Ingvarsen Signe, Madsen Daniel H, Hillig Thore, Lund Leif R, Holmbeck Kenn, Behrendt Niels, Engelholm Lars H
The Finsen Laboratory Department 3735, Rigshospitalet, Ole Maaløes Vej 5, Copenhagen N, Denmark.
Biol Chem. 2008 Jul;389(7):943-53. doi: 10.1515/BC.2008.097.
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.
分泌型明胶酶基质金属蛋白酶-2（MMP-2）和膜锚定基质金属蛋白酶MT1-MMP（MMP-14）是细胞外基质降解中细胞周围蛋白水解的核心参与者。除了具有直接的胶原分解和明胶分解活性外，这些酶还参与了一个级联途径，其中MT1-MMP激活MMP-2前酶。该反应与基质金属蛋白酶抑制剂TIMP-2相互作用发生，提出的机制涉及两个MT1-MMP分子与一个TIMP-2分子形成复合物。我们提供了确凿的证据，表明前MMP-2的激活受成纤维细胞和纤维肉瘤细胞表面MT1-MMP二聚化的调控。即使在没有转染和过表达的情况下，MT1-MMP的二聚化也显著刺激了活性MMP-2产物的形成。此处所示的效应是由一种单克隆抗体引起的，免疫荧光实验表明该抗体特异性结合MT1-MMP。该抗体对催化活性没有影响。对前MMP-2激活的影响涉及MT1-MMP二聚化，因为它需要二价单克隆抗体，单价Fab片段则没有效果。由于在没有二聚化的情况下，表达MT1-MMP的细胞仅获得可忽略不计水平的前MMP-2激活，我们的结果将二聚化事件确定为蛋白水解级联调节的关键水平。
