Allosteric Agonism of α7 Nicotinic Acetylcholine Receptors: Receptor Modulation Outside the Orthosteric Site
Allosteric Agonism of α7 Nicotinic Acetylcholine Receptors: Receptor Modulation Outside the Orthosteric Site
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DOI：
10.1124/mol.119.115758
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发表时间：
2019-06-01
影响因子：
3.6
通讯作者：
Horenstein, Nicole A.
中科院分区：
文献类型：
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作者：
Gulsevin, Alican;Papke, Roger L.;Horenstein, Nicole A.
烟碱乙酰胆碱受体（nAChRs）是配体门控离子通道Cys-loop超家族的成员。通常，通道激活是在激动剂与受体的正位结合位点结合后发生的。α - 7 nachr具有非常低的通道激活概率，这可以通过α - 7选择性正变构调节剂（pam）结合到跨膜结构域内的假设位点来逆转。虽然典型的pam，如PNU-120596，需要正构激动剂的共同作用才能产生大的通道激活，但一些pam，如GAT107和B-973B [(S)-3-（3,4-二氟苯基）- n-（1-（6-（4-（吡啶-2-基）哌嗪-1-基）吡嗪-2-基）乙基）丙酰胺]被定性为变构激活pam，它们也结合胞外区域的变构激活（AA）位点，并自行激活α - 7离子通道。我们之前已经表征了具有不同功能的N，N-二乙基-N'-苯基哌嗪类似物。在这项工作中，我们将这个家族的成员与α 7受体细胞外结构域的同源模型对接。化合物1,1-二乙基-4（萘-2-基）哌嗪-1-ium （2NDEP）是一种弱的部分激动剂，在假定的受体AA位点显示出特别有利的对接和结合能。我们假设2NDEP可以通过AA位点与PAMs偶联。这一假设用α 7突变体C190A进行了验证，C190A不被正构激动剂激活，但被GAT107有效激活。结果表明，2NDEP与PAM PNU-120596共作用时，可作为α - 7C190A的变构激动剂。此外，与AA位点选择性拮抗剂2,3,5,6mp - tqs（顺式-反式4-（2,3,5,6-四甲基苯基）-3a, 4,5,9b-四氢- 3h -环戊[c]喹啉-8-磺胺）共施用后，变构活性几乎消失，与AA位点参与一致。总的来说，我们的研究结果显示了一种通过α 7 nAChR细胞外区域的变构位点的激动作用的新模式。
Nicotinic acetylcholine receptors (nAChRs) are members of the Cys-loop superfamily of ligand-gated ion channels. Typically, channel activation follows the binding of agonists to the orthosteric binding sites of the receptor. alpha 7 nAChRs have a very low probability of channel activation, which can be reversed by the binding of alpha 7 selective positive allosteric modulators (PAMs) to putative sites within the transmembrane domains. Although typical PAMs, like PNU-120596, require coapplication of an orthosteric agonist to produce large channel activations, some, like GAT107 and B-973B [(S)-3-(3,4-difluorophenyl)-N-(1-(6-(4-(pyridin-2-yl)piperazin-1-yl)pyrazin-2-yl)ethyl)propanamide], are characterized as allosteric activating PAMs, which also bind to an allosteric activation (AA) site in the extracellular domain and activate the alpha 7 ion channel by themselves. We had previously characterized N,N-diethyl-N'-phenylpiperazine analogs with various functions. In this work, we docked members of this family to a homology model of the alpha 7 receptor extracellular domain. The compound 1,1-diethyl-4(naphthalene-2-yl)piperazin-1-ium (2NDEP) a weak partial agonist, showed particularly favorable docking and binding energies at the putative AA site of the receptor. We hypothesized that 2NDEP could couple with PAMs through the AA site. This hypothesis was tested with the alpha 7 mutant C190A, which is not activated by orthosteric agonists but is effectively activated by GAT107. The results showed that 2NDEP acts as an allosteric agonist of alpha 7C190A when coapplied with the PAM PNU-120596. Also, the allosteric activity was nearly abolished upon coapplication with the AA site-selective antagonist 2,3,5,6MP-TQS (cis-trans-4-(2,3,5,6-tetramethylphenyl)-3a, 4,5,9b-tetrahydro-3H-cyclopenta[c]quinoline-8-sulfonamide), consistent with AA site involvement. Overall, our findings show a novel mode of agonism through an allosteric site in the extracellular domain of alpha 7 nAChR.