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传导是细胞信号传导网络的重要组成部分，并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，它已被证明，叶绿素中间体原卟啉IX和镁-原卟啉IX，在叶绿体中合成，是至少两个不同的途径，调节基因在细胞核中的表达（光敏色素和GUN信号通路，分别）的信号输入。本研究以开花植物拟南芥为模型系统，综合运用遗传学、分子生物学和生物化学方法，旨在实现以下具体目标：（1）阐明Mg-原卟啉IX在叶绿体中的积累对核基因表达的调控机制;（2）确定原卟啉IX在光敏色素信号传导中的作用及其积累如何调节核基因表达。完成拟议的项目将有助于理解细胞内信号，细胞器通信，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.