
RNA m6A甲基化修饰在脂肪细胞胰岛素抵抗中的作用机制
叶棣文, 张炳杨, 张丹彤, 马万山, 逯素梅
RNA m6A甲基化修饰在脂肪细胞胰岛素抵抗中的作用机制
The role of RNA m6A methylation in insulin resistance in adipocytes
目的 探讨RNA m6A甲基化修饰在脂肪细胞胰岛素抵抗中的作用及机制。 方法 收集2型糖尿病患者术中赘余皮下脂肪组织,以非2型糖尿病患者同样组织为对照,检测组间RNA m6A水平。高脂饮食诱导C57BL/6J小鼠构建胰岛素抵抗(insulin resistance,IR)模型(HFD组,n=5,60%高脂饲料喂养16周),对照组10%低脂饲料喂养16周(CD组,n=5)。模型构建成功后,取附睾周围脂肪组织行表观转录组学m6A甲基化修饰芯片检测,并借助MeRIP-qPCR实验、RT-qPCR以及RNA结合蛋白免疫沉淀测定(RNA Binding Protein Immunoprecipitation Assay,RIP)实验验证胰岛素信号转导相关基因变化;进一步观察METTL3小分子抑制剂STM2457对高脂饮食诱导下小鼠胰岛素信号转导基因的影响。 结果 2型糖尿病患者和小鼠IR模型脂肪组织中总体m6A修饰水平均升高(患者200 ng RNA t=-8.375,P<0.001;患者100 ng RNA t=-3.722,P=0.006;患者50 ng RNA t=-4.937;P=0.001;小鼠100 ng RNA t=-3.590,P=0.023;小鼠50 ng RNA t=-2.760,P=0.025)。表观转录组学检测证实IR的脂肪组织中1 175个基因发生高m6A修饰,55个基因发生低m6A修饰,同时有182个基因呈现高m6A修饰且低表达,包括AKT2、INSR、PIK3R1、ACACA、SREBF1等5个胰岛素信号转导关键基因,其中AKT2、INSR、ACACA、SREBF1等4个基因被确证并证实其与METTL3存在直接结合,其m6A修饰水平受METTL3正向调控。STM2457作用下,胰岛素敏感性提高,且AKT2、INSR、ACACA、SREBF1转录水平上调,提示IR表型改善明显。 结论 高脂饮食通过METTL3诱导脂肪细胞胰岛素信号转导基因AKT2、INSR、ACACA、SREBF1发生m6A高甲基化修饰,诱导其低表达,阻滞胰岛素信号转导,进而参与诱发IR。
Objective To explore the role of RNA m6A methylation in insulin resistance in adipocytes. Methods We collected redundant subcutaneous adipose tissue samples from patients with type 2 diabetes and patients without type 2 diabetes to measure the RNA m6A modification level. A insulin resistance(IR) model was established by feeding C57BL/6J mice with a 60% high-fat diet for 16 weeks(n=5),while the control group was fed with a 10% low-fat diet for 16 weeks(n=5). After successful modeling,the adipose tissue around the epididymis was taken to detect m6A methylation using epitranscriptomic microarrays. The changes in insulin signaling-related genes were determined by MeRIP-qPCR assay,RT-qPCR,and RIP assay. The effects of the small-molecule inhibitor STM2457 targeting methyltransferase like 3(METTL3) on insulin signaling-related genes in mice feeding a high-fat diet were investigated. Results The overall m6A modification levels were significantly increased in the adipose tissue of patients with type 2 diabetes and IR mice(patients 200 ng RNA,t=-8.375,P<0.001;patients 100 ng RNA,t=-3.722,P=0.006;patients 50 ng RNA,t=-4.937,P=0.001;mice 100 ng RNA,t=-3.590,P=0.023;mice 50 ng RNA,t=-2.760,P=0.025). The epitranscriptomic assay detected high m6A methylation levels in 1 175 genes and low m6A methylation levels in 55 genes;182 genes showed significantly high m6A modification and low expression,including five key insulin signaling-related genes(AKT2,INSR,PIK3R1,ACACA,and SREBF1). Direct binding between AKT2,INSR,ACACA,and SREBF1 and METTL3 was validated,and their m6A modification levels were positively regulated by METTL3. STM2457 significantly increased insulin sensitivity,and significantly upregulated the transcriptional levels of AKT2,INSR,ACACA,and SREBF1,suggesting a significant improvement in IR phenotype. Conclusion High-fat diet induces IR through METTL3,which mediates m6A hypermethylation of AKT2,INSR,ACACA,and SREBF1 to downregulate their expression and block insulin signaling in adipocytes.
高脂饮食 / 胰岛素抵抗 / RNA m6A甲基化修饰 / 胰岛素信号转导通路
high-fat diet / insulin resistance / RNA m6A methylation / insulin signaling pathway
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