title: Type I collagen abrogates the clathrin-mediated internalization of membrane type 1 matrix metalloproteinase (MT1-MMP) via the MT1-MMP hemopexin domain.
abstract: Type I collagen (Col I)-stimulated matrix metalloproteinase-2 (MMP-2) activation via membrane type 1 MMP (MT1-MMP) involves both a transcriptional increase in MT1-MMP expression and a nontranscriptional response mediated by preexisting MT1-MMP. In order to identify which MT1-MMP domains were required for the nontranscriptional response, MCF-7 cells that lack endogenous MT1-MMP were transfected with either wild type or domain mutant MT1-MMP constructs. We observed that mutant constructs lacking the MT1-MMP cytoplasmic tail were able to activate MMP-2 in response to Col I but not a construct lacking the MT1-MMP hemopexin domain. Col I did not alter total MT1-MMP protein levels; nor did it appear to directly induce MT1-MMP oligomerization. Col I did, however, redistribute preexisting MT1-MMP to the cell periphery compared with unstimulated cells that displayed a more diffuse staining pattern. In addition, Col I blocked the internalization of MT1-MMP in a dynamin-dependent manner via clathrin-coated pit-mediated endocytosis. This mechanism of impaired internalization is different from that reported for concanavalin A, since it is not mediated by the cytoplasmic tail of MT1-MMP but rather by the hemopexin domain. In summary, upon Col I binding to its cell surface receptor, MT1-MMP internalization via clathrin-coated pit-mediated endocytosis is impaired through interactions with the hemopexin domain, thereby regulating its function and ability to activate MMP-2.
authors.affiliation: VBCRC Invasion and Metastasis Group, St. Vincent's Institute, Fitzroy, Victoria 3065, Australia.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Lafleur
authors.forename: Francesca A
authors.initials: FA
authors.lastname: Mercuri
authors.forename: Neeracha
authors.initials: N
authors.lastname: Ruangpanit
authors.forename: Motoharu
authors.initials: M
authors.lastname: Seiki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
authors.forename: Erik W
authors.initials: EW
authors.lastname: Thompson
mesh_terms: D045744:Cell Line, Tumor; D002966:Clathrin / Q000502:physiology*; D024042:Collagen Type I / Q000502:physiology*; D003208:Concanavalin A / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology; D006466:Hemopexin / Q000235:genetics; D006801:Humans; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002966:Clathrin; D024042:Collagen Type I; D011993:Recombinant Fusion Proteins; D003208:Concanavalin A; D006466:Hemopexin; D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1