BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is a global metabolism-associated liver disease.Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a newly discovered secreted protein that is involved in...BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is a global metabolism-associated liver disease.Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a newly discovered secreted protein that is involved in metabolic homeostasis.However,much remains to be discovered about its function in hepatic lipid metabolism;thus,we assessed whether MANF could regulate hepatic metabolism.AIM To establish in vivo and in vitro NAFLD models to explore the role of MANF in hepatic lipid metabolism.METHODS HepG2 cells treated with free fatty acids (FFAs) and ob/ob mice were used as NAFLD models.Liver tissues collected from wild type and ob/ob mice were used to detect MANF expression.Cells were treated with FFAs for different durations.Moreover,we used lentiviral constructs to establish overexpression and knockdown cell models in order to interfere with MANF expression levels and observe whether MANF influences hepatic steatosis.Western blot analysis and quantitative real-time PCR were used to detect protein and gene expression,and oil red O staining was used to visualize intracellular lipid droplets.RESULTS Hepatic MANF protein and mRNA expression in wild type mice were 10-fold and 2-fold higher,respectively,than those in ob/ob mice.The MANF protein was temporarily increased by 1.3-fold after stimulation with FFAs for 24 h and gradually decreased to 0.66-fold that of the control at the 72 h time point in HepG2 cells.MANF deficiency upregulated the expression of genes involved infatty acid synthesis,cholesterol synthesis,and fatty acid uptake and aggravated HepG2 cell steatosis,while MANF overexpression inhibited fatty acid synthesis and uptake and cholesterol synthesis,and rescued HepG2 cells from FFAsinduced steatosis.Furthermore,a significant decrease in triglyceride levels was observed in the MANF overexpression group compared with the control group(0.4288±0.0081 mmol/g vs 0.3746±0.0121 mmol/g,P <0.05) upon FF As treatment.There was also a 17%decrease in intracellular total cholesterol levels between the MANF overex展开更多
基金Supported by National Natural Science Foundation of China,No.81300702 and No.81501199Natural Science Foundation Project of Chongqing CSTC,No.cstc2018jcyj AX0210 and No.cstc2017jcyj AX0016the Kuanren Talents Program of the Second Affiliated Hospital of Chongqing Medical University
文摘BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is a global metabolism-associated liver disease.Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a newly discovered secreted protein that is involved in metabolic homeostasis.However,much remains to be discovered about its function in hepatic lipid metabolism;thus,we assessed whether MANF could regulate hepatic metabolism.AIM To establish in vivo and in vitro NAFLD models to explore the role of MANF in hepatic lipid metabolism.METHODS HepG2 cells treated with free fatty acids (FFAs) and ob/ob mice were used as NAFLD models.Liver tissues collected from wild type and ob/ob mice were used to detect MANF expression.Cells were treated with FFAs for different durations.Moreover,we used lentiviral constructs to establish overexpression and knockdown cell models in order to interfere with MANF expression levels and observe whether MANF influences hepatic steatosis.Western blot analysis and quantitative real-time PCR were used to detect protein and gene expression,and oil red O staining was used to visualize intracellular lipid droplets.RESULTS Hepatic MANF protein and mRNA expression in wild type mice were 10-fold and 2-fold higher,respectively,than those in ob/ob mice.The MANF protein was temporarily increased by 1.3-fold after stimulation with FFAs for 24 h and gradually decreased to 0.66-fold that of the control at the 72 h time point in HepG2 cells.MANF deficiency upregulated the expression of genes involved infatty acid synthesis,cholesterol synthesis,and fatty acid uptake and aggravated HepG2 cell steatosis,while MANF overexpression inhibited fatty acid synthesis and uptake and cholesterol synthesis,and rescued HepG2 cells from FFAsinduced steatosis.Furthermore,a significant decrease in triglyceride levels was observed in the MANF overexpression group compared with the control group(0.4288±0.0081 mmol/g vs 0.3746±0.0121 mmol/g,P <0.05) upon FF As treatment.There was also a 17%decrease in intracellular total cholesterol levels between the MANF overex
