An efficient method for bacterial production and activity assessment of recombinant human insulin like growth factor 1

Human insulin like growth factor 1 directs physiological roles in cellular proliferation and differentiation process. The protein is considered as an important therapeutic target with clinical significance. In this study, to avoid production of human insulin like growth factor 1 as inclusion body, the thioredoxin was used as a solubilizing fusion tag. The expression of fusion human insulin like growth factor 1 was carried out in E. coli Rosetta-gami by transformation of pET-32b contained functional elements. The evaluation of different conditions involving protein expression including IPTG concentration, temperature and post induction time showed that 0.1 mM IPTG at 34 °C for 4 h was the optimum condition. The isolated fusion protein was purified using nickel affinity purification and digested by entrokinase to produce mature recombinant protein without any additional tag. The accuracy of produced recombinant protein was confirmed by western blot analysis. Biological activity of produced recombinant human insulin like growth factor 1 was determined by its proliferation effects on MCF-7 cells, expansion of bovine granulosa cells and activation of PI3K/Akt signaling pathway in these cells. The present study provides a simple and efficient method for high-level production of soluble, active recombinant human insulin like growth factor 1 in E. coli.