Thirunavukkarasu Mahesh, Han Zhihua, Zhan Lijun, Penumathsa Suresh Varma, Menon Venugopal P, Maulik Nilanjana
Molecular Cardiology and Angiogenesis Laboratory, Department of Surgery, University of Connecticut Medical Center, Farmington, Connecticut 06030-1110, USA.
Antioxid Redox Signal. 2008 Aug;10(8):1475-84. doi: 10.1089/ars.2008.2042.
beta-Catenin, the downstream target of glycogen synthase kinase-3beta (GSK-3beta), 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 beta-catenin expression by intramyocardial injection of adeno-sh-RNA against beta-catenin (BCT) (4 x 10(8) 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/dt(max) (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. Realtime 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 beta-catenin abolished IP-mediated cardioprotection, probably through inhibition of VEGF-Bcl-2 and survivin.
β-连环蛋白是糖原合酶激酶-3β（GSK-3β）的下游靶点，在缺血预处理（IP）介导的心脏保护中起重要作用。在本研究中，我们通过心肌内注射针对β-连环蛋白（BCT）的腺病毒-sh-RNA（4×10⁸ pfu）抑制β-连环蛋白表达，研究IP介导的心脏保护机制。腺病毒-LacZ（LZ）用作对照。大鼠被随机分为：（a）LZ+缺血再灌注（IR）；（b）LZ+IP+IR；（c）BCT+IR；和（d）BCT+IP+IR。每组分离的心脏先进行30分钟缺血，然后再灌注2小时。两个IP+IR组的心脏在IR前进行IP（5分钟缺血+10分钟再灌注；4个循环）。与LZ+IP+IR组相比，在再灌注120分钟时，BCT+IP+IR组左心室功能恢复（78 vs. 88 mmHg）、dp/dt（max）（1802 vs. 2189 mmHg/秒）和主动脉流量（4 vs. 9 ml/分钟）显著降低。与LZ+IP+IR组相比，BCT+IP+IR组梗死面积增加（42% vs. 24%），凋亡心肌细胞增多（122 vs. 58个计数/60 HPF）。实时PCR和蛋白质印迹分析显示与LZ+IP+IR组相比，BCT+IP+IR组中VEGF、Bcl-2和survivin的mRNA和蛋白质表达显著下调。这些发现首次表明，沉默β-连环蛋白可消除IP介导的心脏保护作用，可能是通过抑制VEGF-Bcl-2和survivin来实现的。
