Division of Pediatric Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, 53226, USA.
Am J Physiol Cell Physiol. 2012 Jan 15;302(2):C383-91. doi: 10.1152/ajpcell.00164.2011. Epub 2011 Oct 26.
Angiogenesis plays critical roles in the recovery phase of ischemic heart disease and peripheral vascular disease. An increase in autophagy is protective under hypoxic and chronic ischemic conditions. In the present study we determined the role of autophagy in angiogenesis. 3-Methyladenine (3-MA) and small interfering RNA (siRNA) against ATG5 were used to inhibit autophagy induced by nutrient deprivation of cultured bovine aortic endothelial cells (BAECs). Assays of BAECs tube formation and cell migration revealed that inhibition of autophagy by 3-MA or siRNA against ATG5 reduced angiogenesis. In contrast, induction of autophagy by overexpression of ATG5 increased BAECs tube formation and migration. Additionally, inhibiting autophagy impaired vascular endothelial growth factor (VEGF)-induced angiogenesis. However, inhibition of autophagy did not alter the expression of pro-angiogenesis factors such as VEGF, platelet-derived growth factor, or integrin αV. Furthermore, autophagy increased reactive oxygen species (ROS) formation and activated AKT phosphorylation. Inhibition of autophagy significantly decreased the production of ROS and activation of AKT but not of extracellular regulated kinase, whereas overexpression of ATG5 increased cellular ROS production and AKT activation in BAECs. Inhibition of AKT activation or ROS production significantly decreased the tube formation induced by ATG5 overexpression. Here we report a novel observation that autophagy plays an important role in angiogenesis in BAECs. Induction of autophagy promotes angiogenesis while inhibition of autophagy suppresses angiogenesis, including VEGF-induced angiogenesis. ROS production and AKT activation might be important mechanisms for mediating angiogenesis induced by autophagy. Our findings indicate that targeting autophagy may provide an important new tool for treating cardiovascular disease.
血管生成在缺血性心脏病和外周血管疾病的恢复阶段发挥着关键作用。在缺氧和慢性缺血条件下，自噬的增加具有保护作用。在本研究中，我们确定了自噬在血管生成中的作用。3-甲基腺嘌呤（3-MA）和针对 ATG5 的小干扰 RNA（siRNA）用于抑制培养的牛主动脉内皮细胞（BAEC）营养剥夺诱导的自噬。BAEC 管形成和细胞迁移测定显示，3-MA 或针对 ATG5 的 siRNA 抑制自噬可减少血管生成。相比之下，通过过表达 ATG5 诱导自噬会增加 BAEC 的管形成和迁移。此外，抑制自噬会损害血管内皮生长因子（VEGF）诱导的血管生成。然而，抑制自噬不会改变促血管生成因子的表达，如 VEGF、血小板衍生生长因子或整合素αV。此外，自噬会增加活性氧（ROS）的形成并激活 AKT 磷酸化。抑制自噬会显著降低 ROS 的产生和 AKT 的激活，但不会降低细胞外调节激酶的激活，而 ATG5 的过表达会增加 BAEC 中的细胞 ROS 产生和 AKT 激活。抑制 AKT 激活或 ROS 产生会显著降低 ATG5 过表达诱导的管形成。在这里，我们报告了一个新的观察结果，即自噬在 BAEC 的血管生成中发挥重要作用。诱导自噬会促进血管生成，而抑制自噬会抑制血管生成，包括 VEGF 诱导的血管生成。ROS 产生和 AKT 激活可能是介导自噬诱导血管生成的重要机制。我们的发现表明，靶向自噬可能为治疗心血管疾病提供一种重要的新工具。
