Circ_0068655 Promotes Cardiomyocyte Apoptosis via miR-498/PAWR Axis

Circular RNA regulatory role in pathological cardiac remodelling

Cardiac remodelling involves structural, cellular and molecular alterations in the heart after injury, resulting in progressive loss of heart function and ultimately leading to heart failure. Circular RNAs (circRNAs) are a recently rediscovered class of non-coding RNAs that play regulatory roles in the pathogenesis of cardiovascular diseases, including heart failure. Thus, a more comprehensive understanding of the role of circRNAs in the processes governing cardiac remodelling may set the ground for the development of circRNA-based diagnostic and therapeutic strategies. In this review, the current knowledge about circRNA origin, conservation, characteristics and function is summarized. Bioinformatics and wet-lab methods used in circRNA research are discussed. The regulatory function of circRNAs in cardiac remodelling mechanisms such as cell death, cardiomyocyte hypertrophy, inflammation, fibrosis and metabolism is highlighted. Finally, key challenges and opportunities in circRNA research are discussed, and orientations for future work to address the pharmacological potential of circRNAs in heart failure are proposed.

Unraveling genomic diversity and positive selection signatures of Qaidam cattle through whole-genome re-sequencing

Qaidam cattle are a typical Chinese native breed inhabiting northwest China. They bear the characteristics of high cold and roughage tolerance, low-oxygen adaptability and good meat quality. To analyze the genetic diversity of Qaidam cattle, 60 samples were sequenced using whole-genome resequencing technology, along with 192 published sets of whole-genome sequencing data of Indian indicine cattle, Chinese indicine cattle, North Chinese cattle breeds, East Asian taurine cattle, Eurasian taurine cattle and European taurine cattle as controls. It was found that Qaidam cattle have rich genetic diversity in Bos taurus, but the degree of inbreeding is also high, which needs further protection. The phylogenetic analysis, principal component analysis and ancestral component analysis showed that Qaidam cattle mainly originated from East Asian taurine cattle. Qaidam cattle had a closer genetic relationship with the North Chinese cattle breeds and the least differentiation from Mongolian cattle. Annotating the selection signals obtained by composite likelihood ratio, nucleotide diversity analysis, integrated haplotype score, genetic differentiation index, genetic diversity ratio and cross-population extended haplotype homozygosity methods, several genes associated with immunity, reproduction, meat, milk, growth and adaptation showed strong selection signals. In general, this study provides genetic evidence for understanding the germplasm characteristics of Qaidam cattle. At the same time, it lays a foundation for the scientific and reasonable protection and utilization of genetic resources of Chinese local cattle breeds, which has great theoretical and practical significance.

Insights into circular RNAs : Biogenesis, function and their regulatory roles in cardiovascular disease

As a distinctive member of the noncoding RNA family, circular RNAs (circRNAs) are generated from single-stranded, covalently closed structures and are ubiquitous in mammalian cells and tissues. Due to its atypical circular architecture, it was conventionally deemed insignificant dark matter for a prolonged duration. Nevertheless, studies conducted over the last decade have demonstrated that this abundant, structurally stable and tissue-specific RNA has been increasingly relevant in diverse diseases, including cancer, neurological disorders, diabetes mellitus and cardiovascular diseases (CVDs). Therefore, regulatory pathways controlled by circRNAs are widely involved in the occurrence and pathological processes of CVDs through their function as miRNA sponges, protein sponges and protein scaffolds. To better understand the role of circRNAs and their complex regulatory networks in CVDs, we summarize current knowledge of their biogenesis and function and the latest research on circRNAs in CVDs, with the hope of paving the way for the identification of promising biomarkers and therapeutic strategies for CVDs.

Circular RNAs: Biogenesis, Biological Functions, and Roles in Myocardial Infarction

Non-coding RNAs have been excavated as important cardiac function modulators and linked to heart diseases. Significant advances have been obtained in illuminating the effects of microRNAs and long non-coding RNAs. Nevertheless, the characteristics of circular RNAs are rarely mined. Circular RNAs (circRNAs) are widely believed to participate in cardiac pathologic processes, especially in myocardial infarction. In this review, we round up the biogenesis of circRNAs, briefly describe their biological functions, and summarize the latest literature on multifarious circRNAs related to new therapies and biomarkers for myocardial infarction.

The role of circular RNAs in pulmonary hypertension

Circular RNAs (circRNAs) are endogenous, covalently circularised, non-protein-coding RNAs generated from back-splicing. Most circRNAs are very stable, highly conserved, and expressed in a tissue-, cell- and developmental stage-specific manner. circRNAs play a significant role in various biological processes, such as regulation of gene expression and protein translation via sponging of microRNAs and binding with RNA-binding proteins. circRNAs have become a topic of great interest in research due to their close link with the development of various diseases. Their high stability, conservation and abundance in body fluids make them promising biomarkers for many diseases. A growing body of evidence suggests that aberrant expression of circRNAs and their targets plays a crucial role in pulmonary vascular remodelling and pulmonary arterial hypertension (group 1) as well as other forms (groups 3 and 4) of pulmonary hypertension (PH). Here we discuss the roles and molecular mechanisms of circRNAs in the pathogenesis of pulmonary vascular remodelling and PH. We also highlight the therapeutic and biomarker potential of circRNAs in PH.

miR-1183 Is a Key Marker of Remodeling upon Stretch and Tachycardia in Human Myocardium

Many cardiac insults causing atrial remodeling are linked to either stretch or tachycardia, but a comparative characterization of their effects on early remodeling events in human myocardium is lacking. Here, we applied isometric stretch or sustained tachycardia at 2.5 Hz in human atrial trabeculae for 6 h followed by microarray gene expression profiling. Among largely independent expression patterns, we found a small common fraction with the microRNA miR-1183 as the highest up-regulated transcript (up to 4-fold). Both, acute stretch and tachycardia induced down-regulation of the predicted miR-1183 target genes ADAM20 and PLA2G7. Furthermore, miR-1183 was also significantly up-regulated in chronically remodeled atrial samples from patients with persistent atrial fibrillation (3-fold up-regulation versus sinus rhythm samples), and in ventricular myocardium from dilative cardiomyopathy hearts (2-fold up-regulation) as compared to non-failing controls. In sum, although stretch and tachycardia show distinct transcriptomic signatures in human atrial myocardium, both cardiac insults consistently regulate the expression of miR-1183 and its downstream targets in acute and chronic remodeling. Thus, elevated expression of miR-1183 might serve as a tissue biomarker for atrial remodeling and might be of potential functional significance in cardiac disease.

CircTRRAP Knockdown Has Cardioprotective Function in Cardiomyocytes via the Signal Regulation of miR-370-3p/PAWR Axis

Background

Circular RNA Transformation/Transcription Domain Associated Protein (circTRRAP, hsa_circ_0081241) was abnormally upregulated in acute myocardial infarction (AMI) patients. However, its biological role and functional mechanism in AMI remain to be researched.

Methods

Human cardiomyocyte AC16 was exposed to hypoxia to induce cell injury. Cell viability was detected through Cell Counting Kit-8. CircTRRAP, microRNA-370-3p (miR-370-3p), and Pro-Apoptotic WT1 Regulator (PAWR) levels were assayed by reverse transcription-quantitative polymerase chain reaction. Cell proliferation analysis was performed via 5-ethynyl-2′-deoxyuridine (EdU) assay. Cell apoptosis was assessed using flow cytometry and caspase-3 activity assay. The protein levels were measured through western blot. Enzyme-linked immunosorbent assay was used to examine the release of inflammatory cytokines. Oxidative stress was assessed by the commercial kits. Dual-luciferase reporter assay, RNA immunoprecipitation, and RNA pull-down assays were performed for the validation of target interaction.

Results

CircTRRAP was highly expressed following hypoxia treatment in AC16 cells. Downregulation of circTRRAP promoted cell growth but inhibited apoptosis, inflammation, and oxidative stress in hypoxic cells. CircTRRAP could target miR-370-3p, and the regulatory effects of circTRRAP on the hypoxic cells were associated with the sponge function of miR-370-3p. PAWR served as the target for miR-370-3p, and it was regulated by circTRRAP/miR-370-3p axis. The protective role of miR-370-3p was achieved by downregulating the PAWR expression in hypoxia-treated AC16 cells.

Conclusion

These findings demonstrated that silence of circTRRAP exerted the protection against the hypoxia-induced damages in cardiomyocytes through regulating the miR-370-3p and PAWR levels.

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.

Emerging roles of circRNAs in the pathological process of myocardial infarction

Myocardial infarction (MI) is defined as cardiomyocyte death in a clinical context consistent with ischemic insult. MI remains one of the leading causes of morbidity and mortality worldwide. Although there are a number of effective clinical methods for the diagnosis and treatment of MI, further investigation of novel biomarkers and molecular therapeutic targets is required. Circular RNAs (circRNAs), novel non-coding RNAs, have been reported to function mainly by acting as microRNA (miRNA) sponges or binding to RNA-binding proteins (RBPs). The circRNA-miRNA-mRNA (protein) regulatory pathway regulates gene expression and affects the pathological mechanisms of various diseases. Undoubtedly, a more comprehensive understanding of the relationship between MI and circRNA will lay the foundation for the development of circRNA-based diagnostic and therapeutic strategies for MI. Therefore, this review summarizes the pathophysiological process of MI and various approaches to measure circRNA levels in MI patients, tissues, and cells; highlights the significance of circRNAs in the regulation MI pathogenesis and development; and provides potential clinical insight for the diagnosis, prognosis, and treatment of MI.

Local delivery of a senolytic drug in ischemia and reperfusion-injured heart attenuates cardiac remodeling and restores impaired cardiac function

Myocardial ischemia-reperfusion (IR) generates stress-induced senescent cells (SISCs) that play an important role in the pathophysiology of adverse cardiac remodeling and heart failure via secretion of pro-inflammatory molecules and matrix-degrading proteases. Thus, removal of senescent cells using a senolytic drug could be a potentially effective treatment. However, clinical studies on cancer treatment with a senolytic drug have revealed that systemic administration of a senolytic drug often causes systemic toxicity. Herein we show for the first time that local delivery of a senolytic drug can effectively treat myocardial IR injury. We found that biodegradable poly(lactic-co-glycolic acid) nanoparticle-based local delivery of a senolytic drug (ABT263-PLGA) successfully eliminated SISCs in the IR-injured rat hearts without systemic toxicity. Consequently, the treatment ameliorated inflammatory responses and attenuated adverse remodeling. Surprisingly, the ABT263-PLGA treatment restored the cardiac function over time, whereas the cardiac function decreased over time in the no treatment group. Mechanistically, the ABT263-PLGA treatment not only markedly reduced the expression of pro-inflammatory molecules and matrix-degrading proteases, but also induced macrophage polarization from the inflammatory phase to the reparative phase via efferocytosis of apoptotic SISCs by macrophages. Therefore, the senolytic strategy with ABT263-PLGA in the early stage of myocardial IR injury may be an effective therapeutic option for myocardial infarction. STATEMENT OF SIGNIFICANCE: This study describes a local injection of senolytic drug-loaded nanoparticles that selectively kills stress-induced senescent cells (SISCs) in infarcted heart. Removal of SISCs decreases inflammatory cytokines and normal cell death. We firstly revealed that further efferocytosis of apoptotic senescent cells by macrophages restores cardiac function after myocardial ischemia-reperfusion injury. Importantly, a local injection of senolytic drug did not exhibit systemic toxicity, but a systemic injection did. Our findings not only spotlight the basic understanding of therapeutic potential of senolysis in infarcted myocardium, but also pave the way for the further application of senolytic drug for non-aging related diseases.

Knockdown of MIR9‑3HG inhibits proliferation and promotes apoptosis of cervical cancer cells by miR‑498 via EP300

Cervical cancer is a serious gynecological cancer and one of the primary causes of mortality in female patients with cancer. Despite advances in cancer research, the molecular mechanism underlying cancer remains poorly understood. High levels of MIR9-3 host gene (HG) are associated with the occurrence and development of cervical cancer. However, the specific role of MIR9-3HG during the development of cervical cancer is unclear. In the present study, the expression of MIR9-3HG was silenced in C33A and SiHa cervical cancer cell lines. Proliferation and apoptosis were measured in these cells using 5-ethynyl-2′-deoxyuridine assay and flow cytometry, respectively. In addition, targeting microRNAs (miRs) of MIR9-3HG and mRNAs of miR-498 were predicted using public databases. The predicted interactions between these molecules were validated using RNA immunoprecipitation, RNA pull-down and luciferase reporter assays. Lastly, C33A cells transfected with short hairpin MIR-3HG alone or in combination with miR-498 inhibitor or PC-EP300 were subcutaneously injected into mice. The levels of miR-498, EP300 and Ki67 in tumor tissue were measured via reverse transcription-quantitative PCR or western blotting. MIR9-3HG knockdown inhibited the proliferation of cervical cancer cells, whilst promoting apoptosis. MIR9-3HG sponged miR-498 and inhibited its expression. Additionally, miR-498 interacted with EP300 and inhibited its expression. Transfection with miR-498 inhibitor significantly decreased apoptosis levels; this effect was abolished following EP300 silencing in vitro. In vivo, both miR-498 inhibition and EP300 overexpression reversed the inhibition of tumor growth mediated by MIR-3HG knockdown. MIR9-3HG promoted the proliferation cervical cancer cells via EP300 and miR-498. These in vitro and in vivo findings demonstrate the regulatory role of the MIR9-3HG/miR-498/EP300 axis in cervical cancer cell growth. Thus, the present study identified novel molecular targets for the diagnosis and treatment of cervical cancer and provided new insight into the pathogenesis of cervical cancer.

CircJARID2 Regulates Hypoxia-Induced Injury in H9c2 Cells by Affecting miR-9-5p-Mediated BNIP3

ABSTRACT

Myocardial infarction (MI) is a common cardiovascular disease, and many circular RNAs (circRNAs) have been found to participate in the pathological process. This study was to research circRNA jumonji and AT-rich interaction domain containing 2 (circJARID2) in MI. MI cell model was established by hypoxia treatment in H9c2 cells. CircJARID2 and microRNA-9-5p (miR-9-5p) levels were examined using real-time polymerase chain reaction. Cell viability detection was performed by Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (Edu) assays. Cell apoptosis was evaluated by flow cytometry and caspase-3 activity assay. Apoptotic markers and B-cell lymphoma-2 (Bcl-2) interacting protein 3 (BNIP3) were quantified by western blot. Inflammatory cytokines were determined via enzyme-linked immunosorbent assay. The genic interaction was analyzed through dual-luciferase reporter and RNA immunoprecipitation assays. Hypoxia induced the upregulation of circJARID2 expression in H9c2 cells. The hypoxia-induced cell viability inhibition, apoptosis promotion, and inflammatory response were all counterbalanced by knockdown of circJARID2. CircJARID2 interacted with miR-9-5p, and its function in regulating the hypoxia-induced cell injury was also dependent on targeting miR-9-5p. BNIP3 acted as a target gene of miR-9-5p, and circJARID2 had positive effect on BNIP3 expression by binding to miR-9-5p. MiR-9-5p played a protective role for H9c2 cells against the hypoxia-induced injury via targeting BNIP3. CircJARID2 overexpression contributed to the hypoxia-induced H9c2 cell injury by sponging miR-9-5p to upregulate BNIP3 expression, showing a novel molecular network of MI pathomechanism.

Myocardial Infarction: The Protective Role of MiRNAs in Myocardium Pathology

Cardiovascular diseases have been regarded as the leading cause of death around the world, with myocardial infarction (MI) being the most severe form. MI leads to myocardial apoptosis, cardiomyocyte fibrosis, and cardiomyocyte hypertrophy, ultimately leading to heart failure, and death. Micro RNAs (miRNAs) participate in the genesis and progression of myocardial pathology after MI by playing an important regulatory role. This review aims to summarize all available knowledge on the role of miRNAs in the myocardial pathological process after MI to uncover potential major target pathways. In addition, the main therapeutic methods and their latest progress are also reviewed. miRNAs can regulate the main signaling pathways as well as pathological processes. Thus, they have the potential to induce therapeutic effects. Hence, the combination of miRNAs with recently developed exosome nanocomplexes may represent the future direction of therapeutics.

Circular RNA POSTN Promotes Myocardial Infarction-Induced Myocardial Injury and Cardiac Remodeling by Regulating miR-96-5p/BNIP3 Axis

Myocardial infarction (MI) is the most prevalent cardiac disease with high mortality, leading to severe heart injury. Circular RNAs (circRNAs) are a new type of regulatory RNAs and participate in multiple pathological cardiac progressions. However, the role of circRNAs Postn (circPostn) in MI modulation remains unclear. Here, we aimed to explore the effect of circPostn on MI-induced myocardial injury and cardiac remodeling. We identified that the expression of circPostn was elevated in the plasma of MI patients, MI mouse model, and hypoxia and reoxygenation (H/R)-treated human cardiomyocytes. The depletion of circPostn significantly attenuated MI-related myocardium injury and reduced the infarct size in MI mouse model. The circPostn knockdown obviously enhanced left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS) and inhibited left ventricular anterior wall thickness at diastole (LVAWd) and left ventricular posterior wall thickness at diastole (LVPWd). The depletion of circPostn was able to decrease MI-induced expression of collagen 1α1 and collagen 3α1 in the ventricular tissues of mice. The protein expression of collagen and α-smooth muscle actin (SMA) was up-regulated in MI mice and was inhibited by circPostn knockdown. Meanwhile, the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) was repressed by circPostn depletion in the ventricular tissues of MI mice. Besides, the circPostn depletion attenuated cardiomyocyte apoptosis in mice. Mechanically, circPostn served as a miR-96-5p sponge and miR-96-5p-targeted BNIP3 in human cardiomyocytes, in which circPostn up-regulated BNIP3 expression by targeting miR-96-5p. circPostn promoted H/R-induced cardiomyocyte injury by modulating miR-96-5p/BNIP3 axis. Thus, we conclude that circPostn contributes to MI-induced myocardial injury and cardiac remodeling by regulating miR-96-5p/BNIP3 axis. Our finding provides new insight into the mechanism by which circPostn regulates MI-related cardiac dysfunction. circPostn, miR-96-5p, and BNIP3 are potential targets for the treatment of MI-caused heart injury.