Regulation of the autoactivation of human 72-kDa progelatinase by tissue inhibitor of metalloproteinases-2

Membrane proteases: roles in tissue remodeling and tumour invasion

The coordinated control of extracellular matrix degradation on the cell surface involves three crucial elements: secreted proteases and their inhibitors, surface protease receptors and integral membrane proteases. The roles that each of these elements play in cell surface proteolysis are described. The localization of proteases to the cell surface, protease activation, and regulation of cell surface proteolysis by protease inhibitors are key issues for elucidating the role of membrane proteases in tissue remodeling and tumour invasion.

The matrix-degrading metalloproteinases

The matrix-degrading metalloproteinases are an intriguing family of enzymes that have evolved to digest specific extracellular matrix components. The expression of these enzymes is very highly regulated and can be controlled transcriptionally by a number of growth factors, tumor promoters, oncogenes, and hormones. It is suggested that the coordinated regulation of matrix metalloproteinases and their inhibitors by these agents modify the integrity of the extracellular matrix. These modifications may, at least in part, be responsible for mediating the effects of these factors on complex physiological processes.

Activation of TIMP-2/progelatinase A complex by stromelysin

Progelatinase A was purified as a complex with TIMP-2 from the conditioned medium of a human glioblastoma cell line. The TIMP-2/progelatinase complex was resistant to the activation by p-aminophenylmercuric acetic acid (APMA), and showed less than 10% of the activity of the TIMP-2-free active enzyme. When the complex was incubated with stromelysin in the presence of APMA, the 64-kDa progelatinase was effectively converted to the 57-kDa mature enzyme, increasing its gelatinolytic activity about 8-fold. These results suggest that stromelysin is a natural activator of TIMP-2-bound progelatinase A.

Growth-promoting activity of tissue inhibitor of metalloproteinases-1 (TIMP-1) for a wide range of cells. A possible new growth factor in serum

Human tissue inhibitor of metalloproteinases-1 (TIMP-1), but not TIMP-2, has potent growth-promoting activity for a wide range of human and bovine cells. TIMP-1 seems to be a new cell-growth factor in serum and to stimulate the cells independently of its inhibitory activity.

Isolation and characterization of tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) from human rheumatoid synovial fluid

The tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2 were purified to apparent homogeneity from human rheumatoid synovial fluid (HRSF). The inhibitors were isolated by dissociation of non-covalent gelatinase/TIMP complexes. TIMP-1 migrated as a single polypeptide with Mr 28,500 on SDS-PAGE, while the Mr of TIMP-2 was 21,000. The inhibitory activity was stable under heat and acid pH. N-terminal sequence data were obtained for the first 15 residues of both inhibitors and showed identity to the human fibroblast inhibitors TIMP-1 and TIMP-2. This is the first demonstration that TIMP-1 and TIMP-2 can be directly purified from human rheumatoid synovial fluid. The complex formation between the metalloproteinase inhibitors and leucocyte metalloproteinases was shown by immunoblotting.

The matrix metalloproteinases and their natural inhibitors: prospects for treating degenerative tissue diseases

Uncontrolled matrix metalloproteinase activity is thought to be a cause of the tissue damage observed in many disease processes. None of the drugs currently in use can prevent tissue destruction, and strategies for the development of synthetic inhibitors have been hampered by a poor understanding of the biochemistry of matrix metalloproteinases. Recent cDNA cloning efforts and characterization of recombinant human matrix metalloproteinases have permitted structure-function analysis of the enzymes and their inhibitors. Progress in this area should help indicate a route to rational strategies for designing lead therapeutic compounds.

Characterization of metalloproteinases and tissue inhibitors of metalloproteinases in human plasma

In this study, we have identified and characterized metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs) in human plasma. Treatment of plasma with trypsin or aminophenylmercuric acetate resulted in activation of latent gelatinolytic activity. Fractionation of plasma by gelatin Sepharose chromatography resulted in the isolation of 72 kDa and 92 kDa gelatinases/type IV collagenases. The 72 kDa gelatinase was purified by gel filtration chromatography. Stromelysin-1 was isolated from plasma by Matrex green A affinity chromatography. Immunoblotting of plasma fractions with antibodies to unique peptide regions of human gelatinases differentiated the 72 kDa gelatinase from the 92 kDa gelatinase. Antibodies to the amino terminal peptides of each enzyme were used to determine that plasma gelatinases circulate as latent proenzymes. Immunoblotting with antibodies directed against human stromelysin identified a 57 kDa stromelysin. TIMP-1 (28 kDa) and TIMP-2 (21 kDa) were also identified by immunoblotting of gelatin Sepharose bound plasma proteins using non-crossreacting antibodies to each protein.

Immunoassay of type IV collagenase / gelatinase (MMP-2) in human plasma

We have developed a sensitive and specific sandwich type enzyme-linked immunosorbent assay (ELISA) to detect type IV collagenase (MMP-2) in human plasma which employs the combination of affinity purified rabbit polyclonal antibodies and mouse monoclonal antibodies to human MMP-2. The MMP-2 ELISA detects latent and activated MMP-2, MMP-2 complexed with TIMP and MMP-2 complexed with alpha 2 macroglobulin (65% efficiency). To determine whether physiologic conditions associated with increased connective tissue turnover are accompanied by increased MMP-2 levels in plasma, we compared enzyme levels in pregnant and nonpregnant women. Plasma MMP-2 (mean +/- standard deviation) was significantly increased (p less than 0.05) in the second half of pregnancy (650 +/- 312) as compared to early pregnancy (356 +/- 139) or the nonpregnant state (387 +/- 193). As a result of the linkage between type IV collagenase production by cancer cells and the metastatic phenotype, the assay of MMP-2 in plasma is of potential clinical value in cancer.