Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC.
Arterioscler Thromb Vasc Biol. 2013 Apr;33(4):785-94. doi: 10.1161/ATVBAHA.112.301143. Epub 2013 Feb 7.
Increased cardiac stromal cell-derived factor-1α (SDF-1α) expression promotes neovascularization and myocardial repair after ischemic injury through recruiting stem cells and reducing cardiomyocyte death. Previous studies have shown that heme oxygenase-1 and its reaction byproduct, carbon monoxide (CO), induce SDF-1α expression in ischemic heart. However, the mechanism underlying heme oxygenase-1/CO-induced cardiac SDF-1α expression remains elusive. This study aims to investigate the signaling pathway and the transcriptional factor that mediate CO-induced SDF-1α gene expression and cardioprotection.
CO gas and a CO-releasing compound, tricarbonyldichlororuthenium (II) dimer, dose-dependently induced SDF-1α expression in primary neonatal cardiomyocytes and H9C2 cardiomyoblasts. Promoter luciferase-reporter assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation demonstrated that the activator protein 2α (AP-2α) mediated tricarbonyldichlororuthenium (II) dimer-induced SDF-1α gene transcription. Tricarbonyldichlororuthenium (II) dimer induced AP-2α expression via protein kinase B (AKT)-dependent signaling. AKT inhibition or AP-2α knockdown reduced tricarbonyldichlororuthenium (II) dimer-induced SDF-1α expression. Coronary ligation induced transient increases of cardiac AP-2α and SDF-1α expression, which were declined at 1 week postinfarction in mice. Periodic exposure of coronary-ligated mice to CO (250 ppm for 1 hour/day, 6 days) resumed the induction of AP-2α and SDF-1α gene expression in infarcted hearts. Immunohistochemistry and echocardiography performed at 4 weeks after coronary ligation revealed that CO treatment enhanced neovascularization in the myocardium of peri-infarct region and improved cardiac function. CO-mediated SDF-1α expression and cardioprotection was ablated by intramyocardial injection of lentivirus bearing specific short hairpin RNA targeting AP-2α.
Our data demonstrate that AKT-dependent upregulation of AP-2α is essential for CO-induced SDF-1α expression and myocardial repair after ischemic injury.
心肌基质细胞衍生因子-1α（SDF-1α）表达增加可通过募集干细胞和减少心肌细胞死亡来促进缺血性损伤后的新生血管形成和心肌修复。先前的研究表明血红素加氧酶-1（HO-1）及其反应副产物一氧化碳（CO）诱导缺血心脏中 SDF-1α的表达。然而，HO-1/CO 诱导心脏 SDF-1α表达的机制尚不清楚。本研究旨在探讨介导 CO 诱导 SDF-1α 基因表达和心脏保护作用的信号通路和转录因子。
CO 气体和一氧化碳释放化合物三羰基二氯钌（II）二聚体可剂量依赖性地诱导原代新生心肌细胞和 H9C2 心肌细胞中 SDF-1α 的表达。启动子荧光素酶报告基因检测、电泳迁移率变动分析和染色质免疫沉淀实验表明，激活蛋白 2α（AP-2α）介导三羰基二氯钌（II）二聚体诱导 SDF-1α 基因转录。三羰基二氯钌（II）二聚体通过蛋白激酶 B（AKT）依赖性信号诱导 AP-2α 的表达。AKT 抑制或 AP-2α 敲低减少了三羰基二氯钌（II）二聚体诱导的 SDF-1α 表达。结扎冠状动脉可诱导心脏 AP-2α 和 SDF-1α 表达的短暂增加，在心肌梗死 1 周后，这种表达减少。对冠状动脉结扎小鼠进行周期性 CO（250 ppm，每天 1 小时）暴露可恢复梗死心脏中 AP-2α 和 SDF-1α 基因的诱导表达。在冠状动脉结扎后 4 周进行的免疫组织化学和超声心动图检查显示，CO 处理可增强梗死区心肌的新生血管形成，并改善心功能。用携带针对 AP-2α 的特异性短发夹 RNA 的慢病毒进行心肌内注射可消除 CO 介导的 SDF-1α 表达和心脏保护作用。
我们的数据表明，AKT 依赖性上调 AP-2α 对于 CO 诱导的缺血性损伤后 SDF-1α 表达和心肌修复是必需的。
