Expression and identification of recombinant human interleukin 7 product in Escherichia coli

Aim:To construct a prokaryotic expression vector for human interleukin7(IL-7),identify its expression product and optimize its expression condition. Methods: The cDNA fragment encoding human IL-7 was amplified by RT-PCR from the total RNA of human PBMC,and then the IL-7 gene was cloned into pET-3d plasmid to construct a prokaryotic expression vector.The positive clone was analyzed by DNA sequencing.The recombinant protein was expressed in Escherichia coli(E.coli) BL21(DE3) strain and identified with Western blotting.Results: The prokaryotic expression vector forIL-7 was constructed and confirmed by sequencing.The expression vector was transformed into E.coli and was expressed in after induction with IPTG.The relative molecular weight of the protein was 17 400,which is consistent with theoretical value.Western blotting showed that the recombinant protein was mainly presented in inclusion bodies.The optimized expression condition was 4 h induction at 37 ℃ with 0.4 mmol/L IPTG.Conclusion:The prokaryotic expression vector for human IL-7 has been constructed successfully and the expression condition has been optimized,which has paved the way for further study on human IL-7.