Dept. of Veterinary Physiology, Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National Univ., Gwangju 500-757, Korea.
Am J Physiol Cell Physiol. 2010 Apr;298(4):C847-56. doi: 10.1152/ajpcell.00418.2009. Epub 2010 Jan 20.
Here we show that the effect of hypoxia on human umbilical cord blood mesenchymal stem cell (hMSC) migration is via the modulation of focal adhesion kinase (FAK) and its related signaling pathways. Hypoxia increased hMSC migration and cell viability, whereas lactate dehydrogenase (LDH) release was not affected for up to 48 h (data not shown). In addition, hypoxia increased the level of reactive oxygen species (ROS) generation in a time-dependent manner. Hypoxia-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and stress-activated protein kinase/c-Jun NH(2)-terminal kinase (SAPK/JNK) were inhibited by the antioxidant (N-acetylcysteine, NAC, 10(-6) M) and (taurine, 4x10(-6) M). Hypoxia-induced endothelial nitric oxide synthase (eNOS) phosphorylation was regulated by p38 MAPK and SAPK/JNK activation. In addition, hypoxia increased the level of hypoxia inducible factor (HIF)-1alpha expression, which was blocked by inhibition of eNOS. Also, hypoxia-induced expression of Flk-1, vascular endothelial growth factor (VEGF), and its secreted form were inhibited by HIF-1alpha small interfering RNA (siRNA). In this hypoxic condition, FAK and Src phosphorylation were increased in a time-dependent manner. Inhibition of Src with specific inhibitor (PP2, 10(-8) M) blocked hypoxia-induced FAK activation. Subsequently, hypoxia-induced FAK phosphorylation was blocked by VEGF siRNA. Finally, hypoxia-induced increase of hMSC migration was inhibited by FAK siRNA. The results indicate that hypoxia increases migration of hMSCs via VEGF-mediated FAK phospholylation and involves the cooperative activity of the ROS, MAPK, eNOS and HIF-1alpha pathways.
在这里，我们证明了低氧环境对人脐带血间充质干细胞（hMSC）迁移的影响是通过调节粘着斑激酶（FAK）及其相关信号通路实现的。低氧增加了 hMSC 的迁移和细胞活力，而乳酸脱氢酶（LDH）的释放在 48 小时内没有受到影响（未显示数据）。此外，低氧以时间依赖性方式增加了活性氧（ROS）的产生水平。低氧诱导的丝裂原活化蛋白激酶（MAPK）p38 和应激激活蛋白激酶/c-Jun N 末端激酶（SAPK/JNK）磷酸化被抗氧化剂（N-乙酰半胱氨酸，NAC，10（-6）M）和（牛磺酸，4x10（-6）M）抑制。低氧诱导的内皮型一氧化氮合酶（eNOS）磷酸化受 p38 MAPK 和 SAPK/JNK 激活的调节。此外，低氧增加了缺氧诱导因子（HIF）-1α的表达水平，而 eNOS 的抑制则阻断了这一过程。此外，低氧诱导的 Flk-1、血管内皮生长因子（VEGF）及其分泌形式的表达也被 HIF-1α 小干扰 RNA（siRNA）抑制。在这种低氧条件下，FAK 和Src 的磷酸化呈时间依赖性增加。用特异性抑制剂（PP2，10（-8）M）抑制 Src 可阻断低氧诱导的 FAK 激活。随后，VEGF siRNA 阻断了低氧诱导的 FAK 磷酸化。最后，FAK siRNA 抑制了低氧诱导的 hMSC 迁移增加。结果表明，低氧通过 VEGF 介导的 FAK 磷酸化增加 hMSC 的迁移，并涉及 ROS、MAPK、eNOS 和 HIF-1α 途径的协同作用。
