Nicolaus Copernicus University, Faculty of Biology and Environmental Protection, Chair of Plant Physiology and Biotechnology, Lwowska St. 1, PL 87-100 Torun, Poland.
J Plant Physiol. 2019 Oct;241:153035. doi: 10.1016/j.jplph.2019.153035. Epub 2019 Aug 27.
Cell signaling is an evolutionarily conserved mechanism that responds and adapts to various internal and external factors. Generally, a signal is mediated by various signaling molecules and is transferred to a cascade of effector proteins. To date, there is significant evidence that cyclic nucleotides (cNMPs), e.g., adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP), may represent important elements of many signaling pathways in plants. However, in contrast to the impressive progress made in understanding cyclic nucleotide signaling in mammalian hosts, only few studies have investigated this topic in plants. Existing evidence indicates that cNMPs participate in growth and developmental processes, as well as the response to various stresses. Once synthesized by adenylyl or guanylyl cyclases, these signals are transduced by acting through a number of cellular effectors. The regulatory effects of cNMPs in eukaryotes can be mediated via various downstream effector proteins, such as protein kinases, Exchange Protein directly Activated by cAMP (EPAC), and Cyclic Nucleotide-Gated ion Channels (CNGC). These proteins sense changes in intracellular cNMP levels and regulate numerous cellular responses. Moreover, the amplitude of cNMP levels and the duration of its signal in the cell is also governed by phosphodiesterases (PDEs), enzymes that are responsible for the breakdown of cNMPs. Data collected in recent years strongly suggest that cyclic nucleotide gated channels are the main cNMP effectors in plant cells. These channels are important cellular switches that transduce changes in intracellular concentrations of cyclic nucleotides into changes in membrane potential and ion concentrations. Structurally, these channels belong to the superfamily of pore-loop cation channels. In this review, we provide an overview of the molecular properties of CNGC structure, regulation and ion selectivity, and subcellular localization, as well as describing the signal transduction pathways in which these channels are involved. We will also summarize recent insights into the role of CNGC proteins in plant growth, development and response to stressors.
细胞信号转导是一种进化上保守的机制，它可以响应和适应各种内部和外部因素。通常，信号由各种信号分子介导，并传递到一系列效应蛋白级联中。迄今为止，有大量证据表明，环核苷酸（cNMPs），例如 3'，5'-环腺苷酸（cAMP）和 3'，5'-环鸟苷酸（cGMP），可能代表植物中许多信号通路的重要组成部分。然而，与在哺乳动物宿主中理解环核苷酸信号方面取得的令人瞩目的进展相比，仅有少数研究调查了植物中的这个主题。现有证据表明，cNMPs 参与生长和发育过程以及对各种胁迫的反应。这些信号一旦由腺苷酸环化酶或鸟苷酸环化酶合成，就通过作用于许多细胞效应物进行转导。真核生物中 cNMP 的调节作用可以通过各种下游效应蛋白介导，如蛋白激酶、cAMP 直接激活的交换蛋白（EPAC）和环核苷酸门控离子通道（CNGC）。这些蛋白质感知细胞内 cNMP 水平的变化，并调节许多细胞反应。此外，cNMP 水平的幅度及其在细胞中的信号持续时间也受磷酸二酯酶（PDEs）的控制，PDEs 是负责 cNMP 分解的酶。近年来收集的数据强烈表明，环核苷酸门控通道是植物细胞中 cNMP 的主要效应物。这些通道是重要的细胞开关，可将细胞内 cNMP 浓度的变化转化为膜电位和离子浓度的变化。在结构上，这些通道属于孔环阳离子通道超家族。在本综述中，我们概述了 CNGC 结构、调节和离子选择性的分子特性以及亚细胞定位，并描述了这些通道参与的信号转导途径。我们还将总结最近关于 CNGC 蛋白在植物生长、发育和应对胁迫中的作用的新见解。
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