An fgf21-like gene from swamp eel (Monopterus albus): Recombinant expression and its potential roles in glucose and lipid homeostasis

Abstract

Fibroblast growth factor 21 (FGF21) plays important roles in the regulation of glucose and lipid metabolism and energy balance in mammals. In this study, the full-length cDNA of swamp eel fgf21 was cloned. Sequence analysis showed that swamp eel FGF21 displayed high similarity with FGF21 of other vertebrates. Subsequently, a prokaryotic expression vector for swamp eel fgf21 was constructed, and recombinant FGF21 (rFGF21) was successfully induced and purified. To investigate the potential roles of swamp eel FGF21 in glucose and lipid metabolism, we examined the effects of rFGF21 on regulation of glucose and lipid homeostasis in type 1 diabetes mellitus (T1DM) mice as well as swamp eels under glucose stress. In T1DM mice, the levels of blood glucose, serum triglyceride (TG), liver TG, serum total cholesterol (TC), and liver TC were significantly downregulated after repeated daily injection of rFGF21 for 15 days. In addition, liver pathological section analysis indicated that rFGF21 alleviated the degree of damage to liver cells in T1DM mice. Furthermore, rFGF21 significantly upregulated the mRNA expression levels of peroxisome proliferators-activated receptor alpha (Pparα), β-Klotho, fibroblast growth factor receptor 1 (Fgfr1), phosphoenolpyruvate carboxykinase (Pepck), glucose transporter 1 (Glut1), and glucose transporter 4 (Glut4) in T1DM mouse livers. Moreover, in swamp eels, rFGF21 significantly decreased blood glucose and liver TC levels under glucose stress and upregulated the mRNA expression levels of fgf21, pparα, β-klotho, and fgfr1 in liver tissue. These results suggested that FGF21 plays important roles in the regulation of glucose and lipid homeostasis in swamp eel.