PDF(Pubmed)
Abstract：
The pathophysiological mechanisms underlying the constellation of symptoms that characterize COVID-19 are only incompletely understood. In an effort to fill these gaps, a \"nicotinic hypothesis,\" which posits that nicotinic acetylcholine receptors (AChRs) act as additional severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptors, has recently been put forth. A key feature of the proposal (with potential clinical ramifications) is the suggested competition between the virus\' spike protein and small-molecule cholinergic ligands for the receptor\'s orthosteric binding sites. This notion is reminiscent of the well-established role of the muscle AChR during rabies virus infection. To address this hypothesis directly, we performed equilibrium-type ligand-binding competition assays using the homomeric human α7-AChR (expressed on intact cells) as the receptor, and radio-labeled α-bungarotoxin (α-BgTx) as the orthosteric-site competing ligand. We tested different SARS-CoV-2 spike protein peptides, the S1 domain, and the entire S1-S2 ectodomain, and found that none of them appreciably outcompete [125I]-α-BgTx in a specific manner. Furthermore, patch-clamp recordings showed no clear effect of the S1 domain on α7-AChR-mediated currents. We conclude that the binding of the SARS-CoV-2 spike protein to the human α7-AChR\'s orthosteric sites-and thus, its competition with ACh, choline, or nicotine-is unlikely to be a relevant aspect of this complex disease.
摘要：
COVID-19症状的病理生理机制尚不完全清楚。为了填补这些空白，一个“烟碱假说，“认为烟碱乙酰胆碱受体（AChRs）作为额外的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）受体，最近有人提出。该建议的一个关键特征（具有潜在的临床后果）是病毒刺突蛋白和小分子胆碱能配体之间对受体正构结合位点的竞争。这个概念让人想起狂犬病病毒感染期间肌肉AChR的公认作用。为了直接解决这个假设，我们使用同源人α7-AChR（在完整细胞上表达）作为受体进行平衡型配体结合竞争测定，和放射性标记的α-银环蛇毒素（α-BgTx）作为正构位点竞争配体。我们测试了不同的SARS-CoV-2刺突蛋白肽，S1域，和整个S1-S2胞外域，并发现它们都没有以特定的方式明显胜过[125I]-α-BgTx。此外，膜片钳记录显示S1结构域对α7-AChR介导的电流无明显影响.我们得出结论，SARS-CoV-2刺突蛋白与人α7-AChR的正构位点结合，因此，它与ACh的竞争，胆碱，或尼古丁-不太可能是这种复杂疾病的相关方面。
