Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA.
Enteric Neuroscience Program (ENSP), Division of Gastroenterology & Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, 55905, USA.
Cell Mol Life Sci. 2021 Feb;78(4):1565-1575. doi: 10.1007/s00018-020-03592-x. Epub 2020 Jul 16.
Nicotinic acetylcholine receptors (nAChRs) belong to the superfamily of pentameric ligand-gated ion channels, and in neuronal tissues, are assembled from various types of α- and β-subunits. Furthermore, the subunits α4 and β2 assemble in two predominant stoichiometric forms, (α4)(β2) and (α4)(β2), forming receptors with dramatically different sensitivity to agonists and allosteric modulators. However, mechanisms by which the two stoichiometric forms are regulated are not known. Here, using heterologous expression in mammalian cells, single-channel patch-clamp electrophysiology, and calcium imaging, we show that the ER-resident protein NACHO selectively promotes the expression of the (α4)(β2) stoichiometry, whereas the cytosolic molecular chaperone 14-3-3η selectively promotes the expression of the (α4)(β2) stoichiometry. Thus, NACHO and 14-3-3η are potential physiological regulators of subunit stoichiometry, and are potential drug targets for re-balancing the stoichiometry in pathological conditions involving α4β2 nAChRs such as nicotine dependence and epilepsy.
烟碱型乙酰胆碱受体（nAChRs）属于五聚体配体门控离子通道超家族，在神经元组织中，由各种类型的α-和β-亚基组装而成。此外，亚基α4 和 β2 以两种主要的化学计量形式（α4）（β2）和（α4）（β2）组装，形成对激动剂和变构调节剂具有显著不同敏感性的受体。然而，两种化学计量形式的调节机制尚不清楚。在这里，我们使用哺乳动物细胞中的异源表达、单通道膜片钳电生理学和钙成像，表明内质网驻留蛋白 NACHO 选择性促进（α4）（β2）化学计量的表达，而细胞质分子伴侣 14-3-3η 选择性促进（α4）（β2）化学计量的表达。因此，NACHO 和 14-3-3η 可能是亚基化学计量的生理调节剂，并且可能是涉及α4β2 nAChRs 的病理条件下重新平衡化学计量的潜在药物靶点，例如尼古丁依赖和癫痫。
