Extracellular Nucleotides Elicit Cytosolic Free Calcium Oscillations in Arabidopsis
Extracellular Nucleotides Elicit Cytosolic Free Calcium Oscillations in Arabidopsis
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DOI：
10.1104/pp.110.162503
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发表时间：
2010-10-01
期刊：
影响因子：
7.4
通讯作者：
Stacey, Gary
中科院分区：
文献类型：
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作者：
Tanaka, Kiwamu;Swanson, Sarah J.;Stacey, Gary
细胞外ATP诱导植物细胞内游离钙（[Ca ~（2+）]（cyt））水平升高。为了扩大我们对植物细胞外核苷酸功能的了解，使用表达水母发光蛋白的转基因拟南芥（Arabidopsis thaliana）或基于荧光共振能量转移的Ca 2+传感器Yellow Cameleon 3.6研究了几种核苷酸类似物和药理学试剂对[Ca 2 +]（cyt）变化的影响。与嘌呤核苷酸ATP和GTP相比，外源性CTP引起[Ca 2 +]（cyt）升高，显示出不同的时间和剂量依赖性动力学。哺乳动物P2受体拮抗剂和钙内流抑制剂对核苷酸诱导的[Ca ~（2+）]（cyt）升高的抑制作用在CTP和嘌呤核苷酸之间是不同的。这些结果表明，不同的识别系统可能存在各自类型的核苷酸。有趣的是，与野生型相比，缺乏异源三聚体G蛋白G β亚基的突变体在响应所有测试的核苷酸时表现出显著更高的[Ca 2 +]（cyt）升高。这些数据表明G β在负调节细胞外核苷酸信号传导中的作用，并指出异源三聚体G蛋白在调节细胞外核苷酸的细胞效应中的重要作用。此外，细胞外核苷酸诱导多个时间[Ca 2 +]（细胞色素）振荡，这可以定位到特定的根细胞。振荡衰减的囊泡运输抑制剂，表明振荡可能需要ATP释放通过胞吐分泌。这些结果揭示了关于植物细胞外核苷酸信号传导的新的分子细节，以及精细控制细胞外核苷酸水平以介导特定植物细胞反应的重要性。
Extracellular ATP induces a rise in the level of cytosolic free calcium ([Ca2+](cyt)) in plant cells. To expand our knowledge about the function of extracellular nucleotides in plants, the effects of several nucleotide analogs and pharmacological agents on [Ca2+](cyt) changes were studied using transgenic Arabidopsis (Arabidopsis thaliana) expressing aequorin or the fluorescence resonance energy transfer-based Ca2+ sensor Yellow Cameleon 3.6. Exogenously applied CTP caused elevations in [Ca2+](cyt) that displayed distinct time-and dose-dependent kinetics compared with the purine nucleotides ATP and GTP. The inhibitory effects of antagonists of mammalian P2 receptors and calcium influx inhibitors on nucleotide-induced [Ca2+](cyt) elevations were distinct between CTP and purine nucleotides. These results suggest that distinct recognition systems may exist for the respective types of nucleotides. Interestingly, a mutant lacking the heterotrimeric G protein G beta-subunit exhibited a remarkably higher [Ca2+](cyt) elevation in response to all tested nucleotides in comparison with the wild type. These data suggest a role for G beta in negatively regulating extracellular nucleotide signaling and point to an important role for heterotrimeric G proteins in modulating the cellular effects of extracellular nucleotides. The addition of extracellular nucleotides induced multiple temporal [Ca2+](cyt) oscillations, which could be localized to specific root cells. The oscillations were attenuated by a vesicle-trafficking inhibitor, indicating that the oscillations likely require ATP release via exocytotic secretion. The results reveal new molecular details concerning extracellular nucleotide signaling in plants and the importance of fine control of extracellular nucleotide levels to mediate specific plant cell responses.