自噬引起纳米银细胞毒性的作用机制

纳米银在兽医领域具有广泛的应用潜力，但较强的毒性极大地限制了其临床应用。因此，如何降低纳米银细胞毒性提高其临床应用价值是纳米银研究领域的焦点。最新研究发现自噬参与纳米银细胞毒性的调控，但其确切机制尚不清楚。我们前期研究证实聚乙烯吡咯烷酮包覆的纳米银通过促进活性氧（ROS）产生和银离子（Ag+）释放抑制Ba/F3细胞活性，并发现纳米银能够剂量依赖性诱导细胞发生自噬产生毒性，但通过3-甲基腺嘌呤抑制自噬能有效降低纳米银诱导的细胞凋亡和DNA损伤。基于此基础，本项目将借助维生素C和N-乙酰半胱氨酸的干预揭示ROS和Ag+在纳米银诱发Ba/F3细胞自噬中的作用；通过研究纳米银对自噬信号通路和自噬流的影响阐明自噬的诱发机制；并采用RNA干扰技术降低自噬水平探明自噬调控细胞凋亡的分子机制。本项目渴望从自噬角度阐明纳米银毒性产生机制，并为探索基于干预自噬降低纳米银毒性的策略提供理论依据。

Silver nanoparticles (AgNPs) have a wide range of potential applications in veterinary field, but the relatively strong toxicity is the main reason to restrict its clinical use. Now quite a few researches are focused on revealing the cytotoxic mechanism of AgNPs. It has been appreciated that autophagy is involved in regulating the cytotoxicity of AgNPs, however, how AgNPs induce autophagy mediating cytotoxicity remains incompletely understood. Our preliminary data demonstrated that PVP-coated AgNPs inhibited the viability of Ba/F3 cells by promoting the generation of reactive oxygen species (ROS) and release of silver ions (Ag+), thus induced autophagy in a dose-dependent manner and exerted toxic effect, while 3-methyladenine could effectively reverse the apoptosis and DNA damage triggered by AgNPs. Thus we hypothesize that AgNPs induce autophagy and consequently mediate cytotoxicity, and reversing the autophagy is a novel intervention strategy for reducing the toxicity caused by AgNPs. This study intends to investigate the following scientific questions: 1) the role of ROS and Ag+ in AgNPs-induced autophagy; 2) the effect of AgNPs on autophagic signaling pathway and flux; 3) the molecular mechanism of the crosstalk between autophagy and apoptosis. The study will manifest how autophagy regulates apoptosis and shed lights on how to design a novel intervention strategy for reversing the AgNPs-mediated cytotoxicity.