The human CXC chemokine receptor 1 (CXCR1), a G protein-coupled receptor (GPCR), plays significant roles in inflammatory diseases and cancer. While CXCL8 is a well-established high-affinity ligand for CXCR1, there is no consensus regarding the binding ability of the other ELR+ chemokines (CXCL1-3 and CXCL5-8). Since research has predominantly focused on CXCL8-mediated CXCR1 signaling, insight into potential signaling bias induced by different CXCR1 ligands is lacking. Therefore, in this study we first compared and clarified the binding ability of all ELR+ chemokines using a competition binding assay. In this assay CXCL1-3 and CXCL5 behaved as low-affinity ligands while CXCL6-8 were high affinity ligands. We further investigated potential ligand bias within the CXCR1 signaling system. Using NanoBRET-based assays heterotrimeric G protein dissociation, β-arrestin recruitment and receptor internalization induced by chemokine binding to CXCR1 were investigated. A quantitative and qualitative investigation of ligand bias showed that the high-affinity ELR+ chemokines were biased towards G protein activation over β-arrestin recruitment and receptor internalization, when CXCL8 was used as a reference ligand.

中文翻译：

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高亲和力 ELR+ 趋化因子配体在 CXCR1 信号传导中显示 G 蛋白偏倚于 β-arrestin 募集和受体内化


人 CXC 趋化因子受体 1 （CXCR1） 是一种 G 蛋白偶联受体 （GPCR），在炎症性疾病和癌症中起着重要作用。虽然 CXCL8 是 CXCR1 的成熟高亲和力配体，但关于其他 ELR+ 趋化因子（CXCL1-3 和 CXCL5-8）的结合能力尚未达成共识。由于研究主要集中在 CXCL8 介导的 CXCR1 信号传导上，因此缺乏对不同 CXCR1 配体诱导的潜在信号转导偏差的见解。因此，在本研究中，我们首先使用竞争结合测定比较并阐明了所有 ELR + 趋化因子的结合能力。在该测定中，CXCL1-3 和 CXCL5 表现为低亲和力配体，而 CXCL6-8 是高亲和力配体。我们进一步研究了 CXCR1 信号系统中的潜在配体偏倚。使用基于 NanoBRET 的测定研究了趋化因子与 CXCR1 结合诱导的异源三聚体 G 蛋白解离、β-arrestin 募集和受体内化。配体偏倚的定量和定性研究表明，当 CXCL8 用作参考配体时，高亲和力 ELR+ 趋化因子偏向于 G 蛋白激活，而不是 β-arrestin 募集和受体内化。