Exploring the regulatory roles of circular RNAs in the pathogenesis of atherosclerosis

Hsa_circ_0032389 Enhances Proliferation and Migration in PDGF-BB-Induced Human Aortic Vascular Smooth Muscle Cells

Circular RNA (circRNAs) has been confirmed to participate in atherosclerosis (AS) progression. However, the role and mechanism of hsa_circ_0032389 in AS process still need to be further revealed. This study evaluates the role and mechanism of hsa_circ_0032389 in AS process. Platelet-derived growth factor-BB (PDGF-BB) was used to induce human aortic vascular smooth muscle cells (HA-VSMCs). The expression levels of hsa_circ_0032389, microRNA (miR)-513a-5p, and fibroblast growth factor receptor substrate 2 (FRS2) were examined by quantitative real-time PCR. Cell proliferation and migration were analyzed using cell counting kit 8 assay, flow cytometry, EdU assay, transwell assay, and wound healing assay. Protein expression was assessed using western blot analysis. Dual-luciferase reporter and RIP assays were used to confirm RNA interaction. Hsa_circ_0032389 was overexpressed in PDGF-BB-induced HA-VSMCs, and its downregulation inhibited HA-VSMC viability, cell cycle, EdU positive cell rate, migratory cell number, and wound closure rate under PDGF-BB treatment. The luciferase activity of hsa_circ_0032389wt could be reduced by miR-513a-5p mimic, and both hsa_circ_0032389 and miR-513a-5p were enriched in anti-Ago2, confirming that miR-513a-5p could be sponged by hsa_circ_0032389. MiR-513a-5p inhibitor reversed the effect of hsa_circ_0032389 knockdown on PDGF-BB-induced HA-VSMC viability, cell cycle, EdU positive cell rate, migratory cell number, and wound closure rate. Moreover, the luciferase activity of FRS2wt was reduced by miR-513a-5p mimic, and both FRS2 and miR-513a-5p were enriched in anti-Ago2, verifying that FRS2 was targeted by miR-513a-5p. MiR-513a-5p suppressed PDGF-BB-induced HA-VSMC viability, cell cycle, EdU positive cell rate, migratory cell number, and wound closure rate by targeting FRS2. Our results indicated that hsa_circ_0032389 enhanced PDGF-BB-induced HA-VSMC proliferation and migration via regulating miR-513a-5p/FRS2 axis.

Tanshinone IIA attenuates ox-LDL-induced endothelial cell injury by inhibiting NF-kapaB pathway via circ_0000231/miR-590-5p/TXNIP axis

Tanshinone IIA (TSIIA) exhibits inhibitory function in atherosclerosis (AS) progression, and circular RNAs (circRNAs) are pivotal regulators in AS. However, the relation between TSIIA and circ_0000231 in AS pathogenesis remains unknown. In this study, oxidized low-density lipoprotein (ox-LDL) was used to establish AS cell model. Treatment of ox-LDL inhibited cell growth but promoted apoptosis, inflammation, and oxidative stress. Then, TSIIA was shown to attenuate ox-LDL-induced endothelial injury. Furthermore, the protective effect of TSIIA against ox-LDL-induced endothelial cell injury was reversed by circ_0000231. Circ_0000231 was identified as a miR-590-5p sponge. Also, miR-590-5p downregulation restored the protection of TSIIA for endothelial cell function. Moreover, circ_0000231 was found to upregulate thioredoxin interacting protein (TXNIP) level via targeting miR-590-5p. TXNIP overexpression mitigated the regulatory function of circ_0000231 knockdown after co-treatment with ox-LDL and TSIIA. TXNIP upregulation recovered the inhibitory regulation of TSIIA in ox-LDL-induced cell damage. In addition, TSIIA inactivated NF-kapaB (NF-κB) signaling pathway via regulating miR-590-5p/TXNIP axis by downregulating circ_0000231. All these results suggested that TSIIA inhibited ox-LDL-induced AS progression in endothelial cells by affecting NF-κB pathway via circ_0000231/miR-590-5p/TXNIP.

Circular RNA circ_0008896 contributes to oxidized low-density lipoprotein-induced aortic endothelial cell injury via targeting miR-188-3p/NOD2 axis

We aimed to investigate the role and mechanism of circ_0008896 in Atherosclerosis (AS) by using oxidized low-density lipoprotein (ox-LDL)-induced human aortic endothelial cell (HAECs). Levels of genes and proteins were measured by quantitative real-time PCR and Western blot. Functional experiments, including enzyme-linked immunosorbent assay analysis, cell counting kit-8, 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, tube formation assays and the detection of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) generation, were performed to investigate the role of circ_0008896 on ox-LDL-induced HAEC damage. Circ_0008896 was increased in AS patients and ox-LDL-stimulated HAECs. Functionally, circ_0008896 knockdown reversed ox-LDL-induced inflammatory response, oxidative stress, apoptosis as well as arrest of proliferation and angiogenesis in HAECs in vitro. Mechanistically, circ_0008896 functioned as a sponge for miR-188-3p to relieve the repression of miR-188-3p on its target NOD2. A series of rescue experiments showed that miR-188-3p inhibition attenuated the protective effects of circ_0008896 knockdown on ox-LDL-stimulated HAECs, and NOD2 overexpression abolished the beneficial action of miR-188-3p in the suppression of inflammatory response and oxidative stress, and the promotion of cell growth and angiogenesis in HAECs under ox-LDL treatment. Circ_0008896 silencing attenuates ox-LDL-induced inflammatory response, oxidative stress, and growth arrest in HAECs in vitro, adding further understanding for the pathogenesis of AS.

Role of Terpenophenolics in Modulating Inflammation and Apoptosis in Cardiovascular Diseases: A Review

One in every three deaths worldwide is caused by cardiovascular diseases (CVDs), estimating a total of 17.9 million deaths annually. By 2030, it is expected that more than 24 million people will die from CVDs related complications. The most common CVDs are coronary heart disease, myocardial infarction, stroke, and hypertension. A plethora of studies has shown inflammation causing both short-term and long-term damage to the tissues in many organ systems, including the cardiovascular system. In parallel to inflammation processes, it has been discovered that apoptosis, a mode of programmed cell death, may also contribute to CVD development due to the loss of cardiomyocytes. Terpenophenolic compounds are comprised of terpenes and natural phenols as secondary metabolites by plants and are commonly found in the genus Humulus and Cannabis. A growing body of evidence has shown that terpenophenolic compounds exhibit protective properties against inflammation and apoptosis within the cardiovascular system. This review highlights the current evidence elucidating the molecular actions of terpenophenolic compounds in protecting the cardiovascular system, i.e., bakuchiol, ferruginol, carnosic acid, carnosol, carvacrol, thymol and hinokitiol. The potential of these compounds is discussed as the new nutraceutical drugs that may help to decrease the burden of cardiovascular disorders.

CIRC_0114428 INFLUENCES THE PROGRESSION OF SEPTIC ACUTE KIDNEY INJURY VIA REGULATING MIR-370-3P/TIMP2 AXIS

ABSTRACT

Background: Septic acute kidney injury (AKI) is a serious complication of sepsis, which greatly threatened the life safety of critically ill patients. Recently, circular RNA is considered to be implicated in sepsis-induced renal cell damage. However, the role of circ_0114428 in sepsis AKI is still unclear. Methods: LPS was used to establish a sepsis-related AKI cell model. The expression of circ_0114428, microRNA (miR)-370-3p, tissue inhibitor of metalloproteinase-2 (TIMP2), Proliferating cell nuclear antigen, Bax, and Bcl-2 were detected by quantitative real-time polymerase chain reaction and Western blot. Cell counting kit 8 and enzyme-linked immunosorbent assay were used to measure cell proliferation ability and the secretion of inflammatory factors (tumor necrosis factor α, interleukin 1β, and interleukin 6), respectively. Cell cycle and apoptosis rate were analyzed by flow cytometry. Caspase-3 assay kits were used to detect Caspase-3 activity. Interaction between miR-370-3p and circ_0114428 or TIMP2 was analyzed by bioinformatics analysis, a dual-luciferase reporter assay, and RNA immunoprecipitation assay. Results: Circ_0114428 was upregulated in septic AKI serum samples and LPS-induced HK2 cells. The knockdown of circ_0114428 notably promoted cell proliferation and cycle, whereas it restrained cell inflammation and apoptosis in LPS-stimulated HK2 cells. Subsequent mechanism analysis revealed that miR-370-3p was a target of circ_0114428, and miR-370-3p inhibition could rescue the effects of circ_0114428 downregulation on LPS-induced cell injury. Meanwhile, TIMP2 was a target gene of miR-370-3p. miR-370-3p mimic could attenuate LPS-induced cell injury, whereas these impacts were overturned by overexpressed TIMP2. Furthermore, circ_0114428 enhanced TIMP2 protein expression by sponging miR-370-3p. Conclusion: Our data demonstrated that circ_0114428 contributed to septic AKI progression by regulating miR-370-3p-mediated TIMP2 expression, which provided a promising target for septic AKI treatment.

Identification of a Novel Angiogenesis Signalling circSCRG1/miR-1268b/NR4A1 Pathway in Atherosclerosis and the Regulatory Effects of TMP-PF In Vitro

Angiogenesis contributes to plaque instability in atherosclerosis and further increases cardio-cerebrovascular risk. Circular RNAs (circRNAs) are promising biomarkers and potential therapeutic targets for atherosclerosis. Previous studies have demonstrated that tetramethylpyrazine (TMP) and paeoniflorin (PF) combination treatment (TMP-PF) inhibited oxidized low-density lipoprotein (ox-LDL)-induced angiogenesis in vitro. However, whether circRNAs regulate angiogenesis in atherosclerosis and whether TMP-PF can regulate angiogenesis-related target circRNAs in atherosclerosis are unknown. In this study, human RNA sequencing (RNA-seq) data were analysed to identify differentially expressed (DE) circRNAs in atherosclerosis and to obtain angiogenesis-associated circRNA-microRNA (miRNA)-messenger RNA (mRNA) networks. Target circRNA-related mechanisms in angiogenesis in atherosclerosis and the regulatory effects of TMP-PF on target circRNA signalling were studied in ox-LDL-induced human umbilical vein endothelial cells (HUVECs) by cell proliferation, migration, tube formation, and luciferase reporter assays, real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. A novel circRNA (circular stimulator of chondrogenesis 1, circSCRG1) was initially identified associated with angiogenesis in atherosclerosis, and circSCRG1 silencing up-regulated miR-1268b expression, increased nuclear receptor subfamily 4 group A member 1 (NR4A1) expression and then promoted ox-LDL-induced angiogenesis. TMP-PF (1 μmol/L TMP combined with 10 μmol/L PF) up-regulated circSCRG1 expression, mediated miR-1268b to suppress NR4A1 expression and then inhibited ox-LDL-induced angiogenesis. However, circSCRG1 silencing abolished the inhibitory effects of TMP-PF on ox-LDL-induced angiogenesis, which were rescued by the miR-1268b inhibitor. In conclusion, circSCRG1 might serve as a new target regulating angiogenesis in atherosclerosis via the circSCRG1/miR-1268b/NR4A1 axis and TMP-PF could regulate the circSCRG1/miR-1268b/NR4A1 axis to inhibit angiogenesis in atherosclerosis in vitro, indicating a novel angiogenesis signalling circSCRG1/miR-1268b/NR4A1 pathway in atherosclerosis and the regulatory effects of TMP-PF, which might provide a new pharmaceutical strategy to combat atherosclerotic plaque instability.

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.

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.

Non-Coding RNAs in Regulating Plaque Progression and Remodeling of Extracellular Matrix in Atherosclerosis

Non-coding RNAs (ncRNAs) regulate cell proliferation, migration, differentiation, inflammation, metabolism of clinically important biomolecules, and other cellular processes. They do not encode proteins but are involved in the regulatory network of various proteins that are directly related to the pathogenesis of diseases. Little is known about the ncRNA-associated mechanisms of atherosclerosis and related cardiovascular disorders. Remodeling of the extracellular matrix (ECM) is critical in the pathogenesis of atherosclerosis and related disorders; however, its regulatory proteins are the potential subjects to explore with special emphasis on epigenetic regulatory components. The activity of regulatory proteins involved in ECM remodeling is regulated by various ncRNA molecules, as evident from recent research. Thus, it is important to critically evaluate the existing literature to enhance the understanding of nc-RNAs-regulated molecular mechanisms regulating ECM components, remodeling, and progression of atherosclerosis. This is crucial since deregulated ECM remodeling contributes to atherosclerosis. Thus, an in-depth understanding of ncRNA-associated ECM remodeling may identify novel targets for the treatment of atherosclerosis and other cardiovascular diseases.

IL-1β promotes A7r5 and HASMC migration and invasion via the p38-MAPK/Angpt-2 pathway

The migration, proliferation, and inflammatory factor secretion of vascular smooth muscle cells (VSMCs) are involved in the important pathological processes of several vascular occlusive diseases, including coronary atherosclerosis (CAS). Interleukin 1β(IL-1β), as a bioactive mediator of VSMC synthesis and secretion, can promote the pathological progress of CAS. In this study, we further explored the underlying molecular mechanisms by which IL-1β regulates VSMC migration, invasion. We pretreated A7r5 and HASMC with IL-1β for 24 h, and measured the expression of IL-1β, proliferating cell nuclear antigen (PCNA), cyclin D1, matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 2 (MMP9) in the cells by Western blotting. Cell migration and invasion ability were measured by Transwell and wound healing assays. Cell viability was measured by an MTT assay. We found that IL-1β upregulated the expression of proliferation-related proteins (PCNA and Cyclin D1) in A7r5 and HASMC, and induces the secretion of MMP2 and MMP9, promotes cell invasion and migration. In addition, in A7r5 and HASMCs treated with IL-1β, the expression of Angiopoietin-2 (Angpt-2) increased in a time-dependent manner, transfection with si-Angpt-2 suppressed cell migration and invasion, with downregulated MMP2 and MMP9 expression. Parallelly, we further found that the p38-MAPK pathway is activated in cells induced by IL-1β, p38-MAPK inhibitors can down-regulate the expression of Angpt-2. Collectively, these data demonstrated that IL-1β promotes A7r5 and HASMC migration and invasion via the p38-MAPK/Angpt-2 pathway.

Circular RNAs in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory lesion of the arterial vessel wall caused by a variety of complex factors. Furthermore, it is a major cause of cardiovascular disease and a leading cause of death. Circular RNAs (circRNAs) are a new family of endogenous non-coding RNAs with unique covalently closed loops that have sparked interest due to their unique characteristics and potential diagnostic and therapeutic applications in various diseases. A growing number of studies have shown that circRNAs can be used as biomarkers for the diagnosis and treatment of AS. In this article, we review the biogenesis, classification as well as functions of circRNA and summarize the research on circRNA as a diagnostic biomarker for AS. Finally, we describe the regulatory capacity of circRNA in AS pathogenesis through its pathogenesis and demonstrate the potential therapeutic role of circRNA for AS.

Circular RNA: A promising new star for the diagnosis and treatment of colorectal cancer

Background

Colorectal cancer (CRC) is one of the most common malignant tumors of the digestive tract. According to the research of circular RNAs in the CRC field, compared with linear RNAs, circular RNAs are a special type of noncoding RNA that are covalently closed circular structures, which have no 5' cap structure and 3' polyA tail and are not affected by RNA exonuclease and actinomycin D.

Biological functions

Notably, circular RNAs have a high degree of stability and potential effect on gene regulation. Meanwhile, circular RNAs are involved in the sponge action of microRNAs and mediate protein translation and direct binding, alternative splicing, and histone modification.

Relationships with CRC

Studies have shown that circular RNAs are related to the proliferation, invasion, recurrence, metastasis, ferroptosis, apoptosis, and chemotherapy resistance of CRC.

Conclusions

This article provides a brief review based on the source, structural characteristics, mechanisms, biological functions of circular RNAs, and the relationships between CRC.