Chronic hypoxia inhibits MMP-2 activation and cellular invasion in human cardiac myofibroblasts

J Mol Cell Cardiol. 2009 Sep;47(3):391-9. doi: 10.1016/j.yjmcc.2009.06.002. Epub 2009 Jun 11.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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

Substances

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