Dual Antagonism of α9α10 nAChR and GABAB Receptor-Coupled CaV2.2 Channels by an Analgesic αO-Conotoxin Analogue

Pain severely affects the physical and mental health
of patients.
The need to develop nonopioid analgesic drugs to meet medical demands
is urgent. In this study, we designed a truncated analogue of αO-conotoxin,
named GeX-2, based on disulfide-bond deletion and sequence truncation.
GeX-2 retained the potency of its parent peptide at the human α9α10
nAChR and exhibited potent inhibitory activity at CaV2.2
channels via activation of the GABAB receptor (GABABR). Importantly, GeX-2 significantly alleviated pain in the
rat model of chronic constriction injury. The dual inhibition of GeX-2
at both α9α10 nAChRs and CaV2.2 channels is
speculated to synergistically mediate the potent analgesic effects.
Results from site-directed mutagenesis assay and computational modeling
suggest that GeX-2 preferentially interacts with the α10(+)α10(−)
binding site of α9α10 nAChR and favorably binds to the
top region of the GABABR2 subunit. The study offers vital
insights into the molecular action mechanism of GeX-2, demonstrating
its potential as a novel nonopioid analgesic.

疼痛对患者的身心健康造成严重影响。为满足医疗需求，开发非阿片类镇痛药物的需求迫在眉睫。在本研究中，我们基于二硫键删除和序列截断，设计了一种αO-孔毒素的截断类似物，命名为GeX-2。GeX-2在人类α9α10烟碱型乙酰胆碱受体（nAChR）上保留了其母肽的效力，并通过激活γ-氨基丁酸B型受体（GABABR）在CaV2.2通道上表现出强大的抑制作用。重要的是，GeX-2在慢性结扎损伤大鼠模型中显著缓解了疼痛。GeX-2在α9α10 nAChRs和CaV2.2通道上的双重抑制作用推测可能协同介导其强大的镇痛效果。定向突变分析和计算建模的结果表明，GeX-2优先与α9α10 nAChR的α10(+)α10(−)结合位点相互作用，并有利于与GABABR2亚单位的顶部区域结合。本研究为GeX-2的分子作用机制提供了重要见解，证明了其作为新型非阿片类镇痛剂的潜力。