Molecular basis of reactive oxygen species-induced inactivation of α4β2 nicotinic acetylcholine receptors
Molecular basis of reactive oxygen species-induced inactivation of α4β2 nicotinic acetylcholine receptors
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活性氧诱导的 α4β2 烟碱乙酰胆碱受体失活的分子基础
DOI：
10.1016/j.freeradbiomed.2016.07.012
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发表时间：
2016
影响因子：
7.4
通讯作者：
Jianliang Zhang
中科院分区：
文献类型：
--
作者：
Junjun Zhao;Yan Zheng;Fenqin Xue;Yongchang Chang;Hui Yang;Jianliang Zhang
α4β2神经元烟碱乙酰胆碱受体（nAChR）是脑中最广泛的异聚nAChR亚型，介导快速突触传递。以往的研究表明活性氧（reactive oxygen species，ROS）可使α4β2 nAChRs失活，但其机制尚不清楚。我们发现H_2O_2可诱导人α_4 β_2 nAChRs的乙酰胆碱诱发电流下降，而用丙氨酸取代α_4 Cys 245或β_2 Cys 237的M_1-M_2连接子中保守的半胱氨酸可防止电流下降。在结构上，假设当受体被激活时，α4 Cys 245和β2 Cys 237非常接近。Western blotting结果表明，当激动剂结合的受体遇到H2 O2时，α4和β2亚基发生交联，这可以通过将M1-M2接头中保守的半胱氨酸替换为丙氨酸来防止。因此，当激动剂与受体结合时，α4 Cys 245和β2 Cys 237彼此接近，并且ROS氧化这些保守的半胱氨酸，导致亚基交联并将α4β2 nAChR捕获到失活状态。此外，我们在PC 12细胞中模拟实验性帕金森病（PD）模型，发现6-羟基多巴胺（6-OHDA）产生的ROS可引起α4β2 nAChRs电流下降，这可能在PD中起作用。
The α4β2 neuronal nicotinic acetylcholine receptors (nAChRs) are the most widespread heteromeric nAChR subtype in the brain, mediating fast synaptic transmission. Previous studies showed that α4β2 nAChRs could be inactivated by reactive oxygen species (ROS), but the underlying mechanism is still obscure. We found that H2O2induced the rundown of ACh-evoked currents in human α4β2 nAChRs and the replacement of the conserved cysteine in the M1–M2 linker of either α4 Cys245 or β2 Cys237 with an alanine residue could prevent the current rundown. Structurally, α4 Cys245 and β2 Cys237 are hypothesized to be in close proximity when the receptor is activated. Western blotting results showed that α4 and β2 subunits were cross-linked when the agonist-bound receptor encountered H2O2, which could be prevented by the substitution of the conserved cysteine in the M1–M2 linker to an alanine. Thus, when agonist bound to the receptor, α4 Cys245 and β2 Cys237 came close to each other and ROS oxidized these conserved cysteines, leading subunits to be cross-linked and trapping α4β2 nAChRs into the inactivation state. In addition, we mimicked an experimental Parkinson's disease (PD) model in PC12 cells and found that ROS, generated by 6-hydroxydopamine (6-OHDA), could cause the current rundown in α4β2 nAChRs, which may play a role in PD.