Monitoring mechanisms in mammalian ribosome biogenesis

描述（由申请人提供）： 新的核糖体的合成是一种基本的细胞活动，并且越来越清楚的是，核糖体生物合成在癌症和人类疾病中起着重要作用。然而，这一高度复杂过程的分子机制及其与其他细胞途径的联系仍然没有得到充分的理解，特别是在哺乳动物系统中。最近的证据表明，哺乳动物细胞拥有一个监视系统，该系统将核糖体合成中的扰动传递给肿瘤抑制因子p53。目前尚不清楚核糖体组装中的错误如何被识别，以及核糖体生物发生机制中的哪些组分介导p53途径的信号传导。我们试图通过分析新发现的核仁GTP结合蛋白（GTP酶）Nog 1和Nug 1A/B来了解哺乳动物细胞中核糖体生物合成的监测机制。最近的实验证据表明，这些GTP酶的功能是必不可少的60 S核糖体亚基的合成，也暗示它们作为核糖体合成和增殖控制途径之间的潜在信号联系。本研究旨在阐明哺乳动物核仁GTPases在核糖体生物合成的监视中的作用，并深入了解其作用的分子机制。我们将开始解决两个问题，以评估监测功能的核仁GTP酶。小鼠Nog 1和Nug 1A/B在rRNA成熟中的作用是什么？它们的功能如何有助于核糖体生物合成的准确性和p53网络的信号传导？通过使用生物化学和遗传学方法的组合，我们将进一步研究代表该组的模型Nog 1的分子机制。鸟嘌呤核苷酸的结合和水解在这种GTdR的活性中起什么作用？哪些蛋白质作为Nog 1功能的效应子和调节子，它们如何影响其GT3循环？总的来说，这些研究应该提供一组新的GTP结合蛋白的重要的新信息，产生核糖体组装的机制的见解，并有助于我们了解哺乳动物细胞中的核糖体生物合成和增殖控制之间的联系。

DESCRIPTION (provided by applicant): Synthesis of new ribosomes is an essential cellular activity and it is becoming increasingly clear that ribosome biogenesis plays an important role in cancer and human disease. However, molecular mechanisms of this highly complex process and its links to other cellular pathways remain inadequately understood, especially in a mammalian system. Recent evidence indicates that mammalian cells possess a surveillance system that communicates perturbations in ribosome synthesis to the tumor suppressor p53. It is currently unknown how errors in ribosome assembly are recognized and which components in the ribosome biogenesis machinery mediate signaling to the p53 pathway. We seek to understand the mechanisms that provide monitoring of ribosome biogenesis in mammalian cells through analysis of the newly discovered nucleolar GTP-binding proteins (GTPases) Nog1 and Nug1A/B. Recent experimental evidence shows that the function of these GTPases is essential for synthesis of 60S ribosomal subunits and also implicates them as potential signaling links between ribosome synthesis and proliferation control pathways. The studies proposed here are designed to elucidate the role of the mammalian nucleolar GTPases in surveillance of ribosome biogenesis and to gain insight into the molecular mechanisms of their action. We will begin by addressing two questions to assess the monitoring function of the nucleolar GTPases. What is the role of mouse Nog1 and Nug1A/B in rRNA maturation? How does their function contribute to the accuracy of ribosome biogenesis and signaling to the p53 network? By using a combination of biochemical and genetic approaches, we will further investigate the molecular mechanisms of a model representative of the group, Nog1. What role do guanine nucleotide binding and hydrolysis play in the activities of this GTPase? What proteins serve as effectors and regulators of Nog1 function and how do they influence its GTPase cycle? Collectively, these studies should provide significant new information on a novel group of GTP-binding proteins, yield mechanistic insights into ribosome assembly and contribute to our understanding of the link between ribosome biogenesis and proliferation control in mammalian cells.