title: Chronic hypoxia inhibits MMP-2 activation and cellular invasion in human cardiac myofibroblasts.
abstract: Cardiac myofibroblasts are pivotal to adaptive remodelling after myocardial infarction (MI). These normally quiescent cells invade and proliferate as a wound healing response, facilitated by activation of matrix metalloproteinases, particularly MMP-2. Following MI these reparative events occur under chronically hypoxic conditions yet the mechanisms by which hypoxia might modulate MMP-2 activation and cardiac myofibroblast invasion have not been investigated. Human cardiac myofibroblasts cultured in collagen-supplemented medium were exposed to normoxia (20% O(2)) or hypoxia (1% O(2)) for up to 48 h. Secreted levels of total and active MMP-2 were quantified using gelatin zymography, TIMP-2 and membrane-associated MT1-MMP were quantified with ELISA, whole cell MT1-MMP by immunoblotting and immunocytochemistry and MT1-MMP mRNA with real-time RT-PCR. Cellular invasion was assessed in modified Boyden chambers and migration by scratch wound assay. In the human cardiac myofibroblast, MT1-MMP was central to MMP-2 activation and activated MMP-2 necessary for invasion, confirmed by gene silencing. MMP-2 activation was substantially attenuated by hypoxia (P<0.001), paralleled by inhibition of myofibroblast invasion (P<0.05). In contrast, migration was independent of either MT1-MMP or MMP-2. Reduced membrane expression of MT1-MMP (P<0.05) was responsible for the hypoxic reduction of MMP-2 activation, with no change in either total MMP-2 or TIMP-2. In conclusion, hypoxia reduces MMP-2 activation and subsequent invasion of human cardiac myofibroblasts by reducing membrane expression of MT1-MMP and may delay healing after MI. Regulation of these MMPs remains an attractive target for therapeutic intervention.
authors.affiliation: Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Riches
authors.forename: Michael E
authors.initials: ME
authors.lastname: Morley
authors.forename: Neil A
authors.initials: NA
authors.lastname: Turner
authors.forename: David J
authors.initials: DJ
authors.lastname: O'Regan
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Ball
authors.forename: Chris
authors.initials: C
authors.lastname: Peers
authors.forename: Karen E
authors.initials: KE
authors.lastname: Porter
mesh_terms: D002465:Cell Movement; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014945:Wound Healing
chemical_list: D019716:Tissue Inhibitor of Metalloproteinase-2; D003094:Collagen; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14