Genetic characterization of phytochrome nuclear bodies in plant light signaling

植物光信号传导中光敏色素核体的遗传特征

• 批准号: 8324310
• 负责人: Meng Chen
• 金额: $ 37.24万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8324310
• 关键词: Acute Promyelocytic Leukemia; Alleles; Animals; Arabidopsis; Binding; Binding Proteins; Biochemical; Biological; Biological Models; Cell Nucleus; Cells; Complement; Complex; Constitution; Coupled; Cytoplasm; Cytoplasmic Granules; Event; Genes; Genetic; Genetic Models; Genetic Screening; Genetic Transcription; Goals; In Vitro; Light; Link; Maps; Mediating; Modeling; Molecular; Morphology; Nuclear; Orthologous Gene; Pattern; Photoreceptors; Phototransduction; Physiological Processes; Phytochrome; Plants; Property; Proteasome Binding; Proteolysis; Regulation; Research; Role; Seedling; Series; Signal Transduction; Signal Transduction Pathway; Site; System; Testing; Transcriptional Regulation; Yeasts; base; body system; human disease; insight; multicatalytic endopeptidase complex; mutant; novel; phyB phytochrome; plant growth/development; protein degradation; public health relevance; receptor; research study; response; tool; yeast protein

DESCRIPTION (provided by applicant): Nuclear bodies (NBs) are distinct subnuclear domains present in both animal and plant cells. Although numerous NBs, such as Cajal bodies, PML (promyelocytic leukemia) NBs , and IGC (interchromatin granule cluster) have been extensively studied in mammalian systems, and changes in morphology and constitution of these nuclear bodies are associated with human diseases, the precise function and regulation of NBs are still poorly understood. One possible reason for this is the lack of genetic models to study NB functions. We propose to use phytochrome NBs in plant light signaling as a genetic model system to investigate general principles behind NB functions. Phytochromes are red and far-red photoreceptors regulating plant development and growth through transcription regulation. Phytochromes localize in the cytoplasm in the dark. Upon light activation, they relocate to the nucleus and form phytochrome NBs. We demonstrated that the formation of a photo-stable phytochrome B (PHYB) containing NBs is directly regulated by light and is tightly correlated to phytochrome responses. Based on these observations, we hypothesize that phytochrome NBs are directly involved in phytochrome signaling events. To test this hypothesis, we propose to: (1) identify and characterize new components required for PHYB-GFP NB formation by a confocal-based genetic screen. We have already identified twenty-nine such mutants. One locus, HMR, has been cloned, and two others rough-mapped. Strikingly, our preliminary studies show that the first gene (HMR) identified from this screen is required for both PHYB-GFP NB formation and early phytochrome signaling events including the light-dependent proteolysis of PHYA, a photo-labile phytochrome. Interestingly, HMR is structurally similar to the mammalian ortholog of a yeast protein RAD23, which is a multiubiquitin binding protein involved in protein degradation. These results provide the first genetic evidence linking phytochrome nuclear bodies with protein degradation, and demonstrate that this genetic screen will likely identify novel components linking phytochrome NB function and early phytochrome signaling events; (2) investigate the function of phytochrome NBs in early phytochrome signaling events. We propose a number of experiments to directly test whether phytochrome NBs are sites for PHYA degradation and/or transcription regulation; (3) define the function of HMR in PHYA degradation. We will test whether HMR acts as RAD23 by delivering PHYA to the proteasome for degradation. Collectively, the proposed experiments should contribute significantly to a better understanding of light signaling in plants. More importantly, they will also start to unravel general principles of NBs in cell signaling. PUBLIC HEALTH RELEVANCE: Nuclear bodies are distinct subnuclear domains present in both animal and plant systems. Changes in morphology and constitution of numerous mammalian nuclear bodies are associated with human diseases. We will take advantage of the plant phytochrome nuclear body system and use it as a genetic model to investigate the function and regulation of nuclear bodies in the context of cell signaling. Our studies should contribute significantly to our understanding of the cellular and molecular basis for human diseases.

描述（由申请人提供）：核体（NB）是动物和植物细胞中存在的不同下核域。尽管许多NB，例如Cajal身体，PML（Promyelocytic Leukemia）NBS和IGC（IGC（染色质颗粒簇）），在哺乳动物系统中已经进行了广泛的研究，并且这些核体的形态和构成的变化与人类疾病的形态和构成有关，与人类疾病，人类疾病，精确的nbs nbs相关。造成这种情况的一个可能原因是缺乏研究NB功能的遗传模型。我们建议在植物光信号中使用植物色素NB作为遗传模型系统，以研究NB功能背后的一般原理。植物色素是红色和远红感受器，可通过转录调节调节植物的发育和生长。植物色素定位在黑暗中的细胞质中。光激活后，它们迁移到核并形成植物色素NB。我们证明了含有NB的光稳定植物色素B（Phyb）的形成直接受光调节，并且与植物色素反应密切相关。基于这些观察结果，我们假设植物色素NB直接参与植物色素信号事件。为了检验这一假设，我们建议：（1）通过基于共聚焦的遗传筛选确定并表征Phyb-GFP NB形成所需的新组件。我们已经确定了29个这样的突变体。一个基因座HMR被克隆了，另外两个基因座进行了粗图形。令人惊讶的是，我们的初步研究表明，从该筛选中鉴定出的第一个基因（HMR）是Phyb-GFP NB形成和早期植物色素信号事件所必需的，包括光含光含量的phya的光依赖性蛋白水解。有趣的是，HMR在结构上与酵母蛋白RAD23的哺乳动物直系同源物相似，该酵母蛋白RAD23是一种参与蛋白质降解的多泛素结合蛋白。这些结果提供了将植物色素核体与蛋白质降解联系起来的第一个遗传证据，并证明该遗传筛查可能会识别连接植物色素NB功能和早期植物色素信号事件的新成分； （2）研究植物色素NB在早期植物色素信号事件中的功能。我们提出了许多实验，以直接测试植物色素NBS是否是phya降解和/或转录调控的部位； （3）定义HMR在PHYA降解中的功能。我们将通过向蛋白酶体传递PHYA来降解HMR是否充当RAD23。总的来说，提出的实验应显着有助于更好地理解植物中的光信号传导。更重要的是，它们还将开始阐明细胞信号传导中NBS的一般原则。 公共卫生相关性：核体是动物和植物系统中存在的不同的亚核域。众多哺乳动物核体的形态和宪法的变化与人类疾病有关。我们将利用植物植物色素核体系统，并将其用作遗传模型，以研究细胞信号传导中核体的功能和调节。我们的研究应为我们对人类疾病的细胞和分子基础的理解做出重大贡献。