Impact of Argonaute 2 (AGO2) PAZ domain mutations on miRNA turnover, target interaction and tumour development

MicroRNAs （miRNAs）是一类保守的小rna，在许多细胞和发育过程的调控中起重要作用。它们引导AGO复合物靶向mrna，并降低其稳定性和翻译能力。据估计，mirna调节约60%的mrna的表达。mirna的错误调控与细胞稳态的破坏和肿瘤的发展有关。mirna可以促进肿瘤发生或抑制肿瘤发生，这取决于它们的靶标特异性和环境。迄今为止，关于miRNA转换调控的知识有限。先前的研究表明，破坏miRNA 3 '端和AGO PAZ结构域之间的关键相互作用足以诱导广泛的修饰。这些突变将miRNA 3 '端从PAZ结构域内的保护口袋中释放出来，使其易于被剪切和修剪，从而导致降解。我们项目的目的是进一步评估AGO PAZ结构域突变在癌症中的作用。基于之前的研究，我们假设在癌症患者中发现的AGO PAZ结构域突变可能通过调节miRNA池中单个miRNA的丰度或通过改变靶mrna的结合和抑制来促进肿瘤进展。该项目将分为两个主要目标：目标1旨在了解AGO2 PAZ突变对miRNA谱和miRNA修饰和衰变的一般影响以及下游效应。目的2旨在了解AGO2 PAZ突变在癌症中的作用。为此，我们将建立一个在癌症患者中确认或可能发生的AGO2 PAZ突变体文库，并分析它们对miRNA库和细胞行为的影响。在整个项目中，我们将把大数据集分析与细胞生物学、RNA和蛋白质生物化学技术结合起来。展望未来，我们的数据可用于鉴定新的生物标志物或靶向治疗方法。

MicroRNAs (miRNAs) are a conserved class of small RNAs with important roles in the regulation of many cellular and developmental processes. They guide AGO complexes to target mRNAs, and decrease their stability and translation. It has been estimated that miRNAs regulate the expression of ~60% of mRNAs. Misregulation of miRNAs has been linked to disruption of cell homeostasis and tumour development. miRNAs can either promote tumorigenesis or suppress it depending on their target specificity and the context. To date, there is limited knowledge on the regulation of miRNA turnover. Previous work has shown that disrupting critical interactions between the miRNA 3’ end and AGO PAZ domain was sufficient to induce extensive modifications. Those mutations released the miRNA 3’ end from its protective pocket within the PAZ domain making it accessible to tailing and trimming, thus leading to degradation. The aim of our project is to further evaluate the role of AGO PAZ domain mutations in cancer. Based on the previous studies, we hypothesize that mutations of the AGO PAZ domain found in cancer patients may contribute to tumor progression by regulating the abundance of individual miRNAs within the miRNA pool or by altering the binding and repression of target mRNAs. The project will be separated into two main objectives: Objective 1 aims to understand the general impacts of AGO2 PAZ mutations on the miRNA profile and miRNA modification and decay as well as downstream effects. Objective 2 aims to understand the role of AGO2 PAZ mutations in cancer. For this we will create a library of AGO2 PAZ mutants confirmed or likely to occur in cancer patients and analyze their impact on the miRNA pool and cellular behavior. Throughout the project we will combine the analysis of big data sets with techniques of cell biology and RNA and protein biochemistry. Prospectively, our data could be used for identification of new biomarkers or targeted therapy approaches.