SB265610 is an allosteric, inverse agonist at the human CXCR2 receptor
SB265610 is an allosteric, inverse agonist at the human CXCR2 receptor
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DOI：
10.1111/j.1476-5381.2009.00182.x
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发表时间：
2009-09-01
影响因子：
7.3
通讯作者：
Charlton, S. J.
中科院分区：
文献类型：
--
作者：
Bradley, M. E.;Bond, M. E.;Charlton, S. J.
背景和目的：在之前的几项研究中，C-X-C趋化因子受体（CXCR）2拮抗剂1-（2-溴苯基）-3-（7-氰基- 3h -苯并三唑-4-基）-尿素（SB265610）被描述为与内源性激动剂竞争性结合。这与许多其他趋化因子受体拮抗剂形成对比，其中拮抗机制已被描述为变构。实验方法：为了确定SB265610在趋化因子受体拮抗剂中是否具有独特的机制，除了趋化人中性粒细胞外，还采用放射配体和[S-35]-GTP γ S结合的方法研究了SB265610在CXCR2受体上的作用方式。关键结果：在平衡饱和结合研究中，SB265610抑制了[I-125]-白细胞介素-8 （[I-125]-IL-8）的最大结合，而不影响K-d。相比之下，IL-8无法阻止[H-3]-SB265610的结合。动力学结合实验表明，这不是不可逆或缓慢可逆结合的产物。在功能实验中，SB265610引起IL-8和生长相关癌基因α的浓度-反应曲线向右移动，但也降低了每种激动剂引起的最大反应。将这些数据拟合到一个可操作的变构三元配合物模型表明，一旦结合，SB265610完全阻断受体的激活。在该制剂中，SB265610也抑制了基底[S-35]-GTP γ S的结合。结论和意义：综上所述，这些数据表明SB265610作为CXCR2受体的变构逆激动剂，结合在与激动剂结合位点不同的区域，可能通过干扰G蛋白偶联来阻止受体激活。英国药理学杂志（2009）158,328-338；doi: 10.1111 / j.1476-5381.2009.00182.x;2009年4月27日在线发布
Background and purpose: In several previous studies, the C-X-C chemokine receptor (CXCR)2 antagonist 1-(2-bromo-phenyl)-3-(7-cyano-3H-benzotriazol-4-yl)-urea (SB265610) has been described as binding competitively with the endogenous agonist. This is in contrast to many other chemokine receptor antagonists, where the mechanism of antagonism has been described as allosteric.Experimental approach: To determine whether it displays a unique mechanism among the chemokine receptor antagonists, the mode of action of SB265610 was investigated at the CXCR2 receptor using radioligand and [S-35]-GTP gamma S binding approaches in addition to chemotaxis of human neutrophils.Key results: In equilibrium saturation binding studies, SB265610 depressed the maximal binding of [I-125]-interleukin-8 ([I-125]-IL-8) without affecting the K-d. In contrast, IL-8 was unable to prevent binding of [H-3]-SB265610. Kinetic binding experiments demonstrated that this was not an artefact of irreversible or slowly reversible binding. In functional experiments, SB265610 caused a rightward shift of the concentration-response curves to IL-8 and growth-related oncogene alpha, but also a reduction in maximal response elicited by each agonist. Fitting these data to an operational allosteric ternary complex model suggested that, once bound, SB265610 completely blocks receptor activation. SB265610 also inhibited basal [S-35]-GTP gamma S binding in this preparation.Conclusions and implications: Taken together, these data suggest that SB265610 behaves as an allosteric inverse agonist at the CXCR2 receptor, binding at a region distinct from the agonist binding site to prevent receptor activation, possibly by interfering with G protein coupling. British Journal of Pharmacology (2009) 158, 328-338; doi: 10.1111/j.1476-5381.2009.00182.x; published online 27 April 2009