Structural and Functional Studies of Eukaryotic Exosomes

描述（由申请人提供）：通过改变RNA转录和RNA降解之间的平衡来调节RNA寿命和丰度。真核生物中存在两种主要的RNA降解途径，一种催化5'至3'降解，而另一种在3'至5'方向降解RNA。3'至5'衰变途径需要RNA外泌体的活性，RNA外泌体是一种大型多亚基蛋白质复合物，其含有9个亚基的非催化核心和催化进行性和分配性3'至5' RNA核糖核酸外切酶活性的两个另外的亚基。在芽殖酵母中，11个基因中有10个是生长所必需的，这表明RNA外泌体及其在细胞功能中的重要性。虽然最近的努力阐明了真核外泌体结构和功能的基本方面，但在RNA加工和衰变中外泌体亚基的个体和集体活动方面仍然存在许多问题。RNA衰变途径在真核核酸代谢中起着不可或缺的作用，因此我们的研究与人类健康和NIH的使命直接相关，因为RNA加工和衰变的失调与疾病状态如癌症，炎症和神经退行性疾病有关。该提案将解决人类和酵母RNA外泌体生物学的核心问题，通过表征单个外泌体亚基，通过重组多亚基RNA外泌体，并通过分析这些复合物在生物化学，遗传学和结构研究中的活性，这些研究将在体外和体内RNA降解过程中建立RNA外泌体的功能。 公共卫生相关性：真核生物RNA外泌体是一种重要的复合物，通过3'至5'加工和降解活动调节RNA的稳态。RNA外泌体也有助于通过靶向异常RNA分子进行破坏的质量控制途径进行RNA监测。这些通路共同调节特定RNA的寿命，从而通过控制与信号级联相关的RNA表达的瞬时爆发的持续时间在信号转导中起重要作用。RNA外泌体还保护细胞免受可能导致细胞病理学的有害RNA的影响。这些途径的缺陷与几种人类疾病有关，包括癌症、炎症和神经退行性疾病。

DESCRIPTION (provided by applicant): RNA lifetime and abundance is regulated by shifting the balance between RNA transcription and RNA degradation. Two principle RNA decay pathways exist in eukaryotes, one catalyzes degradation 5' to 3' while the other degrades RNA in the 3' to 5' direction. The 3' to 5' decay pathway requires the activities of the RNA exosome, a large multi-subunit protein complex that contains a non-catalytic core of nine subunits and two additional subunits that catalyze processive and distributive 3' to 5' RNA exoribonuclease activities. In budding yeast, ten of the eleven genes are essential for growth, suggesting the importance of the RNA exosome and its activities in cellular function. While recent efforts illuminated fundamental aspects of eukaryotic exosome structure and function, many questions remain with respect to the individual and collective activities for exosome subunits in RNA processing and decay. RNA decay pathways play an integral role in eukaryotic nucleic acid metabolism, so our studies are of direct relevance to human health and the mission of the NIH because misregulation of RNA processing and decay is associated with disease states such as cancer, inflammation and neurodegenerative diseases. This proposal will address the central issues of human and yeast RNA exosome biology by characterizing individual exosome subunits, by reconstituting multi-subunit RNA exosomes and by analyzing the activities of these complexes in biochemical, genetic and structural studies that will establish functions for the RNA exosome during RNA degradation in vitro and in vivo. PUBLIC HEALTH RELEVANCE: The eukaryotic RNA exosome is an essential complex that regulates RNA homeostasis through its 3' to 5' processing and decay activities. RNA exosomes also contribute to RNA surveillance via quality control pathways that target aberrant RNA molecules for destruction. Together, these pathways regulate the lifetime of particular RNAs and thus serve a vital role in signal transduction by controlling the duration of transient bursts of RNA expression that are associated with signaling cascades. The RNA exosome also protects the cell from deleterious RNA that could lead to cellular pathology. Defects in these pathways are associated with several human diseases including cancer, inflammation, and neurodegenerative disorders.