TET2/Sp4/Arl4D通路在电离辐射诱导神经发生障碍中的作用与机制研究

放射性认知功能障碍严重影响头颈部肿瘤患者的放疗疗效和生活质量。神经发生抑制是关键发病机制之一，其中DNA 5hmc修饰异常起重要作用。我们前期实验表明，受照小鼠海马的5hmC修饰和催化酶TET2减少，上调TET2改善神经发生抑制。TET2通过转录因子Sp4介导Arl4D的5hmc修饰是潜在分子机制。由此我们推测：TET2可以结合Sp4，上调Arl4D的5hmc修饰与表达，改善电离辐射诱导的神经发生障碍。为验证该假说，本项目将利用TET2基因敲除小鼠和神经干细胞，采用Western Blot、荧光素酶报告基因等手段阐明电离辐射后TET2/Sp4/Arl4D通路的信号转导机制，其次利用免疫荧光、Morris水迷宫等手段，在体内和体外水平，揭示TET2/Sp4/Arl4D通路对放射性认知功能障碍和神经发生障碍的影响。本项目将为深入了解放射性认知功能障碍的机制提供新思路，可能在短期内取得新的突破。

Radiation-induced cognitive dysfunction seriously impacts the curative results and quality of life in the brain and head-neck cancer patients treated by radiotherapy. The abnormalities of hippocampal neurogenesis have been identified as the most important change of the pathogenesis, but the underlying mechanisms are not understood fully up to now. The epigenetic modifications have proved important effect within different cells and tissues (organs) radiation injury. Canonical modification models, including DNA methylation, histone modification and chromatin remodeling, have been certified the development and maintenance of neurological function at the meantime. Among them, the DNA modification hydroxymethylation (5hmc) influences DNA transcription and cell-type-specific developmental programming and were abundant in the brain diseases. Because of the high expression in hippocampus and association with neurogenesis and cognitive function, the DNA 5hmc modification has gained increasing attention recently. Our preliminary results showed that A single dose of irradiation (10Gy) induced significant decrease of 5hmc and demethyltransferase TET2 in hippocampus. The elevation of TET2 protein relieved neurogenesis deficits. TET2/Sp4/Arl4D 5hmc signal pathway may be the potential mechanism. Therefore, our presented hypothesis is that served as an important epigenetic regulation effect, the complex TET2/Sp4-mediated ARL4D 5hmc modification modulates dynamic neurogenesis inhibition induced by ionizing radiation. By using the established mice model both radiation-induced cognitive injury and TET2 conditional knock-out, and utilization the associated techniques, such as the PCR, Western blot, DNA 5hmc measurements, and immunoprecipitation, immunofluorescence et al, we will explore the exact mechanism and role of TET2/Sp4-mediated ARL4D 5hmc modification in neurogenesis regulation, both in vitro and in vivo. It will be helpful in finding new clue of the prevention and treatment for radiation-induced cognitive dysfunction at last.