Alternative 18S rRNA 3' processing pathways in human ribosome biogenesis

生命依赖于有机体通过控制复杂大分子的合成来对不断变化的环境和压力做出反应的能力。正常的细胞生长需要核糖体的产生，核糖体是制造所有细胞蛋白质的基本RNA-蛋白质机制。核糖体组装是一个复杂的过程，涉及数百个生物发生因素，是细胞能量的主要消耗者，因此受到严格控制。在癌细胞中，核糖体的产生被上调以促进细胞增殖。许多细胞压力和20种遗传病(“核糖病”)导致核糖体生产受阻或缺陷。令人惊讶的是，核糖体病患者往往容易患癌症，最近一些癌症也被认为与核糖体生产缺陷有关。在人类中，核糖体组装控制着肿瘤抑制基因P53，它是“基因组的守护者”。通过细胞信号传递，P53确保细胞对应激条件做出适当的反应，如果个别细胞对整个生物体有害，甚至可以诱导细胞死亡。事实上，在许多核糖病中，P53水平升高，P53是这些疾病中观察到的许多临床特征所必需的。在这里，我们建议研究关键生物发生因子中与疾病相关的突变对人类核糖体生产、P53和细胞存活的影响。我们在核糖体生物发生、RNA加工和细胞信号方面的国际公认的专业知识，加上我们强大的初步数据，意味着我们处于成功实施这一项目的理想位置。由于核糖体生产机械的高度进化保守，长期以来一直认为人类的核糖体生产与酵母的核糖体生产相同，酵母是研究这一过程的主要模式生物。然而，我们现在已经证明，人类核糖体的生产过程要复杂得多，而且从根本上不同于酵母中使用的过程。令人惊讶的是，人类细胞也保留了“酵母样”机制所需的机械，然而，这一途径在人类中很少使用，目前还不清楚它扮演着什么角色。因此，增加我们对人类核糖体生产的基础知识对于阐明几种人类疾病的基础和开发潜在的治疗方法是至关重要的。因此，我们将解决两个关键问题：1)关键核糖体RNA成熟因子中与疾病相关的突变是否会导致核糖体生产的缺陷或变化？2)为什么人类细胞在拥有使用“酵母状”机制的机制的情况下，还要使用专门的核糖体RNA成熟途径？我们将使用强大的分子工具和最先进的技术相结合来揭示人类核糖体生产的机制(S)，并了解这种机制在疾病中是如何改变的。该项目将包括确定疾病相关突变对人类核糖体生产和p53依赖的细胞信号的影响，以及使用新的方法来理解为什么人类细胞使用专门的核糖体生产途径。有趣的是，我们的初步数据还表明，一些癌细胞可能依赖于次要的“酵母样”机制。这增加了一种令人兴奋的可能性，即这一途径可能成为未来抗癌药物开发的靶点。

Life depends on the ability of an organism to react to changing environments and stresses by controlling the synthesis of complex macromolecules. Normal cell growth requires the production of ribosomes, the essential RNA-protein machinery that makes all cellular proteins. Ribosome assembly, a complicated process involving hundreds of biogenesis factors, is the major consumer of cellular energy and therefore tightly controlled. In cancer cells, ribosome production is upregulated to promote cell proliferation. Many cellular stresses and 20 genetic diseases ("ribosomopathies") result in a block or defect in ribosome production. Surprisingly, ribosomopathy patients are often pre-disposed to cancer and some cancers have also recently been linked to defective ribosome production. In humans, ribosome assembly controls the tumour suppressor p53, the "guardian of the genome". Through cellular signaling, p53 ensures appropriate cellular responses to stress conditions, and can even induce cell death if individual cells are detrimental to the whole organism. Indeed, p53 levels are elevated in many ribosomopathies and p53 is essential for many of the clinical features observed in these diseases.Here, we propose to study the impact of disease-associated mutations in key biogenesis factors on human ribosome production, p53 and cellular survival. Our internationally recognised expertise in ribosome biogenesis, RNA processing and cellular signaling, together with our strong preliminary data, mean that we are ideally placed to successfully carry out this project.Due to the high degree of evolutionary conservation in the ribosome production machinery, it was long assumed that ribosome production is the same in humans as it is in yeast, the main model organism used to study this process. However, we have now shown that the process of human ribosome production is significantly more complicated, and fundamentally different to that used in yeast. Surprisingly, human cells also retain the machinery needed for a "yeast-like" mechanism, however, this pathway is rarely used in humans and it is unclear what role it plays. Increasing our fundamental knowledge of human ribosome production is therefore of paramount importance for elucidating the basis of several human diseases and the development of potential treatments.WE WILL THEREFORE ADDRESS TWO KEY QUESTIONS:1) Do disease-associated mutations in key ribosomal RNA maturation factors cause defects or changes in ribosome production?2) Why do human cells use a specialised ribosomal RNA maturation pathway when they also have the machinery to employ a "yeast-like" mechanism?We will use a powerful combination of molecular tools and state-of-the-art technologies to reveal the mechanism(s) of human ribosome production and understand how this is altered in disease. This project will include determining the impact of disease-associated mutations on human ribosome production and p53-dependent cellular signaling, as well as using novel approaches to understand why human cells use a specialised ribosome production pathway. Intriguingly, our preliminary data also suggest that some cancer cells might depend on the minor, "yeast-like" mechanism. This raises the exciting possibility that this pathway could be targeted for the development of anti-cancer drugs in the future.