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蛋白偶联的趋化因子受体CXCR4和非典型趋化因子受体ACKR3发挥着关键 通过对A 共享配体，CXCL12。两种受体都会导致多种炎症和自身免疫性疾病，并且是 在积极投资作为治疗目标下。但是，目前只有一个FDA批准 CXCR4拮抗剂（AMD3100/plerixafor），其使用仅限于动员造血干细胞的骨骼 骨髓移植，因为其许多特性是次优的。 ACKR3的治疗靶向较少 比CXCR4成熟阶段；实际上，大多数已知的化合物是激动剂，目前尚不清楚如何对抗 这个接收器。因此，需要改进靶向CXCR4和ACKR3的化合物。 作为“非典型”受体，ACKR3被广泛假定仅通过β-arrestin（而不是G蛋白）发挥作用，而不是G蛋白（而不是G蛋白） 以其从细胞外环境中“清除” CXCL12的能力而闻名。通过这样做，ACKR3 防止CXCR4的下调，并保持其对CXCL12梯度的响应能力。共表达时 在同一细胞中，ACKR3还可以通过异二聚化改变CXCR4信号传导和运输 β-arrestin和其他尚未获得的机制。鉴于ACKR3在体系结构中绑定CXCL12 与CXCR4相似，激活时经历了类似的构象变化，并共享所有保守的 G蛋白偶联的确定剂，其预览的GI无能力令人震惊。更加惊人的是非凡的 ACKR3激活配体和受体修饰的鲁棒性，而CXCR4激活被废除 按照此类更改的最微妙。由于这种激活的性质，大多数非化学因素（甚至很小） 分子）配体激活ACKR3与β-甲蛋白的关联，下游后果未知。 尽管两种受体在疾病中的作用，但它们的结构和分子机制是它们的基础 在此MPI建议中，Handel和Kufareva 实验室分别结合了他们的实验和计算专业知识，并深入了解 趋化因子受体，以解释CXCR4（AIM 1）和ACKR3（AIM 2）的不同激活机制 结构和动力学的角度，了解如何抑制这些受体（目标1和2），以及 了解ACKR3如何调节CXCR4的功能（AIM 3）。为了实现这些目标，特定的机械 通过结构性（冷冻EM和晶体学），计算（建模）结合探测假设 和MD）和基于细胞的功能实验，并通过无偏见的发现蛋白质组学完成。这些 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 关于小分子疗法的发展，并提供了阻断一个或两个受体的理由。 通过揭示一般原则，拟议的研究还将提高对其他的理解和靶向 在治疗上重要的趋化因子受体，被认为是挑战靶标。