CircRSF1 contributes to endothelial cell growth, migration and tube formation under ox-LDL stress through regulating miR-758/CCND2 axis

Construction of competing endogenous RNA networks in systemic lupus erythematosus by integrated analysis

Objective

Systemic lupus erythematosus (SLE) is a disease characterised by immune inflammation and damage to multiple organs. Recent investigations have linked competing endogenous RNAs (ceRNAs) to lupus. However, the exact mechanism through which the ceRNAs network affects SLE is still unclear. This study aims to investigate the regulatory functions of the ceRNAs network, which are important pathways that control the pathophysiological processes of SLE.

Methods

CircRNA microarray for our tested assays were derived from bone marrow samples from three healthy individuals and three SLE patients in our hospital. The other sequencing data of circRNA, miRNA and mRNA were obtained from Gene Expression Omnibus (GEO) datasets. Using the limma package of R program, the differential expression of mRNA and miRNA in the GEO database was discovered. Then predicted miRNA-mRNA and circRNA-miRNA were established using miRMap, miRanda, miRDB, TargetScan, and miTarBase. CircRNA-miRNA-mRNA ceRNA network was constructed using Cytoscape, and hub genes were screened using a protein-protein interaction network. Immune infiltration analysis of the hub gene was also performed by CIBERSORT and GSEA.

Results

230 overlapped circRNAs, 86 DEmiRNAs and 2083 DEmRNAs were identified in SLE patients as compared to healthy controls. We constructed a circRNA-miRNA-mRNA ceRNAs network contained 11 overlapped circRNAs, 9 miRNAs and 51 mRNAs. ESR1 and SIRT1 were the most frequently associated protein-protein interactions in the PPI network. KEGG analysis showed that DEGs was enriched in FoxO signaling pathway as well as lipids and atherosclerosis. We constructed a novel circRNA-miRNA-mRNA ceRNA network (HSA circ 0000345- HSA miR-22-3-P-ESR1/SIRT1) that may have a major impact on SLE.

Conclusion

Through this bioinformatics and integrated analysis, we suggest a regulatory role for ceRNA network in the pathogenesis and treatment of SLE.

Noncoding RNAs in atherosclerosis: regulation and therapeutic potential

Atherosclerosis, a chronic disease of arteries, results in high mortality worldwide as the leading cause of cardiovascular disease. The development of clinically relevant atherosclerosis involves the dysfunction of endothelial cells and vascular smooth muscle cells. A large amount of evidence indicates that noncoding RNAs, such as microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), are involved in various physiological and pathological processes. Recently, noncoding RNAs were identified as key regulators in the development of atherosclerosis, including the dysfunction of endothelial cells, and vascular smooth muscle cells and it is pertinent to understand the potential function of noncoding RNAs in atherosclerosis development. In this review, the latest available research relates to the regulatory role of noncoding RNAs in the progression of atherosclerosis and the therapeutic potential for atherosclerosis is summarized. This review aims to provide a comprehensive overview of the regulatory and interventional roles of ncRNAs in atherosclerosis and to inspire new insights for the prevention and treatment of this disease.

KLF15 Transcriptionally Activates ATG14 to Promote Autophagy and Attenuate Damage of ox-LDL-Induced HAECs

Kruppel-like factor 15 (KLF15) is involved in many cardiovascular diseases and is abnormally expressed in atherosclerosis (AS), but the regulatory mechanism of KLF15 in AS has not been reported so far. RT-qPCR was used to detect the expression of KLF15 and ATG14 in AS patients. Subsequently, human aortic endothelial cells (HAECs) were induced by oxidized low densitylipoprotein (ox-LDL), and the expression of KLF15 in model cells was detected. KLF15 was overexpressed in cells by lipofection transfection, and then CCK8, flow cytometry, Western blot, ELISA, and related assay kits were used to detect cell viability, apoptosis, inflammatory response as well as oxidative stress, respectively. The targeted regulatory relationship between KLF15 and autophagy-related 14 (ATG14) was detected by ChIP and luciferase reporter assays. Following ATG14 silencing in KLF15-overexpressing cells, immunofluorescence and Western blot were used to detect the autophagy. Finally, after the addition of 3-Methyladenine (3-MA), an autophagy inhibitor, the aforementioned experiments were conducted again to further explore the mechanism. The expression of KLF15 and ATG14 were decreased in AS patients and ox-LDL-induced HAECs. Overexpression of KLF15 protected ox-LDL-induced HAECs from damage, which might be achieved through transcriptional regulation of ATG14. In addition, KLF15 could promote autophagy through transcriptional activation of ATG14. KLF15 transcriptionally activated ATG14 to promote autophagy and attenuate damage of ox-LDL-induced HAECs.

CircCHMP5 Contributes to Ox-LDL-induced Endothelial Cell Injury Through the Regulation of MiR-532-5p/ROCK2 axis

BACKGROUND

Aberrant expression of circular RNA (circRNA) has been demonstrated to be related to atherosclerosis (AS) formation. However, the mechanism of circCHMP5 (also known as hsa_circ_0003575) in AS formation remains unclear.

METHODS

Oxidized low-density lipoprotein (ox-LDL) was used to treat human umbilical vein endothelial cells (HUVECs) to construct a cell injury model. The expression level of circCHMP5, miR-532-5p, and Rho-associated protein kinase 2 (ROCK2) was measured using quantitative real-time PCR. Cell cycle, apoptosis, proliferation, and angiogenesis were determined by flow cytometry, 5-ethynyl-2'-deoxyuridine (EdU) assay, and tube formation assay. In addition, the protein expression of apoptosis markers, inflammation factors, and ROCK2 was detected by western blot analysis. The interaction between miR-532-5p and circCHMP5 or ROCK2 was assessed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

RESULTS

Our results indicated that circCHMP5 was overexpressed in ox-LDL-induced HUVECs. CircCHMP5 knockdown promoted cell cycle, proliferation, and angiogenesis while inhibiting apoptosis and inflammation in ox-LDL-induced HUVECs. MiR-532-5p could be sponged by circCHMP5, and its inhibitor reversed the negative regulation of si-circCHMP5 on ox-LDL-induced HUVECs injury. ROCK2, a target of miR-532-5p, reversed the inhibition effect of miR-532-5p on ox-LDL-induced HUVECs injury. Furthermore, we confirmed that circCHMP5 upregulated ROCK2 by sponging miR-532-5p.

CONCLUSION

To sum up, our data showed that circCHMP5 regulated the miR-532-5p/ROCK2 axis to accelerate ox-LDL-induced HUVECs injury, confirming that circCHMP5 might be a potential target for AS treatment.

Hsa_ circ_0006867 regulates ox-LDL-induced endothelial injury via the miR-499a-3p/ADAM10 axis

Circular RNAs (circRNAs) have been reported to participate in the development of various diseases. In this study, we investigated the potential mechanism underlying the role of circRNAs in atherosclerosis. Human umbilical vein endothelial cells (HUVECs) were treated with 100μg/mL oxidized low-density lipoprotein (ox-LDL) to simulate atherosclerosis. We observed that hsa_circ_0006867 (circ_0006867), a circRNA markedly increased in ox-LDL-treated endothelial cells, acted as a molecular sponge of miR-499a-3p and regulated its expression. This interaction led to changes in the downstream target gene ADAM10, thus affecting cell apoptosis and migration. Thus, our study suggests that circ_0006867 regulates ox-LDL-induced endothelial injury via the circ_0006867/miR-499a-3p/ADAM10 axis, indicating its potential as an exploitable therapeutic target for atherosclerosis.

The potential role and mechanism of circRNAs in foam cell formation

Atherosclerosis is a significant risk factor for coronary heart disease (CHD) and myocardial infarction (MI). Atherosclerosis develops during foam cell generation, which is caused by an imbalance in cholesterol uptake, esterification, and efflux. LOX-1, SR-A1, and CD36 all increased cholesterol uptake. ACAT1 and ACAT2 promote free cholesterol (FC) esterification to cholesteryl esters (CE). The hydrolysis of CE to FC was aided by nCEH. FC efflux was promoted by ABCA1, ABCG1, ADAM10, and apoA-I. SR-BI promotes not only cholesterol uptake but also FC efflux. Circular RNAs (circRNAs), which are single-stranded RNAs with a closed covalent circular structure, have emerged as promising biomarkers and therapeutic targets for atherosclerosis due to their highly tissue, cell, and disease state-specific expression profiles. Numerous studies have shown that circRNAs regulate foam cell formation, acting as miRNA sponges to influence atherosclerosis development by regulating the expression of SR-A1, CD36, ACAT2, ABCA1, ABCG1, ADAM10, apoA-I, SR-B1. Several circRNAs, including circ-Wdr91, circ 0004104, circRNA0044073, circRNA_0001805, circDENND1B, circRSF1, circ 0001445, and circRNA 102682, are potential biomarkers for atherosclerosis to better evaluate cardiovascular risk. It is difficult to deliver synthetic therapeutic circRNAs to the desired target tissues. Nanotechnology, such as GA-RM/GZ/PL, may be an important solution to this problem. In this review, we focus on the potential role and mechanism of circRNA/miRNA axis in foam cell formation in the hopes of discovering new targets for the diagnosis, prevention, and treatment of atherosclerosis.

Circular RNAs Variously Participate in Coronary Atherogenesis

Over the past decade, numerous studies have shown that circular RNAs (circRNAs) play a significant role in coronary artery atherogenesis and other cardiovascular diseases. They belong to the class of non-coding RNAs and arise as a result of non-canonical splicing of premature RNA, which results in the formation of closed single-stranded circRNA molecules that lack 5'-end caps and 3'-end poly(A) tails. circRNAs have broad post-transcriptional regulatory activity. Acting as a sponge for miRNAs, circRNAs compete with mRNAs for binding to miRNAs, acting as competing endogenous RNAs. Numerous circRNAs are involved in the circRNA-miRNA-mRNA regulatory axes associated with the pathogenesis of cardiomyopathy, chronic heart failure, hypertension, atherosclerosis, and coronary artery disease. Recent studies have shown that сirc_0001445, circ_0000345, circ_0093887, сircSmoc1-2, and circ_0003423 are involved in the pathogenesis of coronary artery disease (CAD) with an atheroprotective effect, while circ_0002984, circ_0029589, circ_0124644, circ_0091822, and circ_0050486 possess a proatherogenic effect. With their high resistance to endonucleases, circRNAs are promising diagnostic biomarkers and therapeutic targets. This review aims to provide updated information on the involvement of atherogenesis-related circRNAs in the pathogenesis of CAD. We also discuss the main modern approaches to detecting and studying circRNA-miRNA-mRNA interactions, as well as the prospects for using circRNAs as biomarkers and therapeutic targets for the treatment of cardiovascular diseases.

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.

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.

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.

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.

CircRNA-miRNA interactions in atherogenesis

Atherosclerosis is the major cause of coronary artery disease (CAD) which includes unstable angina, myocardial infarction, and heart failure. The onset of atherogenesis, a process of atherosclerotic lesion formation in the intima of arteries, is driven by lipid accumulation, a vicious cycle of reactive oxygen species (ROS)-induced oxidative stress and inflammatory reactions leading to endothelial cell (EC) dysfunction, vascular smooth muscle cell (VSMC) activation, and foam cell formation which further fuel plaque formation and destabilization. In recent years, there is a surge in the number of publications reporting the involvement of circular RNAs (circRNAs) in the pathogenesis of cardiovascular diseases, cancers, and metabolic syndromes. These studies have advanced our understanding on the biological functions of circRNAs. One of the most common mechanism of action of circRNAs reported is the sponging of microRNAs (miRNAs) by binding to the miRNAs response element (MRE), thereby indirectly increases the transcription of their target messenger RNAs (mRNAs). Individual networks of circRNA-miRNA-mRNA associated with atherogenesis have been extensively reported, however, there is a need to connect these findings for a complete overview. This review aims to provide an update on atherogenesis-related circRNAs and analyze the circRNA-miRNA-mRNA interactions in atherogenesis. The atherogenic mechanisms and clinical relevance of each atherogenesis-related circRNA were systematically discussed for better understanding of the knowledge gap in this area.

Hsa_circ_0000345 inhibits cell proliferation, migration and invasion of nasopharyngeal carcinoma cells via miR-513a-3p/PTEN axis

BACKGROUND

Hsa_circ_0000345 has been reported to be down-regulated in nasopharyngeal carcinoma (NPC). Whether hsa_circ_0000345 can exert antitumor effect in NPC remains unclear. This study aimed to investigate the possible biological role of hsa_cic_0000345 in suppressing the progression of NPC.

METHODS

Hsa_circ_0000345 expression was detected in normal nasopharynx epithelial cells (NP69) and NPC cell lines (SUNE1, HONE1, 6-10B and HNE1). The influence of hsa_circ_0000345 on cell proliferation, migration and invasion of NPC cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and transwell assays. Quantitative real-time PCR and western blot were performed to examine gene and protein expression, respectively. Luciferase reporter assay was carried out to verify the relationship among hsa_circ_0000345, miR-513a-3p and phosphatase and tensin homolog deleted on chromosome 10 (PTEN).

RESULTS

Compared with NP69 cells, hsa_circ_0000345 was down-regulated in NPC cells. Moreover, hsa_circ_0000345 overexpression repressed cell proliferation, migration and invasion of SUNE1 cells, whereas hsa_circ_0000345 knockdown promoted cell proliferation, migration and invasion of 6-10B cells. Furthermore, hsa_circ_0000345 promoted PTEN expression by sponging miR-513a-3p. Both miR-513a-3p overexpression and PTEN knockdown promoted cell proliferation, migration and invasion of SUNE1 cells, which were effectively abolished by hsa_circ_0000345 up-regulation.

CONCLUSION

Hsa_circ_0000345 inhibits cell proliferation, migration and invasion of NPC cells via miR-513a-3p/PTEN axis, thereby suppressing the progression of NPC. Thus, this work suggests that hsa_circ_0000345 may be a potential biomarker for diagnosis and treatment of NPC.

Circ_0124644 enhances ox-LDL-induced cell damages in human umbilical vein endothelial cells through upregulating FOXO4 by sponging miR-370-3p

BACKGROUND: Circular RNA circ_0124644 has crucial regulation in the progression of coronary artery diseases, including atherosclerosis (AS). The aim of this study was to explore the regulatory mechanism of circ_0124644 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial injury in human umbilical vein endothelial cells (HUVECs). METHODS: Cell viability and proliferation were assessed using cell counting kit-8 (CCK-8) assay and EdU assay. The apoptosis detection was performed by flow cytometry. Angiogenesis was evaluated through tube formation assay. The protein analysis was conducted via western blot. Inflammatory cytokines were examined by enzyme-linked immunosorbent assay (ELISA). The expression determination of circ_0124644, microRNA-370-3p (miR-370-3p) and forkhead box protein O4 (FOXO4) was performed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to analyze the interaction between targets. RESULTS: Treatment of ox-LDL resulted in the inhibition of cell viability, proliferation and angiogenesis but the promotion of apoptosis and inflammation in HUVECs. These ox-LDL-induced cell damages were alleviated after the downregulation of circ_0124644. Circ_0124644 interacted with miR-370-3p, and the regulatory role of circ_0124644 was associated with the sponge function of miR-370-3p. Additionally, miR-370-3p targeted FOXO4 and circ_0124644 increased the expression of FOXO4 through acting as a sponge of miR-370-3p. Overexpression of miR-370-3p protected from ox-LDL-induced injury via the downregulation of FOXO4. CONCLUSION: All results revealed that circ_0124644 accelerated endothelial injury in ox-LDL-treated HUVECs by mediating miR-370-3p-related FOXO4 expression.

Hsa_circ_0030042 Facilitates the Proliferation and Migration of Vascular Smooth Muscle Cells via the miR-514a-3p/FOXO1 Axis

PURPOSE

Circular RNA (circRNA) has been proved to play a vital role in atherosclerosis (AS) progression, and vascular smooth muscle cells (VSMCs) are involved in the progression of AS. However, the in-depth mechanism by which circRNA regulates VSMC proliferation and migration remains to be elusive.

METHODS

We used tumor necrosis factor-alpha (TNF-α) to treat VSMCs to establish a cell model of AS. We used Cell Counting Kit-8, terminal-deoxynucleoitidyl transferase-mediated nick end labeling, and transwell assays to assess the proliferation, apoptosis, and migration in TNF-α-induced VSMCs. Moreover, the interaction between molecules was measured by RNA-binding protein immunoprecipitation, RNA pull-down, and luciferase reporter assays.

RESULTS

Our study found that a novel circRNA hsa_circ_0030042, which is derived from its host gene forkhead box O1 (FOXO1), was upregulated in TNF-α-induced VSMCs. Silencing of hsa_circ_0030042 inhibited proliferation and migration while promoting apoptosis in TNF-α-induced VSMCs. Mechanically, hsa_circ_0030042 positively regulated FOXO1 expression via sponging miR-514a-3p.

CONCLUSIONS

Our study stated the vital role of the hsa_circ_0030042/miR-514a-3p/FOXO1 axis and provides a profound understanding about the circRNA in AS.

Circular RNA circCHFR downregulation protects against oxidized low-density lipoprotein-induced endothelial injury via regulation of microRNA-15b-5p/growth arrest and DNA damage inducible gamma

Atherosclerosis is the leading cause of coronary heart disease. In recent years, circ_0029589 (circCHFR) has been found to be associated with atherosclerosis development. However, the molecular mechanism of circCHFR action in atherosclerosis development is unknown. This study was aimed to investigate the function and action mechanism of circCHFR in atherosclerosis development. An atherosclerosis cell model was created by exposing human vascular endothelial cells (HUVECs) to oxidized low-density lipoprotein. The expression of circCHFR, microRNA(miR)-15b-5p, growth arrest and DNA damage inducible gamma (GADD45G), and their associated proteins was evaluated using quantitative reverse transcription-polymerase chain reaction and Western blotting. Additionally, cell viability, apoptosis, and cytokine levels were determined using Cell Counting Kit-8 (CCK8) assay, flow cytometry, and enzyme-linked immunosorbent assay, respectively. circCHFR expression was upregulated in patients with atherosclerosis and oxidized low-density lipoprotein (ox-LDL)-exposed HUVECs, whereas miR-15b-5p expression was downregulated. circCHFR silencing significantly improved viability and reduced apoptosis of HUVECs. In addition, the pro-apoptotic protein Bax and atherosclerosis-associated cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-α) were significantly downregulated, whereas the anti-apoptotic protein Bcl-2 was upregulated. Further, we discovered that circCHFR serves as a molecular sponge of miR-15b-5p. GADD45G was found to be an important target of miR-15b-5p; miR-15b-5p mimic inhibited GADD45G expression, reduced apoptosis and proinflammatory cytokine secretion, and improved cell survival. However, these effects of miR-15b-5p on (ox-LDL) induced HUVECs were reversed with GADD45G plasmid co-transfection. In conclusion, circCHFR promotes atherosclerosis progression via the miR-15b-5p/GADD45G axis and may be an important target for atherosclerosis treatment.

Circ_0057583 facilitates brain microvascular endothelial cell injury through modulating miR-204-5p/NR4A1 axis

Lipopolysaccharide (LPS) can induce vascular endothelial injury. Circular RNAs (circRNAs) have been verified to regulate different cellular processes in various diseases. This study intended to explore the potential role and mechanism of circ_0057583 in brain microvascular endothelial cell injury. Human brain microvascular endothelial cells (hBMECs) were exposed to different doses of LPS to induce cell damage. The levels of circ_0057583, microRNA-204-5p (miR-204-5p) and nuclear receptor 4A1 (NR4A1) were detected by quantitative real-time PCR or Western blot assays. Cell viability, apoptosis, inflammation and angiogenesis were assessed by Counting Kit-8 (CCK-8), flow cytometry, enzyme linked immunosorbent assay (ELISA) and tube formation assays. The targeting relationship between miR-204-5p and circ_0057583 or NR4A1 was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. LPS treatment elevated the expression of circ_0057583 and NR4A1, but decreased the expression of miR-204-5p in LPS-induced hBMECs. Downregulation of circ_0057583 abated LPS-induced hBMEC injury by inducing cell proliferation and angiogenesis, as well as inhibiting cell apoptosis, autophagy and inflammation. Circ_0057583 aggravated LPS-evoked hBMEC injury by regulating miR-204-5p. Also, miR-204-5p suppressed LPS-evoked hBMEC damage via targeting NR4A1. Moreover, circ_0057583 sponged miR-204-5p to up-regulate NR4A1 level. Depletion of circ_0057583 alleviated LPS-triggered brain microvascular endothelial endothelial cell injury through modulating miR-204-5p/NR4A1 axis.

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

Atherosclerosis is a fatal disorder that is fundamental to various cardiovascular diseases and severely threatens people’s health worldwide. Several studies have demonstrated the role of circular RNAs (circRNAs) in the pathogenesis of atherosclerosis. circUSP36 acts as a key modulator in the progression of atherosclerosis, but the molecular mechanism underlying this role is as yet unclear. This study aimed to elucidate the mechanism by which circUSP36 exerts its function in an in vitro cell model of endothelial cell dysfunction, which is one of pathological features of atherosclerosis. The circRNA traits of circUSP36 were confirmed, and we observed high expression of circUSP36 in endothelial cells exposed to oxidized low-density lipoprotein (ox-LDL). Functional assays revealed that overexpression of circUSP36 suppressed proliferation and migration of ox-LDL-treated endothelial cells. In terms of its mechanism, circUSP36 adsorbed miR-637 by acting as an miRNA sponge. Moreover, enhanced expression of miR-637 abated the impact of circUSP36 on ox-LDL-treated endothelial cell dysregulation. Subsequently, the targeting relationship between miR-637 and WNT4 was predicted using bioinformatics tools and was confirmed via luciferase reporter and RNA pull-down assays. Notably, depletion of WNT4 rescued circUSP36-mediated inhibition of endothelial cell proliferation and migration. In conclusion, circUSP36 regulated WNT4 to aggravate endothelial cell injury caused by ox-LDL by competitively binding to miR-637; this finding indicates circUSP36 to be a promising biomarker for the diagnosis and therapy of atherosclerosis.

CircSCAP aggravates oxidized low-density lipoprotein-induced macrophage injury by upregulating PDE3B via miR-221-5p in atherosclerosis

ABSTRACT

Atherosclerosis (AS) is a major risk factor for cardiovascular disease, in which circular RNAs (circRNAs) play important regulatory roles. This research aimed to explore the biological role of circSCAP (hsa_circ_0001292) in AS development. Real-time PCR or western blot assay was conducted to analyze RNA or protein expression. Cell proliferation and apoptosis were analyzed by CCK-8 assay and flow cytometry. The levels of lipid accumulation-associated indicators and oxidative stress factors were detected using commercial kits. The levels of inflammatory cytokines were examined using enzyme-linked immunosorbent assay (ELISA). Intermolecular interaction was verified via dual-luciferase reporter analysis or RNA pull-down analysis. CircSCAP and phosphodiesterase 3B (PDE3B) levels were elevated, whereas miR-221-5p level was decreased in AS patients and oxidized low-density lipoprotein (ox-LDL)-induced THP-1 cells. CircSCAP absence suppressed lipid deposition, inflammation, and oxidative stress in ox-LDL-induced THP-1 cells. MiR-221-5p was a target of circSCAP, and anti-miR-221-5p largely reversed si-circSCAP-induced effects in ox-LDL-induced THP-1 cells. PDE3B was a target of miR-221-5p, and PDE3B overexpression largely counteracted miR-221-5p accumulation-mediated effects in ox-LDL-induced THP-1 cells. NF-κB signaling pathway was regulated by circSCAP/miR-221-5p/PDE3B axis in ox-LDL-induced THP-1 cells. In conclusion, circSCAP facilitated lipid accumulation, inflammation, and oxidative stress in ox-LDL-induced THP-1 macrophages by regulating miR-221-5p/PDE3B axis.