The modulation of acid-sensing ion channel 1 by PcTx1 is pH-, subtype- and species-dependent: Importance of interactions at the channel subunit interface and potential for engineering selective analogues
The modulation of acid-sensing ion channel 1 by PcTx1 is pH-, subtype- and species-dependent: Importance of interactions at the channel subunit interface and potential for engineering selective analogues
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DOI：
10.1016/j.bcp.2019.03.004
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发表时间：
2019-05-01
影响因子：
5.8
通讯作者：
Rash, Lachlan D.
中科院分区：
文献类型：
--
作者：
Cristofori-Armstrong, Ben;Saez, Natalie J.;Rash, Lachlan D.
酸敏感离子通道（ASIC）是哺乳动物神经系统中的主要酸传感器，在局部酸中毒条件下被质子激活。它们与一系列病理学有关，包括缺血性卒中（ASIC1a亚型）和外周疼痛（ASIC1b和ASIC3）。虽然蜘蛛毒肽PcTx1是研究最多的ASIC调节剂，并且在缺血性中风的啮齿动物模型中具有神经保护作用，但很少有实验工作来研究其与人类ASIC1a或脱靶ASIC1b的分子相互作用。PcTx1的酸性口袋结合位点的互补面是这些通道序列不同的地方。我们在这里表明，虽然PcTx1在人类ASIC1a的效力比大鼠通道低10倍，但这两个通道的表观亲和力是相当的。我们检查了PcTx1对人ASIC1a和大鼠ASIC1b的药效团，并表明每个ASIC1变体的抑制和刺激作用主要由一组与拇指结构域结合的核心肽药效团残基驱动，而与结合位点的互补面相互作用的肽残基是物种和亚型的基础，活性的依赖性差异可以允许操纵ASIC 1变体选择性。最后，在微碱性pH下应用时，PcTx1对大鼠ASIC 1a的刺激作用与低受体占有率相关。PcTx1与ASIC1亚型之间相互作用的这些新见解表明了其作用机制的复杂性，并强调了使用PcTx1作为研究ASIC功能的药理学工具时要考虑的重要意义。
Acid-sensing ion channels (ASICs) are primary acid sensors in the mammalian nervous system that are activated by protons under conditions of local acidosis. They have been implicated in a range of pathologies including ischemic stroke (ASIC1a subtype) and peripheral pain (ASIC1b and ASIC3). Although the spider venom peptide PcTx1 is the best-studied ASIC modulator and is neuroprotective in rodent models of ischemic stroke, little experimental work has been done to examine its molecular interaction with human ASIC1a or the off-target ASIC1b. The complementary face of the acidic pocket binding site of PcTx1 is where these channels differ in sequence. We show here that although PcTx1 is 10-fold less potent at human ASIC1a than the rat channel, the apparent affinity for the two channels is comparable. We examined the pharmacophore of PcTx1 for human ASIC1a and rat ASIC1b, and show that inhibitory and stimulatory effects at each ASIC1 variant is driven mostly by a shared set of core peptide pharmacophore residues that bind to the thumb domain, while peptide residues that interact with the complementary face of the biding site underlie species and subtype-dependent differences in activity that may allow manipulation of ASIC1 variant selectivity. Finally, the stimulatory effect of PcTx1 on rat ASIC1a when applied under mildly alkaline pH correlates with low receptor occupancy. These new insights into the interactions between PcTx1 with ASIC1 subtypes demonstrates the complexity of its mechanism of action, and highlights important implications to consider when using PcTx1 as a pharmacological tool to study ASIC function.