Screening of TACE peptide inhibitors from phage display peptide library.

To obtain the recombinant tumor necrosis factor-alpha converting enzyme (TACE) ectodomain and use it as a selective molecule for the screening of TACE peptide inhibitors, the cDNA coding catalytic domain (T800) and full-length ectodomain (T1300) of TACE were amplified by RT-PCR, and the expression plasmids were constructed by inserting T800 and T1300 into plasmid pET-28a and pET-28c respectively. The recombinant T800 and T1300 were induced by IPTG, and SDS-PAGE and Western blotting analysis results revealed that T800 and T1300 were highly expressed in the form of inclusion body. After Ni(2+)-NTA resin affinity chromatography, the recombinant proteins were used in the screening of TACE-binding peptides from phage display peptide library respectively. After 4 rounds of biopanning, the positive phage clones were analyzed by ELISA, competitive inhibition assay and DNA sequencing. A common amino acid sequence (TRWLVYFSRPYLVAT) was found and synthesized. The synthetic peptide could inhibit the TNF-alpha release from LPS-stimulated human peripheral blood mononuclear cells (PBMC) up to 60.3%. FACS analysis revealed that the peptide mediated the accumulation of TNF-alpha on the cell surface. These results demonstrate that the TACE-binding peptide is an effective antagonist of TACE.