MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China.
FEBS J. 2010 Nov;277(22):4789-802. doi: 10.1111/j.1742-4658.2010.07884.x. Epub 2010 Oct 6.
High-fluence low-power laser irradiation (HF-LPLI) can induce apoptosis by triggering mitochondrial oxidative stress. Signal transducer and activator of transcription 3 (Stat3) is an important transcription factor in the modulation of cell proliferation and apoptosis. Here, using real-time single-cell analysis and western blotting analysis, we investigated the changes in activities of Stat3 in COS-7 cells upon HF-LPLI (633 nm, 80 and 120 J·cm(-2)) and the underlying mechanisms involved. We found that Stat3 was significantly activated by HF-LPLI in a time-dependent and dose-dependent manner. Stat3 activation attenuated HF-LPLI-induced apoptosis, as shown by the fact that both dominant negative Stat3 (Y705F) and Stat3 small interfering RNA expression enhanced cellular apoptosis induced by HF-LPLI. Moreover, we also found that Src kinase was the major positive regulator of Stat3 activation induced by HF-LPLI. Reactive oxygen species (ROS) generation was essential for Stat3 and Src activation upon HF-LPLI, because scavenging of ROS by vitamin C or N-acetylcysteine totally abrogated the activation of Stat3 and Src. Taken together, these findings show that the ROS-Src-Stat3 pathway mediates a negative feedback inhibition of apoptosis induced by HF-LPLI in COS-7 cells. Our research will provide new insights into the mechanism of apoptosis caused by HF-LPLI, and also extend the functional study of Stat3.
高能量低强度激光照射（HF-LPLI）通过触发线粒体氧化应激诱导细胞凋亡。信号转导和转录激活因子 3（Stat3）是调节细胞增殖和凋亡的重要转录因子。在这里，我们使用实时单细胞分析和 Western blot 分析，研究了 HF-LPLI（633nm，80 和 120J·cm(-2))对 COS-7 细胞中 Stat3 活性的变化及其涉及的潜在机制。我们发现 Stat3 被 HF-LPLI 以时间和剂量依赖的方式显著激活。Stat3 的激活减弱了 HF-LPLI 诱导的细胞凋亡，这表现在显性失活 Stat3（Y705F）和 Stat3 小干扰 RNA 表达增强了 HF-LPLI 诱导的细胞凋亡。此外，我们还发现Src 激酶是 HF-LPLI 诱导的 Stat3 激活的主要正调控因子。ROS 的产生对于 HF-LPLI 诱导的 Stat3 和 Src 激活是必需的，因为维生素 C 或 N-乙酰半胱氨酸清除 ROS 完全阻断了 Stat3 和 Src 的激活。总之，这些发现表明 ROS-Src-Stat3 通路介导了 HF-LPLI 诱导的 COS-7 细胞凋亡的负反馈抑制。我们的研究将为 HF-LPLI 诱导的细胞凋亡的机制提供新的见解，并扩展 Stat3 的功能研究。
