Structural and Functional Studies of Eukaryotic Exosomes

描述(申请人提供)：RNA的寿命和丰度是通过改变RNA转录和RNA降解之间的平衡来调节的。真核生物中存在两条主要的RNA衰变途径，一条是催化5‘到3’方向的降解，另一条是沿3‘到5’方向降解RNA。3‘到5’衰变途径需要RNA外体的活性，它是一个大的多亚基蛋白质复合体，包含一个由9个亚基和2个附加亚基组成的非催化核心，催化3‘到5’RNA外切核酸酶的进行性和分布性活性。在萌芽酵母中，11个基因中有10个是生长所必需的，这表明了RNA外切体及其在细胞功能中的活动的重要性。虽然最近的工作阐明了真核细胞外体结构和功能的基本方面，但关于外体亚单位在RNA加工和衰退中的个体和集体活动仍然存在许多问题。RNA衰变途径在真核细胞的核酸代谢中起着不可或缺的作用，因此我们的研究直接关系到人类的健康和NIH的使命，因为RNA加工和衰退的错误调控与癌症、炎症和神经退行性疾病等疾病状态有关。这项建议将通过确定单个外切体亚基的特征，通过重组多个亚基RNA外切体，并通过分析这些复合体在生化、遗传和结构研究中的活性来解决人类和酵母RNA外切体生物学的中心问题，这些研究将确定RNA外切体在体外和体内RNA降解过程中的功能。 与公共健康相关：真核RNA外切体是一种重要的复合体，通过其3‘到5’的加工和衰变活动来调节RNA的动态平衡。RNA外切体还通过以异常RNA分子为目标进行破坏的质量控制途径，对RNA监测做出贡献。这些途径共同调节特定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，在信号转导中发挥至关重要的作用。RNA外切体还可以保护细胞免受可能导致细胞病理的有害RNA的影响。这些通路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.