The Regulation Of LPS Induced Inflammation In Liver Cells By FGF21

Obesity initiate a variety of metabolic diseases, such as type 2 diabetes, non-alcoholic fatty liver disease, high blood pressure, and those metabolic diseases have become the focus of global attention. Research shows that obesity is a chronic inflammatory state. In recent years, a significant progress made by the study of metabolism is that found a close association between obesity and inflammation,and inflammation is mediated by a variety of metabolic diseases caused by obesity. FGF21 is a newly discovered adipocytokines, study reveal that FGF21 is an important factor that can resistant obesity, improve insulin resistance state and various metabolic diseases. However, the mechanism of the FGF21 involved in metabolic regulation and its relationship with inflammatory pathways is still unclear. Thus, in this study we attempted to investigate the relationship between FGF21 and inflammation, and its transcriptional regulation by NF-κB, aimed at clarify the mechanism of FGF21 resist obesity and metabolic disease. This can provide experimental basis to control the occur and development of the obesity and metabolic diseases effectively.This experiment were conducted in HEK293A cells, using the dual luciferase reporter system, real-time PCR, ChIP experiments to verify the transcription of FGF21 was regulated by functional subunit of NF-κB p65, a key transcription factor in inflammation. Over-expression FGF21 in HepG2 cells, assess the expression of inflammation-related genes, through the method of real-time PCR and Western Blot. In our study, it suggested the anti-inflammatory effects of FGF21 in HepG2 cells. The results are as follows:1. The inflammatory stimuli LPS, TNFa, can repress the transcriptional expression of FGF21 in HepG2 cells.In addition, LPS can inhibit the transcriptional expression of FGF21 through NF-κB.2. Bioinformatics analysis predicted the presence of NF-κB binding sites on the FGF21 gene promoter. The NF-κBp65 can suppress the promoter activity of FGF21 by using the dual luciferase reporter system. Over expression p65 in HepG2 cells and HEK23A cells, the mRNA levals of FGF21 was significantly reduced.3. In order to explore the sites which NF-κBp65 bind to FGF21 promoter.We constructed truncated and point mutant promoter in the vector, for the prediction of the three NF-κB binding sites. Our experiments show that the predicted NF-κB binding site -344/-332bp of FGF21 is critical for NF-κBp65 regulation.4. Finally, using chromatin immunoprecipitation,we demonstrated that the NF-κBp65 inhibit FGF21 gene transcription by binding to the NF-κB binding site-344/-332bp of FGF21.5. Overexpression FGF21 in HepG2 cells, we studied that FGF21 significant inhibit the transcription and translation of NF-κBp65 by using real-time PCR and Western Blot. And we also detect the transcription of inflammation-related genes, we found that TNFa, IL6 and CRP were significantly suppressed. FGF21 also can attenuate LPS-induced p65, TNFa, IL6 transcriptional upregulation.