Structure of the Chemokine Receptor CXCR3

描述(申请人提供)：G蛋白偶联受体(GPCRs)在人类健康和疾病中具有多种功能。FDA批准的药物中约有30%针对这些类型的受体。趋化因子受体属于GPCRs的一个亚家族，被8 kDa的小蛋白激活，参与体内平衡和免疫应答。CXCR3是20种趋化因子受体之一，由CXCL9、10和11三种趋化因子激活，参与向炎症组织募集CD4+1型辅助细胞(Th1)或CD8+细胞毒T细胞，以启动适当的免疫反应。这三种趋化因子是不同调节的，因此，尽管它们在细胞研究中竞争与CXCR3结合，但在体内并没有多余的作用。这些趋化因子和CXCR3还与各种自身免疫性疾病、移植排斥反应和移植物抗宿主病、特定感染和癌症有关。因此，这些趋化因子和CXCR3是许多疾病的有吸引力的治疗靶点。一种化合物(AMG487)未能通过牛皮癣的II期临床试验，可能是因为它在体内的代谢。这一应用的主要目的是利用CXCR3与小分子拮抗剂复合的结构生物学，为设计其他具有最佳治疗性能的拮抗剂提供基础。我们还对一个更基本的问题感兴趣：趋化因子如何结合它们的受体？寻找这个问题的答案超出了这个建议的范围，但基于先前纯化稳定的趋化因子-受体复合体的经验，我们打算探索在巴斯德毕赤酵母中创建一个克隆，表达CXCR3、其每个趋化因子激动剂和另外两个蛋白质，从而增加CXCR3和它的每个趋化因子激动剂之间的亲和力和稳定性。

DESCRIPTION (provided by applicant): G-protein coupled receptors (GPCRs) have many functions in human health and disease. About 30% of FDA approved drugs target these types of receptors. Chemokine receptors belong to a subfamily of GPCRs, are activated by small proteins of 8 kDa, and are involved in homeostasis and the immune response. CXCR3 is one of 20 chemokine receptors, is activated by three chemokines, CXCL9, 10, and 11, and is involved in recruiting CD4+ type-1 helper (Th1) or CD8+ cytotoxic T-cells to inflammatory tissues to initiate an appropriate immune response. These three chemokines are differentially regulated and, therefore, do not have redundant roles in vivo although they compete for binding to CXCR3 in cellular studies. These chemokines and CXCR3 are also involved in various autoimmune diseases, transplant rejection and graft versus host disease, specific infections, and cancer. Therefore, these chemokines and CXCR3 are attractive therapeutic targets for a number of diseases. One compound (AMG487) failed Phase II clinical trials for psoriasis, presumably due to its in vivo metabolism. The main goal in this application is to use structural biology of CXCR3 complexed to a small molecule antagonist to provide the foundation for the design of other antagonists with the optimum properties for a therapeutic. We are also interested in a more fundamental question: how do chemokines bind their receptors? Finding an answer to this question is beyond the scope of this proposal, but based on previous experience to purify a stable chemokine-receptor complex, we intend to explore creating a clone in P. pastoris expressing CXCR3, each of its chemokine agonists, and two other proteins that result in increased the affinity and stability between CXCR3 and each of its chemokine agonists.