Heat shock protein 72 enhances manganese superoxide dismutase activity during myocardial ischemia-reperfusion injury, associated with mitochondrial protection and apoptosis reduction.
BACKGROUND
Heat shock protein 72 (HSP72) is known to provide myocardial protection against ischemia-reperfusion injury by its chaperoning function. Target molecules of this effect are presumed to include not only structural proteins but also other self-preservation proteins. The details, however, remain unknown. Manganese superoxide dismutase (Mn-SOD) is an enzyme that preserves mitochondria, a key organelle for cellular respiration, from reperfusion injury and limits mitochondria-related apoptosis. We hypothesized that Mn-SOD would play a role in HSP72-mediated cardioprotection.


RESULTS
Rat hearts were transfected with human HSP72 by intra-coronary infusion of Hemagglutinating Virus of Japan-liposome, resulting in global myocardial overexpression of HSP72. After ischemia-reperfusion injury, cardiac function (left ventricular systolic pressure, maximum dP/dt, minimum dP/dt, and coronary flow) was improved in the HSP72-transfected hearts compared with control-transfected ones, corresponding with less leakage of creatine kinase and mitochondrial aspartate aminotransferase. Postischemic Mn-SOD content and activity in the HSP72-transfected hearts were enhanced in comparison with the controls (content: 96.9+/-4.1 versus 85.5+/-2.5% to the preischemic level, P=0.038; activity: 93.9+/-2.2 versus 82.2+/-3.7%, P=0.022), associated with improved mitochondrial respiratory function (postischemic percent respiratory control index; NAD(+)-linked: 81.3+/-3.8 versus 18.5+/-4.4%; FAD-linked: 71.8+/-5.5 versus 20.7+/-5.3%, P<0.001). In addition, incidence of postischemic cardiomyocyte apoptosis was attenuated in the HSP72-transfected hearts (4.0+/-1.1 versus 10.3+/-3.3%, P=0.036), correlating with an increased Bcl-2 level and reduced up-regulation of caspase-3.


CONCLUSIONS
These data suggest that the enhanced Mn-SOD activity during ischemia-reperfusion injury, which is associated with mitochondrial protection and apoptosis reduction, is a possible mechanism of HSP72-induced cardioprotection.
D000818:Animals; D017209:Apoptosis; D002316:Cardiotonic Agents; D004789:Enzyme Activation; D050884:HSP72 Heat-Shock Proteins; D006321:Heart / Q000503:physiopathology; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D051381:Rats; D011917:Rats, Inbred Lew; D013482:Superoxide Dismutase / Q000378:metabolism*; D014162:Transfection
D002316:Cardiotonic Agents; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D013482:Superoxide Dismutase