Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
VenomeTech, 473 Route des Dolines, Villa 3, 06560 Valbonne, France.
Neuropharmacology. 2017 Dec;127:185-195. doi: 10.1016/j.neuropharm.2017.03.020. Epub 2017 Mar 19.
Acute pharmacological inhibition of acid-sensing ion channel 1a (ASIC1a) is efficacious in rodent models in alleviating symptoms of neurological diseases such as stroke and multiple sclerosis. Thus, ASIC1a is a promising therapeutic target and selective ligands that modulate it are invaluable research tools and potential therapeutic leads. Spider venoms have provided an abundance of voltage-gated ion channel modulators, however, only one ASIC modulator (PcTx1) has so far been isolated from this source. Here we report the discovery, characterization, and chemical stability of a second spider venom peptide that potently modulates ASIC1a and ASIC1b, and investigate the molecular basis for its subtype selectivity. π-TRTX-Hm3a (Hm3a) is a 37-amino acid peptide isolated from Togo starburst tarantula (Heteroscodra maculata) venom with five amino acid substitutions compared to PcTx1, and is also three residues shorter at the C-terminus. Hm3a pH-dependently inhibited ASIC1a with an IC of 1-2 nM and potentiated ASIC1b with an EC of 46.5 nM, similar to PcTx1. Using ASIC1a to ASIC1b point mutants in rat ASIC1a revealed that Glu177 and Arg175 in the palm region opposite α-helix 5 play an important role in the Hm3a-ASIC1 interaction and contribute to the subtype-dependent effects of the peptide. Despite its high sequence similarity with PcTx1, Hm3a showed higher levels of stability over 48 h. Overall, Hm3a represents a potent, highly stable tool for the study of ASICs and will be particularly useful when stability in biological fluids is required, for example in long term in vitro cell-based assays and in vivo experiments. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
酸敏离子通道 1a（ASIC1a）的急性药理学抑制在缓解中风和多发性硬化等神经疾病的症状方面，在啮齿动物模型中是有效的。因此，ASIC1a 是一个很有前途的治疗靶点，能够调节它的选择性配体是非常有价值的研究工具和潜在的治疗先导物。蜘蛛毒液为电压门控离子通道调节剂提供了丰富的来源，然而，迄今为止，只有一种 ASIC 调节剂（PcTx1）从这种来源中分离出来。在这里，我们报告了一种从蜘蛛毒液中发现、表征和化学稳定性的第二种蜘蛛毒液肽，该肽能够强烈调节 ASIC1a 和 ASIC1b，并研究其亚型选择性的分子基础。π-TRTX-Hm3a（Hm3a）是一种 37 个氨基酸的肽，与 PcTx1 相比，从多哥星爆狼蛛（Heteroscodra maculata）毒液中分离出来时有 5 个氨基酸取代，在 C 末端也短 3 个残基。Hm3a 在 pH 值依赖性下以 1-2 nM 的 IC 抑制 ASIC1a，并以 46.5 nM 的 EC 增强 ASIC1b，与 PcTx1 相似。使用大鼠 ASIC1a 的 ASIC1a 到 ASIC1b 点突变体，发现手掌区对面α-螺旋 5 的 Glu177 和 Arg175 在 Hm3a-ASIC1 相互作用中起着重要作用，并有助于该肽的亚型依赖性作用。尽管 Hm3a 与 PcTx1 具有高度的序列相似性，但它在 48 小时内表现出更高的稳定性水平。总的来说，Hm3a 是研究 ASIC 的一种有效、高度稳定的工具，当在生物流体中需要稳定性时，例如在长期的体外基于细胞的测定和体内实验中，它将特别有用。本文是题为“毒液衍生肽作为药理学工具”的特刊的一部分。
