Presence of multiple binding sites on α9α1 0 nAChR receptors alludes to stoichiometric-dependent action of the α-conotoxin, Vc1.1
Presence of multiple binding sites on α9α1 0 nAChR receptors alludes to stoichiometric-dependent action of the α-conotoxin, Vc1.1
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DOI：
10.1016/j.bcp.2014.02.002
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发表时间：
2014-05-01
影响因子：
5.8
通讯作者：
Chebib, Mary
中科院分区：
文献类型：
--
作者：
Indurthi, Dinesh C.;Pera, Elena;Chebib, Mary
烟碱乙酰胆碱受体（nAChRs）是参与快速突触传递的配体门控离子通道。nachr是由不同或相似亚基组合形成的五聚体受体，可产生异质或同质通道。α 9 α 10 nAChR亚型因其在听觉系统中的作用而闻名，在耳蜗毛细胞中表达。这些nachr也被证明参与免疫调节。α 9 α 10 nachr拮抗剂，如α - concontoxin Vc1.1，对神经性疼痛具有镇痛作用。与其他nAChR亚型不同，没有证据表明α 9 α 10的功能性受体化学计量存在。通过使用双电极电压钳法和维持恒定的细胞内Ca2+浓度，我们观察到乙酰胆碱的双相激活曲线依赖于受体化学计量学vc1.1，而不是α 9 α 10拮抗剂RgIA或阿托品，以双相方式抑制乙酰胆碱诱发电流。通过改变α 9和α 10 mRNA注入卵母细胞的比例，可以改变ACh和Vc1.1的激活和抑制曲线特征，过量α 10 mRNA注入卵母细胞时，ACh和Vc1.1的激活和抑制曲线由双相变为单相。这些结果强调了至少两种不同的α 9 α 10 nAChR化学计量学的药理学特征差异，可能是（α 9）(3)(α 10)(2)和（α 9）(2)(α 10)(3)。因此，我们推断，在假设的（α 9）(3)(α 10)(2) nAChR上，除了α 10- α 9和或α 9- α 10界面外，在α 9- α 9界面上，ACh和Vc1.1还有一个额外的结合位点。这项研究提供了进一步的证据，受体化学计量学有助于理解Cys-loop受体的另一层复杂性。(C) 2014爱思唯尔公司版权所有。
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels involved in fast synaptic transmission. nAChRs are pentameric receptors formed from a combination of different or similar subunits to produce heteromeric or homomeric channels. The heteromeric, alpha 9 alpha 10 nAChR subtype is well-known for its role in the auditory system, being expressed in cochlear hair cells. These nAChRs have also been shown to be involved in immune-modulation. Antagonists of a alpha 9 alpha 10 nAChRs, like the alpha-conotoxin Vc1.1, have analgesic effects in neuropathic pain. Unlike other nAChR subtypes there is no evidence that functional receptor stoichiometries of alpha 9 alpha 10 exist. By using 2-electrode voltage clamp methods and maintaining a constant intracellular Ca2+ concentration, we observed a biphasic activation curve for ACh that is dependent on receptor stoichiometry.Vc1.1, but not the alpha 9 alpha 10 antagonists RgIA or atropine, inhibits ACh-evoked currents in a biphasic manner. Characteristics of the ACh and Vc1.1 activation and inhibition curves can be altered by varying the ratio of alpha 9 and alpha 10 mRNA injected into oocytes, changing the curves from biphasic to monophasic when an excess of alpha 10 mRNA is used. These results highlight the difference in the pharmacological profiles of at least two different alpha 9 alpha 10 nAChR stoichiometries, possibly (alpha 9)(3)(alpha 10)(2) and (alpha 9)(2)(alpha 10)(3). As a result, we infer that there is an additional binding site for ACh and Vc1.1 at the alpha 9-alpha 9 interface on the hypothesized (alpha 9)(3)(alpha 10)(2) nAChR, in addition to the alpha 10-alpha 9 and or alpha 9-alpha 10 interfaces that are common to both stoichiometries. This study provides further evidence that receptor stoichiometry contributes another layer of complexity in understanding Cys-loop receptors. (C) 2014 Elsevier Inc. All rights reserved.