Sulfotyrosine-guided discovery of small molecule chemokine inhibitors

描述（由申请人提供）：该项目的目标是开发一个用于发现小分子趋化因子抑制剂的创新平台。趋化因子主要通过结合和激活 G 蛋白偶联受体家族来指导细胞迁​​移，这些受体通过酪氨酸硫酸化进行翻译后修饰。趋化因子功能需要硫酸化，这表明受体磺基酪氨酸直接参与趋化因子配体的特异性结合。我们最近通过解析趋化因子 SDF1/CXCL12 与其受体 CXCR4 的含磺基酪氨酸片段之间的复合物的 NMR 结构，揭示了趋化因子家族中磺基酪氨酸识别的分子基础。 CXCR4 的 N 端胞外结构域包含三个潜在的硫酸化位点，每个磺基酪氨酸占据 CXC12 表面上的一个独特的裂缝。我们假设，由于磺基酪氨酸识别位点对于高亲和力受体结合至关重要，因此每个识别位点都代表使用针对趋化因子配体的小分子进行抑制的靶点。在具体目标 1 中，我们建议在 CXCL12 表面上定义额外的磺基酪氨酸识别位点，并结合使用高通量对接计算、通过 2D NMR 验证位点特异性配体结合以及测试趋化因子抑制的功能测定。我们将使用 CXCL12/CXCR4 复合物的结构作为测试用例来改进目标 2 中的计算机筛选方法，以评估灵活侧链对接和针对 NMR 构象异构体整体的片段筛选。将使用 SAR 分析并设计和合成结合来自相邻磺基酪氨酸识别位点的配体的新型化合物，对特定目标 3 中的亲和力和选择性进行命中到先导和先导优化。与 CXCL12 结合并在基于细胞的趋化因子测定中充当有效和选择性抑制剂的化合物将可供现有合作者用于动物临床前研究。为了评估磺基酪氨酸定向抑制的更广泛潜力，我们将开发一种简化的方法来识别特定目标 4 中的位点，并将我们的筛选方法应用于一组有代表性的趋化因子靶标。以磺基酪氨酸识别为指导的基于结构的药物发现是一项概念性的进步，可应用于趋化因子家族的所有 50 个成员以及需要这种蛋白质修饰才能在细胞外空间发挥作用的其他复合物。应用这一策略而产生的针对炎症和自身免疫性疾病或癌症的新疗法将对人类健康产生重大影响。

DESCRIPTION (provided by applicant): The goal of this project is the development of an innovative platform for discovery of small molecule chemokine inhibitors. Chemokines direct cell migration primarily by binding and activating a family of G protein-coupled receptors that are post-translationally modified by tyrosine sulfation. Sulfation is required for chemokine function, suggesting that receptor sulfotyrosines participate directly in specific binding of the chemokine ligand. We recently revealed the molecular basis for sulfotyrosine recognition in the chemokine family by solving the NMR structure of a complex between the chemokine SDF1/CXCL12 and a sulfotyrosine-containing fragment of its receptor CXCR4. The N-terminal extracellular domain of CXCR4 contains three potential sulfation sites, and each sulfotyrosine occupies a unique cleft on the CXC12 surface. We hypothesize that because sulfotyrosine recognition sites are essential for high affinity receptor binding, each one represents a target for inhibition using small molecules directed at the chemokine ligand. In specific aim 1 we propose to define additional sulfotyrosine recognition sites on the CXCL12 surface and use a combination of high-throughput docking calculations, validation of site-specific ligand binding by 2D NMR, and functional assays to test for chemokine inhibition. We will refine our in silico screening methods in aim 2 using the structure of the CXCL12/CXCR4 complex as a test case for evaluation of flexible side chain docking and fragment screening against the ensemble of NMR conformers. Hit-to-lead and lead optimization will be performed for affinity and selectivity in specific aim 3 using SAR analysis and by designing and synthesizing novel compounds that combine ligands from adjacent sulfotyrosine recognition sites. Compounds that bind CXCL12 and function as potent and selective inhibitors in cell-based chemokine assays will be made available to existing collaborators for preclinical studies in animals. To assess the broader potential of sulfotyrosine- directed inhibition, we will develop a streamlined approach to site identification in specific aim 4 and apply our screening method to a representative set of chemokine targets. Structure-based drug discovery guided by sulfotyrosine recognition is a conceptual advance that can be applied to all 50 members of the chemokine family and other complexes that require this protein modification to function in the extracellular space. New treatments for inflammatory and autoimmune disease or cancer that emerge from application of this strategy will have a major impact on human health.