The Control of Gene Expression by Eukaryotic Ribonucleases

项目摘要/摘要 RNA降解在基因表达调控中起着多种重要作用。它 不仅调节全球转录丰度，还提供质量控制 消除未正确处理或错误本地化的记录的机制，或 含有提前翻译终止密码子(PTCs)。在我们的实验室工作 聚焦于真核细胞中两个主要的RNA降解途径：胡说八道- 介导的衰变(NMD)，它降解含有PTC的转录本，以及Exosome， 它处理各种非编码RNA，并在 质量控制流程。基因组学方法和经典遗传学的结合 生化分析使我们能够确定这些途径在 基因调控，包括剪接位点选择的校对、特异性的调控 MRNAs和Pol.II不同终止模式的潜在机制。我们有 还确定了临床上外切体亚单位突变的分子后果 与桥小脑发育不全(PCH)有关。本申请中提出的工作 将广泛地扩展我们对外体亚单位作用的理解 其在全基因组范围内对RNA加工和降解的相关因素。此外，我们 将决定应激期间外切体的活动是如何被控制的，以及它是如何 与其他RNA质量控制途径合作，例如耦合到 翻译。最后，我们将描述促进3‘端形成的机制 对于一类新的mRNAs，它使用一种完全独立于 经典的切割和多聚腺苷酸化途径。整体而言，拟议的研究将会 为我们理解真核生物所涉及的机制提供重大进展 转录后调控和RNA加工。

Project Summary/Abstract RNA degradation plays multiple essential functions in the control of gene expression. It not only regulates global transcript abundance, but also provides quality control mechanisms to eliminate improperly processed or mis-localized transcripts, or those containing premature translation termination codons (PTCs). Work in our laboratory focuses on two major RNA degradation pathways in eukaryotic cells: Nonsense- Mediated Decay (NMD), which degrades PTC-containing transcripts, and the Exosome, which processes a variety of non-coding RNAs and also degrades transcripts during quality-control processes. A combination of genomic approaches and classical genetic and biochemical analyses has allowed us to identify new roles for these pathways in gene regulation, including proofreading of splice site selection, regulation of specific mRNAs and the mechanisms underlying distinct modes of Pol.II termination. We have also identified the molecular consequences of clinical mutations in exosome subunits implicated in pontocerebellar hypoplasia (PCH). The work proposed in this application will broadly expand our understanding of the role of the subunits of the exosome and of its associated factors on RNA processing and degradation genome-wide. In addition, we will determine how the activity of the exosome is controlled during stress, and how it cooperates with other RNA quality control pathways such as those coupled to translation. Finally we will characterize the mechanisms that promote 3´-end formation for a novel class of mRNAs, which use a mechanism completely independent from the classical cleavage and polyadenylation pathway. Overall, the proposed studies will provide major advances in our understanding of the mechanisms involved in eukaryotic post-transcriptional regulations and RNA processing.