Adeno-sh-β-Catenin Abolishes Ischemic Preconditioning–Mediated Cardioprotection by Downregulation of Its Target Genes VEGF Bcl-2 and Survivin in Ischemic Rat Myocardium

摘要

β-Catenin, the downstream target of glycogen synthase kinase-3β (GSK-3β), plays a vital role in ischemic preconditioning (IP)-mediated cardioprotection. In the present study, we investigated the mechanism of IP-mediated cardioprotection through suppression of β-catenin expression by intramyocardial injection of adeno-sh-RNA against β-catenin (BCT) (4 × 10⁸ pfu). Adeno-LacZ (LZ) was used as control. The rats were randomized into (a) LZ + ischemia–reperfusion (IR); (b) LZIPIR; (c) BCTIR; and (d) BCTIPIR. Isolated hearts from each group were subjected to 30 min of I followed by 2 h of R. Both IPIR group hearts were subjected to IP (5 min I + 10 min R; four cycles) before IR. Significant reduction in left ventricular functional recovery (78 vs. 88 mm Hg), dp/dtmax (1,802 vs. 2,189 mm Hg/sec), and aortic flow (4 vs. 9 ml/min) was observed in BCTIPIR compared with LZIPIR at 120 min of reperfusion. Increased infarct size (42 vs. 24%) and apoptotic cardiomyocytes (122 vs. 58 counts/60 HPF) were observed in BCTIPIR compared with LZIPIR. Real-time PCR and Western blot analysis showed significant downregulation in mRNA and protein expression of VEGF, Bcl-2, and survivin in BCTIPIR compared with LZIPIR. These findings indicated for the first time that silencing β-catenin abolished IP-mediated cardioprotection, probably through inhibition of VEGF-Bcl-2 and survivin. Antioxid. Redox Signal. 10, 1475–1485.