Cloning, expression and glucose regulation activity of human FGF-21

Fibroblast growth factor (FGF)-21 is a recently discovered glucose regulator and has potential to become therapeutics for treatment of type 2 diabetes. The aim of this study was to clone and express human FGF-21 gene and characterize its bioactivity for glucose regulation. The hFGF-21 cDNA was cloned from human liver by RT-PCR and subcloned into the pSUMO vector after sequencing confirmation. The recombinant plasmid was transformed into Escherichia coli Rosetta strain. The FGF-21 protein expression was induced by IPTG and purified by Ni-NTA agarose. The FGF-21 product was verified by Western blotting analysis with specific antibody. The bioactivity of the purified protein was examined by glucose uptake assay in 3T3-L1 adipocytes. The cloned hFGF-21 gene consisted of 546 bp, which was in agreement with the published data in GenBank. SDS-PAGE analysis showed that hFGF-21 expressed in the E. coli system was 19.4 kDa in size. The glucose uptake assay in 3T3-L1 adipocytes indicated that the purified hFGF-21 could stimulate glucose uptake in a dose-dependent manner, and glucose transporters (GLUT1) is the functional unit.