Defining the retrograde plastid-to-nucleus stress signaling pathway

描述（由申请人提供）：逆行信号是一种从细胞器到细胞核的通信途径，在生物体的许多过程中起着调节和协调的作用，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质体到核信号代谢物甲基赤藓糖醇环二磷酸（MEcPP），这是一种由甲基赤藓糖醇磷酸（MEP）途径产生的类异戊二烯前体。这是一种保守的信号通路，存在于植物、致病菌和植物的非光合质体“顶质体”中

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.