Stress Hormone Signal Transduction in Arabidopsis

拟南芥中的应激激素信号转导

• 批准号: 7243020
• 负责人: JULIAN I SCHROEDER
• 金额: $ 1.37万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7243020
• 关键词: Arabidopsis; alkyltransferase; biological signal transduction; calcium channel; calcium flux; calcium indicator; cell growth regulation; cell membrane; cell proliferation; cytoplasm; eukaryote; gene deletion mutation; genetic library; hormone regulation /control mechanism; intracellular transport; molecular cloning; molecular dynamics; mutant; phosphomonoesterases; phytohormones; plant growth /development; protein structure function; second messengers; stress proteins; water channel

DESCRIPTION (provided by applicant): Abscisic acid is a central stress hormone in plants which mediates rapid cellular responses, down regulates cell proliferation, causes cell cycle arrest and inhibits growth. Signal transduction mechanisms that down regulate cell proliferation are of central importance for controlling mitogenesis. Abscisic acid (ABA) signal transduction will be investigated in Arabidopsis guard cells, which have been developed as a powerful molecular genetic, genomic and time-resolved signaling system for quantitatively dissecting the complex molecular machinery mediating specificity in early signaling cascades. We will analyze the cellular mechanisms of a newly revealed major early ABA signal transduction pathway. In brief, we showed that ABA causes rapid production of reactive oxygen species (ROS) in guard cells, which in turn activate plasma membrane calcium (Ca2+) channels. This produces a defined window of Ca2+ oscillation parameters that are required for ABA signal transduction. We identified ABA signaling mutants that function at distinct points in the newly recognized ABA-ROS-Ca2+. oscillation signaling pathway, including mutations in the NADPH oxidase genes AtrbohD &F, PP2C phosphatases and the mRNA cap binding protein ABH1. We will test the hypotheses: that ABA biochemically activates membrane NADPH oxidases causing ROS production; that negatively regulating Ca2+ sensors function in reading specific Ca2+ oscillations; and that abh1 amplifies ABA-induced Ca2+ oscillations due to mRNA processing of early ABA signal transducers. To address these hypotheses, we will pursue the following specific aims: (1) Characterize biochemical and molecular mechanisms mediating rapid ABA-induced ROS production and characterize proteins complexed with the abi1-1 PP2C. (2) Analyze mechanisms by which ROS activate Ca2+ channels and isolate the Ca2+ channel genes. (3) The mechanisms responsible for reading specific calcium oscillations remain largely unknown in eukaryotes. Characterize the roles of the TCH2 and CalcineurinB-AtCBL Ca2+ sensory proteins in reading Ca2+ oscillations. (4) Characterize the mechanisms by which the abh1 mRNA cap binding mutant amplifies ABA-induced Ca2+ oscillations. A new virus-induced gene silencing-based screen will be pursued for identifying novel redundant ABA signaling mutants. These studies will reveal important fundamental mechanisms by which a newly recognized early signaling pathway controls ABA stress signal transduction and will contribute to a general understanding of Ca2+ signaling specificity in eukaryotes.

描述（由申请人提供）：脱落酸是植物中的主要应激激素，其介导快速细胞反应、下调细胞增殖、引起细胞周期停滞并抑制生长。下调细胞增殖的信号转导机制对于控制有丝分裂至关重要。脱落酸（ABA）信号转导将在拟南芥保卫细胞中进行研究，该细胞已被开发为强大的分子遗传、基因组和时间分辨信号系统，用于定量剖析早期信号级联中介导特异性的复杂分子机制。我们将分析新发现的主要早期 ABA 信号转导途径的细胞机制。简而言之，我们发现 ABA 会导致保卫细胞中活性氧 (ROS) 的快速产生，进而激活质膜钙 (Ca2+) 通道。这会产生 ABA 信号转导所需的 Ca2+ 振荡参数的定义窗口。我们鉴定了 ABA 信号传导突变体，它们在新识别的 ABA-ROS-Ca2+ 的不同位点发挥作用。振荡信号通路，包括 NADPH 氧化酶基因 AtrbohD &F、PP2C 磷酸酶和 mRNA 帽结合蛋白 ABH1 的突变。 我们将测试以下假设：ABA 生化激活膜 NADPH 氧化酶，导致 ROS 产生；负调节 Ca2+ 传感器的功能是读取特定的 Ca2+ 振荡；并且由于早期 ABA 信号转导器的 mRNA 处理，abh1 放大了 ABA 诱导的 Ca2+ 振荡。为了解决这些假设，我们将追求以下具体目标：（1）表征介导 ABA 诱导的 ROS 快速产生的生化和分子机制，并表征与 abi1-1 PP2C 复合的蛋白质。 (2)分析ROS激活Ca2+通道的机制并分离Ca2+通道基因。 (3) 真核生物中负责读取特定钙振荡的机制仍然很大程度上未知。描述 TCH2 和 CalcineurinB-AtCBL Ca2+ 感觉蛋白在读取 Ca2+ 振荡中的作用。 (4) 描述 abh1 mRNA cap 结合突变体放大 ABA 诱导的 Ca2+ 振荡的机制。将寻求一种新的基于病毒诱导的基因沉默的筛选，以鉴定新的冗余 ABA 信号突变体。这些研究将揭示新认识的早期信号通路控制 ABA 应激信号转导的重要基本机制，并将有助于对真核生物中 Ca2+ 信号传导特异性的一般理解。