Mechanisms of substrate selectivity of the nuclear RNA exosome complex.

细胞的生长、发育和对流体环境的成功适应需要成千上万个基因的精心表达。RNA稳定性的协调变化在不同细胞状态之间的转换中起着重要作用，是许多应激反应途径的组成部分。3 ‘至5 ’外核溶解RNA外泌体复合物是细胞中RNA稳定性的主要调节因子，并降解多种类型的RNA底物。它参与了许多rna加工事件，同时专门针对虚假和异常rna进行破坏，并在转录后基因调控中起作用。外泌体忠实地识别其底物的能力是其在细胞中调节功能的基础，对细胞健康至关重要。核RNA外泌体的失调导致癌症和疾病。我研究的总体目标是确定参与外泌体选择性调节的机制。虽然复合物的分子功能和结构已经被很好地理解，但决定底物选择性和允许调节其活性的因素在很大程度上仍然是模糊的。该项目将解决该领域的关键突出问题：核RNA监测机制如何区分虚假转录本和功能性转录本？外泌体靶向涉及哪些因素？底物选择是如何响应外部信号而调节的？特别是，使用基于RNA相互作用体捕获技术的比较蛋白质组学方法，我想鉴定将RNA底物导向外泌体的RNA结合蛋白，并旨在了解这些因素如何决定外泌体复合物的特异性。这些蛋白质如何识别它们的底物，它们又是如何促进RNA衰变的？我研究的一个特别重点将是细胞应激条件对外泌体复合物底物特异性的影响，以确定有助于驱动细胞适应的动态外泌体靶向机制，特别是在响应DNA损伤时。DNA损伤触发了一个复杂的基因调控程序，可以作为转录和转录后机制在细胞抗逆性中的作用的范例。必不可少的RNA解旋酶Dbp2在这个过程中起着至关重要的作用，我想详细了解它的功能。总之，这些研究将是我们理解转录后机制如何塑造促进生存和决定细胞命运的基因表达程序的基础。

Cell growth, development and successful adaptation to a fluid environment require the orchestrated expression of thousands of genes. Coordinated changes in RNA stability play an important role during transitions between different cellular states, and are an integral component of many stress response pathways. The 3’ to 5’ exonucleolytic RNA exosome complex is a major regulator of RNA stability in the cell and degrades many types of RNA substrates. It is involved in numerous RNA-processing events while specifically targeting spurious and aberrant RNAs for destruction, and also acts in post-transcriptional gene regulation. The ability of the exosome to faithfully identify its substrates is the basis of its regulatory functions in the cell and is of utter importance for cellular well-being. Dysregulation of the nuclear RNA exosome leads to cancer and disease.The overall goal of my research is to define the mechanisms involved in the regulation of exosome selectivity. While the molecular function and the structure of the complex are very well understood, the factors that determine substrate selectivity and allow regulation of its activity remain largely obscure. This project will address key outstanding questions in the field: How can the nuclear RNA surveillance machinery distinguish spurious transcripts from functional ones? What factors are involved in exosome targeting and how is substrate selection regulated in response to external cues? In particular, using a comparative proteomics approach based on the RNA interactome capture technique, I want to identify RNA-binding proteins that direct RNA substrates towards the exosome, and aim to understand how these factors determine the specificity of the exosome complex. How do these proteins recognise their substrates, and how do they promote RNA decay? A particular focus of my research will be the effect of cellular stress conditions on the substrate specificity of the exosome complex to identify dynamic exosome targeting mechanisms that help to drive cellular adaptation, specifically in response to DNA damage. DNA damage triggers a complex gene regulatory programme that can be taken as a paradigm for the role of transcriptional and post-transcriptional mechanisms in cellular stress resistance. The essential RNA helicase Dbp2 plays a vital role in this process, and I want to understand its function in detail. Together, these studies will be fundamental for our understanding of how post-transcriptional mechanisms shape gene expression programs that promote survival and determine cell fate.