To explore the underlying molecular mechanisms of supraventricular tachycardia (SVT), this study aimed to analyse the complex relationship between FLRT3 and TGF‐β/SMAD4 signalling pathway, which affects Na+ and K+ channels in cardiomyocytes. Bioinformatics analysis was performed on 85 SVT samples and 15 healthy controls to screen overlapping genes from the key module and differentially expressed genes (DEGs). Expression profiling of overlapping genes, coupled with Receiver Operating Characteristic (ROC) curve analyses, identified FLRT3 as a hub gene. In vitro studies utilizing Ang II‐stimulated H9C2 cardiomyocytes were undertaken to elucidate the consequences of FLRT3 silencing on cardiomyocyte apoptosis and autophagic processes. Utilizing a combination of techniques such as quantitative reverse‐transcription polymerase chain reaction (qRT‐PCR), western blotting (WB), flow cytometry, dual‐luciferase reporter assays and chromatin immunoprecipitation polymerase chain reaction (ChIP‐PCR) assays were conducted to decipher the intricate interactions between FLRT3, the TGF‐β/SMAD4 signalling cascade and ion channel gene expression. Six genes (AADAC, DSC3, FLRT3, SYT4, PRR9 and SERTM1) demonstrated reduced expression in SVT samples, each possessing significant clinical diagnostic potential. In H9C2 cardiomyocytes, FLRT3 silencing mitigated Ang II‐induced apoptosis and modulated autophagy. With increasing TGF‐β concentration, there was a dose‐responsive decline in FLRT3 and SCN5A expression, while both KCNIP2 and KCND2 expressions were augmented. Moreover, a direct interaction between FLRT3 and SMAD4 was observed, and inhibition of SMAD4 expression resulted in increased FLRT3 expression. Our results demonstrated that the TGF‐β/SMAD4 signalling pathway plays a critical role by regulating FLRT3 expression, with potential implications for ion channel function in SVT.

中文翻译：

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FLRT3 和 TGF-β/SMAD4 信号传导：对室上性心动过速细胞凋亡、自噬和离子通道的影响

为了探讨室上性心动过速（SVT）的潜在分子机制，本研究旨在分析FLRT3与TGF-β/SMAD4信号通路之间的复杂关系，从而影响Na+和K+心肌细胞中的通道。对 85 个 SVT 样本和 15 个健康对照进行生物信息学分析，筛选关键模块中的重叠基因和差异表达基因 (DEG)。重叠基因的表达谱与受试者工作特征 (ROC) 曲线分析相结合，将 FLRT3 确定为中心基因。利用 Ang II 刺激的 H9C2 心肌细胞进行体外研究，以阐明 FLRT3 沉默对心肌细胞凋亡和自噬过程的影响。结合使用定量逆转录聚合酶链反应 (qRT-PCR)、蛋白质印迹 (WB)、流式细胞术、双荧光素酶报告基因检测和染色质免疫沉淀聚合酶链反应 (ChIP-PCR) 检测等技术来破译FLRT3、TGF-β/SMAD4 信号级联和离子通道基因表达之间复杂的相互作用。六个基因（AADAC、DSC3、FLRT3、SYT4、PRR9 和 SERTM1）在 SVT 样本中表现出表达降低，每个基因都具有显着的临床诊断潜力。在 H9C2 心肌细胞中，FLRT3 沉默可减轻 Ang II 诱导的细胞凋亡并调节自噬。随着TGF-β浓度的增加，FLRT3和SCN5A的表达出现剂量反应性下降，而KCNIP2和KCND2的表达则增加。此外，观察到 FLRT3 和 SMAD4 之间的直接相互作用，抑制 SMAD4 表达会导致 FLRT3 表达增加。我们的结果表明，TGF-β/SMAD4 信号通路通过调节 FLRT3 表达发挥着关键作用，对 SVT 中的离子通道功能具有潜在影响。