Mutational and In Silico Analyses for Antidepressant Block of Astroglial Inward-Rectifier Kir4.1 Channel
Mutational and In Silico Analyses for Antidepressant Block of Astroglial Inward-Rectifier Kir4.1 Channel
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DOI：
10.1124/mol.108.052936
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发表时间：
2009-06-01
影响因子：
3.6
通讯作者：
Kurachi, Yoshihisa
中科院分区：
文献类型：
--
作者：
Furutani, Kazuharu;Ohno, Yukihiro;Kurachi, Yoshihisa
药物与靶蛋白（包括离子通道）的相互作用对于各种细胞功能的药理学控制是必不可少的，但其大部分分子机制仍然是难以捉摸的。我们最近发现，一系列抗抑郁药优先阻断星形胶质细胞K+缓冲内向整流钾通道（Kir）4.1通道而不是Kir1.1通道。在此，使用对突变的Kir4.1通道的药物作用的电生理学分析以及配体的三维（3D）排列的计算分析（即，双向分析），我们研究了抗抑郁药-Kir4.1通道相互作用的潜在机制。首先，选择性5-羟色胺再摄取抑制剂氟西汀和三环类抗抑郁药去甲替林嵌合和位点定向突变体的非洲爪蟾卵母细胞中表达的Kir4.1的影响进行了研究，使用双电极电压钳技术。跨膜结构域2上的两个氨基酸Thr 128和Glu 158对药物抑制电流至关重要。Kir4.1孔的封闭和开放构象模型表明，这两个残基面临的中心腔，它们被定位在能够与药物相互作用的几何范围内。其次，为了用几何术语表示活性配体的分子性质，生成了抗抑郁药的3D定量构效关系模型，这表明它们具有携带氢键受体和带正电荷部分的共同特征。将受体和配体的三维结构和理化性质进行了拟合。我们的研究结果强烈表明，抗抑郁药与Kir4.1通道孔残基通过氢键和离子相互作用相互作用，这解释了它们对Kir4.1电流的优先抑制作用。本研究可能代表了一个可能的一般性的方法来了解配体-蛋白质相互作用的机制。
Drug interaction with target proteins including ion channels is essential for pharmacological control of various cellular functions, but the majority of its molecular mechanisms is still elusive. We recently found that a series of antidepressants preferentially block astroglial K+-buffering inwardly rectifying potassium channel (Kir) 4.1 channels over Kir1.1 channels. Here, using electrophysiological analyses of drug action on mutated Kir4.1 channel as well as computational analyses of three-dimensional (3D) arrangements of the ligands (i.e., bidirectional analyses), we examined the underlying mechanism for the antidepressant-Kir4.1 channel interaction. First, the effects of the selective serotonin reuptake inhibitor fluoxetine and the tricyclic antidepressant nortriptyline on chimeric and site-directed mutants of Kir4.1 expressed in Xenopus laevis oocytes were examined using the two-electrode voltage-clamp technique. Two amino acids, Thr128 and Glu158, on transmembrane domain 2 were critical for the drug inhibition of the current. The closed and open conformation models of the Kir4.1 pore suggested that both residues faced the central cavity, and they were positioned within a geometrical range capable of interacting with the drugs. Second, to represent molecular properties of active ligands in geometric terms, a 3D quantitative structure-activity relationship model of antidepressants was generated, which suggested that they share common features bearing a hydrogen bond acceptor and a positively charged moiety. 3D structures and physicochemical features of receptor and ligand were fitted together. Our results strongly suggest that antidepressants interact with Kir4.1 channel pore residues by hydrogen bond and ionic interactions, which account for their preferential inhibitory action on Kir4.1 current. This study may represent a possible general approach for the understanding of the mechanism of ligand-protein interactions.