Circ_0068087 Silencing Ameliorates Oxidized Low-Density Lipoprotein-Induced Dysfunction in Vascular Endothelial Cells Depending on miR-186-5p-Mediated Regulation of Roundabout Guidance Receptor 1

LncRNA ZFAS1/miR-186-5p axis is involved in oxidative stress inhibition of myocardial ischemia-reperfusion injury by targeting BTG2

OBJECTIVE

To probe the involvement of long noncoding RNA zinc finger antisense 1 (ZFAS1)/microRNA (miR)-186-5p axis in inhibiting oxidative stress in myocardial ischemia-reperfusion injury (MIRI) by targeting B-cell translocation gene 2 (BTG2).

METHODS

The MIRI mice model was established by ligating the left anterior descending branch of the left coronary artery in C57BL/6 mice. The in vitro MIRI model was constructed by hypoxia and reoxygenation of HL-1 cardiomyocytes. Cardiomyocyte apoptosis and the extent of myocardial injury in mice were detected. The apoptosis rates, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in HL-1 cells were assessed. The relationship among ZFAS1, miR-186-5p, and BTG2 was verified.

RESULTS

High ZFAS1 and BTG2 levels and low miR-186-5p levels were demonstrated in I/R-injured myocardial tissues and in H/R-treated cardiomyocytes. Interference with ZFAS1 or elevation of miR-186-5p inhibited apoptosis and oxidative stress in H/R model cardiomyocytes and I/R-injured myocardial tissues. Overexpressing BTG2 impaired the ameliorative effects of miR-186-5p on MIRI. ZFAS1 negatively regulated miR-186-5p expression by acting as a molecular sponge. miR-186-5p targeted to regulate BTG2 negatively.

CONCLUSION

Interfering with ZFAS1 can upregulate miR-186-5p and thus inhibit BTG2 expression, thereby ameliorating MIRI.

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.

Circulating microRNA Profiles Identify a Patient Subgroup with High Inflammation and Severe Symptoms in Schizophrenia Experiencing Acute Psychosis

Schizophrenia is a complex and heterogenous psychiatric disorder. This study aimed to demonstrate the potential of circulating microRNAs (miRNAs) as a clinical biomarker to stratify schizophrenia patients and to enhance understandings of their heterogenous pathophysiology. We measured levels of 179 miRNA and 378 proteins in plasma samples of schizophrenia patients experiencing acute psychosis and obtained their Positive and Negative Syndrome Scale (PANSS) scores. The plasma miRNA profile revealed three subgroups of schizophrenia patients, where one subgroup tended to have higher scores of all the PANSS subscales compared to the other subgroups. The subgroup with high PANSS scores had four distinctively downregulated miRNAs, which enriched 'Immune Response' according to miRNA set enrichment analysis and were reported to negatively regulate IL-1β, IL-6, and TNFα. The same subgroup had 22 distinctively upregulated proteins, which enriched 'Cytokine-cytokine receptor interaction' according to protein set enrichment analysis, and all the mapped proteins were pro-inflammatory cytokines. Hence, the subgroup is inferred to have comparatively high inflammation within schizophrenia. In conclusion, miRNAs are a potential biomarker that reflects both disease symptoms and molecular pathophysiology, and identify a patient subgroup with high inflammation. These findings provide insights for the precision medicinal strategies for anti-inflammatory treatments in the high-inflammation subgroup of schizophrenia.

Circular RNAs: Regulators of endothelial cell dysfunction in atherosclerosis

Endothelial cell (EC) dysfunction is associated with atherosclerosis. Circular RNAs (circRNAs) are covalently closed loops formed by back-splicing, are highly expressed in a tissue-specific or cell-specific manner, and regulate ECs mainly through miRNAs (mircoRNAs) or protein sponges. This review describes the regulatory mechanisms and physiological functions of circRNAs, as well as the differential expression of circRNAs in aberrant ECs. This review focuses on their roles in inflammation, proliferation, migration, angiogenesis, apoptosis, senescence, and autophagy in ECs from the perspective of signaling pathways, such as nuclear factor κB (NF-κB), nucleotide-binding domain, leucine-rich-repeat family, pyrin-domain-containing 3 (NLRP3)/caspase-1, Janus kinase/signal transducer and activator of transcription (JAK/STAT), and phosphoinositide-3 kinase/protein kinase B (PI3K/Akt). Finally, we address the issues and recent advances in circRNAs as well as circRNA-mediated regulation of ECs to improve our understanding of the molecular mechanisms underlying the progression of atherosclerosis and provide a reference for studies on circRNAs that regulate EC dysfunction and thus affect atherosclerosis.

Circ_0068087 knockdown attenuates high-glucose-induced human tubular epithelial cell injury in a microribonucleic acid/progestin and adipoQ receptor 3-dependent manner in diabetic nephropathy

AIMS/INTRODUCTION

Previous studies have shown that circular ribonucleic acid mediates the occurrence of diabetic nephropathy. This study aimed to analyze the effects of circ_0068087 on high-glucose (HG)-induced human kidney 2 (HK2) cell dysfunction.

MATERIALS AND METHODS

Circ_0068087, miR-580-3p, and progestin and adipoQ receptor 3 (PAQR3) expression were detected by quantitative reverse transcription polymerase chain reaction. Cell viability and proliferation were investigated by Cell Counting Kit-8 and EdU assays, respectively. The cell apoptotic rate was assessed by flow cytometry. Inflammatory response was assessed by enzyme-linked immunoassays. Oxidative stress was evaluated by a superoxide dismutase activity assay kit and lipid peroxidation malondialdehyde assay kit. Molecular interaction was identified by dual-luciferase reporter assay.

RESULTS

Circ_0068087 and PAQR3 expression were significantly upregulated in diabetic nephropathy patients. HG treatment inhibited HK2 cell proliferation, but induced cell apoptosis, inflammation, oxidative stress and epithelial-mesenchymal transition by regulating circ_0068087. Circ_0068087 acted as a microribonucleic acid-580-3p (miR-580-3p) sponge, and miR-580-3p targeted PAQR3. Furthermore, circ_0068087 depletion repressed PAQR3 expression through miR-580-3p. MiR-580-3p inhibitors or PAQR3 introduction attenuated circ_0068087 silencing mediated-effects in HG-treated HK2 cells.

CONCLUSION

Circ_0068087 promoted HG-induced HK2 cell injuries by the regulation of the miR-580-3p/PAQR3 pathway.

LncRNA/CircRNA-miRNA-mRNA Axis in Atherosclerotic Inflammation: Research Progress

Atherosclerosis is characterized by chronic inflammation of the arterial wall. However, the exact mechanism underlying atherosclerosis-related inflammation has not been fully elucidated. To gain insight into the mechanisms underlying the inflammatory process that leads to atherosclerosis, there is need to identify novel molecular markers. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-protein-coding RNAs (lncRNAs) and circular RNAs (circRNAs) have gained prominence in recent years. LncRNAs/circRNAs act as competing endogenous RNAs (ceRNAs) that bind to miRNAs via microRNA response elements (MREs), thereby inhibiting the silencing of miRNA target mRNAs. Inflammatory mediators and inflammatory signaling pathways are closely regulated by ceRNA regulatory networks in atherosclerosis. In this review, we discuss the role of LncRNA/CircRNA-miRNA-mRNA axis in atherosclerotic inflammation and how it can be targeted for early clinical detection and treatment.

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 RNAs in vascular diseases

Vascular diseases are the leading cause of morbidity and mortality worldwide and are urgently in need of diagnostic biomarkers and therapeutic strategies. Circular RNAs (circRNAs) represent a unique class of RNAs characterized by a circular loop configuration and have recently been identified to possess a wide variety of biological functions. CircRNAs exhibit exceptional stability, tissue specificity, and are detectable in body fluids, thus holding promise as potential biomarkers. Their encoding function and stable gene expression also position circRNAs as an excellent alternative to gene therapy. Here, we briefly review the biogenesis, degradation, and functions of circRNAs. We summarize circRNAs discovered in major vascular diseases such as atherosclerosis and aneurysms, with a particular focus on molecular mechanisms of circRNAs identified in vascular endothelial cells and smooth muscle cells, in the hope to reveal new directions for mechanism, prognosis and therapeutic targets of vascular 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.

Extracellular vesicle-mediated transfer of lncRNA CLDN10-AS1 aggravates low-density lipoprotein-induced vascular endothelial injury

Oxidized low-density lipoprotein (ox-LDL) stimulation impairs the oxidation-reduction equilibrium in vascular endothelial cells (VECs) and contributes to atherosclerosis (AS). This study probed the mechanisms of extracellular vesicle (EV)-mediated transfer of lncRNA CLDN10 antisense RNA 1 (CLDN10-AS1) in ox-LDL-induced VEC injury. Initially, VEC injury models were established by treating human umbilical vein endothelial cells (HUVECs) with ox-LDL. EVs were isolated from HUVECs (HUVECs-EVs) and identified. CLDN10-AS1, microRNA (miR)-186, and Yin Yang 1 (YY1) expressions in ox-LDL-treated HUVECs and EVs derived from these cells (ox-EVs) were measured. HUVECs were incubated with EVs, after which the cell viability, apoptosis, and concentrations of proinflammatory cytokines and oxidative stress markers were measured. We discovered that CLDN10-AS1 and YY1 were upregulated in ox-LDL-treated HUVECs, whereas miR-186 was downregulated. ox-EVs treatment elevated CLDN10-AS1 expression in HUVECs and ox-EVs overexpressing CLDN10-AS1 promoted VEC injury. Besides, CLDN10-AS1 is competitively bound to miR-186 and promoted YY1 expression. Rescue experiments revealed that miR-186 overexpression or YY1 suppression partially reversed the roles of ox-EVs overexpressing CLDN10-AS1 in ox-LDL-induced VEC injury. Lastly, clinical serum samples were collected for verification. Overall, CLDN10-AS1 carried by HUVECs-EVs into HUVECs competitively bound to miR-186 to elevate YY1 expression, thereby aggravating ox-LDL-induced VEC injury.

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.

The mechanisms of glycolipid metabolism disorder on vascular injury in type 2 diabetes

Patients with diabetes have severe vascular complications, such as diabetic nephropathy, diabetic retinopathy, cardiovascular disease, and neuropathy. Devastating vascular complications lead to increased mortality, blindness, kidney failure, and decreased overall quality of life in people with type 2 diabetes (T2D). Glycolipid metabolism disorder plays a vital role in the vascular complications of T2D. However, the specific mechanism of action remains to be elucidated. In T2D patients, vascular damage begins to develop before insulin resistance and clinical diagnosis. Endothelial dysregulation is a significant cause of vascular complications and the early event of vascular injury. Hyperglycemia and hyperlipidemia can trigger inflammation and oxidative stress, which impair endothelial function. Furthermore, during the pathogenesis of T2D, epigenetic modifications are aberrant and activate various biological processes, resulting in endothelial dysregulation. In the present review, we provide an overview and discussion of the roles of hyperglycemia- and hyperlipidemia-induced endothelial dysfunction, inflammatory response, oxidative stress, and epigenetic modification in the pathogenesis of T2D. Understanding the connections of glucotoxicity and lipotoxicity with vascular injury may reveal a novel potential therapeutic target for diabetic vascular complications.

Circ_ROBO2/miR-186-5p/TRIM14 axis regulates oxidized low-density lipoprotein-induced cardiac microvascular endothelial cell injury

Background

Coronary artery disease (CAD) is one of the main risks of death, which is mainly caused by coronary arteries arteriosclerosis. Circular RNAs (circRNAs) have shown important regulatory roles in cardiovascular diseases. We amid to explore the role of circ_ROBO2 in CAD.

Methods

Cardiac microvascular endothelial cells (CMECs) stimulated by oxidized low-density lipoprotein (ox-LDL) were served as the cellular model of CAD. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot assay were performed to detect RNA levels and protein levels, respectively. Cell proliferation was assessed by 5-ethynyl-2′-deoxyuridine (EdU) assay and Cell Counting Kit-8 (CCK-8) assay. Flow cytometry was employed for measuring cell apoptosis. Matrigel tube formation assay was used to evaluate angiogenesis ability. The intermolecular interaction was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RNA-pull down assays.

Results

The expression of circ_ROBO2 was upregulated in CAD patients and ox-LDL-induced CMECs. Treatment of ox-LDL suppressed cell proliferation and angiogenic ability as well as promoted the apoptosis of CMECs partly by upregulating circ_ROBO2. MicroRNA-186-5p (miR-186-5p) was identified as a target of circ_ROBO2, and circ_ROBO2 knockdown attenuated ox-LDL-induced damage in CMECs by sponging miR-186-5p. Tripartite motif containing 14 (TRIM14) acted as a target of miR-186-5p, and TRIM14 overexpression alleviated miR-186-5p-mediated inhibitory effect on ox-LDL-induced injury in CMECs. Circ_ROBO2 positively regulated TRIM14 expression by sponging miR-186-5p.

Conclusion

Circ_ROBO2 played a promoting role in ox-LDL-induced CMECs injury by sponging miR-186-5p and regulating TRIM14, providing a promising treatment strategy for CAD.

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.