Wang Jinyang, Gao Yanbin, Duan Lijun, Wei Suhong, Liu Jing, Tian Liming, Quan Jinxing, Zhang Qi, Liu Juxiang, Yang Jinkui
Department of Endocrinology, Gansu Provincial People's hospital, Lanzhou, China.
Gansu Provincial Key Laboratory of Endocrine and metabolism, Lanzhou, China.
Oncotarget. 2017 Aug 24;8(58):98029-98039. doi: 10.18632/oncotarget.20442. eCollection 2017 Nov 17.
Insulin resistance (IR) plays a major role in the pathogenesis of abdominal obesity, hypertension, coronary heart disease, atherosclerosis and diabetes. miR-21 and TGF-β/smads is closely related to IR. However, it remained elusive whether metformin improved skeletal muscle insulin resistance (IRSM) by regulating miR-21 and its target signal TGF-β1/smads expression. In this study, high-fat diet rats with IR model and IR-skeletal muscle L6 cells (L6-SMCs) model were established, insulin sensitive index (ISI) and Homeostasis model assessment of IR (HOMA-IR) were applied, miR-21 and TGF-β1/smads mRNA expression were examined by RT-PCR, smad3 and smad7 protein were detected by western-blotting and laser scanning confocal microscopy (LSCM), the valid target of miR-21 was detected by luciferase reporter gene assay. Here, we found that metformin dose-dependently decreased miR-21 expression, accompanied by the decrease of HOMA-IR and the increase of HOMA-ISI. Luciferase report gene assay showed that smad7 was an effective target of miR-21. miR-21 overexpression directly downregulated smad7 and indirectly upregulated smad3 expression. Interestingly, miR-21 expression positively correlated with HOMA-IR and negatively correlated with HOMA-ISI. In conclusion, our results demonstrated that metformin improved IRSM by inhibiting miR-21 expression, and that miR-21 may be one of the therapeutic targets for IR.
胰岛素抵抗（IR）在腹型肥胖、高血压、冠心病、动脉粥样硬化和糖尿病的发病机制中起主要作用。miR-21与TGF-β/smads密切相关。然而，二甲双胍是否通过调节miR-21及其靶信号TGF-β1/smads表达来改善骨骼肌胰岛素抵抗（IRSM）仍不清楚。在本研究中，建立了IR模型的高脂饮食大鼠和IR-骨骼肌L6细胞（L6-SMCs）模型，应用胰岛素敏感指数（ISI）和IR的稳态模型评估（HOMA-IR），通过RT-PCR检测miR-21和TGF-β1/smads mRNA表达，通过蛋白质免疫印迹法和激光扫描共聚焦显微镜（LSCM）检测smad3和smad7蛋白，通过荧光素酶报告基因检测法检测miR-21的有效靶标。在此，我们发现二甲双胍剂量依赖性地降低miR-21表达，同时HOMA-IR降低，HOMA-ISI升高。荧光素酶报告基因检测显示smad7是miR-21的有效靶标。miR-21过表达直接下调smad7并间接上调smad3表达。有趣的是，miR-21表达与HOMA-IR呈正相关，与HOMA-ISI呈负相关。总之，我们的结果表明二甲双胍通过抑制miR-21表达改善IRSM，并且miR-21可能是IR的治疗靶点之一。
