title: The alpha 2 chain of collagen type VI sequesters latent proforms of matrix-metalloproteinases and modulates their activation and activity.
abstract: The extracellular matrix (ECM) attracts increasing attention as a store of biologically active molecules and as a reservoir of potent cell signalling molecules released by proteolytic action. Both, cytokines and proteases mediating such release are sequestered in the ECM. Here, we found matrix metalloproteinase (MMP) proforms closely associated with collagenous septae in fibrotic liver tissue, and we screened immobilized human placenta-derived collagen chains and other ECM proteins for MMP-binding activity. Following the establishment of a novel highly-efficient two-step chromatography procedure for the isolation of the purified alpha-chains of the pepsin-resistant triple-helical CVI fragment (CVI/PR) solid phase and surface plasmon resonance binding studies were performed. We identified the triple-helical domain of the alpha2 chain of microfilamentous CVI alpha2(VI) as having nanomolar affinity for the collagenases proMMP-1, -8 , -13 and stromelysin-1 (MMP-3), thus extending the repertoire of pericellular and substrate-based interactions of MMPs. Enzymatic activity assays enabled the correlation of MMP activity with CVI binding, in that alpha2(VI) chain-mediated inhibition of enzymatic activity is accompanied by increased binding. Similar results were shown for the gelatinase proMMP-9, whereas for proMMP-2, the alpha2(VI) chain at low concentrations seems to interfere with prodomain binding resulting in enhanced activity without scission of the prodomain. Stable complexes of proMMP-2 and alpha2(VI) chain competed with gelatinase binding to the preferred ligand, collagen type I. In conclusion, the alpha2(VI) chain modulates MMP availability by sequestering proMMPs in the ECM, blocking proteolytic activity. Therefore, CVI and especially its alpha2(VI) chain might serve as a lead structure for MMP-based therapeutics which modulates the action of these matrix components, e.g. in fibrosis and cancer.
authors.affiliation: Department of Gastroenterology and Hepatology, Charité, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Freise
authors.forename: Ulrike
authors.initials: U
authors.lastname: Erben
authors.forename: Marion
authors.initials: M
authors.lastname: Muche
authors.forename: Richard
authors.initials: R
authors.lastname: Farndale
authors.forename: Martin
authors.initials: M
authors.lastname: Zeitz
authors.forename: Rajan
authors.initials: R
authors.lastname: Somasundaram
authors.forename: Martin
authors.initials: M
authors.lastname: Ruehl
mesh_terms: D001667:Binding, Competitive / Q000502:physiology; D055162:Biocatalysis / Q000187:drug effects; D002853:Chromatography, Liquid / Q000379:methods; D003094:Collagen / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D024142:Collagen Type VI / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D006801:Humans; D008099:Liver / Q000378:metabolism; D008103:Liver Cirrhosis / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020784:Matrix Metalloproteinase 8 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D053505:Matrix Metalloproteinases, Secreted / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010920:Placenta / Q000737:chemistry; D011247:Pregnancy; D011485:Protein Binding / Q000502:physiology; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D021122:Protein Subunits / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D024042:Collagen Type I; D024142:Collagen Type VI; D004792:Enzyme Precursors; D061965:Matrix Metalloproteinase Inhibitors; D021122:Protein Subunits; D011994:Recombinant Proteins; D003094:Collagen; D053509:Matrix Metalloproteinase 13; D053505:Matrix Metalloproteinases, Secreted; C120487:pro-matrix metalloproteinase 9; D019278:Matrix Metalloproteinase 3; D020778:Matrix Metalloproteinase 2; C488762:MMP8 protein, human; D020784:Matrix Metalloproteinase 8; D020780:Matrix Metalloproteinase 9; D020781:Matrix Metalloproteinase 1