Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K.
J Am Chem Soc. 2022 Sep 7;144(35):16101-16117. doi: 10.1021/jacs.2c06495. Epub 2022 Aug 25.
Nicotinic acetylcholine receptors (nAChRs) play an important role in neurotransmission and are also involved in addiction and several disease states. There is significant interest in therapeutic targeting of nAChRs; however, achieving selectivity for one subtype over others has been a longstanding challenge, given the close structural similarities across the family. Here, we characterize binding interactions in the α3β4 nAChR subtype via structure-function studies involving noncanonical amino acid mutagenesis and two-electrode voltage clamp electrophysiology. We establish comprehensive binding models for both the endogenous neurotransmitter ACh and the smoking cessation drug cytisine. We also use a panel of C(10)-substituted cytisine derivatives to probe the effects of subtle changes in the ligand structure on binding. By comparing our results to those obtained for the well-studied α4β2 subtype, we identify several features of both the receptor and agonist structure that can be utilized to enhance selectivity for either α3β4 or α4β2. Finally, we characterize binding interactions of the α3β4-selective partial agonist AT-1001 to determine factors that contribute to its selectivity. These results shed new light on the design of selective nAChR-targeted ligands and can be used to inform the design of improved therapies with minimized off-target effects.
烟碱型乙酰胆碱受体（nAChRs）在神经递质传递中发挥着重要作用，同时也与成瘾和多种疾病状态有关。针对 nAChRs 的治疗性靶向具有重要意义；然而，鉴于家族内各亚型间具有紧密的结构相似性，实现对特定亚型的选择性一直是一个长期存在的挑战。在这里，我们通过涉及非典型氨基酸突变和双电极电压钳电生理学的结构-功能研究，对 α3β4 nAChR 亚型的结合相互作用进行了表征。我们建立了内源性神经递质 ACh 和戒烟药物 cytisine 的综合结合模型。我们还使用了一组 C(10)-取代 cytisine 衍生物来探测配体结构细微变化对结合的影响。通过将我们的结果与经过充分研究的 α4β2 亚型的结果进行比较，我们确定了受体和激动剂结构的几个特征，这些特征可用于增强对 α3β4 或 α4β2 的选择性。最后，我们对 α3β4 选择性部分激动剂 AT-1001 的结合相互作用进行了表征，以确定对其选择性有贡献的因素。这些结果为设计选择性 nAChR 靶向配体提供了新的思路，并可用于指导设计具有最小脱靶效应的改进疗法。
