钾通道在MPP+诱导的α-synuclein转基因细胞凋亡中的作用

 目的帕金森氏病(PD)的主要病理表现为中脑黑质致密部多巴胺能神经元的进行性死亡,为了揭示帕金森氏病中多巴胺能神经元死亡的机制,我们研究了钾离子通道在MPP⁺(1-甲基-4-苯基吡啶)诱导的野生型及α-synuclein转基因SH-SY5Y细胞死亡中的作用。方法MPP⁺孵育野生型及转染A53T突变型α-synuclein基因的SH-SY5Y细胞,或提前孵育钾离子通道抑制剂,全细胞膜片钳技术观察钾电流的改变。结果①MPP⁺可以诱导野生型及转染α-synuclein基因的SH-SY5Y细胞中延迟整流钾电流I_K(DR)]的增加,并且在α-synuclein转基因细胞中I_K(DR)的增加更显著;②MPP⁺孵育野生型及转染α-synuclein的SH-SY5Y细胞6h即可诱导Ik电流的增加,24～48h Ik电流增加加剧;③四乙铵(TEA)可以抑制MPP⁺诱导的野生型和α-synuclein转基因SH-SY5Y细胞中钾电流的增加。结论钾离子通道的开放及延迟整流钾电流的增加在MPP⁺诱导的帕金森氏病细胞模型中发挥重要作用,为揭示PD中多巴胺能神经元的凋亡提供了新的思路。

Role of Potassium Channels in MPP+-induced Apoptosis in Alpha-Synuclein Transfected Cells

OBJECTIVE To investigate the alteration of delayed rectifier potassium current in MPP⁺-induced cell death in wild type(WT) and alpha-synuclein transfected SH-SY5Y cells. METHODS Wild type and A53T mutant alpha-synuclein transfected SH-SY5Y were exposed to MPP⁺ (1-methyl-4-phenylpyridinium) in the presence or absence of potassium channel inhibitors. Alteration of potassium currents was detected by whole-cell patch clamp technique. RESULTS MPP⁺ (500 μmol·L^-1) induced the augmentation of I_K(DR) in WT and alpha-synuclein transfected SH-SY5Y. Elevation of I_K(DR) occurred at 6 h after the incubation of MPP⁺. After 48 h of MPP⁺ incubation,I_K(DR) in alpha-synuclein transfected cells exhibited more evident augmentation compared with WT SH-SY5Y. The current density of I_K(DR) in WT SH-SY5Y was increased by 41.5%,while the current density of alpha-synuclein transfected SH-SY5Y was elevated by 99.8% in comparison with that at 0 h of MPP⁺ incubation. And the elevation of I_K(DR) induced by MPP⁺ in both two cell lines was inhibited by the pretreatment of 2.5 mmol·L^-1 TEA (tetraethylammonium). CONCLUSION Our findings that I_K(DR) was augmented in WT and alpha-synuclein transfected cells and TEA can counteract the current augmentation of current induced by MPP⁺ suggested that K⁺ efflux plays a significant role in the pathogenesis of PD and potassium channel blockers may cast a light for PD therapy.