Monitoring mechanisms in mammalian ribosome biogenesis

哺乳动物核糖体生物发生的监测机制

基本信息

批准号：
8711482
负责人：
DIMITRI G PESTOV
金额：
$ 30.01万
依托单位：
ROWAN UNIVERSITY SCHOOL/OSTEOPATHIC MED
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-02-01 至 2016-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8711482
关键词：
Address Anabolism Animal Model Antineoplastic Agents Biogenesis Biological Cell Cycle Arrest Cell Nucleolus Cell physiology Cells Complex Defect Disease Drug Targeting 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

项目摘要

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.

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来制造蛋白质，尤其是在活跃生长和增殖时期。真核生物中的每个核糖体都是通过复杂的组装途径制造的，需要 200 多种辅助蛋白质因子。与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缺陷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不正确构建的核糖体？本研究的主要目的是通过阐明哺乳动物细胞核糖体合成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，因为哺乳动物的监测机制在许多方面与酵母等其他模式生物的监测机制不同。这些差异之一是哺乳动物核糖体形成的缺陷会诱导 p53 介导的核仁应激反应，但其机制尚不完全清楚。由于前核糖体的框架与核糖体本身一样，由 RNA 组成，因此核糖核酸酶在拆除有缺陷的核糖体前体方面发挥着关键作用。在这里，我们希望建立核糖核酸外切酶启动消除有缺陷的前核糖体过程的途径。我们的项目有三个具体目标。 1.确定哺乳动物外泌体在错误组装的前60S亚基降解中的作用。我们将确定外泌体是否在错误组装的 60S 前亚基的初级监测中发挥作用，或者充当清道夫，以及如何通过候选接头来调节这些活动。 2. 确定 60S 之前的亚基的结构特征，这些特征控制着它是否会被加工或降解。我们的模型是前核糖体的某些成分充当控制核酸酶进入前 rRNA 的看门人。这将通过剖析核酸外切酶 Xrn2 和 60S 前亚基中的 5.8S RNA-核糖体蛋白复合物之间的相互作用来测试。 3. 确定前 rRNA 衰变产物是否在核糖体组装因子突变和阻止核糖体成熟的抗癌药物诱导的核仁应激反应中发挥作用，这两种药物都会显着增加核酸酶对前 rRNA 的分解。这些研究将共同检验这样的假设：哺乳动物核糖核酸外切酶对前 rRNA 的监视具有双重功能，即在正常情况下实现核糖体的准确合成，并在系统过载时启动应激信号传导。