Structure, Function and Mechanistic Analysis of LAG3

LAG3(CD233)是一种抑制性受体，在控制T细胞耐受、预防 自身免疫和限制免疫介导的组织损伤。它在耗尽的T细胞上高度上调 在肿瘤和慢性病毒感染中，限制了无菌免疫的发展。因此，LAG3是 现在是治疗癌症和其他疾病的主要免疫治疗靶点，进行了多项临床试验 正在进行中。尽管对LAG3进行了30多年的广泛分析，并在 临床上，对LAG3的作用机制以及如何开发最佳的LAG3知之甚少。 靶向治疗药物，尤其是激动剂。虽然假设主要的，也许只是在功能上 LAG3的相关配体是MHC类II，有几个观察结果，包括我们最近的初步研究 这表明，LAG3发挥作用还有额外的生物物理要求。 目的1：定义和比较LAG3与其配体的相互作用。我们将回答3个问题：(A) 结构域和残基介导LAG3与其配体的相互作用？(B)LAG3与其配体的结合能否 会被不同的抗LAG3抗体干扰吗？(C)哪些LAG3残基介导配体相互作用？ 目的2：确定LAG3及LAG3：AB和LAG3：MHC-II类配合物的晶体结构。我们会 通过提出3个问题阐述LAG3生物学功能的结构基础：(A)什么独特的结构 LAG3的特性使其有别于CD4？(B)LaG3：AB络合物的结构是什么？(C)什么是 LaG3的结构：MHC II类复合体？ 目的3：确定LAG3与其配体相互作用的功能影响。我们将回答3个问题： (A)LAG3是否需要与其各种配体结合才能发挥作用？(B)法律顾问小组3与其 在肿瘤模型中，不同的配体对其功能有不同的影响？(C)正在阻止LAG3的关联 与其不同的配体有不同的治疗效益吗？ 该项目将对我们理解LAG3的作用机制产生重大影响，因为 并提供了对增强型治疗试剂的产生的进一步洞察，这些增强型治疗试剂阻止或 增强LAG3功能。鉴于我们已经确定了LAG3在调节和效应上的功能 T细胞功能，研究LAG3功能已有~19年之久，为我们提供了多种独特的 探索其功能的工具，并组建了一个强大的、技术多样化的协作团队，我们 是进行这项研究的最佳人选。

LAG3 (CD233) is an inhibitory receptor that plays a critical role in controlling T cell tolerance, preventing autoimmunity and limiting immune-mediated tissue damage. It is highly upregulated on exhausted T cells in tumors and in chronic viral infections, limiting the development of sterilizing immunity. Consequently, LAG3 is now a major immunotherapeutic target for the treatment of cancer and other diseases, with multiple clinical trials ongoing. Despite extensive analysis of LAG3 for over 30 years and multiple LAG3 targeting therapeutics in the clinic, very little is known about the mechanism of action of LAG3 and thus how to develop optimal LAG3- targeting therapeutics, especially agonists. While it is assumed that the primary and perhaps only functionally relevant ligand for LAG3 is MHC class II, there are several observations including our recent preliminary studies that suggest that there are additional biophysical requirements for LAG3 to function. AIM 1: Define and compare LAG3 interaction with its ligands. We will address 3 questions: (A) Which domains and residues mediate LAG3 interaction with its ligands? (B) Can the association of LAG3 with its ligands be disrupted by different anti-LAG3 Abs? (C) What LAG3 residues mediate ligand interaction? AIM 2: Determine crystal structures of LAG3 and of LAG3:Ab and LAG3:MHC class II complexes. We will address the structural basis for the biological function of LAG3 by asking 3 questions: (A) What unique structural features of LAG3 distinguish it from CD4? (B) What is the structure of LAG3:Ab complexes? (C) What is the structure of LAG3:MHC class II complexes? AIM 3: Determine the functional impact of LAG3 interaction with its ligands. We will address 3 questions: (A) Is LAG3 association with its various ligands required for its function? (B) Does LAG3 interaction with its various ligands have a differential impact on its function in tumor models? (C) Is blocking the association of LAG3 with its different ligands have differential therapeutic benefit? This project will have a significant impact on our understanding of the mechanism of action of LAG3, as well as provide further insight into the generation of enhanced therapeutic reagents that block or enhance LAG3 function. Given that we have determined the function of LAG3 on regulatory and effector T cell function, have been studying LAG3 function of ~19 years, have available to us a variety of unique tools to probe its function and have assembled a strong and technically diverse collaborative team, we are in the best position to conduct this research.