Recombinant Expression and Bioactivity Characterization of TAT-Fused Thymosin β10

Thymosin beta 10 (TB10) is one of the common members among beta-thymosins. Human TB10 is reported to play a role in anti-angiogenesis and inhibition of cell migration during the tumorigenesis or metastasis of some certain cancers. Thus, it would be a potent clinical agent. In the present study, the coding sequence of TB10 was optimized based on the codon preference of Escherichia coli and cloned to pET28a (+) by chemical synthesis and molecular cloning methods. The recombinant protein was highly expressed employing E. coli expressing system and purified by a simple step of Ni²⁺ affinity chromatography. The TEV proteinase recognition site was inserted in the His₆-tag and the target protein for easy removal of the His₆-tag. To improve the biological activity of TB10, the transactivator of transcription (TAT) short peptide, a transduction domain, was added to the N-terminus of TB10. About 14.3 mg of the recombinant TB10 proteins was obtained from 1 L bacterial culture. The functional analyses demonstrated that the recombinant TB10 proteins displayed the distinct inhibition on angiogenesis by chick embryo chorioallantoic membrane assay and endothelial cell migration by wound healing assay. The TAT-fused TB10 even had stronger effects, probably due to the better transduction into the cells.