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: Kirsten Riches, Michael E Morley, Neil A Turner, David J O'Regan, Stephen G Ball, Chris Peers, Karen E Porter
• Journal: Journal of molecular and cellular cardiology (J Mol Cell Cardiol) Vol. 47 Issue 3 Pg. 391-9 (Sep 2009) ISSN: 1095-8584 [Electronic] England
• PMID: 19523958 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Tissue Inhibitor of Metalloproteinase-2
• Collagen
• Matrix Metalloproteinase 2
• Matrix Metalloproteinase 14

Topics

• Cell Movement
• Cells, Cultured
• Collagen (metabolism)
• Enzyme Activation
• Fibroblasts (metabolism)
• Humans
• Hypoxia (metabolism)
• Lysosomes (metabolism)
• Matrix Metalloproteinase 14 (metabolism)
• Matrix Metalloproteinase 2 (metabolism)
• Models, Biological
• Neoplasm Invasiveness
• Reverse Transcriptase Polymerase Chain Reaction
• Tissue Inhibitor of Metalloproteinase-2 (metabolism)
• Wound Healing