Long noncoding RNA Hotair facilitates retinal endothelial cell dysfunction in diabetic retinopathy

Lnc-216 regulates the miR-143-5p /MMP2 signaling axis aggravates retinal endothelial cell dysfunction

PURPOSE

Diabetic retinopathy (DR) is a serious retinal vascular disease that affects many individuals in their prime working years. The present research aimed at whether and how LOC681216 (LNC-216) is involved in retinal vascular dysfunction under diabetic conditions.

METHODS

Rat retinal microvascular endothelial cells (RRMECs) treated with high glucose (HG) were used for functional analysis. Gene expression analysis was conducted using the Clariom D Affymetrix platform. The wound healing, transwell, and vascular tube formation assays were used to identify the migration, invasion, and tube formation capability of RRMECs. The dual-luciferase reporter confirmed the binding interaction between miR-143-5p and LNC-216 or matrix metallopeptidase 2 (MMP2).

RESULTS

Lnc-216 was upregulated in RRMECs treated with HG. Lnc-216 knockdown markedly suppressed the tube formation, cell migration, and wound healing of cultured RRMECs under HG conditions. Mechanistically, Lnc-216 acted as a miR-143-5p sponge to affect the biological activity of miR-143-5p, which led to increased expression of matrix metallopeptidase 2 (MMP2).

CONCLUSIONS

Lnc-216 attenuates diabetic retinal vascular dysfunction through the miR-143-5p/MMP2 axis, providing a potential therapeutic strategy for DR.

The role of long noncoding RNAs in ocular angiogenesis and vascular oculopathy

BACKGROUND

Long noncoding RNAs (lncRNAs) are RNA transcripts over 200 nucleotides in length that do not code for proteins. Initially considered a genomic mystery, an increasing number of lncRNAs have been shown to have vital roles in physiological and pathological conditions by regulating gene expression through diverse mechanisms depending on their subcellular localization. Dysregulated angiogenesis is responsible for various vascular oculopathies, including diabetic retinopathy, retinopathy of prematurity, age-related macular degeneration, and corneal neovascularization. While anti-VEGF treatment is available, it is not curative, and long-term outcomes are suboptimal, and some patients are unresponsive. To better understand these diseases, researchers have investigated the role of lncRNAs in regulating angiogenesis and models of vascular oculopathies. This review summarizes recent research on lncRNAs in ocular angiogenesis, including the pro-angiogenic lncRNAs ANRIL, HOTAIR, HOTTIP, H19, IPW, MALAT1, MIAT, NEAT1, and TUG1, the anti-angiogenic lncRNAs MEG3 and PKNY, and the human/primate specific lncRNAs lncEGFL7OS, discussing their functions and mechanisms of action in vascular oculopathies.

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.

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.

Non-coding RNAs in the pathophysiology of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is the largest unmet clinical need in cardiovascular medicine. Despite decades of research, the treatment option for HFpEF is still limited, indicating our ongoing incomplete understanding on the underlying molecular mechanisms. Non-coding RNAs, comprising of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are non-protein coding RNA transcripts, which are implicated in various cardiovascular diseases. However, their role in the pathogenesis of HFpEF is unknown. Here, we discuss the role of miRNAs, lncRNAs and circRNAs that are involved in the pathophysiology of HFpEF, namely microvascular dysfunction, inflammation, diastolic dysfunction and cardiac fibrosis. We interrogated clinical evidence and dissected the molecular mechanisms of the ncRNAs by looking at the relevant in vivo and in vitro models that mimic the co-morbidities in patients with HFpEF. Finally, we discuss the potential of ncRNAs as biomarkers and potential novel therapeutic targets for future HFpEF treatment.

The ideal treatment timing for diabetic retinopathy: the molecular pathological mechanisms underlying early-stage diabetic retinopathy are a matter of concern

Diabetic retinopathy (DR) is a prevalent complication of diabetes, significantly impacting patients' quality of life due to vision loss. No pharmacological therapies are currently approved for DR, excepted the drugs to treat diabetic macular edema such as the anti-VEGF agents or steroids administered by intraocular route. Advancements in research have highlighted the crucial role of early intervention in DR for halting or delaying disease progression. This holds immense significance in enhancing patients' quality of life and alleviating the societal burden associated with medical care costs. The non-proliferative stage represents the early phase of DR. In comparison to the proliferative stage, pathological changes primarily manifest as microangiomas and hemorrhages, while at the cellular level, there is a loss of pericytes, neuronal cell death, and disruption of components and functionality within the retinal neuronal vascular unit encompassing pericytes and neurons. Both neurodegenerative and microvascular abnormalities manifest in the early stages of DR. Therefore, our focus lies on the non-proliferative stage of DR and we have initially summarized the mechanisms involved in its development, including pathways such as polyols, that revolve around the pathological changes occurring during this early stage. We also integrate cutting-edge mechanisms, including leukocyte adhesion, neutrophil extracellular traps, multiple RNA regulation, microorganisms, cell death (ferroptosis and pyroptosis), and other related mechanisms. The current status of drug therapy for early-stage DR is also discussed to provide insights for the development of pharmaceutical interventions targeting the early treatment of DR.

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.

Pharmacological roles of lncRNAs in diabetic retinopathy with a focus on oxidative stress and inflammation

Diabetic retinopathy (DR) is a complication caused by abnormal glucose metabolism, which affects the vision and quality of life of patients and severely impacts the society at large.DR has a complex pathogenic process. Evidence from multiple studies have shown that oxidative stress and inflammation play pivotal roles in DR.Additionally, with the rapid development of various genetic detection methods, the abnormal expression of long non-coding RNAs (lncRNAs) have been confirmed to promote the development of DR.Research has demonstrated the potential of lncRNAs as ideal biomarkers and theranostic targets in DR. In this narrative review, we will focus on the research results on mechanisms underlying DR, list lncRNAs confirmed to be closely related to these mechanisms, and discuss their potential clinical application value and limitations.

Epigenetic modifications and metabolic memory in diabetic retinopathy: beyond the surface

Epigenetics focuses on DNA methylation, histone modification, chromatin remodeling, noncoding RNAs, and other gene regulation mechanisms beyond the DNA sequence. In the past decade, epigenetic modifications have drawn more attention as they participate in the development and progression of diabetic retinopathy despite tight control of glucose levels. The underlying mechanisms of epigenetic modifications in diabetic retinopathy still urgently need to be elucidated. The diabetic condition facilitates epigenetic changes and influences target gene expression. In this review, we summarize the involvement of epigenetic modifications and metabolic memory in the development and progression of diabetic retinopathy and propose novel insights into the treatment of diabetic retinopathy.

Lnc_000048 Promotes Histone H3K4 Methylation of MAP2K2 to Reduce Plaque Stability by Recruiting KDM1A in Carotid Atherosclerosis

Stabilizing and inhibiting plaque formation is a key challenge for preventing and treating ischemic stroke. KDM1A-mediated histone modifications, which involved in the development of training immunity, ultimately exacerbate the outcomes of inflammation. Although lncRNAs can recruit KDM1A to participate in histone methylation modification and regulate inflammation, cell proliferation, and other biological processes, little is known about the role of KDM1A-lncRNA interaction during atherosclerosis. The present study sought to delineate the effect of the interaction between lnc_000048 and KDM1A on plaque rupture in carotid atherosclerosis, as well as the potential mechanism. Our results revealed that lnc_000048 reduced the activity of histone demethylase and activated MAP2K2 expression by interacting with KDM1A. Furthermore, upregulated lnc_000048 indirectly regulated ERK phosphorylation by MAP2K2 and eventually activated the inflammatory response through the MAPK pathway, which was involved in atherosclerosis. Importantly, our study using ApoE-/- mice confirmed the regulatory role of lnc_000048 in promoting inflammation and collagen degradation in atherosclerotic plaques. These results suggest that targeting the lnc_000048 /KDM1A/MAP2K2/ERK axis may be a promising strategy for preventing atherosclerosis.

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.

Oxidative stress-induced lncRNA CYLD-AS1 promotes RPE inflammation via Nrf2/miR-134-5p/NF-κB signaling pathway

Oxidative stress-induced damage to and dysfunction of retinal pigment epithelium (RPE) cells are important pathogenetic factors of age-related macular degeneration (AMD); however, the underlying molecular mechanism is not fully understood. Long noncoding RNAs (lncRNAs) have important roles in various biological processes. In this study, using an oxidative damage model in RPE cells, we identified a novel oxidation-related lncRNA named CYLD-AS1. We further revealed that the expression of CYLD-AS1 was increased in RPEs during oxidative stress. Depletion of CYLD-AS1 promoted cell proliferation and mitochondrial function and protected RPE cells against hydrogen peroxide (H₂ O₂ )-induced damage. Mechanistically, CYLD-AS1 also regulated the expression of NRF2, which is related to oxidative stress, and NF-κB signaling pathway members, which are related to inflammation. Remarkably, these two signaling pathways were mediated by the CYLD-AS1 interactor miR-134-5p. Moreover, exosomes secreted by CYLD-AS1 knockdown RPE cells had a lower proinflammatory effect than those secreted by control cells. In summary, our study revealed that CYLD-AS1 affects the oxidative stress-related and inflammatory functions of RPE cells by sponging miR-134-5p to mediate NRF2/NF-κB signaling pathway activity, suggesting that targeting CYLD-AS1 could be a promising strategy for the treatment of AMD and related diseases.

Potential epigenetic molecular regulatory networks in ocular neovascularization

Neovascularization is one of the many manifestations of ocular diseases, including corneal injury and vascular diseases of the retina and choroid. Although anti-VEGF drugs have been used to effectively treat neovascularization, long-term use of anti-angiogenic factors can cause a variety of neurological and developmental side effects. As a result, better drugs to treat ocular neovascularization are urgently required. There is mounting evidence that epigenetic regulation is important in ocular neovascularization. DNA methylation and histone modification, non-coding RNA, and mRNA modification are all examples of epigenetic mechanisms. In order to shed new light on epigenetic therapeutics in ocular neovascularization, this review focuses on recent advances in the epigenetic control of ocular neovascularization as well as discusses these new mechanisms.

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.

Epigenetic modification mechanism of histone demethylase KDM1A in regulating cardiomyocyte apoptosis after myocardial ischemia-reperfusion injury

Hypoxia and reoxygenation (H/R) play a prevalent role in heart-related diseases. Histone demethylases are involved in myocardial injury. In this study, the mechanism of the lysine-specific histone demethylase 1A (KDM1A/LSD1) on cardiomyocyte apoptosis after myocardial ischemia-reperfusion injury (MIRI) was investigated. Firstly, HL-1 cells were treated with H/R to establish the MIRI models. The expressions of KDM1A and Sex Determining Region Y-Box Transcription Factor 9 (SOX9) in H/R-treated HL-1 cells were examined. The cell viability, markers of myocardial injury (LDH, AST, and CK-MB) and apoptosis (Bax and Bcl-2), and Caspase-3 and Caspase-9 protein activities were detected, respectively. We found that H/R treatment promoted cardiomyocyte apoptosis and downregulated KDM1A, and overexpressing KDM1A reduced apoptosis in H/R-treated cardiomyocytes. Subsequently, tri-methylation of lysine 4 on histone H3 (H3K4me3) level on the SOX9 promoter region was detected. We found that KDM1A repressed SOX9 transcription by reducing H3K4me3. Then, HL-1 cells were treated with CPI-455 and plasmid pcDNA3.1-SOX9 and had joint experiments with pcDNA3.1-KDM1A. We disclosed that upregulating H3K4me3 or overexpressing SOX9 reversed the inhibitory effect of overexpressing KDM1A on apoptosis of H/R-treated cardiomyocytes. In conclusion, KDM1A inhibited SOX9 transcription by reducing the H3K4me3 on the SOX9 promoter region and thus inhibited H/R-induced apoptosis of cardiomyocytes.

Long noncoding RNA PVT1 regulates the proliferation and apoptosis of ARPE-19 cells in vitro via the miR-1301-3p/KLF7 axis

Diabetic retinopathy (DR) as a frequent diabetic microvascular complication shows signs in one-third of diabetic patients. Long non-coding RNAs (lncRNAs) have drawn increasing attention because of their regulatory roles in DR. LncRNA plasmacytoma variant translocation 1 (PVT1) is documented to be upregulated in diabetes-related diseases, while its effects in DR remains unexplored. ARPE-19 cells under the treatment of high-glucose (HG) were used as DR cell models. The gene expression in ARPE-19 cells was examined using RT-qPCR. The viability and apoptosis of ARPE-19 cells were determined by MTT and TUNEL assays. The levels of inflammation-associated proteins or mRNA were measured using western blot. Luciferase reporter assay and RNA pull down assay were conducted for the exploration of the underlying mechanism of PVT1. PVT1 was revealed to be upregulated in DR cell models. Silencing of PVT1 promoted the viability and inhibited apoptosis of HG-stimulated ARPE-19 cells. The results revealed that PVT1 can bind with miR-1301-3p. PVT1 negatively modulated miR-1301-3p expression. Additionally, KLF7 was targeted by miR-1301-3p. PVT1 upregulated KLF7 expression by binding with miR-1301-3p. The silenced PVT1-mediated influence on cell viability and cell apoptosis was rescued by overexpression of KLF7. PVT1 suppresses proliferation and promotes apoptosis of ARPE-19 cells treated with HG in vitro by binding with miR-1301-3p to upregulate KLF7.

Association of Polymorphisms within HOX Transcript Antisense RNA (HOTAIR) with Type 2 Diabetes Mellitus and Laboratory Characteristics: A Preliminary Case-Control Study

Type 2 diabetes mellitus (T2DM) is a complex heterogeneous disease resulting from the environment and genetic interactions. Lately, genetic association studies have shown that polymorphisms in long noncoding RNAs (lncRNAs) are associated with T2DM susceptibility. This preliminary study is aimed at investigating if HOX transcript antisense RNA (HOTAIR) polymorphisms contribute to T2DM development. Five hundred clinically diagnosed T2DM cases and 500 healthy controls were recruited from the southeast Iranian population. Genomic DNA was isolated from nucleated blood cells and genotyped for MspI (C/T) (rs920778) and AluI (A/G) (rs4759314) polymorphisms using the PCR-RFLP technique. For genotyping rs12826786 C/T and rs1899663 G/T variants, ARMS-PCR method was applied. Our findings indicated that HOTAIR rs920778 C/T, rs12826786 C/T, and rs4759314 A/G polymorphisms have a significant positive association with T2DM, while a negative association was observed between rs1899663 G/T T2DM susceptibility. Significant associations were also observed between rs920778 C/T and HDL-C as well as s4759314 A/G and both FBS and LDL-C in T2DM patients. Haplotype analysis indicated that the CGCG, CTTG, TGTA, and TTTG haplotypes of rs920778/rs1899663/rs12826786/rs4759314 significantly enhanced T2DM risk by 1.47, 1.96, 2.81, and 4.80 folds, respectively. No strong linkage disequilibrium was found between the four HOTAIR SNPs. We firstly reported that HOTAIR rs1899663 G/T, rs12826786 C/T, rs4759314 A/G, and rs920778 C/T polymorphisms might influence T2DM susceptibility by modulating different signaling pathways and could be regarded as potential prognostic markers in T2DM patients.

HOTAIR-Loaded Mesenchymal Stem/Stromal Cell Extracellular Vesicles Enhance Angiogenesis and Wound Healing

Chronic wounds remain a substantial source of morbidity worldwide. An emergent approach that may be well-suited to induce the complex, multicellular processes such as angiogenesis that are required for wound repair is the use of extracellular vesicles (EVs). EVs contain a wide variety of proteins and nucleic acids that enable multifactorial signaling. Here, the capability of EVs is leveraged to be engineered via producer cell modification to investigate the therapeutic potential of EVs from mesenchymal stem/stromal cells (MSCs) transfected to overexpress long non-coding RNA HOX transcript antisense RNA (HOTAIR). HOTAIR is previously shown by the authors' group to be critical in mediating angiogenic effects of endothelial cell EVs, and MSCs are chosen as EV producer cells for this study due to their widely reported intrinsic angiogenic properties. The results indicate that MSCs overexpressing HOTAIR (HOTAIR-MSCs) produce EVs with increased HOTAIR content that promote angiogenesis and wound healing in diabetic (db/db) mice. Further, endothelial cells exposed to HOTAIR-MSC EVs exhibit increased HOTAIR content correlated with upregulation of the angiogenic protein vascular endothelial growth factor. Thus, this study supports EV-mediated HOTAIR delivery as a strategy for further exploration toward healing of chronic wounds.

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.

Dexmedetomidine inhibits endoplasmic reticulum stress to suppress pyroptosis of hypoxia/reoxygenation-induced intestinal epithelial cells via activating the SIRT1 expression

Dexmedetomidine (Dex) can protect the intestine against ischemia/reperfusion (I/R)-induced injury. Sirtuin 1 (SIRT1) pathway, which could be activated by Dex, was reported to inhibit I/R injury. Pyroptosis plays an important role in intestinal diseases. We aimed to investigate whether Dex could attenuate pyroptosis of hypoxia/reoxygenation (H/R)-induced intestinal epithelial cells via activating SIRT1. The intestinal epithelial cell line IEC-6 with or without SIRT1 knockdown after H/R treatment was exposed to Dex, then cell viability, endoplasmic reticulum stress (ERS), apoptosis, pyroptosis, inflammatory cytokines production and SIRT1 expression were detected. Results showed that Dex treatment had no significant effect on IEC-6 cell viability but rescued the H/R-reduced cell viability. The expression of proteins involved in ERS including Grp78, Gadd153 and caspase 12 was enhanced upon H/R stimulation, but was reversely reduced by Dex. The cell apoptosis increased by H/R was also decreased by Dex. Additionally, Dex inhibited pyroptosis and inflammation, which were markedly promoted upon H/R stimulation. The expression of SIRT1, which was reduced after H/R treatment was also partially rescued by Dex. Finally, the above effects of Dex were all blocked by SIRT1 knockdown. In conclusion, Dex could inhibit H/R-induced intestinal epithelial cells ERS, apoptosis and pyroptosis via activating SIRT1 expression.

LncRNA XIST restrains the activation of Müller cells and inflammation in diabetic retinopathy via stabilizing SIRT1

BACKGROUND

Recent studies have provided strong evidence that lncRNAs play a functional regulatory role in diabetic retinopathy (DR). The purpose of this study was to investigate the effect of long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) in DR.

METHODS

A DR mouse model was established by intraperitoneal injection of streptozotocin (STZ), and then the mouse retinal Müller cells (mMCs) were isolated from retina tissues of mice. Human retinal Müller cell line (HMCs) and mMCs and were treated with high glucose (HG) to simulate an in vitro DR model. XIST expression was detected by qRT-PCR. Next, XIST overexpression was performed in mMCs and HMCs to examine its effect on the activation of Müller cells and production of pro-inflammatory cytokines. Subsequently, the interaction between XIST and SIRT1 was verified, and the ubiquitination level of SIRT1 as well as the stability of SIRT1 protein were assessed.

RESULTS

XIST was down-regulated in retinal tissues of DR mice and HG-induced HMCs. Overexpression of XIST inhibited HG-induced activation of mMCs and HMCs, and reduced the production of pro-inflammatory cytokines. XIST promoted SIRT1 expression via interacting with SIRT1 and inhibiting the ubiquitination of SIRT1. Furthermore, SIRT1 silencing partly abrogated the effect of XIST overexpression on the activation of mMCs and HMCs as well as the production of pro-inflammatory cytokines induced by HG.

CONCLUSION

We concluded that XIST restrained the activation of Müller cells and the production of pro-inflammatory cytokines via stabilizing SIRT1.

The Role of HIF1α-PFKFB3 Pathway in Diabetic Retinopathy

Diabetic retinopathy (DR) is the leading cause of blindness for adults in developed countries. Both microvasculopathy and neurodegeneration are implicated in mechanisms of DR development, with neuronal impairment preceding microvascular abnormalities, which is often underappreciated in the clinic. Most current therapeutic strategies, including anti-vascular endothelial growth factor (anti-VEGF)-antibodies, aim at treating the advanced stages (diabetic macular edema and proliferative diabetic retinopathy) and fail to target the neuronal deterioration. Hence, new therapeutic approach(es) intended to address both vascular and neuronal impairment are urgently needed. The hypoxia-inducible factor 1α (HIF1α)-6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) pathway is critically implicated in the islet pathology of diabetes. Recent evidence highlighted the pathway relevance for pathologic angiogenesis and neurodegeneration, two key aspects in DR. PFKFB3 is key to the sprouting angiogenesis, along with VEGF, by determining the endothelial tip-cell competition. Also, PFKFB3-driven glycolysis compromises the antioxidative capacity of neurons leading to neuronal loss and reactive gliosis. Therefore, the HIF1α-PFKFB3 signaling pathway is unique as being a pervasive pathological component across multiple cell types in the retina in the early as well as late stages of DR. A metabolic point-of-intervention based on HIF1α-PFKFB3 targeting thus deserves further consideration in DR.

LncRNA-HOTAIR promotes endothelial cell pyroptosis by regulating the miR-22/NLRP3 axis in hyperuricaemia

Long non‐coding RNA (lncRNA) plays an important role in the renal inflammatory response caused by hyperuricaemia. However, the underlying molecular mechanisms through which lncRNA is involved in endothelial injury induced by hyperuricaemia remain unclear. In this study, we investigated the regulatory role of lncRNA‐HOTAIR in high concentration of uric acid (HUA)–induced renal injury. We established hyperuricaemia mouse model and an in vitro uric acid (UA)–induced human umbilical vein endothelial cell (HUVEC) injury model. In HUA‐treated HUVECs and hyperuricaemia mice, we observed increased HOTAIR and decreased miR‐22 expression. The expression of pyroptosis‐associated protein (NLRP3, Caspase‐1, GSDMD‐N, GSDMD‐FL) was increased. The release of LDH, IL‐1β and IL‐18 in cell supernatants and the sera of model mice was also increased. The proliferation of HUVECs stimulated by HUA was significantly inhibited, and the number of TUNEL‐positive cells in hyperuricaemia mouse kidney was increased. Bioinformatics analysis and luciferase reporter and RIP assays confirmed that HOTAIR promoted NLRP3 inflammasome activation by competitively binding miR‐22. In gain‐ or loss‐of‐function experiments, we found that HOTAIR and NLRP3 overexpression or miR‐22 knock down activated the NLRP3 inflammasome and promoted pyroptosis in HUA‐treated HUVECs, while NLRP3 and HOTAIR knockdown or a miR‐22 mimic exerted the opposite effects. Furthermore, in vivo experiments validated that HOTAIR knockdown alleviated renal inflammation in hyperuricaemia mice. In conclusion, we demonstrated that in hyperuricaemia, lncRNA‐HOTAIR promotes endothelial cell pyroptosis by competitively binding miR‐22 to regulate NLRP3 expression.

MiR-195 inhibits the ubiquitination and degradation of YY1 by Smurf2, and induces EMT and cell permeability of retinal pigment epithelial cells

The dysregulated microRNAs (miRNAs) are involved in diabetic retinopathy progression. Epithelial mesenchymal transition (EMT) and cell permeability are important events in diabetic retinopathy. However, the function and mechanism of miR-195 in EMT and cell permeability in diabetic retinopathy remain largely unclear. Diabetic retinopathy models were established using streptozotocin (STZ)-induced diabetic mice and high glucose (HG)-stimulated ARPE-19 cells. Retina injury was investigated by hematoxylin-eosin (HE) staining. EMT and cell permeability were analyzed by western blotting, immunofluorescence, wound healing, and FITC-dextran assays. MiR-195 expression was detected via qRT-PCR. YY1, VEGFA, Snail1, and Smurf2 levels were detected via western blotting. The interaction relationship was analyzed via ChIP, Co-IP, or dual-luciferase reporter assay. The retina injury, EMT, and cell permeability were induced in STZ-induced diabetic mice. HG induced EMT and cell permeability in ARPE-19 cells. MiR-195, YY1, VEGFA, and Snail1 levels were enhanced, but Smurf2 abundance was reduced in STZ-induced diabetic mice and HG-stimulated ARPE-19 cells. VEGFA knockdown decreased Snail1 expression and attenuated HG-induced EMT and cell permeability. YY1 silence reduced VEGFA and Snail1 expression, and mitigated HG-induced EMT and cell permeability. YY1 could bind with VEGFA and Snail1, and it was degraded via Smurf2-mediated ubiquitination. MiR-195 knockdown upregulated Smurf2 to decrease YY1 expression and inhibited HG-induced EMT and cell permeability. MiR-195 targeted Smurf2, increased expression of YY1, VEGFA, and Snail1, and promoted HG-induced EMT and cell permeability. MiR-195 promotes EMT and cell permeability of HG-stimulated ARPE-19 cells by increasing VEGFA/Snail1 via inhibiting the Smurf2-mediated ubiquitination of YY1.

The Long Non-Coding RNA HOTAIR Is a Critical Epigenetic Mediator of Angiogenesis in Diabetic Retinopathy

Purpose

Diabetic retinopathy (DR) remains a pressing issue worldwide. Abnormal angiogenesis is a distinct vascular lesion in DR, and research has established that vascular endothelial growth factor A (VEGF-A) is a primary mediator of such changes. However, limitations in current anti-VEGF therapies suggest that our understanding of molecular networks underlying ocular angiogenesis remains far from complete. Based on our long non-coding RNA (lncRNA) array analyses, HOX antisense intergenic RNA (HOTAIR) was identified as one of the top upregulated lncRNAs in high glucose-cultured human retinal endothelial cells (HRECs). Given the well-documented roles of HOTAIR in cancer, no studies have examined the epigenetic implications of HOTAIR in DR, and we investigated such relationships herein.

Methods

We used HRECs exposed to various glucose concentrations and epigenetic modulators to examine HOTAIR, angiogenic, and DR-related molecular markers. Oxidative stress, angiogenesis, and mitochondrial dysfunction were assessed. Retinal tissues of diabetic rodents and the vitreous humor and serum of patients with proliferative DR were also investigated.

Results

Hyperglycemia significantly augmented HOTAIR expression in HRECs and promoted angiogenesis, oxidative damage, and mitochondrial aberrations. Similarly, vitreous humor and serum from proliferative DR patients and retinas from diabetic animals demonstrated increased HOTAIR expression compared to non-diabetic controls. HOTAIR knockdown protected against glucose-induced increases of angiogenic and diabetes-associated molecules in the retina. Mechanistically, we showed that HOTAIR exerts its capabilities by preventing oxidative stress and modulating epigenetic pathways involving histone methylation, histone acetylation, DNA methylation, and transcription factors.

Conclusions

Our findings suggest that HOTAIR is a critical lncRNA in the pathogenesis of DR and may potentially be important for diagnostic and therapeutic targeting.

Noncoding RNAs involved in DNA methylation and histone methylation, and acetylation in diabetic vascular complications

Diabetes is a metabolic disorder and its incidence is still increasing. Diabetic vascular complications cause major diabetic mobility and include accelerated atherosclerosis, nephropathy, retinopathy, and neuropathy. Hyperglycemia contributes to the pathogenesis of diabetic vascular complications via numerous mechanisms including the induction of oxidative stress, inflammation, metabolic alterations, and abnormal proliferation of EC and angiogenesis. In the past decade, epigenetic modifications have attracted more attention as they participate in the progression of diabetic vascular complications despite controlled glucose levels and regulate gene expression without altering the genomic sequence. DNA methylation and histone methylation, and acetylation are vital epigenetic modifications and their underlying mechanisms in diabetic vascular complication are still urgently needed to be investigated. Non-coding RNAs (nc RNAs) such as micro RNAs (miRNAs), long non-coding RNA (lncRNAs), and circular RNAs (circ RNAs) were found to exert transcriptional regulation in diabetic vascular complication. Although nc RNAs are not considered as epigenetic components, they are involved in epigenetic modifications. In this review, we summarized the investigations of non-coding RNAs involved in DNA methylation and histone methylation and acetylation. Their cross-talks might offer novel insights into the pathology of diabetic vascular complications.