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Homophilic complex formation is prerequisite for MT1‐MMP to degrade type‐I collagen on the cell surface
Author(s) -
Itoh Yoshifumi,
Ito Noriko,
Nagase Hideaki,
Seiki Motoharu
Publication year - 2004
Publication title -
international journal of experimental pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.671
H-Index - 72
eISSN - 1365-2613
pISSN - 0959-9673
DOI - 10.1111/j.0959-9673.2004.369bd.x
Subject(s) - matrix metalloproteinase , microbiology and biotechnology , chemistry , collagenase , zymogen , cd44 , extracellular matrix , collagen, type i, alpha 1 , transfection , type i collagen , mutant , cell , biochemistry , biology , gene , enzyme , endocrinology
MT1‐MMP degrades a wide variety of extra‐cellular matrix macromolecules and some cell‐surface proteins such as CD44, transglutaminase and α v ‐integrin, and activates zymogen of MMP‐2 and MMP‐13. Among these activities, the collagenolytic activity is one of the most important functions of the enzyme in biology, as the phenotypes of MT1‐MMP gene knockout mice, such as abnormal skeletal development and various connective tissue abnormalities, are thought to be attributed to the lack of cellular collagenase activity. We have previously shown that MT1‐MMP forms homophilic complex through its haemopexin (HPX) domain facilitating the activation of proMMP‐2 (Itoh et al . 2001). In this report, we present data that collagen‐degrading activity of MT1‐MMP also requires homophilic complex formation. Methods COS7 cells were cultured on type‐I collagen film and transfected with MT1‐MMP and its mutant gene to look at collagen degradation activity of these gene products. Results Co‐expression of the catalytic domain‐deleted mutant of MT1‐MMP (MT1δCat) with the wild‐type enzyme inhibited its homophilic complex formation as well as its ability to activate proMMP‐2 on the cell surface, and MT1δCat also inhibited cell‐surface collagenolytic activity of the wild‐type MT1‐MMP. A chimeric MT1‐MMP mutant (MT‐MMP13) whose catalytic domain, hinge region and HPX domain were replaced with those derived from collagenase‐3 (MMP‐13) did not degrade collagen though MT‐MMP13 was expressed and maintained its proteolytic activity against gelatin on the cell surface. When an interface for homophilic complex formation, the HPX domain derived from MT1‐MMP, was further added to the chimeric enzyme (MT‐MMP13‐HPX mt1 ), it degraded collagen. Co‐expression of MT1dCat and MT‐MMP13‐HPX mt1 also inhibited the collagenolytic activity. Discussion Homphilic complex formation is prerequisite for the expression of collagenase activity on the cell surface. Presumably, each MT1‐MMP in the complex has different roles; one unwinds triple‐helical structure of collagen locally and the other cuts peptide bond.