title: Matrix metalloproteinase-2-deficient fibroblasts exhibit an alteration in the fibrotic response to connective tissue growth factor/CCN2 because of an increase in the levels of endogenous fibronectin.
abstract: Matrix metalloproteinase-2 (MMP-2) is an important extracellular matrix remodeling enzyme, and it has been involved in different fibrotic disorders. The connective tissue growth factor (CTGF/CCN2), which is increased in these pathologies, induces the production of extracellular matrix proteins. To understand the fibrotic process observed in diverse pathologies, we analyzed the fibroblast response to CTGF when MMP-2 activity is inhibited. CTGF increased fibronectin (FN) amount, MMP-2 mRNA expression, and gelatinase activity in 3T3 cells. When MMP-2 activity was inhibited either by the metalloproteinase inhibitor GM-6001 or in MMP-2-deficient fibroblasts, an increase in the basal amount of FN together with a decrease of its levels in response to CTGF was observed. This paradoxical effect could be explained by the fact that the excess of FN could block the access to other ligands, such as CTGF, to integrins. This effect was emulated in fibroblasts by adding exogenous FN or RGDS peptides or using anti-integrin alpha(V) subunit-blocking antibodies. Additionally, in MMP-2-deficient cells CTGF did not induce the formation of stress fibers, focal adhesion sites, and ERK phosphorylation. Anti-integrin alpha(V) subunit-blocking antibodies inhibited ERK phosphorylation in control cells. Finally, in MMP-2-deficient cells, FN mRNA expression was not affected by CTGF, but degradation of (125)I-FN was increased. These results suggest that expression, regulation, and activity of MMP-2 can play an important role in the initial steps of fibrosis and shows that FN levels can regulate the cellular response to CTGF.
authors.affiliation: Centro de Regulación Celular y Patología, Centro de Regeneración y Envejecimiento, Departamento de Biología Celular y Molecular, Millenium Institute for Fundamental and Applied Biology, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
authors.forename: Cristian A
authors.initials: CA
authors.lastname: Droppelmann
authors.affiliation: Centro de Regulación Celular y Patología, Centro de Regeneración y Envejecimiento, Departamento de Biología Celular y Molecular, Millenium Institute for Fundamental and Applied Biology, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
authors.forename: Jaime
authors.initials: J
authors.lastname: Gutiérrez
authors.affiliation: Centro de Regulación Celular y Patología, Centro de Regeneración y Envejecimiento, Departamento de Biología Celular y Molecular, Millenium Institute for Fundamental and Applied Biology, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Vial
authors.affiliation: Centro de Regulación Celular y Patología, Centro de Regeneración y Envejecimiento, Departamento de Biología Celular y Molecular, Millenium Institute for Fundamental and Applied Biology, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile. Electronic address: ebrandan@bio.puc.cl.
authors.forename: Enrique
authors.initials: E
authors.lastname: Brandan
mesh_terms: D000818:Animals; D055513:Connective Tissue Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D004151:Dipeptides / Q000494:pharmacology; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000201:enzymology*; D005353:Fibronectins / Q000096:biosynthesis* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects* / Q000502:physiology; D039564:Integrin alphaV / Q000235:genetics / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D041681:NIH 3T3 Cells; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011480:Protease Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D022502:Stress Fibers / Q000235:genetics / Q000378:metabolism*
chemical_list: C526318:CCN2 protein, mouse; D004151:Dipeptides; D005353:Fibronectins; D039564:Integrin alphaV; D061965:Matrix Metalloproteinase Inhibitors; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011480:Protease Inhibitors; D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse