title: MT1-MMP releases latent TGF-beta1 from endothelial cell extracellular matrix via proteolytic processing of LTBP-1.
abstract: Targeting of transforming growth factor beta (TGF-beta) to the extracellular matrix (ECM) by latent TGF-beta binding proteins (LTBPs) regulates the availability of TGF-beta for interactions with endothelial cells during their quiescence and activation. However, the mechanisms which release TGF-beta complexes from the ECM need elucidation. We find here that morphological activation of endothelial cells by phorbol 12-myristate 13-acetate (PMA) resulted in membrane-type 1 matrix metalloproteinase (MT1-MMP) -mediated solubilization of latent TGF-beta complexes from the ECM by proteolytic processing of LTBP-1. These processes required the activities of PKC and ERK1/2 signaling pathways and were coupled with markedly increased MT1-MMP expression. The functional role of MT1-MMP in LTBP-1 release was demonstrated by gene silencing using lentiviral short-hairpin RNA as well as by the inhibition with tissue inhibitors of metalloproteinases, TIMP-2 and TIMP-3. Negligible effects of TIMP-1 and uPA/plasmin system inhibitors indicated that secreted MMPs or uPA/plasmin system did not contribute to the release of LTBP-1. Current results identify MT1-MMP-mediated proteolytic processing of ECM-bound LTBP-1 as a mechanism to release latent TGF-beta from the subendothelial matrix.
authors.affiliation: Departments of Pathology and Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland.
authors.forename: Olga
authors.initials: O
authors.lastname: Tatti
authors.forename: Piia
authors.initials: P
authors.lastname: Vehviläinen
authors.forename: Kaisa
authors.initials: K
authors.lastname: Lehti
authors.forename: Jorma
authors.initials: J
authors.lastname: Keski-Oja
mesh_terms: D048430:Cell Shape / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D053779:Latent TGF-beta Binding Proteins / Q000378:metabolism*; D053511:Matrix Metalloproteinase 14 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D061965:Matrix Metalloproteinase Inhibitors; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
chemical_list: C509032:LTBP1 protein, human; D053779:Latent TGF-beta Binding Proteins; D061965:Matrix Metalloproteinase Inhibitors; D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D053511:Matrix Metalloproteinase 14