Background: Statins may improve left ventricular remodeling after myocardial infarction. We tested whether statins inhibit cardiomyocyte apoptosis through glycogen synthase kinase 3beta (GSK3beta) inactivation and evaluated activation of downstream transcription factors.
Methods/results: Mevastatin and pravastatin activated serine/threonine kinase Akt in neonatal cardiomyocytes dose and time dependently with maximal activation at 15 min/10 microM. Caspase-3 activity was induced 2.73 +/- 0.29-fold by 6 h of hypoxia followed by 18 h of reoxygenation. Pravastatin added at the beginning of the reoxygenation period reduced caspase-3 activation to 1.26 +/- 0.06-fold compared to control cells (P < 0.001). Similar results were obtained for mevastatin (decreased to 1.98 +/- 0.45-fold, P < 0.05). TUNEL staining of neonatal cardiomyocytes after 24 h reoxygenation and 4',6'-diamidino-2-phenylindole staining of adult rat cardiomyocytes after 6 h H(2)O(2) showed reduced cardiomyocyte apoptosis in the presence of statin. Analysis of signaling pathways downstream of Akt revealed phosphorylation of GSK3beta. Transcription factor cAMP-responsive element binding (CREB) protein showed weak phosphorylation at serine 133; transcription factor NF-kappaB was not significantly activated after statin treatment as evaluated by EMSA. The GSK3beta target protein beta-catenin was stabilized at 3 h after statin treatment both in neonatal as well as adult rat cardiomyocytes. Transfection with constitutive active GSK3betaS9A sensitized neonatal cardiomyocytes to hypoxia/reoxygenation-induced apoptosis as measured by annexin V/propidium iodide staining. Furthermore, myocardial protein extracts of mice revealed GSK3beta inactivation after administration of pravastatin intraperitoneally.
Conclusions: Statins inhibit cardiomyocyte apoptosis in association with GSK3beta inactivation. Inactivation of GSK3beta leads to stabilization of beta-catenin in cardiomyocytes.