Figure S1 - Human α4β2 Nicotinic Acetylcholine Receptor as a Novel Target of Oligomeric α-Synuclein

Effects of pretreatment of oligomeric amyloid (Aβ1-42) on α-synuclein-induced inhibition of human α4β2-nAChRs heterologously expressed in SH-EP1 cell line. We found that after 10 min pre-treatment with 1 nM oligomeric Aβ1-42, 3 µM nicotine (around EC50 concentration)-induced inward current was reduced (Figure S1A, blue trace). Thereafter, we immediately added 10 nM α-synuclein (in the continuous presence of 1 nM Aβ1-42) for 10 min, and then tested nicotinic response. However, we did not observe further reduction of nicotine-induced inward current (Figure S1A, red trace). Statistic analysis showed that Aβ1-42 pre-treatment significantly reduced both peak and steady-state components of nicotine-induced-whole-cell current (Figure S1B, n = 6, pp>0.05 between Aβ1-42 and α-synuclein treated group), indicated as no significance (NS) in the figure. These results suggest that both oligomeric molecules of Aβ1-42 and α-synuclein likely bind to a common negative allosteric site to reduce human α4β2-nAChR function. (DOC)寡聚型淀粉样蛋白（Aβ1-42）预处理对α-突触核蛋白（α-synuclein）诱导的、在SH-EP1细胞系中异源表达的人源α4β2烟碱型乙酰胆碱受体（α4β2-nAChRs）抑制效应的影响。我们发现，经1 nM寡聚型Aβ1-42预处理10分钟后，3 µM尼古丁（约为半最大效应浓度（EC50））诱导的内向电流出现减弱（图S1A，蓝色轨迹）。随后，我们立即在持续存在1 nM Aβ1-42的体系中加入10 nM α-突触核蛋白并孵育10分钟，随后再次检测烟碱型受体应答。然而，我们未观察到尼古丁诱导的内向电流出现进一步减弱（图S1A，红色轨迹）。统计分析显示，Aβ1-42预处理可显著降低尼古丁诱导的全细胞电流的峰值与稳态分量（图S1B，n=6，Aβ1-42组与α-突触核蛋白处理组间P>0.05，图中标记为无显著性差异（NS））。上述结果表明，Aβ1-42与α-突触核蛋白这两种寡聚分子可能通过结合同一负变构位点（negative allosteric site），从而削弱人源α4β2烟碱型乙酰胆碱受体的功能。（DOC）