LncRNA Gm4419 Regulates Myocardial Ischemia/Reperfusion Injury Through Targeting the miR-682/TRAF3 Axis

Roles of flavonoids in ischemic heart disease: Cardioprotective effects and mechanisms against myocardial ischemia and reperfusion injury

BACKGROUND

Flavonoids are extensively present in fruits, vegetables, grains, and medicinal plants. Myocardial ischemia and reperfusion (MI/R) comprise a sequence of detrimental incidents following myocardial ischemia. Research indicates that flavonoids have the potential to act as cardioprotective agents against MI/R injuries. Several specific flavonoids, e.g., luteolin, hesperidin, quercetin, kaempferol, and puerarin, have demonstrated cardioprotective activities in animal models.

PURPOSE

The objective of this review is to identify the cardioprotective flavonoids, investigate their mechanisms of action, and explore their application in myocardial ischemia.

METHODS

A search of PubMed database and Google Scholar was conducted using keywords "myocardial ischemia" and "flavonoids". Studies published within the last 10 years reporting on the cardioprotective effects of natural flavonoids on animal models were analyzed.

RESULTS

A total of 55 natural flavonoids were identified and discussed within this review. It can be summarized that flavonoids regulate the following main strategies: antioxidation, anti-inflammation, calcium modulation, mitochondrial protection, ER stress inhibition, anti-apoptosis, ferroptosis inhibition, autophagy modulation, and inhibition of adverse cardiac remodeling. Additionally, the number and position of OH, 3'4'-catechol, C2=C3, and C4=O may play a significant role in the cardioprotective activity of flavonoids.

CONCLUSION

This review serves as a reference for designing a daily diet to prevent or reduce damages following ischemia and screening of flavonoids for clinical application.

ALKBH5-mediated m6A demethylation of pri-miR-199a-5p exacerbates myocardial ischemia/reperfusion injury by regulating TRAF3-mediated pyroptosis

Myocardial ischemia‒reperfusion injury (MI/RI) is closely related to pyroptosis. alkB homolog 5 (ALKBH5) is abnormally expressed in the MI/RI models. However, the detailed molecular mechanism of ALKBH5 in MI/RI has not been elucidated. In this study, rats and H9C2 cells served as experimental subjects and received MI/R induction and H/R induction, respectively. The abundance of the targeted molecules was evaluated using RT-qPCR, Western blotting, immunohistochemistry, immunofluorescence, and enzyme-linked immunosorbent assay. The heart functions of the rats were evaluated using echocardiography, and heart injury was evaluated. Cell viability and pyroptosis were determined using cell counting Kit-8 and flow cytometry, respectively. Total m6A modification was measured using a commercial kit, and pri-miR-199a-5p m6A modification was detected by Me-RNA immunoprecipitation (RIP) assay. The interactions among the molecules were validated using RIP and luciferase experiments. ALKBH5 was abnormally highly expressed in H/R-induced H9C2 cells and MI/RI rats. ALKBH5 silencing improved injury and inhibited pyroptosis. ALKBH5 reduced pri-miR-199a-5p m6A methylation to block miR-199a-5p maturation and inhibit its expression. TNF receptor-associated Factor 3 (TRAF3) is a downstream gene of miR-199a-5p. Furthermore, in H/R-induced H9C2 cells, the miR-199a-5p inhibitor-mediated promotion of pyroptosis was reversed by ALKBH5 silencing, and the TRAF3 overexpression-mediated promotion of pyroptosis was offset by miR-199a-5p upregulation. ALKBH5 silencing inhibited pri-miR-199a-5p expression and enhanced pri-miR-199a-5p m6A modification to promote miR-199a-5p maturation and enhance its expression, thereby suppressing pyroptosis to alleviate MI/RI through decreasing TRAF3 expression.

Unraveling the role of Xist RNA in cardiovascular pathogenesis

Understanding the molecular pathways behind cardiovascular illnesses is crucial due to the enormous worldwide health burden they impose. New insights into the role played by Xist (X-inactive specific transcript) RNA in the onset and progression of cardiovascular diseases have emerged from recent studies. Since its discovery, Xist RNA has been known for its role in X chromosome inactivation during embryogenesis; however, new data suggest that its function extends well beyond the control of sex chromosomes. The regulatory roles of Xist RNA are extensive, encompassing epigenetic changes, gene expression, cellular identity, and sex chromosomal inactivation. There is potential for the involvement of this complex regulatory web in a wide range of illnesses, including cardiovascular problems. Atherosclerosis, hypertrophy, and cardiac fibrosis are all conditions linked to dysregulation of Xist RNA expression. Alterations in DNA methylation and histones are two examples of epigenetic changes that Xist RNA orchestrates, leading to modifications in gene expression patterns in different cardiovascular cells. Additionally, Xist RNA has been shown to contribute to the development of cardiovascular illnesses by modulating endothelial dysfunction, inflammation, and oxidative stress responses. New treatment approaches may become feasible with a thorough understanding of the complex function of Xist RNA in cardiovascular diseases. By focusing on Xist RNA and the regulatory network with which it interacts, we may be able to slow the progression of atherosclerosis, cardiac hypertrophy, and fibrosis, thereby opening novel therapeutic options for cardiovascular diseases amenable to precision medicine. This review summarizes the current state of knowledge concerning the impact of Xist RNA in cardiovascular disorders.

LncRNA RNA ROR Aggravates Hypoxia/Reoxygenation-Induced Cardiomyocyte Ferroptosis by Targeting miR-769-5p/CBX7 Axis

Ferroptosis is a new way of cell death which is reported to participate in the pathology of myocardial ischemia-reperfusion (MI/R) injury, but it's mechanism remains unclear. The present investigation is to study the emerging role of long non-coding RNA (lncRNA) regulator of reprogramming (ROR) in cardiomyocyte ferroptosis after hypoxia/reoxygenation (H/R) administration. RT-qPCR and/or Western blot methods were performed to examine the gene/or protein levels, and CCK-8, ELISA, and DCFH-DA staining determined the cellular viability and ferroptosis. Dual-luciferase and RNA immunoprecipitation were applied to verify molecular interaction. LncRNA ROR and miR-769-5p were overexpressed and reduced in blood samples from MI patients and H/R-treated AC16 cells, respectively. Mechanistically, lncROR sponged to miR-769-5p, thus upregulating CBX7 expression. Functional experiments presented that lncRNA ROR silence mitigated H/R-stimulated inflammatory damage, oxidative stress, and ferroptosis in AC16 cells, whereas these roles could be reversed by co-downregulation of miR-769-5p or co-overexpression of CBX7. These data uncovered that lncRNA ROR prevented against H/R-induced cardiomyocyte ferroptosis by modulating miR-769-5p/CBX7 signaling, emphasizing the therapeutic value of lncRNA ROR in MI/R injury.

Neuronal MeCP2 in the dentate gyrus regulates mossy fiber sprouting of mice with temporal lobe epilepsy

Sprouting of mossy fibers, one of the most consistent findings in tissue from patients with mesial temporal lobe epilepsy, exhibits several uncommon axonal growth features and has been considered a paradigmatic example of circuit plasticity that occurs in the adult brain. Clarifying the mechanisms responsible may provide new insight into epileptogenesis as well as axon misguidance in the central nervous system. Methyl-CpG-binding protein 2 (MeCP2) binds to methylated genomic DNA to regulate a range of physiological functions implicated in neuronal development and adult synaptic plasticity. However, exploring the potential role of MeCP2 in the documented misguidance of axons in the dentate gyrus has not yet been attempted. In this study, a status epilepticus-induced decrease of neuronal MeCP2 was observed in the dentate gyrus (DG). An essential regulatory role of MeCP2 in the development of functional mossy fiber sprouting (MFS) was confirmed through stereotaxic injection of a recombinant adeno-associated virus (AAV) to up- or down-regulate MeCP2 in the dentate neurons. Chromatin immunoprecipitation sequencing (ChIP-seq) was performed to identify the binding profile of native MeCP2 using micro-dissected dentate tissues. In both dentate tissues and HT22 cell lines, we demonstrated that MeCP2 could act as a transcription repressor on miR-682 with the involvement of the DNA methylation mechanism. Further, we found that miR-682 could bind to mRNA of phosphatase and tensin homolog (PTEN) in a sequence specific manner, thus leading to the suppression of PTEN and excessive activation of mTOR. This study therefore presents a novel epigenetic mechanism by identifying MeCP2/miR-682/PTEN/mTOR as an essential signal pathway in regulating the formation of MFS in the temporal lobe epileptic (TLE) mice. SIGNIFICANCE STATEMENT: Understanding the mechanisms that regulate axon guidance is important for a better comprehension of neural disorders. Sprouting of mossy fibers, one of the most consistent findings in patients with mesial temporal lobe epilepsy, has been considered a paradigmatic example of circuit plasticity in the adult brain. Although abnormal regulation of DNA methylation has been observed in both experimental rodents and humans with epilepsy, the potential role of DNA methylation in this well-documented example of sprouting of dentate axon remains elusive. This study demonstrates an essential role of methyl-CpG-binding protein 2 in the formation of mossy fiber sprouting. The underlying signal pathway has been also identified. The data hence provide new insight into epileptogenesis as well as axon misguidance in the central nervous system.

CircUSP39/miR-362-3p/TRAF3 Axis Mediates Hypoxia/Reoxygenation-Induced Cardiomyocyte Oxidative Stress, Inflammation, and Apoptosis

Accumulating evidence suggested that aberrantly regulated circular RNA (circRNA) is a critical contributor to cardiovascular diseases, including acute myocardial infarction (AMI). However, the role and molecular mechanism of circUSP39 in AMI development remain unclear.Candidate circRNAs were screened from the Gene Expression Omnibus (GEO) database (GSE160717) and analyzed using the GEO2R tool. Hypoxia/reoxygenation (H/R) -induced AC16 cells were used to investigate the function of circUSP39 in H/R injury of cardiomyocytes. Quantitative real-time PCR (qRT-PCR) was employed to test RNA levels in H/R-induced AC16 cells. Cell Counting Kit-8, enzyme-linked immunosorbent assay, flow cytometry, and western blot (WB) assay were used to determine cell viability, oxidative stress, inflammatory factor levels, and cell apoptosis. RNA immunoprecipitation, RNA pull-down, and dual-luciferase reporter assay were conducted to validate the interactions between circRNA ubiquitin-specific peptidase 39 (circUSP39), miR-362-3p, and tumor necrosis factor receptor-associated factor 3 (TRAF3).In H/R-induced AC16 cells, the expression levels of circUSP39 and TRAF3 were upregulated whereas miR-362-3p expression was downregulated. CircUSP39 silencing markedly enhanced cell viability and superoxide dismutase activity but mitigated malondialdehyde level, secretion of inflammatory factors (IL-6, TNF-α, IL-1β, and MCP-1), and cell apoptosis in H/R-induced AC16 cells. CircUSP39 expedited H/R-induced AC16 cell injury by sponging miR-362-3p to increase the expression of TRAF3.CircUSP39 could facilitate H/R-induced cardiomyocyte oxidative stress, inflammation, and apoptosis by the miR-362-3p/TRAF3 axis, elucidating that it might be a therapeutic target for AMI.

Targeting Epigenetics and Non-coding RNAs in Myocardial Infarction: From Mechanisms to Therapeutics

Myocardial infarction (MI) is a complicated pathology triggered by numerous environmental and genetic factors. Understanding the effect of epigenetic regulation mechanisms on the cardiovascular disease would advance the field and promote prophylactic methods targeting epigenetic mechanisms. Genetic screening guides individualised MI therapies and surveillance. The present review reported the latest development on the epigenetic regulation of MI in terms of DNA methylation, histone modifications, and microRNA-dependent MI mechanisms and the novel therapies based on epigenetics.

LncRNA SOX2-OTinhibitionprotects against myocardialischemia/reperfusion-inducedinjury via themicroRNA-186-5p (miR-186-5p)/Yin Yang 1 (YY1)pathway

Long noncoding RNAs (lncRNAs) exert essential effects in regulating myocardial ischemia/reperfusion (MI/R)-induced injury. This work intended to explore the functions of lncRNA SOX2-OT and its regulatory mechanism within MI/R-induced injury. In this study, gene expression was determined by RT-qPCR. Western blotting was applied for the detection of protein levels. Pro-inflammatory cytokine concentrations, cardiomyocyte viability, and apoptosis were detected via ELISA, CCK-8 and flow cytometry. In the in vitro model, SOX2-OT and YY1 were both upregulated, while miR-186-5p was downregulated. SOX2-OT knockdown attenuated oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cardiomyocyte dysregulation through relieving inflammation, promoting proliferation, and reducing apoptosis in OGD/R-treated H2C9 cells. SOX2-OT positively regulated YY1 expression via miR-186-5p. Moreover, miR-186-5p inhibition or YY1 upregulation abolished the effects of SOX2-OT blocking on the inflammatory responses, proliferation, and apoptosis of OGD/R-challenged H2C9 cells. In conclusion, our results, for the first time, demonstrated that SOX2-OT inhibition attenuated MI/R injury in vitro via regulating the miR-186-5p/YY1 axis, offering potential therapeutic targets for MI/R injury treatment.

Knockdown of lncRNA Abhd11os attenuates myocardial ischemia/reperfusion injury by inhibiting apoptosis in cardiomyocytes

ABSTRACT

Long non-coding RNA (lncRNA) is one potential target for the treatment of various disorders. Here, we explored the role of Abhd11os in ischemia/reperfusion-induced myocardial injury, and preliminarily explored the regulatory mechanisms. Relative Abhd11os expression level was examined by qRT-PCR. Western blot was done to measure the expression of apoptotic-related proteins. CCK-8 assay and flow cytometry were performed to detect cell viability and apoptosis, respectively. ELISA assay was used to ensure the levels of LDH, CK, and cTnI in serum. Besides, the infarct sizes were confirmed by TTC and Evans blue staining. Apoptotic rate of cardiomyocytes in myocardial tissues was evaluated by TUNEL assay. Here, increased Abhd11os expression was found in rat myocardial ischemia/reperfusion injury (MIRI) model and hypoxia/reoxygenation (H/R)-treated cardiomyocytes. Subsequently, our data in vitro showed that upregulation of Abhd11os inhibited proliferation of cardiomyocytes, but promoted cell apoptosis. In animal experiments, myocardial infarct size in MIRI rats was reduced by Abhd11os knockdown. Moreover, downregulation of Abhd11os inhibited apoptosis of cardiomyocytes. Overall, our results revealed that knockdown of Abhd11os could notably attenuate H/R-induced myocardial injury through suppressing apoptosis of cardiomyocytes. These data suggest that Abhd11os may be a potential target for MIRI therapy.

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.

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.