Long noncoding RNA-MEG3 contributes to myocardial ischemia-reperfusion injury through suppression of miR-7-5p expression

m6A-Induced lncRNA MEG3 Promotes Cerebral Ischemia-Reperfusion Injury Via Modulating Oxidative Stress and Mitochondrial Dysfunction by hnRNPA1/Sirt2 Axis

Ischemic stroke remains one of the major causes of serious disability and death globally. LncRNA maternally expressed gene 3 (MEG3) is elevated in middle cerebral artery occlusion/reperfusion (MCAO/R) rats and oxygen-glucose deprivation/reperfusion (OGD/R)-treated neurocytes cells. The objective of this study is to investigate the mechanism underlying MEG3-regulated cerebral ischemia/reperfusion (I/R) injury. MCAO/R mouse model and OGD/R-treated HT-22 cell model were established. The cerebral I/R injury was monitored by TTC staining, neurological scoring, H&E and TUNEL assay. The levels of MEG3, hnRNPA1, Sirt2 and other key molecules were detected by qRT-PCR and western blot. Mitochondrial dysfunction was assessed by transmission Electron Microscopy (TEM), JC-1 and MitoTracker staining. Oxidative stress was monitored using commercial kits. Bioinformatics analysis, RIP, RNA pull-down assays and RNA FISH were employed to detect the interactions among MEG3, hnRNPA1 and Sirt2. The m6A modification of MEG3 was assessed by MeRIP-qPCR. MEG3 promoted MCAO/R-induced brain injury by modulating mitochondrial fragmentation and oxidative stress. It also facilitated OGD/R-induced apoptosis, mitochondrial dysfunction and oxidative stress in HT-22 cells. Mechanistically, direct associations between MEG3 and hnRNPA1, as well as between hnRNPA1 and Sirt2, were observed in HT-22 cells. MEG3 regulated Sirt2 expression in a hnRNPA1-dependent manner. Functional studies showed that MEG3/Sirt2 axis contributed to OGD/R-induced mitochondrial dysfunction and oxidative stress in HT-22 cells. Additionally, METTL3 was identified as the m6A transferase responsible for the m6A modification of MEG3. m6A-induced lncRNA MEG3 promoted cerebral I/R injury via modulating oxidative stress and mitochondrial dysfunction by hnRNPA1/Sirt2 axis.

Depletion of microRNA-92a Enhances the Role of Sevoflurane Treatment in Reducing Myocardial Ischemia-Reperfusion Injury by Upregulating KLF4

OBJECTIVE

As some articles have highlighted the role of microRNA-92a (miR-92a) in myocardial ischemia-reperfusion injury (MI/RI), this article aimed to investigate the effect of miR-92a on Sevoflurane (Sevo)-treated MI/RI via regulation of Krüppel-like factor 4 (KLF4).

METHODS

An MI/RI rat model was established by ligating the left anterior descending coronary artery. The cardiac function, pathological changes of myocardial tissues, inflammatory response, oxidative stress and cardiomyocyte apoptosis in MI/RI rats were determined. KLF4 and miR-92a expression was detected in the myocardial tissue of rats, and the target relationship between miR-92a and KLF4 was confirmed.

RESULTS

Sevo treatment alleviated myocardial damage, inflammatory response, oxidative stress response, and cardiomyocyte apoptosis, and improved cardiac function in MI/RI rats. miR-92a increased and KLF4 decreased in the myocardial tissue of MI/RI rats. KLF4 was targeted by miR-92a. Downregulation of miR-92a or upregulation of KLF4 further enhanced the effect of Sevo treatment on MI/RI.

CONCLUSION

This study suggests that depletion of miR-92a promotes upregulation of KLF4 to improve cardiac function, reduce cardiomyocyte apoptosis and further enhance the role of Sevo treatment in alleviating MI/RI.

Niraparib restrains prostate cancer cell proliferation and metastasis and tumor growth in mice by regulating the lncRNA MEG3/miR-181-5p/GATA6 pathway

Background

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi), have gained approval for treating patients with castration-resistant prostate cancer (CRPC). Maternally expressed gene 3 (MEG3), a long non-coding RNA (lncRNA), plays a role in inhibiting tumorigenesis through regulating DNA repair genes. This study aimed to investigate the association between the anti-prostate cancer (PCa) effect of niraparib, a representative PARPi, and MEG3 expression, as well as explore the downstream pathway involved.

Methods

The levels of MEG3, miR-181-5p, GATA binding protein 6 (GATA6) in clinical samples from PCa patients were accessed by RT-qPCR. PC3 cells were treated with niraparib, and the expression of MEG3, miR-181-5p, GATA6 expression was tested. PC3 cell proliferation, migration, and invasion were tested by CCK-8, wound healing, and Transwell assays, respectively. The bindings between miR-181-5p and MEG3/GATA6 were determined by dual-luciferase reporter gene assay. Furthermore, rescue experiments were conducted to investigate the underlying mechanism of MEG3/miR-181-5p/GATA6 axis in PCa progression. Additionally, mice were injected with PC3 cells transfected with sh-MEG3 and treated with niraparib, and the xenograft tumor growth was observed.

Results

MEG3 and GATA6 were upregulated and miR-181-5p was downregulated in PCa patients. Niraparib treatment substantially upregulated MEG3 and GATA6, and downregulated miR-181-5p expression in PCa cells. Niraparib effectively restrained PC3 cell proliferation, migration, and invasion. MiR-181-5p targeted to MEG3, and the inhibitory effects of MEG3 overexpression on PC3 cell proliferation and metastasis were abrogated by miR-181-5p overexpression. Moreover, GATA6 was identified as a target of miR-181-5p, and GATA6 silencing abolished the inhibitory effects of miR-181-5p inhibition on PC3 cell proliferation and metastasis. Besides, MEG3 silencing could abrogate niraparib-mediated tumor growth inhibition in mice.

Conclusions

Niraparib restrains prostate cancer cell proliferation and metastasis and tumor growth in mice by regulating the lncRNA MEG3/miR-181-5p/GATA6 pathway.

Depletion of lncRNA MEG3 Ameliorates Imatinib-Induced Injury of Cardiomyocytes via Regulating miR-129-5p/HMGB1 Axis

Imatinib is a classical targeted drug to treat chronic myeloid leukemia (CML). However, it shows cardiotoxicity, which limits its clinical application. Long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) shows proapoptotic properties in human cells. This study is performed to investigate whether targeting MEG3 can attenuate imatinib-mediated cardiotoxicity to cardiomyocytes. In this work, H9c2 cells were divided into four groups: control group, hypoxia group, hypoxia + imatinib, and hypoxia + imatinib + MEG3 knockdown group. MEG3 and microRNA-129-5p (miR-129-5p) expression levels were detected by the quantitative real-time PCR (qRT-PCR). The viability and apoptosis of H9c2 cells were then evaluated by cell counting kit-8 (CCK-8), flow cytometry, and TUNEL assays. The targeting relationships between MEG3 and miR-129-5p, between miR-129-5p and high-mobility group box 1 (HMBG1), were validated by dual-luciferase reporter assay and RNA Immunoprecipitation (RIP) assay. The protein expression level of HMGB1 was detected by western blot. It was revealed that, Imatinib-inhibited cell viability and aggravated the apoptosis of H9c2 cells cultured in hypoxic condition, and MEG3 knockdown significantly counteracted this effect. MiR-129-5p was a downstream target of MEG3 and it directly targeted HMGB1, and knockdown of MEG3 inhibited HMGB1 expression in H9c2 cells. In conclusion, targeting MEG3 ameliorates imatinib-induced injury of cardiomyocytes via regulating miR-129-5p/HMGB1 axis.

METTL14 promotes doxorubicin-induced cardiomyocyte ferroptosis by regulating the KCNQ1OT1-miR-7-5p-TFRC axis

Doxorubicin (DOX) has toxic effects on the heart, causing cardiomyopathy and heart injury, but the underlying mechanisms of these effects require further investigation. This study investigated the role of DOX in promoting ferroptosis to induce myocardial injury. AC16 cardiomyocyte and neonatal rat ventricle cardiomyocytes were used as an in vitro model to study the molecules involved in myocardial injury using gene silencing, ectopic expression, and RNA immunoprecipitation. Messenger RNA and protein level analyses showed that DOX treatment resulted in the upregulation of methyltransferase-like 14 (METTL14), which catalyzes the m6A modification of the long non-coding RNA KCNQ1OT1, a miR-7-5p sponge. The RNA-binding protein IGF2BP1 is associated with KCNQ1OT1 to increase its stability and robustly inhibit miR-7-5p activity. Furthermore, a lack of miR-7-5p expression led to increased levels of transferrin receptor, promoting the uptake of iron and production of lipid reactive oxygen species and demonstrating that DOX-induced ferroptosis occurs in AC16 cells. Additionally, we found that miR-7-5p targets METTL14 in AC16 cells. Meanwhile, the role of METTL14/KCNQ1OT1/miR-7-5p axis in regulating ferroptosis in neonatal rat ventricle cardiomyocytes was also confirmed. Our results indicate that selectively inhibiting ferroptosis mediated by a METTL14/KCNQ1OT1/miR-7-5p positive feedback loop in cardiomyocytes could provide a new therapeutic approach to control DOX-induced cardiac injury.

The multifaceted biology of lncR-Meg3 in cardio-cerebrovascular diseases

Cardio-cerebrovascular disease, related to high mortality and morbidity worldwide, is a type of cardiovascular or cerebrovascular dysfunction involved in various processes. Therefore, it is imperative to conduct additional research into the pathogenesis and new therapeutic targets of cardiovascular and cerebrovascular disorders. Long non-coding RNAs (lncRNAs) have multiple functions and are involved in nearly all cellular biological processes, including translation, transcription, signal transduction, and cell cycle control. LncR-Meg3 is one of them and is becoming increasingly popular. By binding proteins or directly or competitively binding miRNAs, LncR-Meg3 is involved in apoptosis, inflammation, oxidative stress, endoplasmic reticulum stress, epithelial-mesenchymal transition, and other processes. Recent research has shown that LncR-Meg3 is associated with acute myocardial infarction and can be used to diagnose this condition. This article examines the current state of knowledge regarding the expression and regulatory function of LncR-Meg3 in relation to cardiovascular and cerebrovascular diseases. The abnormal expression of LncR-Meg3 can influence neuronal cell death, inflammation, apoptosis, smooth muscle cell proliferation, etc., thereby aggravating or promoting the disease. In addition, we review the bioactive components that target lncR-Meg3 and propose some potential delivery vectors. A comprehensive and in-depth analysis of LncR-Meg3’s role in cardiovascular disease suggests that targeting LncR-Meg3 may be an alternative therapy in the near future, providing new options for slowing the progression of cardiovascular disease.

Circulatory long noncoding RNAs (circulatory-LNC-RNAs) as novel biomarkers and therapeutic targets in cardiovascular diseases: Implications for cardiovascular diseases complications

Cardiovascular diseases (CVDs) are a group of disorders with major global health consequences. The prevalence of CVDs continues to grow due to population-aging and lifestyle modifications. Non-coding RNAs (ncRNAs) as key regulators of cell signaling pathways have gained attention in the occurrence and development of CVDs. Exosomal-lncRNAs (exos-lncRNAs) are emerging biomarkers due to their high sensitivity and specificity, stability, accuracy and accessibility in the biological fluids. Recently, circulatory and exos-based-lncRNAs are emerging and novel bio-tools in various pathogenic conditions. It is worth mentioning that dysregulation of these molecules has been found in different types of CVDs. In this regard, we aimed to discuss the knowledge gaps and suggest research priorities regarding circulatory and exos-lncRNAs as novel bio-tools and therapeutic targets for CVDs.

LncRNA MEG3: Potential stock for precision treatment of cardiovascular diseases

The prevalence and mortality rates of cardiovascular diseases are increasing, and new treatment strategies are urgently needed. From the perspective of basic pathogenesis, the occurrence and development of cardiovascular diseases are related to inflammation, apoptosis, fibrosis and autophagy of cardiomyocytes, endothelial cells and other related cells. The involvement of maternally expressed gene 3 (MEG3) in human disease processes has been increasingly reported. P53 and PI3K/Akt are important pathways by which MEG3 participates in regulating cell apoptosis. MEG3 directly or competitively binds with miRNA to participate in apoptosis, inflammation, oxidative stress, endoplasmic reticulum stress, EMT and other processes. LncRNA MEG3 is mainly involved in malignant tumors, metabolic diseases, immune system diseases, cardiovascular and cerebrovascular diseases, etc., LncRNA MEG3 has a variety of pathological effects in cardiomyocytes, fibroblasts and endothelial cells and has great clinical application potential in the prevention and treatment of AS, MIRI, hypertension and HF. This paper will review the research progress of MEG3 in the aspects of mechanism of action, other systemic diseases and cardiovascular diseases, and point out its great potential in the prevention and treatment of cardiovascular diseases. lncRNAs also play a role in endothelial cells. In addition, lncRNA MEG3 has shown biomarker value, prognostic value and therapeutic response measurement in tumor diseases. We boldly speculate that MEG3 will play a role in the emerging discipline of tumor heart disease.

Illuminating the Molecular Intricacies of Exosomes and ncRNAs in Cardiovascular Diseases: Prospective Therapeutic and Biomarker Potential

Cardiovascular diseases (CVDs) are one of the leading causes of death worldwide. Accumulating evidences have highlighted the importance of exosomes and non-coding RNAs (ncRNAs) in cardiac physiology and pathology. It is in general consensus that exosomes and ncRNAs play a crucial role in the maintenance of normal cellular function; and interestingly it is envisaged that their potential as prospective therapeutic candidates and biomarkers are increasing rapidly. Considering all these aspects, this review provides a comprehensive overview of the recent understanding of exosomes and ncRNAs in CVDs. We provide a great deal of discussion regarding their role in the cardiovascular system, together with providing a glimpse of ideas regarding strategies exploited to harness their potential as a therapeutic intervention and prospective biomarker against CVDs. Thus, it could be envisaged that a thorough understanding of the intricacies related to exosomes and ncRNA would seemingly allow their full exploration and may lead clinical settings to become a reality in near future.

Single-Cell RNA Sequencing Reveals Distinct Cardiac-Derived Stromal Cell Subpopulations

Human cardiac-derived c-kit+ stromal cells (CSCs) have demonstrated efficacy in preclinical trials for the treatment of heart failure and myocardial dysfunction. Unfortunately, large variability in patient outcomes and cell populations remains a problem. Previous research has demonstrated that the reparative capacity of CSCs may be linked to the age of the cells: CSCs derived from neonate patients increase cardiac function and reduce fibrosis. However, age-dependent differences between CSC populations have primarily been explored with bulk sequencing methods. In this work, we hypothesized that differences in CSC populations and subsequent cell therapy outcomes may arise from differing cell subtypes within donor CSC samples. We performed single-cell RNA sequencing on four neonatal CSC (nCSC) and five child CSC (cCSC) samples. Subcluster analysis revealed cCSC-enriched clusters upregulated in several fibrosis- and immune response-related genes. Module-based analysis identified upregulation of chemotaxis and ribosomal activity-related genes in nCSCs and upregulation of immune response and fiber synthesis genes in cCSCs. Further, we identified versican and integrin alpha 2 as potential markers for a fibrotic cell subtype. By investigating differences in patient-derived CSC populations at the single-cell level, this research aims to identify and characterize CSC subtypes to better optimize CSC-based therapy and improve patient outcomes.

Evaluating the Role of lncRNAs in the Incidence of Cardiovascular Diseases in Androgenetic Alopecia Patients

Hair loss occurs in patients with Androgenetic Alopecia (AGA). The pattern of hair loss is different between men and women. The main cause of hair loss is increased cell apoptosis and decreased regeneration, proliferation and differentiation processes in hair follicles. Long Non-Coding RNAs (lncRNAs) are one of the most important molecules that regulate the processes of apoptosis, regeneration, proliferation and differentiation in hair follicles. Since studies have shown that lncRNAs can be effective in the development of cardiotoxicity and induction of cardiovascular disease (CVD); so effective lncRNAs in the regulation of regeneration, proliferation, differentiation and apoptosis of hair follicles can be involved in the development of CVD in AGA patients with. Therefore, this study investigated the lncRNAs involved in increasing apoptosis and reducing the processes of regeneration, proliferation and differentiation of hair follicles. The aim of the current study was to evaluate the role of lncRNAs as a risk factor in the incidence of CVD in AGA patients; it will help to design treatment strategies by targeting signaling pathways without any cardiotoxicity complications.

Long non-coding RNAs and microRNAs as crucial regulators in cardio-oncology

Cancer is one of the leading causes of morbidity and mortality worldwide. Significant improvements in the modern era of anticancer therapeutic strategies have increased the survival rate of cancer patients. Unfortunately, cancer survivors have an increased risk of cardiovascular diseases, which is believed to result from anticancer therapies. The emergence of cardiovascular diseases among cancer survivors has served as the basis for establishing a novel field termed cardio-oncology. Cardio-oncology primarily focuses on investigating the underlying molecular mechanisms by which anticancer treatments lead to cardiovascular dysfunction and the development of novel cardioprotective strategies to counteract cardiotoxic effects of cancer therapies. Advances in genome biology have revealed that most of the genome is transcribed into non-coding RNAs (ncRNAs), which are recognized as being instrumental in cancer, cardiovascular health, and disease. Emerging studies have demonstrated that alterations of these ncRNAs have pathophysiological roles in multiple diseases in humans. As it relates to cardio-oncology, though, there is limited knowledge of the role of ncRNAs. In the present review, we summarize the up-to-date knowledge regarding the roles of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in cancer therapy-induced cardiotoxicities. Moreover, we also discuss prospective therapeutic strategies and the translational relevance of these ncRNAs.

Long Noncoding RNAs Involved in Cardiomyocyte Apoptosis Triggered by Different Stressors

Cardiomyocytes are essential to maintain the normal cardiac function. Ischemia, hypoxia, and drug stimulation can induce pathological apoptosis of cardiomyocytes which eventually leads to heart failure, arrhythmia, and other cardiovascular diseases. Understanding the molecular mechanisms that regulate cardiomyocyte apoptosis is of great significance for the prevention and treatment of cardiovascular diseases. In recent years, more and more evidences reveal that long noncoding RNAs (lncRNAs) play important regulatory roles in myocardial cell apoptosis. They can modulate the expression of apoptosis-related genes at post-transcriptional level by altering the translation efficacy of target mRNAs or functioning as a precursor for miRNAs or competing for miRNA-mediated inhibition. Moreover, reversing the abnormal expression of lncRNAs can attenuate and even reverse the pathological apoptosis of cardiomyocytes. Therefore, apoptosis-related lncRNAs may become a potential new field for studying cardiomyocyte apoptosis and provide new ideas for the treatment of cardiovascular diseases.

Se alleviates homocysteine-induced fibrosis in cardiac fibroblasts via downregulation of lncRNA MEG3

Selenium (Se) is considered to have antioxidant properties, which are beneficial for heart condition. Hyperhomocysteinemia (HHCY) has been suggested to potentially lead to heart failure and is characterized by cardiac fibrosis; however, investigation on the role of Se and HHCY in cardiac fibrosis is rare. Since previous studies demonstrated the important role of the long non-coding RNA maternally expressed 3 (MEG3) in some heart diseases, the present study aimed to determine how Se and MEG3 might exert regulatory effects on HCY-induced fibrosis in cardiac fibroblasts (CFs). Mouse CFs were isolated and treated with HCY and Se. The expression of α-smooth muscle actin (α-SMA), collagen I and III was detected by western blotting to reflect CF fibrosis. Reverse transcription-quantitative PCR was performed to determine the expression levels of MEG3. Inflammation and oxidative stress responses were analyzed by measuring TNF-α, IL-1β (ELISA) and reactive oxygen species levels (using a commercial kit), respectively. Cell Counting Kit-8 was used to evaluate CF proliferation. Total and phosphorylated (p) expression of janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) was evaluated by western blotting. CFs were transfected with adenovirus expressing MEG3 short-hairpin RNA to knock down MEG3 expression. Se treatment downregulated the expression level of MEG3 in HCY-stimulated CFs, whilst inhibiting the inflammatory and oxidative stress response. Furthermore, Se inhibited the increased proliferation of CFs following HCY treatment. In addition, MEG3-knockdown in CFs could improve fibrosis caused by HCY. Furthermore, the ratios of p-JAK2/JAK2 and p-STAT3/STAT3 were decreased following treatment with Se or MEG3 silencing. Taken together, the findings from the present study suggested that Se may alleviate cardiac fibrosis by downregulating the expression of MEG3 and reducing the inflammatory and oxidative stress response in CFs. This suggests that Se may be a potential therapeutic option for treating cardiac fibrosis in the future.

Long Non-coding RNA MEG3 Promotes Pyroptosis in Testicular Ischemia-Reperfusion Injury by Targeting MiR-29a to Modulate PTEN Expression

Increasing evidence shows that the abnormal long non-coding RNAs (lncRNAs) expression is closely related to ischemia-reperfusion injury (I/R) progression. Studies have previously described that lncRNA MEG3 regulates pyroptosis in various organs I/R. Nevertheless, the related mechanisms of MEG3 in testicular I/R has not been clarified. The aim of this research is to unravel underlying mechanisms of the regulation of pyroptosis mediated by MEG3 during testicular I/R. We have established a testicular torsion/detorsion (T/D) model and an oxygen-glucose deprivation/reperfusion (OGD/R)-treated spermatogenic cell model. Testicular ischemic injury was assessed by H&E staining. Western blotting, quantitative real-time PCR, MDA, and SOD tests and immunohistochemistry measured the expression of MEG3 and related proteins and the level of ROS production in testicular tissues. Quantitative real-time PCR and western blotting determined the relative expression of MEG3, miR-29a, and relevant proteins in GC-1. Cell viability and cytotoxicity were measured by CCK-8 and LDH assays. Secretion and expression levels of inflammatory proteins were determined by ELISA, immunofluorescence and western blotting. The interaction among MEG3, miR-29a, and PTEN was validated through a dual luciferase reporter assay and Ago2-RIP. In this research, we identified that MEG3 was upregulated in animal specimens and GC-1. In loss of function or gain of function assays, we verified that MEG3 could promote pyroptosis. Furthermore, we found that MEG3 negatively regulated miR-29a expression at the posttranscriptional level and promoted PTEN expression, and further promoted pyroptosis. Therefore, we explored the interaction among MEG3, miR-29a and PTEN and found that MEG3 directly targeted miR-29a, and miR-29a targeted PTEN. Overexpression of miR-29a effectively eliminated the upregulation of PTEN induced by MEG3, indicating that MEG3 regulates PTEN expression by targeting miR-29a. In summary, our research indicates that MEG3 contributes to pyroptosis by regulating miR-29a and PTEN during testicular I/R, indicating that MEG3 may be a potential therapeutic target in testicular torsion.

Roles of noncoding RNAs in the initiation and progression of myocardial ischemia-reperfusion injury

The morbidity and mortality of myocardial ischemia-reperfusion injury (MIRI) have increased in modern society. Noncoding RNAs (ncRNAs), including lncRNAs, circRNAs, piRNAs and miRNAs, have been reported in a variety of studies to be involved in pathological initiation and developments of MIRI. Hence this review focuses on the current research regarding these ncRNAs in MIRI. We comprehensively introduce the important features of lncRNAs, circRNAs, piRNA and miRNAs and then summarize the published studies of ncRNAs in MIRI. A clarification of lncRNA-miRNA-mRNA, lncRNA-transcription factor-mRNA and circRNA-miRNA-mRNA axes in MIRI follows, to further elucidate the crucial roles of ncRNAs in MIRI. Bioinformatics analysis has revealed the biological correlation of mRNAs with MIRI. We provide a comprehensive perspective for the roles of these ncRNAs and their related networks in MIRI, providing a theoretical basis for preclinical and clinical studies on ncRNA-based gene therapy for MIRI treatment.

Long Noncoding RNAs in Myocardial Ischemia-Reperfusion Injury

Following an acute myocardial infarction, reperfusion therapy is currently the most effective way to save the ischemic myocardium; however, restoring blood flow may lead to a myocardial ischemia-reperfusion injury (MIRI). Recent studies have confirmed that long-chain noncoding RNAs (LncRNAs) play important roles in the pathophysiology of MIRIs. These LncRNA-mediated roles include cardiomyocyte apoptosis, autophagy, necrosis, oxidative stress, inflammation, mitochondrial dysfunction, and calcium overload, which are regulated through the expression of target genes. Thus, LncRNAs may be used as clinical diagnostic markers and therapeutic targets to treat or prevent MIRI. This review evaluates the research on LncRNAs involved in MIRIs and provides new ideas for preventing and treating this type of injury.

Involvement of non‑coding RNAs in the pathogenesis of myocardial ischemia/reperfusion injury (Review)

Myocardial ischemia/reperfusion injury (MIRI) may cause myocardial stunning, reperfusion arrhythmia, no‑reflow phenomenon and lethal reperfusion injury, which has a significant effect on the prognosis of patients undergoing thrombolytic agent therapy and percutaneous coronary intervention. Increasing evidence suggests that apoptosis, innate inflammation, oxidative stress, calcium overload and autophagy are involved in the pathogenesis of MIRI. Recent advancements in RNA sequencing technologies and genome‑wide analyses led to the finding of small non‑coding RNAs (ncRNAs). ncRNAs modulate cellular processes such as signal transduction, transcription, chromatin remodeling and post‑transcriptional modification. The effects of ncRNAs on cellular biology is more considerable than initially expected, and thus ncRNAs have gained increasing attention and focus in modern medical research. There are several types of ncRNAs, such as microRNAs (miRNAs), long non‑coding RNAs (lncRNAs) and circular RNAs (circRNAs), which have been shown to regulate gene expression at the transcription, post‑transcription and epigenetic levels. Dysregulation of ncRNAs, including miRNAs, lncRNAs and circRNAs, may participate in the molecular mechanisms of MIRI. The present review summarizes the characteristics and biological roles of miRNAs, lncRNAs and circRNAs, with particular emphasis on their role in MIRI, which show the novel complexity of ischemic hearts and may offer valuable insights into the pathogenesis of MIRI.

c-MYC-induced long noncoding RNA MEG3 aggravates kidney ischemia-reperfusion injury through activating mitophagy by upregulation of RTKN to trigger the Wnt/β-catenin pathway

Ischemia-reperfusion injury (IRI)-induced acute kidney injury (AKI) is a life-threatening disease. The activation of mitophagy was previously identified to play an important role in IRI. Maternally expressed 3 (MEG3) can promote cerebral IRI and hepatic IRI. The present study was designed to study the role of MEG3 in renal IRI. Renal IRI mice models were established, and HK-2 cells were used to construct the in vitro models of IRI. Hematoxylin-eosin staining assay was applied to reveal IRI-triggered tubular injury. MitoTracker Green FM staining and an ALP kit were employed for detection of mitophagy. TdT-mediated dUTP-biotin nick-end labeling assay was used to reveal cell apoptosis. The results showed that renal cortex of IRI mice contained higher expression of MEG3 than that of sham mice. MEG3 expression was also elevated in HK-2 cells following IRI, suggesting that MEG3 might participate in the development of IRI. Moreover, downregulation of MEG3 inhibited the apoptosis of HK-2 cells after IRI. Mitophagy was activated by IRI, and the inhibition of MEG3 can restore mitophagy activity in IRI-treated HK-2 cells. Mechanistically, we found that MEG3 can bind with miR-145-5p in IRI-treated cells. In addition, rhotekin (RTKN) was verified to serve as a target of miR-145-5p. MEG3 upregulated RTKN expression by binding with miR-145-5p. Further, MEG3 activated the Wnt/β-catenin pathway by upregulation of RTKN. The downstream effector of Wnt/β-catenin pathway, c-MYC, served as the transcription factor to activate MEG3. In conclusion, the positive feedback loop of MEG3/miR-145-5p/RTKN/Wnt/β-catenin/c-MYC promotes renal IRI by activating mitophagy and inducing apoptosis, which might offer a new insight into the therapeutic methods for renal IRI in the future.

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.

Long noncoding RNA MEG3 contributes to dysfunction of brain microvascular endothelial cells after intracerebral hemorrhage by regulating the miR-1930-5p/Mllt1 axis

BACKGROUND

Intracerebral hemorrhage (ICH) is a subtype of stroke and causes disability and death worldwide. The roles of long noncoding RNAs (lncRNAs) in brain function and neurological diseases have been revealed. LncRNA maternally expressed gene 3 (MEG3) is involved in neurological impairment, but its role in ICH remains unknown.

AIMS

The aim of this research is to explore the role of MEG3 in ICH.

METHODS AND RESULTS

Here, we established an ICH mouse model via intracerebral injection of autologous blood. Primary brain microvascular endothelial cells (BMECs) were treated with oxygen-and-glucose-deprivation (OGD) plus hemin to establish the model in vitro. We observed that MEG3 expression was significantly upregulated in both ICH mouse model and OGD/hemin (OGD/H) induced BMECs. The downregulation of MEG3 suppressed cell apoptosis and the activation of NOD-like receptor family protein 3 (NLRP3) inflammasome in OGD/H-induced BMECs. In ICH mice, MEG3 downregulation inhibited cell apoptosis and improved brain dysfunction. Mechanistically, MEG3 was confirmed to act as a molecular sponge for microRNA (miR)-1930-5p, and Mllt1 was a downstream target for miR-1930-5p. MEG3 competitively bound with miR-1930-5p to upregulate Mllt1. We further verified that Mllt1 overexpression reversed the inhibitory effect of miR-1930-5p in OGD/H-induced BMECs.

CONCLUSIONS

In conclusion, lncRNA MEG3 promoted the dysfunction of BMECs by modulating the miR-1930-5p/Mllt1 axis, which provides a potential target in gene therapy for brain injury following ICH.

Icariside II protects cardiomyocytes from hypoxia‑induced injury by upregulating the miR‑7‑5p/BTG2 axis and activating the PI3K/Akt signaling pathway

Icariside II (ICS II) has been reported to have protective effects against oxidative stress. However, whether ICS II protects cardiomyocytes from myocardial infarction (MI), and the associated underlying mechanisms, remain to be elucidated. Therefore, the current study investigated the effects of ICS II on hypoxia‑injured H9c2 cells, as well as the associated molecular mechanisms. A hypoxic injury model was established to emulate the effects of MI. The effects of ICS II on the proliferation of rat cardiomyocyte H9c2 cells were assessed with cell counting kit‑8 assays. The apoptotic status of the cells was assessed by flow cytometry, and the expression of apoptosis‑related proteins was analyzed by western blotting. A microRNA (miRNA/miR) microarray was used to quantify the differential expression of miRNAs after ICS II treatment, and the levels of miR‑7‑5p were further quantified by reverse transcription‑quantitative PCR. Whether ICS II affected hypoxia‑injured cells via miR‑7‑5p was subsequently examined, and the target of miR‑7‑5p was also investigated by bioinformatics analysis and luciferase reporter assays. The effects of ICS II on the PI3K/Akt pathway were then evaluated by western blot analysis. Hypoxia treatment decreased viability and the migration and invasion abilities of H9c2 cells, and also induced apoptosis. ICS II significantly increased viability and reduced hypoxia‑associated apoptosis. Moreover, ICS II treatment led to the upregulation of miR‑7‑5p, and the protective effects of ICS II were found to rely on miR‑7‑5p. Moreover, BTG anti‑proliferation factor (BTG2) was identified as a direct target of miR‑7‑5p, and overexpression of BTG2 inhibited the protective effects of miR‑7‑5p. Finally, ICS II treatment resulted in the activation of the PI3K/Akt signaling pathway, which is essential for the survival of H9c2 cells under hypoxic conditions. In summary, ICS II reduces hypoxic injury in H9c2 cells via the miR‑7‑5p/BTG2 axis and activation of the PI3K/Akt signaling pathway.

Lnc-MEG3 acts as a potential biomarker for predicting increased disease risk, systemic inflammation, disease severity, and poor prognosis of sepsis via interacting with miR-21

BACKGROUND

This study aimed to investigate the correlations of long non-coding RNA maternally expressed gene 3 (lnc-MEG3), microRNA (miR)-21, and lnc-MEG3/miR-21 axis with disease risk, inflammation, disease severity, and 28-day mortality of sepsis.

METHODS

Totally, 219 sepsis patients and 219 health controls (HCs) were enrolled. Plasma samples were obtained from sepsis patients within 24 hours after admission and from HCs on enrollment to detect lnc-MEG3 and miR-21 expressions by real-time quantitative polymerase chain reaction.

RESULTS

The lnc-MEG3 expression and lnc-MEG3/miR-21 axis were increased, while miR-21 expression was decreased in sepsis patients compared with HCs. Lnc-MEG3 (area under the curve (AUC): 0.887, 95% confidence interval (CI): 0.856-0.917) and lnc-MEG3/miR-21 axis (AUC: 0.934, 95% CI: 0.909-0.958) had good values for predicting elevated sepsis risk, while miR-21 (AUC: 0.801, 95% CI: 0.758-0.844) presented a good predictive value for reduced sepsis risk. Furthermore, lnc-MEG3 expression and lnc-MEG3/miR-21 axis positively correlated with, whereas miR-21 expression negatively correlated with acute pathologic and chronic health evaluation II, sequential organ failure assessment score, serum creatinine, C-reactive protein, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-17 in sepsis patients. Additionally, lnc-MEG3 (AUC: 0.704, 95% CI: 0.626-0.783) and lnc-MEG3/miR-21 axis (AUC: 0.669, 95% CI: 0.589-0.750) exhibited acceptable values in predicting higher 28-day mortality risk, while miR-21 (AUC: 0.588, 95% CI: 0.505-0.672) presented a poor predictive value for lower 28-day mortality risk in sepsis patients.

CONCLUSION

Lnc-MEG3 might serve as a potential biomarker for the development, progression, and prognosis prediction of sepsis via interacting with miR-21.

Down-regulation of Xist and Mir-7a-5p improves LPS-induced myocardial injury

Background: X-inactive specific transcript (Xist) is a lncRNA, which plays a significant role in X-chromosome inactivation, regulates cell proliferation in tumor cells, and inhibits apoptosis in acute myocardial infarction. On the other hand, miR-7a-5p is involved in cardiomyocytes injury in myocardial ischemia/reperfusion. However, their roles in LPS-induced damage remain unclear. Objectives: This study aimed at using siRNA transfection and lentivirus infection to regulate the expression of xist and miR-7a-5p, and to evaluate their effects on LPS-induced myocardial damage. Method: Mice cardiomyocytes (MCM) cells were divided into six groups, namely the control group, the LPS group, the LPS + lncRNA^- group, the LPS + lncRNA⁺ group, the LPS + miRNA^- group, and the LPS + miRNA⁺ group. Quantitative real-time PCR (qRT-PCR) was performed to assay for the RNA expressions of xist, miR-7a-5p, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), and recombinant mitochondrial transcription factor A (Tfam) in all the groups. The ATP level was determined using the adenosine triphosphate (ATP) assay kit according to the manufacturer's instructions. Flow cytometry was performed to estimate the level of apoptosis and proliferation in cells in each group. Results: The level of xist in the myocardial cells was markedly higher in the LPS group compared with the control group; however, it was reduced in the LPS+ lncRNA^- group. There was no significant difference in the expression of xist among the LPS+miRNA^-, LPS+miRNA⁺, and LPS groups. Moreover, the expression of mir-7a-5p was significantly reduced in myocardial cells in the LPS group, and moderately reduced in the LPS+ miRNA^- group, but remarkably elevated in the LPS+ miRNA⁺ group (P<0.05). The expression of mir-7a-5p was comparably similar in the LPS+ lncRNA^- group, LPS+ lncRNA⁺ group, and LPS groups. Further, the levels of PGC-1a, and Tfam were determined. In the LPS group, the expression of PGC-1α was significantly reduced but elevated in the LPS+lncRNA^- and LPS+ miRNA^- groups (P<0.05). There was no significant difference in the level of PGC-1α among the LPS, LPS+ lncRNA⁺, and LPS+ miRNA⁺ groups. The expression of Tfam was markedly reduced in the LPS group (P < 0.05), but elevated after the suppression of xist and mir-7a-5p. The expression of Tfam was not significantly different among the LPS group, LPS+ lncRNA⁺ and LPS+ miRNA⁺ groups. Notably, overexpression of mir-7a-5p had a mild effect on the expression of Tfam in the LPS+ miRNA⁺ group compared with the control group. Besides, ATP expression in the LPS group was markedly reduced, but elevated after the inhibition of xist and mir-7a-5p. Suppressing the expression of xist or mir-7a-5p resulted in reduced cell apoptosis and increased cell proliferation. Conclusions: In this study, we established that down-regulation of xist and mir-7a-5p reduces apoptosis in response to LPS.