Chuang Cheng-Yen, Wang Bao-Wei, Yu Ying-Ju, Fang Wei-Jen, Lin Chiu-Mei, Shyu Kou-Gi, Chua Su-Kiat
Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 11101, Taiwan.
Department of Emergency Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 11101, Taiwan.
Cells. 2024 Nov 22;13(23):1942. doi: 10.3390/cells13231942.
Atrial fibrillation (AF) is a common cardiac arrhythmia associated with significant morbidity and mortality. Rapid electrical stimulation (RES) of atrial fibroblasts plays a crucial role in AF pathogenesis, but the underlying molecular mechanisms remain unclear. This study investigates the regulatory axis involving MALAT1, miR-499a-5p, and SOX6 in human cardiac fibroblasts from adult atria (HCF-aa) under RES conditions.
HCF-aa were subjected to RES at 0.5 V/cm and 10 Hz. The expression levels of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), miR-499a-5p, and SRY-Box Transcription Factor 6 (SOX6) were measured using qPCR and Western blot analyses. Luciferase reporter assays were performed to confirm target relationships. The effects of MALAT1 siRNA, miR-499a-5p mimics/inhibitors, and SOX6 overexpression on gene expression and apoptosis were assessed.
RES increased exosomal MALAT1 expression, peaking at 2 h. MiR-499a-5p levels initially increased, then decreased at 2 h, coinciding with peak MALAT1 expression. SOX6 mRNA and protein levels increased, peaking at 4 and 6 h, respectively. Luciferase assays confirmed MALAT1 and SOX6 as miR-499a-5p targets. MALAT1 knockdown increased miR-499a-5p levels and reduced SOX6 expression. MiR-499a-5p overexpression decreased SOX6 levels and inhibited RES-induced apoptosis.
In HCF-aa under RES, increased exosomal MALAT1 expression counteracts miR-499-5p's suppression of SOX6, suggesting that MALAT1-containing exsosomes derived from HCF-aa may offer a novel cell-free therapeutic approach for AF.
心房颤动（AF）是一种常见的心律失常，与显著的发病率和死亡率相关。心房成纤维细胞的快速电刺激（RES）在AF发病机制中起关键作用，但其潜在的分子机制仍不清楚。本研究调查了RES条件下成人心房来源的人心脏成纤维细胞（HCF-aa）中涉及MALAT1、miR-499a-5p和SOX6的调控轴。
将HCF-aa置于0.5 V/cm和10 Hz的RES条件下。使用qPCR和蛋白质印迹分析测量转移相关肺腺癌转录本1（MALAT1）、miR-499a-5p和SRY盒转录因子6（SOX6）的表达水平。进行荧光素酶报告基因测定以确认靶标关系。评估MALAT1 siRNA、miR-499a-5p模拟物/抑制剂和SOX6过表达对基因表达和细胞凋亡的影响。
RES增加了外泌体MALAT1的表达，在2小时达到峰值。miR-499a-5p水平最初升高，然后在2小时下降，与MALAT1表达峰值一致。SOX6 mRNA和蛋白质水平升高，分别在4小时和6小时达到峰值。荧光素酶测定证实MALAT1和SOX6是miR-499a-5p的靶标。MALAT1敲低增加了miR-499a-5p水平并降低了SOX6表达。miR-499a-5p过表达降低了SOX6水平并抑制了RES诱导的细胞凋亡。
在RES条件下的HCF-aa中,外泌体MALAT1表达增加抵消了miR-499-5p对SOX6的抑制作用，这表明源自HCF-aa的含MALAT1外泌体可能为AF提供一种新的无细胞治疗方法。
