Abstract 12999: Senescence Marker Protein 30 Protect the Cardiac Injury From After Ischemia Reperfusion

Background: Successful myocardial reperfusion is effective therapy for improving the clinical outcome after acute myocardial infarction, nevertheless reperfusion injury can paradoxically induces cardiomyocyte dysfunction. Moreover, recovery of cardiac function is impaired with aging. Glycogen synthase kinase-3β (GSK-3β) and p70 ribosomal S6 kinase (p70S6K) are cardioprotective against I/R via mitochondrial dysfunction. Senescence marker protein-30 (SMP30), which regulates mitochondrial quality and decreases with aging, is an organ-protective protein; however the protective role of SMP30 against ischemia/reperfusion (I/R) has not been clearly determined yet. Methods and Result: Firstly, we confirmed that SMP30 expressions in the heart were progressively decreased with aging. In vitro study, we also found that reactive oxygen species decreased expression levels of SMP30 in neonatal cardiomyocyte. Depletion of SMP30 increased apoptotic cardiomyocyte death after hydrogen peroxide stimulation. To evaluate the cardioprotective role of SMP30, we induced 30 min ischemia and 24-hr reperfusion (I/R) in WT and SMP30 KO mice. Phosphorylation levels of p70S6K and GSK-3β in the heart were increased after IR in WT mice; however those phosphorylation were attenuated in SMP30 KO mice. SMP30 KO mice after I/R had significantly larger numbers of apoptotic cardiomyocyte than WT mice ( 10.5± 5.7% vs. 4.0± 1.7%, p < 0.05), that correlated with a significant expansion in infarct size and a significant reduction of left ventricular fractional shortening (37.3± 4.3% vs 43.4± 5.1%, p < 0.01). Conclusions: These results suggest that reduction of SMP30 levels with aging is associated with age-related dysfunction after ischemia-reperfusion through disability to phosphorylate p70S6K and GSK-3β. Thus, SMP30 might be a novel therapeutic target for the treatment of acute myocardial infarction in elderly patient.