Positive allosteric modulation by ivermectin of human but not murine P2X7 receptors
Positive allosteric modulation by ivermectin of human but not murine P2X7 receptors
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DOI：
10.1111/j.1476-5381.2012.01987.x
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发表时间：
2012-09-01
影响因子：
7.3
通讯作者：
Schaefer, M.
中科院分区：
文献类型：
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作者：
Noerenberg, W.;Sobottka, H.;Schaefer, M.
在哺乳动物细胞中，抗寄生虫药物伊维菌素被认为是atp激活的离子通道P2X4的正变构调节剂，用于区分P2X4-和p2x7介导的细胞反应。在本文中，我们提供证据，报道伊维菌素的异构体选择性是一种物种特异性现象。实验方法采用电生理和荧光互补的方法评价伊维菌素对重组表达的P2X7受体和天然P2X7受体的影响。提供了离子电流和孔膨胀特性的生物物理特性。出乎意料的是，伊维菌素增强了内源性表达hP2X7受体的人单核细胞源性巨噬细胞中的电流。同样，在ATP浓度为亚最大值或饱和时，伊维菌素可增强电流和通过重组人（hP2X7）受体的[Ca2+]i内流。由于细胞内的伊维菌素没有模仿或阻止其活性，当应用于浴液时，伊维菌素在hP2X7受体上的结合位点似乎可以从细胞外侧进入。与通过P2X4受体的电流相比，伊维菌素没有引起ATP去除后hP2X7电流衰减的延迟。有趣的是，NMDG+通透性和Yo-Pro-1摄取不受伊维菌素的影响。在大鼠或小鼠P2X7受体上，伊维菌素的效果较差，表明其作用模式具有物种特异性。结论和意义这些数据表明，在人类细胞和组织中使用这种细胞生物学工具时，应考虑伊维菌素对人类P2X7受体的一种以前未被认识到的物种特异性调节。
BACKGROUND AND PURPOSE In mammalian cells, the anti-parasitic drug ivermectin is known as a positive allosteric modulator of the ATP-activated ion channel P2X4 and is used to discriminate between P2X4- and P2X7-mediated cellular responses. In this paper we provide evidence that the reported isoform selectivity of ivermectin is a species-specific phenomenon. EXPERIMENTAL APPROACH Complementary electrophysiological and fluorometric methods were applied to evaluate the effect of ivermectin on recombinantly expressed and on native P2X7 receptors. A biophysical characterization of ionic currents and of the pore dilation properties is provided. KEY RESULTS Unexpectedly, ivermectin potentiated currents in human monocyte-derived macrophages that endogenously express hP2X7 receptors. Likewise, currents and [Ca2+]i influx through recombinant human (hP2X7) receptors were potently enhanced by ivermectin at submaximal or saturating ATP concentrations. Since intracellular ivermectin did not mimic or prevent its activity when applied to the bath solution, the binding site of ivermectin on hP2X7 receptors appears to be accessible from the extracellular side. In contrast to currents through P2X4 receptors, ivermectin did not cause a delay in hP2X7 current decay upon ATP removal. Interestingly, NMDG+ permeability and Yo-Pro-1 uptake were not affected by ivermectin. On rat or mouse P2X7 receptors, ivermectin was only poorly effective, suggesting a species-specific mode of action. CONCLUSIONS AND IMPLICATIONS The data indicate a previously unrecognized species-specific modulation of human P2X7 receptors by ivermectin that should be considered when using this cell-biological tool in human cells and tissues.