Circulating plasma circular RNAs as novel diagnostic biomarkers for congenital heart disease in children

Posttranscriptional Regulation by Proteins and Noncoding RNAs

Posttranscriptional regulation comprises those mechanisms occurring after the initial copy of the DNA sequence is transcribed into an intermediate RNA molecule (i.e., messenger RNA) until such a molecule is used as a template to generate a protein. A subset of these posttranscriptional regulatory mechanisms essentially are destined to process the immature mRNA toward its mature form, conferring the adequate mRNA stability, providing the means for pertinent introns excision, and controlling mRNA turnover rate and quality control check. An additional layer of complexity is added in certain cases, since discrete nucleotide modifications in the mature RNA molecule are added by RNA editing, a process that provides large mature mRNA diversity. Moreover, a number of posttranscriptional regulatory mechanisms occur in a cell- and tissue-specific manner, such as alternative splicing and noncoding RNA-mediated regulation. In this chapter, we will briefly summarize current state-of-the-art knowledge of general posttranscriptional mechanisms, while major emphases will be devoted to those tissue-specific posttranscriptional modifications that impact on cardiac development and congenital heart disease.

Transcriptome studies of congenital heart diseases: identifying current gaps and therapeutic frontiers

Congenital heart disease (CHD) are genetically complex and comprise a wide range of structural defects that often predispose to - early heart failure, a common cause of neonatal morbidity and mortality. Transcriptome studies of CHD in human pediatric patients indicated a broad spectrum of diverse molecular signatures across various types of CHD. In order to advance research on congenital heart diseases (CHDs), we conducted a detailed review of transcriptome studies on this topic. Our analysis identified gaps in the literature, with a particular focus on the cardiac transcriptome signatures found in various biological specimens across different types of CHDs. In addition to translational studies involving human subjects, we also examined transcriptomic analyses of CHDs in a range of model systems, including iPSCs and animal models. We concluded that RNA-seq technology has revolutionized medical research and many of the discoveries from CHD transcriptome studies draw attention to biological pathways that concurrently open the door to a better understanding of cardiac development and related therapeutic avenue. While some crucial impediments to perfectly studying CHDs in this context remain obtaining pediatric cardiac tissue samples, phenotypic variation, and the lack of anatomical/spatial context with model systems. Combining model systems, RNA-seq technology, and integrating algorithms for analyzing transcriptomic data at both single-cell and high throughput spatial resolution is expected to continue uncovering unique biological pathways that are perturbed in CHDs, thus facilitating the development of novel therapy for congenital heart disease.

Microarray Expression Profile and Bioinformatic Analysis of Circular RNA in Human Arteriosclerosis Obliterans

Background

Arteriosclerosis obliterans (ASO) is the leading cause of nontraumatic lower-extremity amputations. Multiple researches have suggested that circular RNAs (circRNAs) played vital regulatory functions in cancer and cardiovascular disease. Nevertheless, the underlying effect and pathological mechanism of circRNAs in the formation and progression of ASO are still indistinct.

Methods and Results

This study used microarray analysis to investigate the expression portrait of circRNAs in normal lower extremity arteries and ASO arteries. Bioinformatics analysis was conducted using the KEGG database to study the enrichment of differentially expressed circRNAs (DE circRNAs) and predict their functions. The accuracy of microarray assay was verified by evaluating expression of the top 5 upregulated and 5 downregulated circRNAs (raw density of normal group ≥200) using RT-qPCR. A circRNA-miRNA-mRNA interaction network was further predicted using software. Compared to the normal lower extremity group, the ASO arteries with HE and EVG staining presented hyperplastic fibrous membrane and luminal stenosis. A total of 12,735 circRNAs were identified, including 1196 DE circRNAs with 276 upregulated and 920 downregulated in ASO group based on |log2(FC)| > 1 and padj < 0.05. Among selected 10 circRNAs, RT-qPCR confirmed that hsa_circ_0003266, hsa_circ_0118936 and hsa_circ_0067161 were upregulated while hsa_circ_0091934 and hsa_circ_0092022 were downregulated in ASO group (p < 0.05). GO analysis presented that the DE circRNAs were primarily enriched in protein binding, intracellular part and organelle organization. KEGG pathway analysis indicated that MAPK signaling pathway, human T-cell leukemia virus 1 infection, proteoglycans in cancer were associated with the DE circRNAs. The circRNA-miRNA-mRNA interactive network revealed that both mRNAs and miRNAs linked to circRNAs played an indispensable role in ASO.

Conclusion

This study described the expression portrait of circRNAs in human ASO arteries, and revealed the molecular background for further investigations of the circRNA regulatory mechanism in the formation and progression of ASO.

Diagnosis of acute myocardial infarction using a combination of circulating circular RNA cZNF292 and clinical information based on machine learning

Circulating circular RNAs (circRNAs) are emerging as novel biomarkers for cardiovascular diseases (CVDs). Machine learning can provide optimal predictions on the diagnosis of diseases. Here we performed a proof-of-concept study to determine if combining circRNAs with an artificial intelligence approach works in diagnosing CVD. We used acute myocardial infarction (AMI) as a model setup to prove the claim. We determined the expression level of five hypoxia-induced circRNAs, including cZNF292, cAFF1, cDENND4C, cTHSD1, and cSRSF4, in the whole blood of coronary angiography positive AMI and negative non-AMI patients. Based on feature selection by using lasso with 10-fold cross validation, prediction model by logistic regression, and ROC curve analysis, we found that cZNF292 combined with clinical information (CM), including age, gender, body mass index, heart rate, and diastolic blood pressure, can predict AMI effectively. In a validation cohort, CM + cZNF292 can separate AMI and non-AMI patients, unstable angina and AMI patients, acute coronary syndromes (ACS), and non-ACS patients. RNA stability study demonstrated that cZNF292 was stable. Knockdown of cZNF292 in endothelial cells or cardiomyocytes showed anti-apoptosis effects in oxygen glucose deprivation/reoxygenation. Thus, we identify circulating cZNF292 as a potential biomarker for AMI and construct a prediction model "CM + cZNF292."

Novel circRNA-miRNA-mRNA networks regulated by maternal exercise in fetal hearts of pregestational diabetes

BACKGROUND

Maternal exercise lowers the incidence of congenital heart defects (CHDs) induced by pregestational diabetes. However, the molecular mechanisms underlying the beneficial effects of maternal exercise remain unclear. The present study aimed to identify circular RNA (circRNA), microRNA (miRNA) and mRNA networks that are regulated by maternal exercise in fetal hearts of pregestational diabetes.

METHODS

Pregestational diabetes was induced in adult C57BL/6 female mice by streptozotocin. The expression profiles of circRNAs, miRNAs and mRNAs in E10.5 fetal hearts of offspring of control and diabetic mothers with or without exercise were analyzed using next generation sequencing. circRNA-miRNA-mRNA networks in fetal hearts were mapped and key candidate transcripts were verified by qPCR analysis.

RESULTS

Pregestational diabetes dysregulated the expression of 206 circRNAs, 66 miRNAs and 391 mRNAs in fetal hearts. Maternal exercise differentially regulated 188 circRNAs, 57 miRNAs and 506 mRNAs in fetal hearts of offspring of pregestational diabetes. A total of 5 circRNAs, 12 miRNAs, and 28 mRNAs were incorporated into a final maternal exercise-associated regulatory network in fetal hearts of offspring of maternal diabetes. Notably, maternal exercise normalized the dysregulated circ_0003226/circ_0015638/miR-351-5p and circ_0002768/miR-3102-3p.2-3p pairs in fetal hearts of pregestational diabetes.

CONCLUSION

Maternal exercise reverses the dysregulated circ_0003226/circ_0015638/miR-351-5p and circ_0002768/miR-3102-3p.2-3p pairs, and partially normalizes circRNA, miRNA, and mRNA expression profiles in fetal hearts of pregestational diabetes. These findings shed new light on the potential mechanisms of the beneficial effects of maternal exercise on the developing heart in diabetic pregnancies.

The expression profiles of circular RNAs and competing endogenous RNA networks in intrahepatic cholangiocarcinoma

Introduction: Intrahepatic cholangiocarcinoma (iCCA) is a heterogeneous entity with diverse etiologies, morphologies, and clinical outcomes, but our knowledge of its epidemiology and carcinogenesis is very limited. Materials and methods: The expression patterns of circRNAs were explored in iCCA tissues and corresponding adjacent normal ones, denoted by (iCCA) and (iCCAP), respectively, using high-throughput sequencing. Results: A total of 117 differential expressed (DE) circRNAs were identified. Based on the parental transcripts of circRNAs, these DE circRNAs were related to several important GO terms and were enriched in important pathways. Two circRNA-mediated ceRNA networks were constructed and many important metabolic pathways related to mRNAs were regulated by DE circRNAs via miRNAs. Conclusion: Our study revealed the DE circRNAs in the iCCA tissues compared with iCCAP ones, suggesting that circRNAs may play crucial roles in the pathogenesis of iCCA.

Circular RNA circ-RCCD promotes cardiomyocyte differentiation in mouse embryo development via recruiting YY1 to the promoter of MyD88

Congenital heart disease (CHD) is the most common birth defect, affecting approximately 1% of live births. Genetic and environmental factors are leading factors to CHD, but the mechanism of CHD pathogenesis remains unclear. Circular RNAs (circRNAs) are kinds of endogenous non‐coding RNAs (ncRNAs) involved in a variety of physiological and pathological processes, especially in heart diseases. In this study, three significant differently expressed circRNA between maternal embryonic day (E) E13 and E17 was found by microarray assay. Among them, the content of circ‐RCCD increases with the development of heart and was enriched in primary cardiomyocytes of different species, which arouses our attention. Functional experiments revealed that inhibition of circ‐RCCD dramatically suppressed the formation of beating cell clusters, the fluorescence intensity of cardiac differentiation marker MF20, and the expression of the myocardial‐specific markers CTnT, Mef2c, and GATA4. Next, we found that circ‐RCCD was involved in cardiomyocyte differentiation through negative regulation of MyD88 expression. Further experiments proved that circ‐RCCD inhibited MyD88 levels by recruiting YY1 to the promoter of MyD88; circ‐RCCD inhibited nuclear translocation of YY1. These results reported that circ‐RCCD promoted cardiomyocyte differentiation by recruiting YY1 to the promoter of MyD88. And, this study provided a potential role and molecular mechanism of circ‐RCCD as a target for the treatment of CHD.

Amniotic Fluid microRNA in Severe Twin-Twin Transfusion Syndrome Cardiomyopathy-Identification of Differences and Predicting Demise

Twin-twin transfusion syndrome (TTTS) is a rare but serious cause of fetal cardiomyopathy with poorly understood pathophysiology and challenging prognostication. This study sought a nonbiased, comprehensive assessment of amniotic fluid (AF) microRNAs from TTTS pregnancies and associations of these miRNAs with clinical characteristics. For the discovery cohort, AF from ten fetuses with severe TTTS cardiomyopathy were selected and compared to ten normal singleton AF. Array panels assessing 384 microRNAs were performed on the discovery cohort and controls. Using a stringent q < 0.0025, arrays identified 32 miRNAs with differential expression. Top three microRNAs were miR-99b, miR-370 and miR-375. Forty distinct TTTS subjects were selected for a validation cohort. RT-PCR targeted six differentially-expressed microRNAs in the discovery and validation cohorts. Expression differences by array were confirmed by RT-PCR with high fidelity. The ability of these miRNAs to predict clinical differences, such as cardiac findings and later demise, was evaluated on TTTS subjects. Down-regulation of miRNA-127-3p, miRNA-375-3p and miRNA-886 were associated with demise. Our results indicate AF microRNAs have potential as a diagnostic and prognostic biomarker in TTTS. The top microRNAs have previously demonstrated roles in angiogenesis, cardiomyocyte stress response and hypertrophy. Further studies of the mechanism of actions and potential targets is warranted.

Circular RNA hsa_circ_105039 promotes cardiomyocyte differentiation by sponging miR‑17 to regulate cyclinD2 expression

Previously it was found that hsa_circ_105039 was underexpressed in the heart tissue of patients with congenital heart disease (CHD). However, the function and mechanism of hsa_circ_105039 in CHD are unclear. In the present study, induced pluripotent stem (iPS) cells were differentiated into cardiomyocytes using 1% dimethyl sulfoxide (DMSO). Cell differentiation, viability, migration and apoptosis were measured before and following hsa_circ_105039 knockdown or overexpression. The results indicated that hsa_circ_105039 overexpression promoted cell differentiation, viability and migration; whereas apoptosis was simultaneously repressed. A luciferase reporter assay verified that hsa_circ_105039 acted as a sponge for microRNA (miR)‑17 and that cyclinD2 was a direct target of miR‑17. Furthermore, differentiation‑related genes and proteins were analyzed by reverse transcription‑quantitative PCR and western blotting, respectively. The results showed that hsa_circ_105039 could also upregulate the expression of differentiation‑related genes and proteins, including natriuretic peptide A, cardiac troponin I, GATA‑binding protein 4 and homobox transcription factor, in iPS cells. The results suggested that hsa_circ_105039 exerted a protective effect by promoting miR‑17/cyclinD2 in DMSO‑induced iPS cardiomyocytes, which indicated that hsa_circ_105039 is a potential key molecule for the diagnosis of CHD.

CircRNA Hsa_circ_0001017 Inhibited Gastric Cancer Progression via Acting as a Sponge of miR-197

BACKGROUND

Gastric cancer (GC) is one of the most common digestive system diseases and yet lacks effective therapeutic regimen.

AIMS

The aim of our present research was to probe the value of hsa_circ_0001017 in GC treatment.

METHODS

qRT-PCR and Western blot were performed to detect gene and protein expressions, respectively. CCK-8 assay and clone formation assay were used to ensure the proliferation of GC cell lines. Transwell assay was performed to measure the migration and invasion of GC cell lines. The relationship between hsa_circ_0001017 and miR-197 and that between miR-197 and RHOB 3'-UTR were ensured using the luciferase reporter assay.

RESULTS

Decreased hsa_circ_0001017 was discovered in GC, and upregulation of hsa_circ_0001017 notably repressed proliferation, migration, and invasion of GC cell lines. We further certificated that hsa_circ_0001017 served as miR-197 sponge and suppressed the expression of miR-197. Moreover, hsa_circ_0001017 upregulation meaningfully accelerated RHOB expression in both gene and protein levels, and RHOB was a downstream target of miR-197. Overexpression of miR-197 could markedly restrain hsa_circ_0001017-induced RHOB increasing and stifle inhibition of hsa_circ_0001017 to the malignant phenotype of GC cell lines. Next, our results further confirmed that hsa_circ_0001017 increasing notably inhibited tumor growth, impeded miR-197 production, while it enhanced the expression of RHOB in vivo.

CONCLUSION

Our data demonstrated that upregulation of hsa_circ_0001017 could notably muffle the proliferation as well as the metastasis of GC cell lines and impede the formation of GC tumor via targeting to miR-197/RHOB signaling pathway. Our results evidenced that hsa_circ_0001017 may act as a rising biomarker for GC treatment.

Circular RNAs as novel potential biomarkers for pancreatic cancer

Pancreatic cancer (PaCa) is the fourth leading cause of cancer-related deaths in the United States, and the vast majority of these malignancies are pancreatic ductal adenocarcinomas (PDAC), but there is still a lack of early detection biomarkers for PaCa. Unlike linear RNAs, circRNAs form covalently closed continuous loops and can act as mammalian gene regulators. They may be diagnostic or predictive biomarkers for some tumors, also be novel potential therapeutic targets in different diseases. This review focuses on (1) the biogenesis of circRNAs, RNA binding proteins (RBPs) and complementary sequences of circRNAs; (2) the characteristics of circRNAs which allow them to interact with miRNAs; (3) the roles of circRNAs playing in the regulation of gene expression, cell behavior and cancer, and their potential role as novel biomarkers and therapeutic targets in pancreatic cancer.

Circular RNAs hsa-circ0000175 and hsa-circ0044235 in plasma are novel biomarkers for new-onset rheumatoid arthritis

Circular RNAs (circRNAs) are a class of non-coding RNAs that could serve as potential molecular markers for disease diagnosis. However, the role of circRNAs in plasma from new-onset rheumatoid arthritis (RA) has not been extensively investigated. In this study, the expression of hsa-circ0000175 and hsa-circ0044235 in plasma from RA patients, healthy controls (HCs), systemic lupus erythematosus (SLE) patients, osteoarthritis (OA), and undiagnosed arthritis (UA) patients were determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Correlation analysis was used to assess the correlation of the two circRNAs and clinical variables of RA. The receiver operating characteristic (ROC) curves were created to evaluate the diagnostic value and multivariate analysis (logistic regression) was performed to analyse the risk factors. We confirmed that hsa-circ0000175 was significantly elevated in plasma from patients with new-onset RA compared with HC and patients with new-onset SLE, but significantly was reduced when compared with OA + UA patients. Hsa-circ0044235 was found to be significantly decreased in plasma from patients with new-onset RA compared with HC and OA + UA patients, but was significantly increased compared with SLE patients. The expression of plasma hsa-circ0000175 in new-onset RA patients was associated with platelet count (PLT), plateletcrit (PCT), and platelet large cell ratio (PLR), the expression of plasma hsa-circ0044235 new-onset RA patients was associated with swollen joint count (SJC), painful joint count (PJC), and disease activity score 28 (DAS28). ROC curve analysis suggested that the combination of hsa-circ0000175 and hsa-circ0044235 has some value in the diagnosis of new-onset RA from HC, patients with SLE and patients with OA + UA. The logistic regression analysis revealed that the expression of hsa-circ0000175 and hsa-circ0044235 in plasma were risk factors for RA. This study suggests that the combination of plasma hsa-circ0000175 and hsa-circ0044235 improves the diagnostic accuracy for new-onset RA. Moreover, the expression levels of plasma hsa-circ0000175 and hsa-circ0044235 were associated with disease activity and severity of RA.

Identification and comparison of circular RNAs in preeclampsia

Background

Preeclampsia (PE) is a pregnancy-specific syndrome, belongs to the gestational hypertension diseases category and is considered among the causes of maternal and perinatal mortality and morbidity. However, the pathogenesis of PE is still vague.

Methods

In the present study, the circular RNA (circRNA) expression patterns of normal pregnant women and PE patients were investigated using whole RNA sequencing.

Results

A total of 151 differential expressed circRNAs were identified including 121 upregulated and 30 downregulated ones. Functional and pathway enrichment analysis was conducted on the differentially expressed circRNAs using Gene Ontology and KEGG databases. The results of this analysis indicated that several crucial biological processes and pathways were enriched in PE patients. circRNA–microRNA (miRNA) interaction analysis indicated that the reported differentially expresse circRNAs may be associated with some regulatory functions through miRNAs in PE patients. Two ceRNAs networks were constructed according to the targeting relationship between circRNAs/miRNAs and miRNAs/mRNAs. One sub-network contained one upregulated circRNA, four downregulated miRNAs and five upregulated mRNAs, and another sub-network contained 10 downregulated circRNAs, 21 upregulated miRNAs and 15 downregulated mRNAs.

Conclusion

CircRNA expression patterns have been investigated and this analysis revealed their potential regulatory mechanisms in PE patients. We constructed the ceRNAs (competing endogenous RNA) to reveal the potential molecular roles of dysregulated circRNAs in the PE patients using RNA sequencing data. circRNA_13301 was the only one upregulated circRNA in ceRNA being targeted by four miRNAs.

The Role of Epigenetics in Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect among newborns worldwide and contributes to significant infant morbidity and mortality. Owing to major advances in medical and surgical management, as well as improved prenatal diagnosis, the outcomes for these children with CHD have improved tremendously so much so that there are now more adults living with CHD than children. Advances in genomic technologies have discovered the genetic causes of a significant fraction of CHD, while at the same time pointing to remarkable complexity in CHD genetics. For this reason, the complex process of cardiogenesis, which is governed by multiple interlinked and dose-dependent pathways, is a well investigated process. In addition to the sequence of the genome, the contribution of epigenetics to cardiogenesis is increasingly recognized. Significant progress has been made dissecting the epigenome of the heart and identified associations with cardiovascular diseases. The role of epigenetic regulation in cardiac development/cardiogenesis, using tissue and animal models, has been well reviewed. Here, we curate the current literature based on studies in humans, which have revealed associated and/or causative epigenetic factors implicated in CHD. We sought to summarize the current knowledge on the functional role of epigenetics in cardiogenesis as well as in distinct CHDs, with an aim to provide scientists and clinicians an overview of the abnormal cardiogenic pathways affected by epigenetic mechanisms, for a better understanding of their impact on the developing fetal heart, particularly for readers interested in CHD research.

A narrative review of the roles of the miR-15/107 family in heart disease: lessons and prospects for heart disease

Heart disease is one of the leading causes of morbidity and mortality globally. To reduce morbidity and mortality among patients with heart disease, it is important to identify drug targets and biomarkers for more effective diagnosis, prognosis, and treatment. MicroRNAs (miRNAs) are characterized as a group of endogenous, small non-coding RNAs, which function by directly inhibiting target genes. The miR-15/107 family is a group of evolutionarily conserved miRNAs comprising 10 members that share an identical motif of AGCAGC, which determines overlapping target genes and cooperation in the biological process. Accumulating evidence has demonstrated the predominant dysregulation of the miR-15/107 family in cardiovascular disease, neurodegenerative disease, and cancer. In this review, we summarize the current understanding of the miR-15/107 family, focusing on its role in the regulation in the development of the heart and the progression of heart disease. We also discuss the potential of different members of the miR-15/107 family as biomarkers for diverse heart disease, as well as the current applications and challenges in the use of the miR-15/107 family in clinical trials for various disease. This paper hopes to explore the potential of the miR-15/107 family as therapeutic targets or biomarkers and to provide directions for future research.

Circular RNAs in childhood-related diseases and cancers: A review

Research into the diagnosis, treatment and prevention of childhood-related diseases is the key to reducing their morbidity and mortality. Circular RNAs (circRNAs) play critical roles, both in physiology and pathology, and there is ample evidence to show that they play varying roles in tissue development and gene regulation. Studies on circRNAs in different childhood-related diseases have confirmed their great potential for disease prevention and treatment. These breakthroughs highlight the pathological role of circRNAs in cancers, as well as cardiovascular and hereditary childhood illnesses. In this review, we summarize the role of circRNAs in childhood-related diseases and cancer, and provide an update of the possible diagnostic and therapeutic application of circRNAs.

Non-Coding RNAs as Blood-Based Biomarkers in Cardiovascular Disease

In 2020, cardiovascular diseases (CVDs) remain a leading cause of mortality and morbidity, contributing to the burden of the already overloaded health system. Late or incorrect diagnosis of patients with CVDs compromises treatment efficiency and patient's outcome. Diagnosis of CVDs could be facilitated by detection of blood-based biomarkers that reliably reflect the current condition of the heart. In the last decade, non-coding RNAs (ncRNAs) present on human biofluids including serum, plasma, and blood have been reported as potential biomarkers for CVDs. This paper reviews recent studies that focus on the use of ncRNAs as biomarkers of CVDs.

Circular RNAs in Cardiac Regeneration: Cardiac Cell Proliferation, Differentiation, Survival, and Reprogramming

Circular RNAs (circRNAs) are classified as long non-coding RNAs (lncRNAs) that are characterized by a covalent closed-loop structure. This closed-loop shape is the result of a backsplicing event in which the 3' and 5' splice sites are ligated. Through the lack of 3' poly(A) tails and 5' cap structures, circRNAs are more stable than linear RNAs because these adjustments make the circular loop less susceptible to exonucleases. The majority of identified circRNAs possess cell- and tissue-specific expression patterns. In addition, high-throughput RNA-sequencing combined with novel bioinformatics algorithms revealed that circRNA sequences are often conserved across different species suggesting a positive evolutionary pressure. Implicated as regulators of protein turnover, micro RNA (miRNA) sponges, or broad effectors in cell differentiation, proliferation, and senescence, research of circRNA has increased in recent years. Particularly in cardiovascular research, circRNA-related discoveries have opened the door for the development of potential diagnostic and therapeutic tools. Increasing evidence links deviating circRNA expression patterns to various cardiovascular diseases including ischemic heart failure. In this mini-review, we summarize the current state of knowledge on circRNAs in cardiac regeneration with a focus on cardiac cell proliferation, differentiation, cardiomyocyte survival, and cardiac reprogramming.

Circular RNAs: Functions and Clinical Significance in Cardiovascular Disease

Cardiovascular disease (CVD) causes high morbidity and mortality worldwide. Accumulating research has indicated the possible roles played by circular RNAs (circRNAs) in the pathogenesis of CVD. CircRNAs are non-coding RNAs with covalently closed loop structures. CircRNAs can function by acting as miRNA sponges, RNA binding protein sponges, mRNA transcriptional regulators and templates for protein translation. The specific characteristics of circRNAs such as high stability, abundant distribution, and tissue- and developmental stage-specific expression make them potential biomarkers for the diagnosis and prognosis of CVD. In this paper, we systematically summarized the current knowledge regarding the biogenesis, biological properties and the action mechanisms of circRNAs, elucidated the roles played by circRNAs in the pathogenesis of CVD, and explored the diagnostic potential of circRNAs in CVD. With in-depth studies, an increasing number of molecular mechanisms underlying the participation of circRNAs in CVD may be elucidated, and the application of circRNAs in the clinical diagnosis and prevention of CVD may eventually be realized.

Circular RNAs: Promising Molecular Biomarkers of Human Aging-Related Diseases via Functioning as an miRNA Sponge

Circular RNAs (circRNAs) are a new class of noncoding single-stranded RNAs that differ from linear microRNAs (miRNAs), since they form covalently closed loop structures without free 3′ poly(A) tails or 5′ caps. circRNAs are the competitive endogenous RNAs (ceRNAs) by binding to miRNA through miRNA response elements (MREs) (i.e., “miRNA sponge”), thereby reducing the quantity of miRNA available to target mRNA, subsequently promoting mRNA stability or protein expression, which involves the initiation and progress of human diseases. Owing to these features of abundance, stability, conservative property, and tissue and stage specificity, widely distributing in the extracellular space and in various bodily fluids, circRNAs can be considered as potential biomarkers for various diseases. Here, we reviewed the promising circRNAs being disease biomarkers, focused on their regulatory function by acting as miRNA sponges, and described their roles in cancer, cardiovascular or neurodegenerative diseases, osteoarthritis, rheumatoid arthritis, diabetes, and other human aging-related diseases, which provide a new direction for pathogenesis, diagnosis, and treatment of human aging-related diseases.

Circulating plasma circular RNAs as novel diagnostic biomarkers for congenital heart disease in children

Objective

The diagnostic value of circulating circular RNAs (circRNAs) has received more and more attention. However, little has been reported about their potential in the diagnosis of congenital heart diseases (CHD). In this study, we explored differential expression of circRNAs from children with CHD to evaluate their potential as clinical biomarkers.

Methods

We established a discovery cohort (four CHD cases; four matched healthy controls) and a validation cohort (40 CHD cases; 40 matched healthy controls). Microarray expression analysis was performed on the discovery set to identify candidate circRNAs. Candidates were further validated in the validation set. The diagnostic accuracy of circRNAs was determined by receiver operating characteristic (ROC) analysis. Gene ontology (GO), pathway, and network analysis were performed to predict a network of circRNA/miRNA and target mRNAs related to CHD.

Results

The top seven significantly differentially expressed CHD‐associated circRNAs were validated by RT‐PCR as follows: hsa_circRNA_004183, hsa_circRNA_079265, hsa_circRNA_105039, hsa_circRNA_404686, hsa_circRNA_101050, hsa_circRNA_100787, and hsa_circRNA_101328. Three significantly down‐regulated circRNAs (hsa_circRNA_004183, hsa_circRNA_079265, and hsa_circRNA_105039) were identified with area under curve (AUC) values of 0.758, 0.809, and 0.907, respectively; the combination had an AUC of 0.965. An interaction network was constructed by 43 circRNAs, 9 miRNAs, and 29 mRNAs, which involved in heart development.

Conclusions

We identified three circRNAs under‐expressed in plasma from children with CHD. These circRNAs may be crucial in the development of CHD and may serve as novel non‐invasive biomarkers for the diagnosis of CHD in children.