It's a tug of war: structure, consequences, and inhibition of CXCR4 and ACKR3 responses to lymphocyte chemoattractant CXCL12

这是一场拉锯战：CXCR4 和 ACKR3 对淋巴细胞趋化剂 CXCL12 反应的结构、后果和抑制

• 批准号: 10597645
• 负责人: Tracy M Handel
• 金额: $ 67.16万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-15 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10597645
• 关键词: AMD3100; Acceleration; Affect; Agonist; Architecture; Autoimmune Diseases; Binding; Biochemical; Biological Assay; Biotinylation; Bone Marrow Stem Cell Transplantation; CXCR4 Receptors; CXCR4 gene; Cells; Chemotactic Factors; Clinical Research; Complement; Complex; Coupled; Coupling; Cryoelectron Microscopy; Crystallography; Development; Disease; Down-Regulation; Drug Targeting; Environment; FDA approved; G-Protein-Coupled Receptors; GTP-Binding Proteins; Goals; Hematological Disease; Hematopoietic stem cells; Heterodimerization; Homing; Immune response; Immunologic Surveillance; Individual; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Investigation; Knowledge; Letters; Ligands; Lymphocyte; Maps; Mass Spectrum Analysis; Mediating; Modeling; Modification; Molecular; Molecular Conformation; Multiple Sclerosis; Mutagenesis; Nature; Pattern; Pharmacology; Play; Preparation; Property; Proteomics; Receptor Inhibition; Regulation; Resolution; Rest; Rheumatoid Arthritis; Roentgen Rays; Role; Signal Transduction; Stromal Cell-Derived Factor 1; Structure; Techniques; Therapeutic; Translating; War; Work; X-Ray Crystallography; antagonist; beta-arrestin; cell motility; chemokine; chemokine receptor; complement C2a; drug discovery; experimental study; extracellular; idiopathic pulmonary fibrosis; improved; insight; migration; molecular dynamics; molecular modeling; novel; organ growth; preclinical study; prevent; receptor; response; small molecule; small molecule therapeutics; spatiotemporal; targeted treatment; therapeutic target; trafficking; uptake

The G protein-coupled chemokine receptor, CXCR4, and the atypical chemokine receptor, ACKR3, play critical roles in cell migration during immune responses and organ development, through coordinated responses to a shared ligand, CXCL12. Both receptors contribute to numerous inflammatory and autoimmune diseases and are under active investigation as therapeutic targets. Nevertheless, there is currently only one FDA-approved CXCR4 antagonist (AMD3100/Plerixafor), and its use is limited to mobilizing hematopoietic stem cells for bone marrow transplants, because many of its properties are suboptimal. Therapeutic targeting of ACKR3 is at a less mature stage than CXCR4; in fact, most known compounds are agonists, and it is unclear how to antagonize this receptor. Improved compounds targeting both CXCR4 and ACKR3 are therefore needed. As an "atypical" receptor, ACKR3 is widely assumed to function only through β-arrestin (and not G proteins), and is best known for its ability to “scavenge” CXCL12 from the extracellular environment. By doing so, ACKR3 prevents downregulation of CXCR4 and maintains its responsiveness to CXCL12 gradients. When co-expressed in the same cell, ACKR3 can also alter CXCR4 signaling and trafficking via heterodimerization, sequestration of β-arrestin, and other as-yet-undeciphered mechanisms. Given that ACKR3 binds CXCL12 in an architecture similar to CXCR4, undergoes similar conformational changes upon activation, and shares all of the conserved G protein-coupling determinants, its presumed Gi incompetency is striking. Even more striking is the exceptional robustness of ACKR3 activation to ligand and receptor modifications, whereas CXCR4 activation is abrogated by the subtlest of such changes. Because of this activation-prone nature, most non-chemokine (and even small molecule) ligands activate ACKR3 association with β-arrestin, with unknown downstream consequences. Despite the role of the two receptors in disease, the structural and molecular mechanisms underlying their individual functions and their cellular crosstalk remain elusive. In this MPI proposal, the Handel and Kufareva labs combine their experimental and computational expertise, respectively, with their in-depth knowledge of chemokine receptors, to explain the distinct activation mechanisms of CXCR4 (Aim 1) and ACKR3 (Aim 2) from the standpoint of structure and dynamics, to understand how to inhibit these receptors (Aims 1 and 2), and to understand how ACKR3 regulates the function of CXCR4 (Aim 3). To achieve these aims, specific mechanistic hypotheses are probed with a combination of structural (cryo-EM and crystallography), computational (modeling and MD) and cell-based functional experiments, and complemented by unbiased discovery proteomics. These studies will deliver unprecedented insight into the function of CXCR4 and ACKR3, which will have a direct impact on the development of small molecule therapeutics and provide the rationale for blocking one or both receptors. By revealing general principles, the proposed studies will also advance the understanding and targeting of other therapeutically important chemokine receptors, which are considered challenging targets.

G 蛋白偶联趋化因子受体 CXCR4 和非典型趋化因子受体 ACKR3 发挥着关键作用 通过协调反应，在免疫反应和器官发育过程中细胞迁移中发挥作用 共有配体 CXCL12，这两种受体都会导致多种炎症和自身免疫性疾病。 然而，目前只有一种药物已获得 FDA 批准。 CXCR4拮抗剂（AMD3100/Plerixafor），其用途仅限于动员造血干细胞用于骨 骨髓移植，因为 ACKR3 的许多特性并不理想。 比CXCR4还处于成熟阶段；事实上，大多数已知的化合物都是激动剂，目前还不清楚如何拮抗。 因此需要针对 CXCR4 和 ACKR3 的改进化合物。 作为一种“非典型”受体，人们普遍认为 ACKR3 仅通过 β-arrestin（而不是 G 蛋白）发挥作用，并且 ACKR3 以其从细胞外环境中“清除”CXCL12 的能力而闻名。 当共表达时，可防止 CXCR4 下调并保持其对 CXCL12 梯度的响应性。 在同一细胞中，ACKR3 还可以通过异二聚化、隔离来改变 CXCR4 信号传导和运输。 鉴于 ACKR3 在架构中结合 CXCL12，β-arrestin 和其他尚未破译的机制。 与 CXCR4 类似，在激活时经历类似的构象变化，并共享所有保守的 G 蛋白偶联决定因素，其假定的 Gi 无能是令人震惊的例外。 ACKR3 激活对配体和受体修饰的稳健性，而 CXCR4 激活被废除 由于这种易于激活的性质，大多数非趋化因子（甚至很小）都会受到这种变化的最微妙的影响。 分子）配体激活 ACKR3 与 β-arrestin 的结合，下游后果未知。 尽管这两种受体在疾病中发挥作用，但它们背后的结构和分子机制 在这个 MPI 提案中，Handel 和 Kufareva 仍然难以捉摸单个功能及其细胞串扰。 实验室分别将他们的实验和计算专业知识与他们对以下领域的深入了解相结合 趋化因子受体，解释 CXCR4（目标 1）和 ACKR3（目标 2）的不同激活机制 结构和动力学的立场，了解如何抑制这些受体（目标 1 和 2），并 了解 ACKR3 如何调节 CXCR4 的功能（目标 3）。 通过结构（冷冻电镜和晶体学）、计算（建模）的组合来探索假设 和医学博士）和基于细胞的功能实验，并辅以公正的发现蛋白质组学。 研究将对 CXCR4 和 ACKR3 的功能提供前所未有的见解，这将产生直接影响 关于小分子疗法的开发并提供阻断一种或两种受体的基本原理。 通过揭示一般原则，拟议的研究还将促进其他人的理解和瞄准 治疗上重要的趋化因子受体，被认为是具有挑战性的靶标。