miR-335靶定ENPP4和FADS1基因介导高脂性小鼠肥胖

miR-335 targets ENPP4 and FADS1 genes to mediate obesity in high-fat mice

目的研究高脂饮食小鼠腹脂微小RNA(miRNA)的差异表达,探讨高表达miR-335在脂类代谢过程中作用。方法对高脂饮食的小鼠腹脂进行miRNA芯片分析,检测小鼠腹脂miRNA的差异表达;采用生物信息学方法预测miR-335靶基因,双荧光素酶报告系统及点突变实验验证靶基因外核苷酸焦磷酸酶/磷酸二酯酶4(ectonucleotide pyrophosphatase/phosphordiester-ase4,ENPP4)和脂肪酸去饱和酶1(fatty acid desaturase1,FADS1);3T3L1细胞中转染miR-335模拟体,检测靶基因mRNA和蛋白表达量;实时荧光定量PCR检测miR-335和靶基因在高脂饮食小鼠不同组织中的表达量。结果高脂饮食后,模型组小鼠体型明显大于对照组,小鼠血清总胆固醇(P=0.016)和三酰甘油(P=0.014)水平显著上升。高脂饮食的小鼠脂肪组织中多种miRNA发生差异表达,其中miR-335表达上升尤为明显(P=0.024)。通过Targetscan预测miR-335靶基因,结合其功能,筛选出ENPP4和FADS1。报告基因试验显示miR-335通过"种子区"与ENPP4和FADS1预测靶位点结合从而抑制ENPP4和FADS1基因的表达,点突变实验证实了结合的靶位点;设计合成miR-335模拟体转染3T3L1细胞,培养48 h后,FADS1 mRNA表达水平显著下降(P=0.038),ENPP4和FADS1蛋白水平均显著下降(P=0.033,P=0.007)。与对照组相比,高脂饮食后miR-335在肝脏、白棕脂肪组织和脑中显著性高表达(P=0.017,P=0.002,P=0.003,P=0.031);而ENPP4和FADS1在脑(P=0.006,P=0.034)和棕色脂肪组织(P=0.014,P=0.037)中表达量显著下降,同时ENPP4在肝脏中的表达量也极显著下降(P<0.001)。结论miR-335是与脂类代谢和脂肪沉积相关的miRNA,ENPP4和FADS1基因是miR-335的靶基因。

Objective To detect the differential expression of microRNA(miRNA)in abdominal fat of mice fed with high fat and to explore the role of highly expressed miR-335 in lipid metabolism.Methods MicroRNA microarray was used to detect the differential expression of miRNAs in abdominal fat of mice fed with high fat.The target genes of miR-335 were predicted by Targetscan,the target genes of ectonucleotide pyrophosphatase/phosphordiester-ase 4(ENPP4)and fatty acid desaturase1(FADS1)were verified with double luciferase reporter system and point mutation test.miR-335 mimics was transfected into 3T3L1 cells to detect the expression of target gene mRNA and protein;Realtime PCR was used to detect the expression levels of miR-335 and target genes in different tissues of mice.Results After high-fat feeding,the size of mice in the model group was significantly larger than the control group,and the serum total cholesterol and triglyceride levels of mice were significantly increased(P=0.016,P=0.014).miRNAs were differentially expressed in adipose tissues of mice fed with high fat,and the expression of miR-335 increased significantly(P=0.024).Double luciferase reporter system showed that miR-335 combined with the predicted target sites of ENPP4 and FADS1 through the"seed region"to inhibit the expression of ENPP4 and FADS1 genes,and the point mutation test confirmed the binding target sites between miR-335 and ENPP4/FADS1.MiR-335 mimics were transfected into 3T3L1 cells,the expression level of FADS1 mRNA decreased significantly(P=0.038),and the protein levels of ENPP4 and FADS1 decreased significantly(P=0.033,P=0.007).Realtime PCR showed that,miR-335 was significantly higher expressed in liver,brown adipose tissue,and brain after high-fat feeding,especially in white adipose tissue(P=0.002).The expression of ENPP4 and FADS1 in brain(P=0.006,P=0.034)and brown adipose tissue(P=0.014,P=0.037)decreased significantly,and the expression of ENPP4 in liver also decreased significantly after high-fat diet(P<0.001).Conclusion miR-335 is a miRNA related to lipid metabolism and fat deposition.ENPP4 and FADS1 are the target genes of miR-335.