Structure, pharmacology and signaling of G protein-coupled receptors (GPCRs) in inflammation

项目摘要 炎症是一个复杂的过程，涉及许多脂质和肽介质。大量的这些 介质通过对G蛋白偶联的作用引起促炎或促消退作用。 受体（GPCR）。我们的研究集中在一组GPCR作为密切的系统发育邻居， 包括促炎介质的受体，所述促炎介质包括过敏毒素、甲酰肽和 前列腺素D2（PGD 2）和新发现的专门促分解脂质介质（SPM），包括 脂氧素A4（LXA 4）和消退素。该GPCR家族的成员是开发新药的活性靶点 治疗各种炎症性疾病到目前为止，还没有关于这个家族的结构的报道。因此我们的 对配体作用、受体活化和信号传导的分子机制的理解是相当重要的。 这阻碍了药物的开发。为了填补这一知识空白，最近我们获得了晶体 该家族中的两个成员C5 a受体（C5 aR）和前列腺素D2受体2的结构 （CRTH2）。这两种结构提供了关于C5 aR拮抗作用的创新信息， CRTH 2.我们建议进一步确定不同药理作用的分子决定因素， C5 aR和CRTH 2拮抗剂通过测试基于我们的结构的新假设。我们将摄入蛋白质 晶体学和电子显微镜（EM）的方法并行获得高分辨率的结构， 与激动剂和Gi蛋白复合的活性C5 aR和CRTH 2。结果将揭示结构 激动剂结合和受体活化的基础。此外，我们建议开发小分子拮抗剂， 通过基于结构的药物设计（SBDD）方法为C5 aR和CRTH 2提供新的化学支架。我们 还将测试开发C5 aR和CRTH 2的细胞外构象抗体作为新的 阻断促炎信号通路的药理学工具。长期目标是朝着 C5 aR和CRTH 2新制剂的临床研究。另一个长期的研究方向是， 研究介导促消退信号通路以促进炎症消退的GPCR。FPR2/ALX （甲酰肽受体2/LXA 4受体）将是我们的主要研究目标。FPR 2/ALX可以被一种 许多结构上不相关的介质介导促炎或促消退反应。 对这种受体的研究旨在揭示不同配体作用的结构基础， 功能选择性的分子机制。我们的研究对健康意义重大，因为这些发现 将促进开发用于抗炎和促消退的创新药理学工具， 在治疗许多炎症性疾病的治疗策略。

Project Summary Inflammation is a complex process with many lipid and peptide mediators involved. A large number of these mediators elicit either pro-inflammatory or pro-resolving effects through the action on G protein-coupled receptors (GPCRs). Our research is focused on a group of GPCRs as close phylogenetic neighbors, which comprises receptors for the pro-inflammatory mediators including anaphylatoxins, formylpeptides and prostaglandin D2 (PGD2), and the newly discovered specialized pro-resolving lipid mediators (SPMs) including lipoxin A4 (LXA4) and resolvins. The members of this GPCR family are active targets for developing new drugs for a variety of inflammatory diseases. So far no structures have been reported for this family. Thus our understanding of the molecular mechanisms underlying ligand action, receptor activation and signaling is quite limited, which has impeded drug development. To fill this knowledge gap, recently we have obtained crystal structures of two members in this family, the C5a receptor (C5aR) and the prostaglandin D2 receptor 2 (CRTH2). These two structures provided innovative information regarding the antagonism of C5aR and CRTH2. We propose to further define the molecular determinants for the diverse pharmacological action of C5aR and CRTH2 antagonists by testing novel hypotheses based our structures. We will take protein crystallography and electron microscopy (EM) approaches in parallel to obtain high-resolution structures of active C5aR and CRTH2 in complex with agonists and the Gi protein. The results will reveal the structural basis of agonist binding and receptor activation. In addition, we propose to develop small-molecule antagonists with new chemical scaffolds for C5aR and CRTH2 through structure-based drug design (SBDD) approach. We will also test the possibility of developing extracellular conformational antibodies of C5aR and CRTH2 as new pharmacological tools to block pro-inflammatory signaling pathways. The long-term goal is to move towards the clinical investigation of such new agents for C5aR and CRTH2. Another long-term research direction is to study GPCRs that mediate pro-resolving signaling pathways to promote inflammation resolution. FPR2/ALX (formylpeptide receptor 2/LXA4 receptor) will be our primary research target. FPR2/ALX can be targeted by a number of structurally unrelated mediators to mediate either pro-inflammatory or pro-resolving responses. Research on this receptor is aimed to reveal the structural basis for the action of diverse ligands and the molecular mechanism for the functional selectivity. Our study is significant for health because the discoveries will facilitate the development of innovative pharmacological tools for both anti-inflammatory and pro-resolving therapeutic strategies in the treatment of many inflammatory diseases.