胞外ATP对胡杨细胞囊泡运输的影响

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,50 mol/L eATP对胡杨细胞胞吞作用不明显,而高浓度的eATP(200、400 mol/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、400 mol/L)同样抑制胡杨细胞胞吐作用。而不同浓度的ADP(50、200、400 mol/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(100 mol/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(100 mol/L)却对eATP的抑制作用不明显,因为suramin处理胡杨细胞后eATP(200 mol/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。 

Effect of eATP on vesicular trafficking in Populus euphratica cells

Being as a significant signal molecule, extracellular ATP ( eATP) 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 eATP on vesicular trafficking is not yet clear. Here, we explored the effect of eATP 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 eATP had no obvious effect on endocytosis in P. euphratica cells. However, the endocytosis was inhibited by higher dosages of eATP (200, 400μmol/L), and the inhibition effect was associated with increasing eATP concentrations. Moreover, high dosages of eATP (200, 400μmol/L) also inhibited exocytosis in P. euphratica cells. In contrast to eATP, 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 eATP was not caused by the hydrolyzing product of eATP. Pharmacological experiments showed that the ATP receptor inhibitor, PPADS ( 100 μmol/L ) , could block the inhibitory effect of high eATP on vesicular trafficking. We conclude that eATP suppresses vesicular trafficking by a purine receptor-mediated signal pathway. However, another purine receptor inhibitor, suramin (100μmol/L) , has no obvious inhibitory effect on eATP signaling. Thus it could be inferred that other kinds of P2X cognate receptors mediate inhibitory effect of high eATP on vesicular trafficking. Collectively, eATP can regulate vesicular trafficking in P. euphratica cells, but high concentrations of eATP display a negative regulation on vesicular trafficking.