Cai Yin, Ying Fan, Liu Hao, Ge Liang, Song Erfei, Wang Lin, Zhang Dengwen, Hoi Ching Tang Eva, Xia Zhengyuan, Irwin Michael G
Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China.
Department of Cardiology, Guangzhou Institute of Cardiovascular Disease, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
FASEB J. 2020 Mar;34(3):4482-4496. doi: 10.1096/fj.201901592RR. Epub 2020 Feb 5.
Ischemic heart disease is a leading cause of morbidity and mortality. Repressor activator protein 1 (Rap1), an established telomere-associated protein, is a novel modulator of hypoxia-induced apoptosis. This study aimed to explore the potential direct role of Rap1 in myocardial ischemia/reperfusion injury (I/RI) and to determine the underlying molecular mechanism. In a mouse model of myocardial I/RI (30-min of left descending coronary artery ligation followed by 2-h reperfusion), Rap1 deficiency significantly reduced myocardial infarct size (IS) and improved cardiac systolic/diastolic function. This was associated with a reduction in apoptosis in the post-ischemic myocardium. In H9C2 and primary cardiomyocytes, Rap1 knockdown or knockout significantly suppressed hypoxia/reoxygenation (H/R)-induced cell injury and apoptosis through increasing the phosphorylation/activation of STAT3 at site Ser and translocation of STAT3 to the nucleus. We surmise this since Stattic (selective STAT3 inhibitor) pretreatment canceled the abovementioned protective effect. Furthermore, co-immunoprecipitation assay revealed a direct interaction between Rap1 and STAT3, but not JAK2, suggesting that the association of Rap1 with STAT3 may contribute to the reduced activity of STAT3 (Ser ) upon H/R stimulation. In conclusion, Rap1 deficiency protects the heart from ischemic damage through STAT3-dependent reduction of cardiomyocyte apoptosis, which may yield viable target for pharmacological intervention in ischemic heart disease.
缺血性心脏病是发病和死亡的主要原因。阻遏激活蛋白1（Rap1）是一种已确定的端粒相关蛋白，是缺氧诱导凋亡的新型调节因子。本研究旨在探讨Rap1在心肌缺血/再灌注损伤（I/RI）中的潜在直接作用，并确定其潜在的分子机制。在心肌I/RI小鼠模型（左冠状动脉结扎30分钟，随后再灌注2小时）中，Rap1缺陷显著减小了心肌梗死面积（IS），并改善了心脏的收缩/舒张功能。这与缺血后心肌细胞凋亡减少有关。在H9C2细胞和原代心肌细胞中，Rap1基因敲低或敲除通过增加信号转导和转录激活因子3（STAT3）在Ser位点的磷酸化/激活以及STAT3向细胞核的转位，显著抑制了缺氧/复氧（H/R）诱导的细胞损伤和凋亡。我们之所以这样推测，是因为Stattic（选择性STAT3抑制剂）预处理消除了上述保护作用。此外，免疫共沉淀分析显示Rap1与STAT3之间存在直接相互作用，但与Janus激酶2（JAK2）不存在直接相互作用，这表明Rap1与STAT3的结合可能导致H/R刺激后STAT3（Ser）活性降低。总之，Rap1缺陷通过依赖STAT3减少心肌细胞凋亡来保护心脏免受缺血损伤，这可能为缺血性心脏病的药物干预提供可行的靶点。
