前期研究从系列化合物中发现FC9具有选择性抑制IFN-γ信号的独特作用，初步证实其靶蛋白是IFN-γR，为第1个IFN-γR的小分子抑制剂。本项目拟用多种方法确定FC9与IFN-γR的结合，在此基础上考察FC9对IFN-γ信号的抑制作用强度、选择性及调控IFN-γ/IFN-γR/STAT1通路的环节。进一步用SPR、ITC等手段证实FC系列化合物与IFN-γR胞外区结合的构效关系，借助计算机模拟、肽段截短法和点突变法等确定FC9与IFN-γR的结合位点；探讨FC9导致IFN-γR内吞后的细胞分子过程，利用核磁共振法、圆二色谱法和原子力显微镜等探讨并揭示FC9与IFN-γR的结合及结合后受体构象改变等化学基础。最后，比较野生型和IFN-γR敲除小鼠FC9对于相关免疫性疾病模型药效的差异，探讨新型IFN-γR抑制剂对于治疗T细胞相关免疫性疾病的意义，为这些难治性疾病提供合适的药物作用靶标

Our previous study has found the small compound FC9 from FC analogs with a selective inhibition on IFN-γ signaling. The target protein of FC9 is proved to be IFN-γR in preliminary experiments. This is the first small molecule inhibitor of IFN-γR. In the present study, we will confirm the binding of FC9 to IFN-γR by SPR or ITC assays and examine the characteristics of FC9 against IFN-γ signaling including the intensity, selectivity and underlying mechanisms. Then, we will examine the structural properties of FC9 analogs to bind to the extracellular domain of IFN-γR, and characterize the binding sites by using computer docking, truncated peptides, and amino acid mutations. We also want to explore the process of IFN-γR internalization and endocytosis and to determine the changes in protein conformation by NMR, circular dichroism spectra and atomic force microscope. Finally, we will compare the effects of FC9 on the related immune disease models in wild type and IFN-γR knock out mice and give a new insight for this novel IFN-γR inhibitor to the therapy of immune diseases.