title: Regulation of membrane-type 1 matrix metalloproteinase activity by vacuolar H+-ATPases.
abstract: Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a key enzyme in normal development and malignant processes. The regulation of MT1-MMP activity on the cell surface is a complex process involving autocatalytic processing, tissue inhibitor of MMPs (TIMP) binding and constitutive internalization. However, the fate of internalized MT1-MMP is not known. Acidification of intracellular vacuolar compartments is essential for membrane trafficking, protein sorting and degradation. This acidification is controlled by vacuolar H(+)-ATPases, which can be selectively inhibited by bafilomycin-A(1). Here, we treated human tumour cell lines expressing MT1-MMP with bafilomycin-A(1), and analysed its effects on MT1-MMP activity, internalization and processing. We show that the activity of MT1-MMP on the cell surface is constitutively down-regulated through a vacuolar H(+)-ATPase-dependent degradation process. Blockade of this degradation caused the accumulation of TIMP-free active MT1-MMP molecules on the cell surface, although internalization was not affected. As a consequence of this impaired degradation, pro-MMP-2 activation was strongly enhanced. This study demonstrates that the catalytic activity of MT1-MMP on the cell surface is regulated through a vacuolar H(+)-ATPase-dependent degradation process.
authors.affiliation: Laboratory of Tumor and Development Biology, University of Liège, Tour de Pathologie (B23), Sart Tilman, B-4000 Liège, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Maquoi
authors.forename: Karine
authors.initials: K
authors.lastname: Peyrollier
authors.forename: Agnès
authors.initials: A
authors.lastname: Noël
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Foidart
authors.forename: Francis
authors.initials: F
authors.lastname: Frankenne
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D018942:Macrolides; D020781:Matrix Metalloproteinase 1 / Q000235:genetics* / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D008545:Melanoma; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D018942:Macrolides; D011994:Recombinant Proteins; D019716:Tissue Inhibitor of Metalloproteinase-2; C040929:bafilomycin A1; D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1; D025262:Vacuolar Proton-Translocating ATPases