Submitted on August 7, 2007
Accepted on December 4, 2007
Interruption of Endothelin Signaling Modifies Membrane Type-1 Matrix Metalloproteinase Activity during Ischemia and Reperfusion
Anne M Deschamps1, Juozas Zavadzkas2, Rebecca L Murphy1, Christine N Koval1, Julie E McLean1, Laura Jeffords1, Stuart Saunders1, Nina Sheats1, Robert E. Stroud1, and Francis G. Spinale2*
1 Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, South Dakota, United States
2 Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, South Carolina, United States
* To whom correspondence should be addressed. E-mail: wilburnm{at}musc.edu.
Background: The matrix metalloproteinases (MMPs), in particular, membrane-type 1 MMP (MT1-MMP), are increased in the context of myocardial ischemia and reperfusion (I/R) and likely contribute to myocardial dysfunction. One potential upstream induction mechanism for MT1-MMP is endothelin (ET) release and subsequent protein kinase C (PKC) activation. Modulation of ET and PKC signaling with respect to MT1-MMP activity with I/R has yet to be explored. Accordingly, this study examined in vivo MT1-MMP activation during I/R following modification of ET signaling and PKC activation.
Methods and Results: Using a novel fluorogenic microdialysis system, myocardial interstitial MT1-MMP activity was measured in pigs (30kg/n=9) during I/R (90min-I/120min-R). Local ETA receptor antagonism (BQ123, 1µM) and PKC inhibition (Chelerythrine, 1µM) was performed in parallel microdialysis probes. MT1-MMP activity was increased during I/R by 122±10% (p<0.05) and was unchanged from baseline with ET antagonism and/or PKC inhibition. Selective PKC isoform induction occurred such that PKC beta II increased by 198±31% (p<0.05). MT1-MMP phosphothreonine, a putative PKC phosphorylation site, was increased by 121±8% (p<0.05) in the I/R region.
Conclusions: These studies demonstrate for the first time that increased interstitial MT1-MMP activity during I/R is a result of the ET/PKC pathway and may be due to enhanced phosphorylation of MT1-MMP. These findings identify multiple potential targets for modulating a local proteolytic pathway operative during I/R.
