Abstract

MicroRNAs (miRs) contribute to different aspects of cardiovascular pathology, among others cardiac hypertrophy and atrial fibrillation. The aim of our study was to evaluate the impact of miR-221/222 on cardiac electrical remodeling. Cardiac miR expression was analyzed in a mouse model with altered electrocardiography parameters and severe heart hypertrophy. Next generation sequencing revealed 14 differentially expressed miRs in hypertrophic hearts, with miR-221 and -222 being the strongest regulated miR-cluster. This increase was restricted to cardiomyocytes and not observed in cardiac fibroblasts. Additionally, we evaluated the change of miR-221/222 in vivo in two models of pharmacologically induced heart hypertrophy (angiotensin II, isoprenaline), thereby demonstrating a stimulus-induced increase in miR-221/222 in vivo by angiotensin II but not by isoprenaline. Whole transcriptome analysis by RNA-seq and qRT-PCR validation revealed an enriched number of downregulated mRNAs coding for proteins located in the T-tubule, which are also predicted targets for miR-221/222. Among those, mRNAs were the L-type Ca²⁺ channel subunits as well as potassium channel subunits. We confirmed that both miRs target the 3′-untranslated regions of Cacna1c and Kcnj5. Furthermore, enhanced expression of these miRs reduced L-type Ca²⁺ channel and Kcnj5 channel abundance and function, which was analyzed by whole-cell patch clamp recordings or Western blot and flux measurements, respectively. miR-221 and -222 contribute to the regulation of L-type Ca²⁺ channels as well as Kcnj5 channels and, therefore, potentially contribute to disturbed cardiac excitation generation and propagation. Future studies will have to evaluate the pathophysiological and clinical relevance of aberrant miR-221/222 expression for electrical remodeling.

中文翻译：

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miR-221和-222靶向CACNA1C和KCNJ5，导致心脏离子通道表达和电流密度改变

 抽象的

MicroRNA (miR) 与心血管病理学的不同方面有关，其中包括心脏肥大和心房颤动。我们研究的目的是评估 miR-221/222 对心脏电重构的影响。在心电图参数改变和严重心脏肥大的小鼠模型中分析了心脏 miR 表达。下一代测序揭示了肥大心脏中 14 个差异表达的 miR，其中 miR-221 和 -222 是最强调控的 miR 簇。这种增加仅限于心肌细胞，在心脏成纤维细胞中未观察到。此外，我们在两种药物诱导的心脏肥大模型（血管紧张素II、异丙肾上腺素）中评估了体内miR-221/222的变化，从而证明了血管紧张素II刺激诱导的体内miR-221/222增加，而血管紧张素II则不然。异丙肾上腺素。通过 RNA-seq 和 qRT-PCR 验证进行的全转录组分析显示，编码 T 管中蛋白质的下调 mRNA 数量丰富，这些蛋白质也是 miR-221/222 的预测靶点。其中，mRNA是L型Ca ²⁺通道亚基以及钾通道亚基。我们证实这两个 miR 都靶向 Cacna1c 和 Kcnj5 的 3'-非翻译区。此外，这些 miR 表达的增强降低了 L 型 Ca ²⁺通道和 Kcnj5 通道的丰度和功能，这分别通过全细胞膜片钳记录或蛋白质印迹和通量测量进行了分析。 miR-221 和-222 有助于L 型Ca ²⁺通道以及Kcnj5 通道的调节，因此可能有助于扰乱心脏兴奋的产生和传播。 未来的研究将必须评估异常 miR-221/222 表达与电重塑的病理生理学和临床相关性。