胞外ATP对胡杨细胞囊泡运输的影响

Effect of eATP on vesicular trafficking in Populus euphratica cells

在植物中,胞外ATP(eATP)作为一种重要的信号分子,调控植物的生长、发育及逆境响应等多种生命活动。这些植物细胞的生命活动与囊泡运输密切相关,然而,eATP是否对植物细胞的囊泡运输具有调控作用尚不清楚。本文利用能够标记囊泡运输的荧光染料FM1-43研究了eATP对胡杨细胞囊泡运输的影响。FM1-43染色结果显示,50μmol/L eATP对胡杨细胞胞吞作用不明显,而高浓度的eATP(200、400μmol/L)则会抑制其胞吞作用,其抑制作用与eATP浓度呈正相关。高浓度的eATP(200、400μmol/L)同样抑制胡杨细胞胞吐作用。而不同浓度的ADP(50、200、400μmol/L)处理则对胡杨细胞囊泡运输无明显影响。这说明高浓度eATP对胡杨细胞囊泡运输的抑制作用不是源于eATP的水解产物,而是来自于其本身的信号作用。药理学实验发现,ATP受体抑制剂PPADS(100μmol/L)能抑制高浓度eATP对胡杨细胞囊泡运输的限制作用,说明eATP是通过嘌呤受体介导的信号通路调控囊泡运输过程。但值得注意的是,嘌呤受体的另一种抑制剂suramin(100μmol/L)却对eATP的抑制作用不明显,因为suramin处理胡杨细胞后eATP(200μmol/L)仍能抑制囊泡运输。这说明在胡杨细胞中某一类与P2X同源的受体介导了高浓度eATP对囊泡运输的抑制作用。综上,eATP作为信号分子可调控胡杨细胞的囊泡运输,并且高浓度eATP对胡杨细胞的囊泡运输具有负调控作用。

Being as a significant signal molecule,extracellular ATP（ e ATP） participates in the processes of plant growth, development and stress responses. These processes are shown to be associated with vesicular trafficking,however,the function of e ATP on vesicular trafficking is not yet clear. Here,we explored the effect of e ATP on vesicular trafficking in Populus euphratica cells using FM1-43,a selective fluorescent dye for membrane binding. FM1-43 staining revealed that 50 μmol / L e ATP had no obvious effect on endocytosis in P. euphratica cells. However,the endocytosis was inhibited by higher dosages of e ATP（ 200,400 μmol / L）,and the inhibition effect was associated with increasing e ATP concentrations.Moreover,high dosages of e ATP（ 200,400 μmol / L） also inhibited exocytosis in P. euphratica cells. In contrast to e ATP,ADP（ 50,200,400 μmol / L） did not exert a significant impact on vesicular trafficking. This suggests that the inhibitory effect of high concentrations of e ATP was not caused by the hydrolyzing product of e ATP. Pharmacological experiments showed that the ATP receptor inhibitor,PPADS（ 100 μmol / L）,could block the inhibitory effect of high e ATP on vesicular trafficking. We conclude that e ATP suppresses vesicular trafficking by a purine receptor-mediated signal pathway.However,another purine receptor inhibitor,suramin（ 100 μmol / L）,has no obvious inhibitory effect on e ATP signaling. Thus it could be inferred that other kinds of P2 X cognate receptors mediate inhibitory effect of high e ATP on vesicular trafficking. Collectively,e ATP can regulate vesicular trafficking in P.euphratica cells,but high concentrations of e ATP display a negative regulation on vesicular trafficking.