Altered long non-coding RNA expression profile in rabbit atria with atrial fibrillation: TCONS_00075467 modulates atrial electrical remodeling by sponging miR-328 to regulate CACNA1C

Progress of circRNA/lncRNA-miRNA-mRNA axis in atrial fibrillation

Atrial fibrillation (AF) is a prevalent arrhythmia that requires effective biomarkers and therapeutic targets for clinical management. In recent years, non-coding RNAs (ncRNAs) have emerged as key players in the pathogenesis of AF, particularly through the ceRNA (competitive endogenous RNA) mechanism. By acting as ceRNAs, ncRNAs can competitively bind to miRNAs and modulate the expression of target mRNAs, thereby influencing the biological behavior of AF. The ceRNA axis has shown promise as a diagnostic and prognostic biomarker for AF. This review provides a comprehensive overview of the roles of ncRNAs in the development and progression of AF, highlighting the intricate crosstalk between different ncRNAs in AF pathophysiology. Furthermore, we discuss the potential implications of targeting the circRNA/lncRNA-miRNA-mRNA axis for the diagnosis, prognosis, and therapeutic intervention of AF.

The roles of long noncoding RNAs in atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia that often occurs in patients with structural heart disease and is a significant cause of morbidity and mortality in clinical settings. AF is typically associated with significant changes of both the structure of the atria and the cardiac conduction system. AF can result in reduced heart function, heart failure, and various other complications. Current drug therapy for AF patients is often ineffective and may have adverse effects. Radiofrequency ablation is more effective than traditional drug therapy, but this invasive procedure carries potential risks and may lead to postoperative recurrence, limiting the clinical benefits to some extent. Therefore, in-depth research into the molecular mechanisms of AF and exploration of new treatment strategies based on research findings are prerequisites for improving the treatment of AF and the associated cardiac conditions. Long noncoding RNAs (lncRNAs) are a new class of noncoding RNA (ncRNAs) with a length exceeding 200 nt, which regulate gene expression at multiple levels. Increasing evidence suggests that lncRNAs participate in many pathological processes of AF initiation, development, and maintenance, such as structural remodeling, electrical remodeling, renin-angiotensin system anomalies, and intracellular calcium deregulation s. LncRNAs that play key roles in structural and electrical remodeling may become molecular markers and targets for AF diagnosis and treatment, respectively, while lncRNAs critical to autonomic nervous system remodeling may bring new insights into the prognosis and recurrence of AF. This review article provides a synopsis on the up-to-date research findings relevant to the roles of lncRNAs in AF.

New drug discovery of cardiac anti-arrhythmic drugs: insights in animal models

Cardiac rhythm regulated by micro-macroscopic structures of heart. Pacemaker abnormalities or disruptions in electrical conduction, lead to arrhythmic disorders may be benign, typical, threatening, ultimately fatal, occurs in clinical practice, patients on digitalis, anaesthesia or acute myocardial infarction. Both traditional and genetic animal models are: In-vitro: Isolated ventricular Myocytes, Guinea pig papillary muscles, Patch-Clamp Experiments, Porcine Atrial Myocytes, Guinea pig ventricular myocytes, Guinea pig papillary muscle: action potential and refractory period, Langendorff technique, Arrhythmia by acetylcholine or potassium. Acquired arrhythmia disorders: Transverse Aortic Constriction, Myocardial Ischemia, Complete Heart Block and AV Node Ablation, Chronic Tachypacing, Inflammation, Metabolic and Drug-Induced Arrhythmia. In-Vivo: Chemically induced arrhythmia: Aconitine antagonism, Digoxin-induced arrhythmia, Strophanthin/ouabain-induced arrhythmia, Adrenaline-induced arrhythmia, and Calcium-induced arrhythmia. Electrically induced arrhythmia: Ventricular fibrillation electrical threshold, Arrhythmia through programmed electrical stimulation, sudden coronary death in dogs, Exercise ventricular fibrillation. Genetic Arrhythmia: Channelopathies, Calcium Release Deficiency Syndrome, Long QT Syndrome, Short QT Syndrome, Brugada Syndrome. Genetic with Structural Heart Disease: Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia, Dilated Cardiomyopathy, Hypertrophic Cardiomyopathy, Atrial Fibrillation, Sick Sinus Syndrome, Atrioventricular Block, Preexcitation Syndrome. Arrhythmia in Pluripotent Stem Cell Cardiomyocytes. Conclusion: Both traditional and genetic, experimental models of cardiac arrhythmias' characteristics and significance help in development of new antiarrhythmic drugs.

Long Non-coding RNA Involved in the Pathophysiology of Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is a prevalent and chronic cardiovascular disorder associated with various pathophysiological alterations, including atrial electrical and structural remodeling, disrupted calcium handling, autonomic nervous system dysfunction, aberrant energy metabolism, and immune dysregulation. Emerging evidence suggests that long non-coding RNAs (lncRNAs) play a significant role in the pathogenesis of AF.

OBJECTIVE

This discussion aims to elucidate the involvement of AF-related lncRNAs, with a specific focus on their role as miRNA sponges that modulate crucial signaling pathways, contributing to the progression of AF. We also address current limitations in AF-related lncRNA research and explore potential future directions in this field. Additionally, we summarize feasible strategies and promising delivery systems for targeting lncRNAs in AF therapy.

CONCLUSION

In conclusion, targeting AF-related lncRNAs holds substantial promise for future investigations and represents a potential therapeutic avenue for managing AF.

Dissecting the Molecular Mechanisms Driving Electropathology in Atrial Fibrillation: Deployment of RNA Sequencing and Transcriptomic Analyses

Despite many efforts to treat atrial fibrillation (AF), the most common progressive and age-related cardiac tachyarrhythmia in the Western world, the efficacy is still suboptimal. A plausible reason for this is that current treatments are not directed at underlying molecular root causes that drive electrical conduction disorders and AF (i.e., electropathology). Insights into AF-induced transcriptomic alterations may aid in a deeper understanding of electropathology. Specifically, RNA sequencing (RNA-seq) facilitates transcriptomic analyses and discovery of differences in gene expression profiles between patient groups. In the last decade, various RNA-seq studies have been conducted in atrial tissue samples of patients with AF versus controls in sinus rhythm. Identified differentially expressed molecular pathways so far include pathways related to mechanotransduction, ECM remodeling, ion channel signaling, and structural tissue organization through developmental and inflammatory signaling pathways. In this review, we provide an overview of the available human AF RNA-seq studies and highlight the molecular pathways identified. Additionally, a comparison is made between human RNA-seq findings with findings from experimental AF model systems and we discuss contrasting findings. Finally, we elaborate on new exciting RNA-seq approaches, including single-nucleotide variants, spatial transcriptomics and profiling of different populations of total RNA, small RNA and long non-coding RNA.

Research progress of non-coding RNA in atrial fibrillation

Atrial fibrillation (AF) is a common arrhythmia in clinic, and its incidence is increasing year by year. In today's increasingly prevalent society, ageing poses a huge challenge to global healthcare systems. AF not only affects patients' quality of life, but also causes thrombosis, heart failure and other complications in severe cases. Although there are some measures for the diagnosis and treatment of AF, specific serum markers and targeted therapy are still lacking. In recent years, ncRNAs have become a hot topic in cardiovascular disease research. These ncRNAs are not only involved in the occurrence and development of AF, but also in pathophysiological processes such as myocardial infarction and atherosclerosis, and are potential biomarkers of cardiovascular diseases. We believe that the understanding of the pathophysiological mechanism of AF and the study of diagnosis and treatment targets can form a more systematic diagnosis and treatment framework of AF and provide convenience for individuals with AF and the society.

Long Noncoding RNA UCA1 Correlates With Electropathology in Patients With Atrial Fibrillation

BACKGROUND

Perpetuation of atrial fibrillation (AF) is rooted in derailment of molecular proteostasis pathways that cause electrical conduction disorders that drive AF. Emerging evidence indicates a role for long noncoding RNAs (lncRNAs) in the pathophysiology of cardiac diseases, including AF.

OBJECTIVES

In the present study, the authors explored the association between 3 cardiac lncRNAs and the degree of electropathology.

METHODS

Patients had paroxysmal AF (ParAF) (n = 59), persistent AF (PerAF) (n = 56), or normal sinus rhythm without a history of AF (SR) (n = 70). The relative expression levels of urothelial carcinoma-associated 1 (UCA1), OXCT1-AS1 (SARRAH), and the mitochondrial lncRNA uc022bqs.q (LIPCAR) were measured by means of quantitative reverse-transcription polymerase chain reaction in the right atrial appendage (RAA) or serum (or both). A selection of the patients was subjected to high-resolution epicardial mapping to evaluate electrophysiologic features during SR.

RESULTS

The expression levels of SARRAH and LIPCAR were decreased in RAAs of all AF patients compared with SR. Also, in RAAs, UCA1 levels significantly correlated with the percentage of conduction block and delay, and inversely with conduction velocity, indicating that UCA1 levels in RAA reflect the degree of electrophysiologic disorders. Moreover, in serum samples, SARRAH and UCA1 levels were increased in the total AF group and ParAF patients compared with SR.

CONCLUSIONS

LncRNAs SARRAH and LIPCAR are reduced in RAA of AF patients, and UCA1 levels correlate with electrophysiologic conduction abnormalities. Thus, RAA UCA1 levels may aid staging of electropathology severity and act as a patient-tailored bioelectrical fingerprint.

Non-coding RNAs in human health and disease: potential function as biomarkers and therapeutic targets

Human diseases have been a critical threat from the beginning of human history. Knowing the origin, course of action and treatment of any disease state is essential. A microscopic approach to the molecular field is a more coherent and accurate way to explore the mechanism, progression, and therapy with the introduction and evolution of technology than a macroscopic approach. Non-coding RNAs (ncRNAs) play increasingly important roles in detecting, developing, and treating all abnormalities related to physiology, pathology, genetics, epigenetics, cancer, and developmental diseases. Noncoding RNAs are becoming increasingly crucial as powerful, multipurpose regulators of all biological processes. Parallel to this, a rising amount of scientific information has revealed links between abnormal noncoding RNA expression and human disorders. Numerous non-coding transcripts with unknown functions have been found in addition to advancements in RNA-sequencing methods. Non-coding linear RNAs come in a variety of forms, including circular RNAs with a continuous closed loop (circRNA), long non-coding RNAs (lncRNA), and microRNAs (miRNA). This comprises specific information on their biogenesis, mode of action, physiological function, and significance concerning disease (such as cancer or cardiovascular diseases and others). This study review focuses on non-coding RNA as specific biomarkers and novel therapeutic targets.

Progress in molecular biology and translational science: Epigenetics in cardiovascular health and disease

Conrad Waddington's epigenetics landscape has provided a metaphorical framework for how cells progress from undifferentiated states to one of several discrete, distinct, differentiated cell fates. The understanding of epigenetics has evolved over time, with DNA methylation being the most studied epigenetic modification, followed by histone modifications and non-coding RNA. Cardiovascular diseases (CVD) are leading contributors to death worldwide, with the prevalence of CVDs increasing across the last couple of decades. Significant amount of resources being poured into researching key mechanisms and underpinnings of the various CVDs. These molecular studies looked at the genetics, epigenetics as well as the transcriptomics of various cardiovascular conditions, aiming to provide mechanistic insights. It has paved the way for therapeutics to be developed and in recent years, epi-drugs for the treatment of CVDs. This chapter aims to cover the various roles of epigenetics in the context of cardiovascular health and disease. The following will be examined in detail: the developments in basic experimental techniques used to study epigenetics, the role of epigenetics in various CVDs (hypertension, atrial fibrillation, atherosclerosis, and heart failure), and current advances in epi-therapeutics, providing a holistic view of the current concerted efforts in advancing the field of epigenetics in CVDs.

DNA Methylation Alterations in Fractionally Irradiated Rats and Breast Cancer Patients Receiving Radiotherapy

Radiation-Induced CardioVascular Disease (RICVD) is an important concern in thoracic radiotherapy with complex underlying pathophysiology. Recently, we proposed DNA methylation as a possible mechanism contributing to RICVD. The current study investigates DNA methylation in heart-irradiated rats and radiotherapy-treated breast cancer (BC) patients. Rats received fractionated whole heart X-irradiation (0, 0.92, 6.9 and 27.6 Gy total doses) and blood was collected after 1.5, 3, 7 and 12 months. Global and gene-specific methylation of the samples were evaluated; and gene expression of selected differentially methylated regions (DMRs) was validated in rat and BC patient blood. In rats receiving an absorbed dose of 27.6 Gy, DNA methylation alterations were detected up to 7 months with differential expression of cardiac-relevant DMRs. Of those, SLMAP showed increased expression at 1.5 months, which correlated with hypomethylation. Furthermore, E2F6 inversely correlated with a decreased global longitudinal strain. In BC patients, E2F6 and SLMAP exhibited differential expression directly and 6 months after radiotherapy, respectively. This study describes a systemic radiation fingerprint at the DNA methylation level, elucidating a possible association of DNA methylation to RICVD pathophysiology, to be validated in future mechanistic studies.

Animal Models to Study Cardiac Arrhythmias

Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide, accounting for 10% to 15% of all deaths. Although most arrhythmias are due to acquired heart disease, inherited channelopathies and cardiomyopathies disproportionately affect children and young adults. Arrhythmogenesis is complex, involving anatomic structure, ion channels and regulatory proteins, and the interplay between cells in the conduction system, cardiomyocytes, fibroblasts, and the immune system. Animal models of arrhythmia are powerful tools for studying not only molecular and cellular mechanism of arrhythmogenesis but also more complex mechanisms at the whole heart level, and for testing therapeutic interventions. This review summarizes basic and clinical arrhythmia mechanisms followed by an in-depth review of published animal models of genetic and acquired arrhythmia disorders.

Serum exosomal long non-coding RNAs as a diagnostic biomarker for atrial fibrillation

BACKGROUND

Exosomal long non-coding RNAs (lncRNAs) are known as ideal diagnostic biomarkers of various diseases. However, there are no reports on the use of serum exosomal lncRNAs as diagnostic biomarkers for atrial fibrillation (AF).

OBJECTIVE

The purpose of this study was to explore serum exosomal lncRNAs as a useful tool for diagnosing AF.

METHODS

First, serum exosomes from patients with persistent AF and controls were isolated using a polymer-based exosome precipitation kit. Next, we conducted a multi-phase process including screening and two independent validation phases. In the screening phase, serum exosomal lncRNA expression profiles were examined using RNA-sequencing analysis. In two validation phases, we evaluated the expression levels of candidate exosomal lncRNAs using qRT-PCR. Finally, we performed different statistical and functional analyses.

RESULTS

After the screening phase, we identified 26 differentially expressed lncRNAs (i.e., 15 up-regulated and 11 down-regulated lncRNAs with a |fold change| ≥ 2 and p < 0.05) in serum exosomes from patients with persistent AF compared with the controls. We then screened out six exosomal lncRNAs as biomarker candidates following parameters: read length ≥ 200 nucleotides; exon number ≥ 2; and coding potential score < 0.1. In two validation phases, exosomal lncRNAs LOC105377989 and LOC107986997 were consistently up-regulated in serum of patients with persistent AF, compared with the controls (p < 0.0001). Moreover, both exosomal lncRNAs exhibited significant diagnostic validity for AF. Notably, exosomal lncRNA LOC107986997 was involved in AF-related pathophysiological mechanisms.

CONCLUSION

Serum-derived exosomal lncRNA LOC107986997 could serve as a potential biomarker for AF diagnosis.

Upregulated miR-328-3p and its high risk in atrial fibrillation: A systematic review and meta-analysis with meta-regression

BACKGROUND

Several studies have shown miR-328-3p increased in atrial fibrillation (AF), but some researches indicated no difference or even decreased. This inconsistent result confuses researchers, and it is urgent to know the truth. This study is to assess the association between miR-328-3p levels in plasma/atrial tissue and patients with AF.

METHODS

PubMed, EMBASE, Scopus, Web of Science, and ProQuest were searched from inception to February 1, 2021. The standardized mean differences (SMD) with their 95% confidence interval (CI) were calculated to evaluate the association between miR-328-3p levels and AF.

RESULTS

Twelve studies met the inclusion criteria and were used for our meta-analysis. Overall, the levels of miR-328-3p were higher in patients with AF than in the control group (SMD = 0.69, 95% CI [0.10, 1.28], P = .022). After adjustment, the overall SMD was 0.82 (95% CI [0.22, 1.42], P = .007). Sensitivity analysis indicated that the results were stable, and the trim-fill analysis showed that the results were credible. Subgroup analyses showed that AF patients, n ≥ 30, various of comorbidity, articles published earlier, and Asia groups had higher levels of expression of miR-328-3p.

CONCLUSIONS

High levels of miR-328-3p are significantly associated with an increased risk of AF. It implies that miR-328-3p played an important role in diagnosis and may serve as a potential momentous, and useful biomarker to identify AF.

Research Progress of LncRNAs in Atrial Fibrillation

Atrial fibrillation (AF) is one of the most common arrhythmias in adults, with high morbidity and increased mortality risk. In recent years, the clinical diagnosis, treatment, and mechanistic research of AF have increased exponentially, and regulation based on the potential molecular mechanism of AF is a research hotspot. Long noncoding RNAs (LncRNAs), usually refer to noncoding RNA transcripts greater than 200 nucleotides in length, have been shown to play a role in cardiovascular diseases such as coronary artery disease, heart failure, and myocardial fibrosis through various regulatory methods. An increasing number of researchers have begun to pay attention to the identification and function of LncRNAs in AF. This article reviews changes in the expression of related LncRNAs detected in AF and describes the LncRNAs that play a regulatory role in AF-related processes, to explore the potential of LncRNAs as new biomarkers and therapeutic targets in AF.

Epigenetic Mechanism and Therapeutic Implications of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia attacking 1. 5–2.0% of general population worldwide. It has a significant impact on morbidity and mortality globally and its prevalence increases exponentially with age. Therapies like catheter ablation or conventional antiarrhythmic drugs have not provided effective solution to the recurrence for AF over the past decades. Over 100 genetic loci have been discovered to be associated with AF by Genome-wide association studies (GWAS) but none has led to a therapy. Recently potential involvement of epigenetics (DNA methylation, histone modification, and non-coding RNAs) in the initiation and maintenance of AF has partly emerged as proof-of-concept in the mechanism and management of AF. Here we reviewed the epigenetic features involved in AF pathophysiology and provided an update of their implications in AF therapy.

Study on the role and mechanism of lncRNA in the remodeling of atrial energy metabolism in rabbits with atrial fibrillation based on nano sensor technology

The purpose is to reveal the role and mechanism of long non-coding ribonucleic acid (lncRNA) in atrial fibrillation (AF) and atrial energy metabolism remodeling. The healthy adult New Zealand rabbit was chosen as the experimental animal, and the AF rabbit models were built. Besides, the lncRNA sequencing method based on nano sensor technology was employed to detect the differentially expressed lncRNAs, and the target lncRNA and its target genes were determined through bioinformatics analysis. Subsequently, TCONS_00016478 dysfunction experiment was performed. The gene level and protein level of TCONS_00016478, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), and its downstream genes were detected. The results show that after sequencing, 99,755 new lncRNAs transcripts are found in total, of which 1,215 are significantly differentially expressed, 974 are down-regulated, and 241 are up-regulated. A new transcript TCONS_00016478 associated with the remodeling of atrial energy metabolism is further screened. Silencing TCONS_00016478 can significantly reduce PGC1-α, PPARγ, GLUT4, and CPT1 expression levels (P < 0.05). Thereby, TCONS_00016478 can affect the atrial energy metabolism remodeling and atrial fibrillation in experimental rabbits by regulating the PGC1-α/PPARγ signaling pathway.

Exosomes and Exosomal Non-coding RNAs Are Novel Promises for the Mechanism-Based Diagnosis and Treatments of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia worldwide and has a significant impact on human health and substantial costs. Currently, there is a lack of accurate biomarkers for the diagnosis and prognosis of AF. Moreover, the long-term efficacy of the catheter ablation in the AF is unsatisfactory. Therefore, it is necessary to explore new biomarkers and treatment strategies for the mechanism-based AF. Exosomes are nano-sized biovesicles released by nearly all types of cells. Since the AF would be linked to the changes of the atrial cells and their microenvironment, and the AF would strictly influence the exosomal non-coding RNAs (exo-ncRNAs) expression, which makes them as attractive diagnostic and prognostic biomarkers for the AF. Simultaneously, the exo-ncRNAs have been found to play an important role in the mechanisms of the AF and have potential therapeutic prospects. Although the role of the exo-ncRNAs in the AF is being actively investigated, the evidence is still limited. Furthermore, there is a lack of consensus regarding the most appropriate approach for exosome isolation and characterization. In this article, we reviewed the new methodologies available for exosomes biogenesis, isolation, and characterization, and then discussed the mechanism of the AF and various levels and types of exosomes relevant to the AF, with the special emphasis on the exo-ncRNAs in the diagnosis, prognosis, and treatment of the mechanism-based AF.

A narrative review of non-coding RNAs in atrial fibrillation: potential therapeutic targets and molecular mechanisms

Objective

This review summarizes the advances in the study of ncRNAs and atrial remodeling mechanisms to explore potential therapeutic targets and strategies for AF.

Background

Atrial fibrillation (AF) is one of the most common arrhythmias, and its morbidity and mortality rates are gradually increasing. Non-coding ribonucleic acid RNAs (ncRNAs) are transcribed from the genome and do not have the ability to be translated into proteins. A growing body of evidence has shown ncRNAs are extensively involved in the pathophysiological processes underlying AF. However, the precise molecular mechanisms of these associations have not been fully elucidated. Atrial remodeling plays a key role in the occurrence and development of AF, and includes electrical remodeling, structural remodeling, and autonomic nerve remodeling. Research has shown that ncRNA expression is altered in the plasma and tissues of AF patients that mediate cardiac excitation and arrhythmia, and is closely related to atrial remodeling.

Methods

Literatures about ncRNAs and atrial fibrillation were extensively reviewed to discuss and analyze.

Conclusions

The biology of ncRNAs represents a relatively new field of research and is still in an emerging stage. Recent studies have laid a foundation for understanding the molecular mechanisms of AF, future studies aimed at identifying how ncRNAs act on atrial fibrillation to provide potentially promising therapeutic targets for the treatment of atrial fibrillation.

lncRNA KCNQ1OT1 may function as a competitive endogenous RNA in atrial fibrillation by sponging miR‑223‑3p

Atrial fibrillation (AF) is one of the most common forms of cardiac arrhythmia. Novel evidence has indicated that a competing endogenous RNA (ceRNA) mechanism may occur in AF. The present study aimed to identify differentially expressed microRNAs (miRNAs/miRs) in AF and predict their targeting long non-coding RNAs (lncRNAs) to identify a potential ceRNA network involved in AF using bioinformatics analysis. The GSE68475 microarray dataset was downloaded from the Gene Expression Omnibus database and differentially expressed miRNAs in AF were obtained. In addition, right atrial appendage (RAA) tissues from patients with AF were collected to determine the expression levels of the miRNAs identified following bioinformatics analysis using reverse transcription-quantitative PCR (n=8 per group). Subsequently, Gene Ontology (GO) functional term and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analyses of the target genes of differentially expressed miRNAs of interest were performed. The potential upstream lncRNAs targeting the identified miRNAs were predicted using bioinformatics analysis. A dual luciferase reporter assay was used to verify the existence of a targeted relationship between the differentially expressed miRNA and lncRNA of interest. The results identified 43 differentially expressed miRNAs, including 23 upregulated miRNAs. The trends in the expression levels of miR-223-3p were inconsistent between the microarray data and those recorded in the RAA tissues from patients with persistent AF. Therefore, miR-223-3p was selected as the miRNA of interest for further investigations. The target gene of miR-233-3p was found to be enriched in 57 GO terms and 21 KEGG signaling pathways. According to the bioinformatics prediction, 69 lncRNAs targeting miR-223-3p were identified, including the lncRNA growth arrest-specific transcript 5, lncRNA KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1) and lncRNA MYC-induced long non-coding RNA. The results from dual luciferase assay confirmed that miR-223-3p was a direct target of KCNQ1OT1. A ceRNA regulatory relationship may exist between KCNQ1OT1 and miR-223-3p in AF, providing therefore a novel potential research target for further studies.

Role of long non-coding RNAs in adipogenesis: State of the art and implications in obesity and obesity-associated diseases

Obesity is an evolutionary, chronic, and relapsing disease that consists of a pathological accumulation of adipose tissue able to increase morbidity for high blood pressure, type 2 diabetes, metabolic syndrome, and obstructive sleep apnea in adults, children, and adolescents. Despite intense research over the last 20 years, obesity remains today a disease with a complex and multifactorial etiology. Recently, long non-coding RNAs (lncRNAs) are emerging as interesting new regulators as different lncRNAs have been found to play a role in early and late phases of adipogenesis and to be implicated in obesity-associated complications onset. In this review, we discuss the most recent advances on the role of lncRNAs in adipocyte biology and in obesity-associated complications. Indeed, more and more researchers are focusing on investigating the underlying roles that these molecular modulators could play. Even if a significant number of evidence is correlation-based, with lncRNAs being differentially expressed in a specific disease, recent works are now focused on deeply analyzing how lncRNAs can effectively modulate the disease pathogenesis onset and progression. LncRNAs possibly represent new molecular markers useful in the future for both the early diagnosis and a prompt clinical management of patients with obesity.

Transcriptional factors in calcium mishandling and atrial fibrillation development

Healthy cardiac conduction relies on the coordinated electrical activity of distinct populations of cardiomyocytes. Disruption of cell-cell conduction results in cardiac arrhythmias, a leading cause of morbidity and mortality worldwide. Recent genetic studies have highlighted a major heritable component and identified numerous loci associated with risk of atrial fibrillation, including transcription factor genes, particularly those important in cardiac development, microRNAs, and long noncoding RNAs. Identification of such genetic factors has prompted the search to understand the mechanisms that underlie the genetic component of AF. Recent studies have found several mechanisms by which genetic alterations can result in AF formation via disruption of calcium handling. Loss of developmental transcription factors in adult cardiomyocytes can result in disruption of SR calcium ATPase, sodium calcium exchanger, calcium channels, among other ion channels, which underlie action potential abnormalities and triggered activity that can contribute to AF. This review aims to summarize the complex network of transcription factors and their roles in calcium handling.

Functional genomics and epigenomics of atrial fibrillation

Atrial fibrillation is a progressive cardiac arrhythmia that increases the risk of hospitalization and adverse cardiovascular events. Despite years of study, we still do not have a full comprehension of the molecular mechanism responsible for the disease. The recent implementation of large-scale approaches in both patient samples, population studies and animal models has helped us to broaden our knowledge on the molecular drivers responsible for AF and on the mechanisms behind disease progression. Understanding genomic and epigenomic changes that take place during chronification of AF will prove essential to design novel treatments leading to improved patient care.

MicroRNA-328-5p Alleviates Macrophage Lipid Accumulation through the Histone Deacetylase 3/ATP-binding cassette transporter A1 pathway

MicroRNA-328 (miR-328) was reported to protect against atherosclerosis, but its role in foam cell formation remains unknown. The aim of this study was to investigate the effect of miR-328-5p on macrophage lipid accumulation and the underlying mechanisms. The results showed that miR-328-5p expression was robustly decreased in oxidized low-density lipoprotein (ox-LDL)-treated macrophages. Treatment of human acute monocytic leukemia cel (THP-1) macrophage-derived foam cells with a miR-328-5p mimic markedly increased [³ H]-cholesterol efflux, inhibited lipid droplet accumulation, and decreased intracellular total cholesterol (TC), free cholesterol (FC) and cholesteryl ester (CE) contents. Upregulation of miR-328-5p also reduced the expression of histone deacetylase 3 (HDAC3) but increased the levels of ATP-binding cassette transporter A1 (ABCA1) in THP-1 macrophage-derived foam cells. Mechanistically, miR-328-5p inhibited HDAC3 expression by directly targeting its 3'UTR, thereby promoting ABCA1 expression and the subsequent cholesterol efflux. Furthermore, miR-328-5p mimic treatment did not affect the uptake of Dil-ox-LDL or the expression of scavenger receptor-A (SR-A), thrombospondin receptor (CD36) and ABCG1. Taken together, these findings suggest that miR-328-5p alleviates macrophage lipid accumulation through the HDAC3/ABCA1 pathway.

Long Noncoding RNA HOTAIR Functions as a Competitive Endogenous RNA to Regulate Connexin43 Remodeling in Atrial Fibrillation by Sponging MicroRNA-613

Several studies have indicated that long noncoding RNAs (lncRNAs)-HOX transcript antisense RNA (HOTAIR) is involved in some cardiovascular diseases by regulating gene expression as a competitive endogenous RNA (ceRNA). GJA1 encoding Cx43 is one potential target gene of microRNA-613 (miR-613). Meanwhile, there is a potential target regulatory relationship between HOTAIR and miR-613. The present study is aimed at investigating whether HOTAIR functions as a ceRNA to regulate the Cx43 expression in atrial fibrillation (AF) by sponging miR-613. The expressions of HOTAIR, miR-613, and Cx43 were detected in the right atrial appendages of 45 patients with heart valve disease, including 23 patients with chronic AF. The HOTAIR overexpressed and underexpressed HL-1 cell model were constructed to confirm the effect of HOTAIR on Cx43. Then, the Cx43 expression was detected to testify the interplay between HOTAIR and miR-613 after cotransfecting HOTAIR and miR-613. Furthermore, luciferase assays were performed to verify that HOTAIR could regulate Cx43 remolding as a ceRNA by sponging miR-613. The expression of HOTAIR and Cx43 was significantly downregulated in chronic AF group. HOTAIR regulated positively the Cx43 expression in HL-1 cells. The upregulated effect of HOTAIR on the Cx43 expression could be remarkably attenuated by miR-613. Moreover, the inhibitory effect of miR-613 on the Cx43 expression could be obviously mitigated by HOTAIR. At last, luciferase assays confirmed HOTAIR functioned as a ceRNA in the Cx43 expression by sponging miR-613. Our study suggests that HOTAIR, functioning as a ceRNA by sponging miR-613, is an important contributor to Cx43 remolding in AF.

The functions of LncRNA in the heart

Cardiovascular disease is a major cause of death and disability worldwide. Recently, increasing evidence has demonstrated that various lncRNAs play critical roles in the pathogenesis of cardiovascular diseases, including myocardial ischemia and reperfusion (I/R) injury. LncRNAs are transcripts longer than 200 nucleotides. They are considered a class of dynamic noncoding RNAs known to be involved in physiological and pathological conditions with regulatory and structural roles in numerous biological processes, including genomic imprinting, epigenetic regulation, cell proliferation, development, aging and apoptosis. They are emerging as potential key regulators of a variety of cardiovascular diseases. However, the roles of lncRNAs in the heart function remain largely unknown. The purpose of this review was to summarize the functions of lncRNAs in the heart and discuss the challenges and possible strategies of lncRNA research for cardiovascular disease.

Long noncoding RNA TCONS-00106987 promotes atrial electrical remodelling during atrial fibrillation by sponging miR-26 to regulate KCNJ2

Long noncoding RNAs (lncRNAs) have been suggested to play indispensable roles in multiple heart diseases. However, the correlations between lncRNAs and atrial fibrillation (AF) are unclear. In this study, we performed comprehensive lncRNA profiling via high-throughput RNA sequencing analysis using non-AF and AF rabbit models. Based on a series of filtering pipelines and bioinformatics analyses, TCONS-00106987 was selected for further research. TCONS-00106987 levels were increased in the atria during AF. Moreover, the atrial effective refractory period was shortened and the AF inducibility was increased in vivo in response to lentiviral-mediated up-regulation of TCONS-00106987. TCONS-00106987 repression resulted in the opposite effects. Further studies indicated that TCONS-00106987 expression was positively correlated with the expression of the protein-coding gene KCNJ2. Luciferase reporter assays and whole-cell patch-clamp recording confirmed that TCONS-00106987 promoted electrical remodelling via endogenous competition with microRNA-26 (miR-26) to induce transcription of its target gene KCNJ2, thereby increasing inward-rectifier K⁺ current (I_K1 ). In conclusion, our study reveals a pathogenic lncRNA-miRNA regulatory network specific to atrial electrical remodelling that offers potential therapeutic targets for AF.

Genetics and Epigenetics of Atrial Fibrillation

Atrial fibrillation (AF) is known to be the most common supraventricular arrhythmia affecting up to 1% of the general population. Its prevalence exponentially increases with age and could reach up to 8% in the elderly population. The management of AF is a complex issue that is addressed by extensive ongoing basic and clinical research. AF centers around different types of disturbances, including ion channel dysfunction, Ca²⁺-handling abnormalities, and structural remodeling. Genome-wide association studies (GWAS) have uncovered over 100 genetic loci associated with AF. Most of these loci point to ion channels, distinct cardiac-enriched transcription factors, as well as to other regulatory genes. Recently, the discovery of post-transcriptional regulatory mechanisms, involving non-coding RNAs (especially microRNAs), DNA methylation, and histone modification, has allowed to decipher how a normal heart develops and which modifications are involved in reshaping the processes leading to arrhythmias. This review aims to provide a current state of the field regarding the identification and functional characterization of AF-related epigenetic regulatory networks

Long Non-Coding RNAs in Atrial Fibrillation: Pluripotent Stem Cell-Derived Cardiomyocytes as a Model System

Atrial fibrillation (AF) is a type of sustained arrhythmia in humans often characterized by devastating alterations to the cardiac conduction system as well as the structure of the atria. AF can lead to decreased cardiac function, heart failure, and other complications. Long non-coding RNAs (lncRNAs) have been shown to play important roles in the cardiovascular system, including AF; however, a large group of lncRNAs is not conserved between mouse and human. Furthermore, AF has complex networks showing variations in mechanisms in different species, making it challenging to utilize conventional animal models to investigate the functional roles and potential therapeutic benefits of lncRNAs for AF. Fortunately, pluripotent stem cell (PSC)-derived cardiomyocytes (CMs) offer a reliable platform to study lncRNA functions in AF because of certain electrophysiological and molecular similarities with native human CMs. In this review, we first summarize the broad aspects of lncRNAs in various heart disease settings, then focus on their potential roles in AF development and pathophysiology. We also discuss current uses of PSCs in AF research and describe how these studies could be developed into novel therapeutics for AF and other cardiovascular diseases.

Non-coding RNAs and Atrial Fibrillation

Atrial fibrillation is the most frequent type of cardiac arrhythmia in humans, with an estimate incidence of 1-2% in the general population, rising up to 8-10% in the elderly. Cardiovascular risk factors such as diabetes, obesity, hypertension and hyperthyroidism can increase the occurrence of AF. The onset of AF triggers additional AF episodes, leading to structural and electrical remodeling of the diseased heart. Understanding the molecular bases of atrial fibrillation have greatly advance over the last decade demonstrating a pivotal role of distinct ion channels in AF pathophysiology. A new scenario has opened on the understanding of the molecular mechanisms underlying AF, with the discovery of non-coding RNAs and their wide implication in multiple disease states, including cardiac arrhythmogenic pathologies. microRNAs are small non-coding RNAs of 22-24 nucleotides that are capable of regulating gene expression by interacting with the mRNA transcript 3'UTRs and promoting mRNA degradation and/or protein translation blockage. Long non-coding RNAs are a more diverse group of non-coding RNAs, providing transcriptional and post-transcriptional roles and subclassified according to their functional properties. In this chapter we summarized current state-of-the-art knowledge on the functional of microRNAs and long non-coding RNAs as well as their cross-talk regulatory mechanisms in atrial fibrillation.

Expedition to the missing link: Long noncoding RNAs in cardiovascular diseases

With the advances in deep sequencing-based transcriptome profiling technology, it is now known that human genome is transcribed more pervasively than previously thought. Up to 90% of the human DNA is transcribed, and a large proportion of the human genome is transcribed as long noncoding RNAs (lncRNAs), a heterogenous group of non-coding transcripts longer than 200 nucleotides. Emerging evidence suggests that lncRNAs are functional and contribute to the complex regulatory networks involved in cardiovascular development and diseases. In this article, we will review recent evidence on the roles of lncRNAs in the biological processes of cardiovascular development and disorders. The potential applications of lncRNAs as biomarkers and targets for therapeutics are also discussed.

Identification and characterization of circular RNAs in atrial appendage of patients with atrial fibrillation

Circular RNAs (circRNAs) have emerged as a novel type of non-coding RNA (ncRNA) of interest in gene regulation, especially for its vital function underlying many diseases. Atrial fibrillation is the most common sustained arrythmia. However, the expression spectrum and function of circRNAs in atrial appendage of patients with atrial fibrillation (AF) has seldomly been investigated. Human atrial appendage tissues were acquired during cardiac surgery, which were divided into the AF group and the Sinus rhythm (SR) group. The expression characterization of circRNAs of two groups was revealed by high-throughput sequencing. The dysregulated circRNAs were identified and analyzed by bioinformatics methods, and further validated by realtime PCR. A total 18109 circRNAs in human atrial appendage tissues were targeted. Among them, 147 differentially expressed circRNAs (102 up-regulated and 45 down-regulated) were found between AF group and SR group. Gene ontology (GO) and KEGG pathway analysis indicated that many mRNAs transcribed from the host genes of altered circRNAs were implicated in regulation of sequence-specific DNA binding transcription factor activity, as well as nicotinate and nicotinamide metabolism pathways. Analysis of the association between differently expressed circRNA and miRNA were explored, which revealed an ample interaction. Our study firstly revealed the expression spectrum of circRNAs in both left and right atrial appendage of patients with or without AF. Differentially expressed circRNAs in the atrial appendage were also identified, analyzed and validated. The results of this study may provide novel biomarkers and potential therapeutic targets for AF.

Interactions Among Regulatory Non-coding RNAs Involved in Cardiovascular Diseases

Non-coding RNAs (ncRNAs) are important regulatory players in human cells that have been shown to modulate different cellular processes and biological functions through controlling gene expression, being also involved in pathological conditions such as cardiovascular diseases. Among them, long non-coding RNAs (lncRNAs) and circular (circRNAs) could act as competing endogenous RNAs (ceRNAs) sequestering other ncRNAs. This entangled network of interactions has been reported to trigger the decay of the targeted ncRNAs having important roles in gene regulation. Growing evidences have been demonstrated that the regulatory mechanism underlying the crosstalk between different ncRNA species, namely lncRNAs, circRNAs and miRNAs has also an important role in the pathophysiological processes of cardiovascular diseases. In this chapter, the main regulatory relationship among lncRNAs, circRNAs and miRNAs were summarized and their role in the control and development of cardiovascular diseases was highlighted.

Non-coding RNAs and Cardiac Arrhythmias

Cardiac arrhythmias represent wide and heterogenic group of disturbances in the cardiac rhythm. Pathophysiology of individual arrhythmias is highly complex and dysfunction in ion channels/currents involved in generation or spreading of action potential is usually documented. Non-coding RNAs (ncRNAs) represent highly variable group of molecules regulating the heart expression program, including regulation of the expression of individual ion channels and intercellular connection proteins, e.g. connexins.Within this chapter, we will describe basic electrophysiological properties of the myocardium. We will focus on action potential generation and spreading in pacemaker and non-pacemaker cells, including description of individual ion channels (natrium, potassium and calcium) and their ncRNA-mediated regulation. Most of the studies have so far focused on microRNAs, thus, their regulatory function will be described into greater detail. Clinical consequences of altered ncRNA regulatory function will also be described together with potential future directions of the research in the field.

Comprehensive RNA-Seq Data Analysis Identifies Key mRNAs and lncRNAs in Atrial Fibrillation

Long non-coding RNAs (lncRNAs) are an emerging class of RNA species that may play a critical regulatory role in gene expression. However, the association between lncRNAs and atrial fibrillation (AF) is still not fully understood. In this study, we used RNA sequencing data to identify and quantify the both protein coding genes (PCGs) and lncRNAs. The high enrichment of these up-regulated genes in biological functions concerning response to virus and inflammatory response suggested that chronic viral infection may lead to activated inflammatory pathways, thereby alter the electrophysiology, structure, and autonomic remodeling of the atria. In contrast, the downregulated GO terms were related to the response to saccharides. To identify key lncRNAs involved in AF, we predicted lncRNAs regulating expression of the adjacent PCGs, and characterized biological function of the dysregulated lncRNAs. We found that two lncRNAs, ETF1P2, and AP001053.11, could interact with protein-coding genes (PCGs), which were implicated in AF. In conclusion, we identified key PCGs and lncRNAs, which may be implicated in AF, which not only improves our understanding of the roles of lncRNAs in AF, but also provides potentially functional lncRNAs for AF researchers.

Long Noncoding RNAs in Pathological Cardiac Remodeling: A Review of the Update Literature

Cardiac remodeling is a self-regulatory response of the myocardium and vasculature under the stressful condition. Cardiomyocytes (CMs), vascular smooth muscle cells (VSMCs), endothelial cells (ECs), and cardiac fibroblasts (CFs) are all involved in this process, characterized by change of morphological structures and mechanical/chemical activities as well as metabolic patterns. Despite current development of consciousness, the control of cardiac remodeling remains unsatisfactory, and to further explore the underlying mechanism and seek the optimal therapeutic targets is still the urgent need in clinical practice. It is now emerging that long noncoding RNAs (lncRNAs) play key regulatory roles in these adverse responses: lncRNA TUG1, AK098656, TRPV1, GAS5, Giver, and Lnc-Ang362 have been indicated in hypertension-related vascular remodeling, H19, TUG1, UCA1, MEG3, APPAT, and lincRNA-p21 in atherosclerosis (AS), and HIF1A-AS1 and Lnc-HLTF-5 in aortic aneurysm (AA). In addition, Neat1, AK139328, APF, CAIF, AK088388, CARL, MALAT1, HOTAIR, XIST, and NRF are involved in postischemia myocardial remodeling, while Mhrt, Chast, CHRF, ROR, H19, Plscr4, and MIAT are involved in myocardial hypertrophy, and MALAT1, wisper, MEG3, and H19 are involved in extracellular matrix (ECM) reconstitution. Signaling to specific miRNAs by acting as endogenous sponge (ceRNA) was the main form that regulates the target gene expression during cardiac remodeling. This review will underline the updates of lncRNAs and lncRNA-miRNA interactions in maladaptive remodeling and also cast light on their potential roles as therapeutic targets, hoping to provide supportive background for following research.

circRNA-miRNA cross-talk in the transition from paroxysmal to permanent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in western countries. The factors governing the progression of AF to a permanent chronic condition are still not well characterized. Among epigenetic factors, non-coding RNAs (ncRNAs) such as miRNAs and lncRNAs have been recently described as important players involved in the AF progression. We hypothesize about the existence of additional regulatory layers in AF involving an intricate cross-talk between different ncRNA species, namely miRNAs and circRNAs for the establishment of a chronic AF condition.

METHODS AND RESULTS

We have performed an unbiased study analyzing the expression profile for miRNAs and circRNAs in left-atrial biopsies from patients with paroxysmal and permanent AF by RNA-seq. The transition from paroxysmal to permanent AF is characterized by a pattern of down-regulated miRNAs, concomitant to the appearance of specific circRNA species. The analysis of the sponging activities of the circRNAs exclusively expressed in permanent AF samples, allowed us to determine that they could be responsible for the downregulation of specific miRNAs in establishment of a permanent AF condition.

CONCLUSION

Sponging activity of circRNAs sequestering specific miRNAs is an important factor to be considered for the determination of the molecular mechanisms involved in AF progression.

The expression profile analysis of atrial mRNA in rats with atrial fibrillation: the role of IGF1 in atrial fibrosis

Background

Structural remodeling is critical to the initiation and maintenance of atrial fibrillation (AF). IGF1, insulin like growth factor 1, has been recognized as contributor to fibrosis. However, the roles and mechanisms of IGF1 in structural remodeling during AF is still unclear.

Methods

We investigated the transcriptional expression profiles of left atria in AF and non-AF rat models by using microarray analysis. And quantitative real-time polymerase chain reaction (qRT-PCR) was performed to validate the accuracy. After bioinformatics analysis, IGF1 was selected to explore its effects and mechanisms on atrial fibrosis. The fibroblasts were extracted from atria of rats, and randomly divided into negative control group, mIGF1 overexpression group and mIGF1 silencing group. Then 30 healthy male Wistar rats were randomly divided into negative control group (n = 10), pacing group (n = 10), pacing + mIGF1 silencing viruses group (n = 10). Then the intracardiac electrophysiological examination, qRT-PCR, Western Blotting, masson staining were conducted after IGF1 interfering experiments.

Results

A total of 956 differentially expressed transcripts were identified, in which 395 transcripts were down-regulated and 561 transcripts were up-regulated. Bioinformatics analysis was conducted to predict the functions and interactions of the aberrantly expressed genes. The inhibition of IGF1 function in AF model could ameliorate the inducibility of AF. The IGF1 plays a fibrotic role by activating the PI3K-Akt pathway to increase the expression of CTGF and AT1R.

Conclusions

IGF1 develops vital function in regulating structural remodeling during AF, which could illustrate the mechanism of AF pathogenesis and supply potential targets for its precise treatment.

Long Non-coding RNA Expression Profile and Functional Analysis in Children With Acute Fulminant Myocarditis

Long non-coding RNA (lncRNA) has been associated with human diseases. To study the role of lncRNA in the pathogenic mechanism of acute fulminant myocarditis (AFM), we used a microarray to analyze lncRNA and messenger RNA (mRNA) expression in leukocyte samples from AFM patients and normal children. In total, using a 2/0.5-fold change and P < 0.05 as the cutoff criteria, we found that 3,101 lncRNAs and 2,170 mRNAs were differentially expressed in AFM patients. Quantitative real-time polymerase chain reaction (RT-qPCR) analysis was used to verify the microarray data. Eight differentially expressed molecules were randomly selected, including 3 upregulated lncRNAs, 3 downregulated lncRNAs, and 2 upregulated mRNAs. Among them, 7 expression profiles were consistent with the microarray results. Gene Ontology enrichment and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis were used to investigate the biological functions of these genes. Establishment of a lncRNA-mRNA co-expression network and lncRNA target predication were performed to study the molecular interactions of these molecules. Our study is the first to use microarrays to examine the lncRNA and mRNA expression profiles associated with AFM, and the results indicate that the immune system plays an important role in AFM. These findings may provide a new perspective for the pathogenesis, diagnosis, and therapy of AFM.

Genetics of Atrial Fibrilation: In Search of Novel Therapeutic Targets

Atrial fibrillation (AF) is the most frequent arrhythmogenic disease in humans, ranging from 2% in the general population and rising up to 10-12% in 80+ years. Genetic analyses of AF familiar cases have identified a series of point mutations in distinct ion channels, supporting a causative link. However, these genetic defects only explain a minority of AF patients. Genomewide association studies identified single nucleotide polymorphisms (SNPs), close to PITX2 on 4q25 chromosome, that are highly associated to AF. Subsequent GWAS studies have identified several new loci, involving additional transcription and growth factors. Furthermore, these risk 4q25 SNPs serve as surrogate biomarkers to identify AF recurrence in distinct surgical and pharmacological interventions. Experimental studies have demonstrated an intricate signalling pathway supporting a key role of the homeobox transcription factor PITX2 as a transcriptional regulator. Furthermore, cardiovascular risk factors such as hyperthyroidism, hypertension and redox homeostasis have been identified to modulate PITX2 driven gene regulatory networks. We provide herein a state-of-the-art review of the genetic bases of atrial fibrillation, our current understanding of the genetic regulatory networks involved in AF and its plausible usage for searching novel therapeutic targets.

The novel regulatory role of lncRNA-miRNA-mRNA axis in cardiovascular diseases

Long noncoding RNAs (lncRNAs) are RNAs longer than 200 nt in length that are characterized by low levels of sequence conservation and expression; lncRNAs modulate various biological functions at epigenetic, transcriptional and post-transcriptional levels, or directly regulate protein activity. As a family of small and evolutionarily conserved noncoding RNAs, microRNAs (miRNAs) are capable of regulating physiological and pathological processes via inhibiting target mRNA translation or promoting mRNA degradation. A number of studies have confirmed that both lncRNAs and miRNAs are closely associated with the development of cardiovascular diseases (CVDs), such as cardiac remodelling, heart failure, myocardial injury and arrhythmia, and that they act as biomarkers, potential therapeutic targets or strong indicators of prognosis; however, the underlying molecular mechanism has not been elucidated. Recently, emerging evidence showed that the novel regulatory mechanism underlying the crosstalk among lncRNAs, miRNAs and mRNAs plays a pivotal role in the pathophysiological processes of CVDs in response to stress stimuli. In this review, I comprehensively summarized the regulatory relationship of lncRNAs, miRNAs and mRNAs and highlighted the important role of the lncRNA-miRNA-mRNA axis in CVDs.

Identification of functional lncRNAs in atrial fibrillation by integrative analysis of the lncRNA-mRNA network based on competing endogenous RNAs hypothesis

A mounting body of evidence has suggested that long noncoding RNAs (lncRNAs) play critical roles in human diseases by acting as competing endogenous RNAs (ceRNAs). However, the functions and ceRNA mechanisms of lncRNAs in atrial fibrillation (AF) remain to date unclear. In this study, we constructed an AF-related lncRNA-mRNA network (AFLMN) based on ceRNA theory, by integrating probe reannotation pipeline and microRNA (miRNA)-target regulatory interactions. Two lncRNAs with central topological properties in the AFLMN were first obtained. By using bidirectional hierarchical clustering, we identified two modules containing four lncRNAs, which were significantly enriched in many known pathways of AF. To elucidate the ceRNA interactions in certain disease or normal condition, the dysregulated lncRNA-mRNA crosstalks in AF were further analyzed, and six hub lncRNAs were obtained from the network. Furthermore, random walk analysis of the AFLMN suggested that lncRNA RP11-296O14.3 may function importantly in the pathological process of AF. All these eight lncRNAs that were identified from previous steps (RP11-363E7.4, GAS5, RP11-410L14.2, HAGLR, RP11-421L21.3, RP11-111K18.2, HOTAIRM1, and RP11-296O14.3) exhibited a strong diagnostic power for AF. The results of our study provide new insights into the functional roles and regulatory mechanisms of lncRNAs in AF, and facilitate the discovery of novel diagnostic biomarkers or therapeutic targets.