title: Low-dose spironolactone prevents apoptosis repressor with caspase recruitment domain degradation during myocardial infarction.
abstract: Low-dose mineralocorticoid receptor antagonists reduce morbidity and mortality in patients with heart failure and myocardial infarction, despite normal plasma aldosterone levels. Since apoptosis plays an important role in heart failure and postinfarction left ventricular remodeling, we examined whether low-dose mineralocorticoid receptor antagonists modulate cardiomyocyte death by regulating the apoptosis repressor protein apoptosis repressor with caspase recruitment domain to lessen the extent of apoptosis. Hearts from adult male Sprague-Dawley rats were subjected to regional ischemia followed by reperfusion ex vivo, with mineralocorticoid receptor antagonists added to perfusates before ischemia. Low-dose spironolactone (10 nmol/L) or eplerenone (100 nmol/L) significantly reduced infarct size. Spironolactone also prevented cleavage of the apoptotic chromatin condensation inducer in the nucleus and of the inhibitor of caspase-activated DNAse induced by ischemia-reperfusion, thereby abolishing chromatin condensation and internucleosomal cleavage. Ischemia-reperfusion-induced activation of caspases 2, 3, and 9, but not caspase 8, was prevented by spironolactone, suggesting targeted regulation of the intrinsic pathway. Low-dose spironolactone and eplerenone prevented loss of the apoptosis repressor with the caspase recruitment domain and reduced myocyte death. In H9c2 cells, mineralocorticoid receptor activation by aldosterone resulted in apoptosis repressor with caspase recruitment domain degradation and enhanced apoptosis; these actions were prevented by coadministration of spironolactone. Using a triple lysine mutant we identified that aldosterone enhances posttranscriptional degradation of the apoptosis repressor with a caspase recruitment domain via the ubiquitin-proteasomal pathway. Our data demonstrate that low-dose mineralocorticoid receptor antagonists reduce infarct size and apoptosis in the reperfused myocardium by preventing the apoptosis repressor with caspase recruitment domain degradation.
authors.affiliation: Department of Cardiology, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Thi Yen
authors.initials: TY
authors.lastname: Loan Le
authors.forename: Mahidi
authors.initials: M
authors.lastname: Mardini
authors.forename: Viive M
authors.initials: VM
authors.lastname: Howell
authors.forename: John W
authors.initials: JW
authors.lastname: Funder
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Ashton
authors.forename: Anastasia S
authors.initials: AS
authors.lastname: Mihailidou
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D053143:Caspase 2 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D000077545:Eplerenone; D015151:Immunoblotting; D066298:In Vitro Techniques; D008297:Male; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009203:Myocardial Infarction / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control*; D059748:Proteolysis / Q000187:drug effects; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D018161:Receptors, Mineralocorticoid / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013148:Spironolactone / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D000451:Mineralocorticoid Receptor Antagonists; D009124:Muscle Proteins; C491788:Nol3 protein, rat; D018161:Receptors, Mineralocorticoid; C109664:caspase-activated DNase inhibitor; D013148:Spironolactone; D000077545:Eplerenone; D053143:Caspase 2; D053148:Caspase 3; D053453:Caspase 9