Dimerization of endogenous MT1-MMP is a regulatory step in the activation of the 72-kDa gelatinase MMP-2 on fibroblasts and fibrosarcoma cells.
The secreted gelatinase matrix metalloprotease-2 (MMP-2) and the membrane-anchored matrix metalloprotease MT1-MMP (MMP-14), are central players in pericellular proteolysis in extracellular matrix degradation. In addition to possessing a direct collagenolytic and gelatinolytic activity, these enzymes take part in a cascade pathway in which MT1-MMP activates the MMP-2 proenzyme. This reaction occurs in an interplay with the matrix metalloprotease inhibitor, TIMP-2, and the proposed mechanism involves two molecules of MT1-MMP in complex with one TIMP-2 molecule. We provide positive evidence that proMMP-2 activation is governed by dimerization of MT1-MMP on the surface of fibroblasts and fibrosarcoma cells. Even in the absence of transfection and overexpression, dimerization of MT1-MMP markedly stimulated the formation of active MMP-2 products. The effect demonstrated here was brought about by a monoclonal antibody that binds specifically to MT1-MMP as shown by immunofluorescence experiments. The antibody has no effect on the catalytic activity. The effect on proMMP-2 activation involves MT1-MMP dimerization because it requires the divalent monoclonal antibody, with no effect obtained with monovalent Fab fragments. Since only a negligible level of proMMP-2 activation was obtained with MT1-MMP-expressing cells in the absence of dimerization, our results identify the dimerization event as a critical level of proteolytic cascade regulation.
Ingvarsen
Signe
S
The Finsen Laboratory Department 3735, Rigshospitalet, Ole Maaløes Vej 5, Copenhagen N, Denmark.
Madsen
Daniel H
DH
Hillig
Thore
T
Lund
Leif R
LR
Holmbeck
Kenn
K
Behrendt
Niels
N
Engelholm
Lars H
LH
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002417:Cattle; D045744:Cell Line, Tumor; D019281:Dimerization; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D006466:Hemopexin / Q000378:metabolism; D006801:Humans; D007114:Immunization; D053511:Matrix Metalloproteinase 14 / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
D000911:Antibodies, Monoclonal; D004792:Enzyme Precursors; C507096:Mmp14 protein, mouse; D006466:Hemopexin; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14