title: The inactive 44-kDa processed form of membrane type 1 matrix metalloproteinase (MT1-MMP) enhances proteolytic activity via regulation of endocytosis of active MT1-MMP.
abstract: Membrane type 1 (MT1) matrix metalloproteinase (MMP-14) is a membrane-tethered MMP considered to be a major mediator of pericellular proteolysis. MT1-MMP is regulated by a complex array of mechanisms, including processing and endocytosis that determine the pool of active proteases on the plasma membrane. Autocatalytic processing of active MT1-MMP generates an inactive membrane-tethered 44-kDa product (44-MT1) lacking the catalytic domain. This form preserves all other enzyme domains and is retained at the cell surface. Paradoxically, accumulation of the 44-kDa form has been associated with increased enzymatic activity. Here we report that expression of a recombinant 44-MT1 (Gly(285)-Val(582)) in HT1080 fibrosarcoma cells results in enhanced pro-MMP-2 activation, proliferation within a three-dimensional collagen I matrix, and tumor growth and lung metastasis in mice. Stimulation of pro-MMP-2 activation and growth in collagen I was also observed in other cell systems. Expression of 44-MT1 in HT1080 cells is associated with a delay in the rate of active MT1-MMP endocytosis resulting in higher levels of active enzyme at the cell surface. Consistently, deletion of the cytosolic domain obliterates the stimulatory effects of 44-MT1 on MT1-MMP activity. In contrast, deletion of the hinge turns the 44-MT1 form into a negative regulator of enzyme function in vitro and in vivo, suggesting a key role for the hinge region in the functional relationship between active and processed MT1-MMP. Together, these results suggest a novel role for the 44-kDa form of MT1-MMP generated during autocatalytic processing in maintaining the pool of active enzyme at the cell surface.
authors.affiliation: Department of Pathology and Proteases and Cancer Program, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, Michigan 48201, USA.
authors.forename: Jin-Ah
authors.initials: JA
authors.lastname: Cho
authors.forename: Pamela
authors.initials: P
authors.lastname: Osenkowski
authors.forename: Huiren
authors.initials: H
authors.lastname: Zhao
authors.forename: Seaho
authors.initials: S
authors.lastname: Kim
authors.forename: Marta
authors.initials: M
authors.lastname: Toth
authors.forename: Kristina
authors.initials: K
authors.lastname: Cole
authors.forename: Amro
authors.initials: A
authors.lastname: Aboukameel
authors.forename: Allen
authors.initials: A
authors.lastname: Saliganan
authors.forename: Lucia
authors.initials: L
authors.lastname: Schuger
authors.forename: R Daniel
authors.initials: RD
authors.lastname: Bonfil
authors.forename: Rafael
authors.initials: R
authors.lastname: Fridman
mesh_terms: D000818:Animals; D002384:Catalysis; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D003094:Collagen / Q000737:chemistry; D003600:Cytosol / Q000378:metabolism; D004705:Endocytosis; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D000882:Haplorhini; D006801:Humans; D053511:Matrix Metalloproteinase 14 / Q000502:physiology*; D008954:Models, Biological; D009362:Neoplasm Metastasis; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D011994:Recombinant Proteins; D003094:Collagen; D053511:Matrix Metalloproteinase 14