Function of Photobodies in Plant Light Signaling

摘要 如何在功能上和动态上组织细胞核是理解基本原理的核心问题 包括基因组组织和转录调控在内的细胞过程。两种动物的间期 植物核包含形态不同的、非膜结合的亚核细胞器，这些细胞器是 统称为核物体。尽管越来越多的证据表明，核物体在 在基因调控中的作用以及核体的形态和组成的变化 与疾病相关的核体生物发生的精确功能和调控机制 转录调控仍然知之甚少。一个主要的挑战是缺乏遗传模型。 在细胞信号转录调控的背景下描述核体的功能 小路。PI实验室的长期目标是利用包含光感受器的光体， 拟南芥光敏亚核结构域和光信号作为遗传模型来阐明 核体在细胞信号和转录调控中的作用。目前的数据支持中央银行 假设光体是基因调节中心，其中光响应基因的子集受 一种将基因激活与转录因子降解相结合的反式激活机制。这 该假说是在Pi以前对两个新LIGH进行的分子遗传学研究的基础上提出的 光体生物发生所需的信号组件，名为HEmera和Hermes，以及在 初步结果显示，光响应基因的一个子集在空间上定位于光体。这里 PI计划通过以下具体目标来检验这一中心假设：(1)确定光体- (2)确定Hermes的作用 在光体的功能和生物发生中的作用；(3)确定基因组的组织机制 光体。这项拟议的研究具有创新性，因为它利用了光体和光感受器 拟南芥信号作为研究核组织神秘机制的遗传模型-- 核体在基因组组织和转录调控中的功能和生物发生。这个 拟议中的研究意义重大，因为它有望揭示连接核体的新机制 生物发生和转录调控的特定机制。因为基因的基本机制 调节在植物、真菌和动物中是保守的，更好地理解光体在 拟南芥将有助于理解基因组组织的进化保守原则 和转录调控，从而最终将增强我们对它们在 人类疾病。

Abstract How the cell nucleus is functionally and dynamically organized is a central question to understanding basic cellular processes including genome organization and transcriptional regulation. The interphase of both animal and plant nuclei contain morphologically distinct, non-membrane-bounded subnuclear organelles that are collectively called nuclear bodies. Although accumulating evidence suggests that nuclear bodies play important roles in gene regulation and changes in the morphology and constitution of nuclear bodies have been associated with diseases, the precise function and regulatory mechanisms of nuclear body biogenesis in transcriptional regulation remain poorly understood. One major challenge has been the lack of genetic models to delineate the functions of nuclear bodies in the context of transcriptional regulation by cell signaling pathways. The long-term goal of the PI's laboratory is to utilize the photobody – a photoreceptor-containing, photosensory subnuclear domain – and light signaling in Arabidopsis as a genetic model to elucidate the function of nuclear bodies in cell signaling and transcriptional regulation. The current data support the central hypothesis that photobodies are gene regulatory hubs where a subset of light responsive genes is regulated by a transactivation mechanism that couples gene activation with the degradation of transcription factors. This hypothesis has been formulated on the basis of the PI's previous molecular genetic studies on two novel light signaling components required for photobody biogenesis, named HEMERA and HERMES, and on the preliminary result showing that a subset of light-responsive genes are spatially positioned to photobodies. Here the PI plans to test this central hypothesis by the following specific aims: (1) Determine the photobody- associated and HEMERA-mediated transcriptional activation mechanism; (2) Determine the role of HERMES in the function and biogenesis of photobodies; (3) Determine the mechanism of genome organization by photobodies. The proposed research is innovative, because it utilizes the photobody and photoreceptor signaling in Arabidopsis as a genetic model to investigate the enigmatic mechanisms of nuclear organization – the function and biogenesis of nuclear bodies in genome organization and transcriptional regulation. The proposed research is significant, because it is expected to uncover novel mechanisms linking nuclear body biogenesis and specific mechanisms of transcriptional regulation. Because basic mechanisms of gene regulation are conserved in plants, fungi, and animals, a better understanding of the function of photobodies in Arabidopsis will contribute to understanding of the evolutionarily conserved principles of genome organization and transcriptional regulation and thus will ultimately enhance our understanding of their misregulation in human diseases.