Study Of The Effect And Mechanism Of Up-frameshift Protein 1 In Nonalcoholic Fatty Liver Disease

Backgroud:The prevalence of Nonalcoholic fatty liver disease (NAFLD) were incresed recently, NAFLD has become a common chronic liver disease worldwide. However, its pathogenesis is not well unknown so far. UPF1 is well known as a protein for its central role in nonsense-mediated mRNA decay (NMD) pathway. Recent studies have clarified that UPF1 contributes to DNA replication and DNA damage. NMD and DNA damage are connected to the lipid metabolism in the liver and the hepatocyte damage. Yet, it is not clear that whether UPF1 plays a role in the pathogenesis of NAFLD.Objective:In this study, we examined NAFLD cell models in L02 cell and NAFLD mice model, plan to find the relationship between UPF1 and NAFLD.Methods:The animal model of NAFLD (experimental group) was established by feeding C57BL/6 mice with 5-weeks MCD diet. The vitro model of NAFLD is established with L02 cells induced with FFA (palmitic oil:oleic oil=1:2). Oil red 0 staining was to observe lipid droplets, and determine the content of the TG in frozen solution.Real-time fluorescent quantitative PCR (SYBR method) was used to detect UPF1 mRNA in mice liver tissue and L02 cells induced by FFA. Then analyze the expression of UPF1 mRNA in respective two groups of mice and L02 cells.Western Blot was performed after total protein extraction from mice liver and L02 cells. We observed the UFP1 protein in the treatment group and the control group, in order to confirm whether the changes are corresponding with the mRNA changes.Interference of siRNA was used to inhibit the UPF1 expression in L02 cells. Then, we observed the expression of UPF1, PGC1a, PPARa CPT1a and ROS in L02 cells. In addtion, Discussion was made to find the relationship between UPF1 and NAFLD.Results:1. The mRNA and protein expression of UPF1 in the L02 cells induced by FFA were significantly lower than the control. The mRNA and protein levels of UPF1 in the MCD mice group were significantly decresed than the control.2. Intracellular TG contents were increased after the inhibition of UPF1.3.The expression of PGC1a mRNA, PPARa mRNA, CPT1a mRNA were down-regulated after the inhibition of UPF1.4. The levels of ROS was increased after the inhibition of UPF1.Conclusion:The results suggest that UPF1 may play a certain protection role in NAFLD development. Inhibition of UPF1 may be the pathogenesis of NAFLD. The mechanisms may be its roles in down-regulation of PGC1a, PPARa, CPT1a, and up-regulation of ROS levels.