Defining the Retrograde Plastid-to-Nucleus Stress Signaling Pathway

描述(申请人提供)：逆行信号是一种从细胞器到细胞核的通讯途径，对生物体中许多过程的调控和协调至关重要，包括发育过程、对生物和非生物挑战的反应、蛋白质运输和染色质结构的重塑。最近，我们发现了第一个应激特异性逆行胞质到核的信号代谢产物，甲基赤藓糖醇环二磷酸(MECPP)，它是由甲基赤藓糖醇磷酸(MEP)途径产生的一种异戊二烯前体。这是一条保守的信号通路，存在于植物、病原细菌和植物的非光合体“质外体”中。 疟疾寄生虫，但在动物身上不存在。我们研究的长期目标是深入了解作为植物对胁迫反应的基础的MECPP信号级联的感知和转导所涉及的调控成分。为了实现这一目标，在一项合作研究中，我们建议针对以下具体目标：1：使用遗传和生化方法定义MECPP信号通路的细胞成分。2：通过研究MECPP调节的第二类组蛋白脱乙酰酶(HDAC)，以及MECPP介导的染色质结构修饰的全球定位，确定在MECPP信号通路中调节的表观遗传调节因子。3：利用蛋白质组学和细胞生物学方法，确定胞质基质(间质充满的小管)在MECPP介导的胞质到胞核逆行信号中的作用。为了实现这些特定的目标，我们产生了基础数据和无与伦比的实验工具，包括尽管MECPP水平高，但抑制系诱导逆境反应基因的能力恢复了；基于微阵列的确认组蛋白脱乙酰酶基因是潜在的逆境反应的表观遗传调节基因；以及表达荧光蛋白的叶绿体系，这些系使得能够基于显微镜鉴定在MECPP水平增强的植物中发现的被称为“基质”的叶绿体管延伸。

DESCRIPTION (provided by applicant): Retrograde signaling is a communication pathway from organelles to nucleus central to regulation and coordination of numerous processes in living organisms, including developmental progressions, responses to biotic and abiotic challenges, protein trafficking and remodeling of chromatin structure. Recently, we have identified the first stress-specific retrograde plastid-to-nucleus signaling metabolite, methylerythritol cyclodiphosphate (MEcPP), an isoprenoid precursor produced by the methylerythritol phosphate (MEP) pathway. This is a conserved signaling pathway that is present in plants, pathogenic bacteria, and in the non- photosynthetic plastids "apicoplast" of the malarial parasite, but is absent in animals. The long-term goal of our research is to gain insight into the regulatory components involved in perception and transduction of the MEcPP signaling cascade that underlies plant responses to stress. Towards this goal, in a collaborative study, we propose to target the following specific objectives: 1: Define cellular components of the MEcPP signaling pathway using genetic and biochemical approaches. 2: Define epigenetic regulators modulated during MEcPP signaling pathway by studying MEcPP regulated class II histone deacetylase (HDAC), and by global mapping of MEcPP-mediated chromatin structural modifications. 3: Determine the role of plastid stromules (stroma filled tubules) in MEcPP-mediated plastid-to-nucleus retrograde signaling using proteomics and cell biological approaches. To undertake these specific objectives we have generated foundational data and unmatched experimental tools including suppressor lines reverted in their ability to induce stress response genes in spite of high MEcPP levels, microarray-based identification of histone deacetylase gene as potential epigenetic regulators of stress responses, and plastid expressing fluorescent protein lines that enable microscopy-based identification of chloroplast tubular extensions called "stromules" found in plants with enhanced MEcPP levels.