Production of Soluble Murine TRAILs in Escherichia coli with Zn2+ Supplementation

Abstract

Background: Accumulating evidence has demonstrated the immunomodulatory effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in rheumatoid arthritis and the tumor microenvironment, besides its known capacity of specifically inducing the apoptosis of cancer cells. Mice are common available animal models for studying the roles of TRAIL. However, mice express only a single TRAIL receptor (mTRAILR) with an intracellular death domain, in contrast to the two TRAIL receptors (TRAILR1 and TRAILR2) in humans. Moreover, human TRAIL binds weakly to mTRAILR, whereas mouse TRAIL has high affinity for the human TRAIL-Rs. Therefore, we considered that murine TRAIL would be more suitable than human TRAIL for exploring the immunoregulatory effect of TRAIL in immunocompetent mice or when using mouse cells as the target. To our knowledge, the detailed method for production of recombinant murine TRAIL has not been reported. Objective: In this study, we aimed to design and express two soluble forms of murine TRAIL and verify the properties of the protein. Methods: Recombinant murine TRAILs were expressed in Escherichia coli BL21 (DE3, and Ni-chelating affinity chromatography was used for protein purification. SDS-PAGE, GDS-PAGE and HPLC were applied to analyze the protein structure. The cytotoxicity of our purified murine TRAILs was evaluated in the TRAIL-sensitive human breast cancer ZR-75-30 cells and murine breast cancer 4T1 cells. Finally, validation of the tumor-killing ability of the murine protein in vivo. Results: Two soluble forms of murine TRAILs (mT_N99 and mT_N188) were purified and demonstrated with high purity and trimeric structure. In addition, Zn2+ supplement was essential to produce soluble murine TRAILs in E.coli BL21 (DE3). The two purified soluble mTRAILs showed similar cytotoxicity to cancer cells, moreover, mT_N99 also showed a good anti-tumor effect in vivo and is more suitable for the treatment of murine tumor models. Conclusion: A production approach for recombinant murine TRAIL was determined, which covered the design of shortened forms, expression, purification and characterization.