METTL7B对人肝细胞脂滴形成的影响

Effect of METTL7Bon formation of lipid droplets in human hepatocytes

目的探讨甲基转移酶样蛋白7B(METTL7B)对人肝细胞脂滴形成的影响。方法取5只8~10周龄雄性C57BL/6J小鼠的心、肝、脑、肺、肾、肌肉、皮肤等组织,检测组织中METTL7B蛋白表达情况。用不同浓度油酸(0、0.25、0.5、1.0mmol/L)处理人正常肝细胞LO2,采用CCK-8法检测细胞活力,油红O染色检测细胞内脂滴含量。METTL7BsiRNA转染LO2细胞,检测LO2细胞内脂滴含量以及三酰甘油和胆固醇代谢相关基因的表达情况。结果METTL7B蛋白在小鼠肝脏组织中表达最高,在其他器官组织中表达较弱或不表达。与油酸0mmol/L比较,油酸1.0mmol/L能降低细胞活力(P<0.05)。油酸0.5mmol/L处理后,细胞内脂滴含量增多,且脂滴大小清晰,METTL7BmRNA和蛋白表达升高(P<0.05)。干扰METTL7B后,细胞内脂滴含量减少(P<0.05),三酯甘油代谢相关基因载脂蛋白B100、Runt相关转录因子2、硬脂酰辅酶A去饱和酶mRNA表达上调(P<0.05),胆固醇代谢相关基因肉毒碱棕榈酰转移酶、胆固醇调节元件结合蛋白1(SREBP1)、SREBP2mRNA表达下调(P<0.05)。结论METTL7B与人肝细胞脂滴形成密切相关,主要通过上调三酰甘油代谢相关基因和下调胆固醇代谢相关基因的表达来发挥作用。

Objective To investigate the effect of methyltransferase like 7B(METTL7B)on the formation of lipid droplets in human hepatocytes.Methods The protein expression of METTL7B was detected in the heart,liver,brain,lung,kidney,muscle and skin tissues in five male C57BL/6Jmice aged from 8to 10weeks.The normal human hepatocyte LO2was treated with different concentrations of 0,0.25,0.5and 1.0mmol/L oleic acid.The cell viability was detected by CCK-8method,and the content of intracellular lipid droplets was detected by oil red O staining.The LO2cells were transfected with METTL7BsiRNA,and the content of intracellular lipid droplets and the expressions of triglyceride and cholesterol metabolism related genes were detected.Results The protein expression of METTL7Bwas highly expressed in the liver,but weakly or unexpressed in the other organ tissues.Compared with oleic acid 0mmol/L,oleic acid 1.0 mmol/L decreased cell viability(P<0.05).After treated with oleic acid 0.5mmol/L,the content of intracellular lipid droplets was increased,the size of lipid droplets was clear,and the mRNA and protein expressions of METTL7B were increased(P<0.05).After the interference with METTL7B,the content of intracellular lipid droplets was reduced(P<0.05),the mRNA expressions of triglyceride metabolism related genes apolipoprotein B100,runt-related transcription factor 2and stearoyl-CoA desaturase were upregulated,and those of cholesterol metabolism related genes carnitine palmitoyltransferase 1,sterol regulatory element binding protein 1(SREBP1)and SREBP2 were downregulated(P<0.05).Conclusion METTL7Bis closely related to the formation of lipid droplets in human hepatocytes,mainly by upregulating the expressions of the genes related to triglyceride metabolism and downregulating the expressions of the genes related to cholesterol metabolism.