Ca^(2+)和突触融合蛋白1对突触前膜5-HT转运体转运活性的调控研究

Modulating effects of Ca^(2+) and syntaxin 1 on seronin transporter activity in the presynaptic membrane

目的:考察Ca2+和/或囊泡胞吐相关蛋白突触融合蛋白1(syntaxin 1)对5-HT转运体(SERT)转运功能的调控作用。方法:通过增加突触前膜外Ca2+水平和利用离子霉素促Ca2+内流,观察Ca2+对SERT活性和syntaxin 1/SERT复合体的影响;通过肉毒毒素C(BoNT/C)阻断syntaxin 1的作用,考察syntax-in 1对SERT转运功能的调控。结果:增加突触膜外Ca2+水平和/或促其内流将促进SERT的磷酸化,降低SERT的再摄取活性,促进蛋白激酶C(PKC)激动剂佛波酯(PMA)诱导的SERT磷酸化,降低功能性SERT/syntaxin 1复合体的水平;而BoNT/C预处理能阻断syntaxin 1的功能,显著抑制SERT的再摄取功能,减少功能性SERT/syntaxin1复合体的水平。结论:介导神经信号传递的Ca2+和调控囊泡膜融合和释放神经递质的syntaxin 1可能通过磷酸化SERT和调节SERT/syntaxin 1复合体的水平,调控SERT的再摄取活性。

Objective： To investigate the modulating effects of Ca^2＋ or/and syntaxin 1 on serotonin transporter（SERT） activity.Methods： Elevated extracellular Ca^2＋ or enhanced Ca^2＋ influx by ionomycin was used to observe effects of Ca^2＋ on SERT activity of the presynaptic membrane.Botulinus neurotoxin C（BoNT/C）,which selectively cut the connection between syntaxin 1 and plasma membrane,and interrupted synaptic vesicle release,was applied to investigate the regulating effects of syntaxin 1 on SERT activity.Results： Both elevated extracellular Ca^2＋ and enhanced Ca^2＋ influx strengthened phosphorylation of SERT threonine residue,inhibited SERT reuptake activity,facilitated PMA-induced SERT phosphorylation,and decreased functional SERT/syntaxin 1 complex.Pre-treatment with BoNT/C significantly inhibited SERT activity by interrupting the function of syntaxin 1,and decreased functional SERT/syntaxin 1 complex.Conclusion： Both Ca^2＋（mediating neural signal transmission） and syntaxin 1（regulating synaptic vesicle membrane fusion and neurotransmitter releasing） may modulate SERT uptake activity by facilitating the phosphorylation of SERT or by regulating the level of SERT/syntaxin 1 complex.