Atrial fibrillation (AF) is the most common sustained arrhythmia characterized by irregular high-frequency excitation and contraction of the atria, and is a major contributor to stroke, heart failure and sudden death (1–3). Approximately 1–2% of the common population suffer from AF, with the prevalence up to over 10% for individuals aged ≥80 years (1, 2, 4, 5). However, there is a lack of effective therapy for AF in general, largely because the pathophysiologic mechanism underlying AF remains unclear. The underlying pathogenesis of AF is multiplex, including electrical remodeling, structural remodeling, Ca²⁺ handling abnormalities and autonomic nervous system changes (6).

Previous studies have identified that non-coding RNAs (ncRNAs) play a critical role in the pathogenesis of AF by regulating core proteins and pivotal pathways (7). Long non-coding RNAs (lncRNAs) are a class of endogenous ncRNAs whose length are >200 nucleotides with no protein-coding potential (8). A number of studies have demonstrated that lncRNAs are involved in multiple biological processes by regulating genes of transcriptional, posttranscriptional, and epigenetic levels (9). Dysregulations of lncRNA expressions and functions have been implicated in the development and progression of many diseases including cancer, neurodegeneration diseases and cardiovascular diseases (10–12).

Competing endogenous RNA (ceRNA) is a novel regulation mechanism in which lncRNA can competitively combine with miRNAs through microRNA response elements (MREs), thus inhibiting gene silencing by isolating miRNAs from messenger RNAs (mRNAs) (13–15). This regulation mechanism has been observed in some cardiovascular diseases. For example, lncRNA PEL was shown to function as a ceRNA to competitively band let-7d and contribute to cardiac fibrosis (16). In addition, lncRNA TNK2-AS1 could regulate ox-LDL-stimulated human aortic smooth muscle cell proliferation and migration by serving as a ceRNA for miR-150-50 to modulate VEGFA and FGF1 expression (17). However, the ceRNA mechanisms related to AF remained largely unclear and required further investigation.

Therefore, in the present study, we aimed to construct the lncRNA-miRNA-mRNA network based on ceRNA theory in AF by using bioinformatic analyses of public datasets. Findings from the ceRNA network may help improve our understanding of lncRNA-mediated ceRNA regulatory mechanisms in the pathogenesis of AF.

In this bioinformatics study, we integrated gene expression profiles of 46 AF samples and 31 SR samples from 2 GEO datasets. We identified 8 lncRNAs and 43 mRNA were significantly differentially expressed with fold change >1.5 (p < 0.05). Furthermore, the LOC101928304/miR-490-3p/LRRC2 network based on ceRNA theory was constructed in AF. The expression of LOC101928304 and LRRC2 were up-regulated in myocardial tissue of patients with AF, while miR-490-3p was down-regulated.

Recently, the pathological functions of lncRNAs and miRNAs in cardiovascular disease have been recognized, making them potential candidates as therapeutic targets and biomarkers. However, AF-related lncRNAs and miRNAs still required further research. Recent studies have investigated the expression profiles of lncRNA in AF patients (20–25). For instance, Xu et al. detected the expression levels of lncRNAs in AF in elderly patients, which showed that lncRNAs were closely involved in the pathogenesis of AF (26). Moreover, an increasing number of reports indicate that lncRNAs can regulate protein-coding genes in mammals through the ceRNA network (27), where lncRNAs function as miRNA sponges to upregulate the expression of their targets (28). For instance, Liu et al. identified LINC00964 as a key lncRNA in AF susceptibility- and persistence-associated ceRNA networks (29). By integrating three microarray datasets and construction of a ceRNA network, the study by Wu et al. discovered that HCG11, KRBOX1-AS1, ACBD5 and RAD52 may compete with WEE1 for has-miR-17-5p to affect the development of AF (30). However, given the sparse existing evidence in the literature, the ceRNA mechanisms related to AF remained largely obscure and required further investigation.

Previous studies have found an association between LOC101928304 and cardiovascular diseases. Qiu et al. found that LOC101928304 were related with the functions of blood circulation and heart contraction using high-throughput sequencing of lncRNAs in myocardial tissues collected from patients with dilated cardiomyopathy (DCM) and normal heart donors (31). They also confirmed that LOC101928304 were downregulated in DCM tissues by using real-time PCR (31). Likewise, one study reported that miR-490-3p played a key role in different acute and chronic cardiovascular disease processes (32). Downregulation of miR-490-3p expression in atherosclerosis patients, and miR-490-3p which enhanced cell proliferation and migration of vascular smooth muscle cells and human umbilical vein endothelial cells in atherosclerosis (33, 34). The inhibition of miR-490-3p could promote autophagy to reduce myocardial ischemia reperfusion (IR) injury by upregulating ATG4B (35). Qiang et al. investigated that miR-490-3p was downregulated in patients with chronic heart failure (HF), which might provide novel targets for prevention and treatment of chronic HF (36). Cao et al. revealed that miR-490-3p was down-regulated in AF, which had a potential diagnostic value to distinguish patients with AF from healthy controls (37). First, we constructed the ceRNA network based on lncRNA and mRNA, and predicted the corresponding miRNA. In subsequent verification, we carried out an exploratory analysis because the sample size was limited. Under these circumstances, even if its adjusted P > 0.05, we still have reason to believe that miR-490-3p has potential to be part of the ceRNA network that could be combined with published literature, which should be further verified in subsequent experimental studies. Taken together, our findings were consistent with results from previous studies in that miR-490-3p may participate in the ceRNA network of LOC101928304.

LRRC2 located in chromosome three common eliminated region one, is a member of the leucine-rich repeat-containing family of proteins that have been implicated in various biological pathways. Recently, LRRC2 has been reported to correlate with transcripts associated with cardiac remodeling, thereby playing critical roles in the processes of cardiomyocyte hypertrophy and mitochondrial abundance (38). RNAi-mediated LRRC2 knockdown in a rat-derived cardiomyocyte cell line resulted in enhanced expression of canonical hypertrophic biomarkers as well as increased mitochondrial mass in the context of increased PGC-1α expression (38). LRRC2 partially localized to the mitochondrion and regulated by the mitochondrial master regulator PGC-1α (38). Most notably, mitochondrial dysfunction and cardiomyocyte hypertrophy increase the heterogeneity of atrial electrical conduction, leading to change in atrial structure and potentially facilitating the development of AF (39). The expression of PGC-1α was significantly decreased in AF model of rabbits with rapid pacing, indicating that mitochondrial biosynthesis was impaired in AF (40). LRRC2 may be a mediator of mitochondrial and cardiac function, which involve the PGC-1α-dependent mitochondrial abundance regulation mechanism, thereby ultimately facilitating the development of AF. Nevertheless, a more thorough understanding of LOC101928304/miR-490-3p/LRRC2 pathway in AF is necessary.

Discovering ncRNA-disease associations may help generate diagnostic and therapeutic tools for diseases. However, since uncovering associations via experimental studies are resource and time consuming, bioinformatic analyses for the identification of ncRNAs associated with AF are a helpful approach for preliminary exploration. In our study, we constructed a novel lncRNA-miRNA-mRNA network (LOC101928304/miR-490-3p/LRRC2) based on the ceRNA theory, which may therefore provide insights into the ceRNA regulatory mechanisms in the pathogenesis of AF. However, our study has some limitations. First, it is difficult to integrate some important factors for analyses, including regions, races and age. Given that the development of AF was caused by numerous environmental and genetic factors, our findings may be influenced by some immeasurable risk factors to an unknown extent. Additionally, specimens were obtained only from within the RAA, whereas AF is predominantly a left atrial disease. KEGG pathway analyses showed that the differently expression lncRNAs were mainly associated with cardiac muscle contraction. The up-regulated ATP1B4 and down-regulated TRDN were enriched in cardiac muscle contraction. Therefore, LOC101928304/miR-490-3p/LRRC2 may be involved in AF through other pathways. Our study may provide some new insights into the AF mechanism based on the bioinformatics analyses; however, the significantly differentially expressed lncRNAs and mRNAs would require experimental investigation of RT-PCR in clinical samples for further validation. In addition, the significantly differentially expressed lncRNAs require experimental investigations using the left atria appendage/pulmonary vein region samples for further validation. Likewise, future experimental research is needed to validate the ceRNA network of LOC101928304/miR-490-3p/LRRC2 in the pathogenesis of AF.

The LOC101928304/miR-490-3p/LRRC2 network based on ceRNA theory was constructed in AF in this bioinformatic analysis study. The novel ceRNA network found from this study may help improve our understanding of lncRNA-mediated ceRNA regulatory mechanisms in the pathogenesis of AF.

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/Supplementary Material.

XK, JZ, ZY, and GL were responsible for study conception, design of the study, data acquisition, and analysis and interpretation of results. ML was responsible for data acquisition. ML, XH, and SL took part in the discussion of the paper. XK wrote the manuscript that was reviewed and revised by GL, ZY, ML, XH, and SL. All authors gave approval of the version to be submitted.

This work was supported by the Medical Scientific Research Foundation of Guangdong Province of China (Grant sponsor: GL; Grant no. A2020453), the Science Foundation of Guangdong Second Provincial General Hospital (Grant sponsor: GL; Grant no.YY2018-002), and Doctoral workstation foundation of Guangdong Second Provincial general Hospital (Grant sponsor: XK; Grant no. 2021BSGZ008).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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