAs and M. pneumoniae infection largely involves lncRNAs that participate in antibacterial immunity. This comprehensive review aimed to examine the dysregulation of lncRNAs during M. pneumoniae infection, highlighting the latest advancements in our understanding of the biological functions and molecular mechanisms of lncRNAs in the context of M. pneumoniae infection and indicating avenues for investigating lncRNAs-related therapeutic targets.

Classical and Innovative Evidence for Therapeutic Strategies in Retinal Dysfunctions

The human retina is a complex anatomical structure that has no regenerative capacity. The pathogenesis of most retinopathies can be attributed to inflammation, with the activation of the inflammasome protein platform, and to the impact of oxidative stress on the regulation of apoptosis and autophagy/mitophagy in retinal cells. In recent years, new therapeutic approaches to treat retinopathies have been investigated. Experimental data suggest that the secretome of mesenchymal cells could reduce oxidative stress, autophagy, and the apoptosis of retinal cells, and in turn, the secretome of the latter could induce changes in mesenchymal cells. Other studies have evidenced that noncoding (nc)RNAs might be new targets for retinopathy treatment and novel disease biomarkers since a correlation has been found between ncRNA levels and retinopathies. A new field to explore is the interaction observed between the ocular and intestinal microbiota; indeed, recent findings have shown that the alteration of gut microbiota seems to be linked to ocular diseases, suggesting a gut-eye axis. To explore new therapeutical strategies for retinopathies, it is important to use proper models that can mimic the complexity of the retina. In this context, retinal organoids represent a good model for the study of the pathophysiology of the retina.

LncRNA as a regulator in the development of diabetic complications

Diabetes is a metabolic disease characterized by hyperglycemia, which induces the production of AGEs, ROS, inflammatory cytokines, and growth factors, leading to the formation of vascular dysfunction and target organ damage, promoting the development of diabetic complications. Diabetic nephropathy, retinopathy, and cardiomyopathy are common complications of diabetes, which are major contributors to disability and death in people with diabetes. Long non-coding RNAs affect gene transcription, mRNA stability, and translation efficiency to influence gene expression for a variety of biological functions. Over the past decade, it has been demonstrated that dysregulated long non-coding RNAs are extensively engaged in the pathogenesis of many diseases, including diabetic complications. Thus, this review discusses the regulations of long non-coding RNAs on the primary pathogenesis of diabetic complications (oxidative stress, inflammation, fibrosis, and microvascular dysfunction), and some of these long non-coding RNAs may function as potential biomarkers or therapeutic targets for diabetic complications.

Expression of Long Non-Coding RNAs in Activated Human Retinal Vascular Endothelial Cells

PURPOSE

Retinal endothelial cell activation is a central event in non-infectious posterior uveitis. There is recent interest in long non-coding (lnc)RNA-targeted therapeutics for retinal diseases. We aimed to identify human retinal endothelial cell lncRNAs that might be involved in activation.

METHODS

Eleven candidate lncRNAs were identified: GAS5, KCNQ1OT1, LINC00294, MALAT1, MEG3, MIR155HG, NEAT1, NORAD, OIP5-AS1, SENCR, TUG1. Expression was assessed by RT-PCR in human retinal endothelial cells, at baseline and following activation with interleukin (IL)-1β and tumor necrosis factor (TNF)-α.

RESULTS

IL-1β significantly upregulated MEG3 and SENCR at 4 and 24 hours; LINC00294, NORAD, OIP5-AS1 and TUG1 at 24 hours; and MIR155HG at 4, 24 and 48 hours; but downregulated GAS5 at 24 and 48 hours. TNF-α significantly upregulated KCNQ1OT1, LINC00294, MEG3, NORAD and SENCR at 4 hours; SENCR and TUG1 at 24 hours; and MIR155HG at all time points.

CONCLUSIONS

Future studies involving manipulation of MIR155HG may be warranted to explore potential therapeutic applications for non-infectious posterior uveitis.

Potential roles of lncRNA MALAT1-miRNA interactions in ocular diseases

Long non-coding RNAs (lncRNAs) are non-protein coding transcripts that are longer than 200 nucleotides in length. LncRNAs are implicated in gene expression at the transcriptional, translational, and epigenetic levels, and thereby impact different cellular processes including cell proliferation, migration, apoptosis, angiogenesis, and immune response. In recent years, numerous studies have demonstrated the significant contribution of lncRNAs to the pathogenesis and progression of various diseases, such as stroke, heart disease, and cancer. Further investigations have shown that lncRNAs have altered expression patterns in ocular tissues and cell lines during pathological conditions. The pathogenesis of various ocular diseases, including glaucoma, cataract, corneal diseases, proliferative vitreoretinopathy, diabetic retinopathy, and retinoblastoma, is influenced by the involvement of specific lncRNAs which play a critical role in the development and progression of these diseases. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a well-researched lncRNA in the context of ocular diseases, which has been shown to exert its biological effects through several signaling pathways and downstream targets. The present review provides a comprehensive summary of the molecular mechanisms underlying the biological functions and roles of MALAT1 in ocular diseases.

Endoplasmic reticulum stress: molecular mechanism and therapeutic targets

The endoplasmic reticulum (ER) functions as a quality-control organelle for protein homeostasis, or "proteostasis". The protein quality control systems involve ER-associated degradation, protein chaperons, and autophagy. ER stress is activated when proteostasis is broken with an accumulation of misfolded and unfolded proteins in the ER. ER stress activates an adaptive unfolded protein response to restore proteostasis by initiating protein kinase R-like ER kinase, activating transcription factor 6, and inositol requiring enzyme 1. ER stress is multifaceted, and acts on aspects at the epigenetic level, including transcription and protein processing. Accumulated data indicates its key role in protein homeostasis and other diverse functions involved in various ocular diseases, such as glaucoma, diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, achromatopsia, cataracts, ocular tumors, ocular surface diseases, and myopia. This review summarizes the molecular mechanisms underlying the aforementioned ocular diseases from an ER stress perspective. Drugs (chemicals, neurotrophic factors, and nanoparticles), gene therapy, and stem cell therapy are used to treat ocular diseases by alleviating ER stress. We delineate the advancement of therapy targeting ER stress to provide new treatment strategies for ocular diseases.

Role of Lnc-RNAs in the Pathogenesis and Development of Diabetic Retinopathy

Important advances in diabetic retinopathy (DR) research and management have occurred in the last few years. Neurodegenerative changes before the onset of microvascular alterations have been well established. So, new strategies are required for earlier and more effective treatment of DR, which still is the first cause of blindness in working age. We describe herein gene regulation through Lnc-RNAs as an interesting subject related to DR. Long non-coding RNAs (Lnc-RNAs) are non-protein-coding transcripts larger than 200 nucleotides. Lnc-RNAs regulate gene expression and protein formation at the epigenetic, transcriptional, and translational levels and can impact cell proliferation, apoptosis, immune response, and oxidative stress. These changes are known to take part in the mechanism of DR. Recent investigations pointed out that Lnc-RNAs might play a role in retinopathy development as Metastasis-Associated Lung Adenocarcinoma Transcript (Lnc-MALAT1), Maternally expressed gene 3 (Lnc-MEG3), myocardial-infarction-associated transcript (Lnc-MIAT), Lnc-RNA H19, Lnc-RNA HOTAIR, Lnc-RNA ANRIL B-Raf proto-oncogene (Lnc-RNA BANCR), small nucleolar RNA host gene 16 (Lnc-RNA SNHG16) and others. Several molecular pathways are impacted. Some of them play a role in DR pathophysiology, including the PI3K-Akt signaling axis, NAD-dependent deacetylase sirtuin-1 (Sirti1), p38 mitogen-activated protein kinase (P38/mapk), transforming growth factor beta signaling (TGF-β) and nuclear factor erythroid 2-related factor 2 (Nrf2). The way Lnc-RNAs affect diabetic retinopathy is a question of great relevance. Performing a more in-depth analysis seems to be crucial for researchers if they want to target Lnc-RNAs. New knowledge on gene regulation and biomarkers will enable investigators to develop more specialized therapies for diabetic retinopathy, particularly in the current growing context of precision medicine.

Research progress on the pathogenesis of diabetic retinopathy

Diabetic retinopathy is one of the most common and serious microvascular complications of diabetes mellitus. There are many factors leading to diabetic retinopathy, and its pathogenesis is still unclear. At present, there are still no effective measures for the early treatment of diabetic retinopathy, and the treatment options available when diabetes progresses to advanced stages are very limited, and the treatment results are often unsatisfactory. Detailed studies on the molecular mechanisms of diabetic retinopathy pathogenesis and the development of new therapeutic agents are of great importance. This review describes the potential pathogenesis of diabetic retinopathy for experimental studies and clinical practice.

Biogenesis and function of exosome lncRNAs and their role in female pathological pregnancy

Preeclampsia, gestational diabetes mellitus, and recurrent spontaneous abortion are common maternal pregnancy complications that seriously endanger women's lives and health, and their occurrence is increasing year after year with a rejuvenation trend. In contrast to biomarkers found freely in tissues or body fluids, exosomes exist in a relatively independent environment and provide a higher level of stability. As backbone molecules, guidance molecules, and signaling molecules in the nucleus, lncRNAs can regulate gene expression. In the cytoplasm, lncRNAs can influence gene expression levels by modifying mRNA stability, acting as competitive endogenous RNAs to bind miRNAs, and so on. Exosomal lncRNAs can exist indefinitely and are important in intercellular communication and signal transduction. Changes in maternal serum exosome lncRNA expression can accurately and timely reflect the progression and regression of pregnancy-related diseases. The purpose of this paper is to provide a reference for clinical research on the pathogenesis, diagnosis, and treatment methods of pregnancy-related diseases by reviewing the role of exosome lncRNAs in female pathological pregnancy and related molecular mechanisms.

Galectin-1-dependent ceRNA network in HRMECs revealed its association with retinal neovascularization

BACKGROUND

Retinal neovascularization (RNV) is a leading cause of blindness worldwide. Long non-coding RNA (lncRNA) and competing endogenous RNA (ceRNA) regulatory networks play vital roles in angiogenesis. The RNA-binding protein galectin-1 (Gal-1) participates in pathological RNV in oxygen-induced retinopathy mouse models. However, the molecular associations between Gal-1 and lncRNAs remain unclear. Herein, we aimed to explore the potential mechanism of action of Gal-1 as an RNA-binding protein.

RESULTS

A comprehensive network of Gal-1, ceRNAs, and neovascularization-related genes was constructed based on transcriptome chip data and bioinformatics analysis of human retinal microvascular endothelial cells (HRMECs). We also conducted functional enrichment and pathway enrichment analyses. Fourteen lncRNAs, twenty-nine miRNAs, and eleven differentially expressed angiogenic genes were included in the Gal-1/ceRNA network. Additionally, the expression of six lncRNAs and eleven differentially expressed angiogenic genes were validated by qPCR in HRMECs with or without siLGALS1. Several hub genes, such as NRIR, ZFPM2-AS1, LINC0121, apelin, claudin-5, and C-X-C motif chemokine ligand 10, were found to potentially interact with Gal-1 via the ceRNA axis. Furthermore, Gal-1 may be involved in regulating biological processes related to chemotaxis, chemokine-mediated signaling, the immune response, and the inflammatory response.

CONCLUSIONS

The Gal-1/ceRNA axis identified in this study may play a vital role in RNV. This study provides a foundation for the continued exploration of therapeutic targets and biomarkers associated with RNV.

Long Non-Coding RNAs and Proliferative Retinal Diseases

Retinopathy refers to disorders that affect the retina of the eye, which are frequently caused by damage to the retina's vascular system. This causes leakage, proliferation, or overgrowth of blood vessels through the retina, which can lead to retinal detachment or breakdown, resulting in vision loss and, in rare cases, blindness. In recent years, high-throughput sequencing has significantly hastened the discovery of new long non-coding RNAs (lncRNAs) and their biological functions. LncRNAs are rapidly becoming recognized as critical regulators of several key biological processes. Current breakthroughs in bioinformatics have resulted in the identification of several lncRNAs that may have a role in retinal disorders. Nevertheless, mechanistic investigations have yet to reveal the relevance of these lncRNAs in retinal disorders. Using lncRNA transcripts for diagnostic and/or therapeutic purposes may aid in the development of appropriate treatment regimens and long-term benefits for patients, as traditional medicines and antibody therapy only provide temporary benefits that must be repeated. In contrast, gene-based therapies can provide tailored, long-term treatment solutions. Here, we will discuss how different lncRNAs affect different retinopathies, including age-related macular degeneration (AMD), diabetic retinopathy (DR), central retinal vein occlusion (CRVO), proliferative vitreoretinopathy (PVR), and retinopathy of prematurity (ROP), which can cause visual impairment and blindness, and how these retinopathies can be identified and treated using lncRNAs.

Aberrant lncRNA expression in patients with proliferative diabetic retinopathy: preliminary results from a single-center observational study

BACKGROUND

Diabetic retinopathy (DR) is a leading cause of blindness. Vision threat is particularly severe in patients with retinal neovascularization. However, little is known about the role of long noncoding RNAs (lncRNAs) in proliferative diabetic retinopathy (PDR). The goal of this study was to identify lncRNAs involved in PDR.

METHODS

We compared lncRNA expression profiles in the vitreous between patients with PDR and those with idiopathic macular hole (IMH) and between patients with PDR who had received anti-vascular endothelial growth factor (VEGF) therapy and those who had not. Vitreous samples from patients with PDR and IMH were screened for lncRNAs using microarray-based analysis, and quantitative real-time polymerase chain reaction (qRT-PCR) was used to confirm the microarray results. Bioinformatic analysis was also performed. Moreover, the effect of anti-VEGF therapy was investigated in vitreous samples of patients with PDR treated with anti-VEGF therapy and those who were not.

RESULTS

A total of 1067 differentially expressed noncoding RNA transcripts were found during screening in the vitreous humor of patients with PDR than in those with IMH. Five lncRNAs were subjected to qRT-PCR. RP11-573 J24.1, RP11-787B4.2, RP11-654G14.1, RP11-2A4.3, and RP11-502I4.3 were significantly downregulated; this was validated by the comparison using the microarray data. In addition, 835 differentially expressed noncoding RNA transcripts were found during screening in the vitreous humor of patients with PDR treated with anti-VEGF therapy compared with untreated PDR patients. RP4-631H13.2 was significantly upregulated, which is consistent with the trend of the microarray analysis.

CONCLUSIONS

There were systemic expression differences in the vitreous at the microarray level between patients with PDR and those with IMH and between patients with PDR after anti-VEGF treatment and those that did not receive anti-VEGF treatment. LncRNAs identified in the vitreous humor may be a novel research field for PDR.

Long non-coding RNAs in retinal neovascularization: current research and future directions

PURPOSE

Retinal neovascularization (RNV) is an intractable pathological hallmark of numerous ocular blinding diseases, including diabetic retinopathy, retinal vein occlusion, and retinopathy of prematurity. However, current therapeutic methods have potential side effects and limited efficacy. Thus, further studies on the pathogenesis of RNV-related disorders and novel therapeutic targets are critically required. Long non-coding RNAs (lncRNAs) have various functions and participate in almost all biological processes in living cells, such as translation, transcription, signal transduction, and cell cycle control. In addition, recent research has demonstrated critical modulatory roles of various lncRNAs in RNV. In this review, we summarize current knowledge about the expression and regulatory functions of lncRNAs related to the progression of pathological RNV.

METHODS

We searched databases such as PubMed and Web of Science to gather and review information from the published literature.

CONCLUSIONS

In general, lncRNA MEG3 attenuates RNV, thus protecting the retina from excessive and dysregulated angiogenesis under high glucose stress. In contrast, lncRNAs MALAT1, MIAT, ANRIL, HOTAIR, HOTTIP, and SNHG16, have been identified as causative molecules in the pathological progression of RNV. Comprehensive and in-depth studies of the roles of lncRNAs in RNV indicate that targeting lncRNAs may be an alternative therapeutic approach in the near future, enabling new options for attenuating RNV progression and treating RNV-related retinal diseases.

Current Insights into miRNA and lncRNA Dysregulation in Diabetes: Signal Transduction, Clinical Trials and Biomarker Discovery

Diabetes is one of the most frequently occurring metabolic disorders, affecting almost one tenth of the global population. Despite advances in antihyperglycemic therapeutics, the management of diabetes is limited due to its complexity and associated comorbidities, including diabetic neuropathy, diabetic nephropathy and diabetic retinopathy. Noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), are involved in the regulation of gene expression as well as various disease pathways in humans. Several ncRNAs are dysregulated in diabetes and are responsible for modulating the expression of various genes that contribute to the 'symptom complex' in diabetes. We review various miRNAs and lncRNAs implicated in diabetes and delineate ncRNA biological networks as well as key ncRNA targets in diabetes. Further, we discuss the spatial regulation of ncRNAs and their role(s) as prognostic markers in diabetes. We also shed light on the molecular mechanisms of signal transduction with diabetes-associated ncRNAs and ncRNA-mediated epigenetic events. Lastly, we summarize clinical trials on diabetes-associated ncRNAs and discuss the functional relevance of the dysregulated ncRNA interactome in diabetes. This knowledge will facilitate the identification of putative biomarkers for the therapeutic management of diabetes and its comorbidities. Taken together, the elucidation of the architecture of signature ncRNA regulatory networks in diabetes may enable the identification of novel biomarkers in the discovery pipeline for diabetes, which may lead to better management of this metabolic disorder.

Signaling by LncRNAs: Structure, Cellular Homeostasis, and Disease Pathology

The cellular signaling network involves co-ordinated regulation of numerous signaling molecules that aid the maintenance of cellular as well as organismal homeostasis. Aberrant signaling plays a major role in the pathophysiology of many diseases. Recent studies have unraveled the superfamily of long non-coding RNAs (lncRNAs) as critical signaling nodes in diverse signaling networks. Defective signaling by lncRNAs is emerging as a causative factor underlying the pathophysiology of many diseases. LncRNAs have been shown to be involved in the multiplexed regulation of diverse pathways through both genetic and epigenetic mechanisms. They can serve as decoys, guides, scaffolds, and effector molecules to regulate cell signaling. In comparison with the other classes of RNAs, lncRNAs possess unique structural modifications that contribute to their diversity in modes of action within the nucleus and cytoplasm. In this review, we summarize the structure and function of lncRNAs as well as their vivid mechanisms of action. Further, we provide insights into the role of lncRNAs in the pathogenesis of four major disease paradigms, namely cardiovascular diseases, neurological disorders, cancers, and the metabolic disease, diabetes mellitus. This review serves as a succinct treatise that could open windows to investigate the role of lncRNAs as novel therapeutic targets.

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.

Effect of LncRNA-MALAT1 on mineralization of dental pulp cells in a high-glucose microenvironment

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) belongs to the long non-coding RNA (LncRNA) family. LncRNA-MALAT1 is expressed in a variety of tissues and is involved in a variety of diseases and biological processes. Although LncRNA-MALAT1 is upregulated in a high-glucose microenvironment and may participate in odontogenic differentiation, the underlying mechanism is not yet well elucidated. Here, we show that MALAT1 was mainly expressed in the cytoplasm of dental pulp cells (DPCs) in situ hybridization. In addition, high levels of mineralization-related factors, namely, tumor growth factors β 1 and 2 (TGFβ-1 and TGFβ-2), bone morphogenetic proteins 2 and 4 (BMP2 and BMP4), bone morphogenetic protein receptor 1 (BMPR1), SMAD family member 2 (SMAD2), runt-related transcription factor 2 (RUNX2), Msh homeobox 2 (MSX2), transcription factor SP7 (SP7), alkaline phosphatase (ALP), dentin matrix acidic phosphoprotein 1 (DMP1), and dentin sialophosphoprotein (DSPP), were expressed, and MALAT1 was significantly overexpressed in DPCs 7 and 14 days after mineralization induction in a high-glucose microenvironment, but only TGFβ-1, BMP2, MSX2, SP7, ALP, and DSPP were significantly downregulated in DPCs after MALAT1 inhibition. MALAT1 may participate in the mineralization process of DPCs by regulating multiple factors (TGFβ-1, BMP2, MSX2, SP7, ALP, and DSPP).

MALAT1 regulates PCT expression in sepsis patients through the miR‐125b/STAT3 axis

Background

Procalcitonin (PCT) is an important marker in diagnosing sepsis. However, some other diseases can also cause an increase in PCT. PCT still has some limitations in the clinical application of diagnosing sepsis. Therefore, it is of great significance to clarify the regulatory mechanism of PCT expression in sepsis and provide new therapeutic targets for sepsis.

Methods

Blood samples from clinical patients were collected, and peripheral blood monocytes were isolated. Bioinformatics was performed to find the ceRNA regulatory network of STAT3/PCT. MALAT1 and miR‐125b were detected by qRT‐PCR. MALAT1 was located by fluorescence in situ hybridization (FISH) in U937 cells, and the regulatory relationship between MALAT1, miR‐125b, and STAT3 was verified by double luciferase activity report and RNA pull‐down assay. U937 cells were transfected with miR‐125b, and the effects of the MALAT1/miR‐125b/STAT3 pathway on gene and protein secretion levels of PCT were verified by qRT‐PCR, western blot, and ELISA.

Results

In the serum of sepsis patients and lipopolysaccharide(LPS)‐induced U937 cells, MALAT1, STAT3, and PCT gene expression levels were significantly increased, while miR‐125b expression level was decreased. FISH results showed that the MALAT1 transcript was mainly located in the nucleus. The double luciferase activity report and RNA pull‐down assay results suggested a targeted regulatory relationship between MALAT1, miR‐125b, and STAT3. LPS‐induced U937 cells transfection with MALAT1 siRNA decreased STAT3 protein expression and phosphorylation level and the expression of PCT. Co‐transfection with miR‐125b inhibitor effectively reversed this phenomenon.

Conclusions

MALAT1 could upregulate the expressions of STAT3 and PCT by targeted adsorption of miR‐125b.

Yiqi Tongluo Fang could preventive and delayed development and formation of diabetic retinopathy through antioxidant and anti-inflammatory effects

BACKGROUND

Yiqi Tongluo Fang (YQTLF) is an effective prescription for the treatment of diabetic retinopathy (DR), but its mechanism of action remains unclear.

METHOD

The content of YQTLF was determined using liquid and gas chromatography-mass spectrometry (LC-MS and GC-MS, respectively). Twenty-five Sprague Dawley (SD) rats were randomly selected as the normal control group. One hundred SD streptozotocin-induced diabetes (type 1) rats were randomly divided into diabetic control, diabetic+insulin+ calcium dobesilate (CaD), and diabetic+insulin+ YQTLF groups, with 25 rats in each group. Bodyweight level was measured every 2 weeks. After 12 weeks of gavage, the glucose levels, lipids, oxidative stress, inflammation, retinal histopathology, and the blood-retinal barrier were assessed in each group. The p38 MAPK pathway was changed to explore its internal mechanism. The measurement data were expressed as mean ± standard deviation, and different statistical methods were used according to a normal distribution, square error, or not.

RESULTS

A total of 1024 valid peaks were identified in YQTLF using GC-MS. YQTLF significantly lowered the fasting blood glucose levels in diabetic rats. YQTLF early inhibited changes in retinal histology, capillaries, cells, and tight junction proteins (such as ZO-1, occludin, claudin-5, and VE-cadherin) before the formation and development of DR. These findings correlated with the alleviation of glucolipid metabolism, inflammation, and oxidative stress. The lncRNA MALAT1 and the PRC 2/p38 MAPK-related pathway, such as the expression of EZH2, SUZ12, EED, p38 MAPK, MMP-9, and VEGFR, were also correlated.

CONCLUSION

We have demonstrated the molecular and cellular mechanisms underlying the preventive and delayed development and formation of DR. YQTLF prevents changes in dyslipidemia, retinal histology, capillaries, cells, and tight junction proteins. These protective effects appear to be linked to its antioxidant and anti-inflammatory effects, which prevent the activation of intracellular signaling pathways, such as the lncRNA MALAT1 and PRC 2/p38 MAPK-related pathway.

LncRNA THRIL promotes high glucose-induced proliferation and migration of human retina microvascular endothelial cells through enhancing autophagy

AIMS

Diabetes retinopathy (DR) is associated with retinal microvascular system injury induced by high glucose (HG). This study aims to explore the role and mechanism of long non-coding RNA THRIL in regulating cell proliferation and migration of human retina microvascular endothelial cells (hRMECs) under HG condition.

METHOD

The gene and protein expression were detetced by RT-PCR and western blot, respectively. Cell proliferation and migration of hRMECs were examined using MTT assay and Transwell assay, respectively. The interaction between miR-125b-5p and THRIL or autophagy-related gene 4D (ATG4D) was analyzed using luciferase activity assay.

RESULTS

THRIL expression was induced by HG in hRMECs. THRIL overexpression enhanced the proliferation and migration of hRMECs induced by HG, whereas THRIL silencing yielded the opposite results. Furthermore, THRIL overexpression induced autophagy activation, and inhibition of autophagy by 3-methyladenine abrogated the promotory effects of THRIL overexpression on cell proliferation and migration of hRMECs. Mechanismly, THRIL inhibited miR-125b-5p to upregulate the expression of ATG4D (an important autophagy-related gene), thereby promoting autophagy. Moreover, miR-125b-5p overexpression or ATG4D silencing alone abolished the promoting effects of THRIL overexpression on HG-induced autophagy, proliferation and migration of hRMECs.

CONCLUSIONS

THRIL promotes HG-induced cell proliferation and migration of hRMECs through activation of autophagy via the miR-125b-5p/ATG4D axis. THRIL may serve as a potential therapeutic target for DR.

Regulation of Oxidative Stress by Long Non-Coding RNAs in Vascular Complications of Diabetes

Diabetes mellitus is a well-known metabolic disorder with numerous complications, such as macrovascular diseases (e.g., coronary heart disease, diabetic cardiomyopathy, stroke, and peripheral vascular disease), microvascular diseases (e.g., diabetic nephropathy, retinopathy, and diabetic cataract), and neuropathy. Multiple contributing factors are implicated in these complications, and the accumulation of oxidative stress is one of the critical ones. Several lines of evidence have suggested that oxidative stress may induce epigenetic modifications that eventually contribute to diabetic vascular complications. As one kind of epigenetic regulator involved in various disorders, non-coding RNAs have received great attention over the past few years. Non-coding RNAs can be roughly divided into short (such as microRNAs; ~21–25 nucleotides) or long non-coding RNAs (lncRNAs; >200 nucleotides). In this review, we briefly discussed the research regarding the roles of various lncRNAs, such as MALAT1, MEG3, GAS5, SNHG16, CASC2, HOTAIR, in the development of diabetic vascular complications in response to the stimulation of oxidative stress.

Expression of Long Non-Coding RNA (lncRNA) SNHG5 in Patients with Refractory Diabetic Macular Edema and Its Regulatory Mechanism

BACKGROUND The aim of this study was to assess use of lncRNAs as biomarkers in serum and aqueous humor of patients with diabetic macular edema (DME). MATERIAL AND METHODS Optical coherence tomography and fundus photography were used to analyze the retinal features of the patients. RT-qPCR was used to analyze the differential expression of lncRNA snhg5 in patients who have idiopathic macular hole (MH), DME, or refractory DME. The relationship between SNHG5 and the clinical characteristics of the patients was analyzed. The effect of SNHG5 on the hyperplasia and apoptosis of human retino-microvascular endothelial cells (HRMECs) and its mechanism were analyzed in vitro. RESULTS Patients with idiopathic MH developed retinal nerve epithelium rupture and retinal fundus thickening, and patients with DME or refractory DME showed significant macular edema with hemorrhaging. The refractory DME patients improved after treatment but still showed significant macular edema and multiple laser scarring. SNHG5 expression was not only low in the atrial fluid and plasma in DME patients, but also lower in the refractory DME group compared to the idiopathic MH patients. SNHG5 expression in the aqueous humor and plasma was negatively correlated with disease duration, body mass index, and levels of fasting blood glucose, glycated hemoglobin, proteinuria, and glycosuria. In the in vitro experiments, SNHG5 expression was significantly downregulated in high glucose-induced HMECs. After SNHG5 overexpression, cell proliferation, angiogenesis, and VEGF-A protein levels were distinctly downregulated. CONCLUSIONS SNHG5 correlates with the development of DME and is a potential target for therapy.

Long Noncoding RNAs and Mitochondrial Homeostasis in the Development of Diabetic Retinopathy

Retinopathy is one of the most devastating complications of diabetes, which a patient fears the most. Hyperglycemic environment results in many structural, functional, molecular and biochemical abnormalities in the retina, and overproduction of mitochondrial superoxide, induced by hyperglycemic milieu, is considered to play a central role in the development of diabetic retinopathy. Expression of many genes associated with maintaining mitochondrial homeostasis is also altered. Recent research has shown that several long noncoding RNAs, RNAs with more than 200 nucleotides but without any reading frames, are aberrantly expressed in diabetes, and altered expression of these long noncoding RNAs is now being implicated in the development of diabetes and its complications including retinopathy. This review focuses the role of long noncoding RNAs in the development of diabetic retinopathy, with a special emphasis on the maintenance of mitochondrial homeostasis.

Long non-coding RNA MALAT1 enhances angiogenesis during bone regeneration by regulating the miR-494/SP1 axis

Bone regeneration is a coordinated process involving connections between blood vessels and osteocytes. Angiogenesis and osteogenesis are tightly connected throughout the progression of bone regeneration. This study aimed to explore the underlying mechanism of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)-regulated angiogenesis during bone regeneration. Gene and protein expression was detected by quantitative real-time PCR and western blot assay. Vascular endothelial growth factor (VEGFA) secretion was assessed by enzyme-linked immunosorbent assay. To evaluate the effect of osteogenic differentiation, alkaline phosphatase (ALP) and alizarin red staining assays were performed. Proliferation was detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Migration and angiogenesis were measured using Transwell and tube formation assays. A dual luciferase reporter assay was performed to confirm the binding relationship among MALAT1, miR-494, and specificity protein 1 (SP1). Expression levels of MALAT1, SP1, and VEGFA were elevated and miR-494 was suppressed in MC3T3-E1 cells after culture in osteogenic medium. MALAT1 knockdown suppressed the osteogenic differentiation of MC3T3-E1, since ALP activity, mineralized nodules, and expression of the osteodifferentiated markers runt-related transcription factor 2 and osterix were restrained. In addition, MALAT1 silencing inhibited angiogenesis during bone regeneration, as the proliferation, migration, and capillary tube formation of human umbilical vein endothelial cells were blocked. Furthermore, miR-494 was directly targeted by MALAT1 and regulated the SP1/Toll-like receptor 2 (TLR2)/bone morphogenetic protein 2 (BMP2) axis by targeting SP1. Furthermore, miR-494 overexpression inhibited angiogenesis and osteogenic differentiation. Moreover, SP1 overexpression or miR-494 inhibition rescued the regulatory effect of sh-MALAT1 on angiogenesis and osteogenic differentiation. Taken together, these findings indicate that MALAT1 promotes angiogenesis and osteogenic differentiation by targeting miR-494 and activating the SP1/TLR2/BMP2 pathway, suggesting a novel target for bone regeneration therapy by promoting angiogenesis.

Dissecting the Pathogenesis of Diabetic Retinopathy Based on the Biological ceRNA Network and Genome Variation Disturbance

Background

Diabetic retinopathy (DR) is the most important manifestation of diabetic microangiopathy. It is essential to explore the gene regulatory relationship and genomic variation disturbance of biological networks in DR progression.

Methods

In this study, we constructed a comprehensive lncRNA-mRNA ceRNA network of DR procession (CLMN) and explored its topological characteristics.

Results

Modular and functional analysis indicated that the organization of CLMN performed fundamental and specific functions in diabetes and DR pathology. The differential expression of hub ceRNA nodes and positive correlation reveals the highly connected ceRNA regulation and important roles in the regulating of DR pathology. A large proportion of SNPs in the TFBS, DHS, and enhancer regions of lncRNAs will affect lncRNA transcription and further cause expression variation. Some SNPs were found to disrupt the lncRNA functional elements such as miRNA target binding sites. These results indicate the complex nature of genotypic effects in the disturbing of CLMN and further contribute to gene expression variation and different disease phenotypes.

Conclusion

The identification of individual genomic variations and analysis of biological network disturbance by these genomic variations will help provide more personalized treatment plans and promote the development of precision medicine for DR.

Long non-coding RNAs in metabolic disorders: pathogenetic relevance and potential biomarkers and therapeutic targets

BACKGROUND

It has been suggested that dysregulation of long non-coding RNAs (lncRNAs) could be associated with the incidence and development of metabolic disorders.

AIM

Accordingly, this narrative review described the molecular mechanisms of lncRNAs in the development of metabolic diseases including insulin resistance, diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), cirrhosis, and coronary artery diseases (CAD). Furthermore, we investigated the up-to-date findings on the association of deregulated lncRNAs in the metabolic disorders, and potential use of lncRNAs as biomarkers and therapeutic targets.

CONCLUSION

LncRNAs/miRNA/regulatory proteins axis plays a crucial role in progression of metabolic disorders and may be used in development of therapeutic and diagnostic approaches.

Annexin A8 regulated by lncRNA-TUG1/miR-140-3p axis promotes bladder cancer progression and metastasis

Bladder cancer is the ninth most diagnosed cancer in the world. This study aims to investigate the role and mechanisms of the taurine-upregulated gene 1 (TUG1)/miR-140-3p/annexin A8 (ANXA8) axis in bladder cancer. Western blotting and qRT-PCR determined the expression levels of ANXA8, miR-140-3p, TUG1, and epithelial-mesenchymal transition (EMT) markers. RNA immunoprecipitation (RIP), luciferase assay, and RNA pull-down assay validated the association among ANXA8, miR-140-3p, and TUG1. The biological functions were determined by colony formation, Annexin V-fluorescein isothiocyanate (FITC)/propidium (PI) staining, and transwell assays. Xenograft tumorigenesis detected tumor growth and metastasis in vivo. Pathological analysis was examined by hematoxylin and eosin (H&E) and immunohistochemistry (IHC) analyses. ANXA8 was elevated in bladder tumors and cells. Knockdown of ANXA8 suppressed cell growth, migration, invasion, and EMT in UMUC-3 and T24 cells. ANXA8 was determined as a miR-140-3p target gene. Overexpression of miR-140-3p suppressed cell proliferation, migration, invasion, and EMT via targeting ANXA8. TUG1 promoted ANXA8 expression via sponging miR-140-3p. Silencing of miR-140-3p or ANXA8 overexpression abrogated the tumor-suppressive effects of TUG1 silencing on bladder cancer cell growth and metastasis. The TUG1/miR-140-3p/ANXA8 axis was also implicated in tumor growth and lung metastasis in vivo. TUG1 promotes bladder cancer progression and metastasis through activating ANXA8 by sponging miR-140-3p, which sheds light on the mechanisms of bladder cancer pathogenesis.

Potential of Long Non-Coding RNAs in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of visual impairment in the aging population with poorly known pathogenesis and lack of effective treatment. Age and family history are the strongest AMD risk factors, and several loci were identified to contribute to AMD. Recently, also the epigenetic profile was associated with AMD, and some long non-coding RNAs (lncRNAs) were shown to involve in AMD pathogenesis. The Vax2os1/2 (ventral anterior homeobox 2 opposite strand isoform 1) lncRNAs may modulate the balance between pro- and anti-angiogenic factors in the eye contributing to wet AMD. The stress-induced dedifferentiation of retinal pigment epithelium cells can be inhibited by the ZNF503-AS1 (zinc finger protein 503 antisense RNA 2) and LINC00167 lncRNAs. Overexpression of the PWRN2 (Prader-Willi region non-protein-coding RNA 2) lncRNA aggravated RPE cells apoptosis and mitochondrial impairment induced by oxidative stress. Several other lncRNAs were reported to exert protective or detrimental effects in AMD. However, many studies are limited to an association between lncRNA and AMD in patients or model systems with bioinformatics. Therefore, further works on lncRNAs in AMD are rational, and they should be enriched with mechanistic and clinical studies to validate conclusions obtained in high-throughput in vitro research.

Exosomes from mesenchymal stem cells expressing microribonucleic acid-125b inhibit the progression of diabetic nephropathy via the tumour necrosis factor receptor-associated factor 6/Akt axis

Diabetic nephropathy (DN) seriously threatens the health of patients with diabetes. Moreover, it has been reported that mesenchymal stem cell (MSC)-derived exosomal miRNAs can modulate the progression of multiple diseases, including DN. It has been suggested that miR-125b is involved in DN. However, the biological functions of exosomal miRNAs, especially miR-125b, in DN are still unclear. To establish a DN model in vitro, we used a model of human embryonic kidney epithelial cells (HKCs) injury induced by high glucose (HG). Then, miR-125b was delivered to the model cells in vitro via MSC-derived exosomes (MSC-Exos), and the effect of exosomal miR-125b on HKCs apoptosis was evaluated by flow cytometry. qRT-PCR or western blotting was performed to measure miR-125b or tumour necrosis factor receptor-associated factor 6 (TRAF6) expression in HKC. The effect of MSC-Exos on HKCs apoptosis after miR-125b knockdown was determined by flow cytometry. Moreover, dual-luciferase reporter assays were used to determine the targeting relationship between miR-125b and TRAF6 in HKCs. Our data revealed that MSC-Exos increased HG-induced autophagy in HKCs and reversed HKCs apoptosis. Moreover, our study found that miR-125b was enriched in MSC-Exos and directly targeted TRAF6 in HKCs. In addition, exosomally transferred miR-125b inhibited the apoptosis of HG-treated HKCs by mediating Akt signalling. In summary, MSC-derived exosomal miR-125b induced autophagy and inhibited apoptosis in HG-treated HKCs via the downregulation of TRAF6. Therefore, our study provided a new idea for DN treatment.

Research progress of lncRNAs in diabetic retinopathy

Diabetic retinopathy (DR), which is known as a severe complication of type 2 diabetes mellitus, can cause varying degrees of damage to visual acuity. The pathogenesis of DR is multifactorial and not fully understood. Many previous research studies have revealed that an aberrant level of some long non-coding RNAs (lncRNAs) may accelerate the development of DR. These lncRNAs are regulatory factors and research related to them is always underway. In this review, we will update several types of lncRNAs based on the previous studies which are related to the development of DR and discuss its potential mechanisms of action and connections. Generally, the review will help us know more about lncRNAs and provide directions for future research related to DR.

Suppressing long noncoding RNA OGRU ameliorates diabetic retinopathy by inhibition of oxidative stress and inflammation via miR-320/USP14 axis

Long noncoding RNAs (lncRNAs) are important regulators in various diseases including diabetic retinopathy (DR). In this study, DR patients exhibited significantly increased expression of serum LncRNA-OGRU compared with normal individuals. Streptozotocin (STZ)-challenged rats with DR also had higher OGRU expression in retinas than that of the control group, which was confirmed in Müller cells upon high glucose (HG) stimulation. OGRU knockdown remarkably decreased vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) expression in HG-incubated Müller cells. HG-induced inflammatory response and oxidative stress in vitro were markedly mitigated by OGRU knockdown through restraining IκBɑ/nuclear factor kappa beta (NF-κB) and improving nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways, respectively. Further studies indicated that OGRU suppression greatly restored miR-320 expression, and a negative correlation between them was detected in DR patients. We also found that miR-320 over-expression considerably restrained TGF-β1 signaling, and hindered inflammation and reactive oxygen species (ROS) production in HG-stimulated Müller cells. Additionally, OGRU knockdown or miR-320 over-expression could dramatically down-regulate ubiquitin-specific peptidase 14 (USP14) expression levels in HG-incubated Müller cells, and miR-320 could directly target USP14. Notably, OGRU/miR-320 axis-mediated TGF-β1 signaling, inflammation and ROS were largely dependent on USP14. Intriguingly, our results showed that USP14 directly interacted with transforming growth factor-beta type 1 receptor (TβR1), and impeded TβR1 ubiquitination and degradation. Furthermore, USP14 could also facilitate IκBɑ deubiquitination and degradation, exacerbating IκBɑ phosphorylation and NF-κB activation. Finally, our in vivo studies confirmed that OGRU knockdown considerably ameliorated DR progression in STZ-challenged rats through mediating the mechanisms observed in vitro. Collectively, these findings implicated that LncRNA-OGRU mediated DR progression through competing for miR-320 to regulate USP14 expression, and thus LncRNA-OGRU/miR-320/USP14 axis may be considered as a therapeutic target for DR treatment.

Long non-coding RNAs and cancer metastasis: Molecular basis and therapeutic implications

Cancer metastasis, defined by the epithelial to mesenchymal transition (EMT) of tumor cells, disseminates from the primary site to progressively colonize in distant tissues, and accounts for most cancer-associated deaths. However, studies on the molecular basis of cancer metastasis are still in their infancy. Besides genetic mutations, accumulating evidence indicates that epigenetic alterations also contribute in a major way to the refractory nature of cancer metastasis. Considered as one of the essential epigenetic regulators, long non-coding RNAs (lncRNAs) can act as signaling regulators, decoys, guides and scaffolds, modulating key molecules in every step of cancer metastasis including dissemination of carcinoma cells, intravascular transit, and metastatic colonization. Although still having limited clinical application, it is encouraging to witness that several lncRNAs, including CCAT1 and HOTAIR, are under clinical evaluation as potential biomarkers for cancer staging and assessment of metastatic potential. In this review, we focus on the molecular mechanisms underlying lncRNAs in the regulation of cancer metastasis and discuss their clinical potential as novel therapeutic targets as well as their diagnostic and prognostic significance for cancer treatment. Gaining clear insights into the detailed molecular basis underlying lncRNA-modulated cancer metastasis may provide previously unrecognized diagnostic and therapeutic strategies for metastatic patients.

Scutellaria barbata D. Don Polysaccharides Inhibit High Glucose-Induced Proliferation and Angiogenesis of Retinal Vascular Endothelial Cells

PURPOSE

The traditional Chinese medicine Scutellaria barbata D. Don (S. barbata) has been reported to exhibit anti-cancer and anti-inflammation activities. The ethanol extract of S. barbata has been confirmed to attenuate diabetic retinopathy (DR). This study aimed to investigate the effects and underlying mechanisms of the polysaccharides isolated from S. barbata (PSB) on the proliferation and angiogenesis of retinal vascular endothelial cells (RVECs) in DR.

METHODS

Human RVECs (HRVECs) were cultured in normal glucose (NG, 5.5 mM), mannitol (MA, 30 mM), high glucose (HG, 30 mM) and HG plus 40 μg/mL PSB, respectively. Then, cell proliferation, migration and angiogenesis were evaluated. The cell proliferation was also estimated in the presence of SLIGKV, which was used to induce the phosphorylation of ERK (p-ERK).

RESULTS

PSB reduced normal and HG-induced HRVECs cell viability in a concentration-dependent manner. The protein expression of proliferating cell nuclear antigen (PCNA) and proliferating antigen KI67 (Ki67), the migration rate and tube formation ability, which were increased by HG treatment, were significantly decreased by PSB. PSB also inhibited the phosphorylation of Raf, MEK and ERK in HG-stimulated HRVECs. Moreover, the application of SLIGKV recovered cell viability and the expression of p-ERK, PCNA and Ki67, in HG plus PSB-treated cells. Finally, the HG-enhanced expression of VE-cadherin, Frizzed, β-catenin, MMP-2 and MMP-9 was all reversed by PSB.

CONCLUSION

PSB could inhibit HG-induced HRVECs proliferation, migration and neovascularization, and these effects might work through blocking the activation of MEK/ERK pathway and VEGF/VE-cadherin axis.

miRNA, lncRNA and circRNA: Targeted Molecules Full of Therapeutic Prospects in the Development of Diabetic Retinopathy

Diabetic retinopathy (DR) is a common diabetic complication and the main cause of blindness worldwide, which seriously affects the quality of life of patients. Studies have shown that noncoding RNA (ncRNA) has distinct differentiated expression in DR and plays an important role in the occurrence and development of DR. ncRNAs represented by microRNAs (miRNAs), lncRNAs (lncRNAs), and circRNAs (circRNAs) have been shown to be widely involved in the regulation of gene expression and affect multiple biological processes of retinopathy. This article will review three RNAs related to the occurrence and development of DR on the basis of previous studies (especially their effects on retinal microangiopathy, retinal pigment epithelial cells, and retinal nerve cells) and discuss their underlying mechanisms and connections. Overall, this review will help us better understand the role of ncRNAs in the occurrence and development of DR and provide ideas for exploring potential therapeutic directions and targets.

Long Noncoding RNA MALAT1 and Regulation of the Antioxidant Defense System in Diabetic Retinopathy

The retina experiences increased oxidative stress in diabetes, and the transcriptional activity of Nrf2, which is critical in regulating many antioxidant genes, is decreased. The nuclear movement/transcriptional activity of Nrf2 is mediated by its intracellular inhibitor Keap1, and retinal Keap1 levels are increased in diabetes. Gene expression is also regulated by long noncoding RNAs (LncRNAs). Our aim was to investigate the role of LncRNA MALAT1 in the regulation of Keap1-Nrf2-antioxidant defense in diabetic retinopathy. LncRNA MALAT1 expression (quantitative real-time PCR, immunofluorescence, and RNA sequencing), its interactions with Keap1 (FACS), Keap1-Nrf2 interactions, and transcription of the antioxidant response genes (immunofluorescence and nuclear RNA sequencing) were investigated in retinal endothelial cells exposed to high glucose. Glucose increased LncRNA MALAT1 levels by increasing Sp1 transcription factor binding at its promoter. Downregulation of LncRNA MALAT1 by its siRNA prevented glucose-induced increase in Keap1 and facilitated Nrf2 nuclear translocation and antioxidant gene transcription. Retinal microvessels from streptozotocin-induced diabetic mice and human donors with diabetic retinopathy also presented similar increases in LncRNA MALAT1 and its interactions with Keap1 and decreases in Nrf2-mediated antioxidant defense genes. Thus, LncRNA MALAT1, via Keap1-Nrf2, regulates antioxidant defense in diabetic retinopathy. Inhibition of LncRNA MALAT1 has potential to protect the retina from oxidative damage and to prevent or slow down diabetic retinopathy.

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.

Inhibition of hsa_circ_0002570 suppresses high-glucose-induced angiogenesis and inflammation in retinal microvascular endothelial cells through miR-1243/angiomotin axis

Diabetic retinopathy (DR) is the most severe microvascular complication of diabetes and a major cause of visual impairment and blindness. However, the treatment for DR is still limited. Our study aimed to explore the role of circular RNA_0002570 in DR. First, we predicted the potential microRNA and mRNA that could bind to circ_0002570 and identified the miR-1243 and angiomotin gene; then, we used RT-PCR and Western blot to measure their expression. Next, we evaluated the abilities of proliferation, migration, and angiogenesis in vitro in human retinal microvascular endothelial cells (hRMECs) by CCK-8, transwell assay, and tube formation assay, respectively. To analyze the relationship among miR-1243, circ_0002570, and angiomotin, RNA pull-down and luciferase assay were performed. Our results showed that, in DR patients and high-glucose-induced hRMECs, miR-1243, circ_0002570, and angiomotin were all abnormally expressed. MiR-1243 could directly and competitively bind to both circ_0002570 and angiomotin mRNA to inhibit their expression. Moreover, circ_0002570 suppressed the abilities of proliferation, migration, and angiogenesis in hRMECs induced by high glucose, which was dependent on miR-1243-angiomotin axis. Furthermore, circ_0002570 could upregulate angiomotin by targeting miR-1243 to mediate the dysfunction of hRMECs induced by high glucose. In conclusion, circ_0002570 might serve as a potential target for diagnosis and treatment for DR.

Role of Nrf2 in MALAT1/ HIF-1α loop on the regulation of angiogenesis in diabetic foot ulcer

Diabetic non healing wounds often result in significant morbidity and mortality. The number of effective targets to detect these wounds are meagre. Slow lymphangiogenesis is one of the complex processes involved in impaired healing of wounds. Long non coding RNAs (lncRNAs) have been importantly recognized for their role in pathological conditions. Multiple studies highlighting the role of lncRNAs in the regulation of several biological processes and complex diseases. Herein, we investigated the role of lncRNA Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in the progression of diabetic foot ulcer (DFU). We report a significant reduction in the expression of lncRNA MALAT1 in the infected DFU subjects which was positively correlated with the expression of angiogenic factors such as Nrf2, HIF-1α and VEGF. Further, expression of pro-inflammatory markers TNF-α and IL-6 were found to be increased while, the expression of anti-inflammatory marker IL-10 was decreased in infected DFU tissues. Involvement of lncRNA MALAT1 in angiogenesis in EA.hy926 cells was demonstrated by silencing the expression of Nrf2, HIF-1α, and VEGF through interference mediated by MALAT1. In addition, its inflammatory role was demonstrated by decreased expression of TNF-α, IL-6 and not affecting the expression of IL-10. Further, CRISPR-Cas9 knock out of Nrf2 decreased the expression of lncRNA MALAT1, HIF-1α and VEGF which revealed the association of Nrf2 in regulating MALAT1/HIF-1α loop through positive feedback mechanism. Collectively, our results suggested the role of Nrf2 on MALAT1/HIF-1α loop in the regulation of angiogenesis, which could act as a novel target in the treatment of diabetic wounds.

Circular RNA COL1A2 promotes angiogenesis via regulating miR-29b/VEGF axis in diabetic retinopathy

AIMS

The dysregulation of circular RNAs (circRNAs) has been implicated in the progression of diabetic retinopathy (DR). This study aims to explore the role and underlying mechanism of hsa_circ_0081108 (circCOL1A2) in DR.

MATERIALS AND METHODS

circCOL1A2, vascular endothelial growth factor (VEGF) and miR-29b expression levels in human retinal microvascular endothelial cells (hRMECs) were detected by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blotting. The biological functions of hRMECs were evaluated by MTT, transwell, tube formation, and vascular permeability assays, respectively. The interaction between miR-29b and circCOL1A2/VEGF was determined by dual luciferase assay. The release of VEGF was examined by ELISA. The in vivo role of circCOL1A2 was further verified in streptozotocin (STZ)-induced DR in mice. The pathological changes and VEGF expression in retinal tissues were detected by hematoxylin and eosin (HE) and immunohistochemical staining.

KEY FINDINGS

High glucose (HG) challenge led to increased circCOL1A2, VEGF, MMP-2, MMP-9 levels, but decreased miR-29b level in hRMECs. In addition, circCOL1A2 sponged miR-29b to promote VEGF expression. Silencing of circCOL1A2 inhibited HG-induced proliferation, migration, angiogenesis and vascular permeability of hRMECs via enhancing miR-29b expression. Moreover, circCOL1A2/miR-29b axis participated in HG-induced increase in angiogenesis-related protein expression. Finally, circCOL1A2 knockdown suppressed angiogenesis via regulating miR-29b/VEGF axis in DR mice.

SIGNIFICANCE

circCOL1A2 facilities angiogenesis during the pathological progression of DR via regulating miR-29b/VEGF axis, suggesting that targeting circCOL1A2 may be a potential treatment for DR.

Identification of Susceptibility Modules and Genes for Cardiovascular Disease in Diabetic Patients Using WGCNA Analysis

OBJECTIVE

To identify susceptibility modules and genes for cardiovascular disease in diabetic patients using weighted gene coexpression network analysis (WGCNA).

METHODS

The raw data of GSE13760 were downloaded from the Gene Expression Omnibus (GEO) website. Genes with a false discovery rate < 0.05 and a log2 fold change ≥ 0.5 were included in the analysis. WGCNA was used to build a gene coexpression network, screen important modules, and filter the hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed for the genes in modules with clinical interest. Genes with a significance over 0.2 and a module membership over 0.8 were used as hub genes. Subsequently, we screened these hub genes in the published genome-wide SNP data of cardiovascular disease. The overlapped genes were defined as key genes.

RESULTS

Fourteen gene coexpression modules were constructed via WGCNA analysis. Module greenyellow was mostly significantly correlated with diabetes. The GO analysis showed that genes in the module greenyellow were mainly enriched in extracellular matrix organization, extracellular exosome, and calcium ion binding. The KEGG analysis showed that the genes in the module greenyellow were mainly enriched in antigen processing and presentation, phagosome. Fifteen genes were identified as hub genes. Finally, HLA-DRB1, LRP1, and MMP2 were identified as key genes.

CONCLUSION

This was the first study that used the WGCNA method to construct a coexpression network to explore diabetes-associated susceptibility modules and genes for cardiovascular disease. Our study identified a module and several key genes that acted as essential components in the etiology of diabetes-associated cardiovascular disease, which may enhance our fundamental knowledge of the molecular mechanisms underlying this disease.

Knockdown of NEAT1 exerts suppressive effects on diabetic retinopathy progression via inactivating TGF-β1 and VEGF signaling pathways

Diabetic retinopathy (DR) is complication resulted from Type 2 diabetes mellitus. Accumulating evidence has proved the functions of long noncoding RNAs (lncRNAs) in the progression of DR. Recent reports exert the numerous regulatory functions of lncRNA nuclear-enriched abundant transcript 1 (NEAT1) in various diseases. However, its implications in DR remain barely known. Therefore, this study was carried out to explore the role of NEAT1 in high-glucose (HG)-triggered injury of human retinal endothelial cells (hRECs). Here, we found the NEAT1 level was significantly elevated in patients with DR, in the retina of diabetic rats and mice. Meanwhile, hRECs under HG stimuli also exhibited an increase of NEAT1. Moreover, the loss of NEAT1 enhanced hRECs proliferation and repressed HG-induced apoptosis, which was accompanied by an upregulation of Bcl-2 and a downregulation of Bax. Subsequently, the knockdown of NEAT1 obviously reduced HG-triggered oxidative stress injury in hRECs. It was reflected that intracellular reactive oxygen species and malondialdehyde level induced by HG were repressed by NEAT1 downregulation, while superoxide dismutase activity was increased. In addition, decreased NEAT1 repressed the inflammatory processes effectively as indicated by the inactivation of inflammatory cytokines Cox-2, interleukin-6, and tumor necrosis factor-α. Furthermore, vascular endothelial growth factor A (VEGF) and transforming growth factor-β1 (TGF-β1) expression in patients with DR, DR rats, and HG-incubated hRECs was obviously increased. The silence of NEAT1 could reduce the enhanced expression of VEGF and TGF-β1 induced by HG. Hence, we concluded NEAT1 might contribute to the development of DR through activating TGF-β1 and VEGF.

The protein Deleted in Breast Cancer-1 (DBC1) regulates vascular response and formation of aortic dissection during Angiotensin II infusion

Cardiovascular diseases are among the main causes of morbimortality in the adult population. Among them, hypertension is a leading cause for stroke, heart disease and kidney failure. Also, as a result of arterial wall weakness, hypertension can lead to the development of dissecting aortic aneurysms, a rare but often fatal condition if not readily treated. In this work, we investigated the role of DBC1 in the regulation of vascular function in an ANGII-induced hypertension mouse model. We found that WT and DBC1 KO mice developed hypertension in response to ANGII infusion. However, DBC1 KO mice showed increased susceptibility to develop aortic dissections. The effect was accompanied by upregulation of vascular remodeling factors, including MMP9 and also VEGF. Consistent with this, we found decreased collagen deposition and elastic fiber fragmentation, suggesting that increased expression of MMPs in DBC1 KO mice weakens the arterial wall, promoting the formation of aortic dissections during treatment with ANGII. Finally, DBC1 KO mice had reduced cell proliferation in the intima-media layer in response to ANGII, paralleled with an impairment to increase wall thickness in response to hypertension. Furthermore, VSMC purified from DBC1 KO mice showed impaired capacity to leave quiescence, confirming the in vivo results. Altogether, our results show for the first time that DBC1 regulates vascular response and function during hypertension and protects against vascular injury. This work also brings novel insights into the molecular mechanisms of the development of aortic dissections.

Involvement of lncRNAs and Macrophages: Potential Regulatory Link to Angiogenesis

Macrophages are involved in angiogenesis, an essential process for organ growth and tissue repair, and could contribute to the pathogenesis of angiogenesis-related diseases such as malignant tumors and diabetic retinopathy. Recently, long noncoding RNAs (lncRNAs) have been proved to be important in cell differentiation, organismal development, and various diseases of pathological angiogenesis. Moreover, it has been indicated that numerous lncRNAs exhibit different functions in macrophage infiltration and polarization and regulate the secretion of inflammatory cytokines released by macrophages. Therefore, the focus of macrophage-related lncRNAs could be considered to be a potential method in therapeutic targeting angiogenesis-related diseases. This review mainly summarizes the roles played by lncRNAs which associated with macrophages in angiogenesis. The possible mechanisms of the regulatory link between lncRNAs and macrophages in various angiogenesis-related diseases were also discussed.

LncRNA TDRG1-Mediated Overexpression of VEGF Aggravated Retinal Microvascular Endothelial Cell Dysfunction in Diabetic Retinopathy

Purpose

Diabetic retinopathy (DR), a neurovascular disease, is one of the leading causes of blindness in working-age adults. Long noncoding RNAs (lncRNAs) have attracted attention as indicators for DR. This study aimed to characterize the role of lncRNA human testis development-related gene 1 (TDRG1) and its modulation of vascular endothelial growth factor (VEGF) in deteriorating DR.

Methods

Tissue samples were obtained from patients with epiretinal membranes (EMs) or proliferative DR, and human retinal microvascular endothelial cells (HRECs) were cultured with high-glucose medium to mimic DR as the in vitro model. The expression of lncRNA TDRG1 and VEGF was determined by immunofluorescence staining, Western blotting, and RT-qPCR. Transfection of small-interfering RNA was conducted to knock down target gene expression. HREC functions were evaluated by cell viability, fluorescein isothiocyanate (FITC)-dextran extravasation, migration, and tube formation assays under different conditions.

Results

LncRNA TDRG1 and VEGF were found to be co-expressed and significantly upregulated in fibrovascular membranes (FVMs) from DR patients compared to those from EM patients. In the in vitro model, hyperglycemic treatment markedly increased the expression of lncRNA TDRG1 and VEGF at the mRNA and protein levels, which promoted cell proliferation and migration, enhanced permeability, and disrupted tube formation of HRECs. However, knockdown of lncRNA TDRG1 or VEGF notably decreased the expression of VEGF and reversed the impaired functions of high-glucose-treated HRECs.

Conclusions

LncRNA TDRG1 promoted microvascular cell dysfunction via upregulating VEGF in the progression of DR and may serve as a potential therapeutic target in DR treatment.

Transthyretin Upregulates Long Non-Coding RNA MEG3 by Affecting PABPC1 in Diabetic Retinopathy

The aim of the study was to demonstrate how transthyretin (TTR) could affect long non-coding RNA (lncRNA) of maternally expressed gene 3 (MEG3) and play important roles in diabetic retinopathy (DR). A DR model in C57BL/6 mice was established after intraperitoneal injection of streptozotocin (STZ). After intravitreal injection with TTR pAAV vector, MEG3 short hairpin RNA (shRNA), scrambled shRNA, or MEG3, retinal imaging, retinal trypsin digestion, and fundus vascular permeability tests were performed. Cell counting kit-8 (CCK8), transwell, and Matrigel assays were employed to detect the proliferation and migration of human retinal microvascular endothelial cells (hRECs). The binding between long non-coding RNA of maternally expressed gene 3 (lncRNA-MEG3) and microRNA-223-3p (miR-223-3p) was observed by using luciferase reporter assays, while co-immunoprecipitation (co-IP) was employed to confirm the interaction between TTR and the target. In the DR mice model, retinal vascular leakage and angiogenesis were repressed by overexpressing TTR. In vitro, the added TTR promoted the level of lncRNA-MEG3 by interacting with poly (A) binding protein cytoplasmic 1 (PABPC1), and then repressed proliferation and angiogenesis of hRECs. In vivo, silencing or overexpressing lncRNA-MEG3 significantly affected retinal vascular phenotypes. Additionally, the interaction between lncRNA-MEG3 and miR-223-3p was confirmed, and silencing of miR-223-3p revealed similar effects on hRECs as overexpression of lncRNA-MEG3. In summary, in the DR environment, TTR might affect the lncRNA MEG3/miR-223-3p axis by the direct binding with PABPC1, and finally repress retinal vessel proliferation.