The Role Of MiR379 In Liraglutide Improving Diabetes-associated Nonalcoholic Fatty Liver Disease

Objective: In recent years,accumulated studies have shown that abnormal expression of micro RNAs is closely related to lipid metabolism disorder in liver.Liraglutide can obviously improve hepatic steatosis and lipid metabolism disorder in NAFLD.However,the role of micro RNAs in Liraglutide improving NAFLD remains largely unclear.Therefore,we aim to explore the role and mechanism of miR379 in the improvement of NAFLD by liraglutide.Methods: 1.Male C57BL/6J mice at age of 6 weeks were fed with high fat diet for 2 weeks.Except for the control group,the diabetes-associated NAFLD mice model was established by intraperitoneal injection of streptozotocin.After successful modeling,the mice were randomly divided into two groups: diabetes mellitus(DM)group and liraglutide(Lira)group.After 10 weeks of high fat feeding,mice of Lira group were injected with liraglutide once a day for another 4 weeks.After 16 weeks,hepatic H&E and oil red O staining were used to detect liver pathology,the hepatic lipid content was detected by triglyceride(TG)assay kit,the expression levels of miR379?IGF1?SREBP1c?FAS and ACC m RNA in liver were measured by fluorescence quantitative PCR,the protein expression levels of AKT and p-AKT were assessed by western blot.2.Human Hep G2 cell lines were cultured in vitro and divided into five groups: control(NC)group,palmitic acid(PA)group,liraglutide(Lira)group,liraglutide miR379 mimic NC(Lira NC)group and liraglutide miR379 mimic(Lira miR379 mimic)group.Except for the control group,all the others were treated with 0.25 m M PA to establish NAFLD cell model in vitro,and liraglutide was given to each drug group.miR379 mimic and miR379 mimic NC were transfected into Hep G2 cells.The levels of TG in Hep G2 cells in each group were detected by TG assay kit.The m RNA expression levels of miR379,IGF1,SREBP1 c,FAS and ACC were evaluated by fluorescence quantitative PCR,and the protein expression levels of AKT and p-AKT were measured by western blot.miR379 mimic/inhibitor was transfected into Hep G2 cells.The m RNA expression levels of IGF1,SREBP1 c,FAS and ACC were evaluated by fluorescence quantitative PCR.Results: 1.H&E and oil red O staining of liver tissue showed that,compared with the control group,DM induced significantly hepatocyte vacuolar degeneration and large amount of lipid droplet in hepatocytes,and liraglutide sharply decreased hepatocyte vacuolar degeneration and lipid accumulation.The TG levels of DM and PA groups were significantly elevated(P<0.05),and significantly decreased after liraglutide treatment(P<0.05).2.Compared with the control group,the expression levels of miR379 in DM and PA groups were increased(P<0.05),m RNA expression levels of IGF1 were decreased(P<0.05),the protein expression of p-AKT was decreased and m RNA expression levels of SREBP1 c,FAS and ACC were increased(P<0.05).After liraglutide treatment,miR379 was decreased(P<0.05),IGF1 m RNA expression levels were increased(P<0.05),the protein expression of p-AKT was increased,and m RNA expression levels of SREBP1 c,FAS and ACC1 were reduced(P<0.05).Compared with the Lira NC group,TG content was significantly increased in the Lira miR379 mimic group(P<0.05),miR379 expression level was increased(P<0.05),the expression levels of IGF1 m RNA and p-AKT protein were reduced(P<0.05),m RNA expression levels of SREBP1 c,FAS and ACC were increased(P<0.05)? 3.When miR379 was overexpressed,the m RNA expression levels of IGF1 were decreased(P<0.05);When miR379 expression was inhibited,the m RNA expression levels of IGF1 were increased(P<0.05).4.When miR379 expression was inhibited,the levels of TG and the expression levels of miR379 in hepatocytes were decreased(P<0.05),the m RNA expression levels of IGF1 were increased(P<0.05),the protein expression levels of p-AKT were increased,and the m RNA expression levels of SREBP1 c,FAS and ACC were decreased(P<0.05).Conclusions: 1.Liraglutide significantly reduced hepatocyte steatosis and lipid droplet deposition in NAFLD models in vitro and in vivo.2.Liraglutide alleviated hepatic TG accumulation by downregulating the expression of miR379.3.miR379 specifically targeted the gene IGF1.4.Liraglutide may attenuate hepatic steatosis and TG accumulation in NAFLD through the miR379-mediated IGF1/PI3K/AKT signaling pathway.