肿瘤坏死因子超家族TL1A-DR3通路的结构基础

TNF superfamily receptors are one of those most important cell surface receptors, and they play key roles in immune activation, immune regulation, cell development and differentiation. TL1A（TNF-α like protein 1A）and DR3（death receptor 3) is an important TNF superfamily ligand and receptor pair. The excessive activation of this pathway is close related to several autoimmune disorders including rheumatoid arthritis, which makes DR3 pathway a potential drug target. Due to the absence of structural information of some major signaling complexes, the understanding of TL1A-DR3 pathway is limited. In our preliminary studies, we have determined the crystal structure of human TL1A. In this proposed project, we aim to address the following key questions: 1) Determine the unknown structure of some key complexes including TL1A: DR3 complex and DR3: TRADD complex. 2) Investigate the conformational change of the intracellular domain of DR3. 3) Screen and characterize high affinity nanobody against the intracellular and extracellular domain of DR3. This project will provide strong experimental evidence for the deep understanding of the trans-membrane signal transduction of TNF family receptors including the TL1A-DR3 pathways. Furthermore, the discovery and validation of novel drug target provides theoretical basis for development of blocking antibodies.

TNF家族受体是最重要的细胞表面受体之一，在免疫活化、免疫调节和发育分化等方面发挥着重要作用。TL1A和DR3是TNF家族中一对重要的配体-受体成员。该通路的过度活化与多种自身免疫病如风湿性关节炎等密切相关，因此DR3通路是一个潜在药物靶点。但是由于缺少关键信号复合物的结构信息，目前对TL1A-DR3信号通路还缺少分子层面的认识。我们已经解析了人TL1A的晶体结构，本项目希望对几个关键问题进行深入研究： 1）解析该通路中尚无结构的几个关键复合物的晶体结构，包括DR3胞外区与TL1A复合物及DR3胞内区与TRADD的复合物；2）深入探究DR3胞内区的构象变化；3）筛选并表征针对DR3胞外区和胞内区的高亲和力纳米抗体。本项目将为深入了解以TL1A-DR3通路为代表的TNF家族受体通路跨膜信号转导的分子机制，提供强有力的实验证据。通过发现和验证关键靶点，为研发药用价值的阻断抗体提供理论基础。

DR3作为TNF超级家族的成员，其过度活化可导致包括风湿性关节炎在内的多种自身免疫病。在本项目中，通过解析DR3胞内区的两种构象，并通过突变和细胞实验验证构象变化对于DR3信号通路的关键作用。DR3在信号传递过程中其胞内的DD结构域蛋白质折叠构象变化的发现，为深入了解和验证以TL1A-DR3通路为代表的TNF家族受体通路跨膜信号转导过程中发生的构象变化，提供了强有力的实验证据。此外，利用实验室建立的噬菌体展示平台筛选获得了几株针对DR3胞外区的高亲和力纳米抗体，为阻断药物设计与发现关键靶点表位，和开发有潜在药用价值的纳米抗体候选药物提供了理论依据。