Cellular Mecanisms Controlling CDPK-Mediated Auxin Signaling Pathway

植物钙依赖性蛋白激酶（CDPKs）具有钙感受器和钙效应器的双重功能，被认为参与细胞对内外刺激的多种反应。 然而，它们精确的生理功能仍然难以捉摸。 利用基于原生质体的功能基因组学方法和基于RNA干扰的反向遗传学技术，首次发现了拟南芥中两个CDPKs在生长素信号转导中的新功能，为Ca 2+信号转导与生长素的作用提供了分子证据。CDPK双敲除突变体显示出严重的分生组织缺陷，抑制几个关键的分生组织调节因子，并在整个植物生命周期中表现出异常生长。 基于这些结果，我们假设这两个CDPKs代表了生长素和Ca 2+信号传导与发育过程之间的“缺失环节”。本研究的长期目标是了解CDPK介导的生长素信号转导途径的机制和意义。 这些数据将表明，生长素刺激后，CDPK从质膜到胞质溶胶的快速移动是CDPK依赖的生长素信号传导的关键步骤。 本项目的目的是确定和表征细胞机制控制生长素依赖的CDPK易位。拟议的实验将使用功能测定与生长素响应报告在原生质体和幼苗，结合荧光蛋白为基础的生物成像，以建立CDPK介导的生长素信号转导是否涉及蛋白质脂质修饰，磷酸化，囊泡运输，和/或细胞骨架重塑。

Plant calcium-dependent protein kinases (CDPKs) have dual functions as calcium sensors and effectors, and are thought to be involved in multiple cellular responses to external and internal stimuli. However, their precise physiological functions remain elusive. Using a protoplast based functional genomics approach and RNA interference based reverse genetics, a novel function of two Arabidopsis CDPKs in auxin signaling was discovered, providing the first molecular evidence connecting Ca2+ signaling to the action of auxin. A CDPK double knockout mutant shows severe meristem defects, repression of several key meristem regulators, and exhibits abnormal growth throughout the plant life cycle. Based on these results, it is hypothesized that these two CDPKs represent a "missing link" between auxin and Ca2+ signaling, and developmental processes. The long-term goal of this research project is to understand the mechanisms and significance of the CDPK-mediated auxin signal transduction pathway. The data will show that a rapid movement of CDPK from the plasma membrane to the cytosol upon auxin stimulation is a crucial step for CDPK-dependent auxin signaling. The objective of this project is to identify and characterize cellular mechanisms controlling auxin-dependent CDPK translocation. The proposed experiments will use functional assays with an auxin-responsive reporter in both protoplasts and seedlings, combined with fluorescent-protein based bio-imaging to establish if CDPK-mediated auxin signaling involves protein lipid modification, phosphorylation, vesicle trafficking, and/or cytoskeleton remodeling.