Alcohol exposure impairs myocardium insulin sensitivity, which links to heart dysfunction. miR-155 regulates mTOR signaling pathway and is involved in multiple functions. However, the underlying mechanism of miR-155 in ethanol-induced myocardial insulin resistance remains unclear. Here, in this study we aimed to identify the role of miR-155 in myocardial insulin sensitivity and the involvement of mTOR pathway. H9C2 cells were cultured with or without 100 mM ethanol for 24 h. miR-155-5p inhibitor, miR-155-5p mimics or their respective negative control (inhibitor NC and mimic NC) were transfected to regulate miR-155-5p expression. mTOR signaling, including Ras homolog enriched in brain (Rheb), rapamycin insensitive companion of mTOR (Rictor) and ribosomal protein S6 kinase B2 (S6K2), was investigated by western blotting and qPCR, and insulin responsiveness was evaluated by glucose uptake and phosphorylation of insulin receptor substrate-1 (p-IRS1). The miR-155-5p level increased under ethanol exposure, accompanied by a decrease in glucose uptake, an increase in p-IRS1(ser 307) and activation of the mTOR signaling pathway in H9C2 cells. In addition, miR-155-5p downregulation decreased the glucose uptake, increased the p-IRS1(ser 307) level and activated the mTOR signaling pathway. miR-155-5p upregulation increased the glucose uptake, decreased the p-IRS1(ser 307) level and suppressed the mTOR signaling pathway. Collectively, these findings suggest miR-155-5p upregulation ameliorates myocardial insulin resistance via mTOR signaling in vitro, and miR-155-5p downregulation attenuates myocardial insulin resistance, which might become a potential therapeutic target for alcohol-induced cardiomyopathy.

饮酒会损害心肌胰岛素敏感性，这与心脏功能障碍有关。miR-155调节mTOR信号传导途径，并参与多种功能。然而，miR-155在乙醇诱导的心肌胰岛素抵抗中的潜在机制仍不清楚。在此，本研究旨在确定miR-155在心肌胰岛素敏感性中的作用以及mTOR途径的参与。H9C2细胞在有或没有100 mM乙醇的情况下培养24小时。将miR-155-5p抑制剂，miR-155-5p模拟物或它们各自的阴性对照（抑制剂NC和模拟NC）转染以调节miR-155-5p表达。通过Western印迹和qPCR研究了mTOR信号，包括富含脑的Ras同源物（Rheb），雷帕霉素不敏感的mTOR伴侣（Rictor）和核糖体蛋白S6激酶B2（S6K2），并通过胰岛素受体底物1（p-IRS1）的葡萄糖摄取和磷酸化来评估胰岛素反应性。在乙醇暴露下，miR-155-5p水平升高，同时葡萄糖摄取减少，p-IRS1（ser 307）增加和H9C2细胞中mTOR信号通路的激活。此外，miR-155-5p的下调降低了葡萄糖的摄取，增加了p-IRS1（ser 307）的水平并激活了mTOR信号通路。miR-155-5p上调增加了葡萄糖的摄取，降低了p-IRS1（ser 307）的水平，并抑制了mTOR信号通路。总的来说，这些发现表明miR-155-5p的上调通过mTOR信号在体外改善了心肌胰岛素抵抗，而miR-155-5p的下调则减弱了心肌胰岛素抵抗，