Wang Limin, Stacey Gary, Leblanc-Fournier Nathalie, Legué Valérie, Moulia Bruno, Davies Julia M
Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
Divisions of Plant Science and Biochemistry, University of Missouri, Columbia, MO, United States.
Front Plant Sci. 2019 Sep 4;10:1064. doi: 10.3389/fpls.2019.01064. eCollection 2019.
Adenosine 5'-triphosphate (ATP) is an important extracellular signaling agent, operating in growth regulation, stomatal conductance, and wound response. With the first receptor for extracellular ATP now identified in plants (P2K1/DORN1) and a plasma membrane NADPH oxidase revealed as its target, the search continues for the components of the signaling cascades they command. The root elongation zone epidermal plasma membrane has recently been shown to contain cation transport pathways (channel conductances) that operate downstream of P2K1 and could contribute to extracellular ATP (eATP) signaling. Here, patch clamp electrophysiology has been used to delineate two further conductances from the root elongation zone epidermal plasma membrane that respond to eATP, including one that would permit chloride transport. This perspective addresses how these conductances compare to those previously characterized in roots and how they might operate together to enable early events in eATP signaling, including elevation of cytosolic-free calcium as a second messenger. The role of the reactive oxygen species (ROS) that could arise from eATP's activation of NADPH oxidases is considered in a qualitative model that also considers the regulation of plasma membrane potential by the concerted action of the various cation and anion conductances. The molecular identities of the channel conductances in eATP signaling remain enigmatic but may yet be found in the multigene families of glutamate receptor-like channels, cyclic nucleotide-gated channels, annexins, and aluminum-activated malate transporters.
腺苷 5'-三磷酸（ATP）是一种重要的细胞外信号传导因子，在生长调节、气孔导度和伤口反应中发挥作用。随着植物中首个细胞外 ATP 受体（P2K1/DORN1）的确定以及质膜 NADPH 氧化酶被揭示为其作用靶点，对它们所调控的信号级联反应的组成成分的探索仍在继续。最近研究表明，根伸长区表皮质膜含有在 P2K1 下游起作用的阳离子转运途径（通道电导），可能参与细胞外 ATP（eATP）信号传导。在这里，膜片钳电生理学已被用于从根伸长区表皮质膜中描绘出另外两种对 eATP 有反应的电导，其中一种允许氯离子转运。本文探讨了这些电导与先前在根中所表征的电导如何比较，以及它们如何共同作用以促成 eATP 信号传导的早期事件，包括将胞质游离钙作为第二信使升高。在一个定性模型中考虑了 eATP 激活 NADPH 氧化酶可能产生的活性氧（ROS）的作用，该模型还考虑了各种阳离子和阴离子电导协同作用对质膜电位的调节。eATP 信号传导中通道电导的分子身份仍然不明，但可能在谷氨酸受体样通道、环核苷酸门控通道、膜联蛋白和铝激活苹果酸转运体的多基因家族中找到。
