Expression of mutated insulin gene in HepG-2 cell line / 解放军医学杂志

ABSTRACT

Objective To express a mutated insulin gene in HepG-2 cell line to further research of insulin gene therapy. Methods Native human insulin cDNA was obtained from fetus pancreas with RT-PCR. Furin consensus cleavage sequence was introduced into proinsulin cDNA with site-directed mutagenesis (overlap extension PCR), and the new sequence was named as INS/furin. Subsequently, INS/furin was subcloned into the multiple clone sites of plasmid p(G1RE)3BP-1Luc. The new plasmid p(G1RE)3BP-11?furin was identified with the method of enzyme digestion by Hind Ⅲ and EcoR V. HepG-2 cells were transfected with the plasmid p(G1RE)3BP-11?furin by liposome-mediated method. The transfected HepG-2 cells were incubated for 48h in a glucose-containing medium (25mmol/L), and then the conditioned media were collected and HepG-2 cells were harvested respectively. The expression of INS/furin mRNA in transfected HepG-2 cells was examined by RT-PCR, the regained DNA was sequenced and insulin in conditioned media was investigated by radioimmunoassay. Results Two enzymes, Hind Ⅲ and EcoR V, digested p(G1RE)3BP-11?furin, and 2 fragments with length of 260 bp and 4 700bp, were obtained. The 260bp fragment was identified as insulin/furin, indicating that the target gene had been successfully inserted in specific sites. RT-PCR showed that insulin/furin mRNA was expressed in transfected HepG-2 cell, and the regained DNA was confirmed as insulin/furin by sequencing; while insulin was detected by radioimmunoassay in conditioned media. Conclusion The recombinant mammalian expression plasmid p(G1RE)3BP-11?furin has been successfully constructed, and transfected into HepG-2 cells, which therefore may efficiently secrete bioactive insulin.