Study of chloroplast stromules during PCD and inter-organellar communication

描述(申请人提供)：在动物和植物中，需要各种类型的程序性细胞死亡(PCD)来移除正在死亡、感染或不再需要的细胞。植物的先天免疫依赖于一种特殊类型的PCD，称为过敏性反应(HR-PCD)，以限制病原体和预防疾病。HR-PCD的激活和执行需要快速的细胞重新编程和细胞内不同隔室之间的协调。有趣的是，我们的结果表明，在HR-PCD期间，叶绿体发出高度动态的管状延伸，称为“基质”，物理上将叶绿体连接到细胞核，可能加强它们之间的沟通。人们对球茎形成所需的细胞机制或球茎在任何生物过程中的确切功能知之甚少。这项研究的具体目标是：1)采用候选、遗传学和蛋白质组学方法来确定球茎诱导所需的新因子，并阐明它们在HR-PCD和先天免疫中的生物学作用。2)在HR-PCD过程中，球茎在产生和传播促细胞死亡信号(如过氧化氢和水杨酸)中的作用将被揭示。3)利用先进的显微技术深入研究叶绿体到核的联系，将有助于阐明细胞器间的通讯在HR-PCD和先天免疫中的重要性。本文概述的研究无疑将推动先天性免疫领域的发展，为研究人员提供一种新颖的、具有凝聚力的HR-PCD模型，该模型集成了叶绿体、线粒体和细胞核的基本功能，以及它们如何沟通以协调导致HR-PCD和先天性免疫的细胞重新编程。此外，这些研究将揭示跳动在PCD和细胞器间交流中的作用的更广泛的见解。类似于在多个模型系统中的研究，如人类细胞系、线虫、果蝇和酵母，都增加了我们对PCD的理解，拟议中的植物研究将增加对平衡细胞生死的保守和分歧机制的新见解。

DESCRIPTION (provided by applicant): In both animals and plants, various types of programmed cell death (PCD) are required for the removal of cells that are dying, infected or no longer needed. Plant innate immunity relies on a specialized type of PCD called the hypersensitive response (HR-PCD) to restrict pathogens and prevent disease. Activation and execution of HR-PCD requires rapid cellular reprogramming and the coordination between different compartments within the cell. Interestingly, our results indicate that during HR-PCD, chloroplasts send out highly dynamic tubular extensions called "stromules" that physically connect chloroplasts to nuclei, possibly augmenting their communication. Very little is known about the cellular machinery required for stromule formation or the precise function of stromules during any biological process. The specific aims of the proposed research here will 1) employ candidate, genetic and proteomic approaches to identify novel factors required for stromule induction and will elucidate their biological role during HR-PCD and innate immunity. 2) The function of stromules during the generation and propagation of pro-cell death signals, such as hydrogen peroxide and salicylic acid, during HR-PCD will be revealed. 3) An in-depth study of chloroplast-to-nuclear associations using advanced microscopy techniques will shed light on the importance of inter-organellar communication during HR-PCD and innate immunity. The research outlined here will undoubtedly advance the field of innate immunity by providing researchers with a novel, cohesive model for HR-PCD that integrates the essential functions of chloroplasts, mitochondria and nuclei, and how they communicate to coordinate cellular reprogramming that leads to HR-PCD and innate immunity. Furthermore, these studies will reveal broader insights into the role of stromules in PCD and inter-organellar communication. Similar to how studies in multiple model systems, such as human cell lines, C. elegans, Drosophila and yeast, have all added to our understanding of PCD, the proposed studies here in plants will add new insight into conserved and divergent mechanisms that balance the life and death of a cell.