CircRNA RSF1 regulated ox-LDL induced vascular endothelial cells proliferation, apoptosis and inflammation through modulating miR-135b-5p/HDAC1 axis in atherosclerosis

CircNRIP1 promotes proliferation, migration and phenotypic switch of Ang II-induced HA-VSMCs by increasing CXCL5 mRNA stability via recruiting IGF2BP1

Circular RNA (circRNA) has been found to be differentially expressed and involved in regulating the processes of human diseases, including thoracic aortic dissection (TAD). However, the role and mechanism of circNRIP1 in the TAD process are still unclear. GEO database was used to screen the differentially expressed circRNA and mRNA in type A TAD patients and age-matched normal donors. Angiotensin II (Ang II)-induced human aortic vascular smooth muscle cells (HA-VSMCs) were used to construct TAD cell models. The expression levels of circNRIP1, NRIP1, CXC-motif chemokine 5 (CXCL5) and IGF2BP1 were detected by quantitative real-time PCR. Cell proliferation and migration were determined by EdU assay, transwell assay and wound healing assay. The protein levels of synthetic phenotype markers, contractile phenotype markers, CXCL5 and IGF2BP1 were tested by western blot analysis. The interaction between IGF2BP1 and circNRIP1/CXCL5 was confirmed by RIP assay, and CXCL5 mRNA stability was assessed by actinomycin D assay. CircNRIP1 was upregulated in TAD patients and Ang II-induced HA-VSMCs. Knockdown of circNRIP1 suppressed Ang II-induced proliferation, migration and phenotypic switch of HA-VSMCs. Also, high expression of CXCL5 was observed in TAD patients, and its knockdown could inhibit Ang II-induced HA-VSMCs proliferation, migration and phenotypic switch. Moreover, CXCL5 overexpression reversed the regulation of circNRIP1 knockdown on Ang II-induced HA-VSMCs functions. Mechanistically, circNRIP1 could competitively bind to IGF2BP1 and subsequently enhance CXCL5 mRNA stability. CircNRIP1 might contribute to TAD progression by promoting CXCL5 mRNA stability via recruiting IGF2BP1.

A Review of MicroRNAs and lncRNAs in Atherosclerosis as Well as Some Major Inflammatory Conditions Affecting Atherosclerosis

It is generally accepted that atherosclerosis is a chronic inflammatory disease. The link between atherosclerosis and other inflammatory diseases such as psoriasis, type 2 diabetes mellitus (T2DM), and rheumatoid arthritis (RA) via metabolic, inflammatory, and immunoregulatory pathways is well established. The aim of our review was to summarize the associations between selected microRNAs (miRs) and long non-coding RNAs (lncRNAs) and atherosclerosis, psoriasis, T2DM, and RA. We reviewed the role of miR-146a, miR-210, miR-143, miR-223, miR-126, miR-21, miR-155, miR-145, miR-200, miR-133, miR-135, miR-221, miR-424, let-7, lncRNA-H19, lncRNA-MEG3, lncRNA-UCA1, and lncRNA-XIST in atherosclerosis and psoriasis, T2DM, and RA. Extracellular vesicles (EVs) are a method of intracellular signal transduction. Their function depends on surface expression, cargo, and the cell from which they originate. The majority of the studies that investigated lncRNAs and some miRs had relatively small sample sizes, which limits the generalizability of their findings and indicates the need for more research. Based on the studies reviewed, miR-146a, miR-155, miR-145, miR-200, miR-133, and lncRNA-H19 are the most promising potential biomarkers and, possibly, therapeutic targets for atherosclerosis as well as T2DM, RA, and psoriasis.

Kaempferol inhibits colorectal cancer metastasis through circ_0000345 mediated JMJD2C/β-catenin signalling pathway

BACKGROUND

Recurrence and metastasis are the main causes of disease deterioration in colorectal cancer (CRC) patients, yet efficient therapeutic strategies are lacking. Natural compounds for efficient antitumour therapeutics are becoming increasingly prominent. Kaempferol, one of the main components of flavonoids in plants, displays a variety of pharmacological activities. Our preliminary experiments suggested that kaempferol could inhibit CRC metastasis and is significantly associated with the β-catenin signalling pathway. Moreover, we also defined the regulatory roles of JMJD2C in β-catenin signalling in our previous work.

PURPOSE

This study aims to reveal the mechanism by which kaempferol inhibits CRC progression and regulates the JMJD2C/β-catenin signalling pathway.

METHODS

The migratory capabilities of CRC cells after kaempferol intervention were measured by scratch wound healing and transwell assays. Circ_0000345 knockdown CRC stable cell lines were generated by lentivirus infection. The possible mechanism of kaempferol on circ_0000345 was verified by molecular-protein docking and verification program cellular thermal shift assay (CETSA). A dual luciferase reporter gene assay was carried out for the targeting relationship among circ_0000345, miR-205-5p and JMJD2C. Fluorescence in situ hybridization (FISH) was performed to determine the expression of circ_0000345 in tumour tissues. A pulmonary metastatic model of CRC in vitro was built to assess the antimetastatic effect and mechanism of kaempferol in vivo.

RESULTS

In vitro, kaempferol inhibits the ability to migrate of CRC cells by reducing the activation of the JMJD2C/β-catenin signalling pathway. MiR-205-5p is a key bridge for kaempferol to inhibit the expression of JMJD2C. The function of miR-205-5p is impeded by circ_0000345, which shows higher expression levels in human metastatic CRC tissues than nonmetastatic CRC tissues, and its formation is regulated by the RNA-binding proteins HNRNPK and HNRNPL. Mechanistically, kaempferol physically interacts with HNRNPK and HNRNPL to suppress JMJD2C by downregulating the expression of circ_0000345. In vivo, kaempferol suppresses CRC lung metastasis. Kaempferol inhibits the activation of JMJD2C/β-catenin signalling through reducing the expression of circ_0000345 in the CRC lung metastasis model.

CONCLUSION

Circ_0000345 enhances activation of the JMJD2C/β-catenin signalling pathway through miR-205-5p to promote CRC metastasis. Kaempferol inhibits CRC metastasis through the circ_0000345-mediated JMJD2C/β-catenin signalling pathway, and this effect is influenced as a direct consequence of the binding of kaempferol with HNRNPK and HNRNPL. This provides promising therapeutic and/or adjuvant agents for advanced CRC and sheds light on the multifaceted role of phytomedicine in cancer.

Expanding roles of circRNAs in cardiovascular diseases

CircRNAs are a class of single-stranded RNAs characterized by covalently looped structures. Emerging advances have promoted our understanding of circRNA biogenesis, nuclear export, biological functions, and functional mechanisms. Roles of circRNAs in diverse diseases have been increasingly recognized in the past decade, with novel approaches in bioinformatics analysis and new strategies in modulating circRNA levels, which have made circRNAs the hot spot for therapeutic applications. Moreover, due to the intrinsic features of circRNAs such as high stability, conservation, and tissue-/stage-specific expression, circRNAs are believed to be promising prognostic and diagnostic markers for diseases. Aiming cardiovascular disease (CVD), one of the leading causes of mortality worldwide, we briefly summarize the current understanding of circRNAs, provide the recent progress in circRNA functions and functional mechanisms in CVD, and discuss the future perspectives both in circRNA research and therapeutics based on existing knowledge.

MiR-148a-3p/SIRT7 Axis Relieves Inflammatory-Induced Endothelial Dysfunction

In endothelial cells, miR-148a-3p is involved in several pathological pathways, including chronic inflammatory conditions. However, the molecular mechanism of miR-148a-3p in endothelial inflammatory states is, to date, not fully elucidated. To this end, we investigated the involvement of miR-148a-3p in mitochondrial dysfunction and cell death pathways in human aortic endothelial cells (teloHAECs) treated with interleukin-6 (IL-6), a major driver of vascular dysfunction. The results showed that during IL6-activated inflammatory pathways, including increased protein levels of sirtuin 7 (SIRT7) (p < 0.01), mitochondrial stress (p < 0.001), and apoptosis (p < 0.01), a decreased expression of miR-148a-3p was observed (p < 0.01). The employment of a miR-148a mimic counteracted the IL-6-induced cytokine release (p < 0.01) and apoptotic cell death (p < 0.01), and ameliorated mitochondria redox homeostasis and respiration (p < 0.01). The targeted relationship between miR-148a-3p and SIRT7 was predicted by a bioinformatics database analysis and validated via the dual-luciferase reporter assay. Mechanistically, miR-148a-3p targets the 3' untranslated regions of SIRT7 mRNA, downregulating its expression (p < 0.01). Herein, these in vitro results support the role of the miR-148a-3p/SIRT7 axis in counteracting mitochondrial damage and apoptosis during endothelial inflammation, unveiling a novel target for future strategies to prevent endothelial dysfunction.

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.

Research Progress on Histone Deacetylases Regulating Programmed Cell Death in Atherosclerosis

Histone deacetylases (HDACs) are epigenetic modifying enzyme that is closely related to chromatin structure and gene transcription, and numerous studies have found that HDACs play an important regulatory role in atherosclerosis disease. Apoptosis, autophagy and programmed necrosis as the three typical programmed cell death modalities that can lead to cell loss and are closely related to the developmental process of atherosclerosis. In recent years, accumulating evidence has shown that the programmed cell death mediated by HDACs is increasingly important in the pathophysiology of atherosclerosis. This paper first gives a brief overview of HDACs, the mechanism of programmed cell death, and their role in atherosclerosis, and then further elaborates on the role and mechanism of HDACs in regulating apoptosis, autophagy, and programmed necrosis in atherosclerosis, respectively, to provide new effective measures and theoretical basis for the prevention and treatment of atherosclerosis.

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.

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.

CircDLGAP4 induces autophagy and improves endothelial cell dysfunction in atherosclerosis by targeting PTPN4 with miR-134-5p

OBJECTIVE

Circular RNAs (circRNAs), a new subgroup of non-coding RNAs in the human transcriptome, are crucial in atherosclerosis (AS). Here, a newly identified circRNA circDLGAP4 was demonstrated to be downregulated in oxidized forms of low-density lipoprotein (ox-LDL)-induced HUVECs.

METHODS

This research adopted ox-LDL to stimulate human umbilical vein endothelial cells (HUVECs) to mimic AS in vitro. To further validate the protective action of circDLGAP4 in AS, a mouse model of AS was constructed with a high-fat diet. Functional assays evaluated circDLGAP4 role in AS in vitro and in vivo. Moreover, mechanism assays evaluated association of circDLGAP4/miR-134-5p/PTPN4.

RESULTS

CircDLGAP4 was induced to promote cell proliferative behavior and autophagy, inhibit apoptotic and inflammatory activities in ox-LDL-treated HUVECs, and attenuated endothelial barrier function. CircDLGAP4 regulated PTPN4 by directly targeting miR-134-5p. Meanwhile, inhibiting miR-134-5p reduced ox-LDL-induced cell dysfunction. Knockout of PTPN4 reversed circDLGAP4 overexpression or miR-134-5p downregulation in vitro. In addition, reducing circDLGAP4 or overexpressing miR-134-5p increased the red atherosclerotic plaque and lesion area of AS mice, reduced autophagy level, and promoted the release of inflammatory cytokines.

CONCLUSION

This study extends the role of circRNA in AS by inducing autophagy and improving endothelial dysfunction in AS via the circDLGAP4/miR-134-5p/PTPN4 axis.

Noncoding RNAs: Versatile regulators of endothelial dysfunction

Noncoding RNAs have recently emerged as versatile regulators of endothelial dysfunction in atherosclerosis, a chronic inflammatory disease characterized by the formation of plaques within the arterial walls. Through their ability to modulate gene expression, noncoding RNAs, including microRNAs, long noncoding RNAs, and circular RNAs, play crucial roles in various cellular processes involved in endothelial dysfunction (ECD), such as inflammation, pyroptosis, migration, proliferation, apoptosis, oxidative stress, and angiogenesis. This review provides an overview of the current understanding of the regulatory roles of noncoding RNAs in endothelial dysfunction during atherosclerosis. It highlights the specific noncoding RNAs that have been implicated in the pathogenesis of ECD, their target genes, and the mechanisms by which they contribute to ECD. Furthermore, we have reviewed the current therapeutics in atherosclerosis and explore their interaction with noncoding RNAs. Understanding the intricate regulatory network of noncoding RNAs in ECD may open up new opportunities for the development of novel therapeutic strategies to combat ECD.

Circ_0067934: a circular RNA with roles in human cancer

A circular RNA (circRNA) is a non-coding RNA (ncRNA) derived from reverse splicing from pre-mRNA and is characterized by the absence of a cap structure at the 5' end and a poly-adenylated tail at the 3' end. Owing to the development of RNA sequencing and bioinformatics approaches in recent years, the important clinical value of circRNAs has been increasingly revealed. Circ_0067934 is an RNA molecule of 170 nucleotides located on chromosome 3q26.2. Circ_0067934 is formed via the reverse splicing of exons 15 and 16 in PRKCI (protein kinase C Iota). Recent studies revealed the upregulation or downregulation of circ_0067934 in various tumors. The expression of circ_0067934 was found to be correlated with tumor size, TNM stage, and poor prognosis. Based on experiments with cancer cells, circ_0067934 promotes cancer cell proliferation, migratory activity, and invasion when overexpressed or downregulated. The potential mechanism involves the binding of circ_0067934 to microRNAs (miRNAs; miR-545, miR-1304, miR-1301-3p, miR-1182, miR-7, and miR-1324) to regulate the post-transcriptional expression of genes. Other mechanisms include inhibition of the Wnt/β-catenin and PI3K/AKT signaling pathways. Here, we summarized the biological functions and possible mechanisms of circ_0067934 in different tumors to enable further exploration of its translational applications in clinical diagnosis, therapy, and prognostic assessments.

Circular RNA sequencing identified circARNTL2 as a pathogenic factor in psoriasis by facilitating proliferation and cell cycle progression of keratinocytes

Psoriasis is a chronic recurrent skin disease, with excessive proliferation of keratinocytes. Recent studies indicated the pathogenic roles of circular RNA (circRNA) in psoriasis. Here, we screened the circRNA profiles from five psoriatic skin lesions and five normal skin tissues by circRNA sequencing and identified 1118 differentially expressed circRNAs (DECs) between psoriatic and normal groups. Among these DECs, high abundant circARNTL2 has been proven upregulated in psoriatic skin lesions by RT-qPCR assay. Then, the head-to-tail structure of circARNTL2 was validated by Sanger sequencing and RNase R digestion assay. Moreover, we determined cytoplastic location of circARNTL2 by RT-qPCR assay of nuclear/cytoplasmic RNA and FISH analysis. Further experiments demonstrated that silencing circARNTL2 expression could block cell proliferation and cell cycle progression of keratinocytes. Mechanistically, circARNTL2 can bind to and regulate Serpin B4 which also affects the proliferation of keratinocytes. These findings provide evidence for the role of circARNTL2 in psoriasis.

CircUSP10 promotes liver cancer progression by regulating miR-211-5p/TCF12/EMT signaling pathway

There is no precise diagnosis or prognosis for liver cancer (LC) using a single biomarker. Circular RNAs (circRNAs) contribute to the pathogenesis of different cancers, but their role in LC is not entirely understood. In this study, circUSP10, an aberrantly expressed circRNA in LC, was screened using the Gene Expression Omnibus database, and its tissue-specific expression was verified using qRT-PCR. In vitro, functional assays and nude mouse tumorigenesis models were used to investigate circUSP10 role in LC. RNA immunoprecipitation and dual-luciferase reporter assays were performed to study the mechanistic relationship between circUSP10, miR-211-5p, and transcription factor 12 (TCF12). We found that circUSP10 expression was upregulated in LC tissues and cells. CircUSP10 expression was linked to tumor size and tumor node metastasis stage and negatively correlated with LC prognosis. In vitro assays confirmed circUSP10-mediated proliferation, migration, and invasion of LC cells and their association with the epithelial-mesenchymal transition (EMT) pathway. Mechanistically, circUSP10 adsorbed miR-211-5p, which regulated TCF12 and promoted tumorigenesis via the EMT signaling pathway. Therefore, our results suggest that circUSP10 may promote LC progression by modulating the miR-211-5p/TCF12/EMT signaling cascade and may serve as a potential biomarker for LC diagnosis and prognosis.

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.

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.

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.

circACTA2 inhibits NLRP3 inflammasome-mediated inflammation via interacting with NF-κB in vascular smooth muscle cells

circACTA2 derived from the smooth muscle α-actin gene plays an important role in the regulation of vascular smooth muscle cell (VSMC) phenotype. The activation of NLRP3 inflammasome is involved in VSMC phenotypic switching. However, the mechanistic relationship between circACTA2 and NLRP3 inflammasome during vascular remodeling remains poorly understood. Here, we showed that circACTA2 was down-regulated in human intimal hyperplasia. circACTA2 overexpression in circACTA2 transgenic mice significantly decreased the neointimal hyperplasia induced by vascular injury, which is concomitant with a decrease in IL-18, IL-1β, TNF-α, and IL-6 levels. Gain- and loss-of-function studies revealed that circACTA2 alleviated VSMC inflammation by suppressing the activation of NLRP3 inflammasome. Mechanistically, circACTA2 inhibited the expression of NF-κB p65 and p50 subunits and interacted with p50, which impedes the formation of the p50/p65 heterodimer and nuclear translocation induced by TNF-α, thus resulting in the suppression of NLRP3 gene transcription and inflammasome activation. Furthermore, circACTA2 overexpression mitigated inflammation via repressing NLRP3 inflammasome-mediated VSMC pyroptosis. Importantly, employing a decoy oligonucleotide to compete with circACTA2 for binding to p50 could attenuate the expression of NLRP3, ASC, and caspase-1. These findings provide a novel insight into the functional roles of circACTA2 in VSMCs, and targeting the circACTA2-NF-κB-NLRP3 axis represents a promising therapeutic strategy for vascular remodeling.

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.

Regulation of NcRNA-protein binding in diabetic foot

Non-coding RNA (ncRNA) is a special type of RNA transcript that makes up more than 90 % of the human genome. Although ncRNA typically does not encode proteins, it indirectly controls a wide range of biological processes, including cellular metabolism, development, proliferation, transcription, and post-transcriptional modification. NcRNAs include small interfering RNA (siRNA), PIWI-interacting RNA (piRNA), tRNA-derived small RNA (tsRNA), etc. The most researched of these are miRNA, lncRNA, and circRNA, which are crucial regulators in the onset of diabetes and the development of associated consequences. The ncRNAs indicated above are linked to numerous diabetes problems by binding proteins, including diabetic foot (DF), diabetic nephropathy, diabetic cardiomyopathy, and diabetic peripheral neuropathy. According to recent studies, Mir-146a can control the AKAP12 axis to promote the proliferation and migration of diabetic foot ulcer (DFU) cells, while lncRNA GAS5 can activate HIF1A/VEGF pathway by binding to TAF15 to promote DFU wound healing. However, there are still many unanswered questions about the mechanism of action of ncRNAs. In this study, we explored the mechanism and new progress of ncRNA-protein binding in DF, which can provide help and guidance for the application of ncRNA in the early diagnosis and potential targeted intervention of DFU.

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.

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.

A review on the importance of miRNA-135 in human diseases

MicroRNA-135 (miR-135) is a microRNA which is involved in the pathoetiology of several neoplastic and non-neoplastic conditions. Both tumor suppressor and oncogenic roles have been reported for this miRNA. Studies in prostate, renal, gallbladder and nasopharyngeal cancers as well as glioma have shown down-regulation of miR-135 in cancerous tissues compared with controls. These studies have also shown the impact of miR-135 down-regulation on enhancement of cell proliferation and aggressive behavior. Meanwhile, miR-135 has been shown to be up-regulated in bladder, oral, colorectal and liver cancers. Studies in breast, gastric, lung and pancreatic cancers as well as head and neck squamous cell carcinoma have reported dual roles for miR-135. Dysregulation of miR-135 has also been noted in various non-neoplastic conditions such as Alzheimer’s disease, atherosclerosis, depression, diabetes, Parkinson, pulmonary arterial hypertension, nephrotic syndrome, endometriosis, epilepsy and allergic conditions. In the current review, we summarize the role of miR-135 in the carcinogenesis as well as development of other disorders.

HDAC1: an environmental sensor regulating endothelial function

The histone deacetylases (HDACs) are a family of enzymes that catalyse lysine deacetylation of both histone and non-histone proteins. Here, we review, summarize, and provide perspectives on the literature regarding one such HDAC, HDAC1, in endothelial biology. In the endothelium, HDAC1 mediates the effects of external and environmental stimuli by regulating major endothelial functions such as angiogenesis, inflammatory signalling, redox homeostasis, and nitric oxide signalling. Angiogenesis is most often, but not exclusively, repressed by endothelial HDAC1. The regulation of inflammatory signalling is more complex as HDAC1 promotes or suppresses inflammatory signalling depending upon the environmental stimuli. HDAC1 is protective in models of atherosclerosis where loss of HDAC1 results in increased cytokine and cell adhesion molecule (CAM) abundance. In other models, HDAC1 promotes inflammation by increasing CAMs and repressing claudin-5 expression. Consistently, from many investigations, HDAC1 decreases antioxidant enzyme expression and nitric oxide production in the endothelium. HDAC1 decreases antioxidant enzyme expression through the deacetylation of histones and transcription factors, and also regulates nitric oxide production through regulating both the expression and activity of nitric oxide synthase 3. The HDAC1-dependent regulation of endothelial function through the deacetylation of both histone and non-histone proteins ultimately impacts whole animal physiology and health.

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.