人源程序性死亡受体PD-1与其配体PD-L2负性调控免疫应答的结构基础研究

Cancer accounts for 8 million death every year, about one in six of all global deaths. Most proportion of patients of cancer is diagnosed at the late stage, resulting in almost 100% mortality rates. The crucial roles of the PD-1/PD-L2 pathway in cancer immunology and relevant drug developments have been well addressed. Blockade of PD-1/PD-L2 could stimulate T cell responses to tumor microenvironment and treat effectively cancer by enhancing immunity, improving survival profiles and acquiring high response rates in several solid tumors. However, the molecular mechanisms of PD-1/PD-L2 negatively regulating immune responses remain to be elucidated. On the basis of our previous works, we will determine the solution structures and the dynamics of human PD-L2 (hPD-L2) protein and its complex with human PD-1 (hPD-1) by a combination of several biophysical techniques such as multi-dimensional heteronuclear NMR spectroscopy. Moreover, we will investigate the interactions between hPD-L2 and hPD-1 to determine the binding sites, affinities and mechanisms. Further, we will address the alterations of conformations and dynamic characteristics in hPD-L2 and hPD-1, which are induced by the complex formation. Our results will provide the structure basis for well understanding the crucial roles of hPD-1 and hPD-L2 in negatively regulating immune responses, and also lay the foundation for the developments of antibody drugs and new chemical scaffolds drugs based on the PD-1/PD-L2 pathway.

全球癌症死亡人数占总死亡人数的近六分之一，每年有800万人死于癌症。许多癌症病例在癌症晚期才得到诊断，死亡率几乎达到100%。PD-1/PD-L2信号通路是目前备受瞩目、广为研究的抗癌靶点之一，可充分利用人体自身的免疫系统抵御、抗击癌症，具有治疗多种类型肿瘤的潜力。然而，PD-1/PD-L2信号通路负性调控免疫应答的分子机制尚未清楚。本项目拟在前期工作的基础上，采用异核多维核磁共振等生物物理技术，测定人源PD-L2 (hPD-L2)蛋白和复合物hPD-1-hPD-L2的溶液结构和动力学特性，研究hPD-1与hPD-L2相互作用，比较hPD-1与hPD-L2自由态与复合物态的结构和动力学特性差异。研究结果将揭示hPD-1/hPD-L2信号通路负性调控免疫应答的结构基础和分子机制，并为研发基于hPD-1/hPD-L2信号通路的特异性抗体药物和小分子药物提供理论依据。

全球癌症死亡人数占总死亡人数的近六分之一，每年有800万人死于癌症。许多癌症病例在癌症晚期才得到诊断，死亡率几乎达到100%。PD-1/PD-L2信号通路是目前备受瞩目、广为研究的抗癌靶点之一，可充分利用人体自身的免疫系统抵御、抗击癌症，具有治疗多种类型肿瘤的潜力。本项目在执行期间，根据项目申请书中的研究内容，采用异核多维核磁共振技术为主要研究手段，结合其他生物化学和生物物理技术开展hPD-L2和hPD-1-hPD-L2的结构研究。通过本项目，我们研究了hPD-1与hPD-L2蛋白的相互作用，结果表明：二者具有中等偏弱的结合；制备了hPD-1与hPD-L2的单克隆抗体，并且hPD-1的单克隆抗体已应用于肿瘤的精准诊断和预后评判；筛选并获得了靶向hPD-L1的三个潜在的小分子药物。根据以上实验结果，我们基本上完成了项目申请书的研究计划。除此之外，我们开发了均相低剂量高效高灵敏度的检测核外hPD-L1的方法，可用于癌症的诊断和免疫疗法的预测。在本项目的资助下，我们对结核分枝杆菌反式翻译过程的SmpB蛋白和EF-Tu蛋白的结构进行研究，为新型小分子药物的研发奠定基础。

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