A Novel Pan-Negative-Gating Modulator of K<sub>Ca</sub>2/3 Channels, Fluoro-Di-Benzoate, RA-2, Inhibits Endothelium-Derived Hyperpolarization–Type Relaxation in Coronary Artery and Produces Bradycardia In Vivo
作者:Aida Oliván-Viguera、Marta Sofía Valero、Nicole Coleman、Brandon M. Brown、Celia Laría、María Divina Murillo、José A. Gálvez、María D. Díaz-de-Villegas、Heike Wulff、Ramón Badorrey、Ralf Köhler
DOI:10.1124/mol.114.095745
日期:2015.2
Small/intermediate conductance KCa channels (KCa2/3) are Ca2+/calmodulin regulated K+ channels that produce membrane hyperpolarization and shape neurologic, epithelial, cardiovascular, and immunologic functions. Moreover, they emerged as therapeutic targets to treat cardiovascular disease, chronic inflammation, and some cancers. Here, we aimed to generate a new pharmacophore for negative-gating modulation of KCa2/3 channels. We synthesized a series of mono- and dibenzoates and identified three dibenzoates [1,3-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate) (RA-2), 1,2-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate), and 1,4-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate)] with inhibitory efficacy as determined by patch clamp. Among them, RA-2 was the most drug-like and inhibited human KCa3.1 with an IC50 of 17 nM and all three human KCa2 subtypes with similar potencies. RA-2 at 100 nM right-shifted the KCa3.1 concentration-response curve for Ca2+ activation. The positive-gating modulator naphtho[1,2- d ]thiazol-2-ylamine (SKA-31) reversed channel inhibition at nanomolar RA-2 concentrations. RA-2 had no considerable blocking effects on distantly related large-conductance KCa1.1, Kv1.2/1.3, Kv7.4, hERG, or inwardly rectifying K+ channels. In isometric myography on porcine coronary arteries, RA-2 inhibited bradykinin-induced endothelium-derived hyperpolarization (EDH)–type relaxation in U46619-precontracted rings. Blood pressure telemetry in mice showed that intraperitoneal application of RA-2 (≤100 mg/kg) did not increase blood pressure or cause gross behavioral deficits. However, RA-2 decreased heart rate by ≈145 beats per minute, which was not seen in KCa3.1−/− mice. In conclusion, we identified the KCa2/3–negative-gating modulator, RA-2, as a new pharmacophore with nanomolar potency. RA-2 may be of use to generate structurally new types of negative-gating modulators that could help to define the physiologic and pathomechanistic roles of KCa2/3 in the vasculature, central nervous system, and during inflammation in vivo.
小/中等导电性KCa通道(KCa2/3)是由Ca2+/钙调蛋白调控的K+通道,能够引起膜超极化,从而影响神经、上皮、心血管和免疫功能。此外,它们被作为治疗心血管疾病、慢性炎症和某些癌症的治疗靶点。在此,我们的目标是为KCa2/3通道的负门控调节生成一个新的药效团。我们合成了一系列单和二苯酸酯,并确定了三种具有抑制效力的二苯酸酯[1,3-苯二亚甲基双(3-氟-4-羟基苯酸酯)(RA-2),1,2-苯二亚甲基双(3-氟-4-羟基苯酸酯)和1,4-苯二亚甲基双(3-氟-4-羟基苯酸酯)],其抑制效能通过膜片钳测试确定。其中,RA-2是最具药物相似性的,IC50为17 nM,能够抑制人类KCa3.1,并以相似的效力抑制所有三种人类KCa2亚型。RA-2在100 nM时使KCa3.1的Ca2+激活浓度-反应曲线向右移动。正门控调节剂萘并[1,2-d]噻唑-2-氨基(SKA-31)在纳摩尔RA-2浓度下逆转了通道抑制。RA-2对远相关的大导电性KCa1.1、Kv1.2/1.3、Kv7.4、hERG或内向整流K+通道无显著阻断作用。在猪冠状动脉的等张肌肉测定中,RA-2抑制了由缓激肽引起的内皮源超极化(EDH)型松弛。在小鼠的血压遥测中,腹腔注射RA-2(≤100 mg/kg)未增加血压或造成明显的行为缺陷。然而,RA-2降低了心率约145次每分钟,而这在KCa3.1−/−小鼠中未见到。总之,我们鉴定了负门控调节剂KCa2/3,RA-2,作为一种具有纳摩尔效力的新药效团。RA-2可能有助于生成结构上新类型的负门控调节剂,这有助于阐明KCa2/3在血管、中央神经系统及炎症过程中的生理和病理机制作用。