Monitoring mechanisms in mammalian ribosome biogenesis

哺乳动物核糖体生物发生的监测机制

• 批准号: 8187767
• 负责人: DIMITRI G PESTOV
• 金额: $ 29.45万
• 依托单位: UNIV OF MED/DENT NJ-SCH OSTEOPATHIC MED
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8187767
• 关键词: Address; Anabolism; Animal Model; Antineoplastic Agents; Biogenesis; Biological; Cell Cycle Arrest; Cell Nucleolus; Cell physiology; Cells; Complex; Defect; Disease; Drug Delivery Systems; Ensure; Enzymes; Eukaryota; Exonuclease; Exoribonucleases; Gatekeeping; Genetic; Grant; Growth; Induced Mutation; Link; Malignant Neoplasms; Mammalian Cell; Mammals; Mediating; Messenger RNA; Metabolic; Modeling; Molecular; Molecular Conformation; Molecular Machines; Monitor; Mus; Mutation; Organism; Outcome; Pathogenesis; Pathway interactions; Phosphodiesterase I; Play; Process; Proteins; Proteome; Quality Control; RNA; RNA Decay; Regulation; Research; Ribonucleases; Ribosomal Proteins; Ribosomal RNA; Ribosomes; Role; Signal Transduction; Site; Small Nucleolar RNA; Stress; System; Testing; Toxic effect; Yeasts; base; biological adaptation to stress; disease-causing mutation; mutant; nanomachine; novel diagnostics; nuclease; overexpression; poly A specific exoribonuclease; protein complex; rRNA Precursor; theories; tool

DESCRIPTION (provided by applicant): Ribosomes are biological nanomachines that carry out synthesis of the entire cellular proteome. Cells require a large number of ribosomes to make proteins, especially during periods of active growth and proliferation. Each ribosome in eukaryotes is manufactured through an elaborate assembly pathway that requires more than 200 accessory protein factors. Like any other complex assembly process, biosynthesis of ribosomes generates a certain fraction of defective products and kinetically trapped intermediates. How do cells distinguish between ribosomes that are built correctly and those that are not? The main objective of the proposed research is to answer this question by elucidating the mechanisms underlying quality control of ribosome synthesis in mammalian cells. We use mouse cells in our studies because surveillance mechanisms in mammals differ in many aspects from those in other model organisms such as yeast. One of such differences is that defects in ribosome formation in mammals induce a p53-mediated nucleolar stress response, which is mechanistically not completely understood. Because the framework of preribosomes, like the ribosome itself, is made of RNA, ribonucleases play a key role in dismantling defective ribosome precursors. Here, we wish to establish the pathway through which exoribonucleases start the process of elimination of the defective preribosomes. Our project has three specific aims. 1. Determine the role of the mammalian exosome in the degradation of misassembled pre-60S subunits. We will determine whether the exosome functions in primary surveillance of misassembled pre-60S subunits or acts as a scavenger and how these activities may be regulated through candidate adaptors. 2. Identify structural features of the pre-60S subunit that control whether it will be processed or degraded. Our model is that certain components of preribosomes act as gatekeepers that control nuclease access to pre-rRNA. This will be tested by dissecting the interactions between the exonuclease Xrn2 and the 5.8S RNA-ribosomal protein complex in pre-60S subunits. 3. Determine if pre-rRNA decay products play a role in the nucleolar stress response induced by mutations in ribosome assembly factors and by anticancer drugs that block ribosome maturation, both of which significantly increase pre-rRNA breakdown by nucleases. Together, these studies will test the hypothesis that pre-rRNA surveillance by mammalian exoribonucleases serves the dual function of enabling accurate synthesis of ribosomes under normal circumstances, and initiating stress signaling when the system becomes overloaded. PUBLIC HEALTH RELEVANCE: This project will answer important questions about how mammalian cells ensure the accurate synthesis of ribosomes, the molecular machines that make all proteins in an organism. Defects in ribosome formation are known to be a factor in cancer and several congenital diseases, and our study will help to understand the molecular basis of this connection.

描述（由申请人提供）：核糖体是进行整个细胞蛋白质组合成的生物纳米机器。细胞需要大量核糖体才能生产蛋白质，尤其是在活跃生长和增殖期间。真核生物中的每个核糖体都是通过精美的装配途径制造的，该途径需要200多个辅助蛋白因子。像任何其他复杂的组装过程一样，核糖体的生物合成会产生一定比例的有缺陷的产物和动力学捕获的中间体。细胞如何区分正确构建的核糖体和未建立的核糖体？拟议研究的主要目的是通过阐明哺乳动物细胞中核糖体合成的质量控制的机制来回答这个问题。我们在研究中使用小鼠细胞是因为哺乳动物的监视机制在许多方面与其他模型生物（如酵母）的不同方面有所不同。这种差异之一是，哺乳动物中核糖体形成的缺陷诱导p53介导的核仁应力反应，从机械上讲，这是没有完全理解的。由于像核糖体本身一样，核糖体的框架是由RNA制成的，因此核糖核酸酶在拆卸有缺陷的核糖体前体中起着关键作用。在这里，我们希望建立远高核酸酶开始消除有缺陷的前体的途径。我们的项目具有三个特定的目标。 1。确定哺乳动物外泌体在60年代前亚基降解中的作用。我们将确定在缩减60年代之前的主要监测中，外泌体功能是在缩减的单位中还是作为清道夫的起作用，以及如何通过候选适配器调节这些活动。 2。确定控制它是否将被处理或退化的60年前亚基的结构特征。我们的模型是，某些成分的成分充当控制核酸酶访问前RRNA的守门人。这将通过在60年代前亚基中解剖核酸外切酶XRN2和5.8S RNA-ribosomal蛋白复合物之间的相互作用来测试。 3。确定前RRNA衰减产物是否在核糖体组装因子中突变引起的核仁应力反应以及阻断核糖体成熟的抗癌药物中起作用，这两种药物都大大增加了核酸酶的前RRNA崩溃。总之，这些研究将检验以下假设：哺乳动物驱虫核酸酶的前rNNA监测具有双重功能，即在正常情况下能够准确合成核糖体，并在系统过载时启动应力信号。 公共卫生相关性：该项目将回答有关哺乳动物细胞如何确保核糖体的准确合成的重要问题，核糖体是生物体中所有蛋白质的分子机器的准确合成。核糖体形成的缺陷已知是癌症和几种先天性疾病的一个因素，我们的研究将有助于理解这种联系的分子基础。