赖氨酸甲基化酶SET7对细胞葡萄糖摄取能力的影响

Effects of lysine methyltransferase SET7 on glucose uptake in cells

[目的]探讨SET甲基转移酶7(SET domain containing lysine methyltransferase 7,SET7)对葡萄糖转运载体4(glucose transporter 4,GLUT4)甲基化水平及细胞葡萄糖摄取能力的影响。[方法]通过蛋白甲基化及短肽甲基化实验,明确SET7对GLUT4的甲基化位点;在人胚肾上皮细胞293T中通过siRNA手段沉默SET7蛋白的表达水平,并分别通过蛋白免疫印迹和2-脱氧-^3H-D-葡萄糖掺入实验检测GLUT4蛋白在细胞内的亚定位及其对细胞葡萄糖摄取能力的影响。[结果]蛋白甲基化实验表明SET7能够促使GLUT4(1~100aa)这一片段发生甲基化,进一步的短肽甲基化实验证实SET7能够促使GLUT4-K50位点发生单甲基化(K50me);沉默SET7后可限制细胞浆中的GLUT4转移至细胞膜;与对照组相比,SET7沉默组细胞葡萄糖摄取效率降低了76%,经t检验分析,这种差异有统计学意义(P<0.001)。[结论]SET7可促进GLUT4-K50位点发生单甲基化,沉默SET7后可限制细胞浆中的GLUT4转移至细胞膜,并降低细胞对葡萄糖的摄取。

[Objective]To investigate the effect of SET7 on the methylation level of GLUT4 and cellular glucose uptake.[Method]The protein methylation and short peptide methylation experiments were performed to determine the methylation sites of GLUT4 by SET7;The subcellular localization of GLUT4 and the cellular glucose uptake was detected by immunoblotting and2-deoxy-^3H-D-glucose incorporation assay,respectively.[Result]The protein methylation experiments showed that SET7 could methylate the GLUT4(1-100)segment,and the short peptide methylation experiments confirmed that SET7 could methylate the K50 of GLUT4(K50 me);Silence of SET7 could restrict GLUT4 to the cell membrane;Compared to the control group,the cellular glucose uptake in SET7 silenced group reduced by 76%.And the difference was statistically significant through t test(P<0.001).[Conclusion]SET7 could methylate the K50 of GLUT4(K50 me).Silence of SET7 could restrict GLUT4 to the cell membrane and reduce the cellular glucose uptake.