Abstract：
Aquaporin 4 (AQP4) facilitates the transport of reactive oxygen species (ROS). Both cancer cells and the ionizing radiation microenvironment can induce posttranslational modifications (PTMs) in AQP4, which may affect its permeability to ROS. Because this ROS diffusion process is rapid, microscopic, and instantaneous within and outside cells, conventional experimental methods are inadequate for elucidating the molecular mechanisms involved. In this study, computational methods were employed to investigate the permeability of exogenous ROS mediated by radiation in AQP4 at a molecular scale. We constructed a simulation system incorporating AQP4 and AQP4-Cysp13 in a complex lipid environment with ROS. Long-timescale molecular dynamics simulations were conducted to assess the structural stability of both AQP4 and AQP4-Cysp13. Free energy calculations were utilized to determine the ROS transport capability of the two AQP4 proteins. Computational electrophysiology and channel structural analysis quantitatively evaluated changes in ROS transport capacity under various radiation-induced transmembrane voltage microenvironments. Our findings demonstrate the distinct transport capabilities of AQP4 channels for water molecules and various types of ROS and reveal a decrease in transport efficiency when AQP4 undergoes palmitoylation modification. In addition, we have simulated the radiation-induced alteration of cell membrane voltage, which significantly affected the ROS transport capacity. We propose that this research will enhance the understanding of the molecular mechanisms governing the transport of exogenous ROS by AQP4 and elucidate the influence of palmitoylation on ROS transport. This study will also help clarify how different structural features of AQP4 affect the transport of exogenous ROS mediated by radiotherapy, thereby providing a theoretical molecular basis for the development of new treatment strategies that combine with radiotherapy.
摘要：
水通道蛋白4(AQP4)促进活性氧(ROS)的转运。癌细胞和电离辐射微环境都可以诱导AQP4的翻译后修饰（PTM），这可能会影响其对ROS的渗透性。因为这种ROS扩散过程很快,微观,细胞内外的瞬时，传统的实验方法不足以阐明所涉及的分子机制。在这项研究中,采用计算方法在分子尺度上研究了辐射介导的外源ROS在AQP4中的通透性。我们在含有ROS的复杂脂质环境中构建了一个包含AQP4和AQP4-Cysp13的模拟系统。进行长时间分子动力学模拟以评估AQP4和AQP4-Cysp13的结构稳定性。利用自由能计算来确定两种AQP4蛋白的ROS转运能力。计算电生理学和通道结构分析定量评估了在各种辐射诱导的跨膜电压微环境下ROS传输能力的变化。我们的发现证明了AQP4通道对水分子和各种类型的ROS的独特转运能力，并揭示了当AQP4经历棕榈酰化修饰时转运效率的降低。此外,我们模拟了辐射引起的细胞膜电压变化，这显著影响了ROS的运输能力。我们建议这项研究将加强对AQP4控制外源ROS转运的分子机制的理解，并阐明棕榈酰化对ROS转运的影响。本研究还将有助于阐明AQP4的不同结构特征如何影响放疗介导的外源性ROS的转运。从而为开发AQPs与放疗相结合的新治疗策略提供了理论分子基础。
