In recent years, although cardiologists have made great progress for the diagnosis and treatment of AF, the high incidence and high disability rate induced by AF still constitute a heavy medical burden globally. And some points regarding the pathogenesis of AF are still unclear. In this study, we constructed a regulatory network of 7 circRNAs, 42 miRNAs, and 25 mRNAs using GEO datasets to explore the potential circRNA involved in AF. Combining the results of enrichment analysis, we determined the occurrence mechanism in calcium signaling-related pathway, second messenger-mediated signaling-related pathway, programmed cell death pathway, and renin–angiotensin pathway (Supplementary Table S20).
There are four hub genes, namely, ADRA2A, P2RY12, CXCL11, and PTGS2, involved in the regulation of calcium ion transport pathway and second messenger-mediated signaling pathway. The hsa_circ_0001666/hsa_miR-1827/ADRA2A pathway involved in AF through the second messenger signaling pathway. Previous study also showed that lacking ADRA2A elevated plasma noradrenaline concentrations and participated in the development of cardiac hypertrophy and dysfunction[11]. In addition, hsa_circ_0000288, hsa_circ_0021652/hsa_miR-548m/P2RY12 network also played an important role in AF through a similar mechanism. The latest research illustrated that the crosstalk between P2Y12 and IGF-I receptors can increase PKB phosphorylation through calcium-dependent activation of the Pyk2/Src pathway[12]. The hub gene PTGS2 involved in more complex circRNA/miRNA/mRNA regulatory networks in AF including 5 circRNA, such as hsa_circ_0001666, hsa_circ_0006168, hsa_circ_0021652, hsa_circ_0000288, and hsa_circ_0030162. Previous research also demonstrated that the combination of PTGS2 and miRNA-26 can inhibit the MAPK pathway and reduce the inflammatory response and myocardial remodeling of mice with myocardial infarction[13].
Moreover, there are three hub genes, namely, IL1B, KIT, and KITLG, involved in the programmed cell death pathway. Our research data revealed that the hsa_circ_0001666/hsa_miR-590-5p/IL1B involved in AF via programmed cell death pathway. And hsa_circ_0021652, hsa_circ_0000288/hsa_miR-583/KIT networks also participated in AF via similar pathway. Previous research results suggested that IL1B genetic variation is involved in mediating CRP expression [14]. In reviewing the literature, no data was found about the association between CXCL11, KIT, and KITLG in cardiac diseases. The hsa_circ_0001666/miR-1827/ADRA2A pathway, the hsa_circ_0000288 or hsa_circ_0021652/miR-548m/P2RY12 pathway, circ_0001666/miR-590-5p/IL1B pathway, will become the target regulation network of our research.
Furthermore, a total of four miRNAs, namely, miR-1263, miR-1299, miR-1322, and miR-330-3p, were involved in the renin–angiotensin system and second messenger-mediated signaling pathway with the AGTR2 gene. Previous studies revealed that AGTR2 is involved in regulating collagen accumulation and MMP expression[15]. The network showed that hsa_circ_0001666 can adsorb three miRNAs, namely, miR-1299, miR-1322, and miR-330-3p, while hsa_circ_0000367 interacts with miR-1263. The other three circRNAs, hsa_circ_0030162, hsa_circ_0021652, and hsa_circ_0000288, can also interact with miR-1322 to influence AGTR2 expression in AF. The regulatory network involved in AGTR2 can become the most valuable target in our future research work.
The main limitation of this study is the small sample size, which may have resulted in selection bias. Therefore, further genomics research on more specimen sources is required to validate these results. We are currently preparing to perform knockdown and overexpression experiments to explore the effects of changes in the expression of circRNAs and associated key genes using cell and animal models. Despite these limitations, the findings of this study suggest that circRNAs are also potential biomarkers or therapeutic targets for AF, offering a guide for further research to better understand the mechanism of AF.