Cloning of human growth factor Activin A and the effects of cytoplasmic chaperons co-expression with it

Activin A, a member of the transforming growth factor-β (TGF-β) superfamily, plays a central role in numerous physiological processes such as cell differentiation, tissue repair, angiogenesis, differentiation of stem cells, cell adhesion and apoptosis. Because of its various clinical usages, recombinant production of it is beneficial. Since E. coli is one of the most popular hosts for recombinant protein production, in this study, cytoplasmic expression in this strain was used to produce high levels of Activin A. So, the cDNA of the Activin A mature region was amplified and then cloned in pET28a(+) vector. The resulting vector was transformed to BL21(DE3), BL21(DE3)plysS, and BL21(DE3)Rosetta-gami strains. After induction the promoter by using IPTG, Activin A production was confirmed by SDS-PAGE and Western blotting assays. The results showed that the expression of Activin A in the cytoplasm of all three strains was an efficient approach to obtain high levels of recombinant protein, but BL21(DE3) strain produced more protein. At the next step in order to achieve soluble form of Activin A, co-expression of cytoplasmic chaperones TF, GroEL/ES, and DnaK with pET28a (+) vector was used. The SDS-PAGE and Western blotting results showed that co-expression of Activin A with cytoplasmic plasmid pGro7 containing GroEL and GroES chaperones, in BL21(DE3) strain is an efficient approach for producing of soluble Activin A.