Inhibitory effects and mechanism of dihydroberberine on hERG channels expressed in HEK293 cells.
Inhibitory effects and mechanism of dihydroberberine on hERG channels expressed in HEK293 cells.
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二氢小檗碱对HEK293细胞hERG通道的抑制作用及机制
DOI：
10.1371/journal.pone.0181823
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Li B
中科院分区：
文献类型：
--
作者：
Yu D;Lv L;Fang L;Zhang B;Wang J;Zhan G;Zhao L;Zhao X;Li B
人ether-a-go-go-related基因（hERG）钾通道传导快速延迟整流钾电流（IKr），并促进III相心脏动作电位复极。药物通过与hERG螺旋中的芳香残基结合来抑制hERG通道。小檗碱（BBR）具有多种药理作用，其氢化衍生物二氢小檗碱（DHB）是一种潜在的新药候选药物。以往的研究表明BBR阻断hERG通道和延长动作电位时程（APD）。本研究旨在探讨DHB对hERG通道的作用及其机制。蛋白质表达和hERG电流分别用蛋白质印迹和膜片钳分析。DHB抑制hERG电流浓度依赖性瞬时灌注后，加速通道失活直接结合酪氨酸（Tyr 652）和苯丙氨酸（Phe 656），并减少成熟（155-kDa）和同时增加未成熟（135-kDa）hERG的表达，分别。这表明hERG通道的前向运输中断。此外，DHB显着降低热休克蛋白90（Hsp 90）的表达及其与hERG的相互作用，表明DHB破坏通道折叠破坏hERG运输。同时DHB还能增强未折叠蛋白反应（UPR）的生物标志物--切割转录激活因子6（ATF-6）的表达。钙连接蛋白和钙网蛋白（由ATF-6激活以促进通道折叠的分子伴侣）的表达也增加，这表明UPR激活。此外，成熟的155-kDa hERG的降解率增加DHB暴露后。总之，我们证明DHB通过结合芳香族Tyr 652和Phe 656来急性阻断hERG通道。DHB可能通过两种途径降低hERG质膜表达，包括破坏未成熟hERG通道的正向运输和增强成熟hERG通道的降解。此外，正向运输被受损的通道折叠破坏，与hERG蛋白和伴侣蛋白之间的相互作用改变相关。最后，运输抑制激活UPR，成熟的hERG通道降解增加DHB。
The human ether-a-go-go-related gene (hERG) potassium channel conducts rapid delayed rectifier potassium currents (IKr) and contributes to phase III cardiac action potential repolarization. Drugs inhibit hERG channels by binding to aromatic residues in hERG helixes. Berberine (BBR) has multiple actions, and its hydrogenated derivative dihydroberberine (DHB) is a potential candidate for developing new drugs. Previous studies have demonstrated that BBR blocks hERG channels and prolongs action potential duration (APD). Our present study aimed to investigate the effects and mechanism of DHB on hERG channels. Protein expression and the hERG current were analyzed using western blotting and patch-clamp, respectively. DHB inhibited the hERG current concentration-dependently after instantaneous perfusion, accelerated channel inactivation by directly binding tyrosine (Tyr652) and phenylalanine (Phe656), and decreased mature (155-kDa) and simultaneously increased immature (135-kDa) hERG expression, respectively. This suggests disruption of forward trafficking of hERG channels. Besides, DHB remarkably reduced heat shock protein 90 (Hsp90) expression and its interaction with hERG, indicating that DHB disrupted hERG trafficking by impairing channel folding. Meanwhie, DHB enhanced the expression of cleaved activating transcription factor-6 (ATF-6), a biomarker of unfolded protein response (UPR). Expression of calnexin and calreticulin, chaperones activated by ATF-6 to facilitate channel folding, were also increased, which indicating UPR activation. Additionally, the degradation rate of mature 155-kDa hERG increased following DHB exposure. In conclusion, we demonstrated that DHB acutely blocked hERG channels by binding the aromatic Tyr652 and Phe656. DHB may decrease hERG plasma membrane expression through two pathways involving disruption of forward trafficking of immature hERG channels and enhanced degradation of mature hERG channels. Furthermore, forward trafficking was disrupted by impaired channel folding associated with altered interactions between hERG proteins and chaperones. Finally, trafficking inhibition activated UPR, and mature hERG channel degradation was increased by DHB.
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影响因子：
120.1
作者：
Waring, Michael J.;Arrowsmith, John;Weir, Alex
通讯作者：
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7.4
作者：
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通讯作者：
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