Biasing CXCR3 Signaling to Modulate the Inflammatory Response

CXCR3是一种趋化因子受体(CKR)，通过调节T细胞在炎症中发挥重要作用 迁移和功能。尽管CKRs在疾病中的临床相关性已经确立，但只有三个FDA 已批准的针对整个趋化因子系统的药物，该系统由大约20个受体和 50种配体，几乎控制着炎症的方方面面。CKR药物开发困难的原因- 包括给定CKR的多个趋化因子配体之间的潜在冗余以及缺乏 了解由CKRs激活的信号通路如何调节免疫细胞功能和炎症。 因此，针对趋化因子系统的药物存在严重的未得到满足的需求。这将把工作放在背景下进行 我的团队研究趋化因子受体CXCR3。我们已经证明了CXCR3，CXCL9， 10和11作为有偏向的激动剂，彼此产生数量和质量上不同的信号 通过它们与异三聚体G蛋白和β-arrestin接头蛋白的相互作用。在上一个项目中 期间，我们已经确定了小分子G蛋白和β-arrestin偏向的CXCR3激动剂：(1)不同的 激活CXCR3下游的信号通路，以及(2)在T细胞小鼠模型中有明显的作用。 介导性炎症性皮肤病。这些发现提示G蛋白和β-arrestin在PRO中具有不同的作用。 激活CXCR3介导的炎症反应。我们研究的长期目标是确定 有偏见的激动症的潜在机制，以开发针对炎症中的CKRs的新疗法。整体而言 这项建议的目的是确定偏向CXCR3的激动剂如何促进不同的效应器构象 这会导致不同的信号模式，导致T细胞功能和炎症的变化。我们的中央 假设偏向β-arrestin的激动剂促进独特的受体和β-arrestin构象有利于 在T细胞和炎症中促进独特转录反应的“位置偏向”内体信号。 提顿。为了达到我们的目标，首先，我们将确定受体：配体复合体是如何促进有偏向的Re。 通过效应器的变构调节。我们发现偏向CXCR3的激动剂促进不同的 β-arrestin介导的效应，我们将使用受体突变体进一步探索这一效应。然后，我们将确定 内体信号和位置偏向如何影响CXCR3偏向信号转导。我们发现有些人 偏向CXCR3的激动剂促进转录，这可以通过抑制受体内吞来阻止。最后， 我们将确定CXCR3G蛋白和β-arrestin介导的信号通路如何影响T细胞功能 以及炎症反应。我们将使用CXCR3突变体来测试特定信号通路的贡献- T细胞体外趋化和体内炎症的途径。这个项目探索了一种创新的研究方法 CXCR3信号，将提供对CXCR3调节炎症反应的了解 选择性激活G蛋白和β阻滞素。这项研究具有重要意义，因为它将为 研究偏向激动剂作为针对CXCR3的治疗方法，并作为GPCRS药物设计的模型。

CXCR3 is a chemokine receptor (CKR) that plays a central role in inflammation through its regulation of T cell migration and function. Despite the established clinical relevance of CKRs in disease, there are only three FDA approved drugs that target the entire chemokine system, which consists of approximately twenty receptors and fifty ligands that regulate nearly every aspect of inflammation. Reasons for this difficulty in CKR drug develop- ment include the potential redundancy between multiple chemokine ligands for a given CKR and a lack of knowledge of how the signaling pathways activated by CKRs regulate immune cell function and inflammation. Thus, there is a critical unmet need for drugs targeting the chemokine system. This puts into context work from my group on the chemokine receptor CXCR3. We have shown that the chemokine ligands of CXCR3, CXCL9, 10 and 11, act as biased agonists, generating quantitatively and qualitatively distinct signals from one another through their interactions with heterotrimeric G proteins and β-arrestin adapter proteins. In the previous project period, we have identified small-molecule G protein- and β-arrestin-biased CXCR3 agonists that (1) differentially activate signaling pathways downstream of CXCR3, and (2) have distinct effects in a mouse model of T-cell- mediated inflammatory skin disease. These findings suggest distinct roles for G proteins and β-arrestin in pro- moting the CXCR3-mediated inflammatory response. The long-term goal of our research is to determine the mechanisms underlying biased agonism to develop novel therapies targeting CKRs in inflammation. The overall objective of this proposal is to determine how CXCR3 biased agonists promote different effector conformations that lead to distinct patterns of signaling resulting in changes in T cell function and inflammation. Our central hypothesis is that β-arrestin-biased agonists promote unique receptor and β-arrestin conformations that favor “location-biased” endosomal signaling that promotes a unique transcriptional response in T cells and inflamma- tion. To address our objective, first, we will determine how the receptor:ligand complex promotes biased re- sponses through allosteric regulation of effectors. We have found that CXCR3 biased agonists promote different β-arrestin-mediated effects, which we will explore further by using receptor mutants. Then, we will determine how endosomal signaling and location bias contribute to CXCR3 biased signaling. We have found that some CXCR3 biased agonists promote transcription that can be prevented by inhibiting receptor endocytosis. Lastly, we will determine how CXCR3 G protein- and β-arrestin-mediated signaling pathways contribute to T cell function and the inflammatory response. We will use CXCR3 mutants to test the contributions of specific signaling path- ways to T cell chemotaxis in vitro and inflammation in vivo. This project explores an innovative approach to study CXCR3 signaling that will provide an understanding of CXCR3 regulation of the inflammatory response by the selective activation of G proteins and β-arrestins. The research is significant as it will lay the groundwork for research on biased agonists as therapies targeting CXCR3 and serve as a model for drug design at GPCRs.