Chloroplast to Nucleus Signaling by use of Tetrapyrroles

描述(由申请人提供)： 从细胞器到细胞核的逆行信号是细胞信号网络的重要组成部分，与细胞衰老和肿瘤进展有关。这项工作计划通过研究植物叶绿体如何向细胞核发送信号来更深入地了解这些信号通路。最近的研究表明，在叶绿体中合成的叶绿素中间体原卟啉IX和镁原卟啉IX是至少两条调控细胞核基因表达的不同途径的信号输入(分别是光敏色素和GUN信号通路)。以开花植物拟南芥为模型系统，本研究将结合遗传学、分子和生物化学方法来完成以下具体目标：(1)阐明镁原卟啉IX在叶绿体中积累调控核基因表达的机制(S)；(2)确定原卟啉IX在光敏色素信号转导中的作用及其如何调节核基因表达。拟议项目的完成将有助于理解细胞内信号、细胞器通讯，以及代谢途径和光如何调节基因表达。

DESCRIPTION (provided by applicant): Retrograde signaling from organelles to the nucleus is an important part of the cellular signaling network and has been implicated in cell aging and tumor progression. This work plans to achieve a deeper understanding of these signaling pathways by investigating how plant chloroplasts send signals to the nucleus. Recently it has been shown that chlorophyll intermediates Protoporphyrin IX and Mg-Protoporphyrin IX, synthesized in the chloroplast, are signal inputs for at least two distinct pathways that regulate gene expression in the nucleus (phytochrome and GUN signaling pathways, respectively). Using the flowering plant Arabidopsis thaliana as a model system, the proposed studies will integrate genetic, molecular, as well as biochemical approaches to complete the following specific aims; (1) elucidate the mechanism(s) by which the accumulation of Mg-Protoporphyrin IX in the chloroplast regulates gene expression in the nucleus; (2) and determine the role of Protoporphyrin IX in phytochrome signaling and how its accumulation regulates nuclear gene expression. Completion of the proposed projects will contribute to the understanding of intracellular signaling, organelle communication, and how metabolic pathways and light can regulate gene expression.