Otx1诱导外向钾电流并抑制小鼠神经母细胞瘤细胞增殖

Otx1 induces outward potassium current and inhibits mouse neuroblas⁃toma cell proliferation

目的:探讨Otx1(orthodenticle homeobox 1)蛋白在调节电压门控性钾通道中的作用,并分析其对体外培养的小鼠神经细胞增殖的影响。方法:小鼠神经母细胞瘤N2a细胞中分别转染对照和过表达Otx1的质粒DNA,应用全细胞膜片钳记录N2a细胞中K^(+)依赖的外向电流;通过电生理技术,分析Otx1对K^(+)电流激活、失活和失活后恢复时间等参数的影响;通过细胞转染Otx1突变体,研究其对细胞增殖的影响。结果:过表达Otx1可增强电压依赖性外向K^(+)电流,降低半失活电位,并延迟外向电流失活后恢复;星形胶质细胞瘤相关的Otx1突变体K321T和Y320C所诱导的K^(+)电流幅度较低,与野生型Otx1相比,转染K321T或Y320C突变体的细胞增殖率升高;在N2a细胞表达Kv4.2α也导致外向K^(+)电流增强,并抑制N2a细胞的增殖。结论:Otx1可在体外培养的小鼠神经细胞中诱导电压依赖性K^(+)电流,而K^(+)电流可能参与细胞的增殖过程。

AIM:To investigate the role of orthodenticle homeobox 1(Otx1)in the regulation of voltage-gated potassium channels and to analyze the effect of K^(+) current induced by Otx1 on the proliferation of mlouse neuroblastoma N2a cells in vitro.METHODS:The K^(+)-dependent outward currents in the N2a cells with Otx1 over-expression were de-tected by whole-cell patch-clamp technique.The effects of Otx1 on electrophysiological parameters such as K^(+) current acti-vation,inactivation and recovery time were analyzed.The proliferation of the N2a cells transfected with Otx1 over-expres-sion plasmid and its mutants was determined.RESULTS:Over-expression of Otx1 enhanced the amplitude of a voltage-dependent K^(+) current,reduced the half-inactivation potential,and delayed the recovery after the outward current inactiva-tion.Astrocytoma-related Otx1 mutants K321T and Y320C induced lower amplitude of the K^(+) current and resulted in higher cell proliferation rate as compared with the wild-type Otx1.Moreover,expression of Kv4.2αsubunit activated an outward K^(+) current and inhibited the proliferation of N2a cells.CONCLUSION:Otx1 promotes voltage-dependent K^(+) cur-rents of neural cells in vitro,and the K^(+) current may be involved in the regulation of cell proliferation.