A circular RNA, circUSP36, accelerates endothelial cell dysfunction in atherosclerosis by adsorbing miR-637 to enhance WNT4 expression

Circ_0005699 Expedites ox-LDL-Triggered Endothelial Cell Injury via Targeting miR-384/ASPH Axis

Atherosclerosis (AS) is an inflammatory disease with multiple causes. Multiple circular RNAs (circRNAs) are known to be involved in the pathogenesis of AS. To explore the function and mechanism of circ_0005699 in oxidative low-density lipoprotein (ox-LDL)-induced human umbilical vein endothelial cells (HUVECs) injury. Ox-LDL treatment restrained HUVECs viability, cell proliferation, and angiogenesis ability, and accelerated HUVECs apoptosis, inflammatory response, and oxidative stress. Circ_0005699 was up-regulated in the serum samples of AS patients and ox-LDL-induced HUVECs. Interference of circ_0005699 effectively rescued ox-LDL-induced injury in HUVECs. Additionally, miR-384 could bind to circ_0005699, and miR-384 depletion inverted the effects of circ_0005699 deficiency on ox-LDL-mediated HUVEC injury. Moreover, ASPH was a direct target of miR-384, and the enforced expression of ASPH overturned miR-384-induced effects on ox-LDL-induced HUVECs. Importantly, circ_0005699 regulated ASPH expression via sponging miR-384. Interference of circ_0005699 protected against ox-LDL-induced injury in HUVECs at least partly by regulating ASPH expression via acting as a miR-384 sponge.

Circular RNA: A new expectation for cardiovascular diseases

Circular RNA (circRNA) is a class of RNA with the 5' and 3' ends connected covalently to form a closed loop structure and characterized by high stability, conserved sequences and tissue specificity, which is caused by special reverse splicing methods. Currently, it has become a hot spot for research. With the discovery of its powerful regulatory functions and roles, the molecular mechanisms and future value of circRNA in participating in and regulating biological and pathological processes are becoming increasingly apparent. Among them is the increasing prevalence of cardiovascular diseases (CVDs). Many studies have elucidated that circRNA plays a crucial role in the development and progression of CVDs. Therefore, circRNA shows its advantages and brilliant expectations in the field of CVDs. In this review, we describe the biogenesis, bioinformatics detection and function of circRNA and discuss the role of circRNA and its effects on CVDs, including atherosclerosis, myocardial infarction, cardiac hypertrophy and heart failure, myocardial fibrosis, cardiac senescence, pulmonary hypertension, and diabetic cardiomyopathy by different mechanisms. That shows circRNA advantages and brilliant expectations in the field of CVDs.

CircLZIC regulates ox-LDL-induced HUVEC cell proliferation and apoptosis via Micro-330-5p/NOTCH2 axis in atherosclerosis

Atherosclerosis (AS) is a major chronic non-communicable disease and a primary cause of cardiovascular disease. Recent studies have shown that circRNAs are potential epigenetic factors that regulate vascular endothelial inflammatory responses and AS progression. Therefore, identification of the circRNAs that regulate ox-LDL levels is a critical step to understanding the pathology of AS. Our study is aim to investigate how circLZIC regulates atherosclerosis (AS) via the Micro-330-5p/NOTCH2 regulatory axis. The results showed that CircLZIC and NOTCH2 are highly expressed in human AS clinical samples, while Micro-330-5p is expressed locally. The CCK-8 experiment results showed that circLZIC promotes the proliferation of HUVECS cells. Flow cytometry analysis showed that circLZIC act as an inhibitor of HUVEC cell apoptosis. The expression level of Micro-330-5p can be up-regulated by transfection of small interfering RNA against circLZIC. Further, Starbase predicted that Micro-330-5p could target and regulate NOTCH2. Next, we confirmed that overexpression of Micro-330-5p could significantly reduce the expression of fluorescein using the double Luciferase reporter assay. RIP-qRT-PCR experiment showed that Micro-330-5p and NOTCH2 mRNAs are effectively enriched by ago2 protein. Further, we found that knocking down circLZIC increases the expression of Micro-330-5p and promotes cell apoptosis, while inhibiting the expression of NOTCH2 and cell activity. On the other hand, co-transfection of Micro-330-5p inhibitor decreases Micro-330-5p expression and inhibit cell apoptosis, while increasing NOTCH2 expression and cell activity. In conclusion, CircLZIC regulates HUVEC cell activity by the Micro-330-5p/NOTCH2 signaling pathway, suggesting that circLZIC plays a key role in atherosclerosis development.

MiRNA-21a, miRNA-145, and miRNA-221 Expression and Their Correlations with WNT Proteins in Patients with Obstructive and Non-Obstructive Coronary Artery Disease

MicroRNAs and the WNT signaling cascade regulate the pathogenetic mechanisms of atherosclerotic coronary artery disease (CAD) development.

OBJECTIVE

To evaluate the expression of microRNAs (miR-21a, miR-145, and miR-221) and the role of the WNT signaling cascade (WNT1, WNT3a, WNT4, and WNT5a) in obstructive CAD and ischemia with no obstructive coronary arteries (INOCA).

METHOD

The cross-sectional observational study comprised 94 subjects. The expression of miR-21a, miR-145, miR-221 (RT-PCR) and the protein levels of WNT1, WNT3a, WNT4, WNT5a, LRP6, and SIRT1 (ELISA) were estimated in the plasma of 20 patients with INOCA (66.5 [62.8; 71.2] years; 25% men), 44 patients with obstructive CAD (64.0 [56.5; 71,0] years; 63.6% men), and 30 healthy volunteers without risk factors for cardiovascular diseases (CVD).

RESULTS

Higher levels of WNT1 (0.189 [0.184; 0.193] ng/mL vs. 0.15 [0.15-0.16] ng/mL, p < 0.001) and WNT3a (0.227 [0.181; 0.252] vs. 0.115 [0.07; 0.16] p < 0.001) were found in plasma samples from patients with obstructive CAD, whereas the INOCA group was characterized by higher concentrations of WNT4 (0.345 [0.278; 0.492] ng/mL vs. 0.203 [0.112; 0.378] ng/mL, p = 0.025) and WNT5a (0.17 [0.16; 0.17] ng/mL vs. 0.01 [0.007; 0.018] ng/mL, p < 0.001). MiR-221 expression level was higher in all CAD groups compared to the control group (p < 0.001), whereas miR-21a was more highly expressed in the control group than in the obstructive (p = 0.012) and INOCA (p = 0.003) groups. Correlation analysis revealed associations of miR-21a expression with WNT1 (r = -0.32; p = 0.028) and SIRT1 (r = 0.399; p = 0.005) protein levels in all CAD groups. A positive correlation between miR-145 expression and the WNT4 protein level was observed in patients with obstructive CAD (r = 0.436; p = 0.016). Based on multivariate regression analysis, a mathematical model was constructed that predicts the type of coronary lesion. WNT3a and LRP6 were the independent predictors of INOCA (p < 0.001 and p = 0.002, respectively).

CONCLUSIONS

Activation of the canonical cascade of WNT-β-catenin prevailed in patients with obstructive CAD, whereas in the INOCA and control groups, the activity of the non-canonical pathway was higher. It can be assumed that miR-21a has a negative effect on the formation of atherosclerotic CAD. Alternatively, miR-145 could be involved in the development of coronary artery obstruction, presumably through the regulation of the WNT4 protein. A mathematical model with WNT3a and LRP6 as predictors allows for the prediction of the type of coronary artery lesion.

Exosomal circ-0020887 and circ-0009590 as novel biomarkers for the diagnosis and prediction of short-term adverse cardiovascular outcomes in STEMI patients

This study attempted to identify exosomal circular RNAs (circRNAs) as diagnostic and prognostic biomarkers for patients with ST-segment elevation myocardial infarction (STEMI). The differentially expressed exosomal circRNAs (DEECs) were screened from microarray dataset (GSE160717 and GSE197137) and RNA-Seq dataset (GSE208194), and the expression levels of DEECs in patients with STEMI were validated using reverse transcription and quantitative real-time PCR. The diagnostic value of DEECs was assessed using receiver operating characteristic curves. The major adverse cardiovascular event (MACE)-free 1-year survival rate was evaluated using the Kaplan-Meier method, and the factors affecting prognosis were determined using Cox regression model analysis. Results showed that four DEECs were screened including exo-circ-0001490, exo-circ-0020887, exo-circ-0009590, and exo-circ-0055440, and only upregulated exo-circ-0020887 and exo-circ-0009590 expression was validated in patients with STEMI. The exo-circ-0020887 and exo-circ-0009590 expression was positively correlated with hs-CRP, LDL-C, cTnI, and CK-MB. The exo-circ-0020887 and exo-circ-0009590 showed good diagnostic efficacy to distinguish STEMI patients from healthy controls (area under the curves: 0.85 and 0.80). STEMI patients with high levels of exo-circ-0020887 and exo-circ-0009590 had lower MACE-free 1-year survival rate, and exo-circ-0020887 and exo-circ-0009590 expression was independent risk factors for adverse prognosis. In summary, upregulation of plasma exo-circ-0020887 and exo-circ-0009590 might act as potential biomarkers for the diagnosis and prediction of short-term adverse cardiovascular outcomes in patients with STEMI.

Role of Circular RNAs in Atherosclerosis through Regulation of Inflammation, Cell Proliferation, Migration, and Apoptosis: Focus on Atherosclerotic Cerebrovascular Disease

Atherosclerosis (AS) is a disease dangerous to human health and the main pathological cause of ischemic cardiovascular diseases. Although its pathogenesis is not fully understood, numerous basic and clinical studies have shown that AS is a chronic inflammatory disease existing in all stages of atherogenesis. It may be a common link or pathway in the pathogenesis of multiple atherogenic factors. Inflammation is associated with AS complications, such as plaque rupture and ischemic cerebral infarction. In addition to inflammation, apoptosis plays an important role in AS. Apoptosis is a type of programmed cell death, and different apoptotic cells have different or even opposite roles in the process of AS. Unlike linear RNA, circular RNA (circRNA) a covalently closed circular non-coding RNA, is stable and can sponge miRNA, which can affect the stages of AS by regulating downstream pathways. Ultimately, circRNAs play very important roles in AS by regulating inflammation, apoptosis, and some other mechanisms. The study of circular RNAs can provide new ideas for the prediction, prevention, and treatment of AS.

Circular RNA as Therapeutic Targets in Atherosclerosis: Are We Running in Circles?

Much attention has been paid lately to harnessing the diagnostic and therapeutic potential of non-coding circular ribonucleic acids (circRNAs) and micro-RNAs (miRNAs) for the prevention and treatment of cardiovascular diseases. The genetic environment that contributes to atherosclerosis pathophysiology is immensely complex. Any potential therapeutic application of circRNAs must be assessed for risks, benefits, and off-target effects in both the short and long term. A search of the online PubMed database for publications related to circRNA and atherosclerosis from 2016 to 2022 was conducted. These studies were reviewed for their design, including methods for developing atherosclerosis and the effects of the corresponding atherosclerotic environment on circRNA expression. Investigated mechanisms were recorded, including associated miRNA, genes, and ultimate effects on cell mechanics, and inflammatory markers. The most investigated circRNAs were then further analyzed for redundant, disparate, and/or contradictory findings. Many disparate, opposing, and contradictory effects were observed across experiments. These include levels of the expression of a particular circRNA in atherosclerotic environments, attempted ascertainment of the in toto effects of circRNA or miRNA silencing on atherosclerosis progression, and off-target, cell-specific, and disease-specific effects. The high potential for detrimental and unpredictable off-target effects downstream of circRNA manipulation will likely render the practice of therapeutic targeting of circRNA or miRNA molecules not only complicated but perilous.

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.

CircRnas in atherosclerosis, with special emphasis on the spongy effect of circRnas on miRnas

Atherosclerosis (AS) is a chronic inflammatory disease, which leads to atherosclerotic rupture, lumen stenosis and thrombosis, and often endangers life. Circular RNAs (circRNAs) are a special class of non-coding RNA molecules, whose abnormal expression has been proved to be closely related to human diseases, including AS. Both the abnormal regulation of circRNAs and the sponging effect on miRNAs would lead to changes in gene expression in the form of epigenetic modification, ultimately leading to the formation of AS. CircRNAs can be used as peripheral blood markers of AS, and play an important regulatory role in the proliferation, migration, inflammation and apoptosis of vascular smooth muscle cells, endothelial cells and macrophage, which are key cells for the development of AS. The in-depth understanding of circRNAs in AS not only provides a new method for the diagnosis of AS, but also provides a new idea for the treatment of AS.

Potential roles of endothelial cells-related non-coding RNAs in cardiovascular diseases

Endothelial dysfunction is identified by a conversion of the endothelium toward decreased vasodilation and prothrombic features and is known as a primary pathogenic incident in cardiovascular diseases. An insight based on particular and promising biomarkers of endothelial dysfunction may possess vital clinical significances. Currently, non-coding RNAs due to their participation in critical cardiovascular processes like initiation and progression have gained much attention as possible diagnostic as well as prognostic biomarkers in cardiovascular diseases. Emerging line of proof has demonstrated that abnormal expression of non-coding RNAs is nearly correlated with the pathogenesis of cardiovascular diseases. In the present review, we focus on the expression and functional effects of various kinds of non-coding RNAs in cardiovascular diseases and negotiate their possible clinical implications as diagnostic or prognostic biomarkers and curative targets.

Circ_0033596 depletion ameliorates oxidized low-density lipoprotein-induced human umbilical vein endothelial cell damage

BACKGROUND

Previous data have shown that circ_0033596 is involved in the pathogenesis of atherosclerosis (AS). The study aims to reveal the detailed mechanism of circ_0033596 in AS.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to establish an AS cell model. Quantitative real-time polymerase chain reaction and western blot were implemented to detect the expression of circ_0033596, miR-637, growth factor receptor bound protein2 (GRB2), BCL2-associated x protein (Bax) and B-cell lymphoma-2 (Bcl-2). Cell viability, proliferation, apoptosis and tube formation were investigated by cell counting kit-8, EdU assay, flow cytometry and tube formation assay, respectively. The production of interleukin (IL-6) and tumor necrosis factor-α (TNF-α) was evaluated by enzyme-linked immunosorbent assay. Oxidative stress was evaluated by lipid peroxidation malondialdehyde assay kit and superoxide dismutase activity assay kit. Dual-luciferase reporter assay, RNA pull-down assay and RIP assay were performed to identify the associations among circ_0033596, miR-637 and GRB2.

RESULTS

The expression of circ_0033596 and GRB2 was significantly increased, while miR-637 was decreased in the blood of AS patients and ox-LDL-induced HUVECs compared with controls. Ox-LDL treatment inhibited HUVEC viability, proliferation and angiogenic ability and induced cell apoptosis, inflammation and oxidative stress, while these effects were attenuated after circ_0033596 knockdown. Circ_0033596 interacted with miR-637 and regulated ox-LDL-induced HUVEC damage by targeting miR-637. In addition, GRB2, a target gene of miR-637, participated in ox-LDL-induced HUVEC injury by combining with miR-637. Importantly, circ_0033596 activated GRB2 by interacting with miR-637.

CONCLUSION

Circ_0033596 depletion protected against ox-LDL-induced HUVEC injury by miR-637/GRB2 pathway, providing a therapeutic target for AS.

Circular RNA circ_0029589 promotes ox-LDL-induced endothelial cell injury through regulating RAB22A by serving as a sponge of miR-1197

BACKGROUND

Dysfunction of endothelial cells is now considered a vital contributor to the pathogenesis of atherosclerosis (AS). Moreover, circular RNA (circRNA) circ_0029589 has been found to be involved in the regulation of oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell damage. Nevertheless, its molecular mechanism in ox-LDL-triggered endothelial cell injury is poorly defined.

METHODS

Human umbilical vein endothelial cells (HUVECs) treated with ox-LDL were applied as cell models of AS. Circ_0029589, microRNA-1197 (miR-1197), and Ras-related protein Rab-22A (RAB22A) expression were detected using real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation, apoptosis, angiogenesis, and invasion were detected using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, tube formation, and transwell assays. Western blot analysis of Cleaved-caspase-3, B-cell lymphoma-2 related X protein (Bax), and RAB22A. IL-6, IL-1β, and Tumor necrosis factor α (TNF-α) levels were gauged using ELISA kits. Superoxide Dismutase (SOD) activity and Malondiahyde (MDA) level were assessed using special kits. Bioinformatics software predicted the binding between miR-1197 and circ_0029589 or RAB22A, which was proved using dual-luciferase reporter and RNA pull-down assays.

RESULTS

Circ_0029589 and RAB22A expression were strengthened, and miR-1197 was reduced in ox-LDL-treated HUVECs. Importantly, circ_0029589 silencing ameliorated ox-LDL-triggered HUVEC damage via promoting cell proliferation, tube formation ability, invasion, and repressing cell apoptosis, inflammation, and oxidative stress. Mechanical analysis suggested that circ_0029589 might affect RAB22A content through sponging miR-1197.

CONCLUSION

Circ_0090231 might protect against ox-LDL-mediated HUVEC injury via the miR-1197/RAB22A axis, which provides a therapeutic strategy for endothelial cell damage of AS.

CircIRAK1 aggravates ox-LDL-induced endothelial cell injury in atherosclerosis via TRIM14 upregulation by binding to miR-330-5p

BACKGROUND

Atherosclerosis (AS) is a common inflammatory cardiovascular disease, and circular RNAs (circRNAs) are associated with the pathogenesis of AS. CircRNA Interleukin (IL)-1 receptor-associated kinase 1 (circIRAK1, hsa_circ_0091822) was upregulated in AS. The aims of this study were to ascertain the function and mechanism of circIRAK1 in AS.

METHODS

Human Umbilical Vein Endothelial Cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL). RNA expression was detected by reverse transcription-quantitative polymerase chain reaction assay. Cell viability was examined using Cell Counting Kit-8 assay. Tube formation ability was measured by tube formation assay. Cell apoptosis was assessed using flow cytometry. Western blot was used for protein detection. Inflammatory reaction was evaluated via Enzyme-linked immunosorbent assay. Oxidative injury was analyzed by commercial kits. Target binding was determined through dual-luciferase reporter assay, RNA immunoprecipitation assay and pull-down assay.

RESULTS

The expression of circIRAK1 was upregulated in AS serums and ox-LDL-treated HUVECs. Silencing circIRAK1 enhanced cell viability and angiogenesis while suppressed cell apoptosis, inflammatory response and oxidative stress in ox-LDL-stimulated HUVECs. CircIRAK1 served as a molecular sponge for miR-330-5p. CircIRAK1 regulated ox-LDL-mediated cell injury by absorbing miR-330-5p. In addition, miR-330-5p prevented endothelial cell dysfunction caused by ox-LDL via targeting tripartite motif containing 14 (TRIM14). TRIM14 expression was upregulated by circIRAK1 through sponging miR-330-5p.

CONCLUSION

These results suggested that circIRAK1 upregulated TRIM14 by interacting with miR-330-5p, consequently contributing to ox-LDL-induced endothelial cell injury in AS.

Circ_0003575 knockdown alleviates ox-LDL-induced human aortic endothelial cell dysfunction in atherosclerosis by miR-637/TRAF6 axis

BACKGROUND

Circular RNAs (circRNAs) are involved in the progression of atherosclerosis (AS). The present study aimed to determine the functions and mechanism of circ_0003575 in AS.

METHODS

Oxidized low-density lipoprotein (ox-LDL) was used to induce human aortic endothelial cells (HAECs) to establish an AS cell model. Cell Counting Kit-8 (CCK-8) assay and 5'-ethynyl-2'-deoxyuridine (EdU) assay were conducted to assess cell proliferation. Flow cytometry analysis was utilized to quantify cell apoptosis. Tube formation assay was performed to analyze angiogenesis ability. Enzyme linked immunosorbent assay (ELISA) was used to examine the concentrations of inflammatory factors. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were manipulated for the expression of circ_0003575, microRNA-637 (miR-637) and TNF receptor associated factor 6 (TRAF6). Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were adopted to estimate the downstream targets of circ_0003575.

RESULTS

Ox-LDL treatment repressed the proliferation and angiogenesis and promoted the apoptosis and inflammation in HAECs. Circ_0003575 knockdown ameliorated ox-LDL-induced injury of HAECs. Circ_0003575 interacted with mi-R-637, which directly targeted TRAF6. Inhibition of miR-637 reversed the impacts of circ_0003575 knockdown on HAEC injury. Moreover, miR-637 overexpression promoted cell proliferation and angiogenesis and inhibited cell apoptosis and inflammation by targeting TRAF6 in ox-LDL-treated HAECs. Further, circ_0003575 silencing inhibited the activation of NF-κB pathway.

CONCLUSION

Circ_0003575 knockdown alleviated ox-LDL-induced HAEC damage by regulating miR-637/TRAF6 and NF-κB pathways.

Noncoding RNAs in Vascular Cell Biology and Restenosis

In-stent restenosis (ISR), characterised by ≥50% re-narrowing of the target vessel, is a common complication following stent implantation and remains a significant challenge to the long-term success of angioplasty procedures. Considering the global burden of cardiovascular diseases, improving angioplasty patient outcomes remains a key priority. Noncoding RNAs (ncRNAs) including microRNA (miRNA), long noncoding RNA (lncRNA) and circular RNA (circRNA) have been extensively implicated in vascular cell biology and ISR through multiple, both distinct and overlapping, mechanisms. Vascular smooth muscle cells, endothelial cells and macrophages constitute the main cell types involved in the multifactorial pathophysiology of ISR. The identification of critical regulators exemplified by ncRNAs in all these cell types and processes makes them an exciting therapeutic target in the field of restenosis. In this review, we will comprehensively explore the potential functions and underlying molecular mechanisms of ncRNAs in vascular cell biology in the context of restenosis, with an in-depth focus on vascular cell dysfunction during restenosis development and progression. We will also discuss the diagnostic biomarker and therapeutic target potential of ncRNAs in ISR. Finally, we will discuss the current shortcomings, challenges, and perspectives toward the clinical application of ncRNAs.

Construction of the ceRNA network in the progression of acute myocardial infarction

Acute myocardial infarction (AMI) is a common disease that induced by sudden occlusion of a coronary artery and myocardial necrosis, which causes a great medical burden worldwide. Noncoding RNAs, such as circRNA, lncRNA and miRNA, play crucial roles in the progression of cardiovascular diseases. However, the circRNA-miRNA-mRNA network in the occurrence and development of AMI needs further investigation. In this study, we downloaded three AMI datasets, including circRNA (GSE160717), miRNA (GSE24591), and mRNA (GSE66360) from GEO database. The differentially expressed candidates, and GO and KEGG functions were analyzed by RStudio, and subsequently import to PPI and Cytoscape to obtain the hub genes. By using the starbase target prediction database, we further screen the ceRNA network of circRNA-miRNA-mRNA based on the selected differentially expressed candidates. We found 46 differential expressed mRNAs, 65 miRNAs, and five circRNAs. GO functions and KEGG enrichment of the 46 mRNAs focused on immune response and functions, involving IL-17 signaling pathway, Toll-like receptor signaling pathway, cytokine-cytokine receptor interaction, TNF signaling pathway, chemokine signaling pathway, and NF-kappaB signaling pathway, which may aggravate the pathologies of AMI. PPI and Cytoscape analysis showed 10 hub genes, including TLR2, IL1B, CCL4, CCL3, CCR5, TREM1, CXCL2, NLRP3, CSF3, and CCL20. By using starbase and circinteractome databases, ceRNA network construction showed that circRNA_023461 and circRNA_400027 regulate several miRNA-mRNA axes in AMI. In summary, this study uncovered the circRNA-miRNA-mRNA network based on three AMI datasets. The differentially expressed genes, including CCL20, CCL4, CSF3, and IL1B, focus on immune functions and pathways. Furthermore, circRNA_023461 and circRNA_400027 regulate several miRNA-mRNA axes, exerting important roles in AMI progression. Our founding provides new insights into AMI and improve the therapeutic strategies for AMI.

Resveratrol protects against ox-LDL-induced endothelial dysfunction in atherosclerosis via depending on circ_0091822/miR-106b-5p-mediated upregulation of TLR4

BACKGROUND

Atherosclerosis (AS) is the most common inducer of cardiovascular diseases, and resveratrol (RSV) has played a protective function in the endothelial injury of AS. This study was to explore the molecular mechanism of RSV in oxidized low-density lipoprotein (ox-LDL)-mediated endothelial dysfunction.

METHODS

Circ_0091822, microRNA-106b-5p (miR-106b-5p) or toll-like receptor (TLR4) levels were examined using reverse transcription-quantitative polymerase chain reaction assay. Cell viability was detected via Cell Counting Kit-8 assay and angiogenesis was assessed by tube formation assay. Cell apoptosis was determined through flow cytometry. The protein analysis was conducted via western blot. Inflammatory cytokines were measured by enzyme-linked immunosorbent assay. The oxidative injury was evaluated using the commercial kits. The binding detection was performed via dual-luciferase reporter assay and RNA pull-down assay.

RESULTS

Circ_0091822 was downregulated by RSV in ox-LDL-treated endothelial cells. RSV promoted cell viability and angiogenesis while inhibiting apoptosis, inflammation, and oxidative stress after exposure to ox-LDL. The circ_0091822 knockdown relieved the ox-LDL-induced cell damages. RSV suppressed the ox-LDL-caused endothelial dysfunction via inducing the downregulation of circ_0091822. Circ_0091822 could target miR-106b-5p, and the reversal of circ_0091822 for RSV function was achieved by sponging miR-106b-5p. Circ_0091822 absorbed miR-106b-5p to elevate the level of TLR4. RSV impeded ox-LDL-induced damages by regulating miR-106b-5p/TLR4 axis.

CONCLUSION

All these findings suggested that RSV acted as an inhibitory factor in ox-LDL-induced endothelial injury via downregulating circ_0091822 to upregulate miR-106b-5p-related TLR4.

Oxygenized Low-Density Lipoprotein-Induced ASMC Dysregulation Depends on circ_0000345-Mediated Regulatory Mechanism

AIMS

Vascular smooth muscle cells are key participants in atherosclerosis. Circular RNA hsa_circ_0000345 (circ_0000345) and miR-647 are related to oxygenized low-density lipoprotein (ox-LDL)-induced arterial smooth muscle cell (ASMC) dysregulation. However, the relationship between circ_0000345 and miR-647 in ox-LDL-induced ASMC dysregulation is unclear.

METHODS

Relative levels of circ_0000345, miR-647, and PAP-associated domain containing 5 (PAPD5) mRNA in AS patient's serum and ox-LDL-induced ASMCs were detected via RT-qPCR. Gain-of-function experiments were utilized to analyze the effects of circ_0000345 upregulation on ox-LDL-induced cell proliferation, migration, invasion, and inflammatory response in ASMCs. The relationship between circ_0000345 or PAPD5 and miR-647 was validated by dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Circ_0000345 and PAPD5 were lowly expressed in AS patient's serum and ox-LDL-induced ASMCs, while miR-647 expression had an opposing trend. Mechanistically, circ_0000345 was verified as a miR-647 sponge, and miR-647 overexpression impaired the inhibitory effects of circ_0000345 upregulation on ox-LDL-induced ASMC proliferation, migration, invasion, and inflammatory response. Further experiments demonstrated that PAPD5 was a miR-647 target, and circ_0000345 adsorbed miR-647 to mediate PAPD5 expression. Also, PAPD5 inhibition relieved miR-647 silencing-mediated suppression on ox-LDL-induced ASMC proliferation, migration, invasion, and inflammatory response.

CONCLUSIONS

Circ_0000345 elevated PAPD5 expression via acting as a miR-647 sponge, resulting in alleviating ox-LDL-induced ASMC dysregulation. The study highlighted the critical role of circ_0000345 in AS.

Regulatory roles of noncoding RNAs in intervertebral disc degeneration as potential therapeutic targets (Review)

Intervertebral disc degeneration (IDD) is the leading cause of lower back pain, which is one of the primary factors that lead to disability and pose a serious economic burden. The key pathological processes involved are extracellular matrix degradation, autophagy, apoptosis, and inflammation of nucleus pulposus cells. Non-coding RNAs (ncRNAs), including microRNAs, long ncRNAs and circular RNAs, are key regulators of the aforementioned processes. ncRNAs are differentially expressed in tissues of the intervertebral disc between healthy individuals and patients and participate in the pathological progression of IDD via a complex pattern of gene regulation. However, the regulatory mechanisms of ncRNAs in IDD remain unclear. The present review summarizes the latest insights into the regulatory role of ncRNAs in IDD and sheds light on potentially novel therapeutic strategies for IDD that may be implemented in the future.

Dysfunction and ceRNA network of the tumor suppressor miR-637 in cancer development and prognosis

MicroRNAs (miRNAs) are a class of small non-coding RNAs ranging from 17 to 25 nt in length. miR-637 is down-regulated in most cancers and up-regulated only in clear cell renal cell carcinoma (ccRCC). miR-637 can target 21 protein-coding genes, which are involved in the regulation of cell growth, cell cycle, cell proliferation, epithelial-mesenchymal transition (EMT), cancer cell invasion and metastasis, etc. In glioma, the transcription factor ZEB2 can bind to the miR-637 promoter region and inhibit miR-637 expression. Besides, miR-637 could be negatively regulated by competing endogenous RNA (ceRNAs) comprising 13 circular RNA (circRNAs) and 9 long non-coding RNA (lncRNAs). miR-637 is involved in regulating five signaling pathways, including the Jak/STAT3, Wnt/β-catenin, PI3K/AKT, and ERK signaling pathways. Low miR-637 expression was significantly associated with larger tumors and later tumor node metastasis (TNM) staging in cancer patients. Low miR-637 expression was also associated with poorer overall survival (OS) in cancer patients such as glioblastoma and low-grade gliomas (GBM/LGG), non-small cell lung cancer (NSCLC), hepatocellular carcinoma (HCC), and ovarian cancer (OV). Low expression of miR-637 increases the resistance of colorectal cancer (CRC) and human cholangiocarcinoma (CHOL) cancer cells to three anticancer chemotherapeutics (gemcitabine (dFdC), cisplatin (DDP), and oxaliplatin (OXA)). Our work summarizes the abnormal expression of miR-637 in various cancers, expounds on the ceRNA regulatory network and signaling pathway involved in miR-637, and summarizes the effect of its abnormal expression on the biological behavior of tumor cells. At the same time, the relationship between the expression levels of miR-637 and its related molecules and the prognosis and pathological characteristics of patients was further summarized. Finally, our work points out the insufficiency of miR-637 in current studies and is expected to provide potential clues for future miR-637-related studies.

Circ_0091822 aggravates ox-LDL-induced endothelial cell injury through targeting the miR-661/RAB22A axis

BACKGROUND

Endothelial dysfunction is considered to be an important factor in the pathogenesis of atherosclerosis. Circular RNAs (circRNAs) have been confirmed to participate in the development of atherosclerosis. Nevertheless, the role and mechanism of circ_0091822 in atherosclerosis have not been studied yet.

METHODS

The expression of circ_0091822, miR-661 and RAB22A were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were estimated by enzyme-linked immunosorbent assay (ELISA). Cell viability was analyzed by Cell Counting Kit-8 (CCK-8) assay, cell proliferation was evaluated by EdU assay, and cell apoptosis was gauged by flow cytometry. Western blot was performed to assess the protein levels of Bax, Cleaved-caspase-3 and RAB22A. The interaction among miR-661 and circ_0091822 or RAB22A was verified by dual-luciferase reporter assayRESULTS:Ox-LDL enhanced the expression of circ_0091822 in HUVECs. It also constrained proliferation, promotes apoptosis and inflammation in HUVECs, and down-regulation of circ_0091822 attenuated these effects. Mechanically, circ_0091822 could serve as a sponge of miR-661, miR-661 interference rescued circ_0091822 inhibition-mediated effect on the biological functions in ox-LDL-induced HUVECs. Additionally, RAB22A was a target of miR-661, and its overexpression could partially overturn the negative regulation of miR-661 on ox-LDL-treated HUVECs injury. Importantly, circ_0091822 sponged miR-661 to positively regulate RAB22A expression.

CONCLUSION

Circ_0091822 contributed to cell injury by targeting miR-661/RAB22A axis in ox-LDL-stimulated HUVECs.

Mechanisms of Oxidized LDL-Mediated Endothelial Dysfunction and Its Consequences for the Development of Atherosclerosis

Atherosclerosis is an immuno-metabolic disease involving chronic inflammation, oxidative stress, epigenetics, and metabolic dysfunction. There is compelling evidence suggesting numerous modifications including the change of the size, density, and biochemical properties in the low-density lipoprotein (LDL) within the vascular wall. These modifications of LDL, in addition to LDL transcytosis and retention, contribute to the initiation, development and clinical consequences of atherosclerosis. Among different atherogenic modifications of LDL, oxidation represents a primary modification. A series of pathophysiological changes caused by oxidized LDL (oxLDL) enhance the formation of foam cells and atherosclerotic plaques. OxLDL also promotes the development of fatty streaks and atherogenesis through induction of endothelial dysfunction, formation of foam cells, monocyte chemotaxis, proliferation and migration of SMCs, and platelet activation, which culminate in plaque instability and ultimately rupture. This article provides a concise review of the formation of oxLDL, enzymes mediating LDL oxidation, and the receptors and pro-atherogenic signaling pathways of oxLDL in vascular cells. The review also explores how oxLDL functions in different stages of endothelial dysfunction and atherosclerosis. Future targeted pathways and therapies aiming at reducing LDL oxidation and/or lowering oxLDL levels and oxLDL-mediated pro-inflammatory responses are also discussed.

Circular RNA circ_0061140 accelerates hypoxia-induced glycolysis, migration, and invasion in lung adenocarcinoma through the microRNA-653/hexokinase 2 (HK2) axis

Circular RNA (circRNA) is considered to be an essential regulator of multiple human malignancies. However, the role and molecular mechanism of circ_0061140 in lung adenocarcinoma ((LUAD) remain elusive. The levels of circ_0061140, microRNA (miR)-653 and hexokinase 2 (HK2) were examined by RT-qPCR. Downstream targets of circ_0061140 were predicted by circinteractome website and verified by luciferase reporter and RIP assays. HK2 protein level was assessed via Western blotting. The migratory and invasive abilities of LUAD cells were assessed via wound healing and transwell assays. It was uncovered that circ_0061140 level was elevated in LUAD samples, and the high level of circ_0061140 was related to poor survival rate of LUAD patients. Circ_0061140 deletion inhibited glycolysis, migration and invasion of hypoxia-treated LUAD cells. Moreover, circ_0061140 could modulate HK2 level by absorbing miR-653. Furthermore, miR-653 silence or HK2 addition neutralized the effects of circ_0061140 knockdown on LUAD progression under hypoxia. This study elaborated that circ_0061140 accelerated hypoxia-triggered glycolysis, migration and invasion in LUAD cells via downregulating miR-653 and increasing HK2 expression.

Hsa_circ_0134111 promotes intervertebral disc degeneration via sponging miR-578

Intervertebral disc degeneration (IDD) is a chronic degenerative and age-dependent process characterized by aberrant apoptosis, proliferation, synthesis, and catabolism of the extracellular matrix of the nucleus pulposus (NP) cells. Recently, studies showed that circular RNAs play important roles in the development of many diseases. However, the role of circRNAs in IDD development remains unknown. We showed that circ_0134111 level was overexpressed in IDD tissue samples as compar-ed to control tissues. The upregulation of circ_0134111 was more drastic in the moderate and severe IDD cases than in those with mild IDD. In addition, we showed that interleukin-1β and tumor necrosis factor-α exposure significantly enhanced circ_0134111 expression in NP cells. Furthermore, ectopic expression of circ_0134111 induced proliferation, pro-inflammatory cytokine secretion, and ECM degradation in the NP cells. We also showed that circ_0134111 directly interacted with microRNA (miR)-578 in NP cells where elevated expression of circ_0134111 enhanced the ADAMTS-5 and MMP-9 expression. Moreover, miR-578 expression was significantly decreased in IDD patients and the miR-578 expression was negatively correlated with circ_0134111 expression in the IDD samples. Interleukin-1β and tumor necrosis factor-α exposure significantly decreased miR-578 levels in NP cells, in which ectopic miR-578 expression inhibited cell growth, pro-inflammatory cytokine expression, and ECM degradation. Finally, we showed that circ_0134111 overexpression induced the IDD-related phenotypic changes through inhibiting miR-578. These data suggested that circ_0134111 could promote the progression of IDD through enhancing aberrant NP cell growth, inflammation, and ECM degradation partly via regulating miR-578.

Circular RNA_0033596 aggravates endothelial cell injury induced by oxidized low-density lipoprotein via microRNA-217-5p /chloride intracellular channel 4 axis

In recent years, the modulatory functions of some circular RNAs (circRNAs) in the pathogenesis of atherosclerosis (AS) have been reported. Nonetheless, the role of circular RNA_0033596 (circ_0033596) in AS and its mechanism remains unclarified. In this study, oxidized low-density lipoprotein (ox-LDL) was applied to treat human umbilical vein endothelial cells (HUVECs) to establish a cell model of endothelial cell injury. Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to detect the expression of circ_0033596, microRNA-217-5p (miR-217-5p), and chloride intracellular channel 4 (CLIC4) in HUVECs. The binding sites between circ_0033596 and miR-217-5p, as well as between miR-217-5p and CLIC4 mRNA 3ʹUTR were determined through a dual-luciferase reporter gene assay. It was found that circ_0033596 expression was increased in ox-LDL-induced HUVECs. After ox-LDL stimulation, HUVEC viability and cell cycle progression were inhibited, and the apoptosis was promoted, while circ_0033596 overexpression aggravated these effects. MiR-217-5p was identified as a downstream target of circ_0033596, and circ_0033596 negatively regulated miR-217-5p expression. CLIC4 was identified as miR-217-5p’s downstream target gene and could be positively modulated by circ_0033596. All in all circ_0033596 aggravates ox-LDL-induced HUVEC apoptosis by regulating the miR-217-5p/CLIC4 axis, by which circ_0033596 participates in the pathogenesis of AS.

Epigenetic Regulation in Pathology of Atherosclerosis: A Novel Perspective

Atherosclerosis, characterized by atherosclerotic plaques, is a complex pathological process that involves different cell types and can be seen as a chronic inflammatory disease. In the advanced stage, the ruptured atherosclerotic plaque can induce deadly accidents including ischemic stroke and myocardial infarction. Epigenetics regulation, including DNA methylation, histone modification, and non-coding RNA modification. maintains cellular identity via affecting the cellular transcriptome. The epigenetic modification process, mediating by epigenetic enzymes, is dynamic under various stimuli, which can be reversely altered. Recently, numerous studies have evidenced the close relationship between atherosclerosis and epigenetic regulations in atherosclerosis, providing us with a novel perspective in researching mechanisms and finding novel therapeutic targets of this serious disease. Here, we critically review the recent discoveries between epigenetic regulation mechanisms in atherosclerosis.