Chemokine CXCL1 Dimer Is a Potent Agonist for the CXCR2 Receptor
Chemokine CXCL1 Dimer Is a Potent Agonist for the CXCR2 Receptor
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DOI：
10.1074/jbc.m112.443762
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发表时间：
2013-04-26
影响因子：
4.8
通讯作者：
Rajarathnam, Krishna
中科院分区：
文献类型：
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作者：
Ravindran, Aishwarya;Sawant, Kirti V.;Rajarathnam, Krishna
CXCL 1/CXCR 2轴在响应微生物感染和组织损伤而募集中性粒细胞中起着至关重要的作用，并且该过程中的功能障碍与各种炎性疾病有关。趋化因子以单体和二聚体的形式存在，现在有令人信服的证据表明这两种形式都调节体内功能。因此，了解CXCL 1单体和二聚体的受体活性对于描述它们协调中性粒细胞功能的分子机制是至关重要的。单体-二聚体平衡常数（类似于20 μ M）和CXCR 2结合常数（1 nM）表明WT CXCL 1作为单体具有活性。为了表征二聚体活性，我们通过在二聚体界面上引入二硫化物来产生捕获的二聚体。这种二硫键连接的CXCL 1二聚体以纳摩尔亲和力结合CXCR 2，并在各种细胞测定中显示出有效的激动剂活性。我们还比较了这种二聚体与CXCL 1单体的受体结合机制，通过删除稳定二聚体界面的C-末端残基产生。我们观察到二聚体和单体与CXCR 2 N-末端结构域的结合相互作用基本上是保守的，该结构域在确定亲和力和活性中起重要作用。CXCL 1二聚体的有效活性是新的：CC趋化因子CCL 2和CCL 4的二聚体是无活性的，CXC趋化因子CXCL 8的二聚体（与CXCL 1密切相关）对CXCR 1有轻微活性，但对CXCR 2显示可变活性。我们的结论是，不同的趋化因子受体对之间的二聚体活性的巨大差异已经演变为微调白细胞功能。
The CXCL1/CXCR2 axis plays a crucial role in recruiting neutrophils in response to microbial infection and tissue injury, and dysfunction in this process has been implicated in various inflammatory diseases. Chemokines exist as monomers and dimers, and compelling evidence now exists that both forms regulate in vivo function. Therefore, knowledge of the receptor activities of both CXCL1 monomer and dimer is essential to describe the molecular mechanisms by which they orchestrate neutrophil function. The monomer-dimer equilibrium constant (similar to 20 mu M) and the CXCR2 binding constant (1 nM) indicate that WT CXCL1 is active as a monomer. To characterize dimer activity, we generated a trapped dimer by introducing a disulfide across the dimer interface. This disulfide-linked CXCL1 dimer binds CXCR2 with nanomolar affinity and shows potent agonist activity in various cellular assays. We also compared the receptor binding mechanism of this dimer with that of a CXCL1 monomer, generated by deleting the C-terminal residues that stabilize the dimer interface. We observe that the binding interactions of the dimer and monomer to the CXCR2 N-terminal domain, which plays an important role in determining affinity and activity, are essentially conserved. The potent activity of the CXCL1 dimer is novel: dimers of the CC chemokines CCL2 and CCL4 are inactive, and the dimer of the CXC chemokine CXCL8 (which is closely related to CXCL1) is marginally active for CXCR1 but shows variable activity for CXCR2. We conclude that large differences in dimer activity among different chemokine-receptor pairs have evolved for fine-tuned leukocyte function.