IGF-1 degradation by mast cell chymase promotes delayed cell death in post-ischemic hearts
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ABSTRACT: Coronary heart disease is the leading cause of death worldwide. After an acute myocardial infarction, early reperfusion reduces infarct size, which correlates with improved clinical outcomes. Paradoxically, reperfusion although relieving ischemia, accelerates apoptosis in injured cardiomyocytes, which has led to the view that myocardial salvage is futile beyond the first few hours of reperfusion. In murine hearts subjected to 90 min of coronary artery occlusion and then 48 h of reperfusion, we show transient activation of intrinsic prosurvival insulin-like growth factor-1 (IGF-1) signaling. In these hearts, acute IGF-1 receptor inhibition decreases the abundance of prosurvival signaling molecules, and markedly activates caspase-3, a potent effector of apoptosis, in infarct border zone cardiomyocytes. We found that mouse mast cell protease-4 (MMCP-4) degraded IGF-1 in vitro by a novel catalytic activity of chymases. In vivo, this degradation, which is triggered by mast cell infiltration into the peri-infarct region and MMCP-4 extravasation, between 48 and 72 h post-ischemia/reperfusion (I/R), attenuates IGF-1 prosurvival signaling. In MMCP-4-deficient mice, while infarct size is not reduced at 24 h post-I/R, at 72 h post-I/R myocardial IGF-1 levels and signaling are increased, resulting in activation of the survival kinases Akt and ERK, inhibition of caspase-3, and reduced myocardial cell death. As a consequence, I/R-mediated loss of viable myocardium, adverse cardiac remodeling and contractile impairment are markedly reduced. Cardiomyocyte survival with consequent myocardial salvage may thus be possible even days after an ischemic insult, making them a novel therapeutic target for delayed cardioprotective therapy. Group 1 is wild type C57Bl6 uninjured hearts. These mice were not undergone any surgery and used as controls. Group 2 are wild type C57Bl6 72 h post-ischemia reperfusion (IR) injury hearts. These mice for subjected to ischemia reperfusion (IR) involving 90 min of left anterior descending coronary artery occlusion followed by reperfusion for 3 days or 72 h.
ORGANISM(S): Mus musculus
SUBMITTER: Gregory Doho
PROVIDER: E-GEOD-61592 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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