Inhibition of lysosomal degradation rescues pentamidine-mediated decreases of KIR2.1 ion channel expression but not that of Kv11.1
Inhibition of lysosomal degradation rescues pentamidine-mediated decreases of KIR2.1 ion channel expression but not that of Kv11.1
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DOI：
10.1016/j.ejphar.2010.10.093
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发表时间：
2011-02-10
影响因子：
5
通讯作者：
van der Heyden, Marcel A. G.
中科院分区：
文献类型：
--
作者：
Nalos, Lukas;de Boer, Teun P.;van der Heyden, Marcel A. G.
抗原虫药物喷他脒抑制两种类型的心脏整流钾电流，这可能导致危及生命的心律失常。在这里，我们使用喷他脒作为工具来研究单一药物是否通过相同或不同的机制影响两个结构不同的钾通道的运输，以及药物的不良反应是否可以通过通道特定的方式被抑制。采用全细胞膜片钳、Western blot、real time PCR和共聚焦激光扫描显微镜分别测定钾电流密度、离子通道蛋白水平、mRNA表达水平和亚细胞定位。我们证明喷他脒抑制延迟（I-Kr）和内向（I-K1）整流在培养的成年犬心肌细胞。在HEK293细胞中，喷他脒抑制负责I-Kr的功能性K(v)11.1通道。通过干扰完全糖基化水平，在质膜上产生较不成熟的K(v)11.1。相比之下，总K(IR)2.1表达水平（I-K1的基础）强烈下降，这不能从mRNA表达水平来解释。除明显糖基化干扰外，未观察到K(IR)2.1蛋白分子大小的变化。剩余的K(IR)2.1蛋白主要在质膜上表达。抑制溶酶体蛋白降解能够部分恢复K(IR)2.1水平，但不能恢复K(v)11.1水平。我们得出结论：1)单一药物可以以亚型特异性模式干扰心脏钾通道运输；2)药物不良反应可以通过通道特异性方式纠正。(C) 2010 Elsevier B.V.版权所有
The antiprotozoal drug pentamidine inhibits two types of cardiac rectifier potassium currents, which can precipitate life-threatening arrhythmias. Here, we use pentamidine as a tool to investigate whether a single drug affects trafficking of two structurally different potassium channels by identical or different mechanisms, and whether the adverse drug effect can be suppressed in a channel specific fashion. Whole cell patch clamp, Western blot, real time PCR, and confocal laser scanning microscopy were used to determine potassium current density, ion channel protein levels, mRNA expression levels, and subcellular localization, respectively. We demonstrate that pentamidine inhibits delayed (I-Kr) and inward (I-K1) rectifier currents in cultured adult canine cardiomyocytes. In HEK293 cells, pentamidine inhibits functional K(v)11.1 channels, responsible for I-Kr. by interfering at the level of full glycosylation, yielding less mature form of K(v)11.1 at the plasma membrane. In contrast, total K(IR)2.1 expression levels, underlying I-K1, are strongly decreased, which cannot be explained from mRNA expression levels. No changes in molecular size of K(IR)2.1 protein were observed, excluding interference in overt glycosylation. Remaining K(IR)2.1 protein is mainly expressed at the plasma membrane. Inhibition of lysosomal protein degradation is able to partially rescue K(IR)2.1 levels, but not those of K(v)11.1. We conclude that 1) a single drug can interfere in cardiac potassium channel trafficking in a subtype specific mode and 2) adverse drug effects can be corrected in a channel specific manner. (C) 2010 Elsevier B.V. All rights reserved.