Long noncoding RNA TUG1 contributes to cerebral ischaemia/reperfusion injury by sponging mir-145 to up-regulate AQP4 expression

The Roles of Non-coding RNA Targeting Astrocytes in Cerebral Ischemia

Astrocytes are key targets for treating cerebral ischemia in the central nervous system. Non-coding RNAs (ncRNAs) participate in the pathological processes of astrocytes in cerebral ischemia. Recent reports suggest that ncRNAs ameliorate the outcome of cerebral ischemia by mediating astrocytes' inflammatory reaction, oxidative stress, excitotoxicity, autophagy, and apoptosis. Reconstructing cellular systems might offer a promising strategy for treating cerebral ischemia. This review briefly discusses the potential of ncRNAs as drug targets and explores the molecular regulatory mechanisms through which ncRNAs target astrocytes in cerebral ischemia. It provides an overview of the current research, discusses ncRNAs' implications as clinical markers for cerebral ischemia, and anticipates that ongoing research on ncRNAs may contribute to novel therapeutic approaches for treating this condition.

DEX Inhibits H/R-induced Cardiomyocyte Ferroptosis by the miR-141-3p/lncRNA TUG1 Axis

BACKGROUND

 Ferroptosis is emerging as a critical pathway in ischemia/reperfusion (I/R) injury, contributing to compromised cardiac function and predisposing individuals to sepsis and myocardial failure. The study investigates the underlying mechanism of dexmedetomidine (DEX) in hypoxia/reoxygenation (H/R)-induced ferroptosis in cardiomyocytes, aiming to identify novel targets for myocardial I/R injury treatment.

METHODS

 H9C2 cells were subjected to H/R and treated with varying concentrations of DEX. Additionally, H9C2 cells were transfected with miR-141-3p inhibitor followed by H/R treatment. Levels of miR-141-3p, long noncoding RNA (lncRNA) taurine upregulated 1 (TUG1), Fe2+, glutathione (GSH), and malondialdehyde were assessed. Reactive oxygen species (ROS) generation was measured via fluorescent labeling. Expression of ferroptosis-related proteins glutathione peroxidase 4 (GPX4) and acyl-CoA synthetase long-chain family member 4 (ACSL4) was determined using Western blot. The interaction between miR-141-3p and lncRNA TUG1 was evaluated through RNA pull-down assay and dual-luciferase reporter gene assays. The stability of lncRNA TUG1 was assessed using actinomycin D.

RESULTS

 DEX ameliorated H/R-induced cardiomyocyte injury and elevated miR-141-3p expression in cardiomyocytes. DEX treatment increased cell viability, Fe2+, and ROS levels while decreasing ACSL4 protein expression. Furthermore, DEX upregulated GSH and GPX4 protein levels. miR-141-3p targeted lncRNA TUG1, reducing its stability and overall expression. Inhibition of miR-141-3p or overexpression of lncRNA TUG1 partially reversed the inhibitory effect of DEX on H/R-induced ferroptosis in cardiomyocytes.

CONCLUSION

 DEX mitigated H/R-induced ferroptosis in cardiomyocytes by upregulating miR-141-3p expression and downregulating lncRNA TUG1 expression, unveiling a potential therapeutic strategy for myocardial I/R injury.

Non-coding RNAs and Aquaporin 4: Their Role in the Pathogenesis of Neurological Disorders

Neurological disorders are a major group of non-communicable diseases affecting quality of life. Non-Coding RNAs (ncRNAs) have an important role in the etiology of neurological disorders. In studies on the genesis of neurological diseases, aquaporin 4 (AQP4) expression and activity have both been linked to ncRNAs. The upregulation or downregulation of several ncRNAs leads to neurological disorder progression by targeting AQP4. The role of ncRNAs and AQP4 in neurological disorders is discussed in this review.

Novel Immune-Related LncRNA Pairs are Associated with Immunol Infiltration and Survival Status in Glioblastoma

Background

Immune-related lncRNA is involved in tumor initiation and progression, while its effect in glioblastoma (GBM) is still unknown.

Objective

We sought to investigate the association between immune-related lncRNA (ir-lncRNA) and GBM.

Methods

Transcriptomic and clinical data were obtained from the TCGA dataset, and we found 2008 ir-lncRNA differentially expressed between GBM and adjacent brain tissues.

Results

Appling the univariate Cox and Lasso regression model, we found 30 prognosis-related ir-lncRNA pairs to construct a Cox regression risk model to associate the outcome of GBM patients. Furthermore, with this risk model, we can identify the tumor immune infiltration status, the expression of immunosuppressive biomarkers, and chemical sensitivity in GBM patients.

Conclusions

We constructed an immunologic risk model with lncRNA to associate the survival outcome of GBM patients, which can provide useful biomarkers.

Butylphthalide improves brain damage induced by renal ischemia-reperfusion injury rats through Nrf2/HO-1 and NOD2/MAPK/NF-κB pathways

Renal ischemia-reperfusion (I/R) injury leads to irreversible brain damage with serious consequences. Activation of oxidative stress and release of inflammatory mediators are considered potential pathological mechanisms. Butylphthalide (NBP) has anti-inflammatory and antioxidant effects on I/R injuries. However, it is unclear whether NBP can effectively mitigate renal I/R secondary to brain injury as well as its mechanism, which are the aims of this study. Both renal I/R injury rats and oxygen and glucose deprivation cell models were established and pre-intervened NBP. The Morris water maze assay was used to detect behavior. Hippocampal histopathology and function were examined after renal I/R. Apoptosis and tube-forming capacity of brain microvascular endothelial cells (BMVECs) were tested. Immunohistochemistry and Western blot were used to measure protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1) pathway and NOD-like receptor C2 (NOD2)/Mitogen-activated protein kinases (MAPK)/Nuclear factor kappa-B (NF-κB) pathway. NBP treatment attenuated renal I/R-induced brain tissue damage and learning and memory dysfunction. NBP treatment inhibited apoptosis and promoted blood-brain barrier restoration and microangiogenesis. Also, it decreased oxidative stress levels and pro-inflammatory factor expression in renal I/R rats. Furthermore, NBP enhanced BMVECs' viability and tube-forming capacity while inhibiting apoptosis and oxidative stress. Notably, the alleviating effects of NBP were attributed to Nrf2/HO-1 pathway activation and NOD2/MAPK/NF-κB inhibition. This study demonstrates that NBP maintains BBB function by activating the Nrf2/HO-1 pathway and inhibiting the NOD2/MAPK/NF-κB pathway to suppress inflammation and oxidative stress, thereby alleviating renal I/R-induced brain injury.

Reduction of GAS5 and FOXD3-AS1 long non-coding RNAs in patients with bipolar disorder

Bipolar disorder (BD) patients suffer from severe disability and premature death because of failure in prognosis, diagnosis, and treatment. Although neural mechanisms of bipolar have not been fully discovered, studies have shown long noncoding RNAs (lncRNAs) can play an important role in signaling pathways such as PI3K/AKT pathway. There has been little study on deregulated lncRNAs and the lncRNAs' mode of action in the BD. Hence, we aimed to investigate the expression of PI3K/AKT pathway-related lncRNAs named TUG1, GAS5, and FOXD3-AS1 lncRNAs in the PMBC in 50 bipolar patients and 50 healthy controls. Our results showed that FOXD3-AS1 and GAS5 under-expressed significantly in bipolar patients compared to healthy controls (P = 0.0028 and P < 0.0001 respectively). Moreover, after adjustment, all P values remained significant (q value < 0.0001). According to the ROC curve, AUC (area under the curve), specificity, and sensitivity of these lncRNAs, GAS5 and FOXD3-AS1 might work as BD candidate diagnostic biomarkers. Taken together, the current results highlight that the dysregulation of FOXD3-AS1 and GAS5 may be associated with an increased risk of BD.

Involvement of NRON and TUG1 long noncoding RNAs in inflammation and the pathogenesis of EAE

There is growing evidence that the long noncoding RNAs (lncRNAs) contribute to the pathogenesis of various neurodegenerative diseases such as multiple sclerosis (MS). The role of lncRNAs nuclear repressor of NFAT (NRON) and Taurine up-regulated 1 (TUG1) in the inflammatory processes occurring in the experimental autoimmune encephalomyelitis (EAE) model of MS is yet to be investigated. Transcript levels of NRON and TUG1 in acute and chronic phases of EAE and cultured macrophages as well as the correlation between NRON and TUG1 expression with inflammatory cytokines, were evaluated in this study. EAE experimental model was induced in female C57BL/6 mice with subcutaneous injection of MOG35-55/CFA. Mice were scored for 28 days and then sacrificed. The expression of lncRNAs TUG1 and NRON in lumbar spinal cords, activated and controlled macrophages as well as the expression of IL-1, IL-6, and CDe-3 inflammatory cytokines, were assayed by real-time RT-PCR. The lncRNAs TUG1 and NRON were significantly down-regulated in lumbar spinal cords tissues in the acute phase of EAE compared to the control group. TUG1 and NRON were significantly down-regulated in macrophages treated with 10 ng lipopolysaccharide (LPS) compared to the control macrophages. A negative correlation was identified between NRON and TUG1 expression and IL-1, IL-6, and CDe-3 inflammatory cytokines. The present study demonstrates the dysregulation of lncRNAs TUG1 and NRON in spinal cord tissue lesions of EAE and activated macrophages, pointing to their potential role in the pathogenesis of EAE.

The Mechanism Underlying the Regulation of Long Non-coding RNA MEG3 in Cerebral Ischemic Stroke

Cerebral ischemic stroke is one of the leading causes of morbidity and mortality worldwide, and rapidly increasing annually with no more effective therapeutic measures. Thus, the novel diagnostic and prognostic biomarkers are urgent to be identified for prevention and therapy of ischemic stroke. Recently, long noncoding RNAs (lncRNAs), a major family of noncoding RNAs with more than 200 nucleotides, have been considered as new targets for modulating pathological process of ischemic stroke. In this review, we summarized that the lncRNA-maternally expressed gene 3 (MEG3) played a critical role in promotion of neuronal cell death and inhibition of angiogenesis in response to hypoxia or ischemia condition, and further described the challenge of overcrossing blood-brain barrier (BBB) and determination of optimal carrier for delivering lncRNA' drugs into the specific brain regions. In brief, MEG3 will be a potential diagnostic biomarker and drug target in treatment and therapy of ischemic stroke in the future.

LncRNA Taurine Up-Regulated 1 plays a proapoptotic role by regulating nuclear-cytoplasmic shuttle of HuR under the condition of neuronal ischemia

The study aimed to identify TUG1 as an essential regulator of apoptosis in HT22 (mouse hippocampal neuronal cells) by direct interaction with the RNA-binding protein HuR. In order to study the role of TUG1 in the context of ischemia, we used mouse hippocampal neuronal cells treated with oxyglucose deprivation to establish an in-vitro ischemia model. A bioinformatic analysis and formaldehyde RNA immunoprecipitation (fRIP) were used to investigate the biological functions. A Western blot assay and reverse transcription polymerase chain reaction were used to explore the expression of the molecules involved. A cell proliferation and cytotoxicity assay was performed to detect neuronal apoptosis. TUG1 exhibits a localization-specific expression pattern in HT22 cells under OGD treatment. The bioinformatics analysis showed a strong correlation between the TUG1 and HuR as predicted, and this interaction was subsequently confirmed by fRIP-qPCR. We found that HuR was translocated from the nucleus to the cytoplasm after ischemia treatment and subsequently targeted and stabilized COX-2 mRNA, which led to elevated COX-2 mRNA levels and apoptosis of the HT22 cells. Furthermore, nuclear-specific disruption of TUG1 prevented the translocation of HuR to the cytoplasm and decreased COX-2 mRNA expression, resulting in increased cell viability and partially reversed apoptosis. In conclusion, it was demonstrated that TUG1 accelerates the process of apoptosis by promoting the transfer of HuR to the cytoplasm and stabilizing COX-2 mRNA. These results provide useful information concerning a therapeutic target for ischemic stroke.

LncRNA TUG1 compromised neuronal mitophagy in cerebral ischemia/reperfusion injury by targeting sirtuin 1

BACKGROUND

Mitophagy protects against cerebral ischemia/reperfusion (CI/R)-induced neuronal apoptosis via mitochondrial clearance. Although taurine-upregulated gene 1 (lncRNA TUG1) has been proposed to be involved in the neuronal apoptosis evoked by CI/R, its specific role in mitophagy during the progression of CI/R injury remains unknown.

METHODS

The CI/R rat model was established using middle cerebral artery occlusion/reperfusion (MCAO/R). Human neuroblastoma cell line SH-SY5Y was subjected to oxygen-glucose deprivation and reoxygenation (OGD/R). Ubiquitination assay, co-immunoprecipitation assay, RNA pull-down, and RNA immunoprecipitation were used to determine the interplay among TUG1, sirtuin 1 (SIRT1), and F-box and WD repeat domain-containing 7 (FBXW7).

RESULTS

The upregulation of the TUG1 level and downregulation of the mitophagy were observed in both MCAO/R-treated rats and OGD/R-treated cells. The administration of si-TUG1 (a siRNA directed against TUG1) potentiated mitophagy and suppressed neuronal apoptosis in OGD/R-treated cells. However, the neuroprotective effect of si-TUG1 was reversed by mitophagy inhibitor or SIRT1 knockdown in vitro. Functionally, TUG1 enhanced FBXW7-mediated SIRT1 ubiquitination by upregulating FBXW7 expression. The overexpression of FBXW7 abrogated the si-TUG1-reinforced mitophagy by decreasing SIRT1 expression, thus aggravating neuronal apoptosis in the OGD/R+si-TUG1-treated cells. In rats with MCAO/R, the interference of TUG1 clearly decreased neuronal apoptosis, lessened the infarct volume, and relieved the neurological deficits.

CONCLUSION

TUG1 knockdown promotes SIRT1-induced mitophagy by suppressing FBXW7-mediated SIRT1 degradation, thus relieving the neuronal apoptosis induced by CI/R injury. LncRNA TUG1 promotes neuronal apoptosis through inhibition of mitophagy. TUG1 decreased SIRT1 expression by promoting FBXW7-mediated SIRT1 ubiquitination. FBXW7/SIRT1 axis mediated the effect of TUG1 on OGD/R-induced neuronal apoptosis by regulating mitophagy.

Taurine-Upregulated Gene 1 Attenuates Cerebral Angiogenesis following Ischemic Stroke in Rats

Objective

Angiogenesis is one of the therapeutic targets of cerebral infarction. Long noncoding RNAs (lncRNAs) can regulate the pathological process of angiogenesis following ischemic stroke. Taurine-upregulated gene 1 (TUG1), an lncRNA, is correlated to ischemic stroke. We intended to determine the effect of TUG1 on angiogenesis following an ischemic stroke.

Materials and Methods

Middle cerebral artery occlusion (MCAO) was adopted to build a focal ischemic model of the rat brain, and pcDNA-TUG1 and miR-26a mimics were injected into rats. Neurological function was estimated through modified neurological severity scores. The volume of focal brain infarction was calculated through 2,3,5-triphenyltetrazolium chloride staining. The level of TUG1 and miR-26a was measured by PCR. The expression of vascular endothelial growth factor (VEGF) and CD31 was checked using immunohistochemistry and western blot. The correlation between miR-26a and TUG1 was verified through a luciferase reporter assay.

Results

TUG1 increased noticeably while miR-26a was markedly reduced in MCAO rats. Overexpression of miR-26a improved neurological function recovery and enhanced cerebral angiogenesis in MCAO rats. TUG1 overexpression aggravated neurological deficits and suppressed cerebral angiogenesis in MCAO rats. Bioinformatics analysis revealed that miR-26a was one of the predicted targets of TUG1. Furthermore, TUG1 combined with miR-26a to regulate angiogenesis. TUG1 overexpression antagonized the role of miR-26a in neurological recovery and angiogenesis in MCAO rats.

Conclusions

TUG1/miR-26a, which may act as a regulatory axis in angiogenesis following ischemic stroke, can be considered a potential target for cerebral infarction therapy.

lncRNA WT1-AS attenuates hypoxia/ischemia-induced neuronal injury during cerebral ischemic stroke via miR-186-5p/XIAP axis

This study aimed to investigate the role and mechanism of long non-coding RNA (lncRNA) WT1 antisense RNA (WT1-AS) in cerebral ischemic stroke. The Starbase database and dual-luciferase reporter gene assay were used to analyze the interaction between lncRNA WT1 antisense RNA (lncRNA WT1-AS) and microRNA-186-5p (miR-186-5p). Reverse transcription-quantitative PCR analysis was performed to determine lncRNA WT1-AS and miR-186-5p levels. An oxygen glucose deprivation (OGD)-induced SH-SY5Y cell injury model was established. Cell viability and apoptosis were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and flow cytometric assays, respectively. Caspase 3 activity was evaluated using a caspase 3 activity detection kit. The results showed that miR-186-5p is a direct target of the lncRNA WT1-AS. In addition, lncRNA WT1-AS levels were downregulated and miR-186-5p levels were upregulated in the blood samples of patients with ischemic stroke and OGD-induced SH-SY5Y cells. WT1-AS overexpression promoted OGD-induced cell viability and reduced the cell apoptosis and caspase 3 activity. However, these effects were reversed by miR-186-5p overexpression. Furthermore, the results demonstrated that the X-linked inhibitor of apoptosis (XIAP) was directly targeted by miR-186-5p. Similarly, transfection with the miR-186-5p inhibitor reduced OGD-induced neuronal damage by upregulating XIAP expression. In conclusion, lncRNA WT1-AS attenuates hypoxia/ischemia-induced neuronal injury in cerebral ischemic stroke through the miR-186-5p/XIAP axis.

RP11-552D4.1: a novel m6a-related LncRNA associated with immune status in glioblastoma

Glioblastoma (GBM) is the most malignant form of brain cancer in the world. Nevertheless, the survival rate of patients with GBM is extremely low. N6-methyladenosine (m6A) and long noncoding RNAs (lncRNAs) conduct important biological functions in patients’ survival status and the immunotherapeutic response. Here, m6A-related lncRNAs were identified by a co-expression method. Univariate and multivariate Cox regression together with LASSO were applied to establish the risk model. Kaplan-Meier and ROC analysis were applied to evaluate the prediction power of this risk model. Finally, the related immune profiling and chemical sensitivity targets were also investigated. The risk model holding three m6A-related lncRNAs was confirmed as an independent predictor for the prognosis. Furthermore, we found the risk model based on m6A-related lncRNAs is associated with the immune status, immunosuppressive biomarkers, and chemo-sensitivity in GBM patients. The RP11-552D4.1 is found to facilitate neuronal proliferation. This risk model consisted of m6A-related lncRNAs may be available for the clinical interventions in GBM patients.

An update on the functional roles of long non‑coding RNAs in ischemic injury (Review)

Ischemic injuries result from ischemia and hypoxia in cells. Tissues and organs receive an insufficient supply of nutrients and accumulate metabolic waste, which leads to the development of inflammation, fibrosis and a series of other issues. Ischemic injuries in the brain, heart, kidneys, lungs and other organs can cause severe adverse effects. Acute renal ischemia induces acute renal failure, heart ischemia induces myocardial infarction and cerebral ischemia induces cerebrovascular accidents, leading to loss of movement, consciousness and possibly, life-threatening disabilities. Existing evidence suggests that long non-coding RNAs (lncRNAs) are regulatory sequences involved in transcription, post-transcription, epigenetic regulation and multiple physiological processes. lncRNAs have been shown to be differentially expressed following ischemic injury, with the severity of the ischemic injury being affected by the upregulation or downregulation of certain types of lncRNA. The present review article provides an extensive summary of the functional roles of lncRNAs in ischemic injury, with a focus on the brain, heart, kidneys and lungs. The present review mainly summarizes the functional roles of lncRNA MALAT1, lncRNA MEG3, lncRNA H19, lncRNA TUG1, lncRNA NEAT1, lncRNA AK139328 and lncRNA CAREL, among which lncRNA MALAT1, in particular, plays a crucial role in ischemic injury and is currently a hot research topic.

Long non-coding RNA lincRNA-erythroid prosurvival (EPS) alleviates cerebral ischemia/reperfusion injury by maintaining high-temperature requirement protein A1 (Htra1) stability through recruiting heterogeneous nuclear ribonucleoprotein L (HNRNPL)

This study aimed at investigating the role and mechanism of lincRNA-EPS (erythroid prosurvival) in cerebral ischemia/reperfusion (CIR) injury. The results showed that the overexpression of lincRNA-EPS was able to reduce the levels of interleukin-6, tumor necrosis factor-alpha and interleukin-1β stimulated in the OGD-treated Neuro-2a (N-2a) cells. The levels of reactive oxygen species and malondialdehyde were enhanced while the superoxide dismutase levels were reduced by oxygen and glucose deprivation (OGD) treatment, in which the lincRNA-EPS overexpression could reverse this effect in the cells. LincRNA-EPS interacted with high-temperature requirement protein A1 (Htra1) and heterogeneous nuclear ribonucleoprotein L (HNRNPL), and their depletion inhibited the Htra1 mRNA stability in N-2a cells. HNRNPL knockdown blocked lincRNA-EPS overexpression-induced Htra1 expression in the cells. The depletion of Htra1 could rescue lincRNA-EPS overexpression-mediated N-2a cell injury, inflammation, and oxidative stress induced by OGD. Functionally, lincRNA-EPS alleviates CIR injury of the middle cerebral artery occlusion/reperfusion mice in vivo. In conclusion, lincRNA-EPS attenuates CIR injury by maintaining Htra1 stability through recruiting HNRNPL.

Circular RNA PUM1 performs as a competing endogenous RNA of microRNA-340-5p to mediate DEAD-box helicase 5 to mitigate cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion damages local brain tissue and impairs brain function, but its specific pathogenesis is still uncertain. Recent studies have clarified circPUM1 is aberrantly elevated in cerebral ischemia-reperfusion injury; however, circPUM1ʹs function in cerebral ischemia-reperfusion-induced neuronal injury remains ambiguous. The results illustrated circPUM1 and DEAD-box helicase 5 were decreased, but microRNA-340-5p was elevated in transient middle cerebral artery occlusion mice and oxygen glucose deprivation/reoxygenation-treated SH-SY5Y cells. Knockdown of circPUM1 aggravated the neuronal injury in transient middle cerebral artery occlusion mice and motivated glial cell activation, neuronal apoptosis and inflammation. Enhancing circPUM1 restrained oxygen glucose deprivation/reoxygenation-induced SH-SY5Y cell apoptosis, the release of lactate dehydrogenase and inflammatory factors, and activation of nuclear factor-kappaB pathway, while elevating microRNA-340-5p aggravated oxygen glucose deprivation/reoxygenation-induced cell damage. Functional rescue experiments exhibited that the impacts of knockdown or enhancement of circPUM1 were turned around by microRNA-340-5p downregulation and DEAD-box helicase 5 silencing, respectively. Moreover, it was demonstrated that circPUM1 competitively adsorbed microRNA-340-5p to mediate DEAD-box helicase 5. All in all, this study clarifies that circPUM1 mitigates cerebral ischemia-reperfusion-induced neuronal injury by targeting the microRNA-340-5p/DEAD-box helicase 5 axis.

LncRNA TUG1 Promotes Apoptosis, Invasion, and Angiogenesis of Retinal Endothelial Cells in Retinopathy of Prematurity via MiR-145-5p

Purpose

Retinopathy of prematurity (ROP) is a common retinal vascular disease in premature neonates. In recent years, there is increasing evidence that the long non-coding RNA taurine upregulated gene 1 (TUG1) plays a regulatory role in vascular diseases, suggesting a potential role for TUG1 in vascular endothelial cells. We hypothesized that TUG1 may be associated with ROP. Our aim, therefore, was to explore the biological functions of TUG1 in aberrant retinal development.

Methods

We used the mouse oxygen-induced retinopathy (OIR) model to simulate the pathological changes of retinal in ROP. Quantitative real-time polymerase chain reaction was used to detect the expression of TUG1, miR-145-5p and cellular communication network factor 1 (CCN1). Human retinal endothelial cells (HRECs) were treated with CoCl₂ to mimic hypoxia conditions. Cellular functional changes were observed after transfection with RNA interference (RNAi)-TUG1 and miR-145-5p mimics. The apoptosis of HRECs was detected by flow cytometry, the migration ability was detected by wound healing and transwell migration assays, and the ability of angiogenesis was detected by tube formation assay. The potential binding sites between TUG1, miR-145-5p, and CCN1 were verified by dual-luciferase reporter assays. The degree of retinopathy was evaluated by staining retinal sections with hematoxylin and eosin, and the expression of CCN1, HIF-1α, VEGF, caspase-3, Bcl-2, IL-1β, and TNF-α protein was analyzed by Western blotting and immunohistochemistry.

Results

In the retina tissue of OIR mice, TUG1, miR-145-5p, and CCN1 were differentially expressed. Knocking down TUG1 attenuated apoptosis, migration, and angiogenesis induced by hypoxia on HRECs, as did miR-145-5p overexpression. Results from reporter assays indicate direct interactions between TUG1, miR-145-5p, and CCN1. Intravitreal injection of miR-145-5p mimics reduced the degree of retinopathy.

Conclusion

TUG1 acts as a molecular sponge of miR-145-5p to regulate CCN1 expression and thus regulate the development of retinal neovascularization. This regulatory mechanism may provide a new theoretical basis for the prevention and treatment of ROP.

CircRNA CTNNB1 (circCTNNB1) ameliorates cerebral ischemia/reperfusion injury by sponging miR-96-5p to up-regulate scavenger receptor class B type 1 (SRB1) expression

Emerging studies show that circRNA catenin beta 1 (circCTNNB1) plays a critical role in cancer. However, the expression and function of circCTNNB1 in cerebral ischemia/reperfusion injury (IRI) have not been reported. The present study discovered that circCTNNB1 and scavenger receptor class B type 1 (SRB1) expression levels were significantly down-regulated in mouse astrocytes (mAS) treated with oxygen glucose deprivation and reperfusion (OGD/R), and similar results were observed in a mouse middle cerebral artery occlusion model. Overexpression of circCTNNB1 alleviated cell apoptosis, oxidative stress and the inflammatory response induced by OGD/R in vitro. Up-regulation of circCTNNB1 increased SRB1 expression levels to protect mAS cells from OGD/R-induced damage. CircCTNNB1 and SRB1 interacted with miR-96-5p, and the overexpression of miR-96-5p efficiently reversed the function of circCTNNB1 in OGD/R-treated mAS cells. CircCTNNB1 protected against cerebral ischemia-reperfusion injury by up-regulating SRB1 in vivo. In conclusion, our findings suggest that circCTNNB1 acts as a competitive endogenous RNA for miR-96-5p to alleviate cerebral IRI, which provides novel evidence that circCTNNB1 and SRB1 may be biomarkers and therapeutic targets for cerebral IRI.

LncRNA TUG1 functions as a ceRNA for miR-1-3p to promote cell proliferation in hepatic carcinogenesis

Background

Hepatocellular carcinoma (HCC) is characterised by high malignancy, metastasis and recurrence, but the specific mechanism that drives these outcomes is unclear. Recent studies have shown that long noncoding RNAs (lncRNAs) can regulate the proliferation and apoptosis of hepatic cells.

Methods

We searched for lncRNAs and microRNAs (miRNAs), which can regulate IGF1 expression, through a bioinformatics website, and predicted that lncRNA taurine‐upregulated gene 1 (TUG1) would have multiple targets for miR‐1‐3p binding, meaning that lncRNA TUG1 played an adsorption role. A double luciferase assay was used to verify the targeting relationship between lncRNA TUG1 and miR‐1‐3p. Western blotting and qPCR were used to verify the targeting relationship between miR‐1‐3p and IGF1, and qPCR was used to verify the regulatory relationship between the lncRNA TUG1‐miR‐1‐3p‐IGF1 axis. CCK‐8 was used to detect the growth activity of miRNA‐transfected L‐O2 cells, and flow cytometry was used to detect cell cycle changes and apoptosis.

Result

The proliferation cycle of L‐O2 cells transfected with miR‐1‐3p mimics was significantly slowed. Flow cytometry showed that the proliferation of L‐O2 cells was slowed, and the apoptosis rate was increased. In contrast, when L‐O2 cells were transfected with miR‐1‐3p inhibitor, the expression of IGF1 was significantly upregulated, and the cell proliferation cycle was significantly accelerated. Flow cytometry showed that the cell proliferation rate was accelerated, and the apoptosis rate was reduced.

Conclusion

LncRNA TUG1 can adsorb miR‐1‐3p as a competitive endogenous RNA (ceRNA) to promote the expression of IGF1 and promote cell proliferation in hepatic carcinogenesis.

YY1-induced long non-coding RNA small nucleolar RNA host gene 8 promotes the tumorigenesis of melanoma via the microRNA-656-3p/SERPINE1 mRNA binding protein 1 axis

Long non-coding (lnc) RNA serves a vital role in the cellular processes of carcinoma. This study aimed to explore the accurate mechanism underlying lncRNA small nucleolar RNA host gene 8 (SNHG8) in melanoma. In this study, lncRNA SNHG8 expression were upregulated in melanoma tissues and cells, and lncRNA SNHG8 knockdown reduced melanoma cell viability, migration and invasion. Moreover, lncRNA SNHG8 expression could be induced by transcription factor YY1. In addition, we found that miR-656 could directly bind to lncRNA SNHG8 and SERPINE1 mRNA binding protein 1 (SERBP1). Rescue assays indicated that miR-656 overexpression inhibited the aforementioned cellular activities in melanoma cells, which were reversed by SERBP1 overexpression. In conclusion, this work elucidated that YY1-induced upregulation of lncRNA SNHG8 boosted the development of melanoma via the miR-656-3p/SERBP1 axis, providing a novel therapeutic strategy for melanoma treatment.

The Long-Noncoding RNA TUG1 Regulates Oxygen-Induced Retinal Neovascularization in Mice via MiR-299

Purpose

The oxygen-induced retinal neovascularization mouse model closely approximates pathological changes associated with human retinal neovascularization-associated diseases, including retinopathies. We used this model and human retinal endothelial cells (HRECs) under hypoxia to explore the relationship between taurine upregulated gene-1 (TUG1), vascular endothelial growth factor (VEGF), and miR-299-3p on retinopathy of prematurity (ROP).

Methods

An oxygen-induced retinopathy (OIR) mouse model was established; the mice were divided into a normal control group, OIR group, TUG1 control group (lentivirus control), and TUG1-knockdown group. The apoptosis of retinal cells was evaluated using a TUNEL assay. Angiogenic, apoptotic, and inflammatory factors were detected by Western blot, immunohistochemistry, and immunofluorescence analyses. HRECs were cultured under hypoxia and assessed for VEGF expression, apoptosis, tubule formation, and migration ability. The relationship between TUG1, VEGF, and miR-299-3p was detected via a dual luciferase reporter gene assay.

Results

Intravitreal injection of TUG1 lentivirus reduced the inflammatory response in the mouse retinal tissue and markedly reduced pathological changes in the retina. Overexpression of miR-299 in HRECs reduced the apoptosis rate, tube formation, and migration ability of hypoxia-treated cells, thereby inhibiting the formation of new blood vessels. The dual luciferase reporter gene assay suggested that miR-299 has binding sites for TUG1 and VEGF.

Conclusions

TUG1 reduces the expression of VEGFA by competitively adsorbing miR-299-3p and facilitates the regulation of retinal neovascularization, suggesting that it may serve as a new therapeutic target for retinal neovascular diseases.

Long Non-Coding RNA-Mediated Competing Endogenous RNA Networks in Ischemic Stroke: Molecular Mechanisms, Therapeutic Implications, and Challenges

Ischemic stroke (IS) is a disease that is characterized by high mortality and disability. Recent studies have shown that LncRNA-mediated competing endogenous RNA (ceRNA) networks play roles in the occurrence and development of cerebral I/R injury by regulating different signaling pathways. However, no systematic analysis of ceRNA mechanisms in IS has been reported. In this review, we discuss molecular mechanisms of LncRNA-mediated ceRNA networks under I/R injury. The expression levels of LncRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) and their effects in four major cell types of the neurovascular unit (NVU) are also involved. We further summarize studies of LncRNAs as biomarkers and therapeutic targets. Finally, we analyze the advantages and limitations of using LncRNAs as therapeutics for IS.

Silencing of H19 alleviates oxygen-glucose deprivation/reoxygenation-triggered injury through the regulation of the miR-1306-5p/BCL2L13 axis

Cerebral ischemia/reperfusion (I/R) injury remains a leading cause of death and disability. Long noncoding RNAs (lncRNAs) exert key functions in cerebral I/R injury. Here, we sought to elucidate the mechanism underlying the regulation of H19 in cerebral I/R cell injury. An in vitro model of cerebral I/R injury was created using oxygen-glucose deprivation/reoxygenation (OGD/R). The levels of H19, miR-1306-5p and B cell lymphoma-2 (Bcl-2)-like 13 (BCL2L13) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell viability and apoptosis were determined by the Cell Counting-8 Kit (CCK-8) assay and flow cytometry, respectively. The levels of lactate dehydrogenase (LDH) and cytokines were evaluated by enzyme-linked immunosorbent assays (ELISA). Direct relationships among H19, miR-1306-5p and BCL2L13 were verified by dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pulldown assays. Our data showed that H19 and BCL2L13 were highly expressed in the cerebral I/R injury rats and OGD/R-triggered SK-N-SH and IMR-32 cells. The knockdown of H19 or BLC2L13 alleviated OGD/R-triggered injury in SK-N-SH and IMR-32 cells. Moreover, H19 silencing protected against OGD/R-triggered cell injury by down-regulating BCL2L13. H19 acted as a sponge of miR-1306-5p and BCL2L13 was a direct target of miR-1306-5p. H19 mediated BCL2L13 expression by sequestering miR-1306-5p. Furthermore, miR-1306-5p was a molecular mediator of H19 function. These results suggested that H19 silencing alleviated OGD/R-triggered I/R injury at least partially depending on the regulation of the miR-1306-5p/BCL2L13 axis.

Long non-coding RNA LOC366613 alleviates the cerebral ischemic injury via regulating the miR-532-5p/phosphatase and tensin homolog axis

Cerebral infarction (CI) has become a leading cause of death in China. Long non-coding RNAs (lncRNAs) are intensively involved in the progression of CI. Here, we aimed to investigate the effects of lncRNA LOC366613 (LOC366613) on cerebral I/R injury, as well as its possible mechanism. Transient middle cerebral artery occlusion (MCAO) was used to establish a mouse model of cerebral I/R, and the PC12 cell line was used to establish an in vitro oxygen-glucose deprivation (OGD) injury model. The MTT assay was used to determine cell viability, and qRT-PCR was used to determine RNA levels. Western blotting was conducted to detect protein expression levels. The TUNEL assay and flow cytometry were used to measure cell apoptosis, and 2,3,5-triphenyltetrazolium chloride (TTC) was used to determine cerebral infarct volume. Finally, RNA pull-down and luciferase activity assays were used to examine interactions between miR-532-5p and LOC366613, as well as between miR-532-5p and phosphatase and tensin homolog (PTEN). LOC366613 was overexpressed in patients with cerebral I/R injury. In PC12 cells, knockdown of LOC366613 reduced the apoptosis rate and lactic acid dehydrogenase (LDH) expression, while increasing cell viability. Moreover, miR-532-5p was shown to be a target of LOC366613, as predicted. Downregulation of miR-532-5p reversed the effects of LOC366613 knockdown on PC12 cell apoptosis, LDH release, and cell viability. Finally, PTEN was verified as a target of miR-532-5p. LOC366613 participates in cerebral I/R injury by regulating the miR-532-5p/PTEN axis, potentially providing a new CI treatment target.

Interfering TUG1 Attenuates Cerebrovascular Endothelial Apoptosis and Inflammatory injury After Cerebral Ischemia/Reperfusion via TUG1/miR-410/FOXO3 ceRNA Axis

Background Emerging studies illustrate that long non-coding RNA TUG1 (TUG1) participates in neuron death after ischemia. However, the role of TUG1 in cerebral ischemia/reperfusion (CI/R) injury through cerebrovascular pathology was undetermined yet. Methods Expression of TUG1, miRNA-410-3p (miR-410), and forkhead box O3 (FOXO3) was detected by RT-qPCR and western blot. Neural function, apoptosis, and inflammatory damage were assessed by triphenyltetrazolium chloride straining, modified neurological severity score, fluorescence-activated cell sorting method, and western blot. The relationship among TUG1, miR-410, and FOXO3 was identified by dual-luciferase reporter assay, RNA pull-down, and RNA immunoprecipitation. Results TUG1 was upregulated in middle cerebral artery occlusion/reperfusion (MCAO/R) mice and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced mouse brain microvascular endothelial cells (BMECs) in a certain of time-dependent manner. Blockage of TUG1 decreased infarct volume and increased neurological score in MCAO/R mice, accompanied with elevated Bcl-2 expression and declined expression of IL-1β, IL-6, TNF-α, Bax, and cleaved caspase 3. Abovementioned proteins were similarly expressed in OGD/R-induced BMECs with TUG1 knockdown, paralleled with diminished apoptosis rate. Either, miR-410 overexpression and FOXO3 interference could suppress OGD/R-induced inflammatory and apoptotic responses. Of note, TUG1 and FOXO3 are competing endogenous RNAs (ceRNAs) for miR-410 via target binding. Depleting miR-410 counteracted the role of TUG1 exhaustion, and reinforcing FOXO3 abated the effect of miR-410 overexpression. Conclusion Exhausting TUG1 could alleviate CI/R-induced inflammatory injury and apoptosis in brain tissues and BMECs via targeting miR-410/FOXO3 axis, suggesting an innovative perspective from cerebrovascular endothelial cells in the pathogenesis and treatment of CI/R.

Epigenetic Regulations of Microglia/Macrophage Polarization in Ischemic Stroke

Ischemic stroke is one of the leading causes of death and disability worldwide. Microglia/macrophages (MMs)-mediated neuroinflammation contributes significantly to the pathological process of ischemic brain injury. Microglia, serving as resident innate immune cells in the central nervous system, undergo pro-inflammatory phenotype or anti-inflammatory phenotype in response to the microenvironmental changes after cerebral ischemia. Emerging evidence suggests that epigenetics modifications, reversible modifications of the phenotype without changing the DNA sequence, could play a pivotal role in regulation of MM polarization. However, the knowledge of the mechanism of epigenetic regulations of MM polarization after cerebral ischemia is still limited. In this review, we present the recent advances in the mechanisms of epigenetics involved in regulating MM polarization, including histone modification, non-coding RNA, and DNA methylation. In addition, we discuss the potential of epigenetic-mediated MM polarization as diagnostic and therapeutic targets for ischemic stroke. It is valuable to identify the underlying mechanisms between epigenetics and MM polarization, which may provide a promising treatment strategy for neuronal damage after cerebral ischemia.

LncRNA TUG1 attenuates ischaemia-reperfusion-induced apoptosis of renal tubular epithelial cells by sponging miR-144-3p via targeting Nrf2

Renal ischaemia/reperfusion (I/R) injury may induce kidney damage and dysfunction, in which oxidative stress and apoptosis play important roles. Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are reported to be closely related to renal I/R, but the specific molecular mechanism is still unclear. The purpose of this research was to explore the regulatory effect of lncRNA TUG1 on oxidative stress and apoptosis in renal I/R injury. This research revealed that in renal I/R injury and hypoxia/reperfusion (H/R) injury in vitro, the expression level of lncRNA TUG1 was upregulated, and oxidative stress levels and apoptosis levels were negatively correlated with the expression level of lncRNA TUG1. Using bioinformatics databases such as TargetScan and microRNA.org, microRNA-144-3p (miR-144-3p) was predicted to be involved in the association between lncRNA TUG1 and Nrf2. This study confirmed that the level of miR-144-3p was significantly reduced following renal I/R injury and H/R injury in vitro, and miR-144-3p was determined to target Nrf2 and inhibit its expression. In addition, lncRNA TUG1 can reduce the inhibitory effect of miR-144-3p on Nrf2 by sponging miR-144-3p. In summary, our research shows that lncRNA TUG1 regulates oxidative stress and apoptosis during renal I/R injury through the miR-144-3p/Nrf2 axis, which may be a new treatment target for renal I/R injury.

Noncoding RNA crosstalk in brain health and diseases

The mammalian brain expresses several classes of noncoding RNAs (ncRNAs), including long ncRNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs). These ncRNAs play vital roles in regulating cellular processes by RNA/protein scaffolding, sponging and epigenetic modifications during the pathophysiological conditions, thereby controlling transcription and translation. Some of these functions are the result of crosstalk between ncRNAs to form a competitive endogenous RNA network. These intricately organized networks comprise lncRNA/miRNA, circRNA/miRNA, or lncRNA/miRNA/circRNA, leading to crosstalk between coding and ncRNAs through miRNAs. The miRNA response elements predominantly mediate the ncRNA crosstalk to buffer the miRNAs and thereby fine-tune and counterbalance the genomic changes and regulate neuronal plasticity, synaptogenesis and neuronal differentiation. The perturbed levels and interactions of the ncRNAs could lead to pathologic events like apoptosis and inflammation. Although the regulatory landscape of the ncRNA crosstalk is still evolving, some well-known examples such as lncRNA Malat1 sponging miR-145, circRNA CDR1as sponging miR-7, and lncRNA Cyrano and the circRNA CDR1as regulating miR-7, has been shown to affect brain function. The ability to manipulate these networks is crucial in determining the functional outcome of central nervous system (CNS) pathologies. The focus of this review is to highlights the interactions and crosstalk of these networks in regulating pathophysiologic CNS function.

Long non-coding RNA TUG1 knockdown prevents neurons from death to alleviate acute spinal cord injury via the microRNA-338/BIK axis

Taurine up-regulated gene 1 (TUG1) is a cancer-associated long noncoding RNA (lncRNA) and engages in the development of spinal cord injury (SCI), a suffering neuropathological disorder. However, the regulatory role of TUG1 in acute SCI (ASCI) is still underdetermined. RT-qPCR and western blot analysis were applied to measure the expression of TUG1, microRNA-338 (miR-338), Bcl2-interacting killer (BIK), cleaved caspase 3 (c-caspase 3) and hypoxia-inducible factor-1 alpha (HIF-1α) in ASCI rats and hypoxic cells. Cell death was evaluated using flow cytometric analysis. The relationships among miR-338, TUG1 or BIK were confirmed by luciferase reporter assay, RNA immunoprecipitation and RNA pull-down. Accordingly, we monitored higher expression of TUG1 and BIK, but lower expression of miR-338 in ASCI rats and hypoxic cells. In vitro, hypoxia expedited cell death and c-caspase 3 levels. In vivo, ASCI rats were successfully developed as evidenced by diminished Basso-Beattie-Bresnahan (BBB) locomotor score and enhanced c-caspase 3 and HIF-1α expression. Nevertheless, TUG1 knockdown mitigated the cell death in ASCI rats and hypoxic cells. Mechanically, TUG1 interacted with miR-338 to regulate the BIK expression. Together, TUG1 silencing could alleviate the death in neurons and ASCI models via modulating the miR-338/BIK axis.

Knockdown of lncRNA TUG1 attenuates cerebral ischemia/reperfusion injury through regulating miR-142-3p

Cerebral ischemia-reperfusion injury (CI/RI) is one of the most common diseases of the central nervous system. At present, there is no specific treatment for CI/RI. It is necessary to explore the mechanism of CI/RI and find new ways to prevent and treat CI/RI. An oxygen and glucose deprivation/recovery (OGD/R) model was established to evaluate the effects of mouse astrocytes (MA-C) cell viability and apoptosis of stepwise exposure to oxygen and glucose deprivation followed by their replenishment. This assessment included using taurine upregulated gene 1-small interfering RNAs (TUG1-siRNA) transfection to determine the effects of TUG1 knockdown on MA-C survival and apoptosis. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to evaluate TUG1 and miR-142-3p expression levels. The luciferase gene reporter assay was performed to validate that miR-142-3p is a TUG1 target. Accordingly, the effects of miR-142-3p knockdown on TUG1-induced MA-C apoptosis were determined using flow cytometry. Methyl thiazolyl tetrazolium (MTT) method was used to detect cell growth viability. Western blotting analysis was performed to detect the expression levels of apoptosis-related proteins. TUG1 was upregulated, while miR-142-3p was downregulated in the OGD/R model of MA-C cells. Inhibiting the expression of TUG1 could protect MA-C cells and reverse the decrease in growth viability and increasing apoptosis of MA-C cells caused by OGD/R stimulation. On the other hand, the inhibition of miR-142-3p offset the effect of TUG1 knockdown on cell viability and apoptosis. Inhibition of OGD/R-induced increases in TUG1 expression that in turn reduces miR-142-3p upregulation may suppress reperfusion-induced losses in cell viability.

Long non-coding RNA TUG1 knockdown promotes autophagy and improves acute renal injury in ischemia-reperfusion-treated rats by binding to microRNA-29 to silence PTEN

Objective

Long noncoding RNA (lncRNA) taurine upregulated gene 1 (TUG1) is increased under the condition of ischemia. This study intended to identify the mechanism of TUG1 in renal ischemia-reperfusion (I/R).

Methods

First, a rat model of acute renal injury induced by I/R was established, followed by the measurement of blood urea nitrogen (BUN), serum creatine (SCr), methylenedioxyphetamine (MDA) and superoxide dismutase (SOD) in the serum of rats. TUG1 was knocked down in I/R rats (ko-TUG1 group). Next, histological staining was used to evaluate the pathological damage and apoptosis of rat kidney. Western blot analysis was used to detect the levels of apoptosis- and autophagy-related proteins and transmission electron microscope was used to observe autophagosomes. Autophagy and apoptosis were evaluated after inhibition of the autophagy pathway using the inhibitor 3-MA. The targeting relation among TUG1, microRNA (miR)-29 and phosphatase and tensin homolog (PTEN) were validated. Lastly, the effects of TUG1 on biological behaviors of renal tubular cells were evaluated in vitro.

Results

In vivo, the levels of BUN, SCr and MDA in the serum of I/R-treated rats were increased while SOD level and autophagosomes were reduced, tubule epithelial cells were necrotic, and TUG1 was upregulated in renal tissues of I/R-treated rats, which were all reversed in rats in the ko-TUG1 group. Autophagy inhibition (ko-TUG1 + 3-MA group) averted the protective effect of TUG1 knockdown on I/R-treated rats. TUG1 could competitively bind to miR-29 to promote PTEN expression. In vitro, silencing TUG1 (sh-TUG1 group) promoted viability and autophagy of renal tubular cells and inhibited apoptosis.

Conclusions

LncRNA TUG can promote PTEN expression by competitively binding to miR-29 to promote autophagy and inhibited apoptosis, thus aggravating acute renal injury in I/R-treated rats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02473-0.

Long non‑coding RNA XIST promotes cerebral ischemia/reperfusion injury by modulating miR‑27a‑3p/FOXO3 signaling

Cerebral ischemia/reperfusion (I/R) injury leads to neuronal damage, which may cause disability and even mortality. Multiple studies have revealed that long non‑coding RNAs (lncRNAs) serve pivotal roles in the pathogenesis of cerebral I/R injury. Therefore, the present study aimed to investigate whether the lncRNA X inactivate‑specific transcript (XIST) protects neuronal cells from cerebral I/R injury. In the present study, reverse transcription‑quantitative PCR demonstrated that XIST expression was upregulated in the brain tissues of an I/R mouse model and in oxygen and glucose deprivation/reperfusion (OGD/R)‑treated Neuro‑2a (N2a) cells. Knockdown of XIST alleviated cerebral injury, as well as reduced N2a cell apoptosis and reactive oxygen species (ROS) production. Additionally, luciferase reporter and RNA immunoprecipitation assays identified that XIST could bind with microRNA (miR)‑27a‑3p. It was found that miR‑27a‑3p expression was downregulated in the brain tissues of an I/R mouse model and in OGD/R‑induced N2a cells. In addition, miR‑27a‑3p overexpression attenuated I/R‑induced cerebral injury, and inhibited the apoptosis and ROS production of N2a cells. miR‑27a‑3p was found to target FOXO3. Silencing of FOXO3 alleviated cerebral injury, as well as inhibited N2a cell apoptosis and ROS production. Collectively, these findings indicated that XIST aggravated cerebral I/R injury by regulating miR‑27a‑3p/FOXO3 signaling, which may provide a novel insight into the treatment of cerebral I/R injury.

Long non-coding RNA TUG1 aggravates cerebral ischemia and reperfusion injury by sponging miR-493-3p/miR-410-3p

Background

Cerebral ischemia and reperfusion injury (CIRI) affects bodily function by causing irreversible damage to brain cells. The diverse pathophysiological course factors hinder the research work to go deeper. Long noncoding RNA taurine-upregulated gene 1 (TUG1) has been reported to be related to CIRI. This study explored the undefined regulatory pathway of TUG1 in CIRI.

Methods

Quantitative real-time polymerase chain reaction was applied to test the expression of TUG1, microRNA (miR)-493-3p and miR-410-3p. The viability and apoptosis of oxygen and glucose deprivation/reoxygen (OGD/R) model cells were evaluated by cell counting kit-8 and flow cytometry assay, respectively. The determination of inflammatory factors of interleukin-6, interleukin-1β and tumor necrosis factor-α was presented by enzyme-linked immunosorbent assay. The oxidative stress was performed by measuring the generation of malondialdehyde, reactive oxygen species and the activity of superoxide dismutase. Cytotoxicity was presented by measuring the generation of lactate dehydrogenase. Western blot assay was devoted to assessing the level of apoptosis-related factors (cleaved-caspase-3 and cleaved-caspase-9) and the protein level of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) pathway-related factors in neuro-2a cells treated by OGD/R. Besides, online database starBase was applied to predict the potential binding sites of TUG1 to miR-493-3p and miR-410-3p, which was further confirmed by the dual-luciferase reporter system.

Results

The expression of TUG1 was upregulated, while miR-493-3p or miR-410-3p was downregulated in the serum of CIRI and OGD/R model cells. Meanwhile, knockdown of TUG1 eliminated the suppression in proliferation, the promotion in apoptosis, inflammation and oxidative stress, as well as the cytotoxicity in OGD/R model cells. Interestingly, the inhibition of miR-493-3p or miR-410-3p allayed the above effects. In addition, TUG1 harbored miR-493-3p or miR-410-3p and negatively regulated their expression. Finally, the TUG1 activated JNK and p38 MAPK pathways by sponging miR-493-3p/miR-410-3p.

Conclusion

TUG1 motivated the development of CIRI by sponging miR-493-3p/miR-410-3p to activate JNK and p38 pathways. The novel role of TUG1 in CIRI may contribute to the advancement of CIRI treatment.

LncRNA TUG1 Demethylated by TET2 Promotes NLRP3 Expression, Contributes to Cerebral Ischemia/Reperfusion Inflammatory Injury

LncRNA TUG1 has not yet been reported in cerebral ischemia/reperfusion (I/R) injury. Methylcytosine dioxygenase TET2 is involved in ischemic damage. This study aimed to investigate the effects of TUG1 demethylated by TET2 on I/R-induced inflammatory response and identified its possible mechanisms.We found that TUG1 expression was significantly upregulated in oxygen-glucose deprivation and reoxygenation (OGD/R)-induced SH-SY5Y and SK-N-SH cells. Using the middle cerebral artery occlusion (MCAO) mice, we observed a similar effect. We also found that I/R injury could downregulate miR-200a-3p and upregulate NLRP3 and TET2. The knockdown of TUG1 could alleviate OGD/R-induced inflammatory response through upregulating miR-200a-3p and downregulating NLRP3 and other pro-inflammatory molecules. miR-200a-3p inhibition can partially reverse the effects of TUG1 silencing. Further experiments confirmed that TUG1 sponged miR-200a-3p to diminish miR-200a-3p and promote NLRP3 dependent inflammatory responses. Mechanically, knockdown of TET2 induced low levels of TUG1 and high levels of miR-200a-3p in both SK-N-SH and SH-SY5Y cells. IL-18, IL-1β, NLRP3, Caspase-1, and GSDMD-N were highly downregulated in OGD/R-induced SK-N-SH and SH-SY5Y cells after TET2 knockdown. TUG1 overexpression could reverse this effect. All the data indicated that TET2 could demethylate TUG1 and contribute to the inflammatory response. In additional experiments using the MCAO mice model, we confirmed knockdown of TET2 attenuated I/R-induced inflammatory response and brain injuries via decreasing TUG1 and increasing miR-200a-3p to inhibit NLRP3 expression. The demethylation of TUG1 by TET2 might aggravate I/R-induced inflammatory injury via modulating NLRP3 by miR-200a-3p. Our data confirmed that TET2 contributed to I/R-induced inflammatory response via the demethylation of TUG1 and regulated TUG1/miR-200a-3p/NLRP3 pathway.

Inhibition of Long Noncoding RNA SNHG15 Ameliorates Hypoxia/Ischemia-Induced Neuronal Damage by Regulating miR-302a-3p/STAT1/NF-κB Axis

PURPOSE

Ischemic brain injury results in high mortality and serious neurologic morbidity. Here, we explored the role of SNHG15 in modulating neuronal damage and microglial inflammation after ischemia stroke.

MATERIALS AND METHODS

The hypoxia/ischemia models were induced by middle cerebral artery occlusion in mice and oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro. Quantitative real-time PCR (qRT-PCR) and Western blot were conducted to determine the levels of SNHG15, miR-302a-3p, and STAT1/NF-κB. Moreover, gain- or loss-of functional assays of SNHG15 and miR-302a-3p were conducted. MTT assay was used to evaluate the viability of HT22 cells, and the apoptotic level was determined by flow cytometry. Furthermore, enzyme-linked immunosorbent assay was performed to detect oxidative stress and inflammatory mediators in the ischemia cortex and OGD/R-treated BV2 microglia.

RESULTS

The SNHG15 and STAT1/NF-κB pathways were both distinctly up-regulated, while miR-302a-3p was notably down-regulated in the ischemia cortex. Additionally, overexpressing SNHG15 dramatically enhanced OGD/R-mediated neuronal apoptosis as well as the expression of oxidative stress and inflammation factors from microglia. In contrast, knocking down SNHG15 or overexpressing miR-302a-3p relieved OGD/R-mediated neuronal apoptosis and microglial activation. Moreover, the rescue experiment testified that overexpressing miR-302a-3p also attenuated SNHG15 up-regulation-induced effects. In terms of the mechanisms, SNHG15 sponged miR-302a-3p and activated STAT1/NF-κB as a competitive endogenous RNA, while miR-302a-3p targeted STAT1 and negatively regulated the STAT1/NF-κB pathway.

CONCLUSION

SNHG15 was up-regulated in the hypoxia/ischemia mouse or cell model. The inhibition of SNHG15 ameliorates ischemia/hypoxia-induced neuronal damage and microglial inflammation by regulating the miR-302a-3p/STAT1/NF-κB pathway.

LncRNA SNHG15 Knockdown Protects Against OGD/R-Induced Neuron Injury by Downregulating TP53INP1 Expression via Binding to miR-455-3p

Cerebral ischemia-reperfusion (I/R) injury is the common symptom of ischemic stroke, which poses a heavy burden to human health. Long non-coding RNA (lncRNA) is indicated to be a critical regulator in cerebral ischemia. This study aims to reveal the effects of lncRNA small nucleolar RNA host gene 15 (SNHG15) on oxygen-glucose deprivation and reoxygenation (OGD/R)-induced neuron injury and underlying mechanism. The expression levels of SNHG15, microRNA-455-3p (miR-455-3p) and tumour protein p53 inducible nuclear protein 1 (TP53INP1) mRNA were determined by quantitative real time polymerase chain reaction in P12 cells. The protein levels of TP53INP1, cleaved caspase-3, caspase-3, B-cell lymphoma-2 and BCL2-associated x protein (Bax) were detected by western blot in P12 cells. Cell viability and apoptosis were revealed by cell counting kit-8 assay and flow cytometry analysis, respectively, in P12 cells. Caspase-3 activity, the levels of tumor necrosis factor-α and interleukin-1β and the production of reactive oxygen species (ROS) were severally determined by caspase-3 activity assay, Enzyme-linked immunosorbent assay and ROS detection assay in P12 cells. The binding relationship between miR-455-3p and SNHG15 or TP53INP1 was predicted by starbase online database, and identified by dual-luciferase reporter, RNA pull-down or RNA immunoprecipitation assay. SNHG15 expression and the mRNA and protein levels of TP53INP1 were dramatically upregulated, while miR-455-3p expression was apparently downregulated in OGD/R-induced PC12 cells. SNHG15 silencing hindered the effects of OGD/R treatment on cell viability, apoptosis, inflammation and oxidative in PC12 cells; however, these impacts were restored after miR-455-3p inhibitor transfection. Additionally, SNHG15 acted as a sponge of miR-455-3p and miR-455-3p bound to TP53INP1. SNHG15 contributed to OGD/R-induced neuron injury by regulating miR-455-3p/TP53INP1 axis, which provided a novel insight to study lncRNA-directed therapy in ischemia stoke.

Up-regulating lncRNA OIP5-AS1 protects neuron injury against cerebral hypoxia-ischemia induced inflammation and oxidative stress in microglia/macrophage through activating CTRP3 via sponging miR-186-5p

BACKGROUND

Inflammation and oxidative stress is closely associated with the development of ischemic brain stroke. Opa-interacting protein 5 antisense RNA 1 (OIP5-AS1), a novel identified long non-coding RNA (lncRNA), has been suggested to play an important role in the development of many types of human cancers. However, the functional involvement of OIP5-AS1 in ischemic stroke is still unknown.

METHODS

Quantitative real-time polymerase chain reaction and /or western blot were conducted to determine the expression profiles of OIP5-AS1, C1q/TNF-related protein 3 (CTRP3) and miR-186-5p in the serum of stroke patients, as well as in the ischemic penumbra of rats with middle cerebral artery occlusion/reperfusion (MCAO/R) injury and microglial cells treated with oxygen glucose deprivation/re-oxygenation (OGD/R). Upon selective regulation of OIP5-AS1 and miR-186-5p, the inflammation and oxidative stress responses in microglia/macrophage as well as neurologic functions in MCAO/R rats were detected. Furthermore, the interactions between OIP5-AS1 and miR-186-5p, miR-186-5p and CTRP3 were investigated by RNA immunoprecipitation (RIP) assay, luciferase report assay and bioinformation anaylsis.

RESULTS

We observed markedly increased infarct volume, neuronal apoptosis, inflammation and oxidative stress responses in the infarcted lesions of MCAO/R rats, in line with down-regulated levels of OIP5-AS1 and CTRP3 while up-regulated miR-186-5p. Functional studies demonstrated that up-regulation of OIP5-AS1 attenuated infarct volume, neuronal apoptosis, microglia/macrophage inflammation and oxidative stress responses induced by MCAO/R or OGD/R. In terms of mechanism, we revealed that OIP5-AS1-miR-186-5p-CTRP3 axis played a vital role in modulating microglia/macrophage activation and neuronal apoptosis.

CONCLUSION

Up-regulating lncRNA OIP5-AS1 protects neuron injury against MCAO/R induced inflammation and oxidative stress in microglia/macrophage through activating CTRP3 via sponging miR-186-5p.

Long Noncoding RNA/Circular RNA-miRNA-mRNA Axes in Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) elicits tissue injury involved in a wide range of pathologies. Multiple studies have demonstrated that noncoding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), participate in the pathological development of IRI, and they may act as biomarkers, therapeutic targets, or prognostic indicators. Nonetheless, the specific molecular mechanisms of ncRNAs in IRI have not been completely elucidated. Regulatory networks among lncRNAs/circRNAs, miRNAs, and mRNAs have been the focus of attention in recent years. Studies on the underlying molecular mechanisms have contributed to the discovery of therapeutic targets or strategies in IRI. In this review, we comprehensively summarize the current research on the lncRNA/circRNA-miRNA-mRNA axes and highlight the important role of these axes in IRI.

Downregulation of Long Noncoding RNA TUG1 Attenuates MTDH-Mediated Inflammatory Damage via Targeting miR-29b-1-5p After Spinal Cord Ischemia Reperfusion

Long noncoding RNAs and microRNAs (miRNAs) play a vital role in spinal cord ischemia reperfusion (IR) injury. The aim of this study was to identify the potential interactions between taurine upregulated gene 1 (TUG1) and miRNA-29b-1-5p in a rat model of spinal cord IR. The IR injury was established by 14-minute occlusion of aortic arch. TUG1 and metadherin (MTDH) knockdown were induced by respective siRNAs, and miR-29b-1-5p expression was modulated using specific inhibitor or mimics. The interactions between TUG1, miR-29b-1-5p, and the target genes were determined using the dual-luciferase reporter assay. We found that IR respectively downregulated and upregulated miR-29b-1-5p and TUG1, and significantly increased MTDH expression. MTDH was predicted as a target of miR-29b-1-5p and its knockdown downregulated NF-κB and IL-1β levels. A direct interaction was observed between TUG1 and miR-29b-1-5p, and knocking down TUG1 upregulated the latter. Furthermore, overexpression of miR-29b-1-5p or knockdown of TUG1 alleviated blood-spinal cord barrier leakage and improved hind-limb motor function by suppressing MTDH and its downstream pro-inflammatory cytokines. Knocking down TUG1 also alleviated MTDH/NF-κB/IL-1β pathway-mediated inflammatory damage after IR by targeting miR-29b-1-5p, whereas blocking the latter reversed the neuroprotective effect of TUG1 knockdown and restored MTDH/NF-κB/IL-1β levels.

Inhibition of LncRNA MALAT1 Attenuates Cerebral Ischemic Reperfusion Injury via Regulating AQP4 Expression

Stroke is one of the leading causes of mortality and disability worldwide. Long noncoding RNAs (lncRNAs) including MALAT1 have been shown to have critical roles in cerebral ischemia reperfusion injury (CIRI). However, the underlying mechanism of MALAT1 in CIRI has not been elucidated. The present study aimed to investigate the function and potential regulatory mechanism of MALAT1 in cerebral ischemic reperfusion injury. We established the middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation/reoxygenation (OGD/RX) model in vivo and in vitro, and then Cell Counting Kit-8 (CCK-8), RT-qPCR, flow cytometry analysis, lactate dehydrogenase (LDH) analysis, and 2,3,5-triphenyltetrazolium chloride (TTC) staining were used to examine cell viability, MALAT1, aquaporin-4 (AQP4) expression, LDH release, and infarct volume, respectively. The level of AQP4 was remarkably upregulated in CIRI 24 h/48 h or OGD/RX 24 h/48 h compared with the sham group. Knockdown of AQP4 could alleviate OGD/RX-induced injury through enhancing cell viability and reducing LDH release and the rate of apoptotic cells. Furthermore, we found that MALAT1 was also increased in OGD/RX 24 h/48 h and silencing of MALAT1 could decrease AQP4. Inhibition of MALAT1 could also protect OGD/RX-induced injury, while the protective effect of MALAT1 siRNA on cerebral ischemic reperfusion was disappeared after transfection with AQP4 plasmid, indicating that MALAT1 may play a protective role in brain stroke through regulating AQP4. Taken together, our study provides evidence that MALAT1 is involved in ischemic stroke by inhibiting AQP4. Therefore, MALAT1 may serve as a potential target for therapeutic intervention in ischemic brain injury.

LncRNA Oprm1 overexpression attenuates myocardial ischemia/reperfusion injury by increasing endogenous hydrogen sulfide via Oprm1/miR-30b-5p/CSE axis

AIMS

Ischemia/reperfusion (I/R) injury largely limits the efficacy of revascularization in acute myocardial infarction. Long noncoding RNA (lncRNA) Oprm1 is protective in cerebral I/R injury. This study aimed to investigate the effect of lncRNA Oprm1 on myocardial I/R injury and its mechanism.

MAIN METHODS

We ligated and then released the left anterior descending coronary artery of adult male rats to build the I/R model in vivo. At the same time, an H9c2 cardiomyocytes hypoxia-reoxygenation (H/R) model was also used. Myocardial infarction area, cardiac function, histology, TUNEL staining, cell viability, and vital protein expression was conducted and compared.

KEY FINDINGS

LncRNA Oprm1 was significantly down-regulated in the I/R injury model. When administered with the AAV9-Oprm1 vector, the myocardial injury and cardiac function were mitigated and preserved, with apoptosis reduced. The cystathionine-γ-lyase (CSE) expression and hydrogen sulfide (H₂S) expression were increased. The dual-luciferase reporter gene revealed the targeted relationship between lncRNA Oprm1 and miR-30b-5p. In H9c2 cardiomyocytes models, the miR-30b-5p blocked the protective effect of lncRNA Oprm1 on H/R injury, when Bcl-2, Bcl-xl was down-regulated, and HIF-1α, Bnip-3, Caspase-3, and Caspase-9 up-regulated.

SIGNIFICANCE

LncRNA Oprm1can competitively combines with miR-30b-5p, which down-regulates the expression of CSE. When administered with lncRNA Oprm1, increased endogenous H₂S can reduce apoptosis and protect the myocardium from I/R injury via activating PI3K/Akt pathway and inhibiting HIF1-α activity.

LncRNA TUG1 alleviates cardiac hypertrophy by targeting miR-34a/DKK1/Wnt-β-catenin signalling

The current study was designed to explore the role and underlying mechanism of lncRNA taurine up‐regulated gene 1 (TUG1) in cardiac hypertrophy. Mice were treated by transverse aortic constriction (TAC) surgery to induce cardiac hypertrophy, and cardiomyocytes were treated by phenylephrine (PE) to induce hypertrophic phenotype. Haematoxylin‐eosin (HE), wheat germ agglutinin (WGA) and immunofluorescence (IF) were used to examine morphological alterations. Real‐time PCR, Western blots and IF staining were used to detect the expression of RNAs and proteins. Luciferase assay and RNA pull‐down assay were used to verify the interaction. It is revealed that TUG1 was up‐regulated in the hearts of mice treated by TAC surgery and in PE‐induced cardiomyocytes. Functionally, overexpression of TUG1 alleviated cardiac hypertrophy both in vivo and in vitro. Mechanically, TUG1 sponged and sequestered miR‐34a to increase the Dickkopf 1 (DKK1) level, which eventually inhibited the activation of Wnt/β‐catenin signalling. In conclusion, the current study reported the protective role and regulatory mechanism of TUG1 in cardiac hypertrophy and suggested that TUG1 may serve as a novel molecular target for treating cardiac hypertrophy.

Long noncoding RNA TUG1 contributes to cerebral ischaemia/reperfusion injury by sponging mir-145 to up-regulate AQP4 expression

Emerging studies have shown that long noncoding RNA (lncRNA) TUG1 (taurine-up-regulated gene 1) plays critical roles in multiple biological processes. However, the expression and function of lncRNA TUG1 in cerebral ischaemia/reperfusion injury have not been reported yet. In this study, we found that LncRNA TUG1 expression was significantly up-regulated in cultured MA-C cells exposed to OGD/R injury, while similar results were also observed in MCAO model. Mechanistically, knockdown of TUG1 decreased lactate dehydrogenase levels and the ratio of apoptotic cells and promoted cell survival in vitro. Moreover, knockdown of TUG1 decreased AQP4 (encoding aquaporin 4) expression to attenuate OGD/R injury. TUG1 could interact directly with miR-145, and down-regulation of miR-145 could efficiently reverse the function of TUG1 siRNA on AQP4 expression. Finally, the TUG1 shRNA reduced the infarction area and cell apoptosis in I/R mouse brains in vivo. In summary, our results suggested that lncRNA TUG1 may function as a competing endogenous RNA (ceRNA) for miR-145 to induce cell damage, possibly providing a new therapeutic target in cerebral ischaemia/reperfusion injury.