The link between fibroblast growth factor 21 and sterol regulatory element binding protein 1c during lipogenesis in hepatocytes.

Recently fibroblast growth factor 21 (FGF21) has been identified as a potent regulator in glucose and lipid homeostasis. Here, we firstly investigated the metabolic role of FGF21 in human liver-derived HepG2 cells, and suggested that overexpression of FGF21 suppressed triglyceride accumulation by inhibiting the transcription of the gene necessary for de novo lipogenesis. The potential mechanism of FGF21 regulating lipogenesis was also explored, which revealed that FGF21 repressed the transcription of sterol regulatory element binding protein 1c (SREBP1c), an essential transcription factor promoting expression of lipogenesis-related genes. Overexpression of FGF21 ameliorated the up-regulation of SREBP1c and fatty acid synthase (FAS) in HepG2 cells elicited by FFAs treatment. Moreover, FGF21 could inhibit the transcriptional levels of the key genes involved in processing and nuclear translocation of SREBP1c, and decrease the protein amount of mature SREBP1c. Unexpectedly, overexpression of SREBP1c in HepG2 cells could also inhibit the endogenous FGF21 transcription. Further experiments demonstrated that SREBP1c could significantly attenuate the promoter activity of FGF21. In conclusion, our data identifies a clear link between FGF21 and SREBP1c during lipogenesis in hepatocyte in culture.