胃饥饿素通过miR-455-5p靶向IGF-1R调控肝细胞胰岛素敏感性的作用及机制研究

Ghrelin regulates insulin resistance by targeting insulin-like growth factor-1 receptor via miR-455-5p in hepatic cells

目的:探究胃饥饿素通过调控miR-455-5p影响肝细胞胰岛素敏感性的作用机制。方法:采用高糖构建HepG2细胞胰岛素抵抗模型,造模成功后使用去酰基化胃饥饿素(DAG,1μmol/L)干预,分别转染miR-455-5p模拟物(miR-455-5p mimic)或对照物(NC mimic)。检测各组细胞葡萄糖消耗量和细胞内糖原含量。采用荧光原位杂交分析HepG2细胞内miR-455-5p表达水平。应用生物信息学分析、荧光素酶报告基因实验来鉴定与miR-455-5p结合的靶基因,Western Blot检测IGF-1R/PI3K/Akt信号通路的表达水平。结果:在胰岛素抵抗HepG2细胞中,miR-455-5p的表达水平显著上调,葡萄糖消耗量和细胞内糖原含量均明显降低。DAG干预后细胞葡萄糖消耗量和细胞内糖原含量增加,miR-455-5p的表达水平下调,IGF-1R/PI3K/Akt信号通路被激活。生物信息学分析表明IGF-1R是miR-455-5p的靶基因。双荧光素酶报告基因检测、miR-455-5p模拟物和抑制剂转染证实DAG通过抑制miR-455-5p从而激活IGF-1R/PI3K/Akt信号通路。结论:DAG通过miR-455-5p介导的IGF-1R/PI3K/Akt信号通路激活并改善胰岛素抵抗,表明抑制miR-455-5p或外源性补充DAG可能是T2DM治疗的潜在靶点。

Objective:To explore the mechanism by which ghrelin regulates insulin sensitivity through modulation of miR-455-5p in hepatic cells.Methods:HepG2 cells were treated with or without Ghrelin(DAG)(1μmol/L).Glucose consumption,intracellular glycogen content,phosphorylation of PI3K and Akt stimulated by insulin,expression of miR-455-5p,as well as IGF-1R protein level were analyzed.In addition,bioinformatic analysis,dual luciferase reporter assay,miR-455-5p mimic or inhibitor treatment were conducted to investigate the molecular mechanisms.Results:High glucose treatment upregulated miR-455-5p expression but reduced glucose consumption and glycogen content.DAG reversed the effect of high glucose on glucose metabolism,increased protein level of IGF-1R and phosphorylation of PI3K/Akt stimulated by insulin,as well as downregulated miR-455-5p expression.Bioinformatic analysis indicated IGF-1R was the target of miR-455-5p.Dual luciferase reporter assay,as well as transfection with miR-455-5p mimic/inhibitor confirmed that DAG activated the IGF-1R/PI3K/Akt signaling via inhibiting miR-455-5p.Conclusion:DAG improves insulin resistance via miR-455-5p-mediated activation of the IGF-1R/PI3K/Akt signaling,suggesting that suppression of miR-455-5p or activation of DAG may be potential targets for T2DM therapy.