Abstract：
The Kv4.3 channel features fast N-type inactivation and also undergoes a slow C-type inactivation. The gain-of-function mutations of Kv4.3 channels cause an inherited disease called Brugada syndrome (BrS), characterized by a shortened duration of cardiac action potential repolarization and ventricular arrhythmia. The sulfonylurea drug gliquidone, an ATP-dependent K+ channel antagonist, is widely used for the treatment of type 2 diabetes. Here, we report a novel role of gliquidone in inhibiting Kv4.3 and Kv4.3/KChIP2 channels that encode the cardiac transient outward K+ currents responsible for the initial phase of action potential repolarization. Gliquidone results in concentration-dependent inhibition of both Kv4.3 and Kv4.3/KChIP2 fast or steady-state inactivation currents with an IC50 of approximately 8 μM. Gliquidone also accelerates Kv4.3 channel inactivation and shifts the steady-state activation to a more depolarizing direction. Site-directed mutagenesis and molecular docking reveal that the residues S301 in the S4 and Y312A and L321A in the S4-S5 linker are critical for gliquidone-mediated inhibition of Kv4.3 currents, as mutating those residues to alanine significantly reduces the potency for gliquidone-mediated inhibition. Furthermore, gliquidone also inhibits a gain-of-function Kv4.3 V392I mutant identified in BrS patients in voltage- and concentration-dependent manner. Taken together, our findings demonstrate that gliquidone inhibits Kv4.3 channels by acting on the residues in the S4 and the S4-S5 linker. Therefore, gliquidone may hold repurposing potential for the therapy of Brugada syndrome. SIGNIFICANCE STATEMENT: We describe a novel role of gliquidone in inhibiting cardiac Kv4.3 currents and the channel gain-of-function mutation identified from patients with Brugada syndrome, suggesting its repurposing potential for therapy for the heart disease.
摘要：
Kv4.3通道具有快速N型失活的特征，也经历了缓慢的C型失活。Kv4.3通道的功能获得突变会导致一种遗传性疾病，称为Brugada综合征，其特征是心脏动作电位复极化和室性心律失常的持续时间缩短。磺酰脲类药物格列喹酮,ATP依赖性钾通道拮抗剂，广泛用于2型糖尿病的治疗。这里,我们报道了格列喹酮在抑制Kv4.3和Kv4.3/KChIP2通道中的新作用,这些通道编码负责动作电位复极化初始阶段的心脏Ito电流.格列喹酮导致Kv4.3和Kv4.3/KChIP2快速或稳态失活电流的浓度依赖性抑制，IC50约为8μM。格列喹酮还加速Kv4.3通道失活，并将稳态激活移至更去极化的方向。定点诱变和分子对接揭示了S4和Y312A中的S301残基,S4-S5接头中的L321A对格列喹酮介导的Kv4.3电流抑制至关重要，因为将这些残基突变为丙氨酸会显著降低格列喹酮介导的抑制效力。此外，格列喹酮还以电压和浓度依赖性方式抑制在BrS患者中鉴定的功能获得Kv4.3V392I突变体。一起来看,我们的发现表明格列喹酮通过作用于S4和S4-S5接头中的残基来抑制Kv4.3通道.因此,格列喹酮可能具有治疗Brugada综合征的再利用潜力。意义陈述我们描述了格列喹酮在抑制心脏Kv4.3电流和从Brugada综合征患者鉴定的通道功能获得突变中的新作用。这表明它在心脏病治疗中的潜在用途。
