Inhibition of silent information regulator 1 induces glucose metabolism disorders of hepatocytes and enhances hepatitis C virus replication / 中华传染病杂志

ABSTRACT

Objective The aim of this study was to investigate the effect of hepatitis C virus (HCV) replication on expression of silent information regulator 1 (SIRT1) and glucose metabolism of hepatocytes using Huh 7.5 cells harboring HCV replicon.Methods The level of reactive oxygen species (ROS),value of nicotinamide adenine dinucleotide (NAD+)/reduced form of nicotinamide adenine dinucleotide (NADH) was detected by flow cytometry and chromatometry.The activity,mRNA expression,and protein level of SIRT1 were detected by a scintillation counter,real-time fluorescence quantitative polymerase chain reaction (RT-PCR),and Western blot,respectively.Glucose uptake by hepatocytes and gluconeogenesis were detected using radioactive isotope method and glucose oxidase method.The mRNA levels of SIRT1 downstream glucose-metabolism genes were measured by RT-PCR.Measurement date were compared by t test.Results In replicon cells,the level of ROS (3.8±0.5 vs 1.0±0.2; t=12.736,P＜0.01) was increased and the value of NAD+/NADH (0.03±0.01 vs 0.12±0.03; t=6.971,P＜0.01) decreased compared with Huh 7.5 cells.The activity (0.3±0.1 vs 1.0±0.2; t=7.668,P＜0.01),mRNA expression(0.4±0.1 vs 1.0± 0.3; t=4.648,P＜0.01) and protein level(0.3±0.1 vs 0.8±0.2; t=5.941,P＜0.01) of SIRT1 were reduced.Inhibition of SIRT1 not only increased insulin receptor substrate-1 (IRS-1) phosphorylation (0.7±0.2 vs 0.4±0.1; t=3.286,P＜0.01),decreased protein kinase B (Akt) phosphorylation (0.3 ± 0.1 vs 0.6 ± 0.2; t=3.286,P＜0.01),down regulated cell surface expression of glucose transporler 2 (GLUT2,0.4±0.1 vs 1.0 ± 0.2; t =6.573,P＜0.01) and suppressed cellular glucose uptake (count per minute4600±500 vs 21 000±4600; t=8.682,P＜0.01); but also decreased phosphorylation of forkhead box O1 (FoxO1,0.2＝0.1 vs 0.5±0.1; t=5.196,P＜ 0.01),up-regulated phosphoenolpyruvate carboxykinase (PEPCK,2.8±0.6 vs 1.0±0.3; t=6.573,P＜0.01) and glucose 6-phosphatase (2.6±0.5 vs 1.0±0.2; t=7.278,P＜0.01) genes,and promoted glucose production (2.5±0.5 vs 1.0±0.2; t=5.543,P＜0.01).Conclusions HCV replication decreases NAD+/NADH ratio,which might down-regulate the activity and the expression of SIRT1,leading to changes in the expression profile of glucose metabolism related genes and causing glucose metabolism disorders of hepatocytes by a decrease in glucose uptake and an increase in glucose production,and promotes HCV replication.