Kuo Hsuan-Fu, Liu Po-Len, Chong Inn-Wen, Liu Yu-Peng, Chen Yung-Hsiang, Ku Po-Ming, Li Chia-Yang, Chen Hsiu-Hua, Chiang Hui-Ching, Wang Chiao-Lin, Chen Huang-Jen, Chen Yen-Chieh, Hsieh Chong-Chao
Department of Internal Medicine, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, 801, Taiwan.
Department of Respiratory Therapy, College of Medicine, Kaohsiung Medical University, Kaohsiung, 807, Taiwan.
PLoS One. 2016 May 24;11(5):e0156059. doi: 10.1371/journal.pone.0156059. eCollection 2016.
Pigment epithelium-derived factor (PEDF) is a multifunctional protein that exhibits anti-angiogenic, antitumor, anti-inflammatory, antioxidative, anti-atherogenic, and cardioprotective properties. While it was recently shown that PEDF expression is inhibited under low oxygen conditions, the functional role of PEDF in response to hypoxia/reoxygenation (H/R) remains unclear. The goal of this study was to therefore investigate the influence of PEDF on myocardial H/R injury. For these analyses, PEDF-specific small interfering RNA-expressing and PEDF-expressing lentivirus (PEDF-LV) vectors were utilized to knockdown or stably overexpress PEDF, respectively, within human cardiomyocytes (HCM) in vitro. We noted that reactive oxygen species (ROS) play important roles in the induction of cell death pathways, including apoptosis and autophagy in ischemic hearts. Our findings demonstrate that overexpression of PEDF resulted in a significant reduction in ROS production and attenuation of mitochondrial membrane potential depletion under H/R conditions. Furthermore, PEDF inhibited the activation of a two-step apoptotic pathway in which caspase-dependent (caspase-9 and caspase-3) and caspase-independent (apoptosis inducing factor and endonuclease G), which in turn cleaves several crucial substrates including the DNA repair enzyme poly (ADP-ribose) polymerase. Meanwhile, overexpression of PEDF also promoted autophagy, a process that is typically activated in response to H/R. Therefore, these findings suggest that PEDF plays a critical role in preventing H/R injury by modulating anti-oxidant and anti-apoptotic factors and promoting autophagy.
色素上皮衍生因子（PEDF）是一种多功能蛋白质，具有抗血管生成、抗肿瘤、抗炎、抗氧化、抗动脉粥样硬化和心脏保护特性。虽然最近研究表明低氧条件下PEDF表达受到抑制，但PEDF在缺氧/复氧（H/R）反应中的功能作用仍不清楚。因此，本研究的目的是探讨PEDF对心肌H/R损伤的影响。为进行这些分析，分别利用表达PEDF特异性小干扰RNA和表达PEDF的慢病毒（PEDF-LV）载体在体外人心肌细胞（HCM）中敲低或稳定过表达PEDF。我们注意到活性氧（ROS）在诱导细胞死亡途径中起重要作用，包括缺血心脏中的凋亡和自噬。我们的研究结果表明，PEDF过表达导致H/R条件下ROS产生显著减少和线粒体膜电位耗竭减弱。此外，PEDF抑制了两步凋亡途径的激活，其中包括半胱天冬酶依赖性（半胱天冬酶-9和半胱天冬酶-3）和半胱天冬酶非依赖性（凋亡诱导因子和核酸内切酶G），进而切割包括DNA修复酶聚（ADP-核糖）聚合酶在内的几种关键底物。同时，PEDF过表达还促进了自噬，这一过程通常在H/R反应中被激活。因此，这些研究结果表明，PEDF通过调节抗氧化和抗凋亡因子以及促进自噬在预防H/R损伤中起关键作用。
