Fat mass and obesity associated (FTO) gene regulates gluconeogenesis in chicken embryo fibroblast cells

Fat mass and obesity-associated (FTO) gene was found to be associated with energy homeostasis in mammals, yet the function of chicken FTO is less clear. In this study, chicken embryo fibroblast cells (DF-1) were transiently transfected to over-express (FTO+) or to knockdown (FTO−) the chicken FTO gene and were used for the functional analysis. FTO expression was significantly augmented in FTO+ cells while depressed in FTO− cells (P < 0.05). FTO+ cells had significantly lower glucose yet higher lactic acid (LD) concentrations (P < 0.05) in the culture media, which was associated with significantly up-regulated (P < 0.05) mRNA expression of the rate-limiting gluconeogenic enzymes, glucose-6-phosphatase (G6PC) and the phosphoenolpyruvate carboxykinase-mitochondrial (PEPCK-m). The protein content and enzyme activity of G6PC were also significantly higher (P < 0.05) in FTO+ cells. Moreover, CCAAT/enhancer-binding protein-beta (C/EBP-beta) and cAMP responsive element binding protein 1 (CREB1), which were found to transcriptionally regulate the expression of G6PC, were increased at the level of both mRNA (P < 0.05) and protein (P < 0.05) in FTO+ cells. ChIP analysis revealed significantly higher (P < 0.05) binding of C/EBP-beta and phospho-CREB1 to G6PC gene promoter in FTO+ cells. In addition, the interaction of FTO and C/EBP-beta was significantly enhanced (P < 0.05) in FTO+ cells. Opposite changes in G6PC expression and regulation were observed in FTO− cells. Our results indicate that chicken FTO regulates gluconeogenesis in DF-1 cells through enhanced transcriptional regulation of G6PC gene by C/EBP-beta and phospho-CREB1.