Study of chloroplast stromules during PCD and inter-organellar communication

描述（由申请人提供）：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。植物先天免疫依赖于一种特殊类型的PCD，称为超敏反应（HR-PCD）来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编程和细胞内不同区室之间的协调。有趣的是，我们的研究结果表明，在HR-PCD过程中，叶绿体发出高度动态的管状延伸，称为“间质”，将叶绿体物理连接到细胞核，可能增加了它们的通信。在任何生物过程中，我们对基质形成所需的细胞机制或基质的精确功能知之甚少。本研究的具体目标是：1)采用候选因子、遗传因子和蛋白质组学方法来鉴定基质诱导所需的新因子，并阐明它们在HR-PCD和先天免疫中的生物学作用。2)揭示基质在HR-PCD过程中过氧化氢、水杨酸等促细胞死亡信号产生和传播中的作用。3)利用先进的显微镜技术深入研究叶绿体与核的关联，将揭示HR-PCD和先天免疫过程中细胞器间通讯的重要性。这里概述的研究无疑将推动先天免疫领域的发展，为研究人员提供一个新的、有凝聚力的HR-PCD模型，该模型整合了叶绿体、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和先天免疫的细胞重编程。此外，这些研究将揭示基质在PCD和细胞间通讯中的作用。类似于在人类细胞系、秀丽隐杆线虫、果蝇和酵母等多种模型系统中的研究，都增加了我们对PCD的理解，这里提出的植物研究将为平衡细胞生与死的保守和不同机制提供新的见解。

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. PUBLIC HEALTH RELEVANCE: Inter-organellar communication is crucial for cells to coordinate the rapid cellular reprogramming that leads to the activation of programmed cell death (PCD). Plants use PCD as a defense mechanism to kill cells that are infected with potential pathogens. The study of PCD in model systems such as human cell lines, C. elegans, Drosophila and yeast, have contributed significantly towards our understanding of PCD in growth, development, defense and cancer. The proposed studies here in a plant model system will provide novel insights into conserved and divergent mechanisms that balance the life and death of a cell.