Transcription factor C/EBPβ promotes the transcription of the porcine GPR120 gene

G protein-coupled receptor 120 (GPR120), an adipogenic receptor critical for the differentiation and maturation of adipocytes, plays an important role in controlling obesity in both humans and rodents and, thus, is an attractive target of obesity treatment studies. However, the mechanisms that regulate the expression of porcine GPR120 remain unclear. In this study, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) techniques were used to analyze and identify the binding of C/EBPb (transcription factor CCAAT/enhancer binding protein beta) to the GPR120 promoter. C/EBPb overexpression and RNA interference studies showed that C/EBPb regulated GPR120 promoter activity and endogenous GPR120 expression. The binding site of C/EBPb in the GPR120 promoter region from K101 to K87 was identified by promoter deletion analysis and site-directed mutagenesis. Overexpression of C/EBPb increased endogenous GPR120 expression in pig kidney cells (PK). Furthermore, when endogenous C/EBPb was knocked down, GPR120 mRNA and protein levels were decreased. The stimulatory effect of C/EBPb on GPR120 transcription and its ability to bind the transcription factor-binding site were confirmed by luciferase, ChIP, and EMSA. Moreover, the mRNA and protein expression levels of C/EBPb were induced by high fat diet feeding. Taken together, it can be concluded that C/EBPb plays a vital role in regulating GPR120 transcription and suggests HFD-feeding induces GPR120 transcription by influencing C/EBPb expression.