Invitro reconstitution of complexes between pro-matrix metalloproteinase-9 and the proteoglycans serglycin and versican

Previously, we have shown that a proportion of the matrix metalloproteinase-9 (MMP-9) synthesized by the macrophage cell line THP-1 binds to a chondroitin sulfate proteoglycan (CSPG) core protein to form a reduction-sensitive heteromer. It was also shown that the hemopexin-like (PEX) domain and the fibronectin-like (FnII) module in the enzyme are involved in heteromer formation. In this paper, we show that reduction-sensitive and SDS-stable heteromers may be reconstituted invitro by mixing proMMP-9 with either serglycin, versican or CSPGs isolated from various monocytic cell lines. In addition, a strong but SDS-soluble proMMP-9CSPG heteromer was formed. The two macromolecules in the SDS-stable reduction-sensitive heteromers were not linked together by disulfide bonds. As for the heteromer isolated from THP-1 cells, invitro reconstituted SDS-stable and SDS-soluble heteromers showed weaker binding to gelatin than the proMMP-9 monomer. Furthermore, gelatin inhibited invitro reconstitution of the heteromers, showing that the FnII module is involved in the complex formation. Tissue inhibitor of metalloproteinase (TIMP)-1was not be detected in the proMMP-9CSPG complexes. However, the presence of TIMP-1 inhibited formation of the SDS-soluble heteromer, but not the SDS-stable reduction-sensitive heteromer. This indicates that different regions in the PEX domain are involved formation of these heteromers. Structured digital abstract proMMP-9 and proMMP-9 bind by comigration in gel electrophoresis (View interaction) proMMP-9 and proMMP-9 bind by zymography (View interaction)